Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity
Date
2018
Journal Title
Journal ISSN
Volume Title
Publisher
SpringerOpen
Abstract
Background: Species turnover is typically measured by partitioning diversity components into alpha and pairwise
beta diversity. However, alpha and beta components cannot express the full spectrum of multiple-site compositional
turnover. To this end, zeta diversity has been proposed as an extended framework to allow complete biodiversity
partitioning and to measure multiple-site species turnover. We use a zeta-diversity framework to explore the
turnover and potential community assembly processes of an African Montane Forest.
Methods: Using a 20 m grid, we explore the species turnover in a 4.55 ha forest plot located in the Garden
Route National Park of South Africa, with 47 and 27 canopy and sub-canopy tree species in the regional pool.
We first calculate how zeta diversity declines and how the probability of retention of species with particular
occupancies changes with increasing zeta orders (i.e. the number of sites [grid cells] involved in the calculation). Using
null models with row sums and column sums constrained respectively, we explore whether species turnover is driven
by mechanisms of ecological differences (species-specific occupancies) or habitat heterogeneity (site-specific alpha
diversity and thus environmental filters).
Results: The decline of zeta diversity with zeta order followed a power law; that is, the probability of retention increased
with species occupancies, suggesting common species being more likely to be discovered in extra sites. The null model
retaining row sums (species’ occupancy) of the species-by-site matrix recreated perfectly the decline of zeta diversity,
while the null model of habitat heterogeneity (retaining column sums) was rejected. This suggests that mechanisms
driving species-specific occupancies (i.e. ecological differences between species) dictate the multi-site species turnover
in the community. The spatial patterns of zeta diversity revealed little spatial structuring forces, supporting a fine-grain
structure in these southern Cape forests.
Conclusions: The framework of zeta diversity revealed mechanisms driving the large discrepancies in the occupancy
among species that are behind the species turnover in the African Montane forest plot. Future studies could further
link species turnover to spatial distance decay. Environmental filters and temporal turnover from landscape
demography could bring a cohesive understanding of community assembly in these unique forest ecosystems.
Description
CITATION: Hui, C., Vermeulen, W. & Graham D. 2018. Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity. Forest Ecosystems, 5:15, doi:10.1186/s40663-018-0135-1.
The original publication is available at https://forestecosyst.springeropen.com
The original publication is available at https://forestecosyst.springeropen.com
Keywords
Species turnover, Diversity partitioning, Zeta diversity, Forests and forestry -- South Africa
Citation
Hui, C., Vermeulen, W. & Graham D. 2018. Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity. Forest Ecosystems, 5:15, doi:10.1186/s40663-018-0135-1