CompassWinter 2011-12

Editor/Layout Assistant EditorsKimberly Robinson Cecilia Hennessy Kaitlin PallaFaculty Advisor Kejia PangDr. Rick Meilan Conor Keitzer

Compass Magazine Committee

At last, the long awaited Winter 2011-12 edition of Compass is here! This issue provides a window into some of the many exceptional and ground-breaking research projects being conducted in the Department of Forestry and Natural Resources. With great enthusiasm, graduate students involved in these projects share their stories with you.

Have you ever wondered how climate change may affect plants? What do Purdue students think about reusable water bottles? How does timber harvest affect woodland salamanders? What herbicides work best to control Boxelder? The answer to these and many more questions can be found in the following pages. So, grab a cup of coffee or cocoa, cozy up in a warm place, and begin exploring this edition of Compass!

Kimberly Robinson, Compass Editor

www.fnr.purdue.edu

Features

Articles

5What’s Wrong with the Tap?by Amber Saylor and Linda Prokopy

Climate Change, Nitrogen, and Plants, Oh My!by Novem Auyeung

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Cover Photos Provided By Steven Kimble.

10Emergence of Green Ash as a Research Toolby Shaneka Lawson

15Foliar Herbicide Control of Boxelder (Acer negundo)by Matt Kraushar, Zachary Lowe, and Harmon Weeks, Jr.

19The Effects of Timber Harvest on Woodland Salamandersby Jami MacNeil

13Catching the Drift: Environmental Awareness and Attitudes of Commercial Pesticide Applicatorsby Adam Reimer

22Transforming Populus in Order to Increase Water-Use Efficiencyby Matthew Caldwell

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Climate Change, Nitrogen, and Plants, oh My!by Novem Auyeung

Nitrogen is an essential nutrient for terrestrial plant growth, and plants rely on microbial communities to transform nitrogen gas (N2) in the atmosphere and soil organic matter – material from living or decaying organisms – into forms of nitrogen that are usable by plants. Plants mostly take up inorganic nitrogen -- forms of nitrogen that do not contain carbon atoms – such as ammonia/ammonium (NH3/NH4

+) and nitrate (NO3

-). In many habitats, plant-available forms of nitrogen are limiting; in other words, they have a strong influence on biological processes, such as plant growth, and increasing plant-available nitrogen can increase plant productivity. Because microbial com-munities are sensitive to environmental conditions, such as temperature and moisture, environmental changes likeclimate change couldhave a great impact on the processes that micro-organisms mediate, (e.g., the transformation of nitrogen into its manydifferent forms). This, in turn, can affect levels of plant-available nitrogen and plant pro-ductivity in agro-nomic and natural ecosystems. My research is focused on: 1) elucidating the effects of climate change on nitrogen cycling rates, 2) identifying some of the underlying mechanisms responsible for changes in nitrogen cy-cling rates, and 3) understanding how changes in ni-trogen cycling rates may affect plant-available nitro-gen. My research is based at the Boston Area Climate Experiment (BACE), a climate-change experimental field site in Waltham, Massachusetts. At the site, plots are heated with infrared heaters, providing four treatments: ambient (32 °F), low (~ 34 °F), medium

(~ 36 °F), and high (~ 39 °F). Precipitation is manip-ulated using a sprinkler system and rainout shelters to provide three treatments: ambient (average annual precipitation is 41.7 in/yr. in the Boston area) and 50% above and below ambient levels. Past studies have found that warming increases rates of nitrogen cycling. However, many experi-ments have shown that biological responses (e.g., decomposition, photosynthesis, soil respiration) to warming depend on soil water availability. As a result, it is useful to have experiments like the BACE so we can examine the interactive effects of warming and precipitation on biological processes, including nitrogen cycling. I n a ddition, past e cological studies have focused on biologi- cal processes dur- ing the growing season, because that is when most biologi- cal activity is thought to occur. More recent studies have found that changes in bio- logical processes in the winter can have a large influence on what happens in an ecosystem overall. For example, studies have found that much of the carbon that is stored in soils dur- ing the growing season is lost through soil respiration in the winter, and these findings have a significant impact on our understanding of soils and how they respond during different times of the year. For this reason, it is important to collect data throughout the year, even if it means doing field work while there is a foot of snow on the ground. Every two to three months from October 2008 to October 2010, I measured rates of net nitrogen miner-alization (the transformation of organic nitrogen into

The Boston Area Climate Experiment in Waltham, Massachusetts in Summer 2009.

Photo By Jeffrey Dukes

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There are a few reasons why this may be the case. First, most nitrogen mineralizing and nitrifying mi-crobes are aerobic – they require oxygen – and func-tion best in well-aerated soils. Because our field site has a relatively high mean annual precipitation, when there is an increase in precipitation, soils may become saturated with water and become oxygen-limited. This can slow down rates of microbial activity. Sec-ond, nitrate is the more abundant of the two forms of inorganic nitrogen, but it is highly mobile. Large rain events can cause the nitrate to leach or move out of the soil and become unavailable to plants. This suggests that an increase in net nitrogen mineraliza-tion and nitrification rates due to warming will not automatically lead to greater-plant available nitrogen or greater plant productivity, because much of this depends on the amount and timing of precipitation events. Overall, both warming and altered precipitation affect rates of net nitrogen mineralization and nitri-fication, potential nitrification rates, and inorganic nitrogen content in soils. As our climate changes, it is important to understand both the direction and mag-nitude of shifts in nitrogen cycling rates and nitrogen availability, because they strongly influence plant pro-ductivity in many agronomic and natural ecosystems. Plants provide us with countless ecosystem services: they provide food, wood products, soil-erosion con-trol, water purification, climate regulation (by storing carbon, and so on). Thus, it is in our best interest to understand how changes in our environment will af-fect their productivity.

inorganic nitrogen) and net nitrification (the con-version of ammonia/ammonium into nitrate) using field incubations of soil cores. I used DNA isolation techniques to collect data on the abundance and com-munity structure of ammonia-oxidizing bacteria and archaea (microbes that play an important role in nitri-fication). I also measured potential nitrification rates under a range of controlled conditions (e.g., different nutrient levels) in the lab so that I could compare lev-els of microbial activity in the lab to those in the field. To estimate levels of plant-available nitrogen in the field, I also measured soil inorganic nitrogen content in the field. My results indicate that soil warming increases rates of net nitrogen mineralization and net nitrifica-tion in the field, which is consistent with previous studies, and this effect varies depending on the time of year. Precipitation also changes net nitrogen mineral-ization rates and net nitrification rates in the field, and increasing precipitation can increase or decrease rates depending on the time of year. This means that the responses of nitrogen cycling to climate change may not be a straightforward increase due to warming. The effects of precipitation and the timing of precipitation can determine the direction and magnitude of changes in net nitrogen mineralization and nitrification. As such, it is important to take precipitation into account when making predictions about the response of nitro-gen conversion rates to climate change. With regard to microbial communities, the abun-dance of ammonia-oxidizing bacteria and archaea appears to have no correlation with net nitrogen mineralization or net nitrification rates, while potential nitrification rates are slightly correlated with net nitro-gen mineralization and net nitrification rates measured in the field. This suggests that microbial activity is responding to climate change even though the ammo-nia-oxidizer abundance is not. Hopefully, forthcom-ing data on the community structure of the ammonia-oxidizing microbes will shed light on whether this change in activity is due to changes in the community structure. How does all this affect plant-available nitrogen and plant productivity? Preliminary data reveal that warming increased inorganic nitrogen content, while increased precipitation decreased inorganic nitrogen content. This means that warming has the potential to increase plant-available nitrogen, but this increase is dampened by increases in precipitation.

