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CONTRASTING EFFECTS OF MEAN INTENSITY AND TEMPORAL VARIATION OF DISTURBANCE ON A ROCKY SEASHORE
Author(s) -
Bertocci Iacopo,
Maggi Elena,
Vaselli Stefano,
Benedetti-Cecchi Lisandro
Publication year - 2005
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/04-1698
Subject(s) - ecology , disturbance (geology) , variation (astronomy) , environmental science , biology , astrophysics , paleontology , physics
Understanding the extent to which natural assemblages withstand changes in the regime of disturbance has considerable practical and theoretical interest. In this paper we examine the separate and interactive effects of intensity, temporal variation, and spatial extent of disturbance on temporal variance in assemblages of algae and invertebrates of rocky shores in the northwest Mediterranean. Temporal variation of disturbance is a predictor variable in the experiment, while temporal variance in abundance and number of taxa and in structure of assemblages are response variables. Multivariate analyses detected a positive relationship between intensity of disturbance and temporal variance in the structure of assemblages, while temporal variation of disturbance elicited the opposite effect. Univariate analyses conducted on the most abundant taxa revealed idiosyncratic patterns, while temporal variance in mean number of taxa was greatly reduced by disturbance, with no distinction among levels of intensity, temporal variation, or spatial extent. These outcomes suggest caution in interpreting the results of experiments in which intensity and temporal variation of disturbance cannot be separated. Distinguishing between these traits of disturbance may be key to predicting the ecological consequence of environmental fluctuations, including those expected under modified climate scenarios.