Department of Environmental Studies, Cochin University of Science and Technology, Cochin 682022, INDIA.
During the study, about 479 species of flowering plants belonging to 335 genera under 103 families were recorded from all the forest types of the Tiger reserve. Out of the 479 species, 214 were tree species, 78 belonged to shrubs, 116 Herbs and 71 Climbers. While concerning the habitat of the species, 290 species were recorded from the West coast tropical evergreen forest, 196 species from Semi evergreen forest, 222 species from Moist deciduous forest, 64 species from Dry deciduous forest and 96 species from Teak plantation forest. Euphorbiaceae is the largest family which constitutes 23 species, followed by Lauraceae (18 species) and Meliaceae (14 species). Out of 479 arborescent species recorded, 107 species belongs to various Western Ghats endemics, which contribute about 23 per cent of the total species. 39 species are endemic to Western Ghats, 61 species are endemic to Southern Western Ghats, and 7 species are endemic to Southern Western Ghats of Kerala.
39 species of the reserve belongs to various threat categories. The RET species such as Agalaia barberi Gamble and A.lawii (Wight) Saldanha are found to be second and third dominant species of evergreen forest based on IVI values. Vateria indica L. a critically endangered species is found to be the fifth most dominant tree species of evergreen forest. This study indicates that quantitative studies are also essential to have a real status of plants on their distribution, which leads to formulate the conservation policies. Ophiorrhiza brunonis Wight & Arn. a possibly Extinct herb species also rediscovered its survival in the reserve. Identification of unique sites, locating the habitats of selected species with Global Positioning System (GPS), mapping of important Rare, Endangered and Threatened plants with their density status, etc., can be used for conservation purpose, especially for species like Ophiorrhiza brunonis, which was considered as possibly extinct and now relocated in the study area.
There were 24 number of epiphytic orchid species recorded, the common epiphytic orchid species were; Aerides ringens (Lindl.) C.E.C. Fisch, Oberonia sebastiana Shetty & Vivek., Bulbophyllum sterile (Lam.) Suresh, Oberonia santapaui Kapad., Vanda tessellata (Roxb.) Hook. ex D. Don, etc., 10 of epiphytic orchid species were shown the endemism towards the various parts of Western Ghats and Peninsular india. The common epiphytic pteridophytes recorded from the PKTR were Drynaria quercifolia (L.) J. Sm., Pteris quadriaurita Retz., Pteris longipes D. Don, Microsorum punctatum (L.) Copel., Asplenium nidus L.etc. Girth class distribution of entire PKTR was shown an inverted ‘J’ shaped curve. The distortions in the curves were seen in Teak plantation and Moist Deciduous forest types, due to over exploitation and selective logging in the past. Subsequently the forest department neglected Teak plantation and stopped the monoculture at PKTR, which paved the way for the invasion of indigenous flora taken its upper hand. As per the record, these are plantations, which are functionally acting as mixed moist deciduous patches. These patches will be attained the status of Moist teak bearing forest (3B/C1) under Champion and Seth forest type classification in near future.
The study has demonstrated the capacity of remote sensing and GIS in detecting the land-cover change with data from different sensors in spite of the absence of past ground data, with appreciable level of accuracy. For design of meaningful conservation strategies, comprehensive information on the distribution of species, as well as information on changes in distribution with time is required. It is nearly impossible to acquire such information purely on the basis of field assessment and monitoring. Remote sensing (RS) provides a systematic, synoptic view of earth cover at regular time intervals, and has been useful for this purpose (Nagendra, 2001). The integration of these tools can increase the accuracy of forest analysis at different spatial scale.
The results quantify the land cover change patterns in PKTR area and demonstrate the potential of multi temporal remote sensing data to provide an accurate, economical means to map and analyze changes in land cover over time that can be used as inputs to land management and policy decisions. The forest cover digital maps based on satellite remote sensing data and GIS techniques can supplement existing conventional ground based sources of information for monitoring changes in the forests cover on a regular basis, which can be helpful for forest resource management and future planning for the development of the areas.
The rarity of woody species and a greater number of singletons in the site underline the need to preserve the vast area of this forest. The establishment of plantations involves alternations of the rainforest habitat. Habitat alteration includes clear felling (for teak plantations) and removal of many large trees, climbers and under storey vegetation. Such a habitat change poses severe threats to wildlife. The PKTR, besides being a biologically important area with unique flora and fauna, is also a habitat for wildlife. It is also a catchment area for 8 river systems. Hence, the protection of this reserve is crucial for the biological conservation of species and human welfare.