Permanent quadrats: An interface for theory and practice

Abstract

Certain neglected concepts for studying vegetation dynamics are reviewed, particularly the incorporating of temporal and spatial heterogeneity; examples are given. Few studies have been of sufficient length to allow partition of the various types of temporal fluctuation influencing vegetation composition. Studies of changes in spatial pattern with time are similarly few. The formation of patches of vegetation and their change with time (nucleation) may determine the entire spatio-temporal structure of the ecosystem, e.g. vegetation groves in arid zones. Simultaneous study of temporal and spatial heterogeneity is required. Future studies will necessitate higher standards of evidence than previously accepted. The practice of equating a few spatially separated sites having different periods of time since a specific disturbance should not be accepted in the absence of evidence that their potential vegetation dynamics has been similar during those periods.Permanent quadrats with an appropriate experimental design are needed to overcome these problems. The requirements to be met by such a design are discussed, incliading the role of location, contiguity, perturbation or synthetic experimentation and demographic measurement.

Influence of climate and community composition on the population demography of pasture species in semi-arid Australia

“…Vegetation dynamics are influenced by factors that operate either simultaneously or sequentially (Austin 1981). These factors include both the intrinsic properties of the component species populations as expressed in primary succession and regeneration cycles, and extrinsic forcing factors such as climate.…”

Long-Term Studies in Ecology

“…1985) , and similar use of long-term records in vegetation science has been suggested (Beeftink, 1979;Austin , 1981).…”

Journal of Range Management, Volume 53, Number 6 (November 2000)

“…A simple and clear explanation is that where cover before the onset of the hot dry summer was less than 70% (as it was in most 'burn' sub-plots), subsequent changes in cover were greater than in periods of less severe weather. Since data from 'burn' sub-plots were included to demonstrate the potential of the photographic method in monitoring treatment effects through time (Austin 1981), a detailed interpretation of treatment effects is not included here and is the subject of ongoing research.…”