What determines disturbance‐productivity‐diversity relationships? The effect of scale, species and environment on richness patterns in an Australian woodland

Much of the observed variation in relationships between diversity and disturbance or productivity may be attributed to scale, species characteristics, or environment. We used exclusion fences to create gradients of grazing (by native and introduced herbivores), cover, and standing crop in temperate Eucalypt woodlands. We investigated patterns of native, exotic, and total plant species richness at two scales (1 m 2 and 625 no Richness patterns were similar at both scales, though species richness at 1m 2 was more strongly affected by our grazing treatments. Season and rainfall explained more variation in richness than did surrogate measures of productivity or disturbance by herbivores. The richness-herbivory relationship depended strongly on rainfall, season, and species origin, and altering these factors produced the entire range of observed diversity-disturbance relationships. Richness-biomass and richness-cover relationships were consistently hump-shaped, and related to species origin with native richness negatively related and exotic richness positively related. The ability of weedy annuals to pre-empt space after death may have contributed to the observed unimodal responses.

[1]  James B. Grace,et al.  Perspectives on Plant Competition , 1991 .

[2]  J. P. Grime,et al.  Interacting effects of herbivory and fertility on a synthesized plant community , 1999 .

[3]  A. J. Underwood,et al.  Experiments in Ecology: Their Logical Design and Interpretation Using Analysis of Variance , 1997 .

[4]  J. Oksanen.  Is the humped relationship between species richness and biomass an artefact due to plot size , 1996 .

[5]  R. Littell.  SAS System for Mixed Models , 1996 .

[6]  L. Aarssen.  High productivity in grassland ecosystems : effected by species diversity or productive species ? , 1997 .

[7]  O. Sala,et al.  A Generalized Model of the Effects of Grazing by Large Herbivores on Grassland Community Structure , 1988, The American Naturalist.

[8]  Jonathan M. Chase,et al.  Spatial scale dictates the productivity–biodiversity relationship , 2002, Nature.

[9]  Michael A. Huston,et al.  Local processes and regional patterns : appropriate scales for understanding variation in the diversity of plants and animals , 1999 .

[10]  D. Currie,et al.  THE DIVERSITY–DISTURBANCE RELATIONSHIP: IS IT GENERALLY STRONG AND PEAKED? , 2001 .

[11]  M. Palmer,et al.  Linking species diversity to the functioning of ecosystems: on the importance of environmental context , 2000 .

[12]  P. Chesson.  Mechanisms of Maintenance of Species Diversity , 2000 .

[13]  P. White,et al.  The Ecology of Natural Disturbance and Patch Dynamics , 1986 .

[14]  J. Connell.  Diversity in tropical rain forests and coral reefs. , 1978, Science.

[15]  P. Adler,et al.  Compensation: an alternative method for analyzing diversity‐productivity experiments , 2002 .

[16]  M. Zobel.  Plant species coexistence - the role of historical, evolutionary and ecological factors , 1992 .

[17]  J. Eisenberg,et al.  Serengeti: Dynamics of an Ecosystem , 1980 .

[18]  S. Prober,et al.  Conservation of the grassy white box woodlands: relative contributions of size and disturbance to floristic composition and diversity of remnants. , 1995 .

[19]  R. Parmenter,et al.  Vegetation change following removal of keystone herbivores from desert grasslands in New Mexico , 2001 .

[20]  H. Olff,et al.  Effects of herbivores on grassland plant diversity. , 1998, Trends in ecology & evolution.

[21]  D. Wardle.  Is "Sampling Effect" a Problem for Experiments Investigating Biodiversity-Ecosystem Function Relationships? , 1999 .

[22]  E. Weiher.  The combined effects of scale and productivity on species richness , 1999 .

[23]  S. Harrison.  Native and alien species diversity at the local and regional scales in a grazed California grassland , 1999, Oecologia.

[24]  R. J. Olson,et al.  Estimating net primary productivity from grassland biomass dynamics measurements , 2002 .

[25]  P. Petraitis,et al.  The Maintenance of Species Diversity by Disturbance , 1989, The Quarterly Review of Biology.

