Tree diversity and natural regeneration in Tropical Dry Deciduous Forest of Panna Tiger Reserve, India

The disturbance is a major factor driving the decline of tropical forests and their associated fauna. Henceforth, basic information on species diversity would be useful for assessing the success of management in the fragmented and human-disturbed landscape. We accounted for tree species diversity and their regeneration pattern from the tropical dry deciduous forest of Panna Tiger Reserve (PTR), India. Considering this, random vegetation sampling along with transects was carried out in different ranges of PTR. It is spread over in an area of 2998.98 km 2 that situated in the northern part of Madhya Pradesh and distributed in Panna and Chhatarpur district. The tropical dry deciduous forest inventory in the 10.6132-ha area yielded a total of 46 woody species of > 10 cm GBH, belonged to 23 Families and 40 genera. The regeneration represented 27 species of < 30 cm height (seedling) under 16 families and 24 genera while sapling, which ranges from > 30cm to 1.3m, showed 24 species of 13 families and 32 genera. The Shannon diversity of Trees, seedlings, and saplings was 2.684, 2.525, and 2.401 respectively. A total stand density and basal area of 2391 stems of trees were estimated as 225.285 stand ha − 1 and 90.016 m 2 ha − 1 respectively. Tectona grandis scored the highest IVI value of 59.44 (19.81% of total IVI for all species) among the dominated tree species, followed by Acacia catechu (24.94), Abrus precatorius (23.25), Zizyphus xylopyra (22.94), Anogeissus latifolia (22.16) and Lagerstroemia parviora (22.18). Nearly 23.913% of the total number of species was recorded as rare species. The highest seedling density was obtained for Diospyros melanoxylon followed by Zizyphus xylopyra, Aegle marmelos, Wrightia tintoria, and Tectona grandis, which declined in the subsequent sapling stage and showed a reverse pattern. Hence, the highest sapling density was recorded for Tectona grandis then Aegle marmelos, Wrightia tintoria, Diospyros melanoxylon, and Zizyphus xylopyra. A total of 36.956% of tree species were found to fail to establish in the community because species were represented by only adult or tree stage that listed as Not-regenerating. In terms of the most diverse family among the plant categories; viz. Tree, Seedling, Sapling, Fabaceae had the highest species richness. The highest tree stand density (127.576 stand ha − 1 ) was recorded in the girth class of 31-60cm (48.687% of the total tree stand density) followed by 10-30cm and 61-90cm. Likewise, a total basal area of 20.824 m 2 ha − 1 was occupied by 31-60cm that contributed 23.051% of the total basal area, so our data on the population structure of forest shows a similar trend wherein the distribution curve exponentially decreases with increasing girth classes that indicates not only a mid-successional forest but also a human-disturbed.


