Introduction

Monitoring of biodiversity and particularly tree diversity & dynamism is becoming important recently due to its emerging economic value, especially in the global biodiversity hotspots such as the Western Ghats. It is important for tropical countries to make better assessments of carbon sequestered in their forests and charge developed, carbon-emitting temperate countries accordingly. India can lead the developing countries in this debate, using its monitoring data from the network of over hundred preservation plots across the country. These plots measure about a hectare each and the forest department has been re-enumerating the girth of trees therein every five years.

Evergreen forests are important in this context as they possess highest biomass amongst tropical forests. Fairly detailed analysis on dynamism i.e. growth, mortality & recruitment is available for the evergreen forest of the southern Western Ghats due to the publications by the Forest Officials and the French Institute, Pondicherry. There have been hardly any publications about dynamics of northern forests. Also, only a few preseravtion plots have been monitored at Bhimashankar & Mahabaleshwar during the last few decades. Further, these plots exist only in dwarf, secondary forest on the plateaues. Thus, RANWA established few small plots totalling 0.5 ha each in the tall, climax evergreen forests on slopes of Bhimashankar & Koyna during 1994-5, with the guidance of Maharashtra State Forest Department (MSFD). Later, MSFD established during 1995-6 monitoring plots measuring 5 ha at Bhimashankar, Koyna with stones cairns & metal plates. The RANWA, which are identified with the paint on the border trees & maps on paper, have been re-enumerated during 2001, providing a first picture of their dynamism based trees with DBH>10 cm i.e. GBH> 30 cm.

Location

The two Bhimashankar plots, located at 800 m a.s.l. measure 50x50 m i.e. 0.25 ha each. The riparian one is located 500 m before the Vinayaka Temple between the footpath & the Bhima stream, 25 m to the left side i.e. east of the footpath. Remarkably, this plot hosts huge trees of Cinnamomum zeylanicum (CZ). The non-riparian one is located on the slope 200 m to the south of the Vinayaka temple. Significantly, it harbours huge trees of Cassine paniculata (CP).

In Koyna, the plots are situated at 700 m a.s.l. in the `Redetodiche Ran' on the north facing slopes to the north-west of Zadoli village. The riparian plot, located just beneath the waterfall comprises of two 50x25 m (0.25 ha) sub-plots, one along the eastern bank (identified after huge trees of Chrysophyllum lanceolatum- CL) & another along the western bank (identified after huge tree of Ficus nervosa- FN). The non-riparian plot measuring 50x50 m (0.25 ha) is situated 100 m to the west of the stream, identified with two huge Persea macrantha (PM) trees.

Species Composition

The riparian plot in Bhimashankar contains only 55 trees belonging to 19 species while the non-riparian plot contains 75 trees belonging to just 11 species. Together, these Bhimashankar plots totaling 0.5 ha contain 130 trees belonging to 20 species. The riparian plot at Koyna contains 126 trees belonging to 19 species while the non-riparian plot contains 112 tres belonging to 20 species. Together, these Koyna plots contain 238 trees belonging to 16 species. Altogether, Bhimashankar & Koyna plots totaling to 1 ha contain 368 trees belonging to 31 species.

Important species at Bhimashankar include Dimorphocalyx lawanus (25%), Mangifera indica (18%), Olea dioica (14%), Syzygium canarensis (7%); while at Koyna these include Dimocarpus longan (26%), Holigarna grahami (12%), Knema attenuata (11%), Syzygium canarensis (6%), Garcinia talboti and Turpinia malabarica (5% each).

Memecylon umbellatum, a pioneers species I represented only 2-4% in these climax, shady forests known to be dominant species in the hilltop evergreen forests of northern Western Ghats, such as at Mahabaleshwar, which are most probably secondary forests developed after shifting cultivation and on poor, lateritised soils.

Dynamism

These plots have gained & lost about 15-20 trees/ha, with annual mortality & recruitment rate of 0.3% p.a., which is much lower than the southern Western Ghats & the globe (1-2% p.a.). The trees appear to be growing at the rate of 1.1%/yr at Bhimashankar & 0.7%/yr at Koyna. Given that these forests have a biomass of 400 t/ha & 325 t/ha respectively, these may be adding about 4t/ha & 2.5t/ha annually. If half of this is carbon, as is generally believed, these forests may be sequestering carbon at about 1 to 2 t/yr. This is about two thirds of the estimates for evergreen forests in the southern Western Ghats and half the estimates worldwide.

Implications

While it is important to stress the need for protecting biodiversity and sequester carbon, it is equally important to assess efficacy of ongoing conservation measures. This concept may now become applicable to Medicinal Plant Conservation Areas (MPCAs) for accessing international carbon funding as incremental component. MSFD has established an MPCA measuring @ 500 ha at Koynanagar, in collaboration with NGOs Rural Communes & FRLHT. This note helps in estimating carbon sequestration to be about 500 t p.a. by this MPCA Funding may be justified towards maintaining these forest imposes an opportunity costs by not reverting to lucrative land uses. For, the carbon sequestered by the climax forest may be released through litterfall & treefall, and may not result in net sequestration on long term basis. Its is important for NGOs to appreciate the positive steps taken by the government, besides criticisising where needed, so as to guide the further developments, as this paper attempts.

Bibliography

Gokhale Y., Bhagwat S., Gour-Broome V., Utkarsh G. , Barve V., Joshi P. A., Sathe B. 1995. Biodiversity & Ecological Monitoring of highly seasonal tropical moist evergreen forests of Western Ghats, Maharashtra State, India., Proceed. of SIMAB conference on measuring & monitoring forest diversity: in international network of monitoring plots; Washington.

Ravindranathan N. H., Gadgil M., Somashekhara B. S. 1997: Carbon Flows in Indian Forests. In Climatic Changes, Kluwer Academic Publishers, pp. 297-320.