Population Ecology

, Volume 50, Issue 2, pp 227–237

Conservation prospects for threatened Vietnamese tree species: results from a demographic study

  • Pham Duc Chien
  • Pieter A. Zuidema
  • Nguyen Hoang Nghia
Original Article

DOI: 10.1007/s10144-008-0079-3

Cite this article as:
Chien, P.D., Zuidema, P.A. & Nghia, N.H. Popul Ecol (2008) 50: 227. doi:10.1007/s10144-008-0079-3

Abstract

Given that changes in population size are slow, information on future prospects of long-lived tree species is necessarily obtained from demographic models. We studied six threatened tree species in four Vietnamese protected areas: the broad-leaved Annamocarya sinensis, Manglietia fordiana and Parashorea chinensis, and the coniferous Calocedrus macrolepis, Dacrydium elatum and Pinus kwangtungensis. With data from a 2-year field study on recruitment, growth and survival, we constructed matrix models for each species. All species showed continuous regeneration, as indicated by annual seedling recruitment and inverse J-shaped population structures. To evaluate the future prospects of our study species, we calculated three parameters: (1) asymptotic growth rates (λ) from matrix models indicated significant population declines of 2–3%/year for two species; (2) population trajectories for 50–100 years showed slight population declines (0–3%/year) for five species; and (3) the reproductive period required for an adult tree to replace itself was excessive for three of the six species, suggesting that these species presently have insufficient recruitment. Overall agreement of the three parameters was low, showing that reliance on just one parameter is risky. Combining the three parameters we concluded that prospects are good for Dacrydium and Parashorea, worrisome for Annamocarya, Manglietia and Pinus, and intermediate for Calocedrus. We argue that conservation should involve strict protection of (pre-)adult trees, as their survival is crucial for population maintenance in all species (high elasticity). For species with poor demographic prospects, active intervention is required to improve seedling and tree growth, enrich populations with seedlings from controlled germination, and restore habitat. Finally, our study suggests that these conservation measures apply to long-lived trees in general, given that their demography is highly similar. Such measures should be taken before populations decline below critical levels, as long-lived species will respond slowly to management.

Keywords

Conservation strategy Elasticity analysis Matrix population models Population dynamics Protected areas Threatened tree species 

Supplementary material

10144_2008_79_MOESM1_ESM.doc (132 kb)
Conservation prospects for threatened Vietnamese tree species: results from a demographic study (DOC 131 kb)

Copyright information

© The Society of Population Ecology and Springer 2008

Authors and Affiliations

  • Pham Duc Chien
    • 1
    • 2
    • 3
  • Pieter A. Zuidema
    • 1
    • 3
  • Nguyen Hoang Nghia
    • 2
    • 3
  1. 1.Department of Plant Ecology and Biodiversity, Faculty of ScienceUtrecht UniversityUtrechtThe Netherlands
  2. 2.Forest Science Institute of VietnamHanoiVietnam
  3. 3.Tropenbos International Vietnam (TBI)HueVietnam