Introduction
Tropical forests are the most biologically rich and genetically diverse ecosystem on earth (Hubbell & Foster 1983) and cover roughly 44 percent of the global forest land area (Keenan et al.2015). Besides, these forests contribute for less than half of them as tropical dry forest (Murphy & Lugo 1986), and are considered to be most threatened and largely unprotected ecosystem than moist and wet tropical forest ecosystem (Lerdau et al. 1991;Laurance 1999;Trejo & Dirzo 2000;Li et al. 2006;Gerhardt 1993;Songer 2006;Janzen 1988;Olson & Dinerstein 2002;Miles et al. 2006). These forests are distributed in Central and South America; Africa; India; South-East Asia; and Australia (Gerhardt & Hytteborn 1992), and also have high phonological adaptation such as leaf trait so that tree species show leaf habits from evergreen to deciduous (Eamus 1999;Sandquist & Cordell 2007). According to Waeber et al. (2012), Tropical dry forest accounts for up to 60% of total forest extent in India, and Tropical dry deciduous forest occupies approximately 40.86% of total forest extent (ISFR 2019). Due to oral attributes, Rzedowski (1991) has used the term ecological island for the tropical dry deciduous forest that has originated by geographical isolation. This ecosystem is also designated as "Tall deciduous forest" (Ogawa et al. 1961) or "Mixed deciduous forest" (Royal Forest Department, 1962), and is found on the mainland of Southeast Asian countries, including Vietnam, Laos, Cambodia, Thailand, Burma, and India. This forest ecosystem is dominated by a large number of deciduous tree species, exclusively Teak (Tectona grandis) (Bunyavejchewin 1983).
Tree and forest of dry forest provide a wealth of environmental services and support the world's poorest people (Campbell 1996;Cunningham et al. 2008;Waeber et al. 2012). Henceforth, Tropical dry forest is vulnerable to anthropogenic disturbance; for example, conversion to agriculture, burning, extraction of valuable timber species, and unsustainable use of Non-timber forest product, which in turn re ect the forest fragmentation, degradation of forest land, and change in forest regeneration pattern (Rodger 1907;Lieberman & Li 1992;Menaut et al. 1995;Saha & Howe 2003). The mature primary deciduous forest is also being transformed into a degraded forest because of human-induced disturbance. For instance, the dry deciduous forest in India has been converted into dry deciduous scrub, dry savannah, and dry grasslands (Champion & Seth 1968;Singh & Singh 1989;Sagar & Singh 2004). According to Menon et al. (2010), It is estimated that 75% of the total forest cover comes under highly re-prone forest types such as moist deciduous, dry deciduous, and thorn forests of India.
The concept of quantitative inventories that provide information on the structural characteristics and species diversity within a particular forest ecosystem (Vankateswaran & Parthasarathy 2003) and its implication for conservation and management has been widely studied across the world. There is a vast amount of literature on structural characteristics of tree species and their regeneration in a tropical forest because tree species potentially lead to stability and complexity of forest ecosystem (Khan et al.1997;Rennolls et al. 2000;Rennolls & Laumonier 2000). They are also responsible for the development of other plant-dependent species (Whitemore 1990), such as herb layer by creating environmental heterogeneity in the lower forest layer (Bealty 2003;Gilliam 2007; Barbier et al. 2008).
In South-West China, The changes between the primary forest vegetation and the secondary plant communities in the Tropical forest of Xishuangbanna were studied by Zhang & Cao (1995), who also suggested local nature conservation. By using eld plots data with the combination of mapped environmental data and Landsat Thematic Mapper imagery, Ohman & Gregory (2002) were able to evaluate a method for predictive mapping of forest composition and structure that can probably be used for regional level planning not to local management. On the other hand, Banda et al.(2006) sampled tree species composition and their structural characteristics in four different levels of protection gradient from non-disturbed to highly disturbed area in the Miombo ecosystem of western Tanzania, and Duran et al. (2006) analyzed the variability of structure and tree diversity pattern at the landscape level of Mexican tropical deciduous forest. So did Tarrason et al. (2010) compare the structure, species richness, and diversity of the different types of tropical dry forest remnants in Nicaragua, Central America, and evaluated the new index viz, Social simpli ed Importance value Index (SsIVI) to assess the conservation status. Webb et al. (2011) studied the tree community structure and composition of Mixed Evergreen Deciduous tropical forest in Western Thailand and concluded that tree recruitment can be inhibited by the overgrowth of Bamboo cover. In favor of understanding the plant diversity in a Mixed Albies holophylla-Broad-leaved deciduous forest, Lee et al. (2012) assessed the spatial distribution pattern and association of dominant canopy tree species in Odaesan National Park, South Korea by using Ripley's K function. Marood et al. (2012) studied the vegetation structure and oristic composition along the edge of Montane forest and agricultural land to reforestation in the degraded forest landscape. Similarly, Phongoudome et al. (2012) determined the natural regeneration and tree species composition of primary and secondary forest of Tropical Mixed deciduous forest in Lao concerning manage secondary forest by natural or man-made restoration after logging and shifting cultivation. Usually, forests tend to have dynamic likely to be affected by both climatic and anthropogenic disturbance therefore Henri et al. (2013) addressed the reconstruction of the woody species regeneration in a semi-deciduous forest of Cota d'Ivoire. On the contrary, Apgaua et al. (2014) investigated the tree community structure of remained Seasonally dry tropical forests in the ecotonal area between the Cerrado and Caatinga, Brazil. Measuring the impact of selective logging, Djagbletey et al. (2018) assessed the oristic composition and carbon stock of tree species in logged and unlogged sites of the moist semi-deciduous forest in Ghana. In India, Rawat & Singh (1988), Parthasarathy & Karthikeyan (1997), Swamy et al. (2000), Panchal & Pandey (2004), Kar et al. (2012) and Subba et al.(2020) have investigated species diversity and structural characteristics of Oak forest in Central Himalaya, Tropical dry evergreen forest in South India, Humid tropical forest in Veerapuli and Kalamalai forest reserve, Semi-arid forest in Saurashtra region of Gujarat, Moist deciduous forest in Similipal Biosphere reserve, Moist Sal bearing tropical forest in Sumbuk reserve forest respectively. Additionally, India has also received attention along with the aspect of biophysical and Livelihood research. Sagar et al. (2003) studied tree species composition, dispersion, and diversity in response to disturbance gradient in a tropical dry forest, and reproductive and vegetative phenology of tropical tree at Kodayar in the Western Ghats was investigated by Sundarapandian et al. (2005). To provide information on the tremendous effect of anthropogenic re on juvenile trees, Saha & Howe (2006) surveyed the tropical dry deciduous forest of Central India. However, Singh & Kushwaha (2006) demonstrated variability in owering and fruiting phenology of tropical deciduous trees in Uttar Pradesh, India. In favor of producing high-quality seedlings, Singh & Raizada (2010) analyzed the impact of re and smoke on seed germination of tropical dry deciduous trees. Moreover, Quamar & Bera (2014) studied the pollen production and deposition behavior of Teak (Tectona grandis) and Sal (Shorea robusta) in the tropical deciduous forest of Madhya Pradesh, India. On the other hand, several studies have been conducted in the context of resource extraction that has adversely affected the vegetation structure and diversity of forest area. Accordingly, Purushothaman et al. (2000) accounted about 124 plant species that utilized by people living along the periphery of the forest area in Madhya Pradesh as used for fuelwood, fodder, and medicinal purpose and Narendran et al. (2001) was also evaluate the utilization and valuation of non-timber forest product from Nilgiri Biosphere Reserve, South India. In contrast, Arjunan et al. (2005) compared vegetation structure, diversity, basal area, and regeneration between sites with heavy human pressure and another site have no extraction or human pressure. Besides the negative effect of Non-timber forest product extraction on forest community, Mahapatra & Tiwari (2005) analyzed the importance of Non-timber forest products in the economic valuation of dry deciduous forest of India.

