Worbes, Martin

[["dc.bibliographiccitation.firstpage","442"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Trees"],["dc.bibliographiccitation.lastpage","451"],["dc.bibliographiccitation.volume","18"],["dc.contributor.author","Fichtler, E."],["dc.contributor.author","Trouet, V."],["dc.contributor.author","Beeckman, H."],["dc.contributor.author","Coppin, P."],["dc.contributor.author","Worbes, Martin"],["dc.date.accessioned","2018-11-07T10:47:59Z"],["dc.date.available","2018-11-07T10:47:59Z"],["dc.date.issued","2004"],["dc.description.abstract","Tree-ring studies contribute worldwide to the understanding of climate and its relation to tree growth. Long tree-ring chronologies serve as climate proxies for the reconstruction of past, pre-instrument climate and its recent change. In tropical regions, the availability of exactly dated tree-ring chronologies is limited. The dendroclimatic potential of two dominant species from dry forests in northern Namibia was examined in the study presented in this paper. Both species (Burkea africana Hook and Pterocarpus angolensis DC) were sampled at two sites (ca. 900 km apart), and the response to several climatic variables, including ENSO indices, is studied. All specimens showed distinct growth rings and cross-dating between radii was successful for all trees. Species-specific mean curves were built for both sites. The mean curves of different species of the same site synchronised significantly, allowing the construction of a site-specific chronology. Synchronisation between sites was not possible, but spectral analysis of the chronologies implied that both show similar long-term (6.7 year) oscillation patterns. B. africana is more sensitive to rainfall variation than P. angolensis at both sites. Growth response to rainfall was positive, but a time-lag in the reaction occurred between the sites, corresponding to the time-lag of the beginning of the rainy season. Air temperature showed a negative correlation with stem increment at both sites. The response at the westernmost site to two ENSO indices indicates a tree growth decrease during El Nino years, which are generally dry in southern Africa."],["dc.identifier.doi","10.1007/s00468-004-0324-0"],["dc.identifier.isi","000222943100009"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/48092"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","0931-1890"],["dc.title","Climatic signals in tree rings of Burkea africana and Pterocarpus angolensis from semiarid forests in Namibia"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","119"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","IAWA Journal"],["dc.bibliographiccitation.lastpage","140"],["dc.bibliographiccitation.volume","33"],["dc.contributor.author","Fichtler, Esther"],["dc.contributor.author","Worbes, Martin"],["dc.date.accessioned","2018-11-07T09:15:16Z"],["dc.date.available","2018-11-07T09:15:16Z"],["dc.date.issued","2012"],["dc.description.abstract","For a better understanding of the influence of external growth factors on the wood structure, samples of 139 tropical trees were analysed across plant families and a wide climatic gradient. For all samples a unique data set on climate, site and forest stand conditions is available. Different vessel variables as well as the relative cross-sectional area of vessel, parenchyma and fibre tissue were studied in individual tree rings of varying sizes. High within-species and within-site variation of wood anatomical variables was observed which was higher than inter-species and -site variation. In addition, between-ring variation within many individuals was higher than variation between individuals. The differences within individuals show how trees can adapt or adjust to environmental variability and can provide information about the plasticity of a species under changing environmental conditions. The variable 'vessel diameter' showed the strongest and most significant correlations to other wood anatomical variables, but also to climate parameters and tree morphology. Thereby tree size (DBH & height) and crown exposure to light had the strongest impact on vessel size and consequently on hydraulic stem architecture. General climate conditions only showed a weak influence on vessel variables. The principal component analyses revealed a strong influence of tree morphology and a weaker influence of climate on the hydraulic stem architecture. In contrast the general climatic site conditions strongly influenced fibre and parenchyma tissue."],["dc.description.sponsorship","German Federal Environmental Foundation (DBU)"],["dc.identifier.isi","305198500002"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/27641"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Int Assoc Wood Anatomists"],["dc.relation.issn","0928-1541"],["dc.title","WOOD ANATOMICAL VARIABLES IN TROPICAL TREES AND THEIR RELATION TO SITE CONDITIONS AND INDIVIDUAL TREE MORPHOLOGY"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","527"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Tree Physiology"],["dc.bibliographiccitation.lastpage","536"],["dc.bibliographiccitation.volume","33"],["dc.contributor.author","Worbes, Martin"],["dc.contributor.author","Blanchart, Sofie"],["dc.contributor.author","Fichtler, Esther"],["dc.date.accessioned","2018-11-07T09:25:00Z"],["dc.date.available","2018-11-07T09:25:00Z"],["dc.date.issued","2013"],["dc.description.abstract","Drought tolerance is a key factor for the establishment and survival of tree species in tropical ecosystems. Specific mechanisms of drought resistance can be grouped into four functional ecotypes based on differences in leaf fall behavior: deciduous, brevi-deciduous, stem succulent and evergreen. To identify the key factors influencing phenology and cambial activity and thus drought tolerance, we tested the stomatal conductance, leaf water potential and stable carbon isotopes in the leaves