Wiegand, Kerstin

[["dc.bibliographiccitation.firstpage","807"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Journal of Ecology"],["dc.bibliographiccitation.lastpage","820"],["dc.bibliographiccitation.volume","96"],["dc.contributor.author","Getzin, Stephan"],["dc.contributor.author","Wiegand, Thorsten"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","He, Fangliang"],["dc.date.accessioned","2017-09-07T11:44:40Z"],["dc.date.available","2017-09-07T11:44:40Z"],["dc.date.issued","2008"],["dc.description.abstract","1. The spatial pattern of tree species retains signatures of factors and processes such as dispersal, available resource patches for establishment, competition and demographics. Comparison of the spatial pattern of different size classes can thus help to reveal the importance and characteristics of the underlying processes. However, tree dynamics may be masked by large-scale heterogeneous site conditions, e.g. when the restricting size of regeneration sites superimposes emergent patterns. $\\backslash$\\backslash. Here we ask how environmental heterogeneity may influence the spatial dynamics of plant communities. We compared the spatial patterns and demographics of western hemlock in a homogeneous and a heterogeneous site of old-growth Douglas-fir forests on Vancouver Island using recent techniques of point pattern analysis. We used homogeneous and inhomogeneous K- and pair-correlation functions, and case-control studies to quantify the change in spatial distribution for different size classes of western hemlock. $\\backslash$\\backslash. Our comparative analyses show that biological processes interacted with spatial heterogeneity, leading to qualitatively different population dynamics at the two sites. Population structure, survival and size structure of western hemlock were different in the heterogeneous stand in such a way that, compared to the homogeneous stand, seedlings were more clustered, seedling densities higher, seedling mortality lower, adult growth faster and adult mortality higher. Under homogeneous site conditions, seedling survival was mainly abiotically determined by random arrival in small gaps with limiting light. At the heterogeneous site, seedling densities and initial survival were much higher, leading to strong density-dependent mortality and selection for faster growing individuals in larger size classes. We hypothesise that the dynamics of the heterogeneous stand were faster due to asymmetric competition with disproportionate benefit to taller plants. $\\backslash$\\backslash. Synthesis. Our study supports the hypothesis that successional dynamics are intensified in heterogeneous forest stands with strong spatial structures and outlines the importance of spatial heterogeneity as a determinant of plant population dynamics and pattern formation."],["dc.identifier.doi","10.1111/j.1365-2745.2008.01377.x"],["dc.identifier.gro","3148946"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5589"],["dc.language.iso","en"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.status","public"],["dc.notes.submitter","chake"],["dc.relation.issn","0022-0477"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.subject.gro","Case-control"],["dc.subject.gro","Dispersal strategies"],["dc.subject.gro","Inhomogeneous pair-correlation function"],["dc.subject.gro","Large-scale heterogeneity"],["dc.subject.gro","Point pattern analysis"],["dc.subject.gro","Succession"],["dc.subject.gro","Western hemlock"],["dc.title","Heterogeneity influences spatial patterns and demographics in forest stands"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","318"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Journal of Vegetation Science"],["dc.bibliographiccitation.lastpage","327"],["dc.bibliographiccitation.volume","27"],["dc.contributor.author","Nguyen, Hong Hai"],["dc.contributor.author","Uria-Diez, Jaime"],["dc.contributor.author","Wiegand, Kerstin"],["dc.date.accessioned","2017-09-07T11:44:38Z"],["dc.date.available","2017-09-07T11:44:38Z"],["dc.date.issued","2015"],["dc.description.abstract","Questions What are the prevailing types of intraspecific spatial distributions and interspecific association patterns at species and life stage levels of trees in a tropical rain forest? Which ecological processes could structure these patterns? Possible processes include dispersal limitation, self‐thinning, facilitation and competition between species and life stages. Location A tropical broad‐leaved forest in north‐central Vietnam. Methods We used univariate and bivariate pair‐correlation functions to investigate the spatial distribution and association patterns of 18 abundant tree species. To disentangle first‐ and second‐order effects, we used a scale separation approach with the heterogeneous