Study Area
Panna Tiger Reserve is a more sensitive habitat for Tiger and is located in Vindhya hill in northern Madhya Pradesh. In the year1981, the forest of the area was declared as Panna National Park following that included in the Project Tiger Reserve in the year 1994. It is situated in the Panna and Chattarpur district of Madhya Pradesh. It covers about 2998.98 km 2 out of which 792.53 km 2 including 191.35 Km 2 of the North forest division of Panna, is managed as the core area. It lies between coordinates 24°15'-24°20' latitude N and 80°00'-80°15' longitude E within Biogeographic province 6A "Deccan Peninsula-Central Highland" (Rodgers and Panwar, 1988) with an elevation range from 212 to 538 M.S.L. According to Champion and Seth (1968), the park has six forest types such as; Southern tropical dry deciduous teak forest, Northern tropical dry deciduous mixed forest, Dry deciduous scrub forest, Anogeissus pendula forest, Boswellia forest, and Dry Bamboo brakes. This forest is dominated by extensive plateau and gorges. The study area has four distinct seasons, hot summer from March to June, Monsoon (July to August), a short Post Monsoon from September to October, and Winter from Mid-November to February. The mean temperature range from − 0.7 o C in January to 47 o C in May (Sharma et al. 2007). The forest is characterized by the Ken river that has become a lifeline for reserve and also creates a waterfall on its way to the valley (FIGURE 1).

