restoration of invaded grasslands in a changing...
TRANSCRIPT
Restoration of invaded grasslands in a changing world: Impacts of
invasive plants and climate change on ecosystem functioning
Johannes Kollmann1, Florencia Yannelli1,2 & Leonardo Teixeira1,3
1Chair of Restoration Ecology, Technical University of Munich, Germany
2Centre for Invasion Biology, Stellenbosch University, South Africa
3Center for Biosciences, Federal University of Rio Grande do Norte, Brazil
SER Europe Summer School on Ecological Restoration, 20.–24.08.2018, Vacratot
2
Why ecological restoration?
… because of climatic challenges for biodiversity and ecosystem functions
3
WarmingDrought
htt
p:/
/i.
tele
grap
h.c
o.u
k
Hurricanes
Salinisation
ww
w.f
oo
dn
avig
ato
r.c
om
… due to land-use changes affecting biodiversity and ecosystem functions
4
FragmentationEutrophication
Biological invasions
Habitat lossesDiseases
Pollinator losses
… because of environmental sustainability on a cultivated planet
Foley et al. 2011, Nature 5
… for securing natural resources and environmental sustainability
Foley et al. 2011, Nature 6
Contributions of ecological restoration?
… for securing natural resources and environmental sustainability
Introduction 7
8
Why grassland restoration?
… because of their biodiversity and ecosystem functions
Veldman et al. 2015, Science 9
• Grasslands cover 40% of all terrestrial biomes
• Ecological value: species richness, erosion control, groundwater production, carbon sequestration
• Economic value: livestock grazing, food production
• Subject to increasing land-use change (conversionto arable land, afforestation, urbanisation)
… because of land-use changes resulting in grassland losses
Zerbe & Wiegleb 2009, Renaturierung von Ökosystemen 10
1954 1992
11 km
Reduction of grassland area near Münster in NW Germany
–44% area and +67% number of patches
… because of the dynamics of grassland degradation and restoration
Andrade … Kollmann et al. 2016, Brazilian Journal Nature Conservation 11
… because of research opportunities of grassland restoration
Kollmann et al. 2016, Restoration Ecology 12
Under-investigated in restoration studies:
Invertebrates
Microbes
Carbon sequestration
Decomposition
13
Why addressing invasive alien plants?
… because of threats of invasive species to the functioning of ecosystems
Invasive alien species (IAS) are the second most important threat to biodiversity
IAS can change plant community composition in the long term
Ehrenfeld 2003, Ecosystems; Batten et al. 2006, Biological Invasions; Ehrenfeld 2010, Annual Review of Ecology, Evolution, and Systematics; Vilà et al. 2011, Ecology Letters; Trentanovi et al. 2013, Diversity and Distributions 14
Ailanthus altissima
Hulme 2013, New Phytologist 15
… because enhanced invasions under climate change
Neophytes respond faster and stronger to climate change
Native: Impatiens noli-tangere
Alien: Impatiens parviflora
Example: Contrasting
climate‐driven flowering
phenology and spread of
alien vs. native plants in
Britain
16
Example: Reclamation of new road sides – Suppression of invasive plants?
Seed mixtures to suppress invasive alien plants
Solidago gigantea
17
Background: Niche occupation, resources and competition with invasive plants
Scientific framework for grassland restoration and suppression of IAS
Kollmann et al. 2018, Restoration Ecology 18
School of Life Sciences Weihenstephan
Ecosystem scale
Community scale
Population scale
Legal and socio-
economic framework
Vacratot, 21 August 2018
Plant diversity and invasion resistance
19
The biotic resistance hypothesis predicts that an increase in the number of resident species enhances the use of resources and therefore reduces the establishment probability of invaders (D’Antonio & Chambers 2006)
Richardson 2011, Fifty years of invasion ecology: the legacy of Charles Elton
Charles Elton (1900–1991)
Plant diversity and invasion resistance
20
Diverse plant assemblages are more resistant to invasions due to a more exhaustive use of available resources (Elton 1958)
Diversity described as richness of either species numbers or functional groups (Levine & D'Antonio 1999; Pokorny et al. 2005)
Richardson 2011, Fifty years of invasion ecology: the legacy of Charles Elton
Charles Elton (1900–1991)
Resource competition: a mechanism of invasion success
Funk & Vitousek 2007, Nature; Gonzáles-Moreno et al. 2014, Diversity and Distributions 21
“Because no species can maximize growth, reproduction and competitive ability across all environments, the success of invasive species is habitat- or context-dependent.”
22
Case study 1: Invasive species and plant functional diversity moderate soil fertility in experimental grasslands
Funk et al. 2008, Trends in Ecology and Evolution 23
Theoretical background: Diversity-invasibility hypothesis
Effects of functional diversity on grassland invasion?
