Odonata of Puducherry, Union Territory of Puducherry, India: an updated checklist and distributional insights

BackgroundIndia is rich with biodiversity, which includes a large number of endemic, rare and threatened plant species. Previous studies have used DNA barcoding to inventory species for applications in biodiversity monitoring, conservation impact assessment, monitoring of illegal trading, authentication of traded medicinal plants etc. This is the first tropical dry evergreen forest (TDEF) barcode study in the World and the first attempt to assemble a reference barcode library for the trees of India as part of a larger project initiated by this research group.Methodology/Principal FindingsWe sampled 429 trees representing 143 tropical dry evergreen forest (TDEF) species, which included 16 threatened species. DNA barcoding was completed using rbcL and matK markers. The tiered approach (1st tier rbcL; 2nd tier matK) correctly identified 136 out of 143 species (95%). This high level of species resolution was largely due to the fact that the tree species were taxonomically diverse in the TDEF. Ability to resolve taxonomically diverse tree species of TDEF was comparable among the best match method, the phylogenetic method, and the characteristic attribute organization system method.ConclusionsWe demonstrated the utility of the TDEF reference barcode library to authenticate wood samples from timber operations in the TDEF. This pilot research study will enable more comprehensive surveys of the illegal timber trade of threatened species in the TDEF. This TDEF reference barcode library also contains trees that have medicinal properties, which could be used to monitor unsustainable and indiscriminate collection of plants from the wild for their medicinal value.

Pollination and breeding systems of woody plant species in tropical dry evergreen forests, southern India

Species diversity, population structure, abundance and dispersion patterns of all woody plants ≥10cm gbh were inventoried in two 1-ha plots of tropical dry evergreen (sacred grove or temple) forests at Kuzhanthaikuppam (KK) and Thirumanikkuzhi (TM) on the Coromandel coast of south India. Site KK is a stunted forest (average tree height ca 6 m) and TM a tall forest (average tree height ca 10 m). A total of 54 species (in 47 genera and 31 families) were recorded. Species richness and stand density were 42 and 38 species and 1367 and 974 individuals ha−1 respectively for the sites KK and TM. About 50% of the total species were common to both the sites. Site TM is twofold more voluminous (basal area 29.48 m2 ha−1) than KK (basal area 15.44 m2 ha−1). Nearly one third of the individuals are multi-stemmed in the low-statured site KK whereas one fourth of the tree density is multi-stemmed in TM. Species abundance pattern varied between the two sites. The abundance of three species in KK and two species in TM is pronounced. Memecylon umbellatum, the most abundant species contributing to one third of total stand density in KK, is least represented in TM. Species richness, density and diversity indices decreased with increasing girth threshold. Most species exhibited clumped dispersion of individuals both at 0.25 and 1-ha scales. Population structure for girth frequency is an expanding one for both the sites, except for basal area distribution in KK. Variations in plant diversity and abundance are related to site attributes and human impacts. In the light of habitat uniqueness, species richness and sacred grove status, the need for conservation is emphasized.

Aims: To evaluate tree community fruit fall across selected tropical dry evergreen forest (TDEF) sites along the southern Coromandel Coast of Tamil Nadu. Study Design: Quantitative field-based investigation. Place and Duration of Study: Forest sites located in Nagapattinam and Tiruvarur districts of Tamil Nadu; study duration of one year. Methodology: Fruit fall was quantified in three tropical dry evergreen forest sites along the southern Coromandel Coast over a one-year period from January to December. Of the three sites, Jambavanodai (JI) and Thillaivilagam (TV) are situated in Thiruvarur district, while Pushpavanam (PM) lies in Nagapattinam district. In each site, a 100m × 100m (1 ha) permanent plot was established and subdivided into twenty-five 20m × 20m subplots. At the center of each subplot, a 50 cm × 50 cm sampling quadrat was demarcated using locally available pebbles, resulting in a total of 25 sampling units per site. Stone-block–lined, denuded quadrats were employed for the collection of fallen fruits. Fruit litter was collected fortnightly from each sampling quadrat throughout the study period. Collected material was sorted to species level and oven-dried at 80 °C for 48 hours to attain constant dry weight. Results: Total tree community fruit fall across the study sites amounted to 1126.39 kg (dry weight), with a mean annual fruit fall of 375.46 ± 144.44 kg ha⁻¹ yr⁻¹. Fleshy fruits contributed a greater share of total fruit fall than dry fruits across all sites. Fruit fall occurred year-round, with a pronounced peak during September, coinciding with the monsoon period. Mean monthly temperature showed a significant positive relationship with fruit fall at all three sites. Similarly, mean monthly rainfall was positively correlated with fruit fall. Conclusion: The observed positive relationships between fruit fall and both rainfall and temperature are consistent with earlier studies. The findings contribute valuable quantitative information on tree fruit fall dynamics to the ecological database of Indian tropical dry evergreen forests.