Data collection
Random sampling along the transect was carried out to assess the structural characteristics and species diversity of different tree species, seedlings, and saplings in the Tropical dry Deciduous forest of Panna Tiger Reserve. A total of 338 plots (covering a total area of 10.6132 ha) were sampled in different ranges during March 2019. The size of the plot varied from 10m radius for trees to 5m radius for seedling and sapling. In each plot, stems having > 10 cm GBH at 1.3 m height were considered as adult trees while stem up to the height of 30 cm was considered as seedling and > 30 cm height as a sapling.

Density
The density of the tree, seedling and sapling was estimated as "number of individuals/ ha" by following formula Density = number of individuals of the species / Area (ha) 3.2.2 Frequency frequency of a species was calculated by using following formula Frequency (%) = (Number of plots in which species occurred/ Total number of plots)*100

Basal area
The basal area of the tree was measured as girth of stem at breast height at 1.37m from the ground level (Curtis and McIntosh 1950) and calculated by using following formula.
Basal area = c 2 / 4π Where, C = Circumference at Breast Height

Important Value Index (IVI)
IVI is the sum of relative density, relative frequency and relative basal area of a species (Philips 1959). The relative density, relative frequency and relative basal area were estimated using following formula

Regeneration
The regeneration status of the forest was estimated based on the following categories: as per Shankar (2001) and Singh et al. (2017).

Equitability or Evenness
Evenness that range from zero to one was calculated by the following formula (Pielou 1966).

E = H/log s
Where, H = Shannon Index and s = the number of species.

Species richness
Species richness was calculated by the following formula (Margalef 1958 To observe tree species richness, a variety of non-parametric estimators were graphically plotted by using the software EstimateS version 9.1.0 (Colwell 2013). This program calculates sample-based rarefaction curves and their associated values by replicating a set of samples.
Chao1 is an abundance-based estimator and relies on rare species in the sample i.e. the number of singleton and the number of doubletons. However, Chao 2 requires only incidence-based data and depends on the number of unique and the number of duplicates.
The Jackknife is a technique for reducing the bias of estimates (Miller 1964). Thus, the rst-order Jackknife (Jack 1) estimate of species richness is based on the no of unique species and the number of samples, but second-order Jackknife (Jack 2) similar to Chao 2 that relies on the number of unique and duplicates and number of samples as well.
Bootstrap is based on a proportion of samples containing each species and requires only incidence data. On the other hand, the Abundance-based coverage estimator (ACE) and Incidence-based coverage estimator (ICE) are depended on sample coverage that requires a pattern of relative abundance of species in samples. Hence, ACE is based on those species which have < 10 individuals in the samples (Chao et al. 1993) while the corresponding Incidence-based coverage estimator likewise is based on species that found in < 10 sampling units (Lee and Chao 1994).

Extrapolation of sample-based rarefaction curve
To predict an asymptotic true species richness for a larger set of samples from the same assemblage, extrapolation of empirical sample-based rarefaction curve can be used which provides associated con dence interval as well.

Sample-based rarefaction curve
According to Chazdon et al. (1998)," observed species richness is a biased estimator of true richness for the assemblage sampled", so sample-based rarefaction curves were generated by plotting the cumulative number of tree species against the number of individuals censured in a 10.6132-ha area based on 100 randomizations of the sample order. Though, a total of 46 ± 1.93 species was recorded as observed species richness from the study area (FIGURE 2).
For reliable estimation of species richness, The comparison of the number of species recorded by different estimators was made using the same individual sampled, which resulted in a rarefaction curve was initially steep up to 546-1092 individuals followed by gradual species accumulation and attering till the 1638 individuals sampled.
In all estimators, more than 50% of the total species were recorded within 546-1092 individuals sampled in a 10.6132ha area. The second-order Jackknife (Jack 2) was best satis ed the estimation of species richness among the estimators as it reached a stable value of 54 after only 1092 individuals were sampled. While other estimator reached a stable value after 1638 individual sampled and yielded a low estimate of species richness than second-order Jackknife (Jack 2) (FIGURE 3) 4.2 Extrapolation of sample-based rarefaction curve FIGURE 4 shows the result for species richness extrapolation to two times the empirical number of plots for an empirical data set. A total of 49.34 ± 3.0 species were predicted for large sample size from the same data set that reached an asymptote after 600 plots.