Investigates if functionally diverse communities can reduce IAS impacts on native biomass, soil and soil water nutrients.
Prediction: Higher functional diversity enhances biotic resistance of restored grasslands
24
• Four levels of functional groups (0, 1, 2, 3)
• Two levels of Solidago gigantea (+, -)
• Five blocks and eight treatment combinations (40 trays à 0.12 m2)
• 16 hours light period per day
• 21°C average temperature
• Five months
Invasive species effects on native plant biomass?
Direct and indirect effects on nutrients in soil and soil water?
Greenhouse experiment: design
Teixeira et al. 2018, submitted
Teixeira et al. 2018, submitted 25
Results: Effects on native plant emergence and biomass
Teixeira et al. 2018, submitted 26
Discussion: Effects on native plant emergence and biomass
Functional diversity does not affect native plants emergence but biomass production (in invaded communities).
Invaded communities have greater total biomass but less native plant biomass than uninvaded ones.
S. gigantea reduced emergence and biomass of native plants.
27Teixeira et al. 2018, submitted
Results: Effects on soil macronutrients
Solidago giganteaNo Solidago gigantea
28Teixeira et al. 2018, submitted
Results: Effects on soil macronutrients
Solidago giganteaNo Solidago gigantea
Functional diversity directly controls only two nutrient types in the soil (i.e. phosphate and ammonium)
The presence of S. gigantea disrupts the effects of functional diversity on soil nutrients
It creates new effects on nutrients by changing soil pH conditions via biomass
29
Case study 2: Preventing plant invasions at early stages of revegetation – the role of limiting similarity, relatedness and highly competitive species
Reducing invasibility of native communities: Biotic resistance
30
The ability of the native community to thwart the
invasion success of arriving non-native species
Reduced niche opportunities for invasive alien plant species
31
Similar species have the same symbol Native species are represented as colored shapes, invasive species as white shapes
Theoretical background: Trait-based community assembly rules
Funk et al. 2008, Trends in Ecology and Evolution
Limiting similarity predicts that invasive species will be unlikely to establish, if there are native species with similar traits present in the resident community or if available niches are occupied.
32
• Four levels of functional group indentity (FG1, 2a, b, 3)
• Two levels of propagule pressure
• Tested with Solidago gigantea and Ambrosia artemisiifolia
• 80 trays 0.12 m2, eight weeks
Effects of native species functional trait similarity on invasive species performance?
Effects of native species phylogenetic similarity on invasive species performance?
Greenhouse experiment: design
Yannelli et al. 2017, Oecologia
Native species
51 plant species
present in mesic
grasslands of
Central Europe
Invasive species
Methods: Clustering of species in functional groups and phylogeny
33
Invasive alien plants
Yannelli et al. 2017, Oecologia
Traits
Longevity
Life form
Shoot morphology
Root morphology
Seed mass
Canopy height
SLA
Dry leaf mass
Observations: Suppression of the two invasive alien species
FG1 + Amb art (HP) Control (HP)FG1 + Sol gig (HP) Control (HP)
Solidago gigantea Ambrosia artemisiifolia
34Yannelli et al. 2017, Oecologia
Results: Suppression of the two invasive alien species
Yannelli et al. 2017, Oecologia 35
Native communities Phylogenetic distance
Solidago gigantea Solidago gigantea
Ambrosia artemisiifolia Ambrosia artemisiifolia
High (black) and low (white) IAS propagule pressure (mean ± SE)
Weighted mean distance of IAS to each native species (grey), and distance to the most abundant
native species (black)
Results: Suppression of the two invasive alien species
Yannelli et al. 2017, Oecologia 36
Native communities Phylogenetic distance
Solidago gigantea Solidago gigantea
Ambrosia artemisiifolia Ambrosia artemisiifolia
Species of the same functional group do suppress less strongly
Suppression decreases with increasing phylogenetic distance
37
Case study 3: Restoring grasslands in a changing world – effects of limiting similarity versus seed density
Laughlin et al. 2014, Ecology Letters 38
Theoretical background: limiting similarity
Applying trait-based models for plant community design
Laughlin et al. 2014, Ecology Letters
Plant communities and design
40
Ambrosia artemisiifolia
40
Solidago gigantea
41
Greenhouse experiment: design
Yannelli et al. 2017, Oecologia
• Two native communities (AA and SG type)
• Tested separately with Solidago gigantea and Ambrosia artemisiifolia
• Monoculture of each invasive species
• Trays 0.12 m2 area, eight weeks, total of 36 trays
Native species functional trait similarity effect on invasive species performance?
