TBI Vietnam

Ecological mechanisms of secondary succession in Vietnamese forests

Photo: Photosynthesis measurements in field
Overall Objective:
Improve the ecological understanding of the development of the structure and composition of the secondary forest in Vietnam.
Specific Objectives
1. To assess the relative importance of different growth characteristics of species in determining whether they become dominant, persist as subordinates or disappear during different stages of succession;
2. To get insight in the planting conditions and species characteristics that determine the success or failure of enrichment planting
Output:
-A dynamic growth model will be developed to study regeneration in forests. This model will integrate light capture and photosynthesis with other growth characteristics, e.g. respiration, mass allocation and leaf and branch turnover.
-Data collection on height, leaf area, light distribution, leaf photosynthetic characteristics and leaf- and branch turnover for a number of individual plants of species that range from early pioneers to climax species.
-The project will be finalized with the writing of a PhD thesis and a series of articles.
Status

This is an ongoing project running from April 2004 - March 2008.

Time schedule of the project (from 2005 onwards)
Time Activity
December 2004-February 2005 Data and laboratory analyses in Utrecht, preparations for field work
March-October 2005 Fieldwork Bach Ma NP and Hai Van area. Fieldwork 4 students from UU (March-June).
November 2005 - February 2006 Data and laboratory analyses in Utrecht, preparations for field work
March - October 2006 Field work in Vietnam
November 2006-March 2008
Data and laboratory analyses in Utrecht, modeling, writing PhD-thesis and articles

Photo: Measuring 2 competing pioneer species in field in Khe Tre, TTH province, Vietnam
Project Outline
In essence, forest succession is the continuous replacement of tree species, starting with early pioneer (light-demanding) shrubs and trees, which are then gradually replaced by longer-lived pioneer and climax (shade-tolerant) tree species. Secondary forest succession diverts into various directions. Some species become dominant while others become subordinate or even disappear from the vegetation. An intriguing ecological question is then 1) How and why do certain species become dominant while others disappear at certain stages of succession? and derived from this 2) What causes succession to divert in different directions or to stagnate? Answering these questions requires a fundamental understanding of the ecological mechanisms that determine forest succession; how different species adjust both morphologically and physiologically to changes that occur during succession.

The research group of Plant Ecology at Utrecht University (the Netherlands) has developed a model with which it is possible to perform this analysis. The model however was designed purely for herbaceous stands. Understanding secondary forest succession requires an approach that integrates light capture and photosynthesis into a dynamic growth model, including such aspects as, leaf and branch turn over, whole plant respiration and stem mass density. The model will therefore be adapted to forests.

Information obtained in field studies in secondary forests and plantation sites in Vietnam will be used to develop the new model. Vietnam has lost most of its forests over the last 60 years. Much of the remaining forests are degraded and natural forest regeneration through succession is often inhibited. Natural forest regeneration is an important way to increase forest cover. Enrichment planting of native tree species in secondary forests is often used to stimulate forest succession, but many attempts have failed. Using the model, we contribute both to ecological understanding of forest succession and to improved forest regeneration in Vietnam and elsewhere.

More information
Partners

Forest Science Institute of Vietnam; Utrecht University, the Netherlands; and Hue University, Vietnam

The research will be executed at the Plant Ecology group at Utrecht University and will be carried out within the framework of the TBI- Vietnam Programme.

For this project, Utrecht University works together in Vietnam with the Research Staff of Bach Ma N.P. (Dr. N.V.Nhon and his colleagues), the FSIV (Prof. dr. N.H.Nghia's group) and Hue University (Dr. N.Q.Linh's group). For the modelling aspects, Utrecht University will continue a long-standing and successful cooperation with Prof. dr. T. Hirose's group in Sendai, Japan. Several links of all our other cooperative contacts with research groups in the Netherlands and internationally will be available for aspects of this project as desirable.
Contact: Ms Marijke van Kuijk (Utrecht University) is working as a PhD student on this project. Contact: Dr Niels P. van Anten, Associate professor at Department of Plant Ecology (Utrecht University), is presently supervising Ms. Marijke van Kuijk.