Sustainable management of dipterocarp forests in the Philippines

  • Author / Creator
    Chechina, Mariya
  • Southeast Asian dipterocarp forests are highly diverse tropical forest communities, with the family Dipterocarpaceae alone comprising hundreds of species. Dipterocarps are remarkable in that they exhibit supra-annual mass flowering events, which occur in irregular intervals of two to ten years, normally involving several dipterocarp species and sometimes including many other plant families as well, a phenomenon known as general flowering event. Dipterocarps are a leading species group on 85% of Southeast Asia’s forested land base and they are also commercially important, representing a quarter of global consumption of tropical timbers. Southeast Asia’s dipterocarp forests are also one of the most threatened tropical ecosystems in the world. Only 16% of the total original forested area remains classified as primary forest in Southeast Asia and less than 6% in the Philippines, which is a focus of this thesis. The overall objective of this thesis is to support and improve reforestation and community forestry initiatives in dipterocarp forests by contributing ecological insight and compiling local community knowledge, and by addressing major impediments to successful forest restoration in Southeast Asia. The first issue is the biology of dipterocarp reproduction that makes it hard to manage natural regeneration as well as reforestation. It is logistically difficult to mobilize resources to collect short lived dipterocarp seed without knowing in advance when flowering will occur. This thesis research investigates what environmental factors drive dipterocarp mass flowering and tests alternative resource accumulation and trigger models to predict mass flowering. Using a variety of candidate predictor variables (precipitation, cloud cover, minimum temperature and El Niño indices) a plausible environmental trigger could not be found (median AUCs around 0.55 indicating near random predictions), while the best resource accumulation model had a median AUC of 0.70, which could be improved to 0.75 when the date of previous flowering was included in the model. Further, the analysis revealed that a simple resource accumulation by individual trees can cause inter- and intraspecific flowering synchronization leading to community-wide general flowering events. The second issue is a lack of knowledge of which dipterocarps and which other native species are suitable for reforestation. Community based forest management programs typically use readily available exotic species that may not be desired by the local communities. Choosing species for reforestation programs or community forestry in species-rich tropical rainforest ecosystems is a complex task. Reforestation objectives, social preferences, and ecological attributes must be balanced to achieve landscape restoration, timber production, or community forestry objectives. In a case study for an upland tropical rainforest in the Philippines, socioeconomic preference in five forest-dependent communities were surveyed. In addition, ecological suitability of tree species for open-field plantations was inferred from growth rates, density and frequency of native tree species in long-term monitoring plots. Notably, ecological suitability indicators and socioeconomic preference ranks were generally negatively correlated, with few species being classified as both ecologically suitable and socioeconomically valuable. The results also highlight that reforestation species must be carefully chosen, and that species-rich tropical rainforests are not an easily renewable natural resource. Secondary and planted forests do not serve socioeconomic needs of forest-dependent communities as do original native forests

  • Subjects / Keywords
  • Graduation date
    Fall 2015
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
  • Specialization
    • Forest Biology and Management
  • Supervisor / co-supervisor and their department(s)
  • Examining committee members and their departments
    • Nielsen, Scott (Renewable Resources)
    • Davidson, Debra (Resource Economics and Environmental Sociology)
    • Hacke, Uwe (Renewable Resources)
    • David Olefeldt (Renewable Resources)
    • Walters, Bradley B. (Geography and Environment, Mount Allison University)
    • Parkins, John (Resource Economics and Environmental Sociology)