Species richness, diversity and evenness
The tropical dry deciduous forest inventory in 10.6132-ha yielded a total of 46 woody species of > 10 cm GBH, belonged to 23 Families and 40 genera. The regeneration represented 27 species of < 30 cm height (seedling) under 16 families and 24 genera while sapling, which ranges from > 30cm to 1.3m, showed 24 species of 13 families and 32 genera (Table 1).

Species density, dominance and rarity (Singleton and Doubleton)
Analysis of species density, basal area, and IVI of different tree species (> 10 cm GBH and > 1.3m Height) area given in Species with one and two individuals are considered as singleton and doubleton or rare species. Nearly 23.913% of the total number of species was recorded as rare species. These were stabilized at the value of 7.35 + 1.97 for singleton and 4.03 + 1.79 for doubleton (FIGURE 2).
Overall, 19 tree species were considered as good regeneration because these species were able to establish in all three categories viz. tree, seedling, and sapling that contributed to 41.304% of total tree species. On the other hand, a total of 15.217% of tree species that were available in the tree and seedling stage considered as fair in status, but 36.956% of tree species was found to fail to establish in the community because species were represented by an only adult or tree stage that listed as Not-regenerating. Among the tree species, only four species viz. Holoptelea integrifolia, Stephegyne parvi ora, Feronia elephantum, and Gmelina arborea were accounted as poor regenerating, for these species could not be found in seedling rather possessed in tree and sapling stage only (Table 3).

Plant family
Taxonomic data on family-wise contribution to genera, species, and their density in different categories of plant community viz. Tree, seedling, sapling are summarized in Table 4.
In terms of the most diverse family among the plant categories, Fabaceae had the highest species richness. However, 14 families of trees, 12 families of seedlings, and 8 families of saplings consisted of single species. Comparing density on the family level, the highest density for tree, seedling, and sapling was found in Sapindaceae (25.104), Ebenaceae (16.206), and Apocynaceae (11.118) respectively.

Tree girth class-wise density distribution and Basal area
An analysis of tree girth class-wise distribution of tree showed that tree stand and basal area were consistently decreased with increasing girth class of tree stand. The highest tree stand density (127.576 stand ha − 1 ) was recorded in the girth class of 31-60cm (48.687% of the total tree stand density) followed by 10-30cm and 61-90cm. Likewise, a total basal area of 20.824 m2ha-1 was occupied by 31-60cm that contributed 23.051% of the total basal area (Table 5).

Discussion
In the year 1994, Panna National Park was renowned as the 22nd Tiger Reserve under the project Tiger to protect large carnivores mainly Tiger. For conserving Tiger, it is necessarily protect to all biodiversity including plants. The main objective of our investigation was to quantify habitat characteristics in terms of species composition and diversity in different categories of plant community such as tree, seedling, and sapling for Tropical Dry Deciduous Forest. According to Myo et al. (2016), the density, composition, and distribution of seedlings and saplings can serve as a robust indicator of forest structure.
The structural and oristic composition of the tropical dry forest is less complex than the wet forest, having about half and less number of tree species than those of wet forest (Murphy & Lugo 1986). Indices for species richness, abundance, dominance, and frequency are an e cient way for describing the structural and oristic composition of the vegetation (Lamprecht 1989).

Comparision for Sample-based rarefaction curve
The estimation of species richness is mainly in uenced by the spatial distribution of species (Palmer & White 1994). In favor of nonparametric estimation for species richness, Chao1 and ACE yielded the lowest species richness with an SD value of 48.05 ± 2.91 and 49.37 ± 1.32 respectively. These estimators are highly sensitive to non-random distribution. However, Chao2 and ICE performed similarly to each other, estimating its richness of 50.13 ± 4.9 and 51.59 ± 1.53 respectively. As these estimators are least sensitive to non-random distribution. The higher value for tree species richness is indicated by the Jackknife (Jack) estimator. Since rst-order jackknife (Jack 1) is based on the number of unique species and Second-order Jackknife (Jack 2) is based on the number of unique, number of duplicates, and the number of quadrate sampled (Chazdon et al. 1998). Moreover, in non-random distribution, the unique and duplicate can be distinguishable from singleton and doubleton respectively (Chazdon et al. 1998). For a similar reason, Secondorder Jackknife (Jack2) could estimate the highest number of species from an empirical data set.