Novem Auyeung collecting soil cores in January 2009.

Photo By Carol Goranson & Hollie Emery

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What’s Wrong With The Tap?by Amber Saylor and Linda Prokopy

Over the past decade in the U.S., trust in tap water has declined while consumption of bottled water has more than doubled to a yearly average of 30 gallons per person. Purdue University is no exception to this trend, and according to the Coordinator of Retail Sales and Marketing for the University Residences, bottled water is the best-selling item in campus mini-marts. The choice to drink bottled water has significant environmental impacts that can be avoided by drink-ing tap water. Bottled water requires large amounts of energy to produce and distribute. In 2009, Gleick and Cooley1 calculated that the 33 billion liters of bottled water consumed in the United States in 2007, “…required an energy input equivalent of between 32 and 54 million barrels of oil…” A landfill is the typi-cal “endpoint” in the life cycle of a single-use water bottle, where it can take centuries to decompose. In the U.S., only about 15% of plastic water bottles are recycled, which can require significant additional energy as well. Because nearly all the energy and materials used to produce these bottles are derived from oil, the environmental impact of this product is huge compared to tap water. Convincing the public to adopt sustainable behav-iors, such as drinking tap water instead of bottled

water, is an increasingly urgent task. Social market-ing has been used to promote a variety of sustainable behaviors in diverse contexts. Before designing a campaign, it is critical to identify the population’s beliefs and current behaviors, as well as what they perceive to be the important barriers and benefits of engaging in the desired behavior. Rather than rely-ing solely on educating the public, social marketing strives to decrease the barriers and increase the ben-efits of the desired behavior to make it easier for peo-ple to change. Given the widespread use of bottled water on campus, a social marketing campaign for tap water could be a useful strategy to reduce bottled wa-ter consumption and increase sustainability at Purdue. While some studies have addressed public per-ceptions of drinking water, there are still gaps in our understanding of how perceptions of risk and environmental impacts interact and influence behav-ior. The purpose of this research was to assess and understand current behaviors and beliefs about drink-ing water at Purdue University. Through the use of a survey and multiple interviews, we sought to uncover what factors individuals consider when choosing be-tween tap water and bottled water. Given the limited knowledge of perceptions of drinking water, this was an exploratory study that addressed the following research questions:

1) What are the current behaviors of Purdue University students, faculty, and staff with re- gard to consuming bottled water and/or tap water and using reusable water bottles? 2) What do Purdue University students, faculty, and staff perceive to be important barriers and benefits to drinking bottled water versus tap water from a reusable water bottle? 3) What does the Purdue community believe about the environmental impacts of drinking bottled water?

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Using refillable water bottles is a great alternative to drinking water packaged in

single-use plastic bottles.

1. Gleick, P.H., and H.S. Cooley. 2009. Energy im-plications of bottled water. Environmental Research Letters 4: pgs. 1-6.

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4) What role do Purdue students, faculty, and staff perceptions of health risks from tap water, bottled water, and reusable water bottles play in their decision to drink bottled water or tap water?

The survey was administered online to a random sample of undergraduate and graduate students, faculty, and staff drawn from the university tele-phone directory. A total of 677 questionnaires were fully completed, for a response rate of 33%. For the interviews, Purdue undergraduates were sampled by gender and race in order to capture a variety of perspectives. A total of 25 undergraduate students were approached in common areas on campus and 21 agreed to be interviewed (12 males, 9 females), for a response rate of 84%. Survey respondents drink an average of 4.8 single-serving bottles of water per week. Figure 1 shows that most respondents drink at least one bottle of water per week, while 44% drink three or more per week. A majority of survey respondents have tried re-usable water bottles, but only 40% use one regularly. These results indicate that, overall, Purdue residents more often drink bottled water than tap water out of reusable water bottles. Significant differences were also found between campus groups. Undergraduate survey respondents (totaling a sample size of 200 individuals) consume an average of 6.9 bottles of water per week—two more than the mean for all respondents. Among the undergraduates interviewed, the average amount of bottled water consumed is 7.7 bottles per week. In contrast, a majority of faculty and graduate students do not drink bottled water (55% and 54%,

respectively). Survey respondents tend to agree that consump-tion of bottled water causes environmental damage, but downplay their own contribution to the collective environmental impact, as suggested by the statistics below:

• 47% of respondents believe that global consump- tion of bottled water causes some significant environmental damage, and 28% believe it causes a lot of damage. • 23% believe their individual behavior causes only insignificant damage and 15% believe it causes a lot of damage. • 36% said if they recycled the bottles, drinking bottled water would cause only insignificant damage, while 13% believed it would have no environmental impact. • 31% believe that even if they recycled the bottles there would be some environmental damage.

The interviewed undergraduates express a limited understanding of the environmental impacts of bottled water. Most students either do not consider envi-ronmental impacts when choosing drinking water, or believe that recycling the bottles would reduce or eliminate any environmental consequences. Some in-terviewees came up with a few specific consequences, the most common being that “plastic persists in the environment” (10 respondents) and that “bottled wa-ter is a waste of plastic” (10 respondents). A related belief was, “feelings of guilt about environmental impacts of bottled water.” If students believe, albeit incorrectly, that recycling the bottles eliminates the environmental impacts of their ‘bad habit,’ they can

Above, “n” represents the number of individuals who responded to each survey question

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7soothe their guilty conscience without changing their underlying behavior. Respondents to the survey who consumed eight or more bottles of water per week, categorized as “Heavy Users” for analysis purposes, more strongly agreed that the following were barriers to drinking tap water than those who consumed no bottled water.

• I could get sick from germs growing in a reusable water bottle if I don’t keep it clean. • I don’t like the taste of tap water as much as bottled water. • Bottled water is offered for free at events and meetings on campus. • Bottled water is safer to drink than municipal tap water. • Reusable water bottles are easy to lose or forget at home. • I don’t have access to filtered tap water on campus. • Bottled water is more convenient because it is available in many places on campus. • I feel that the tap water on Purdue’s campus is unsafe to drink.

Heavy users of bottled water tended to be more neutral toward benefits of tap water than non-users of bottled water. However, they tend to agree with the following benefits of drinking tap water:

• Bottled water is much more expensive than tap water. • I don’t have to go to the store regularly to purchase bottled water. • I am contributing less plastic to landfills. • I can reduce my consumption of oil used to make plastics.

This study revealed relatively widespread bottled water consumption at Purdue and identifiedcertain groups (undergraduates and women) who cur-rently drink a disproportionately large amount of bot-tled water. From the results of the survey, a campaign for tap water at Purdue should address the barriers and highlight the benefits of drinking tap water. In his 1999 book, Fostering Sustainable Behavior, Doug McKenzie-Mohr emphasizes that certain tools have been effective at addressing certain types of

barriers, and that social marketers should combine the appropriate tools into cohesive strategies for success-ful campaigns. Table 1 summarizes general catego-ries of barriers and the recommended tools; Table 2, outlines specific strategies to promote tap water based on the barriers and benefits our study uncovered. The premiums Americans pay for bottled water (as much as 10,000 times more than tap water) indicate that they highly value clean drinking water, and may distrust the quality of tap water. Bottled water com-panies want consumers to believe they are paying for safer ‘natural’ water. However, there is little if any evidence that bottled water is safer than tap; in fact, based on the statistics below, it may not be as safe.