Poisson process as null model. Results (1) Sixteen of 18 species had aggregated patterns at various scales and regardless of their abundance. (2) Significant and aggregated patterns were found in 64% of all specific life stages. (3) At scales up to 15 m, 12.4% species pairs showed significant associations, among that 71% were spatial attractions, 5% were spatial repulsions and 24% were non‐essential interactions. (4) In different life stage associations, attractions (81%) predominated over repulsions (19%) at small scales of up to 15 m. Conclusions Our findings provide evidence that dispersal limitation may regulate the spatial patterns of tree species. Moreover, positive spatial associations between tree species and life stages suggest the presence of species herd protection and/or facilitation in this forest stand, while the persistence of intraspecific aggregation through life stages suggests a very late onset or even absence of self‐thinning. Habitat heterogeneity plays an important role for species distribution patterns, and the spatial segregation occurs at a scale around 15 m in this forest."],["dc.identifier.doi","10.1111/jvs.12361"],["dc.identifier.gro","3148941"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5583"],["dc.language.iso","en"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.status","public"],["dc.notes.submitter","chake"],["dc.relation.issn","1100-9233"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.subject.gro","Dispersal limitation"],["dc.subject.gro","Neutral theory"],["dc.subject.gro","Pair-correlation function"],["dc.subject.gro","Point pattern analysis"],["dc.subject.gro","Self-thinning"],["dc.subject.gro","Spatial pattern"],["dc.subject.gro","Species association"],["dc.subject.gro","Species herd protection"],["dc.subject.gro","Tropical evergreen forest"],["dc.subject.gro","Vietnam"],["dc.title","Spatial distribution and association patterns in a tropical evergreen broad-leaved forest of north-central Vietnam"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","309"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Journal of Tropical Forest Science"],["dc.bibliographiccitation.lastpage","319"],["dc.bibliographiccitation.volume","26"],["dc.contributor.author","Nguyen, Hong Hai"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","Getzin, Stephan"],["dc.date.accessioned","2017-09-07T11:50:52Z"],["dc.date.available","2017-09-07T11:50:52Z"],["dc.date.issued","2014"],["dc.description.abstract","Streblus macrophyllus is a shade-tolerant and subcanopy tree species common to tropical evergreen forests in northern Vietnam. However, its ecology is poorly known. We used spatial point pattern analysis to describe the spatial arrangement of tree individuals within a forest community dominated by S. macrophyllus. All individual trees with diameter at breast height larger than 2.5 cm in a 1-ha plot were mapped and measured. The overall pattern of this species was a regular distribution at scales up to 2 m. Its juveniles and subadults were strongly aggregated, but adult trees were regular at scales of up to 3 m, implying evidence of density dependent thinning. The spatial pattern of S. macrophyllus strongly affected the patterning of the whole plot. In S. macrophyllus, juveniles and subadults were similarly distributed relative to adults and showed additional clumping independent of the adults. The overall interspecific association between adults of other species and S. macrophyllus at different life-history stages also showed independence. We conclude that S. macrophyllus is a predominant competitor within the community and it follows a gap-phase regeneration mode."],["dc.identifier.gro","3147838"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5164"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.subject","Point pattern analysis forest community gap-phase regeneration mode intra- and interspecific associations"],["dc.subject.gro","Forest community"],["dc.subject.gro","Gap-phase regeneration mode"],["dc.subject.gro","Intra- and interspecific associations"],["dc.subject.gro","Point pattern analysis"],["dc.title","Spatial patterns and demographics of Streblus macrophyllus trees in a tropical evergreen forest, Vietnam."],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","355"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Acta Oecologica"],["dc.bibliographiccitation.lastpage","364"],["dc.bibliographiccitation.volume","33"],["dc.contributor.author","Moustakas, Aristides"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","Getzin, Stephan"],["dc.contributor.author","Ward, David"],["dc.contributor.author","Meyer, Katrin M."],["dc.contributor.author","Guenther, Matthias"],["dc.contributor.author","Mueller, Karl-Heinz"],["dc.date.accessioned","2017-09-07T11:52:23Z"],["dc.date.available","2017-09-07T11:52:23Z"],["dc.date.issued","2008"],["dc.description.abstract","Nearest