Koushik Majumdar

Tree species diversity and stand structure along major community types in lowland primary and secondary moist deciduous forests in Tripura, Northeast India

Tree species diversity and population structure at different community types were described and analyzed for primary and secondary lowland moist deciduous forests in Tripura. Overall 10,957 individual trees belonging to 46 family, 103 genera and 144 species were counted at ≥30 cm DBH (diameter at breast height) using 28 permanent belt transects with a size of 1 ha (10 m × 1000 m). Four different tree communities were identified. The primary forests was dominated by Shorea robusta (mean density 464.77 trees·ha−1, 105 species) and Schima wallichii (336.25 trees·ha−1, 82 species), while the secondary forests was dominated by Tectona grandis (333.88 trees·ha−1, 105 species) and Hevea brasiliensis (299.67 trees·ha−1, 82 species). Overall mean basal area in this study was 18.01m2·ha−1; the maximum value was recorded in primary Shorea forest (26.21 m2·ha−1). Mean density and diversity indices were differed significantly within four different communities. No significant differences were observed in number of species, genera, family and tree basal cover area. Significant relationships were found between the species richness and different tree population groups across the communities. Results revealed that species diversity and density were increased in those forests due to past disturbances which resulted in slow accumulation of native oligarchic small tree species. Seventeen species were recorded with <2 individuals of which Saraca asoka (Roxb.) de Wilde and Entada phaseoloides (L.) Merr. etc. extensively used in local ethno-medicinal formulations. The present S. robusta Gaertn dominated forest was recorded richer (105 species) than other reported studies. Moraceae was found more speciose family instead of Papilionaceae and Euphorbiaceae than other Indian moist deciduous forests. Seasonal phenological gap in such moist deciduous forests influenced the population of Trachypithecus pileatus and capped langur. The analysis of FIV suggested a slow trend of shifting the population of Lamiaceae group by Moraceae species in secondary T. grandis L. dominated community.

Trends in Tree Diversity and Stand Structure during Restoration: A Case Study in Fragmented Moist Deciduous Forest Ecosystems of Northeast India

Ecological implications for the conservation of fragmented forests to managed local plant diversity have recently drawn much attention of most conservationists. Present study investigates the importance of fragmented forests using different quantitative measures of species diversity and stand structure as indicators of natural restoration from past disturbances. Eleven independent 500 m × 10 m belt transects (5.5 ha) were established within fragmented low land moist deciduous forests of Tripura. All woody plants ≥10 cm girth at breast height (GBH) were measured. A total of 7,134 individuals with mean density of 648.55 stems ha−1 and 16.36 m2 ha−1 of basal area were recorded, which represented 134 species, 93 genera, and 43 families of woody plants. Diversity-dominance curve showed that maximum number of species were ranked >10 due to low abundance value. Maximum distributions of stems (>50%) were recorded at lowest girth class (10–30 cm) as an indication of advanced regeneration and significantly declined towards upper girth (; ) and height (; ) classes, which also indicated that some plants were adopted with ongoing disturbances through both seeded and nonseeded regeneration. Species richness (; ), dominance (; ), and density (; ) were significantly increased at different disturbance intensities. Disturbances strongly influenced typical community association and structure by increasing diversity and population at certain magnitude and thereby showed declining trend towards maturation. Fragmented moist deciduous forests seek immediate attention as they represent spatial habitat for many economical or ecological important species, thus sustaining local biodiversity for livelihoods.

Effects of patch size, disturbances on diversity and structural traits of tropical semi-evergreen forest in the lowland Indo Burma hotspot: implication on conservation of the threatened tree species

