Population dynamics, disturbance, and pattern evolution: Identifying the fundamental scales of organization in a model ecosystem
Authored by Thorsten Wiegand, KA Moloney, SJ Milton
Date Published: 1998
DOI: 10.1086/286172
Sponsors:
UFZ-Centre for Environmental Research
Platforms:
No platforms listed
Model Documentation:
Other Narrative
Flow charts
Mathematical description
Model Code URLs:
Model code not found
Abstract
We used auto- and cross-correlation analysis and Ripley's K-function
analysis to analyze spatiotemporal pattern evolution in a spatially
explicit simulation model of a semiarid shrubland (Karoo, South Africa)
and to determine the impact of small-scale disturbances on system
dynamics. Without disturbance, local dynamics were driven by a pattern
of cyclic succession, where ``colonizer{''} and ``successor{''} species
alternately replaced each other. This results in a strong pattern of
negative correlation in the temporal distribution of colonizer and
successor species. As disturbance rates were increased, the relationship
shifted from being negatively correlated in time to being positively
correlated-the dynamics became decoupled from the ecologically driven
cyclic succession and were increasingly influenced by abiotic factors
(e.g., rainfall events). Further analysis of the spatial relationships
among colonizer and successor species showed that, without disturbance, periods of attraction and repulsion between colonizer and successor
species alternate cyclically at intermediate spatial scales. This was
due to the spatial ``memory{''} embedded in the system through the
process of cyclic succession. With the addition of disturbance, this
pattern breaks down, although there is some indication of increasing
ecological organization at broader spatial scales. We suggest that many
of the insights that can be gained through spatially explicit models
will only be obtained through a direct analysis of the spatial patterns
produced.
Tags
spatial pattern
South-africa
Species-diversity
Alpine abies forests
Arid karoo
Seedling establishment
Nitrogen availability
Serpentine
grassland
Gopher disturbance
Germination sites