Native plants
32 grassland species present in vegetation of the Bavarian lowlands
Results: Effects on height of invasive alien plants
Yannelli et al. 2017, Oecologia 42
aa
b
0
2
4
6
8
Control AA SG
Treatment
Inva
siv
e s
pp
s h
eig
ht (c
m)
A. artemisiifolia
aa
b
0.0
0.5
1.0
1.5
2.0
Control AA SG
Treatment
S.gigantea
IAS plants were taller in communities designed to suppress S. gigantea (SG)
AA + Ambrosia artemisiifolia
SG + Ambrosia artemisiifolia
Solidago giganteaAmbrosia artemisiifolia
Results: Effects on plant community density
Yannelli et al. 2017, Oecologia 43
aa
b
0
2
4
6
Control AA SG
Treatment
Le
af a
rea
in
de
x
Density was higher in communities designed to suppress S. gigantea (SG).
Results: Suppressive effect of the SG mixture
Yannelli et al. 2017, Oecologia 44
Aboveground IAS biomass was lower in communities designed to suppress S. gigantea (SG).
Solidago giganteaAmbrosia artemisiifolia
45
Case study 4: Restoring grasslands in a changing world – effects of competitive hierarchy, propagule pressure and extreme weather events
Laughlin et al. 2014, Ecology Letters 46
Theoretical background: Competitive hierarchies
Grime 1998, Journal of Ecology; Byun et al. 2015, Oecologia 47
Dominance effects – biomass ratio hypothesis
Interactions between abiotic constraints, propagule pressureand biotic resistance
Theoretical framework: Dominance–biomass hypothesis
Teixeira et al., unpubl. results 48
Methods: Native study plant species
• Classified according to their dominance hierarchy in natural sites (Ellenbergindicator values)
• Important traits for dominance hierarchy: seed mass, SLA, dry leaf area and canopy height
49
• Two levels of relative abundance (A, B)
• Two levels of propagule size (1, 3 g m-²)
• Two levels of propagule number (1, 3 times)
• Two levels of invasion (+, -)
• Extreme weather events (biweekly flooding and heating during 72 hours; five months)
Three replicates and eight treatment combinations (trays 0.12 m2)
o Plant emergence and vegetation cover
o Native and invasive plant biomass
o Soil and soil water nutrients
o Soil respiration (microbial metabolism)
Methods: Factorial experimental design
Using four climate chambers at TUMmesa we simulated climate change scenarios:
Teixeira et al., unpubl. results 50
Higher emergence of native plants in communities with fewer A. elatius, due to a higher number of (smaller) seeds
Native plant emergence in the same communities negatively affected by S. gigantea
Results: Suppression of natives by high seed densities and IAS
Teixeira et al., unpubl. results 51
When manipulating propagule pressure of invasive plants, patterns are repeated, i.e. higher emergence with fewer A. elatius
No clear effects of invasive plant propagule pressure on emergence of native plants
Results: Suppression of natives by high seed densities and IAS
Teixeira et al., unpubl. results 52
Emergence of S. gigantea not affected by competitive hierarchies of native plants
Propagule size is the main factor controlling invasive plant emergence
Results: Suppression of IAS by high seed densities
53
Conclusions for ecological restoration
Highlights of the results
54
Invasive plants interfere with community biomass, thus impacting nutrient stocks and reducing native species.
Altered nutrient conditions create a positive feedback for further invasions.
Functional diversity does not consistently reduce the impact of invasive alien species
Species of the same functional group are not more suppressive, while there are phylogenetic effects.
Emergence of invasive alien species independent of competitive hierarchies of native plants.
High seed densities suppress native and invasive alien species.
Food for thoughts
55
Biotic resistance of a community can be strongly influenced by occurrence of highly competitive species.
The functional trait selection has to consider traits correlated to all important plant responses and development stages.
To be discussed whether we have the right traits available in current trait databases.
Phylogenetic relatedness can be a helpful proxy when traits are difficult to measure.
Perspectives for future research and applications: Don‘t give up!
Foley et al. 2011, Nature 56
Test new species (combinations) based on functional similarity andphylogenetic relatedness
Verify results in field experiments
Develop commercial seed mixtures
Device improved sowing and managing recommendations
Contributions of ecological restoration!
Acknowledgements
Questions ?
References 1
58
Bellard, C., Thuiller, W., Leroy, B., Genovesi, P., Bakkenes, M. & Courchamp, F. (2013) Will climate change promote future invasions? Global Change Biology, 19, 3740–3748.
Byun, C., de Blois, S. & Brisson J. (2015) Interactions between abiotic constraint, propagule pressure, and biotic resistance regulate plant invasion. Oecologia, 178, 285–296.