Information on geographic distribution, population and threat status of most globally red listed species in the Indo Burma zone are inadequate. Given the increase in the prevalence of isolated forest patches in the part of this hotspot, evaluation is necessary on how size of the remnant forest patches and on-going disturbances affects structure and diversity of remaining habitats including the population of some globally threatened tree species. Quantitative vegetation inventory by 500 m long and 10 m wide (0.5 ha) line transects were randomly set in nine fragmented tropical semi-evergreen forest patches in Tripura, Northeast India. The studied forests patches grouped into small, medium and large based on their respected sizes. Spatial variability was analysed in woody species diversity and structure along the patch size gradients and their response to both patch size and anthropogenic disturbances. Out of 167 species, 13 identified as red-listed species by IUCN under the present inventory. Most of the diversity and structural parameters showed statistically significant positive response with the forest patch size, except for stand dominance, disturbance, sapling density and number of aggregated distribution pattern decreased when patch size increased. In addition, most of the diversity and structural attributes showed negative response with disturbances. Present baseline data would serve as an effective tool for management and protection of this important forest type. Future habitat restoration programme and strategies for relocation of additional population and re-introduction of those globally threatened trees are recommended.

Lower altitudinal variation in habitat associations, tree diversity and co-dominant population structures along moist deciduous forests dominated by sal (Shorea robusta) in Northeast India

We used line transects of 10 × 500 m size to analyze the patterns of sal associations, diversity and population structure at lower elevation (<100 meters above mean sea level) of moist deciduous forests dominated by sal (Shorea robusta) in Tripura, Northeast India. Overall 216 woody species with 898.56 ha−1 mean density and 33.21 m2 ha−1 mean basal area were recorded using 32 line transects of 0.5 ha size sampled by measuring sal forests at ≥10 cm girth at breast height. Five different sal associations were recognized by cluster analysis, where sal typically associated with Terminalia bellirica, Careya arborea and Schima wallichii in moist deciduous habitats. Rare associations of sal with Artocarpus chama and Dipterocarpus turbinatusa were also identified. Species diversity (p < 0.001) and dominance (p < 0.0001) was significantly different across the sal associations; species richness was recorded higher in S. robusta – S. wallichii association with 152 species than in S. robusta – T. bellirica association with 85 species. Existing habitat disturbances and intensity of sal effects on diversity and structure were significant (p ≤ 0.05), as observed by the changes in species richness and abundance of most abundant, least abundant and unique species along the associations. Population trends and regeneration potential of sal and its most associated trees were predicted using steepness and negative slope values in regression of size class distributions of tree density per hectare at 10 girth classes for each sal association. The present investigation helps in the understanding of broad ecological aspects in lowland sal habitats, particularly when this ecosystem is shifting to these regions in relatively wetter and plain areas due to climate change.

A quantitative checklist of woody angiosperm diversity,population structure and habitat grouping in Trishna Wildlife Sanctuary of Tripura, northeast India

A quantitative vegetation inventory was conducted in Trishna Wildlife Sanctuary of Tripura, Northeast India. Twenty five 500×10 m belt transects were used to record diversity and population structure of woody angiosperms. Overall 289 species belonging to 158 genera and 64 families were recorded at ≥10 cm GBH (Girth at Breast Height). Moraceae (25 spp.), Phyllanthaceae (21 spp.), Leguminosae (21 spp.), Euphorbiaceae (15 spp.), and Rubiaceae (14 spp.) were the top five families with highest species diversity. Habit wise, 226 species were trees, 25 woody shrubs, 23 woody climbers, 6 bamboos, 6 rattan and 3 palm species. Shannon–Wiener diversity index values ranged between 1.42–4.25, and Simpson dominance index ranged between 0.02–0.42. Mean species richness index was 2.83 and species evenness index was 0.78. The present quantitative checklist indicates the potential plant resources of the sanctuary which can be used for future biodiversity inventories and species conservation.

New Distribution Record of Five Species of Xylaria from Tripura, Northeast India

Abstract This retrospective study analyses sex differences in foetal biometry from the 1st trimester onwards, and sexual dimorphism in newborn size of 4260 singleton term births taking place at the Viennese Danube hospital between 2005 and 2013. Crown-rump length was determined at the 11th to 12th week, biparietal diameter, fronto-occipital diameter, head circumference, abdominal transverse diameter, abdominal anterior-posterior diameter, abdominal circumference and femur length were determined at the 20th or 21st gestational week and at the 32nd or 33rd week of gestation. Immediately after birth, birthweight, birth length and head circumference were taken, the Apgar scores 1, 5 and 10 minutes after birth were determined. Significant sex differences were found from the first trimester onwards. With exception of femur length, male foetuses exhibited always the significantly larger dimensions. At the time of birth, male newborns were significantly larger and heavier than their female counterparts. Sex had an independent impact on foetal biometry and newborn size.

