Spatiotemporally interactive growth dynamics in selected South African forests: Edaphoclimatic environment, crowding and climate effects

Seydack, Armin H. W.; Durrheim, Graham; Louw, Josua

doi:10.1016/j.foreco.2010.12.017

Cited by 15 publications

(12 citation statements)

References 66 publications

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“…4) display distinct differences in their reactions to competition (Seifert et al 2014). Growth is strongly influenced by light availability for canopy species in the lower canopy and subcanopy levels, while trees at the canopy level of inherently faster growing species usually reach larger sizes and are more responsive to light, with slower growing species occurring below faster growing species and vice versa (Seydack et al 2011). The growth of subcanopy trees of canopy species is also constrained by the proximity of adult trees of the same species, particularly for the two dominant canopy species, viz.…”

Section: Discussionmentioning

confidence: 99%

Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity

Hui

Durrheim

2018

For. Ecosyst.

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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.

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Section: Discussionmentioning

confidence: 99%

Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity

Hui

Durrheim

2018

For. Ecosyst.

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“…These matrix invading canopy species are often considered to be gap opportunists and are geared to occupy upper canopy positions. Physiologically, forest matrix occupants are persistence specialists (stress resistance) under the resource-responsive metabolic performance mode, underpinning persistance capacity and niche specialisation under tropical conditions (Seydack 2000;Seydack et al 2011Seydack et al , 2012.…”

Section: Structure and Diversitymentioning

confidence: 99%

“…Diversity does not only refer to species richness, but to a range of phenomena that determine the heterogeneity within a community, including the diversity of tree sizes and spatial patterns. In general, studies on complex multi-species and highly structured forest ecosystems, such as the Knysna-Amatole forests are relatively scarce (Midgley et al 2002, Midgley & Seydack 2006, Seydack et al 2011. Structure and species diversity are important characteristics of a forest community and a comprehensive description regarding these attributes of the unique Knysna forests is still incomplete.…”

Section: Objectivesmentioning

confidence: 99%

Diversity and production in an Afromontane Forest

et al. 2016

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Background: This contribution evaluates the effect of forest structure and tree species diversity on plot productivity and individual tree growth in the unique Knysna forests in Southern Africa using mapped tree data from an observational study that has been re-measured over a period of 40 years. Methods:The effects of tree species diversity and forest structure on tree growth and forest production are evaluated on three levels of resolution: a) the forest community (canopy, sub-canopy species), b) the subplots (number of trees per ha, skewness of the diameter distribution, diameter coefficient of variation) and c) the immediate neighborhood of selected reference trees ("Mingling", "Dominance", Aggregation" and "Size Variation").Results: An analysis of the community level identified two distinct clusters, one including dominant/canopy species with the highest growth rates and a greater variation of growth, and another cluster which includes the remaining subcanopy species which have a smaller maximum size and lower rates of growth. The area-based structure variables on plot level have a highly significant effect on total basal area growth. However, the effects of forest density and species richness on productivity were not straight forward. Maximum basal area production of about 0.75 m 2 /ha/year is achieved at medium levels of richness (around 20 species per ha) and medium levels of density (around 30 m 2 /ha basal area) using percentile regression estimates. The relative "Dominance" of a selected reference tree had a highly significant effect on individual tree growth on all investigated species. Other neighbourhood structure variables were only occasionally significant or not significant at all. Conclusion:This contribution presents a new theoretical framework for analysing natural forests that includes community, plot and neighborhood variables of forest structure and diversity, and a first specific analysis of the structure and dynamics of the Knysna Afromontane Forest, based on a unique set of longterm observations. The species-area (SAR) model developed in this study, represents a new general approach that can be used to derive a common standard of tree species diversity for different plot sizes, the species richness per hectare.

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“…El anterior es uno de los factores indispensables para la construcción de un modelo de crecimiento de árbol individual, especialmente, si se trata de especies en bosques mixtos e irregulares (Schröder y Gadow, 1999). Sin embargo, ese tipo de estudios se han realizado, sobre todo, en plantaciones de una sola especie, por lo que los relativos a bosques irregulares con más de un taxon son todavía muy escasos (Moravie et al, 1999;Coates et al, 2009;Seydack et al, 2011).…”

Section: Introductionunclassified

Influencia de la competencia en el crecimiento diamétrico de Pinus durangensis Martínez en Durango, México

Colín

Calderón

Corral-Rivas

et al. 2018

RMCF

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Spatiotemporally interactive growth dynamics in selected South African forests: Edaphoclimatic environment, crowding and climate effects

Cited by 15 publications

References 66 publications

Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity

Quantifying multiple-site compositional turnover in an Afrotemperate forest, using zeta diversity

Diversity and production in an Afromontane Forest

Influencia de la competencia en el crecimiento diamétrico de Pinus durangensis Martínez en Durango, México

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