[26]  J. Connell,et al.  Mechanisms of Succession in Natural Communities and Their Role in Community Stability and Organization , 1977, The American Naturalist.

[27]  H. Safford,et al.  GRAZING AND SUBSTRATE INTERACT TO AFFECT NATIVE VS. EXOTIC DIVERSITY IN ROADSIDE GRASSLANDS , 2001 .

[28]  I. Lunt.  Species‐area curves and growth‐form spectra for some herb‐rich woodlands in western Victoria, Australia , 1990 .

[29]  P. Hulme.  HERBIVORES AND THE PERFORMANCE OF GRASSLAND PLANTS : A COMPARISON OF ARTHROPOD, MOLLUSC AND RODENT HERBIVORY , 1996 .

[30]  T. Stohlgren,et al.  How grazing and soil quality affect native and exotic plant diversity in Rocky Mountain grasslands , 1999 .

[31]  Han Olff,et al.  Herbivores Between Plants and Predators , 1999 .

[32]  J. Bergelson.  Life After Death: Site Pre‐Emption by the Remains of Poa Annua , 1990 .

[33]  Katherine L. Gross,et al.  WHAT IS THE OBSERVED RELATIONSHIP BETWEEN SPECIES RICHNESS AND PRODUCTIVITY , 2001 .

[34]  W. Sousa.  The Role of Disturbance in Natural Communities , 1984 .

[35]  L. Oksanen.  Predation, herbivory, and plant strategies along gradients of primary productivity. , 1990 .

[36]  M. Huston.  A General Hypothesis of Species Diversity , 1979, The American Naturalist.

[37]  J. P. Grime.  Control of species density in herbaceous vegetation , 1973 .

[38]  J. Bakker,et al.  Effects of resource competition and herbivory on plant performance along a natural productivity gradient , 2000 .

[39]  H. Olff,et al.  Herbivore diversity and plant dynamics: compensatory and additive effects , 1999 .

[40]  Anke Jentsch,et al.  The Search for Generality in Studies of Disturbance and Ecosystem Dynamics , 2001 .

[41]  D. Milchunas,et al.  Quantitative Effects of Grazing on Vegetation and Soils Over a Global Range of Environments , 1993 .

[42]  S. McNaughton,et al.  Serengeti Grassland Ecology: The Role of Composite Environmental Factors and Contingency in Community Organization , 1983 .

[43]  D. Tilman.  THE ECOLOGICAL CONSEQUENCES OF CHANGES IN BIODIVERSITY: A SEARCH FOR GENERAL PRINCIPLES101 , 1999 .

[44]  Michel Loreau,et al.  Biodiversity and ecosystem functioning: recent theoretical advances , 2000 .

[45]  Jeff Short.  The functional response of kangaroos, sheep and rabbits in an arid grazing system , 1985 .

[46]  S. Lavorel,et al.  Predicting Richness of Native, Rare, and Exotic Plants in Response to Habitat and Disturbance Variables across a Variegated Landscape , 1994 .

[47]  Marcel Rejmánek,et al.  Species pools and the "hump-back" model of plant species diversity : an empirical analysis at a relevant spatial scale , 2001 .

[48]  M. Loreau,et al.  Plant species richness and community productivity: why the mechanism that promotes coexistence matters , 2002 .

[49]  A. Mazumder,et al.  REVERSAL OF GRAZING IMPACT ON PLANT SPECIES RICHNESS IN NUTRIENT‐POOR VS. NUTRIENT‐RICH ECOSYSTEMS , 1998 .

[50]  M. Willig,et al.  The Relationship Between Productivity and Species Richness , 1999 .

[51]  Nancy Huntly,et al.  Herbivores and the dynamics of communities and ecosystems , 1991 .

[52]  G. Saunders,et al.  INITIAL EFFECTS OF RABBIT HAEMORRHAGIC DISEASE ON FREE-LIVING RABBIT (ORYCTOLAGUS CUNICULUS) POPULATIONS IN CENTRAL-WESTERN NEW SOUTH WALES , 1999 .