Summary

Tropical rainforests (TRFs) and tropical montane forests (TMFs) in Sri Lanka play a critically important role in biodiversity conservation and climate change mitigation. They contain a considerable number of endemic flora and fauna and absorb a substantial amount of the national carbon dioxide emissions for long sequestration in forest biomass and soil. They are also important components of the national hydrology as the origins of several major water sources. Long-term sustenance of these ecosystem functions of TRFs and TMFs depends on these forests maintaining their canopy structure, species diversity and biomass production, which are closely-linked to their underlying soil physico-chemical properties and soil carbon dynamics. Therefore, the primary objective of the present project will be to investigate and quantify the variation of soil physicochemical properties and soil carbon dynamics of TRFs and TMFs of Sri Lanka in a series of permanent sampling plots (PSPs) across an altitudinal gradient spanning from < 400 m to > 2000 m above sea level, which will span a substantial temperature gradient also. A companion project funded by the National Science Foundation will carry out detailed measurements of the above-ground forest canopy, vegetation structure, species composition and the associated processes in the same PSPs. Combined results of the two projects will enable identification of inter-relationships and controls between above- and belowground processes of TRFs and TMFs. More importantly, it will enable determination of how these two critically-important ecosystems will respond to long-term climate change, where increasing temperatures have been identified as the clearest signal.

Objectives

In order to seek solutions to the problems identified above, the present research is proposed with the following specific objectives:

1. To determine the variation of soil physical properties of tropical rainforests (TRFs) and tropical montane forests (TMFs) of Sri Lanka across an altitudinal gradient
2. To determine the variation of soil chemical properties, including essential plant nutrients, in the soils of TRFs and TMFs of Sri Lanka across an altitudinal gradient
3. To determine the mineralisation rate of soil organic matter and thus the amount of C-CO2 evolved annually in TRFs and TMFs of Sri Lanka across an altitudinal gradient
4. To determine the mechanisms of soil carbon stabilisation processes and thereby quantify the distribution of soil organic carbon (SOC) contents in different pools (e.g. unprotected, physically protected, chemically protected, and biochemically protected pools) in TRFs and TMFs of Sri Lanka across an altitudinal gradient
5. To determine the influence of soil properties and processes investigated under objectives 1, 2, 3 and 4 above in controlling the variation of vegetation traits (e.g. leaf nutrient contents and leaf physiological parameters), forest stand dynamics (e.g. species composition and turnover) and productivity (e.g. biomass production and carbon sequestration) in TRFs and TMFs of Sri Lanka across an altitudinal gradient

Major Equipment Facilitated by Grant

Reciprocal Shaker

Automated Water Station