Spatial structure of deciduous forest stands with contrasting human influence in northwest Spain |
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| Authors: | V Rozas R Zas A Solla |
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| Institution: | (1) Departamento de Ecología, CINAM de Galicia, Apdo. 127, 36080 Pontevedra, Spain;(2) Misión Biológica de Galicia, CSIC, Apdo. 28, 36080 Pontevedra, Spain;(3) Ingeniería Técnica Forestal, Universidad de Extremadura, Avenida Virgen del Puerto 2, 10600 Plasencia, Spain |
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| Abstract: | Five contrasting deciduous forest stands were studied to characterize the spatial structural variability in human-influenced
forests. These stands are representative of cultural forest types widely represented in western Europe: one plantation, two
coppices, one wood-pasture forest and one high forest stand. All stems with DBH > 5 cm were measured and mapped, and stem
DBH distributions, spatial structure of DBH, spatial point patterns and spatial associations were analysed. Spatial autocorrelation
for DBH was calculated with Moran’s I correlograms and semivariograms. Complete spatial randomness hypothesis for spatial point patterns, and both independence
and random labelling hypotheses for spatial associations were analysed using Ripley’s K function. The results showed that tree sizes were conditioned by particular former management systems, which determined unimodal
symmetric, positively skewed or compound DBH distributions. Spatial structure was more complex when human influence became
reduced. Coppice stands showed clumped spatial patterns and independence among size classes, as a consequence of sexual and
vegetative establishment of new stems in open areas. The largest clumping intensity was observed in the wood-pasture with
an intermediate disturbance frequency and low inter-tree competition. The high forest stand displayed spatial traits consistent
with the gap-dynamics paradigm, such as clumping of smaller trees, random arrangement of larger trees, negative association
between juveniles and adults, and high structural heterogeneity. It can be expected that after cessation of human interference,
coppices and wood-pastures would evolve to a more heterogeneous structure, probably with a higher habitat and species diversity. |
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| Keywords: | Geostatistics Spatial autocorrelation Moran’ s I coefficient Spatial pattern Null models Random labelling Ripley’ s K function Stand structure |
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