Mesic and Xeric diversity in the Subalpine Elk Meadow

Robert McFadzeanVegetation Ecology Summer B Semester, July 2014University of Colorado, Boulder, COMountain Research Station

Introduction

• Subalpine meadows play a crucial role in species diversity, supporting many endangered species of plant and wildlife.

• Subalpine meadows are found where temperatures are too cold or snow covers the ground for too long for trees to grow.

Introduction

• Studies show that moisture gradients greatly affect the vegetation diversity. ‘Soil moisture is critically important for plant diversity patterns’ (Moeslund et al : 2014)

• Mesic soils which are not oversaturated tend to be richer in nutrients and support greater plant diversity. (Fund et. Al: 2014)

QuestionIs there a difference in plant diversity within Xeric and Mesic sites of Elk Meadow?

IntroductionH0: There is no difference in species diversity between Xeric and Mesic sites in Elk Meadow.

H1: There is a difference between Xeric and Mesic site diversity in Elk Meadow.

I expect to find greater diversity in the Mesic site.

Mesic Xeric

MethodsAnalyze plant diversity across Xeric (Dry) and Mesic (Wet) landscapes located within Elk Meadow.

Mesic

Xeric

The Elk Meadow (Google Earth 2014)

MethodsBoth Mesic and Xeric sites are located in the Elk Meadow in the sub alpine with 3% Slope 108 Degrees E at 2963 meters.

5 randomly selected 20 X 50 cm Daubenmire plots per site.

Each individual species abundance.

A soil sample and water content was taken at each site and rated on a 1-5 scale, dry being 1 and wet being 5.

The observations are not representative of the entire subalpine zone on the Coloradan Front Range due to pseudo replication.

The samples do however represent an accurate profile of the Elk Meadow.

MethodsI used the Jaccard’s Index to quantify the similarities in species diversity between the areas.

Student t-test was used to test differences in species diversity (Shannon-Wiener).

Mann-Whitney rank sum was used to test for the Species Richness and Evenness differences.

Results19 Species in total

Tim

othy

Gra

ss

Yarro

w M

ilfoi

l

Whi

te S

age

Pote

ntill

a ar

gent

ea

Puss

ytoe

s

Unkno

wn

Long

leaf

Ston

ecro

p

Pote

ntill

a ar

guta

Purp

le H

areb

ell

Rye G

rass

Wal

lflow

er

Poa

prat

ensis

Alpin

e St

rawbe

rry

Smoo

th B

rom

e

Hoary

Gol

den

Aster

Gentio

n

Golde

n Ban

ner

Frin

ged

Sage

Sedg

e0

10

20

30

40

50

60

70

80

90

Mesic vs Xeric Species Distribution at Elk Meadow

Mesic Species FrequencyXeric Species Frequency

Species

Frequency

Results

Average H(SW) Average Evenness Average Species0

1

2

3

4

5

6

7

8

9

10

Species Richness , Diversity and Evenness for Xeric vs Mesic Sites

XericMesic

Species Richness (Average Species), Diversity (H, Shannon Weiner) and Evenness

Average Values

P-Value (Mann-Whit-ney) for EvennessP = 0.30 NOT SIGNIFICANT

P-Value (Mann-Whit-ney) for Average Species P = 0.012 Significant

P-Value (T-Test) for Di-versity (SW) P=0.0013 Significant

ResultsJaccard’s Index: 0.42

Mesic Xeric42% Similar

Mesic Species42%

Unique Xeric Species

58%

Representation of Jaccard's Index

Discussion• Species Richness and the Shannon Wiener

Index are significantly higher in the Xeric areas of Elk Meadow.

• The Xeric site contained 11 Unique species of the total 19 species found at all sites.

• Evenness across the two sites were similar and not significantly different.

• Jaccard’s index shows a large difference in diversity.

• Observations indicate that productivity is higher in the Mesic areas given the visible biomass of species present.

Discussion

Mesic areas tended to have great abundance of species which were there.

‘Shifts in plant species composition toward more diverse communities and toward communities characteristic of more xeric environments are also expected, further lowering productivity without a change in mean soil moisture.’ (Knapp et al: 2002)

Further research looking at the biomass within the two sites including measuring species heights could shed light on the differences seen.

ConclusionsThe subalpine Elk Meadow is more diverse in species within Xeric areas than Mesic Areas.

Although Xeric areas are more diverse in Elk Meadow, the productivity of the Mesic areas may be greater.

Both Xeric and Mesic areas share similar Evenness.

Further research should include measuring the heights and basal area of species.

Questions

References1. Fund, W. (2014). Qilian Mountains subalpine meadows.

Retrieved from http://www.eoearth.org/view/article/155625

2. Knapp AK, Fay PA, Blair JM, Collins SL, Smith MD, Carlisle JD, Harper CW, Danner BT, Lett MS, McCarron JK. 2002. Rainfall variability, carbon cycling and plant species diversity in a mesic grassland. Science 298: 2202–2205.

3. Moeslund JE, Arge L, Bøcher PK, Dalgaard T, Ejrnæs R, Odgaard MV, Svenning J-C (2013) Topo-graphically controlled soil moisture drives plant diversity patterns within grasslands. Biodivers Con- serv. doi:10.1007/s10531-013-0442-3

4. Mueller-Dombois, D. Ellenberg, H. Aims and Methods of Vegetation Ecology. The Blackburn Press. Caldwell, New Jersey US. 2002. 62-63.