Floristic assessment of semi evergreen forests of a peripheral site in Hadagarh Sanctuary, Odisha, India

Phytosociological study was carried out in the outer periphery region of Hadagarh Wildlife Sanctuary, Odisha, India. An attempt has been made to find out the characteristics of the vegetation community of the forests of the sanctuary. Analysis of the vegetation was done following the standard ecological methods widely adopted for such studies (quadrat method). A total of 68 plant species from 30 families were documented comprising of 14 species of tree, 42 species of shrubs and saplings and 12 species of herbs and seedlings. This study provides a baseline data for all such future studies as no previous ecological assessment about the forest vegetation of the sanctuary is available. In terms of Importance Value Index (IVI), Azadirachta indica with IVI value of 61.45 among trees was found most dominant followed by Shroea robusta (46) and Schleichera oleosa (37). Similarly most common plant species amongst shrubs and herbs were Ageratum conyzoides L. (IVI-40.08) and Mimosa pudica L. (IVI-45.67). The sanctuary has been under various anthropogenic pressures resulting in depletion of the vegetation. Near absence of saplings and seedlings of dominant forest trees is a matter of concern in the peripheral region of the sanctuary. The study revealed that, a suitable long term management intervention to step up regeneration of population in this area will go a long way in improving overall ecological and aesthetic value of the forests of the sanctuary area.


INTRODUCTION
The concept of Sustainable development has received worldwide acceptance. Sustainable planning of ecologically important regions could not be taken up due to lack of sufficient data on structure and functioning of ecosystem. Hadagarh Wildlife Sanctuary is one such area containing diverse floral and wildlife composition but does not have much information about its phytosociological composition. The floristic composition and phytosociological attributes are useful for comparing one community with the other from season to season and from year to year under certain environmental stress factors (Singh and Weigand, 1994). Large number of animals and plants inhabit the earth in a variety of habitats and ecosystems (Wilson, 1992). Odisha is one of the richest biodiversity regions in Southeast Asia. Saxena and Brahmam (1996)  There is such a vast repositories of animals and plants found across the planet with a distinct biological corelationship maintained and sustained by various adaptations vis a vis changing environment, inter dependence among the different life forms, sustained productivity and food chain/web relationships, nutrient cycling and energy flow etc. Phytosociology reveals the organization and structure of plant diversity which helps in determination of the distribution pattern of individuals among the species in a particular habitat therefore such analysis is important for understanding the functioning of any community (Warger and Morrel, 1976). Phytosociological status of Kuldiha Wildlife Sanctuary Odisha, India reveals that there is a big gap between the values of various structural parameters and tree species having very low values of IVI deserve more attention (Rout et al, 2018 (Mishra et al, 2008). Presence of high species richness and diversity, mean stand density and species rarity indicates the uniqueness and potentiality of SBR for conservation of ecosystem in its totality . Forests in the peninsular India are decreasing at a fast rate, though the data on structure and functional dynamics of these forests (Parthasarathy and Sethi, 1997) are scarce. A few studies in Eastern Ghats of Tamil Nadu (Kadavul and Parthasarathy, 1999a, b;Chittiibabu and Parthasarathy, 2000;Natarajan et al., 2004) have been conducted reflecting the floristic composition of forests in the area. More studies in tropical forests are (Tripathi and Singh 2009;Hegde et al., 2011, Bajpai et al., 2012Dangwal et al., 2012;Sahu et al., 2012;Verma et al., 2013;Sangma and Lyngdoh, 2014;Ahmed and Sharma 2014;Pradhan and Rahman, 2015;Knight, 2015;Sundarapandian and Subbiah 2015;Shahid and Joshi, 2016;Bajpai et al., 2017;Masens et al., 2017;Shiferaw et al., 2018). Sahu et al. (2010a) and Bhadra and Pattanayak (2016, 2019 have also studied tree Species Population Dynamics in the Tropical Dry Deciduous Forest of Gandhamardan Hills, Eastern Ghats, Western Odisha. Behura et al. (2016) highlighted the ecological significance of native species which are effective ecological tools towards conserving the biodiversity and enhancing the ecological services in a restored habitat. From various studies, it is seen that phytosociological characteristics of Western Ghats have been carried out over a period of time on the forest vegetation of the area whereas a few data are available about the forests of Eastern Ghats, particularly about Odisha. The phytosociological studies conducted in other parts of Odisha are by Sahu et al. (2007), Ekka andBehera, (2011), Behura et al. (2015) and Nayak et al. (2016) etc. Odisha accounts for about 45% of the forest area in the Eastern Ghats. Therefore, the present study was aimed at documenting the status of the present vegetation structure of Hadagarh Wildlife Sanctuary through a detailed phytosociological analysis of the forest ecosystem involving parameters like relative density, abundance, relative frequency, relative basal area and Important Value Index, which will be helpful to plan for a better management intervention to enhance the quality of forest ecosystem.