The central area of the Coromandel Coast, southeastern India, has been subject to a very long history of human habitation and land use change, substantially reducing the coverage of native forest. There are polarised views about definitive characteristics of native tropical dry evergreen forest (TDEF), albeit agreement that the habitat type is locally characteristic though now severely reduced, fragmented and degraded. A literature review was undertaken to determine the evolutionary origins of TDEF as well as its characteristics. A combination of both natural and human factors gives rise to TDEF, explaining the heterogeneity of existing stands even in close proximity to each other. Religious shrines are often associated with ‘sacred groves’, which are influential in the survival of stands of TDEF. These remaining stands are highly fragmented across the wider landscape and subject to species invasions from adjacent habitats as well as increasing human pressures. On the basis of existing evidence, it is not possible to describe TDEF through a definitive community of tree species, though typical constituent species are listed. TDEF may therefore be representative of a larger biome, as for example ‘tropical rainforest’, rather than a specific vegetation type. Nevertheless, there is general consensus about the importance of restoring TDEF, including its many associated plant and animal species, many of which have medicinal, spiritual and other uses and meanings. Regardless of biological definitions of TDEF, the functions it performs and the diversity of ecosystem services that it provides afford it substantial importance and reinforce the case for its protection and restoration. Successful local restoration activities highlight the feasibility of regeneration of TDEF, even from severely degraded and eroded land, and the associated regeneration of ecological and socio-economic values.

Tropical forests act as a great carbon reservoir covering about 30% of the global carbon content, however, structural alteration of these forests caused by forest disturbances adversely affects the carbon cycle. One such structural change happening in these tropical forests is the increasing dominance of lianas (woody climbers). Among various tropical forest types, lianas are an integral constituent of the tropical dry evergreen forests (TDEFs) found in peninsular India. A re-inventory of lianas was carried out to observe temporal changes in basal area and carbon stock in two 1-ha permanent plots of two disturbed tropical dry evergreen forest sites (TDEF; Oorani -OR and Puthupet - PP) over a 19-year interval (2001-2020). The total basal area in OR and PP increased respectively by 2.26 m2 ha-1 and 0.93 m2 ha-1. The total biomass and the carbon stock in OR and PP increased by 82% and 51% respectively. The dominant species Strychnos lenticellata showed an increase in its basal area by three-fold in OR, whereas, in PP, a marginal increase of 4% was observed. The lower diameter class (1-6 cm) showed an increase in basal area in OR and PP by 101% and 16% respectively. The mid-diameter class (6-11 cm) was the top contributor of the total biomass/carbon in both OR and PP in the latest re-inventory (2020). The present results show that lianas, although known to negatively affect the forest biomass/carbon stock, play an important role in carbon sequestration, thus providing insights into their ecological importance which will certainly be useful in proposing strategies for the conservation of this forest type dominated by lianas.

Developed-developing world partnerships for sustainable development (3): Reducing carbon sequestration uncertainties in south Indian tropical dry evergreen forest

Qualitative reproductive traits of 84 plant species belonging to 41 families were studied in tropical dry evergreen forest on the Coromandel coast of India. Majority of species had rotate type, white-coloured, scented flowers, rewarding nectar and pollen and pollinated chiefly by bees. An association between floral traits and pollination spectrum is evident. Bee pollination was prevalent in pollination systems. Among the fruit types, drupe and berry were common in black and red colour respectively, and dispersed by zoochorous mode. Seeds of brown- and green-coloured dry fruits, without any reward were disseminated by wind and explosion. The reproductive phenophase of trees and lianas occurred mostly during the dry period from January to June, which receives rainfall of less than 50 mm a month. However, shrubs showed a peak in flowering and fruiting in wet period. Detailed phenological observations of 22 woody species revealed a seasonal and unimodal pattern in flowering. Although some species were in flower round the year, flowering activity was skewed towards the dry season. The fruiting activity showed a bimodal pattern, one peak in dry season and another in wet season. Many species displayed a temporal aggregation in flowering and fruiting. The significant relation was obtained between reproductive traits and phenology of plants in the tropical dry evergreen forest.

