FORRU - Lowland forests

This project is an independant research project carried out by Cherdsak Kuaraksa, sponserored by the IFS as an early career grant. Cherdsak's work is addressing one of the most serious environmental problems of the 21st century; the destruction of tropical forests and their associated rich biodiversity. In large deforested areas, the natural processes of succession that usually lead to forest regeneration can no longer be relied upon. Lack of seed trees in the landscape and the extirpation of seed-dispersing animals mean that the seeds of rare primary forest trees are not usually transported into deforested areas. Those few that are dispersed, face competition with exotic weeds, browsing by cattle and fire, which all prevent seedlings from beoming established to eventually regenerate the forest ecosystem. Trees with large seeds and fleshy fruits are particularly at risk, since they require large vertebrate frugivores, for example elephants, rhinos and wild catte, for their dispersal and these have mostly been hunted out over most of their former ranges.

Whilst forest restoration work by FORRU using the framework tree method has been partially successful, the absence of recovery of rare or large-seeded tree species in framework plots requires further attention. For rare forest tree species, very little is known about their reproductive ecology (the reason why they may be rare). Almost nothing is known about horticultural techniques to propagate them, since most have never been grown in nurseries, and studies of their early establishment in deforested areas have not been carried out. Cherdsak's rare species project, funded by IFS, aims to investigate phenology, propogation and field performance of up to 30 tree species considered to be rare or threatened with extirpation from northern Thailand, particularly those with large seeds.

The objectives of Cherdsak's rare species progect is to develop effective techniques to grow rare forest tree species (or those with limited diserpsal capacity) in order to include them in forest restoration programs by:

Identifying seed sources of such species
Increasing understanding of their reproductive ecology
Determining suitable propagation protocols for them
Establishing field trials to evaluate their performance after planting out in deforested sites.

Known recorded locations for seed sources for rare tree species in northern Thailand
A set of phenological profiles of rare tree species to guide seed collection schedules
A "best practice" guide to the propogataion of rare tree speices based on control experiments
Field trials established in order to determine the field performance of rare tree species.

All information generated by this project will be integrated into a database system, containing phenology, seed germination and seedling growth data as well as initial field performance data for each species. This database will enable production schedules and a best practices guide to be compiled for all species studied. Species entries will include optimal timings for such activities as seed collection, pricking out, standing down and hardening off of trees in the nursery to produce planting stock of a plantable size in time for the start of the rainy season (the optimal planting time) as well as optimal seed pre-treatment and fertilizer treatments etc. Along with suitable images, this information will be compiled into a best practices guide for the propagation of N. Thailand’s rare or threatened tree species and distributed to organizations involved in growing and planting indigenous forest tree species for restoring N. Thailand’s forest ecosystems.