Study area
The Hadagarh Wildlife Sanctuary spreads across the districts of Keonjhar and Mayurbhanj in the state of Odisha, covering an area of 191.06 Sq Kms (Longitude 86°10' to 86°22' E Latitude 21°23' to 21° 12 'N) which was notified vide Government notification dated 06.12.1978 ( Figure 1) (Odisha Wildlife Organization, 2020. www. wildlife. odisha. gov.in). This area, therefore came under the status of a 'protected area' under the provisions of the Government from the date of its notification.
It lies in the catchment of Salandi River, one of the major tributaries of river Baitarani and is close to the Hadgarh Reservoir of Salandi dam. This region is rich in mixed deciduous forests and provides ideal habitat to variety of wildlife. The Baula area of sanctuary consists of two hills on either sides of the river and spreads across Satkosia RF of Mayurbhanj and Baula RF of Keonjhar district. The valley comprises of Hadagarh reservoir and its catchments. There are 16 villages, largely dependent on the ecological resources of the sanctuary. The demography of the area reveals dominance of backward classes and tribes like Santhals and Hos. Their regular day to day needs like firewood, grazing of domestic animals, timbers, medicinal plants etc are fulfilled from the resources available within the forests. Villagers' residing near the boundary allow cattle into the sanctuary, which is a common feature in the area. The relative humidity generally remains above 60%, maximum temperature 35°C during April-May and 6 degree Celsius during November -January of the year. Average rainfall ranges from 1718 mm to 2369 mm with 86 rainy days in a year. Cyclone with wind is frequently observed during September to

Vegetation study
The sampling of vegetation was done for trees and shrubs only once for one year during summer (March -May) and for herbaceous vegetation and seedlings three times in a year i.e. for summer (March-May), winter (December-January) and rainy season (July-September). Similar observation continued for the 2nd year also. The data thus obtained were used for analysis of all structural vegetation parameters for phytosociological analysis.
Random sampling plots were identified for the study. The quadrat size was taken 10 x 10 m for trees, 5 x 5 m for shrubs and 1 × 1 m for herbs and seedlings. All the plants were classified into following three categories taking into account their girth class i.e. circumference at breast height (cbh) (i) Herbs and Seedlings (0-10 cm cbh) (ii) Shrubs and Saplings (10-30 cm cbh) and(iii)Treesmore than 30 cm cbh and a total of 20 quadrats were sampled for each strata of vegetation. The size and number of quadrats, collection of data from the quadrats were based on standard ecological methods of Misra (1968) and Kershaw (1973). Analysis was done for arriving at phyto-sociological parameters following the Philips (1959) and Curtis (1959) to compute density, basal area (BA), frequency, relative density (RD), abundance, relative frequency (RF), relative basal area (RBA) and Important Value Index (IVI).IVI was determined as the sum of the relative frequency, relative density and relative dominance for tree layer. The following formulae were used for calculation:  Brahmam,1994-1996), Botany of Bihar and Orissa (Haines,1921(Haines, -1925 and herbarium of Botany department, Utkal University, Bhubaneswar, India.

