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Influence Of Resource Pulses And Perennial Neighbors On The Establishment Of An Invasive Annual Grass In The Mojave Desert, Rebecca E. Drenovsky, J. J. James, M. A. Caird, R. L. Sheley
Influence Of Resource Pulses And Perennial Neighbors On The Establishment Of An Invasive Annual Grass In The Mojave Desert, Rebecca E. Drenovsky, J. J. James, M. A. Caird, R. L. Sheley
Biology
Invasion by exotic annual grasses is one of the most significant threats to arid ecosystems in the western USA. Current theories of invasibility predict plant communities become more susceptible to invasion whenever there is an increase in the amount of unused resources. The objective of this field study was to examine how resource pulses and temporal variation in resource demand by the native shrub vegetation influences establishment of the invasive annual grass Schismus arabicus. Water and nitrogen were applied as pulses in early spring, mid-spring, or continuously throughout the growing season to plots containing either Atriplex confertifolia or Atriplex …
The Evolution Of Organismal Complexity In Angiosperms As Measured By The Information Content Of Taxonomic Descriptions, J. Gordon Burleigh, Justen B. Whittall, Michael J. Sanderson
The Evolution Of Organismal Complexity In Angiosperms As Measured By The Information Content Of Taxonomic Descriptions, J. Gordon Burleigh, Justen B. Whittall, Michael J. Sanderson
Biology
We describe an information theoretic method for measuring relative organismal complexity. The complexity measure is based on the amount of information contained in formal taxonomic descriptions of organisms. We examine the utility of this measure for quantifying the complexity of plant families. The descriptions are subjective by nature, but we find a significant correlation in the complexity values of plant families from two independently authored sets of formal taxonomic descriptions. An analysis of the evolution of complexity across angiosperms found evidence of a pattern of increasing complexity. Our measure of complexity provides an operational definition of complexity that may be …
Soil Microbial Community Composition As Affected By Restoration Practices In California Grassland, Rebecca E. Drenovsky, Martin Pothoff, Kerri L. Steenwerth, Louise E. Jackson, Rainer G. Joergensen, Kate M. Scow
Soil Microbial Community Composition As Affected By Restoration Practices In California Grassland, Rebecca E. Drenovsky, Martin Pothoff, Kerri L. Steenwerth, Louise E. Jackson, Rainer G. Joergensen, Kate M. Scow
Biology
Agricultural practices have strong impacts on soil microbes including both the indices related to biomass and activity as well as those related to community composition. In a grassland restoration project in California, where native perennial bunchgrasses were introduced into non-native annual grassland after a period of intensive tillage, weeding, and herbicide use to reduce the annual seed bank, microbial community composition was investigated. Three treatments were compared: annual grassland, bare soil fallow, and restored perennial grassland. Soil profiles down to 80cm in depth were investigated in four separate layers (0–15, 15–30, 30–60, and 60–80cm) using both phospholipid ester-linked fatty acid …
Low Leaf N And P Resorption Contributes To Nutrient Limitation In Two Desert Shrubs, Rebecca E. Drenovsky, J. H. Richards
Low Leaf N And P Resorption Contributes To Nutrient Limitation In Two Desert Shrubs, Rebecca E. Drenovsky, J. H. Richards
Biology
Both water and nutrients are limiting in arid environments, and desert plants have adapted to these limitations through numerous developmental and physiological mechanisms. In the Mono Basin, California, USA, co-dominant Sarcobatus vermiculatus and Chrysothamnus nauseosus ssp. consimilis are differentially N and P limited. We hypothesized that low leaf N resorption contributes to N-limitation in Sarcobatus and that low leaf P resorption contributes to P-limitation in Chrysothamnus. As predicted, Sarcobatus resorbed proportionally 1.7-fold less N than Chrysothamnus, but reduced leaf P in senescent leaves to lower levels than Chrysothamnus (8.0–10.8-fold lower based on leaf area or mass, respectively), consistent with N, …