• Municipal tap water is subject to more rig- orous standards with more frequent monitoring than bottled water by the U.S. Environmental Protection Agency (EPA). • EPA regulations require reporting (within 24 hours) to the state when a health concern arises from a municipal water supply. There is no requirement for reporting problems with bottled water to the Food and Drug Administration (FDA). • Because there are no official reports of illnesses from bottled water, media attention on problems with tap water has weakened public trust in tap water, while falsely inflating confidence in bottled water. • The FDA only regulates products sold in “inter state commerce,” thus exempting bottled water that is produced and sold within a state (about 60% of bottled water in the U.S.) from federal regulation.

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Photo of numerous example of reusable water bottles varying in color, size, shape, and style.

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Barriers ToolsLack of Motivation If they have intentions to act: Commitments

If they need convincing: Social Norms, Incentives

Forgetting PromptsLack of Social Pressure Social Norms

Lack of Knowledge Communication, Social DiffusionInconvenience Structural/Environmental Changes

Table 1: Types of Barriers and Recommended Tools

Social Norms = expected or typical behavior in societyPrompts = visual displays that serve to remind people to engage in a certain behavior

Respondents generally believed that the environ-mental impact of their individual behavior would be less significant than the global impact of bottled water consumption. Therefore, students, faculty, and staff may be underestimating their individual contributions to the overall environmental impacts of bottled wa-ter. A tap-water campaign would need to help people realize that each individual’s behavior adds to the total impact. The campaign should also account for the fact that women at Purdue currently drink more bottled water than men, and that they were more concerned about the global and individual environmental im-pacts of drinking bottled water. A campaign that urges behavior change based on the individual and global environmental impacts of bottled water may be more persuasive to women than men at Purdue University. Tap water campaign messaging, which should be placed as close as possible to locations where an individual purchases bottled water, should highlight the waste of plastic, time, and money by purchasing bottled water. This could be effective because survey respondents felt that the high cost of bottled water, the time spent purchasing bottled water, and the waste of plastic were key benefits of switching to tap water.

Many of the barriers this study uncovered could be addressed most effectively through structural changes at Purdue. The University could prioritize tap water quality on campus and build trust in safety by updat-ing and improving the tap water infrastructure across campus, especially in older buildings where degraded pipes may cause contamination. Advertising improve-ments would be a key component of building trust in tap water on campus. In addition, Purdue could provide filtered tap water in more places on campus (with modern drinking fountains, for example) and ef-fectively advertise these options. The university could also promote sustainability and save money by no lon-ger providing free bottled water at campus events, and switching to pitchers of tap water. Once trust in cam-pus tap water is restored, the University could make a strong statement in favor of sustainability, following the example of other universities, such as Washington University in St. Louis, by ending the sale of bottled water on campus. For this policy to be effective, it would be crucial to build the support of Purdue stu-dents, faculty, and staff, as well as the dining services, and consider their input before its implementation.

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Barriers and Benefits Tools StrategiesBarriers to Drinking Tap Water:

I don’t like the taste of tap water as much as bottled water (Lack of Motivation, Lack of Knowledge)

Commitments,Communication

Blind taste test, incorporate commitment to drink less bottled

water/more tap water

Bottled water is safer than municipal tap water. Concern about safety of tap water on Purdue’s campus (Lack of Knowl-edge)

Communication Information about regulations, safety of tap water & deception by bottled water companies

Concern with germs in reusable water bottles (Lack of Knowledge)

Communication Inform about simple ways to keep bottle clean. Provide dishwasher-safe reusable water bottle.

Perceived lack of access to filtered tap water on campus (Inconvenience; Lack of Knowledge)

Communication,Structural Changes

Inform: Filtered water is already available in Purdue Memorial Union; several newer water fountains on campus include filters. Increase availability of filtered tap water on campus and

advertise.Reusable water bottles are easy to lose or forget at home (Forgetting)

Prompts Distribute eye-catching refrigerator magnets and/or signs for doors. “Don’t forget your reus-

able water bottle.”Bottled water is offered for free at events and meetings on campus. Bottled water is more convenient since it’s available in many places on campus (Inconvenience)

Structural Change Purdue University policy changes: providing tap water at events instead of bottled. Improv-ing the tap water infrastructure on campus, fol-lowed by a campus-wide ban on bottled water.

Benefits of Tap Water:

Saving money because tap water is much cheaper than bottled water (Provides Motivation)

Communication,Incentive

Inform/persuade: “You’re wasting money and resources on bottled water!”

Don’t have to go to the store regularly to purchase bottled water. A reusable bottle holds more water (Convenience, pro-vides motivation)

Communication “You’re wasting time and money buying bot-tled water. Using a reusable bottle means you don’t have to buy several bottles of water per

day.”It’s better for the environment. Less plas-tic in landfills, less waster of oil. (Have Intentions, Lack Motivation)

Commitments,Communication

“Stop throwing away money, and plastic bot-tles! Drink tap.” Use commitments to motivate those who are aware of impacts but still drink

bottled water. Bottled water is the same or similar to tap water (Motivation, Knowledge)

Social Norms, Communication

Inform about bottled municipal tap water. In blind taste tests, most people can’t tell which is

tap or bottled.

Table 2: Developing Strategies to Promote Tap Water and Discourage Bottled Water Usage

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Emergence Of Green Ash As AResearch Toolby Shaneka Lawson

Green ash (Fraxinus pennsylvanica) is a native North American tree that has been used extensively in the production of solid-wood products such as crates and boxes, and for specialty products, such as tool handles and furniture. These trees have also been planted for timber production and as ornamental trees. Most of the previously published research with this species focused on observations, which did not include gene manipulation, or were based on studies where the trees were monitored in the natural envi-ronment or transferred into greenhouses for closer examination. Climate change will likely affect the abundance and performance of micro- and macro- scopic flora and fauna within forests. Studying the influence of climate change on the developmental morphology of green ash has uncovered more questions than an-swers. As climate change becomes more pronounced, tree characteristics (i.e., root shape, stomatal density, and crown shape) and phenology (i.e., leaf shedding and bud burst) are also being altered. Through my project, I am taking a closer look at the guardians of the soil, the trees, and how climate fluctuations are changing the face of the landscape. The responses of poplar (genus Populus) and green ash to water avail-abilities are the primary focus of my research. Since the publication of a technique for inserting DNA into green ash (a tree that historically had not been manipulated genetically), this protocol has been used almost exclusively in the Pijut lab here at Purdue University. While the genomic sequence for green ash has not been published, the availability of simi-lar DNA sequences from other tree or plant species, such as poplar (currently one of the most widely used model tree species, whose genomic sequence was published in 2006) provides a worthwhile starting point. Although the genomic sequence of poplar has been published, additional information about which genes were present within the sequence has been a sig-nificant undertaking for scientists, and has yet to be completed. In my research, I have taken stomatal

Green ash shoots forming on a piece of stem tis-sue. Formations of these tiny shoots were one of the first signs that the transformation process had been successful, as shoots were being grown on medium

supplemented with antibiotics.