Comparision for Diversity Indices
To compare species richness from other sites, a total of 46 tree species were enumerated as observed species richness on a 10.6132ha area. This value is higher than the values reported from other tropical dry deciduous forest (TDDF) in the country such as in Western Ghats of Tamil Nadu (22; Sundarapandian et al. 2005) Dutta and Devi 2017). This study coincides with the statement that given by Holdrige (1967) who commented the species diversity doubles from dry to the moist forest and triple from dry to wet forest. Consequently, the species richness in the present study was lower than many tropical moist and wet forests.
The general trend is that tropical forests attain the highest values of the Shannon Index (Knight 1975) and ranged from 0.83 to 4.0 in Indian Forest (Singh et al. 1984). During the study, the Shannon Diversity indices for the tree was enumerated with the value of 2.684 which is lower than reported by others in TDDF like 2. In the present study, the lowest value of dominance (0.108) than Simpson (0.891) and Shannon (2.684) is indicated its higher number of dominant species. This has been reported by Bajpai et al.(2020)

Comparision for stand density, basal area and rarity
The tree density of TDDF in our study area when compared with densities of the same forest type at other sites, revealed that PTR does not hold reliable estimates of tree density. For tree density in TDDF varies from 262.27 to 947 individuals ha-1 for trees of > 10cm GBH (Bunyavejchewin 1983;Gonzaliz-Rivaz et al. 2006;Banda et al. 2006;Sahu et al.. 2012;Bargali et al. 2014;Apgaua et al. 2014 andKothandaraman &Sundarapandian 2017). Although the tree density of 208.325 individuals ha-1 was obtained for GBH > 30cm, yet the tree density is not well within the range from 220 to 1520 that reported for other TDDF (Sagar & Singh 2005;Reddy et al. 2007, Pitchairamu et al. 2008Jhariya et al. 2012;Bargali et al 2014).
Though our estimates for the basal area (90.016 m2ha-1) seems higher than the previous study in Tropical Dry Forest (TDF) for > 10cm GBH that ranges from 0.6 in Similipal Biosphere Reserve, Odhisa (Reddy et al. 2007) to 64.2 m 2 ha − 1 in Veerapuli and Kalamalai Forest Reserve in the Western Ghats (Swamy et al. 2000).
According to Hett & Loucks (1976) and Denslow (1995), the disturbance impact can be determined within any forest ecosystem by using a girth-class distribution pattern. One study from India studied disturbance level and found that the intermediate size class (60-210cm GHB) attain a lesser degree of tree density and basal area, particularly in the moderate disturbed site because of selective logging of trees for a household purpose (Muthuramkumar et al. 2006). Additionally, these classes are also used for determining the forest age viz. Growing, medium, and climax or mature. The pattern discussed in the result section is manifested that forest structure can be considered as in mid-successional stage but also a human-disturbed. Other studies too have found the forest in the early and intermediate stage to show a higher density of stem with low basal values in contrast as the forest grows toward climax accordingly stem density decreases with high basal values (Yodzis 1986;Begon et al. 2006) In our dry deciduous forest, rare species (representing < 2 individual) contributed to 23.916%, which is lower than reported for TDDF (18-30% for single individuals; Sagar et al. 2003, 62.71-72 Swamy et al. 2000) in contrast the recorded value is higher than that reported for TDDF of Eastern Ghats., India (0.760% for < 2 Individuals; Panda et al. 2013). In terms of higher density and basal area, the general trend is the predominance of lower girth plant in lower class-size, decreases with increasing girth class. A similar pattern has been widely obtained for various Tropical Dry Deciduous forest in India (Reddy et al. 2007;Pitchairamu et al. 2008;Kar et al. 2009;Panda et al. 2013), in Tropical moist deciduous forest (Dutta & Devi 2013;Sahoo et al. 2017) and Tropical rain forest (Muthuramkumar et al. 2006) as well.

