An assessment was carried out through random quadrates plot in the study area. A total 129 plant species were documented. Frequency and density varied greatly among the taxa, while many species were not evenly abundant in the study areas. The present study revealed that there are many medicinal plants which are used by local peoples, who residing near the forest area. Besides medicine, plant resources were found utilized as other sources as vegetables and also for forage, manure, sheltering and religious purposes which indicates diversity of the study area and needs urgent conservation.

Keywords: biodiversity, invasive species, medicinal plants, plant diversity

India is one of the 12 centres of mega-diversity in the world and encompass of 17,500 flowering plant species. It exhibits a wealth of complex and diverse ecosystems with a great deal of variation.¹ It accounts for 8% of the global biodiversity with only 2.4% of the total land area in the world.² Plants are one of the major component of biodiversity, thus the knowledge of plant species found in the different areas of the world is a pre-requisite to conserve the ecological biodiversity and an essential resource for human well-being.^3,4 For this reason precise information of the known local plant species from a given area is essential. It is worth to explore any area with wide range of forest types and identify the economically and medicinally important plant species found there. Further the knowledge about the plants in the region is essential with the increasing conspicuous of people about the environment and its impact on living organisms in general.

The study area Kusnur is located at 14. 69 42.41 N 75.23 00.89 E in the outskirts of Western Ghats lies in a maiden with a few outcrops of low hills. The topography of the area in not even, so it create many minor as well as major tanks. The soil pattern changes variably and annual rainfall is fairly good. The survey was carried out in 2009-2010. The sufficient sample plots of 30 x 30m were laid out randomly, covering the entire forest area about 339 acres. The trees were identified and the density and diameter of each tree species per plots were recorded^5‒7 and analyzed for carbon sequestration followed by Pearson et al.⁸ The collected specimens were identified with the aid of floras.^9‒12 The collected specimens were pressed and prepared herbarium followed by dry method of Jain and Rao.¹³ The specimens were deposited in the Herbarium of Botany Department, Karnataka Science College, Dharwad.

Floristic

The survey indicates that, they are about 129 species belonging to 109 genera under 52 families (Table 1). Of the 52 families documented, the family Fabaceae is the dominant family, comprising 9 spp., the dominance of Fabaceae may be due to the nitrogen-fixing bacteria with which these taxa often are associated, allowing these species to improve their soils.¹⁴ This was followed by Caesalpiniaceae (8 spp.), Euphorbiaceae (7 spp.), Capparaceae and Mimosaceae (6 spp. each), Asclepiadaceae, Asteraceae, Malvaceae, Tiliaceae are represented by 5 species each. The families Boraginaceae, Liliaceae, Rubiaceae are represented by 4 species each. Seven families are represented by 3 species each, they are: Acanthaceae, Apocyanaceae, Convolvulaceae, Moraceae, Poaceae, Rutaceae, Verbenaceae. Again seven families are represented by 2 species Amaranthaceae, Combretaceae, Dioscoreaceae, Meliaceae, Sapindaceae, Scrophulariaceae and Vitaceae. The family Aizoaceae, Alangiaceae, Anacardiaceae, Aponogetonaceae, Araceae, Aristolochiaceae, Cactaceae, Calestraceae, Cucurbitaceae, Diospyraceae, Flacourtiaceae, Hypoxidaceae, Lamiaceae, Lythraceae, Menispermaceae, Myrtaceae, Oleaceae, Polygonaceae, Rhamnaceae, Sapotaceae, Simaroubaceae, Solanaceae, Sterculiaceae, Urticaceae, Violaceae and Zingiberaceae are represented by only a single species.

Of these, many are medicinally important plants and other economic uses are beedi (Diospyros malabarica Kostel), plate (Butea monosperma (Lam.) Taub.) and broom making (Dodonea angustifolia L.f.) plants were also found in the area. The community managed forest area is over dominated by Eucalyptus globulus Labill. (Myrtaceae), Gliricidia sepium (Jacq.) Kunth ex Walp (Fabaceae) and Azadirachta indica A. Juss (Meliaceae). The survey clearly indicates that, there is a severe threat to the forest mainly from these two alien species i.e. Eucalyptus globulus Labill. and Gliricidia sepium (Jacq.) Kunth ex Wal. Seed dribbling programme was conducted every year since 1987. It was not been success, because these two invasive alien species (Eucalyptus globulus Labill. and Gliricidia sepium (Jacq.) Kunth ex Wal.) are over dominated and they emits oil through the leaves. It affects the germination and growth of the other species especially native species and this is known as allelopathic interaction.

Carbon sequestration observation during quadrate studies

The sufficient number of quadrats of 30x30meters size was laid randomly, covering the entire forest area. The obtained result is given below:

Number of Poles (Plants) per quadrate = 86

Girth of single Pole = 20cm

Height of single Pole = 5meter or ca. 15feet

Then the number of Eucalyptus standing (poles) in one acre = 12470/acre

12470 x 339 acre of community managed forest area = 42, 27,330 poles (Plants) with 20 cm girth and 5 meter height are available in Kusnur forest.

The outcome of the result indicate the approximate amount of carbon sequestration is 84,34,660kg {the process of capture and long-term storage of atmospheric carbon dioxide (CO2)}in Kusnur village alone.

The present study recorded 129 species of plants belonging to 109 genera and 52 families in the study site. Among total families, the family Fabaceae is the dominant family. 42, 27,330 poles (Plants) with 20cm girth and 5meter height are available in Kusnur forest. The process of removing carbon from the atmosphere and depositing in the plants it acts as a carbon reservoir in Kusnur village. The approximate amount of carbon sequestration is 84,34,660kg.

The study highlights a severe threat to the forest mainly by alien species. Hence the forest managers should pay attention to the natural composition of forest communities and should not try to replace the native species by invasive ones. Presently, there is a need for increased legal protection, well designed management practices to conserve the local diversity of the study area. Some indigenous species should be planted in the study area which will fulfill the demand of local people.

None.

Authors declare there is no conflict of interest in publishing the article.

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