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density gene sequence data from thale cress (Arabi-dopsis thaliana), the most widely used plant model, whose gene sequence has been published, and com-pared its DNA sequences to that of poplar. When a close match was found, I isolated and purified both DNA sequences. This purified DNA was then recon-figured and inserted into the poplar genome, resulting in the production transgenic poplar trees with altered stomatal pore (openings in a leaf that allow for uptake of carbon dioxide (CO2) and release of water (H2O)) densities. While not all genes from poplar will func-tion the same way as the genes from thale cress, when introduced into another tree, it is worthwhile to de-termine if those genes with similar sequences will be expressed and perform the same function in heterolo-gous species. My research looks at a number of events involved with climate change and examines not only the mor-phological responses of poplar but also the physiologi-cal responses. By using genetically engineered poplar lines that have different numbers of leaf stomata, I have been able to examine whether a change in the number of stomata will influence the amount of water up-take by the tree without diminishing its biomass

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Transformed poplar plants: The photo on the left is a transgenic poplar plant carrying a stomatal density alter-ing gene from Arabidopsis. On the right are Magenta boxes containing a number of transgenic poplar lines

carrying a gene from poplar thought to behave in a similar way as the stomatal density gene from Arabidopsis.

(the total organic material of a plant) production, a phenomenon known as water-use efficiency (WUE). I hypothesized that an increase in WUE would not only greatly reduce the amount of water needed for trees to grow but would also mitigate some of the negative effects of drought, thus improving drought-tolerance of the tree. I have also examined stomatal conductance rates, or the speed at which water is transpired (released in a gaseous form) from the stomatal pores, in all of my transgenic poplar lines and recorded data for those lines which exhibit a variation from the wild-type, or untransformed plant. Results show that those plants with unusual values with respect to stomatal number also exhibit observable modifications other than sto-matal density, such as changes in root morphology, a presumed sign of increased drought-tolerance. The transpiration data gathered to date have con-firmed that transgenic plants expressing the candidate gene I identified does influence the stomatal patterning and development in poplar trees, as was seen in thale cress plants. This effort is the first reported example, to my knowledge, of a stomatal regulatory gene from thale cress being used to affect stomatal density in poplar trees. In addition to this being a groundbreak-ing discovery, the information obtained from poplar will be used to generate transgenic green ash trees, a valuable fine hardwood.

By using a newly developed staining technique, stomata can easily be identified and counted. In many tree species, stomata can only be found on the under-side of the leaves (abaxial side); however, in a number of poplar genotypes, both sides of the leaves pos-sess stomata. The average number of stomata varies between each genotype (an individual with an unique gene sequence) of poplar trees. Therefore, numerous samples must be taken from many transgenic lines to determine if observed results are significant.

Transformed green ash shoots: The photos on the left are of two young transgenic plants, while the photo on the right shows an older shoot ready to be transferred

into rooting medium before being moved to a pot in the greenhouse.

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High quality stomatal staining technique: The clear differences in stomatal density were indi-cated in the contrast between the photo on the left and the one on the right.

Thus far, my results indicate that manipulations of stomatal density helps poplar trees survive under drought conditions. Although transgenic green ash trees are not yet large enough to be tested, I anticipate seeing a similar trend in green ash with respect to WUE and drought-tolerance. A green ash tree ex-hibiting increased tolerance to drought would prove beneficial to reforestation and afforestation efforts, as the trees would be able to undergo more aggressive growth even when water availability was limiting. With the predicted improvements in drought-tolerance expected to be seen in green ash, the pos-sibility remains that the drought-tolerance capabili-ties of other ash species (e.g., white, black, blue, and pumpkin) may also be enhanced. Thus, the findings of this research are not limited to poplar and green ash. Homologs of the genes tested in this project could be isolated from other tree species, in turn providing a means of enhancing their drought-tolerance. As available water supplies dwindle, trees exhib-iting the ability to grow using less water will prove advantageous to future genetic research and potential forest tree improvement strategies. This research will

serve to benefit research scientists, farmers, lumber-men, and tree enthusiasts who eagerly await the devel-opment of new techniques for conserving water in for-est plantations or on lands unable to provide the ample soil moisture to sustain current non-transgenic tree growth. Subsequent research into drought-tolerance or WUE may uncover additional genes responsible for other aspects of the drought response. Because climate change is likely to lead to more extreme weather patterns, researchers are motivated to expand the current limits of abiotic stress toler-ance. The research presented here provides a glimpse into the potential for tree engineering in the future. With additional techniques that are currently under development, other more dramatic and perhaps more effective ways of responding to climate change can be attempted.

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Catching the Drift: Environmental Awareness and Attitudes of Commercial Pesticide Applicatorsby Adam Reimer

In the Midwest, agriculture dominates our land-scape. While giving the region a distinct character, agriculture causes environmental damage as well. Pesticides and fertilizers can run off into local wa-terways; critical wildlife habitat can be destroyed to make way for crops; farm equipment, if not properly maintained or updated, can contribute to rural air pollution. The Natural Resources Social Science lab in Purdue University’s Department of Forestry and Natural Resources (FNR) has been working hard to understand behaviors that can lead to environmental damage. Much of this work has focused on farmers and rural lands managers to understand their aware-ness of environmental issues, their general attitudes toward the environment, and what environmentally responsible behaviors they are already undertak-ing. By understanding the decision-making process of farmers, we get a better sense of how to change behavior to improve local and regional environmental quality. Despite the majority of the Midwest being under private ownership, many people besides just the land-owner can have an impact on environmental quality. One of the more concerning forms of rural pollution is pesticide drift. Drift refers to the unintentional

movement of pesticides from a target area to some other place. Pesticide drift can be responsible for un-intended loss of crops, especially sensitive crops like vegetables; damage to livestock; death of honeybees; and water pollution. While farming makes up a large share of total pesticide application in Indiana, pesti-cides are used in other settings as well, primarily by commercial applicators. Pesticides are also applied in industrial settings, on golf courses, to help restore natural areas, and to maintain utility rights-of-way. Drift can occur in any of these settings. To try reducing pesticide drift in Indiana, the Of-fice of the Indiana State Chemist has established a program called Driftwatch. This voluntary program uses an online database to connect commercial and agricultural pesticide applicators (individuals who apply pesticides) with owners and managers of sensi-tive areas (i.e., those properties with crops or ground-cover that might be negatively impacted by pesticide drift). The Driftwatch database allows managers of sensitive areas to locate their property on a map and upload details about why they are sensitive to drift. Applicators can then go online as they prepare to ap-ply and identify sensitive areas near their site. Ap-plicators and sensitive-area managers can also sign up to receive email alerts notifying them of changes in their area, so as new sites come online, applica-tors receive instant notification. The hope is that this new resource will provide better real-time informa-tion to applicators and lead to better environmental outcomes. Despite this hope, researchers and policy makers do not have a firm grasp of the environmental behavior of individuals who apply pesticide. In order to fill this research gap, we worked with the Office of the Indiana State Chemist to survey all commercial applicator license holders in the state. Underlying our research is the theoretical proposi-tion that environmental behavior is preceded by other factors, including knowledge, awareness of the issue, and attitudes about the environment. The survey we designed asked pesticide applicators about their opin-

Photo taken from the driftwatch website show-ing a driftwatch awareness sign placed in a

tomato field.