Comparision for plant families
The enumerated tree taxa diversity such as genera and species was contributed by 23 plant families which show the closer contribution of families in other TDF of North-East India (Sagar et al. 2003), South and South-West India (Mani & Parthasarathy 2006;Prakash et al. 2008;Gandhi & Sundarapandian 2014), Western India Pilania et al. 2015), Moreover, In terms of the number of species and genera, Fabaceae was found to be the most diverse family then followed by Combretaceae. Likewise, Fabaceae is the most dominated family in Tropical Dry Forest of several Neotropical countries; including Central America (Gonzalez-Rivas et al. 2006;Hilje et al. 2015), and North-South and South America (Ruiz et al. 2005;Duran et al. 2006;Apgaua et al 2015), in North-Western Ethiopia (Wale et al. 2012), Southern andCentral India (Ramanujan &Kodamban 2001;Fayiah et al. 2018) as well. Combretaceae is relatively abundant in the region of Udaipur district, Rajasthan  while Sapindaceae in Australia (Gillespie & Jaffre 2003), Lauraceae in South-East Asia (Webb et al. 2011), Rubiaceae in Eastern India (Reddy et al. 2007;Kar et al. 2009), Mimosaceae and Caparaceae in Southern and Western India (Parthasarathy & Karthikeyan 1997;Gandhi & Sundrapandian 2014;Pilania et al. 2015).

Comparision for Seedling and Sapling
The microenvironment likely regulates tree saplings or sprouts which in turn re ect the tree density in the forest (Khan et al. 1986).
The density of seedling in the PTR is lower than previous studies within other TDDF, Include a density of 10960-13680 seedling ha-1 in Bhoramdeo Wildlife Sanctuary  Similar to seedling density, the density of saplings is also found to be lower than other deciduous forests where values vary from 490 Sapling ha-1( Bargali et al. 2014) to 2476 Sapling ha-1 (Phongoudome et al. 2012). In the preceding year with a short rainy season, water availability may be insu cient for storing the required resources to produce owers which in turn re ect the seed production during summer.
The pattern of individual species densities in all three categories viz. Tree, seedling, and sapling mentioned in the previous section cumulatively result in the pattern of regeneration status of tree species (Table 3). Among the top ve seedling tree species, the highest seedling density was obtained for Diospyros melanoxylon followed by Zizyphus xylopyra, Aegle marmelos, Wrightia tintoria, and Tectona grandis, which declined in the subsequent sapling stage and showed a reverse pattern. This pronounced change may be a consequence of herbivory which has been reported in other studies in the Tropical dry forest (Vermeulen 1996;Cumming et al. 1997).
The highest sapling density was recorded for Tectona grandis then Aegle marmelos, Wrightia tintoria, Diospyros melanoxylon, and Zizyphus xylopyra. McLaren & McDonald (2003) stated that seedling germination, survival, and their size are directly in uenced by shading and soil water availability. As the season grows from wet to dry, a high light level will signi cantly decrease seedling survival (Gerhardt 1996;McLaren & McDonald 2003). Since Tectona grandis shows its a nity towards re because re can stimulate germination and establishment (Champion & Seth 1968;Khurana & Singh 2001) Similarly, It has been reported that re can also enhance germination in other deciduous species like Acacia catechu, Bauhinia spp. (Singh & Raizada 2010).
Lagerstroemia parvi ora, Acacia catechu, and Zyziphus xylopyra were co-dominant tree species and displaying a wide range of tolerance to biotic pressure and ecological amplitude as per Sagar et al. (2003). In 1999, thirteen villages were excited within the core area of PTR (Chundawat 1999 1994). For this reason, the occurrence of light-demanding species of Lagerstroemia parvi ora and Butea monosperma (Fayiah et al. 2018) was predominantly recorded from less distant areas to the forest edge. Despite, the forest has several commercially important tree species that harvest for livelihood purpose by local communities living around forest area for instance during May and June Diospyros melanoxylon leaves collection, fruits of Euginea jambolana, Ficus spp, Terminalia bellirica, and ower of Bassia latifolia, therefore, it might decrease the regeneration of these target species which ultimately reduces the forest cover and biodiversity (Garrigus 1999;Silori & Mishra 2001;Pouchepadaes & Puyravaud 2002) Of the top ve dominating species of seedling and sapling, Aegle marmelos and Wrightia tintoria could not establish themselves as dominating adult tree species. In our study area, leaf senescence started from the cool dry season that reached to peak in February and March. A study by Singh & Singh (1992) also revealed the initiation of leaf-senescence from a low-temperature dry period. Rainfall, temperature, light, and relative humidity are some of the factors that pronounce leaf phenology in the dry deciduous forest (Singh & Singh 1992;Brochert 1994;Van Schaik et al. 1993;Wright & Van Schaik 1994). This may signi cantly alter the pattern of seed germination, survival, and seed growth (Khurana & Singh 2000) Some species like Buchanania lanzan, Phyllanthus emblica, Allangium salvifolium, Terminalia arjuna, Bassia latifolia, Terminalia tomentosa, and Bombex ceiba are being characterized by adult or tree and seedling stage. Tectona grandis was estimated to be the highest dominated species and its canopy determines the germination, survival, and growth of other seedling species (Faiyah et al. 2018). Usually, canopy openness (Jennings et al. 1999), quality of light (Leakey et al. 2003) and soil moisture (Khurana & Singh 2000) favor the gain and loss under planted seedling (Tuomela et al. 1996;Pena-Carlas et al. 2002;Romell et al. 2008). Also, seedling tness is in uenced by natural or anthropogenic disturbance and biological traits of species, for example, If a su cient amount of soil moisture does not avail for germination, then Diospyros melanoxylon will germinate in the next season because it has the ability to extending its germination until the second wet season (Ghosh et al. 1976;Khurana & Singh 2001). Likewise, could not well thrive in the seedling stage, Lagerstroemia parvi ora was found to be the second co-dominant species. Because of seed polymorphism, Lagerstroemia parvi ora tends to produce a variety of seeds within the same individuals that can germinate in a wide range of environmental conditions (Shukla & Ramakrishnan 1981) Although not regenerating viz. no seedling and sapling, Boswellia serrata, Sterculia urens, Adina cordifolia, Terminalia bellirica, and Pterocarpus marsupium need consideration. As Dalling et al.1998 stated that a species can locally extinct in near future, not being accounted for in the seedling nor sapling stage. Boswellia serrata and Terminalia bellirica, being economically important tree species, showed low density. It might be caused by extracting for fruit and medicinal purpose respectively. Pilania et al. (2015) studied the phytosociological and ethnobotanical importance of tropical dry deciduous tree species in Western India who found these species are being exploited for fruits, medicinal and religious purposes.