Cardinale, B.J., Duffy, J.E., Gonzalez, A., Hooper, D.U., Perrings, C., Venail, P., Narwani, A., Mace, G.M., Tilman, D., Wardle, D.A.,Kinzig, A.P., Daily, G.C., Loreau, M., Grace, J.B., Larigauderie, A., Srivastava, D.S. & Naeem, S. (2012) Biodiversity loss and its impact on humanity. Nature, 486, 59–67.
CBD (Secretariat of the Convention on Biological Diversity) (2010) Global Biodiversity Outlook 3. Montréal, Canada.
Conti, G. & Díaz, S. (2013) Plant functional diversity and carbon storage – an empirical test in semi-arid forest ecosystems. Journal of Ecology, 101, 18–28.
Darwin, C. (1985) The Origin of Species by Means of Natural Selection. Penguin, London.
Ehrenfeld, J.G. (2010) Ecosystem consequences of biological invasions. Annual Review of Ecology, Evolution, and Systematics, 41, 59–80.
Funk, J.L., Cleland, E.E., Suding, K.N. & Zavaleta, E.S. (2008) Restoration through reassembly: plant traits and invasion resistance. Trends in Ecology & Evolution 23: 695–703.
Gamfeldt, L., Hillebrand, H. & Jonsson, P.R. (2008) Multiple functions increase the importance of biodiversity for overall ecosystem functioning. Ecology, 89, 1223–1231.
Gamfeldt, L., Snäll, T., Bagchi, R., Jonsson, M., Gustafsson, L., Kjellander, P., RuizJaen, M.C., Fröberg, M., Stendahl, J., Philipson, C.D., Mikusiński, G., Andersson, E., Westerlund, B., Andrén, H., Moberg, F., Moen, J. & Bengtsson, J. (2013) Higher levels of multiple ecosystem services are found in forests with more tree species. Nature Communications, 4, 1340.
Grime, J.P. 1998. Benefits of plant diversity to ecosystems: immediate, filter and founder effects. Journal of Ecology, 86, 902–910.
Hector, A. et al. (1999) Plant diversity and productivity experiments in European grasslands. Science, 286, 1123.
Hector, A. & Hooper, R. (2002) Darwin and the First Ecological Experiment. Science, 295, 639–640.
References 2
59
Hulme, P.E. (2011) Contrasting impacts of climate‐driven flowering phenology on changes in alien and native plant species distributions. New Phytologist, 189, 272–281.
Laughlin, D.C. (2014) Applying trait-based models to achieve functional targets for theory-driven ecological restoration. Ecology Letters, 17, 771–784.
Levin, S. 1999. Fragile Dominion: Complexity and the Commons. Perseus Books, Reading.
Levine, J.M., Adler, P.B. & Yelenik, S.G. (2004) A meta-analysis of biotic resistance to exotic plant invasions. Ecology Letters, 7, 975–989.
Loreau, M. & Hector, A. (2001) Partitioning selection and complementarity in biodiversity experiments. Nature, 412, 72–76.
Richardson, D.M. (Ed.). (2011). Fifty years of invasion ecology: the legacy of Charles Elton. John Wiley & Sons.
Thuiller, W., Richardson, D.M. & Midgley, G.F. (2008) Will climate change promote alien plant invasions? In: Nentwig W. (eds) Biological Invasions, pp. 197-211. Springer, Berlin.
van der Plas, F. et al. (2016). Jack-of-all-trades effects drive biodiversity–ecosystem multifunctionality relationships in European forests. Nature Communications, 7, 11109.
Yachi, S. & Loreau, M. (1999) Biodiversity and ecosystem productivity in a fluctuating environment: the insurance hypothesis. Proceedings of the National Academy of Sciences of the United States of America, 96, 1463–1468.
Yannelli, F.A., Hughes, P. & Kollmann, J. (2017) Preventing plant invasions at early stages of revegetation: The role of limiting similarity in seed size and seed density. Ecological Engineering, 100, 286–290.
Yannelli, F.A., Koch, C., Jeschke, J.M. & Kollmann, J. 2017. Limiting similarity and Darwin’s naturalization hypothesis: understanding the drivers of biotic resistance against invasive plant species. Oecologia, 183, 775–784.
Yannelli, F.A., Karrer, G., Hall, R., Kollmann, J. & Heger, T. (2018) Seed density is more effective than multi-trait limiting similarity in controlling grassland resistance against plant invasions in mesocosms. Applied Vegetation Science. doi10.1111/avsc.12373
Zavaleta, E.S., Pasari, J.R., Hulvey, K.B. & Tilman, G.D. (2010). Sustaining multiple ecosystem functions in grassland communities requires higher biodiversity. Proceedings of the National Academy of Sciences of the United States of America, 107, 1443–1446.