Photo By Ben Alkire

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14ions on general environmental issues and their aware-ness of pesticide drift. In order to gauge their current behavior, we asked applicators whether they were aware of several commonly accepted practices that reduce pesticide drift and how many of those practices they were currently using. We also asked them what benefits these practices had and what potential barriers stood in the way of using these practices. In addition to these questions about beliefs and behavior, we also asked a series of questions about the Driftwatch pro-gram. Hopefully, the answers to these questions will help improve the program and the online database’s usefulness. We conducted our survey using two methods, a traditional paper copy that we mailed to the applicator, and a link to an alternate online version. The online version was popular; over half of our responses were completed online. We had a strong response to our survey, with over 60% of applicators returning com-pleted surveys. The preliminary results have been encouraging. Applicators indicate a strong awareness and concern for the environment in general. Some of the most positive responses were to questions about personal responsibility to the environment, includ-ing strong agreement with the statements: “Humans must live in harmony with nature in order to survive”, “Individuals have the ability to impact environmental quality”, and “It is my personal responsibility to help protect environmental quality”. Respondents did not seem overly concerned about pesticide drift in general, indicating that the impacts of drift rank between “not a problem” and “slight problem”. It is important to note here that this survey is only assessing the perceptions of pesticide applicators. We do not know the extent of actual damage related to pesticide drift in Indiana. Despite this uncertainty, it is important to understand the perception of the impacts among people who apply pesticides, as this could potentially influence applica-tor behavior. Among the most important questions on the survey

were those related to behavior. Prior to this survey we did not know how many operators used well-ac-cepted drift-reduction practices. This survey indicated high awareness and adoption of several key practices, including decreased application speed, increased spray droplet size, regular inspection of spraying equip-ment, lowered spray boom height, and low-drift spray nozzles. All of these practices were adopted by over 85% of our respondents, which bodes well for reduced pesticide drift. Other practices had lower adoption rates, including the use of specialized spraying equip-ment like band and tunnel sprayers, and the use of websites like Driftwatch to learn about sensitive areas. Applicators had lower awareness of practices with low adoption rates, indicating the potential for education as a way to increase their use. Applicators were largely aware of the Driftwatch program, with nearly 60% of respondents having heard of the website and nearly 40% having used it to inform spraying decisions. There is still room for improvement however; only a quarter of respondents knew they could receive automated email alerts, and only 5% were taking advantage of this option. In addition to the questions we asked, we also elicited comments from survey respondents. A number of these comments may potentially be useful for improv-ing the program and the functionality of the website. Many applicators asked for more up-to-date informa-tion, better maps of sensitive areas, and more informa-tion about sensitive sites, so that they can plan their applications accordingly. Overall, the response to the program appears strong. As a group, pesticide appli-cators seemed concerned about environmental quality and willing to adopt spraying equipment and practices that reduce drift. Understanding the variety of beliefs and behaviors of this diverse group is necessary to guide future efforts to protect Indiana’s environment. For further information on the Driftwatch program, please visit its website at www.driftwatch.org.

Photo From DriftWatch Website

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Foliar Herbicide Control of Boxelder (Acer Negundo)by Matt Kraushar, Zachary Lowe, & Harmon Weeks, Jr.

vegetation management. For example, Integrated Vegetation Management (IVM) utilizes several ap-proaches such as the use of mechanical tools (e.g., chainsaws, mowers, hatchets, etc.); herbicides; natu-ral processes (e.g., prescribed fire, drought, flooding, etc.); or biological control agents (i.e., the release of organisms that target a particular species) to enhance the control of undesired species. Furthermore, differ-ent tools or techniques may be required at different stages of development or spread. Early in coloniza-tion, plants are small in size and their numbers are easier to control. Long after establishment, the num-ber of plants in the population is greater and they are larger, therefore, they are more difficult to control. We tested 16 herbicide tank mixes, which are commonly used for industrial vegetation manage-ment, to determine if any were effective at control-ling boxelder via foliar application. The test site was located on the Indiana Department of Transportation (INDOT) right-of-way (ROW) along the west lanes of Interstate 65 (southbound lanes) in two separate locations between the Wabash River and State Road 26 (mile markers 176.5 and 174.5). The northern-most location contained two of the three replications (groupings required for statistical analysis and in case of uncontrollable errors) and was one-quarter of a mile in length. The southern site was located at the end of the entrance ramp from State Road 25 onto southbound I-65; it was one-eighth of a mile in length. The trees were located from the edge of the borrow ditch extending up an east-facing slope. Veg-etation under the trees consisted of a mixture of grass and herbaceous broadleaves. The soils were com-prised of clay glacial till. As a result of roadbed and ROW construction; soils were heavily compacted, limiting water penetration. The trees ranged in size from 5-8 inches in diameter at breast height (DBH) and from 12-20 feet in height. Vegetation manage-ment practices by INDOT in these areas were mini-mal as a result of the ditch and the steep slope, where the trees were present. The herbicide treatments were applied on August 1, 2008. Each of the 16 tank mixes was sprayed on

Invasive woody plants are non-native species that are weedy in nature (i.e., they tend to be prolific seed producers, re-sprout from roots, and form dense colo-nies). Even though exotic or introduced species may be invasive in nature, many native species also can have invasive characteristics. Such species, whether native or exotic, pose a threat to natural communities when a natural check is not in place. Many environ-ments are heavily degraded and altered by humans, thereby eliminating natural checks. These conditions can result in increased spread and growth of undesir-able, invasive species. Boxelder (Acer negundo) is a native species which can form dense colonies. It is often referred to as a weedy or invasive species. The invasive nature of boxelder has the potential to alter both wildlife species composition and recreational use of an area. Another concern is its prevalence along roadsides, because as the trees grow, limbs may extend into the travel lanes. Furthermore, both the limbs and the en-tire tree have the potential to fall during ice storms or high-wind events, which can endanger motorists, and requires removal. Boxelder has a high propensity for root suckering and re-sprouting when the main stem is cut. Basal bark (application of an herbicide mixture to the base of a woody stem extending to 12 inches from the ground) and cut surface (application of an herbicide mixture to the cut stump) herbicide applications are an effective means of controlling woody species by minimizing re-sprouting. However, one of these treat-ments requires cutting the stem and has the potential to cause the tree to fall into the roadway. Addition-ally, removal of the cut portion along a busy road can be hazardous to workers. Due to these safety concerns, foliar herbicide treatments (application of herbicides to the leaves of a plant) may provide an effective alternative, as they are typically done from the safety of the spray vehicle. However, an effective foliar treatment has not been developed for boxelder to date. Controlling invasive species often requires a multi-tiered approach, and there are several forms of

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three blocks comprised of three individually tagged trees per block. A total of 153 trees were tagged to produce 51 groups of three trees each. The groups of three were assigned a number (1-51) and were randomly divided into three treatment blocks of 17. Treatment blocks 1 and 2 were located in the north-ern parcel, while block 3 was located in the southern parcel. Both locations were similar with respect to aspect, and tree size and location on the slope. The herbicides were mixed with water to achieve a 50 gallon per acre application rate (at 35 psi) using a 4-gallon stainless steel CO2-pressurized, backpack sprayer. A standard roll-over nozzle outfitted with two different nozzle types was placed on the end of a 10-foot section of ¼ -inch aluminum pipe, in an effort to reach the heights necessary to spray the foliage of the boxelder trees. The foliage was sprayed to the point of wetting but not to runoff. Percent defoliation and other symptoms such as leaf color and development, re-sprouting, and slough-ing of bark (bark falling off of tree) were recorded at 30 days (September 2008) after treatment (DAT). Defoliation ratings were taken by visual estimates of the percentage of defoliation in relation to untreated trees. In addition, percent mortality was taken at 365 DAT. Mortality was defined as a stem that no longer produced any leaves (i.e., 100% defoliation with no resprouting). All values were averaged by treatment across blocks, because no outliers were observed. Note that outliers were considered to be individual trees that did not exhibit the same symptoms as the other trees treated with each mixture. Success of a treatment was ranked by percent mortality of trees

sprayed with a single mixture, and this ranking was used to determine the most effective treatment.