Fruiting phenology in a tropical dry evergreen forest on the Coromandel coast of India in relation to plant life-forms, physiognomic groups, dispersal modes, and climatic constraints

Seasonality in fine root standing crop and production was studied in two tropical dry evergreen forests viz., Marakkanam reserve forest (MRF) and Puthupet sacred grove (PSG) in the Coromandel coast of India. The study extended from December 89 to December 91 in MRF and from August 90 to December 91 in PSG with sampling at every 2 months. Total fine interval. Mean fine root standing crop was 134 g m−2 in MRF and 234 g m−2 in PSG. root production was 104 g m−2 yr−1 in MRF and 117 g m−2 yr−1 in PSG. These estimates lie within the range for fine roots reported for various tropical forests. Rootmass showed a pronounced seasonal pattern with unimodal peaks obtained during December in the first year and from October–December in the second year in MRF. In PSG greater rootmass was noticed from June–October than other times of sampling. The total root mass in MRF ranged from 114 to 145 g m−2 at the 13 sampling dates in the three sites. The live biomass fraction of fine roots in MRF ranged from 46 to 203 g m−2 and in PSG it ranged from 141 to 359 g mm−2 during the study periods. The dead necromass fraction of fine roots ranged from 6 to 37 g m−2 in MRF and from 12 to 66 g m−2 in PSG. Fine root production peaked during December in both the forest sites. The necromass fraction of newly produced roots was negligible. Total N was slightly greater in PSG than in MRF. Whereas total P level was almost similar in both the sites. The study revealed that season and site characteristics influenced fine root system.

Mangroves are salt–tolerant forest ecosystems of tropical and subtropical intertidal regions of the world. There may be no other group of plants with such highly developed morphological and physiological adaptations to extreme conditions. They are a rich source of steroids, triterpenes, saponins, flavonoids, alkaloids and tannins. The Pondicherry region in South India has no forest, but has scattered patches of mangroves and remnants of tropical dry evergreen forest in the form of sacred groves. The present study documents the directly observed diversity of true mangroves and their associates, in four geographical regions of Pondicherry in South India; namely Pondicherry, Karaikal, Mahe and Yanam. These places are far from one another and the mangrove species diversity varies from one place to another, due to factors such as climate, tidal factors and anthropogenic pressures. In addition, we have also developed a knowledgebase entitled “Mangroves of Pondicherry”, which contains information including botanical name, English name, local name (Tamil language), Family, description, images and common uses of true mangroves and their associates. This knowledge resource is available for open access at http://web.iitd.ac.in/~sundar/mangroves/. Key words: Mangroves, knowledgebase, sacred groves, tropical dry evergreen forest, Pondicherry, South India

Aims: Quantitative field study was conducted to assess forest regeneration status in ten tropical dry evergreen forest (TDEF) sites at southern Coromandel Coast. Study Design: Quantitative field survey. Place and Duration of Study: Tamil Nadu, One year Methodology: Forest regeneration study was conducted in ten tropical dry evergreen forest sites located on the southern Coromandel Coast. A twenty 10 m × 10 m (100 m2; 0.01 ha) square plots were randomly laid in all forest sites. All encountered plants were identified to species level in the field. Individuals up to the height <20 cm were considered as seedlings, whereas the height classes 20.1-40 cm, 40.1-100 cm, and 100.1-<10 girth at breast height (gbh) cm were considered as saplings. Height class classification followed Induchoodan (1993). Regeneration status of species was identified with density of seedlings, saplings, and adult plants. Five regeneration categories were recognized as in Shankar (2001): 1. Good regeneration: Seedlings > saplings> adults; 2. Fair regeneration: Seedlings > saplings ≥ adults; 3. Poor regeneration: (i) Species survives only as saplings but not as seedlings; (ii) Seedlings < saplings < adults; 4. No regeneration: Species absent both in seedlings and saplings but present as adults; and, 5. New regeneration: Species present only in seedlings or saplings but not as adult trees Results: A total of 51640 seedlings were recorded from ten study sites. Seedling density varied from 1970 to 9050 ha-1. On an average each site had 5163 ± 2507 seedlings ha-1. A sum of 38130 saplings was encountered. Sapling density ha-1 ranged from 1560 to 7670 plants ha-1, while the mean sapling density was recorded as 3813 ± 1954 plants ha-1. Species richness of young plants ha-1 varied from 25 to 33 in study area. The mean species richness of the study area was 28.5 ± 3.20 species ha-1. On average, each mature individual had 11.84 ± 2.94 young plants in the study area. Young-mature plant ratios differed from 7.27 to 14.78. The proportion of species showing good, fair, poor and no regeneration varied considerably among study sites. The present investigation recorded a net loss of 3.11 to 43.78% of seedlings during the seedling-sapling transition stage, and a further loss of 66.44 to 84.4% of saplings in the developmental phase from saplings to trees. The seedling survival rate ranged from 5.61 to 12.10%. Conclusion: The mean young plant density, diversity, and species richness obtained in the recent study are comparable with those of the world’s tropical forests.

