Location: National Soil Erosion Research Lab
Title: The Influence of Encroaching Woodland on Grassland Enzymatic Activities Author
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 5, 2010
Publication Date: October 31, 2010
Citation: Stott, D.E. 2010. The Influence of Encroaching Woodland on Grassland Enzymatic Activities [abstract]. American Society of Agronomy-Crop Science Society of America-Soil Science Society of America Annual Meeting, October 31-November 4, 2010, Long Beach, CA. CD ROM. Technical Abstract: Grass-dominated ecosystems around the world are experiencing woody plant invasion due to human land uses. Vast regions in southern Texas have been transformed from open grasslands to subtropical thorn woodlands during the past 150 yrs. The assumption is that the soil microbial activity in the remaining grasslands remains unaffected by the nearby woody clusters. An experiment was designed to test this hypothesis by sampling grasslands measuring potential soil enzymatic activities. Samples were taken from Texas Agricultural Experiment Station La Copita Research Area (mean annual precipitation = 715 mm; mean annual temperature = 22.4 °C). Topography consists of nearly level uplands which grade (1-3% slopes) into lower-lying drainage woodlands. This formerly grassland plain is subject to invading woodlands. The woody areas form “clusters” surrounding a single mesquite tree, which over time merge into patches of woodlands. The mesquite is the first species to invade, which then provides support for other woody species in its understory. The age of the clusters were determined through measuring basal diameters of the oldest mesquite tree. Soil cores were taken in the grasslands 15 feet away from each cluster canopy edge. Five enzymes activities were measured: ß-1,4 glucosidase (BG), N-acetyl-ß-D-glucosaminidase (NAG), acid phosphatase (APH), arylamidase (AM), fluorescein diacetate hydrolysis (FDAH) , phenol oxidase (PO). Results will be discussed.