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Vegetation Patterns of the Tallgrass Prairie: A Proposal. Daniel McGlinn. Map courtesy of PG Earls. McGlinn 2005. Outline. Introduction The Species pool hypothesis and turnover The Tallgrass Prairie Preserve Management methods and goals Species-area and species-time theory

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Vegetation Patterns of the Tallgrass Prairie: A Proposal

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Vegetation Patterns of the Tallgrass Prairie: A Proposal

Daniel McGlinn

Map courtesy of

PG Earls


McGlinn 2005

Outline

  • Introduction

    • The Species pool hypothesis and turnover

  • The Tallgrass Prairie Preserve

    • Management methods and goals

  • Species-area and species-time theory

  • Preliminary analyses: diversity through space and time

  • Future Questions


McGlinn 2005

Speciation

large-scale migration

small-scale migration

dispersal

Filtering

Actual species pool

Local species pool

Regional species pool

Species pool hypothesis

Abiotic factors and

Biotic interactions

Redrawn from Zobel 1997


McGlinn 2005

Development of Species-pool hypothesis

  • Importance of regional species pool

    • Zobel 1997

  • Evolutionary or historic soil conditions determine local species richness (SR)

    • Pärtel 2002 and Ewald 2003

  • Exotics may provide key insight

    • Palmer 2003


McGlinn 2005

Field of Dreams hypothesis

  • Special case of Species-pool hypothesis

    • Palmer et al. 1997

  • If you build it (disturbance regime), they will come…

    • Evolutionary pattern of burning and grazing

  • Predicts an increase in natives and a decrease in abundance and richness of exotics


McGlinn 2005

Speciation

large-scale migration

small-scale migration

dispersal

Filtering

Actual species pool

Local species pool

Regional species pool

Species pool hypothesis

Abiotic factors and

Biotic interactions

Redrawn from Zobel 1997


McGlinn 2005

Turnover

  • Species level

    • Carousel model: van der Maarel & Sykes 1997

    • Mobility indices: Palmer and Rusch 2001

  • Community level

    • Species-area curve: Watson 1859

    • Species-time curve: Preston 1960


McGlinn 2005

Community level turnover

  • Species-area and species-time relationships

    • Preston’s (1960) ergodicconjecture – Rosenzweig 1995,1998

    • Tested for time-space interaction – Adler and Lauenroth (2003)

    • Sampling and ecological effects – White (2004)


McGlinn 2005

The Tallgrass PrairiePreserve

  • 15,000-hectare natural area

  • Owned by TNC since 1989

  • Bison introduced 1993

  • Randomized burning regime began 1993

  • Ecological goal:

    • To create a heterogeneous landscape that contains the full compliment of native species


McGlinn 2005

Current data

  • UTM grid 1997-2000

  • 20 quadrats resampled 1998-2004

    • Plots chosen randomly with criteria that it not have any woody cover, standing water, or >20% rock cover


McGlinn 2005

10 m

Map courtesy of PG Earls


McGlinn 2005

Randomized Burning

  • Simulate the presettlement fire frequency and seasonality

  • Burn units selected randomly from areas with a minimum fuel load

  • Creates aspatially and temporally dynamic landscape


McGlinn 2005

Species-area and Species-time

  • Structure of the equation

    • c, z, and w values

  • Empirical results

    • linearity and nonlinearity

  • Mechanisms drive patterns

    • Statistical, ecological, evolutionary


McGlinn 2005

Structure of SAR

  • c and z values;

  • c is often only interpreted as a mere intercept

  • Non-linear form of SAR shows that c actually helps to determine the slope


McGlinn 2005

Structure of STR

  • Same as SAR

  • Rate of species accumulation is w


McGlinn 2005

Empirical curves from the TGPP

Fig from Palmer et al. (2003)

z = 0.30

Log # Species

Log Area


McGlinn 2005

Empirical patterns

Rosenzweig 1995


McGlinn 2005

TGPP quadrat scale

Preston 1960


McGlinn 2005

Current findings

  • Species richness has significantly increased in the twenty 10x10 plots from 1998 to 2004

  • SAR is slightly convex in log-log space

  • STR more linear in log-log space

  • The rate of species-accumulation decreases at the same rate for increasing area and increasing time


McGlinn 2005


McGlinn 2005


McGlinn 2005

Mean r2 = 0.9816


McGlinn 2005

Mean r2 = 0.9982


McGlinn 2005

z

w

log A

log T

Decreasing rate of species accumulation

Slopes of species-area curves

Slopes of species-time curves


McGlinn 2005


McGlinn 2005

Remaining questions

  • Continue to resample plots

    • When does ecological change begin to take place

    • How does fire and grazing effect the shape of this relationship

  • At what scale do spatial and temporal accumulation of species seem equivalent?

    • Is this the same as for Konza (47 m2)?

  • Is the way that organisms move from one location to another analogous to their ‘movement’ through time?


McGlinn 2005

Questions


McGlinn 2005

Other explanations abound…

  • Exotics maintain or increase

    • A more heterogeneous landscape structurally provides more niches

    • Exotics are inherently generalists and can adapt rapidly to new environments – highly plastic phenotypes


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