Tag: Plants

Soil Organic Matter and Nutrient Availability Responses to Reduced Plant Inputs in Shortgrass Steppe

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Author: Kelly, Robin H.; Burke, Ingrid C.; Lauenroth, William K. Description: We examined soil organic matter (SOM) dynamics in a shortgrass steppe ecosystem along spatial gradients in plant inputs and temporal gradients in disturbance age because a better understanding of decay characteristics of SOM pools may improve our ability to predict ecosystem responses to perturbation. We assessed measurable pools of SOM that are thought to correspond to active, intermediate, and passive SOM based upon turnover characteristics in three separate experiments. In a first, we evaluated SOM pools along a spatial…

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Landscape Patterns in Soil-Plant Water Relations and Primary Production in Tallgrass Prairie

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Author: Knapp, A. K.; Fahnestock, J. T.; Hamburg, S. P.; Statland, L. B.; Seastedt, T. R.; Schimel, D. S. Description: Landscape variation in soil water relations, leaf xylem pressure potential (°) and leaf-level net photosynthesis (A) in Andropogon gerardii, and net primary production (NPP) were evaluated during the 1989 and 1990 growing seasons in a northeast Kansas (USA) tallgrass prairie. Landscape patterns were assessed along transects that spanned upland and lowland topographic positions in an annually burned and a long-term unburned watershed. Landscape variability in volumetric soil water content (°)…

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Oak Tree Effects on Soil and Herbaceous Vegetation in Savannas and Pastures in Wisconsin

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Author: Ko, Leonora J.; Reich, Peter B. Description: To study tree/nontree interactions, soil characteristics, aboveground biomass and plant composition were compared in areas under and adjacent to canopies of open grown bur oaks (Quercus macrocarpa) and northern pin oak x black oak hybrids (Q. ellipsoidalis x velutina) in two savannas and two pastures in S-central Wisconsin. One savanna and one pasture were paired on loam soils, the other sites were on sandy soils. In general, soil moisture was higher below tree canopies than outside canopies during a drying trend and…

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Fire and Litter Effects in Undisturbed Bluestem Prairie in Kansas

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Author: Hulbert, Lloyd C. Description: Two-by-two-meter plots of undisturbed, nearly pure Andropogon gerardi prairie were subjected to four treatments: burning, clipping and removal of the litter, burning the clipped litter and returning the ash, and the control (natural litter). Treatments were started in early April before growth began. Differences in results among the denuded plots were small and nonsignificant, but highly significant differences were found between denuded and control plots. Tiller number was increased 1.5 to 2.7 times by removal of litter. Growth began earlier in denuded than control plots….

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Plant Response to Herbivory and Belowground Nitrogen Cycling

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Author: Holland, Elizabeth A.; Detling, James K. Description: Plant responses to herbivory and links to belowground nitrogen cycling were investigated at Wind Cave National Park, South Dakota. Laboratory estimates of net nitrogen mineralization were highest in soils from the more altered areas of prairie dog colonies (Cynomys ludovicianus) and lowest in the adjacent, lightly grazed, uncolonized grassland. The ratio of CO2: net nitrogen mineralized, as index of immobilization, was highest in the uncolonized grassland and lowest in the altered core areas. Soil moisture was an important modifier of in situ…

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Managing Species Diversity in Tallgrass Prairie: Assumptions and Implications

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Author: Howe, Henry F. Description: Conservation and restoration ecology efforts may conserve or restore a particular image of a community, a variety of plausible images, or maximum biological diversity. The choice is a policy decision that should reflect relevant history and sound science. Here I argue that common methods of conserving and restoring tallgrass prairie have a weak scientific rationale, are not consistent with plausible history, and threaten prairie biodiversity. Dormant-season burns and grazer exclusion are human interventions that may promote artificially consistent dominance of large grasses utilizing the C4…

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Succession and Fire Season in Experimental Prairie Plantings

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Author: Howe, Henry F. Description: Fire season influenced the cover of species and flowering guilds of plants in replicated grass and forb plantings of tallgrass prairie species in Wisconsin. Over two burn cycles at 3-yr intervals, cover increased in the rhizomatous perennials Andropogon gerardii, Aster simplex and Solidago altissima in plots burned in spring, or summer, or left unburned, but cover showed dramatic positive or negative responses to spring or summer burns in Agropyron repens, Erigeron annuus, Panicum virgatum, Phalaris arundinacea, and Rudbeckia hirta. Aggregate response of flowering guilds was…

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Disturbance, Diversity, and Invasion: Implications for Conservation

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Author: Hobbs, Richard J.; Huenneke, Laura F. Description: Disturbance is an important component of many ecosystems, and variations in disturbance regime can affect ecosystem and community structure and functioning. The “intermediate disturbance hypothesis” suggests that species diversity should be highest at moderate levels of disturbance. However, disturbance is also known to increase the invasibility of communities. Disturbance therefore poses an important problem for conservation management. Here, we review the effects of disturbances such as fire, grazing, soil disturbance and nutrient addition on plant species diversity and invasion with particular emphasis…

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Evolutionary Ecology across Three Trophic Levels: Goldenrods, Gallmakers, and Natural Enemies

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Author: Abrahamson, Warren G.; Weis, Arthur E. Description: In a work that will interest researchers in ecology, genetics, botany, entomology, and parasitology, Warren Abrahamson and Arthur Weis present the results of more than twenty-five years of studying plant-insect interactions. Their study centers on the ecology and evolution of interactions among a host plant, the parasitic insect that attacks it, and the suite of insects and birds that are the natural enemies of the parasite. Because this system provides a model that can be subjected to experimental manipulations, it has allowed…

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The Plant Microbiota: Systems-Level Insights and Perspectives

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Author: Muller, Daniel B.; Vogel, Christine; Bai, Yang; Vorholt, Julia A. Description: Plants do not grow as axenic organisms in nature, but host a diverse community of microorganisms, termed the plant microbiota. There is an increasing awareness that the plant microbiota plays a role in plant growth and can provide protection from invading pathogens. Apart from intense research on crop plants, Arabidopsis is emerging as a valuable model system to investigate the drivers shaping stable bacterial communities on leaves and roots and as a tool to decipher the intricate relationship…

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