tree neighbour distances and the tree spatial formation on a large scale over time and space replicates were examined. The study was conducted in a natural savanna ecosystem in the Southern Kalahari, South Africa. Nearest tree neighbour and point pattern analysis methods were used to investigate changes in the spatial pattern of trees in two plots. Trees larger than 2 m canopy diameter were mapped. We used aerial photographs of the study area from 1940, 1964, 1984, 1993, and a satellite image from 2001 to follow two plots over time. Field work was carried out too for classification accuracy. We were able to identify and individually follow over 2400 individual trees from 1940 until 2001. Nearest neighbour analysis results indicate that dead trees were on average closer to their nearest neighbouring trees than living trees were to their neighbours. Most dead trees were on average 6 m from their nearest neighbours, while most living trees were about 20 m apart. Point pattern analysis results show a cyclical transition from clumped to random and sequentially to regular tree spacing. These transitions were not correlated across two plots. Generally, decreases in small-scale clumping coincided with periods of high mortality. Our findings show that regular, clumped, and random tree pattern can occur, pending on time, location, and scale within the location."],["dc.identifier.doi","10.1016/j.actao.2008.01.008"],["dc.identifier.gro","3148903"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5540"],["dc.language.iso","en"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.issn","1146-609X"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.subject.gro","Acacia erioloba"],["dc.subject.gro","Long-term study"],["dc.subject.gro","Nearest neighbour analysis"],["dc.subject.gro","Point pattern analysis"],["dc.subject.gro","Savanna"],["dc.subject.gro","Spatial patterns"],["dc.subject.gro","Tree mortality"],["dc.subject.gro","Tree size"],["dc.subject.gro","Tree-tree competition"],["dc.title","Spacing patterns of an Acacia tree in the Kalahari over a 61-year period: How clumped becomes regular and vice versa"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1823"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Ecology"],["dc.bibliographiccitation.lastpage","1834"],["dc.bibliographiccitation.volume","96"],["dc.contributor.author","Punchi-Manage, Ruwan"],["dc.contributor.author","Wiegand, Thorsten"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","Getzin, Stephan"],["dc.contributor.author","Huth, Andreas"],["dc.contributor.author","Gunatilleke, C. V. Savitri"],["dc.contributor.author","Gunatilleke, I. A. U. Nimal"],["dc.date.accessioned","2017-09-07T11:52:23Z"],["dc.date.available","2017-09-07T11:52:23Z"],["dc.date.issued","2015"],["dc.description.abstract","Interactions among neighbors influence plant performance and should create spatial patterns in local community structure. In order to assess the role of large trees in generating spatial patterns in local species richness we used the individual species-area relationship (ISAR) to evaluate the species richness of trees of different size classes (and dead trees) in neighborhoods with varying size around large trees of different focal species. To reveal signals of species interactions we compared the ISAR function of the individuals of focal species with that of randomly selected nearby locations. We expected that large trees should strongly affect the community structure of smaller trees in their neighborhood, but that these effects should fade away with increasing size class. Unexpectedly we found that only few focal species showed signals of species interactions with trees of the different size classes and that this was less likely for less abundant focal species. However, the few and relatively weak depa..."],["dc.identifier.doi","10.1890/14-1477.1"],["dc.identifier.gro","3148901"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5538"],["dc.language.iso","en"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.status","public"],["dc.notes.submitter","chake"],["dc.relation.issn","0012-9658"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.subject.gro","Independence null model"],["dc.subject.gro","Individual species-area relationship"],["dc.subject.gro","Neighborhood diversity"],["dc.subject.gro","Point pattern analysis"],["dc.subject.gro","Sinharaja tropical forest"],["dc.subject.gro","Spatial scale"],["dc.subject.gro","Stochastic dilution"],["dc.title","Neighborhood diversity of large trees shows independent species patterns in a mixed dipterocarp forest in Sri Lanka"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]