and wood of 12 species from a tropical dry forest in Costa Rica. With wood anatomical techniques, we further studied seasonal cambial activity and a suite of wood traits related to water transport for each of the functional ecotypes. Using a principal component analysis, we identified two groups of variables that can be related to (i) hydraulic conductivity and (ii) control of transpiration and water loss. Hydraulic conductivity is controlled by vessel size as the limiting variable, water potential as the driving force and wood density as the stabilizing factor of the anatomical structure of an effective water transport system. Stomatal control plays a major role in terms of water loss or saving and is the dominant factor for differences in phenological behavior. Stem succulent species in particular developed a rarely identified but highly effective strategy against drought stress, which makes it a successful pioneer species in tropical dry forests."],["dc.identifier.doi","10.1093/treephys/tpt028"],["dc.identifier.isi","000319430900008"],["dc.identifier.pmid","23629581"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/29967"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Oxford Univ Press"],["dc.relation.issn","0829-318X"],["dc.title","Relations between water balance, wood traits and phenological behavior of tree species from a tropical dry forest in Costa Rica-a multifactorial study"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","306"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Biotropica"],["dc.bibliographiccitation.lastpage","317"],["dc.bibliographiccitation.volume","35"],["dc.contributor.author","Fichtler, E."],["dc.contributor.author","Clark, D. A."],["dc.contributor.author","Worbes, Martin"],["dc.date.accessioned","2018-11-07T10:36:21Z"],["dc.date.available","2018-11-07T10:36:21Z"],["dc.date.issued","2003"],["dc.description.abstract","In an old-growth tropical wet forest at La Selva, Costa Rica, we combined radiocarbon (C-14) dating and tree-ring analysis to estimate the ages of large trees of canopy and emergent species spanning a broad range of wood densities and growth rates. We collected samples from the trunks, of 29 fallen, dead individuals. We found that all eight sampled species formed visible growth rings, which varied considerably in distinctiveness. For five of the six species for which we combined wood anatomical studies with C-14-dates (ring ages), the analyses demonstrated that growth rings were of annual formation. The oldest tree we found by direct ring counting was a Hymenolobium mesoamericanum Lima (Papilionaceae) specimen, with an age of ca. 530 years at the time of death. All other sampled individuals, including very large trees of slow-growing species, had died at ages between 200 and 300 years. These results show that, even in an everwet tropical rain forest, tree growth of many species can be rhythmic, with an annual periodicity. This study thus raises the possibility of extending tree-ring analyses throughout the tropical forest types lacking a strong dry season or annual flooding. Our findings and similar measurements from other tropical forests indicate that the maximum ages of tropical emergent trees are unlikely to be much greater than 600 years, and that these trees often die earlier from various natural causes."],["dc.identifier.doi","10.1111/j.1744-7429.2003.tb00585.x"],["dc.identifier.isi","000186644700001"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/45303"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Assoc Tropical Biology Inc"],["dc.relation.issn","0006-3606"],["dc.title","Age and long-term growth of trees in an old-growth tropical rain forest, based on analyses of tree rings and C-14"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","35"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Tree-Ring Research"],["dc.bibliographiccitation.lastpage","49"],["dc.bibliographiccitation.volume","66"],["dc.contributor.author","Fichtler, Esther"],["dc.contributor.author","Helle, Gerhard"],["dc.contributor.author","Worbes, Martin"],["dc.date.accessioned","2018-11-07T08:48:40Z"],["dc.date.available","2018-11-07T08:48:40Z"],["dc.date.issued","2010"],["dc.description.abstract","Although studies on stable-carbon isotopes in trees from temperate zones provide abundant paleoclimatic data, tropical trees are still understudied in this context. Therefore this study examined the variability of intra- and inter-annual stable-carbon isotopic pattern in several tree species from various tropical climates. The delta(13)C Values of samples of 12 broadleaved trees (seven species) from various paleotropical and neotropical sites along a climatic moisture gradient were investigated. The inter-annual variability between species and sites was studied. Further the relationship between delta(13)C and precipitation time series was analyzed. Results show that tropical tree species show a similar variability in carbon isotopic composition as temperate tree species. Significant correlations between annual precipitation and tree-ring delta(13)C time series were negative. Successful crossdating of a tree-ring delta(13)C time series highlights the potential of carbon isotope measurements for tropical tree-ring analytical studies. Tropical broadleaved trees are able to capture a carbon isotopic signal in their annual rings even under everwet conditions and show good potential for paleoclimatic research."],["dc.description.sponsorship","Deutsche Bundesstiftung Urnwelt"],["dc.identifier.doi","10.3959/2008-20.1"],["dc.identifier.isi","000274162400003"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/21271"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Tree-ring Soc"],["dc.relation.issn","1536-1098"],["dc.title","STABLE-CARBON ISOTOPE TIME SERIES FROM TROPICAL TREE RINGS INDICATE A PRECIPITATION SIGNAL"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]