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Determining soil-tree-grass relationships in a California oak savanna using eco-geophysics

David A. Robinson, Inma Lebron and Jose Ignacio Querejeta
Determining soil-tree-grass relationships in a California oak savanna using eco-geophysics (in Coupling soil science and hydrology with ecology, Michael H. Young (prefacer), David A. Robinson (prefacer) and Ronald J. Ryel (prefacer))
Vadose Zone Journal (August 2010) 9 (3): 528-536


Savanna ecosystems have long fascinated ecologists due to the codominance of trees and grasses. This codominance is often explained by the vertical juxtaposition of rooting depths leading to niche separation for water uptake. The tree-grass spatial patterns observed are often investigated within the competition, disturbance, and resource heterogeneity framework. Ecohydrologic studies are developing models to describe patterns based on this framework and the complex interplay between climate, soil moisture, and resource heterogeneity. A common impediment to unraveling the relative importance of each of these factors is a lack of detailed spatial and temporal data describing resource heterogeneity. In this research, we investigated the use of electromagnetic-induction (EMI) imaging as a way of determining soil spatial resource heterogeneity. The aim was to determine if EMI signal response, reflecting soil texture and moisture, can provide a rapid method for identifying soil spatial resource heterogeneity, thus providing a novel method to help differentiate between the importance of competition, disturbance, and resource heterogeneity in controlling tree-grass pattern development. We found a significant difference (t=10.18, P=1.57X10 (super -21) ) between signal response under grass and trees. Higher bulk soil electrical conductivity (ECa) values occurred under grass ( approximately 32 mS m (super -1) ), indicating more clay, while lower ECa values ( approximately 21 mS m (super -1) ) occurred under trees where clay content was less. Significant ECa differences were also observed between the oak (Quercus spp.) and buckeye [Aesculus californica (Spach) Nutt.] tree communities, but not between the evergreen and deciduous oak communities. Soil ECa provides a rapid measurement method to identify soil resource heterogeneity in savanna tree-grass systems and could provide a vital tool for woodland restoration planning.

ISSN: 1539-1663
Serial Title: Vadose Zone Journal
Serial Volume: 9
Serial Issue: 3
Title: Determining soil-tree-grass relationships in a California oak savanna using eco-geophysics
Title: Coupling soil science and hydrology with ecology
Author(s): Robinson, David A.Lebron, InmaQuerejeta, Jose Ignacio
Author(s): Young, Michael H.prefacer
Author(s): Robinson, David A.prefacer
Author(s): Ryel, Ronald J.prefacer
Affiliation: Environment Centre Wales, Centre for Ecology and Hydrology, Bangor, United Kingdom
Affiliation: Desert Research Institute, Division of Hydrologic Sciences, Las Vegas, NV, United States
Pages: 528-536
Published: 201008
Text Language: English
Publisher: Soil Science Society of America, Madison, WI, United States
References: 63
Accession Number: 2010-088897
Categories: Environmental geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
Source Medium: WWW
N37°25'60" - N37°25'60", W122°10'00" - W122°10'00"
Secondary Affiliation: Environment Centre Wales, GBR, United KingdomUtah State University, USA, United StatesCSIC, Centro de Edafologia y Biologia Aplicada del Segura, ESP, Spain
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Soil Science Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201047
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