Stem Surface Injuries of several species of Columnar Cacti of

Ecuador

Annarita MacriManhattan College

Scaling and Barking

• Scale injury forms when there is a buildup of epicuticular waxes.

• Bark injury occurs when epidermal cells proliferate and accumulate on the surfaces

(Gibson and Nobel 1986, Duriscoe and Graban 1992, Evans 2005, Evans et al. 1994a, 1994b, 1994c, 1995).

This slide shows the types of injuries that have been observed and evaluated for almost two decades for cacti. Scale injuries have been shown to occur prior to barking injuries. These injuries have been shown to precede premature death in some cactus populations.

This slide shows a Jasminoceresus thoursaii specimen along the coast of Santa Maria, Galapagos Islands.

Photosynthetic Active Radiation (PAR)

• PAR is light between 400 and 730 nm • Program developed by Gary Geller • Program that calculates total PAR on a vertical

surface through the entire year• Program needs latitude and direction on

vertical surface

S

N

W E

This slide provides the background for the PAR model of Dr. Gary Geller. The model measured the amounts of PAR on vertical surfaces of columnar cacti at various latitudes. Dr. Geller generated this model in the 1980s and we had a copy of the model. The model gives daily values but also had the ability to accumulate PAR over an annual cycle.

4.0

1.0

Central Mexico

32oN Arizona

20oN

1.0

2.00o

1.41.4

1.0

1.0Ecuador

32oS Argentina/Chile

4.0

1.0

This slide shows the ratios of PAR generated by the Geller model at a variety of latitudes. At 32 degrees N and S, the PAR ratio was about 4:1, equatorial surfaces versus polar surfaces. At 20 N, the equatorial to polar ratio was 2:1. At the Equator, model predicts that the ratio of PAR at equatorial:polar surfaces will be 1.4:1. Our research in Ecuador was aimed at understanding if the ratio of injuries on columnar cacti would be 1.4:1 on stems.

EquatorEastWest

South

North

This slide alludes to the hypothesis that equatorial surfaces (East and West) should have 1.4 times more injuries than polar surfaces (north and south).

Equator

Equator

Galapagos Islands

Armatocereus cartwrightianus (A.C.)

Species

Pilosocereus lanuginosus

Jasminocereus thousarii (J.T.) Praecereus euchlorus var. diffusus (P.E.)

Species Continued

VegetationThis slide alludes to the fact that only cacti that were not surrounded by other vegetation could be used for this study. This limited the numbers of cacti that could be used for the study.

Measuring Injury

North 50%

West 75% East 100%

South 40%

Why Grouping?

HEALTHY INTERMEDAITE SICK

70%5%

50%

20%

15% 95%

Injury Class (%)

0-14.9 15-40 40.1-55 55.1-75

>75

This slide shows the five groups that cacti were grouped into. The reason for the groupings can be found in several publications in the curriculum vitae of Lance S. Evans. The above shows three examples between two sides of a cactus.

Armatocereus cartwrightianus n=99

Injury Average AverageClass (%) W + E vs N + S

0-14.9 7.7 4.4

15-40 27 15

40.1-55 48 33

55.1-75 66 57

>75 92 66

North

West

South

East

This slide shows the data for one of the species of this study. In all cases, the values for W + E are greater than for N + S.

Pooled data analysis of four species of columnar cacti of Ecuador

Injury Equatorial Polar Equatorial/ Chi-squareClass n surfaces surfaces Polar(%) mean (standard mean (standard ratio X2 Probability

deviation) deviation) value value

0-14.9 188 7.3(3.4) 4.8(5.7) 1.52 201 <0.01

15-40 222 26.1(8.2) 18.7(9.8) 1.40 215 <0.01

40.1-55 64 49.1(4.1) 35.9(6.9) 1.37 93 <0.01

55.1-75 85 66.5(5.9) 53.4(8.3) 1.25 122 <0.01

> 75 65 87.2(6.5) 70.6(12.1) 1.24 104 <0.01

This slide shows the analysis of the data for all four species of this study. In all cases, the values for equatorial surfaces were statistically higher than values for polar values. Note the ratios of from 1.24 to 1.52. Note the chi-square values and the probability values of less than 0.01. These results support our hypothesis that equatorial injuries were about 1.4 times greater than on polar surfaces.

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0.5

1

1.5

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2.5

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4.5

0 0.5 1 1.5 2 2.5 3 3.5 4

Ratio of PAR (Equator vs Polar)

Rat

io o

f In

juri

es (

Eq

uat

or

vs P

ola

r)

y=0.91x + 0.07 R2 =0.91

This slide shows the relationship between the ratio of injuries and ratio of PAR. Note the slope of 0.91 with an r2 value of 0.91. The data from Ecuador were at a ratio of 1.4.

0

0.5

1

1.5

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2.5

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4.5

0 5 10 15 20 25 30 35

Rat

io o

f E

qu

ato

rial

to

Po

lar

Inju

ries

Latitude (degrees)

y=0.003x2 - 0.028x + 1.37

R2 = 0.88

This slides shows the relationship between the ratio of injuries and latitude on the Earth’s surface. Note the equation in which the data at the equator are at 0 degrees. Overall, the data support our hypothesis that cacti at the equator have about 1.4 times more injuries on equatorial surfaces than on polar surfaces.