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United States Department of Agriculture (USDA) 2000

CLIMATE CHANGE, GRASS INVASIONS, AND WOODY PLANT DYNAMICS IN SEMI-ARID SAVANNAS

Climate Change, Semi-arid Savannas

United States Department of Agriculture (USDA) Research, Education & Economics Information System (REEIS)

Titre : CLIMATE CHANGE, GRASS INVASIONS, AND WOODY PLANT DYNAMICS IN SEMI-ARID SAVANNAS

Identification : TENR-2000-00752

Pays : Etats Unis

Durée : Sep 1, 2000 à Feb 28, 2005

Domaine : Management of Range Resources ; Rangelands and grasslands, general

Partenaire : UNIVERSITY OF TENNESSEE 2621 MORGAN CIR KNOXVILLE,TN 37996-4540

Objectifs
Investigate rates and patterns of recruitment of velvet mesquite (Prosopis velutina) seedlings on native rangeland in southern Arizona. Determine whether rates of mesquite recruitment are negatively affected by an invasive grass common to the region, Lehmann lovegrass (Eragrostis lehmanniana). Determine role of summer- versus winter-derived precipitation in affecting rates of mesquite recruitment. Determine how different geomorphic surfaces (Holocane-age, low-clay soils and Pleistocene-age, high-clay soils) may affect mesquite recruitment. Determine relative importance of invasive grasses, precipitation regimes, and geomorphic surfaces on rates and patterns of mesquite recruitment, growth, and physiological response

Descriptif
We will establish a large-scale manipulative experiment to determine how rates of recruitment of woody plants within grasslands may be affected by invasive grasses, seasonal precipitation regimes, and underlying soil characteristics. Research will be conducted on native rangeland in southern Arizona. We will experimentally alter native and non-native grass cover and seasonal precipitation at field sites with soils that have different degrees of clay horizon development. Plots will be established on Holocene-age, low-clay soils and Pleistocene-age, high-clay soils. Existing vegetation will be removed, and will be replaced by planted stands of a native grass (sideoats grama) or a non-native, invasive grass (Lehmann lovegrass). Plots will be decoupled from ambient precipitation and soil moisture by erecting movable precipitation shelters over them and trenching and lining their sides. The demographic and physiologic responses of mesquite introduced as seeds into experimental plots will be used to gauge the potential recruitment of this species under different environmental conditions and to investigate linkages between seedling water stress and demographic response.

Présentation : USDA

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