title: Temperature and rainfall strongly drive temporal growth variation in Asian tropical forest trees.
abstract: Climate change effects on growth rates of tropical trees may lead to alterations in carbon cycling of carbon-rich tropical forests. However, climate sensitivity of broad-leaved lowland tropical trees is poorly understood. Dendrochronology (tree-ring analysis) provides a powerful tool to study the relationship between tropical tree growth and annual climate variability. We aimed to establish climate-growth relationships for five annual-ring forming tree species, using ring-width data from 459 canopy and understory trees from a seasonal tropical forest in western Thailand. Based on 183/459 trees, chronologies with total lengths between 29 and 62 years were produced for four out of five species. Bootstrapped correlation analysis revealed that climate-growth responses were similar among these four species. Growth was significantly negatively correlated with current-year maximum and minimum temperatures, and positively correlated with dry-season precipitation levels. Negative correlations between growth and temperature may be attributed to a positive relationship between temperature and autotrophic respiration rates. The positive relationship between growth and dry-season precipitation levels likely reflects the strong water demand during leaf flush. Mixed-effect models yielded results that were consistent across species: a negative effect of current wet-season maximum temperatures on growth, but also additive positive effects of, for example, prior dry-season maximum temperatures. Our analyses showed that annual growth variability in tropical trees is determined by a combination of both temperature and precipitation variability. With rising temperature, the predominantly negative relationship between temperature and growth may imply decreasing growth rates of tropical trees as a result of global warming.
authors.affiliation: Forest Ecology and Forest Management Group, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands, mart.vlam@wur.nl.
authors.forename: Mart
authors.initials: M
authors.lastname: Vlam
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Baker
authors.forename: Sarayudh
authors.initials: S
authors.lastname: Bunyavejchewin
authors.forename: Pieter A
authors.initials: PA
authors.lastname: Zuidema
mesh_terms: D002244:Carbon; D057486:Carbon Cycle; D057231:Climate Change; D016014:Linear Models; D011891:Rain; D013696:Temperature; D013785:Thailand; D014197:Trees / Q000254:growth & development* / Q000502:physiology; D014329:Tropical Climate; D014867:Water
chemical_list: D014867:Water; D002244:Carbon