Results after first growing season

At 30 DAT, the untreated controls (trees that were not treated with an herbicide to serve as comparisons of what healthy trees should look like) showed no greater than 3% defoliation and the leaves throughout the tree canopies were predominately green and begin-ning to senesce. No premature leaf abscission (leaves falling off of tree) or senescence (drastic color change due to aging leaf) was observed. None of the mixtures caused 100% defoliation at 30 DAT. Percent defoliation ranged from 20% for the Open-sightTM herbicide treatment to 84% for the Arsenal PowerlineTM + AccordTM herbicide treatment. Leaves were brown and curled in all treatments. The upper reaches of the tallest trees of a few treatments ap-peared not to have been treated, possibly due to ap-plicator error.

Results after second growing season(one year after treatment)

At 365 DAT, the untreated controls showed no mor-tality and no changes in leaf health, tree canopy size, or tree form (shape) at the time of treatment. Several treatments resulted in 100% defoliation. All treated trees, including individuals that had appeared to be untreated or not affected in the upper reaches in the first growing season. Percent defoliation ranged from 53% in the OpensightTM + Remedy UltraTM treatment

The map on the left shows the northern treatment location, while that on the right shows the southern treatment location. Herbicide treatments were applied to individual trees located within the areas

outlined in red.

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Percent DefoliationProduct Rate (mL/acre) Sept. 2008 Sept. 2009

Forefront R&P (aminopyralid +2,4-D) 946 30 65

Forefront R&P (aminopyralid +2,4-D)Remedy Ultra (triclopyr)

946946

33 77

Forefront R&P (aminopyralid +2,4-D)Remedy Ultra (triclopyr)

9461420

53 93

Opensight (aminopyralid+ metsulfuron methyl) 79 52 68

Opensight (aminopyralid+ metsulfuron methyl)Remdy Ultra (triclopyr)

79946

63 68

Opensight (aminopyralid+ metsulfuron methyl)Remedy Ultra (triclopyr)

791420

47 53

Remedy Ultra (triclopyr) 946 63 55

Opensight (aminopyralid+ metsulfuron methyl) 1562 20 83

Crossbow (triclopyr +2,4-D) 3785 57 70

Milestone VM Plus (aminopyralid) 4259 60 86

Arsenal Powerline (imazapyr)Accord (glyphosate)

4373785

84 99

Arsenal Powerline (imazapyr)Tordon (picloram)

437946

33 100

Arsenal Powerline (imazapyr)Milestone VM (aminopyralid)

437207

30 100

Arsenal (imazapyr)Accord (glyphosate)

4373785

77 100

Arsenal (imazapyr)Tordon (picloram)

437946

27 98

Arsenal (imazapyr)Milestone VM (aminopyralid)

437207

27 95

Table 1: Observed effects of 16 tank mixes for two growing seasons following treatment.

to 100% for herbicide treatments containing Arsenal PowerlineTM + TordonTM, Arsenal PowerlineTM + Milestone VMTM, and ArsenalTM + AccordTM. Trees treated with Arsenal PowerlineTM + AccordTM, Arse-nalTM + TordonTM, andArsenalTM + Milestone VMTM retained 5% or less of their original foliage (i.e., 95% or greater defoliation). All herbicide treatments that

included imazapyr (Arsenal PowerlineTM or Arsen-alTM) reduced re-sprouting by 70% or more. The only other treatment to produce greater than 90% mortality was Forefront R&PTM + Remedy UltraTM. Most ROW managers consider Boxelder a species that is difficult to kill. Trees treated with herbicide commonly appear to die during the first growing

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18treatment yielding 100% mortality, whereas the treat-ment containing ArsenalTM resulted in 95% mortality. The other tank mixes that produced 95% or greater mortality are probably not appropriate for ROW spraying. The addition of AccordTM (glyphosate), which is nonselective, kills grasses, and TordonTM (picloram), which is more toxic and mobile. Highly compacted soils can increase the amount of runoff, so the use of a compound such as picloram, with higher mobility and longer half-life (the length of time it takes for half of the product to be chemically degraded), should be limited in use near ditches and waterways. The trees used in this study were large specimens having stem diameters of 8 inches DBH and heights of 20 feet; therefore, smaller trees should also be susceptible to mixtures of Arsenal PowerlineTM and MilestoneTM. Debris, such as fallen limbs and main stems, can be hazardous when driven over by mow-ing crews. Thus, targeting smaller trees would help eliminate the need to cut and remove dead material, because debris resulting from them tends to decom-pose more quickly than that of larger trees. Foliar herbicide applications are not the only tools available to control boxelder; however, the tank mix of Arsenal PowerlineTM and MilestoneTM produces very good results, should minimize damage to under-story grasses; and can be used when other manage-ment options, such as mechanical cuttings, biological control, and natural processes are not safe to use or are unsuitable for the site. The effectiveness of this mixture should be considered when formulating an IVM plan for the control of boxelder. However, this mixture must be used with caution when desirable broadleaf species are present, because it is highly ef-fective on most broadleaf species, even one year after treatment, as a result of residual activity of the active ingredients.

season but show little injury the following year. The most expensive vegetation management practice is one that needs to be done twice, regardless of method. Multiple herbicide applications on roadside ROWs are not only more costly but also expose workers to additional roadside hazards. It is important to consid-er worker safety when determining what vegetation management option to use. Utilizing a foliar-applied herbicide that provides high levels of control with just one treatment is one way of reducing costs and keep-ing workers safe. Our study indicated that treatments containing imazapyr resulted in high mortality rates (at least 95%). Imazapyr is a widely used herbicide that results in good levels of control when used for both foliar and cut-surface treatments. However, some species can be tolerant and/or be slow to react when treated with imazapyr alone. Applying it in combina-tion with other herbicides helps ensure control of a wide variety of species. The most effective combina-tions of this study are some of the most commonly used tank mixes for woody plant control in ROW. The less effective tank mixes can provide good control of some species, but their efficacy on other difficult-to-control species are still being evaluated in other, ongoing investigations. Imazapyr has very low toxicity in organisms other than plants, because it works by affecting a plant-specific enzyme. Furthermore, imazapyr, when used as a foliar application on woody species, has little effect on grasses growing in the treated area, which are crucial for erosion control. Incorporating an ad-ditional herbicide to broaden the spectrum of species controlled, while retaining selectivity (affecting only targeted plant species or plant group) and low toxic-ity (of non-target organisms) is an important aspect of roadside and natural area vegetation management. Of the treatments incorporated in these trials that resulted in 95% or greater mortality, two fit these require-ments: Arsenal PowerlineTM (imazapyr)+ MilestoneTM

(aminopyralid) and ArsenalTM (imazapyr) +Milestone aminopyralid). The difference between Arsenal Pow-erlineTM and ArsenalTM is the inclusion of Transport TechnologyTM in Arsenal PowerlineTM. According to the BASF Corporation, Transport Technology is proprietary and increases the amount of absorption and movement of active ingredients within the plant. A small difference in control was observed between these two treatments, with the Arsenal PowerlineTM

19

Northern slimy salaman-ders (Plethodon gluti-

nosus) are the third most-commonly encountered

woodland salamander in our study.