Tropical dry evergreen forests (TDEFs) occur as patches along the Coromandel coast of peninsular India. Investigations on plant biodiversity, bioresource values, and conservation status of 75 TDEF sites were carried out. A total of 149 woody plant species representing 102 trees, 47 lianas, and three native herbs were enumerated. Across 75 sites studied, species richness of woody plants ranged from 10 to 69 species. Physiognomically, evergreen species dominated the forest. Forest growth determined as girth increment ranged from 0.37 to 1.08 cm yr−1 for trees and 0.39 to 0.41 cm yr−1 for lianas. At the community level, seasonal flowering with unimodal dry season peak and year-round, bimodal fruiting pattern prevailed. A strong association between the qualitative reproductive traits and pollination and dispersal spectrum among the TDEF species has been demonstrated. In bioresource assessment, 150 medicinal plant species, used for treating more than 52 ailments, were documented. Site disturbance scores were obtained by assessing the various site disturbances such as site encroachment, resource extraction, grazing, fragmentation, weed invasion, etc. Conservation significance of the TDEF sites is emphasized in the light of restricted geographical distribution, moderate level of plant species diversity, representation of the unique forest type, high productivity, and bioresource potential. Restoring the disturbed sites with characteristic TDEF species, and revitalizing the cultural traditions associated with sacred groves by promoting awareness of the ecological and bioresource values of TDEFs, are recommended.

There are very few studies about soil chemical and biological properties under tropical dry evergreen forest Coromandel Coast, India. The present study was conducted in six tropical dry evergreen forests sites such as Oorani, Puthupet, Vadaagram, Kotthatai, Sendrakillai and Palvathunnan. We measured the quantity of soil chemical, biological properties and selected soil microorganisms for investigating the impacts of soil microbial populations on soil chemical and biological properties. The result showed that total N, P, Ca, S, Fe, Mn, Cu, Co, exchangeable K, Olson P, extractable Ca and phosphobacterial population were higher in the soil from Kothattai forest site. Organic carbon, total Mg, extractable Na, soil respiration, β-glucosidase activity, bacterial population, fungi population and actinomycetes population were higher in the soil from Palvathunn forest site. Total K, NH4 ＋-N, NO3 −-N, exchangeable K, extractable Ca, extractable Na, azotobacter population, bacillus population and rhizobacteria population were higher in the soil from Sendrakillai. Beijerinckia population, rhizobacteria and soluble sodium were higher in Puthupet forest soil. Total Si, total Na and exchangeable K were higher in soil from Oorani forest site. Total Mo and exchangeable K were higher in the soil from Vadaagaram forest site. The results showed that organic carbon, total N, NH4 ＋-N, NO3 −-N, extractable P, extractable Ca, soil respiration and β-glucosidase were significantly correlated with soil microbial populations. Therefore soil microorganisms are important factor for maintaining soil quality in tropical dry evergreen forest.

This study estimates the existing eco-physiological traits relationship between leaf area (LA) and wood density (WD) in tropical dry evergreen forests (TDEFs) of southern Coromandel Coast, peninsular India. Leaf area and wood density of 56 tree species belonged to 49 genera and 28 families were measured to understand the relationship between the traits. Leaf area and wood density were estimated with standardised protocols. On average, each species had 3400 ± 3040 mm2 LA and 0.74 ± 0.16 g cm−3 WD. On average, each site had 2.44% of total soil organic carbon, 0.11% of nitrogen and 15.7 µg g−1 of phosphorus. The ratios of carbon–nitrogen varied from 16.2 to 32.6 (mean = 22.4 ± 4.92) and of nitrogen–phosphorus ranged from 12.7 to 19.6 (mean = 70.5 ± 15.1). The relationship between leaf area and wood density was negative and significant (r 2 = 0.34, n = 56, P < 0.005; t 54 = 9.07, P < 0.001). There was no significant difference recorded between mean LA and WD of evergreens and deciduous species. Oligotrophic habitat, semi-aridness and longer dry periods are few of the possible reasons behind the profuse occurrence of small-leaved, dense wooded evergreens in tropical dry evergreen forests.