Global change in tropical forests
Abstract
Enormous research efforts are made to understand how plants and ecosystems respond to rising atmospheric CO2-concentrations, but also to other drivers of global change such as changes in climate and deposition of nitrogen. While it is mostly unknown how these have already affected tropical forest over the past decades, detecting and distinguishing the impacts of global change is most important to understand past and predict future changes. Currently tropical forests appear to act as major carbon sinks, but will not continuously do so forever. Experimental studies from other forests suggest that a fertilizing effect of CO2 is strongest when temperature, water and nutrients are least limiting, but the complexity and size of mature tropical forests has so far prevented free air CO2-enrichment studies in this important biome. Alternatively, throughout the tropics repeated forest inventories, originally designed to study forest dynamics, growth and function, are used to detect and analyse long-term changes potentially related to global change. These data show evidence of increased tree growth, turnover and changing species composition, but have met considerable discussion. One problem is that measurements rarely go back more than three decades and are potentially subject to bias from initial site selection or disturbance. Annual growth rings are widely used to analyse environmental impact, including global change, on temperate trees. Tree rings have been little used in tropical trees, although a number of species do produce regular rings that can be used to analyse past trends in climate, tree physiology, and growth as a reaction to rising CO2 levels and other factors over the past 100+ years. Tree rings appear to be the best, or indeed the only option for a range of research questions which the project will address. The main questions are if growth has increased in the past decades, and which global driver is responsible for changes in growth. We propose to sample increment cores from five long-term forest plots in Panama, India, Thailand and Australia, representing a gradient from strong to moderate seasonality of rainfall and total annual rainfall. Trees from each species will be selected to represent different ages and sizes, to be able to distinguish ontogenetic effects from long-term environmental changes. Increment cores will be analysed for ring width (growth), wood density (may be affected by CO2 and possibly growth, and is important to relate diameter growth to biomass), cellulose 13C (indicating water use efficiency and leaf internal CO2 concentrations), 18O, 2H (climate signals), wood 15N and N concentration (changes in nitrogen deposition or limitation). In addition to revealing long-term trends related to global change, short-term changes in growth will show how different species respond to inter-annual changes in climate, and analysing many trees from one site provides insights in the long-term dynamics of tropical forests. The project will be an important contribution to understand how tropical forests have responded to global change in the past and are likely to do in the future and provide insight into short-term growth dynamics.
keywords global change tropical forest stable isotopes tree ring
Publikationen
Lianas versus trees : analysing liana abundance in an Australian tropical rainforest nine years after hurricane disturbance
Autoren: Hietz, P., Hietz-Seifert, U., Liddell, M. Jahr: 2009
Conference & Workshop proceedings, paper, abstract
Wood density and its radial variation in six canopy tree species differing in shade-tolerance in western Thailand
Autoren: Nock C.A., Geihofer D., Grabner M., Baker P., Bunyavejchewin S., Hietz P. Jahr: 2009
Conference & Workshop proceedings, paper, abstract
Long-term and age-related isotope trends in pristine tropical forests.
Autoren: Hietz, P., Nock, C., Leis, A., Wanek, W. Jahr: 2009
Conference & Workshop proceedings, paper, abstract
Isotope analysis to reconstruct environmental change and tree responses in tropical forests
Autoren: Hietz P., Nock C., Wanek W., Baker P. Jahr: 2010
Conference & Workshop proceedings, paper, abstract
Sleeping beauties are awakening: the story of the African herbarium of the Botanic Garden Meise, Belgium
Autoren: Janssens, S.; Verstraete, B.; Hietz, P.; Dakis-Yaoba, O.; Fayolle, A.; Delvaus, C.; Beeckman, H.; de Ridders, M.; Bogaerts, A; de Smedt, S.;Stoffelen P., Janssens, S.; Verstraete, B.; Hietz, P.; Dakis-Yaoba, O.; Fayolle, A.; Delvaus, C.; Beeckman, H.; de Ridders, M.; Bogaerts, A.; de Smedt, S.; Stoffelen, P.; Jahr: 2016
Conference & Workshop proceedings, paper, abstract
Intra- and interspecific variation in wood functional traits of tropical trees
Autoren: Hietz, P.; Scheffknecht, S. Jahr: 2016
Conference & Workshop proceedings, paper, abstract
Changes in functional leaf traits of Central African rainforest trees
Autoren: Verstraete, B.; Helsen, K.; Janssen, S.; Delvaux, C.; Beeckman, H.; Stoffelen, P.; Hietz, P. Jahr: 2016
Conference & Workshop proceedings, paper, abstract
Project staff
Peter Hietz
Univ.Prof. Mag.rer.nat. Dr.rer.nat. Peter Hietz
peter.hietz@boku.ac.at
Tel: +43 1 47654-83110
Project Leader
01.04.2007 - 29.02.2012
Michael Grabner
Priv.-Doz. Dipl.-Ing. Dr.nat.techn. Michael Grabner
michael.grabner@boku.ac.at
Tel: +43 1 47654-89128
Sub Projectleader
01.04.2007 - 29.02.2012
BOKU partners
External partners
Royal Forest Department
Sarayudh Bunyavejchewin
partner
CSIRO Tropical Forest Research Centre
Daniel Metcalfe
partner
Monash University
Patrick Baker
partner
Smithsonian Tropical Research Institute
Richard Condit Joseph Wright
partner
Indian Institute of Sciences, Center for Ecological Studies
Raman Sukumar
partner
Joanneum Research
Albrecht Leis
partner
Universidad Nacional Autonoma de Mexico, Centro de Investigaciones en Ecosistemas
Miguel Martínez
partner
Utrecht University
Niels Anten
partner
University of Vienna, Institute of Plant Physiology, Department of Vegetation Ecology and Conservation Biology
Wolfgang Wanek
sub-coordinator