Photo Provided By Jamie MacNeil

Although often overlooked by the casual observer, woodland salamanders are thought to be the most abundant vertebrates in eastern US forests. These small, cryptic amphibians spend much of their time underground or under rocks and logs, and emerge at night during cool, wet weather, to forage among the leaf litter. Woodland salamanders differ from pond-breeding salamanders in that they mate and lay eggs in moist microhabitats of the forest rather than mak-ing annual migrations to wetlands to breed. Woodland salamanders are ideal indicators of for-est ecosystem health, because they serve an important role in these ecosystems and are sensitive to environ-mental change. They may look small to us, but in the realm of soil organisms they are top predators, regu-lating populations of invertebrates. By eating these small prey, salamanders make the nutrients within them available to larger predators, such as snakes, small mammals, and birds, which cannot efficiently survive on invertebrates alone, but find salamanders to be a convenient snack. The impact of salamanders in nutrient cycling and regulating soil organisms is enhanced by their sheer numbers; density estimates exceed two per square meter in some eastern forests. Not only do woodland salamanders play an important role in the ecosystem, they also respond acutely to al-terations of their habitat. Their sensitivity to changes in the environment derives partially from their lack of lungs; woodland salamanders breathe entirely through their skin. This requires them to remain in cool, moist microhabitats, such as wet leaf litter, un-der fallen logs, or in the burrows of other animals to avoid drying out. Most species maintain very small home ranges of one to two square meters, and they are thought to be

poor dispersers, with a limited ability to move to new habitat following a disturbance. Due to their impor-tant function in forest ecosystems and their sensitiv-ity to environmental changes, woodland salamanders have been used to monitor forest health following disturbances, such as fire, logging, and development. However, the effects of forest management on these species are still not well understood. We are seeking to determine how different for-est management techniques affect the health of forest ecosystems by studying the abundance and species richness of woodland salamanders. We are also investigating the edge effects of clearcuts (i.e., complete removal of the forest canopy) on salaman-ders, by determining how salamander abundance and species richness vary across a gradient from the forest interior to the edge of a recent clearcut and to the clearcut interior. Our study takes place in Morgan-Monroe and Yellowwood State Forests in south-central Indiana, within the framework of the Hardwood Ecosystem Experiment (HEE), a 100-year collaborative project enacted by several partners across the state, including

The Effects Of Timber Harvest On Woodland Salamandersby Jamie MacNeil

Forestry & Natural Resources

Timber harvests create drastic contrasts between open habitat and closed-canopy forest, as shown at the edge of this recent clearcut. We use clearcuts to study edge effects, which are the impacts that

one habitat (clearcut) exerts on an adjacent habitat (closed canopy forest) at their border.

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20Purdue University. The HEE examines three forest management techniques: 1) even-aged management (clearcuts and shelter woods); 2) uneven-aged man-agement (single-tree and group selection); and 3) uncut control. Nine 200-acre study areas within the two state forests have each been assigned one of these three management types, with three replicates of each type. We monitored the woodland salamander community before harvests were implemented and are continuing to do so afterward. To monitor woodland salamanders, we placed arrays of artificial cover objects (ACOs) in a grid pat-tern of 30 boards (30.5x30.5x5 cm) each throughout the nine study areas. ACOs mimic natural debris on the forest floor and create attractive micro-habitat for woodland salamanders, providing a way for us to sample salamanders that does not destroy existing habitat and is cheaper and less labor-intensive than other methods. Prior to the implementation of timber harvests, 66 of these ACO grids were placed in the forest, both inside and outside areas designated for harvest. We checked these for salamanders every-other week during the pre-harvest sampling interval from September to November 2007 and from March to May 2008. We continued to monitor these and an additional 18 ACO grids (for a total of 84 grids) dur-ing the post-harvest sampling interval, every March through May and September through November, starting in 2009 and continuing to the present. To study the effects of clearcut edges on forest

ecosystem health, we placed additional ACO grids at six distance intervals across the interface of a clear-cut and the adjacent forest. These smaller grids of 24 boards each were placed at the edge, at 20 and 40m from the edge into the clearcut, and at 20, 40, and 60m from the edge into the forest. This design was replicated at each of the six clearcuts, for a total of 864 additional ACOs. For these “edge” grids, we not only recorded the number of salamanders under each board, but also the snout-vent length (SVL), mass (or weight), and sex of each individual. At two of the clearcuts, we also marked each individual with visible implant elastomer (VIE), a new technique we developed to record and generate lists of marks using a computer program, SalaMarker (download available at http://web.ics.purdue.edu/~rodw/Publica-tions.html). These unique marks will provide a better estimate of abundance of woodland salamanders in our study areas. Salamander activity is strongly influenced by envi-ronmental factors such as precipitation and tempera-ture, so we use records from National Oceanic and

MS grad student Jamie MacNeil holds an artificial cover object (ACO) made of solid pine. ACOs create moist microhabitats that attract woodland salamanders and provide

a cheap and effective means of sampling these secretive animals.

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An eastern red-backed salamander (Plethodon cinereus, left) and a northern zigzag salamander (Plethodon dorsalis, right). Together these two species comprise almost 95% of all salamander

encounters in this study.

Forestry & Natural Resources

21and Atmospheric Administration (NOAA) co-op sta-tions to obtain daily data on these parameters. We also collect data on the amount of downed woody debris at our ACO grids. At the “edge” study sites, we collect data on soil moisture, canopy cover, and leaf-litter depth for each grid, while digital, tempera-ture data loggers record hourly temperatures near-ground level and under cover objects. The collection of these habitat data will help us determine if there is a link between the abundance and species diversity of salamanders to the health of the ecosystem. So far, the study has yielded over 18,000 sala-mander encounters representing nine species. The most commonly encountered species are eastern red-backed (Plethodon cinereus) and northern zigzag (Plethodon dorsalis) salamanders. Together these species make up almost 95% of all of our salamander encounters. We are still collecting data, but trends between the pre- and post-harvest sampling periods are already emerging. Preliminary results indicate decreased en-counter rates of woodland salamanders on sites where clearcuts and group-selection cuts (which remove most of the canopy) were used, while there was an in-crease in salamander encounters in adjacent forested areas. However, lower encounter rates do not nec-essarily mean that the salamanders in the cuts have died. The lower encounter rates could also be caused by salamanders: 1) moving to new a habitat, 2) re-treating underground, or 3) preferring to use newly felled logs rather than our artificial cover objects. Further study is required to determine which of these options is responsible. Our data also indicate that various species may respond to forest management differently. For example, encounters with red-backed salamanders decreased following clearcutting while encounters with zigzag salamanders increased. We will be analyzing our data to see if these preliminary trends hold, and investigate how the other environ-mental variables might influence our results. Our data on edge effects reveal a slight increase in salamander encounters across a gradient from the clearcut interior to the forest interior on southwest-facing slopes. On northeast-facing slopes, encounters with red-backed salamanders do not vary across this edge gradient, while encounters with zigzags increase from the forest interior to the clearcut interior. This suggests that northeast-facing slopes, which receive less sun than southwest-facing slopes, may

buffer the effects of clearcuts on salamander activity. Additional, fine-scale measurements taken at these sites will help us determine whether salamanders differ in size or sex among distance intervals, and our use of VIEs on a subset of these sites will give us bet-ter estimates of abundance. The large-scale nature of this study (which spans 31 kilometers and 3,600 hectares), coupled with the collection of pre- and post-harvest data within an experimentally manipulated forest landscape, sets this study apart from previous investigations into the ef-fects of forest management on ecosystem health. Our results will help inform forest-management decisions and improve our understanding of the relationship between these cryptic species and their environ-ment. By understanding how woodland salamanders respond to various timber-harvest techniques, we increase our ability to balance the forest-management goals of maintaining a healthy ecosystem while also producing timber.