RESULTS AND DISCUSSION
Analysis of vegetation reveals that 68 plant species from 30 families were available in the area with 14 species of tree, 42 species of shrubs and saplings and 12 species of herbs and seedlings (Tables 1 to 3). The species of trees, shrubs and saplings and herbs and seedlings belonged to 13, 29 and 9 families respectively. Importance value Index (IVI) is the measurement of ecological amplitude of species (Ludwig and Reynolds, 1988) which indicates one of the ability of a species to establish over an array of habitats. It gives composite information by taking into account the relative density, relative frequency and relative basal area. The frequency, abundance and density values are suitable for herbs and shrubs (Airi et al., 2000). IVI is an important information for all species. The vegetation characteristics of the area should be looked into through upperstory, middle-story and under-story vegetation for the purpose of a holistic assessment. The high importance value index of the species states its dominance and ecological success, its better power of regeneration and ecological amplitude in the area (Bhandari et al., 1999). The dominant tree species having maximum RD and RF values were Azadirachta indica followed by Shorea robusta and Lannea corromandelica ( Table 1).The IVI of A. indica was highest followed by S. robusta, Naringi crenulata, Tamarindus indica and Schleichera oleosa. Mishra et al., (2012) Shorea robusta was found as the dominant species in the SBR having IVI of 77.67 followed  by Terminalia alata (16.13) and Anogeissus latifolia (13.43). Wendlandia sp. had IVI of 0.25 and was considered as the rare species of the reserve. All other tree species showed intermediate range of IVI Among the shrubs and saplings which occupy the middle storey vegetation Ageratum conyzoides exhibited highest IVI followed by Combretum roxburghii, Holarrhena antidysenterica and Combretum decandrum ( Table 2).
The middle storey vegetation comprised of a good numbers of woody climbers and liana like Combretum roxburghii, Smilax macrophylla, Cissampelos pareira, Ichnocarpus frutescens. Similarly, analysis of herbs and seedlings (understory vegetation) (revealed Cynodon dactylon having the highest IVI followed by Arundo donax, Mimosa pudica and Sida rhombifolia. The plant species observed and encountered in the study belonged to 30 different families with most of the species belonging to Mimosaceae followed by Ebenaceae, Acanthaceae, Asteraceae, Combretaceae etc. It is important to note that majority of the families were represented by only two or less number of species. Though vegetation can be described in terms of a number of parameters including frequency, density and cover the use of any one of these quantitative parameters could lead to over-simplification or under-estimation of the status of the species (Kigomo et al., 1990;Oyun et al., 2009). Low ecological status of most of the tree species in the present investigation as evidenced by the IVIs, may be attributed to lack of dominance by any one of these species, suggesting positive interactions among the tree species . In addition to the above findings, several cutting stumps were also observed indicating impact of anthropogenic activities in one of the forest vegetation in the area. Plant species like Shorea robusta, Cassia fistula have local economic importance. Similarly, plant species like Diospyros ebenum, Acacia nilotica. Azadirachta indica, Strychnos nux-vomica, Andrographis paniculata, Alangium salvifolium , Holarrhena antidysenterica, Smilax macrophylla, Asoaragus racemosus., Xantolis tomentosa etc have been used by the local population for years for preparation of medicines. Similar use of such plant species by people have been reported by various studies in India and abroad (Brahmam and Saxena, 1990;Girach, 1992;Sahoo and Mudgal, 1995;Mohanty et al., 1996;Brahmam et al., 1996;Aminnudin and n, 1996;Mehra et al., 2014;Bajpai et al., 2016;Rout et al., 2018). These plant species need urgent attention from the conservation point of view as their numbers are decreasing owing to factors like unsystematic and uncontrolled harvesting, grazing pressure from domestic animals and many other anthropogenic pressures (WP, 2008(WP, , 2017. The population residing inside and adjoining area of the sanctuary have been dependent on the resources of this forest ecosystem which will have long term implications. This may be fairly attributed towards their lack of awareness on the issues concerning ecosystem services. Extensive use of natural vegetation in the sanctuary in the past has led to decrease in the provisioning services and increasing human demands has been the major case of deterioration in the condition of the natural habitats and increasing rarity of plant biodiversity (Giam et al 2010). The middle and lower storey vegetation showed presence of many saplings and seedlings of tree species like Morinda tinctoria, Cassia siamea, Holarrhena antidysenterica, Azadirachta indica, Cesearia elliptica, Acacia nilotica, Diospyros ebenum. These plant species need proper protection to grow as big trees. These plants are facing fierce competition in the ecosystem for space and sunlight due to threat from demands, weed species and other biotic impacts. As a result, there are a low percentage of old grown trees in the peripheral site.   These species have shown good regeneration pattern in some of the areas of the study. Therefore, it is important that anthropogenic activities in this area like overgrazing, encroachments, illegal felling etc need to be curtailed suitable intervention (WP, 2008(WP, , 2017. Despite having the status of a protected area of the country; the vegetation needs more attention from the habitat conservation point of view. The area needs management intervention for speedy regeneration of plant species. The phytosociological analysis reveals good generation potential of the habitat and the tree species having low IVIs , tree saplings and seedlings deserve due attention to ensure strict enforcement of the rules and better monitoring for enhancement of ecosystem stability of this protected area. For addressing forest management issues of the sanctuary, collection and analysis of long term ecological data by scientific baseline studies covering all structural parameters will be helpful to know the present state of ecological health of the ecosystem. Various forms of anthropogenic pressures have affected the habitat which include logging, illegal hunting, and other development challenges like mining in peripheral areas. The conservation efforts as per working (management) plan prescriptions have not so far yielded desired result. Therefore, for a sustainable ecosystem and community management and for reducing biotic pressure, the management methodology also needs to be modified for developing a Long Term Research Network to ensure improvement in. structure and function of ecosystem.