Conclusion
In the present study, most of the area of Tiger Reserve is characterized by interspersed tall grasses between canopy trees across the two-season viz. Summer and winter may reduce seedling tness (Perera 2005). Whereas, some areas are badly infested by an invasive shrub species Lantana Camera so that this species may promote disturbance by changing resource availability (Vivrette & Muller 1977;Vitousek & Walker 1989;Boswell & Espie 1998).
Our result indicates that the density of large tree species is not only being replaced by small woody species which have relatively low propagules availability for regeneration (Maza-Villalobos 2011) like Acacia catechu, Lagerstroemia parvi ora, and Zizyphus xylopyra, but also the extrapolated species richness that was estimated by increasing the sample size, are not showing signi cant difference than occurred from empirical data set. The population structure also exponentially decreased due to illegal extraction of woody species, particularly those > 60 cm GBH and above (FIGURE 5). The data suggest that the forested area might gradually be converted into degraded savanna grassland in the upcoming year.

Declaration of interests
The authors declare that they have no known competing nancial interests or personal relationships that could have appeared to in uence the work reported in this paper.

Figure 1
STUDY AREA MAP. Note: The designations employed and the presentation of the material on this map do not imply the expression of any opinion whatsoever on the part of Research Square concerning the legal status of any country, territory, city or area o bbnhjr of its authorities, or concerning the delimitation of its frontiers or boundaries. This map has been provided by the authors.