A woodland salamander marked with orange and yellow visible implant elastomer (VIE).

The fluorescent dye is injected under the skin, where it becomes a pliable solid. Different combinations of colors and body locations

provide unique identifying marks, which allow for a better estimate of population size.

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Worldwide water shortages are increasingly becoming a major factor limiting crop production, threatening both our health and economic well-being. According to the World Bank, approximately 80 countries are presently experiencing water shortages. With urbanization continuing to spread and reduce arable (or suitable) cropland availability, some crop production is shifting to more arid sites. This shift has, in turn, affected productivity, because many crops are maladapted to these new environments. For example, China’s economy suffers an estimated yearly economic loss exceeding 25 billion dollars, primarily resulting from water shortages negatively affecting rice production. With oil prices soaring in the U.S., it is easy to overlook something as basic as water availability, especially with the recent flooding in the Midwestern U.S. However, in many countries; water shortages greatly impact crop production. The U.S. is not im-mune to this problem, with many southwestern states, such as Arizona, Nevada, Texas, and New Mexico experiencing droughts, which have led to record-breaking wildfires. In an attempt to replace petroleum, fuels from re-newable sources (such as wind, water, and solar) are increasingly being sought. In recent years, Congress and various federal agencies have set specific goals for increased production of fuels from renewable sources, resulting in increased demand for natural resources such as water and arable land. The U.S. Department of Energy has set a goal of replacing 30% of our liquid transportation fuels with those derived from renewable sources by the year 2030. Many states have also begun to set Renewable Portfolio Standards (for more details visit: http://apps1.eere.energy.gov/states/maps/renewable_portfolio_states.cfm); most requiring at least 25% of their total energy consumption to come from renewable sources by the year 2025. To meet this challenge, a suite of energy crops will need to be grown in large, dedicated plan-tations. Such an undertaking will result in a greater demand for natural resources, particularly water and arable land. In order to avoid displacing agronomic

crops (corn, soybeans, cotton, etc.) from the land on which they are currently grown, dedicated bioenergy crops can be engineered to grow on marginal land that is not suitable for food and feed production. Not only will water be needed to grow these bioenergy crops, it will also be required to process the biomass feedstock while during ethanol produc-tion. Current technology requires approximately 3 to 4 gallons of water for every gallon of ethanol pro-duced. Therefore, efforts to grow and process enough biomass to meet the increasing demand for biofuels will become an additional threat to our limited water supply. Two important qualities for a biomass crop are its ease of propagation and rapid growth. For these and many other reasons, poplars (species within the genus Populus) have recently received much attention as a potential bioenergy crop. Poplars, however, are adapted for growth in water-rich environments and, as a result, do not generally use water very efficiently. Unless something can be done to improve their utili-zation of water, they will not be suitable for growth on dry, marginal land. Water is perhaps the greatest constraint to plant growth, in both food and woody crops. Stomata are

Transforming Populus In Order To Increase Water-Use Efficiencyby Matthew Caldwell

Trees are engineered in a sterile environment within the laboratory prior to being trans-

planted into the greenhouse.

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pores through which leaf gas (e.g., carbon dioxide and water vapor) exchange occurs. Approximately 97% of the water absorbed by the plant is lost to sto-matal transpiration (the loss of water from the plant through evaporation). Stomatal aperture (pore diam-eter) affects not only the rate of transpiration, but also photosynthesis (the process of converting light energy to chemical energy) and mineral transport throughout the plant’s cells. Therefore, regulation of stomatal function is considered to be a vital adaptive mecha-nism in drought response.

As a result of water stress, increased presence of Abscisic

Acid (ABA) causes the sto-mata to close. This reduces the

amount of water leaving the plant. However, it also limits

the amount of carbon dioxide, which is necessary for growth,

entering the plant.

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My research is involved in limiting stomatal wa-ter loss by manipulating the aperture of the stomatal pores. This can be done by altering the synthesis (or production) of abscisic acid (ABA), a phytohormone (chemical which influences plant tissue growth and development). Elevated ABA levels in the guardcells, which form the stomatal opening of a plant, regulate the plant’s response to low water availabil-ity by triggering stomatal closure. Previous research has shown that a reduction in stomatal aperture can reduce water loss, while leaving the carbon dioxide uptake level relatively unchanged. This is because rates of diffusion of carbon dioxide and water vapor are affected differently as the stomatal opening be-comes restrictive. For this reason, it is believed that a moderate increase in the amount of ABA produced by a plant will reduce the amount of water lost, while having a negligible effect on the rate of photosynthe-sis and biomass accumulation (growth of new tissue). This may be an effective strategy for many species,

Over the course of several months, transformed cells are regenerated into whole new plants.

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24because all terrestrial plants have stomata. To study the effect of increased ABA concentra-tion on stomatal function and transpiration, I have utilized a laboratory technique in which bacteria are used to insert a gene whose expression alters the rate of ABA production within the plant. The ultimate goal is to engineer a line of Populus that produces enough ABA to induce sufficient stomatal closure to decrease transpiration, but lead to greater water-use efficiency (i.e., the volume of water needed to pro-duce a given amount of biomass). Hopefully, this change will allow poplars to not only survive on more water-restrictive lands, but also to maintain their rapid growth rates. At present, transformed trees (i.e., trees in which a new gene has been inserted) have been regenerated and are growing in a greenhouse. I am conducting experiments to evaluate their drought tolerance, tran-spiration rates, endogenous (internal) ABA concentra-tion, and stomatal aperture. Preliminary data show that some genetically altered lines may indeed exhibit reduced levels of transpiration. After further testing in the greenhouse, these lines will then be grown at the FNR Farm (a research property owned by Pur-due University’s Department of Forestry and Natural Resources) to evaluate their performance under field conditions. If effective, this technology may allow these rapidly growing trees to produce biomass in a sustain-able manner on more arid lands without sacrificing productivity. Their ability to thrive on marginal land may allow high-quality farm land to be left for grow-ing food and feed crops, while having sufficient space on less suitable land for the growth of large, dedicated energy plantations that will be needed to meet soci-ety’s increasing demand for renewable fuels.

Regenerated trees are evaluated to ensure proper transformation.

Photo Provided By Darla French

Forestry & Natural Resources

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Photos by Tom CampbellMartell Forest is a 425 acre facility that consists of native forests, plantations, and the J.S Wright Forestry Center which supports the department’s research, conference, and teaching needs.

PURDUE AGRICULTURE

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Originally built in 1901, Pfendler Hall became the primary home of the Department of Forestry and Natural Resources in 2004 after a major renovation and addition.

Purdue University is an equal access/equal opportunity institution.