Carbon Sequestration Potential and Edaphic Properties Along the Plantation Age of Rubber in Tripura, Northeastern India

India is voluntarily committed towards reducing carbon emission. Rubber plantation could be an important means for carbon sequestration at state and national level. Tripura holds second position as rubber grower state in India, spreading over a 72273 hectare areas. Present study designed to estimate the carbon storage potential, sequestration rate and some selected edaphic properties under four different aged rubber plantations viz. HB05, HB10, HB15 and HB20, following stratified random sampling methodology. Total, 40; 100×10 m transects were laid for estimation of biomass carbon stock and transects were further subdivided into five equal quadrates 20×10 m sized for sampling soil. The stand structural variables like mean girth size, height, basal area, tree carbon and overall carbon stock significantly varied among the different aged rubber plantations. The periodic annual increment in terms of carbon sequestration was estimated at the rate of 2.97, 3.30, 3.14 and 2.82 (Mg C ha-1 yr-1). The result indicated that total carbon stock in rubber plantation was 202.48 Mg ha-1, out of which tree carbon shared 41.85 and Soil Organic Carbon (SOC) 160.71 Mg ha-1 respectively. SOC did not show any significant variation along the plantation ages. The study suggested that the potentiality of carbon sequestration of rubber plantation in Tripura has immense scope for future carbon credit and incentives.

Effects of anthropogenic disturbances on vegetation diversity and structure:a case study in the remnant forests surrounding the village ecosystems of Tripura,Northeast India

The types, frequency, and intensity of human interference with forests markedly affect the vegetation dynamics. Assessment of the impact of anthropogenic disturbances on forest diversity and structure is one of the central issues related to human behaviour and forest ecosystems and management. Both species diversity and density are very sensitive to local anthropogenic disturbance, which can be reduced depending on land-use systems. We used 10 line transects of 500 × 10 m to record and measure all plants ≥10 cm girth in some of the remaining forests surrounding villages in Tripura, Northeast India. To predict the effects of anthropogenic pressure on species richness and forest structure, we recorded and scored all ongoing disturbances in all transects of the forests. Although our study did not show any significant effects on the mean number of species, all diversity indices were significantly affected by disturbance. Total stem density (F = 128.60, p < 0.0001) and basal area (F = 65.30, p < 0.0001) of the forest stands were significantly affected by disturbance. Disturbance significantly (F = 84.81, p < 0.0001) impacts the abundance of mature voluminous trees removed by extensive illegal logging. Further, stem density at the middle (F = 10.01, p < 0.05) and upper (F = 131.70, p < 0.0001) canopy stories was also reduced by high disturbance intensity. The present analysis will be useful to policy-makers and planners for implementation of sustainable forest management at both the local and regional scale.

Do Extensive Rubber Plantation Influences Local Environment ? A Case Study from Tripura, Northeast India

Tripura is the second largest Natural Rubber (NR) producing state of India. As most of the NR plantation in the state is rain dependent, it is observed that fluctuation in monsoon poses a serious threat to plantation growth. The effect of such shift and fluctuation in climate ranges from surface and ground water level variation, air quality and soil preservation. At present no assessment is available to critically review the impact of large scale NR plantation on environment. In the present paper the effect and impact of annual rainfall deficit, depleted ground water level, average local atmospheric temperature variation and rainfall ground water recharge on NR plantation is studied for the state of Tripura. Considering the large scale accelerated NR plantation in the state, an attempt has been made to figure out the consequences related to water management. The multidirectional environmental threat to the state comprising annual rainfall deficit of 23.3 %, depleted ground water level and significant rise in average atmospheric temperature may severely hit the production of NR in the region. Moreover, the estimated requirement of water to produce ribbed smokes sheet (RSS) will may escalate to more than 152140 kiloliters in the next ten years. The predicted amount of waste water generated (directly or indirectly) in RSS collection and industry processing effluents may cause large environmental issue due to their open disposal in many cases. Hence, also claims a threat to the rubber production and growth of the sector.