On the use of three performance measures for fitting species response curves

Autor: Antonio Torres‐Martínez, Dolores Ferrer-Castán, Miguel A. Esteve‐Selma, José F. Calvo, Luis Ramírez-Díaz
Rok vydání: 1995
Předmět:
Zdroj: Journal of Vegetation Science. 6:57-62
ISSN: 1654-1103
1100-9233
DOI: 10.2307/3236256
Popis: response models: density (stem counts per unit area),cover, biomass - or some alternative non-destructivemeasures such as volume -, etc. However, most of theavailable information for examining the species responseshape is based on qualitative data (presence/absence),and little attention has been paid to ascertaining whetherthis shape is independent (or not) of the response meas-ures considered.This paper examines quantitative response surfacesobtained from several species performance measures,i.e. density, cover and volume, of Periploca angustifolia(Asclepiadaceae ), in southeastern Spain. The main aimis to compare the shape of the responses, which weredetermined with the help of generalized linear models(GLM; McCullagh & Nelder 1989). This method wassuggested by Austin et al. (1984) as an approach thatallows an explicit rigorous analysis to be made of theshape of species response to a number of environmentalfactors considered simultaneously (cf. Austin et al. 1990).The response variables were related to complex gra-dients (sensu Whittaker 1956, 1967) of aspect, slopeangle and elevation as their use assumes that manysingle factors that change together in space - incomingsolar radiation, temperature, humidity, wind velocity -may be important for plant distribution. Therefore, meas-ures of aspect, slope angle and altitude are used here ascrude indices of relative position along complex envi-ronmental gradients.MethodsData collection43 10 × 10 m plots were located on limestone anddolomite substrate around two hills of the Sierra deCartagena (Murcia Region, SE Spain), with every expo-sition (N, NE, E, SE, etc.) represented. Topographicalvariation was represented in the sample as well (seeFerrer Castan 1994 for sampling details). On the other
Databáze: OpenAIRE
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