The mangrove forests are among the most carbon-rich ecosystems on earth and vital to climate change mitigation. Understanding the relationship of forest structural attributes with carbon stock is essential to achieve sustainable conservation of forest ecosystems and their carbon storage. However, little is known about their inter-relationship in the mangrove forest ecosystems. This study was aimed to quantify primary structural attributes such as density, abundance, frequency, basal area, height, and dbh (diameter at breast height); derived structural attributes such as Importance Value Index (IVI), complexity index (Ic), niche width, and diversity indices ( i.e. , species richness, β- diversity, Simpson’s index, Shannon-Weiner index, Pielou evenness index); and vegetation biomass, i.e., above ground biomass (AGB) and below ground biomass (BGB) using the allometric equations for mangroves of Bhitarkanika National Park (BNP), India. To achieve the result, twenty-five sample plots (20 m × 20 m) were laid down in BNP which were distributed in six conserve forest sites. The study recorded 27 species, with the highest IVI of 112.19 for Excoecaria agallocha . The Ic value ranged between 12.18 to 283.87 across sites. The diversity indices showed BNP as a mangrove rich ecosystem. The mean stand biomass was 436.89 ± 59.75 t ha −1 (AGB = 318.79 ± 44.42 and BGB = 118.10 ± 15.39). The total forest biomass, biomass carbon stock, and its CO 2 equivalents of whole BNP were 6.3 Mt, 2.96 Mt, and 10.87 Mt, respectively. A positive correlation for biomass with the basal area ( r = 0.96), stand density ( r = 0.81), IVI ( r = 0.80) and Ic ( r = 0.91) were observed, whereas it showed a negative correlation with species richness ( r = − 0.59) and Shannon-Weiner index (r = − 0.08). This study recommends necessity of site specific conservation approach to increase the structural complexity of degraded forest sites and the carbon storage potential of BNP as a large variation in forest attributes and stand biomass exists across sites.

In view of increasing anthropogenic influences and global changes, quantification of carbon assimilation through photosynthesis has gained tremendous significance. Precise estimation of Gross Primary Productivity (GPP) is essential for several ecosystem models and is typically done using coarser scale satellite data. The mangrove ecosystem, which offers significant protection to the coastal environment, is one of the critical habitats from a global change point of view. Light use efficiency (LUE) was measured using diurnal in situ photosynthetic rate observations for 13 dominant mangrove species for 3 seasons at each of the three mangrove dominant test-sites situated along the east and west coast of India. Variations in photosynthetic rates among these species were studied for 3 seasons that indicated varying responses of mangrove ecosystem at each site. Among all species, Rhizophora mucronata and Sonneratia apetala indicated higher values at two of the test-sites. IRS Resourcesat-2 LISS-IV datasets were used for the estimation of GPP. Mean GPP for all the sites varied from 1.2 to 7.7 g C m−2 day−1 with maximum value of 14.4 g C m−2 day−1. Mean values of GPP varied across the sites, based on its maximum LUE values and available photosynthetically active radiation (PAR). The results provide GPP values at much better spatial resolution for a threatened habitat like mangroves that typically survive in a narrow habitat along the coasts.

The present study aims to estimate the light use efficiency (LUE) of the major mangrove species of Pichavaram Reserve Forests and its seasonal variations with respect to the environmental factors. Sun leaves (L1) and shade leaves (L2) of eight mangrove species were considered for measurements. The diurnal rate of photosynthesis was recorded for every 45 min from 05:00 h to evening 18:00 h using LI-6400XT portable photosynthesis system. This was further integrated to derive total photosynthetic rate for the entire day. LUE was then derived as a ratio of the photosynthetic rate and photosynthetically active radiation (PAR), which is simultaneously recorded using the same instrument. At both the leaf levels, the net photosynthetic rate was found to be higher during the monsoon season for almost all the species, except Aegiceras corniculatum and Avicennia marina. Even though the photosynthetic rate was higher during monsoon, due to considerable variations in the incoming PAR, the LUEs of the mangroves varied highly throughout the seasons. Among all the seasons, the highest LUE was recorded during monsoon season (3.4 g C/mol photon) for the mangrove species Lumnitzera racemosa at both L1 and L2 leaf levels. During post-monsoon, Rhizophora mucronata recorded the highest LUE at both leaf levels (L1: 2.17 g C/mol photon and L2: 3.37 g C/mol photon).

Scleractinian corals represent the foundation species of reef ecosystems. Bleaching is a physiological, cellular response to environmental stresses wherein marine invertebrates including corals expel their endosymbiont, unicellular microalgae or zooxanthellae from their host tissues. Field spectroscopy helps to characterize the health of corals in terms of reflectance spectra or spectral signatures, i.e. reflected light as a function of wavelength. This chapter reports a case study on spectral discrimination of in situ hyperspectral signatures of live, apparently healthy and bleached corals collected from a single colony of Turbinaria peltata (Esper, 1794) sampled from Laku Point reef in Gujarat coast of India. Derivative analyses on the in situ reflectance data identify five narrow windows in the visible light region (green and red light regions) to spectrally discriminate live and bleached coral polyps of the T. peltata species. This study highlights the potential of field spectroscopy in characterizing coral health in situ through non-invasive sampling.

ABSTRACT Mangroves are one of the most productive coastal ecosystems, which act as natural barriers against natural calamities such as cyclones, tide upsurges and tsunamis. Mangrove ecosystems provide natural habitat for a wide variety of flora and fauna, whilst the economic contribution by mangroves for tourism, fisheries and other natural resources is also of paramount importance. This study focusses on the biodiversity of four major regions of Indian mangroves, namely, Bhitarkanika (Odisha), Pichavaram (Tamil Nadu), Chorao Islands (Goa) and Porlob Jig (Andaman and Nicobar Islands). The study aims to monitor the present status of mangroves in Southern and Eastern coasts of India, with the synergistic use of optical and SAR data. The aerial extents of all the Dominant vegetation spatial maps generated revealed that the Bhitarkanika mangroves had the largest extent (14425 ha) among the four mangrove regions. The second largest area recorded was by the Porlob Jig mangroves of the Andaman and Nicobar Islands (9972 ha), followed by the Pichavaram mangroves (788 ha) and the mangroves of Chorao Islands of Goa (603 ha). Decision makers, for taking the necessary conservation and management actions to protect these fragile, vital habitats can ultimately use this data. Key policy insights This paper provides an insight into the major mangrove species of India. It gives a detailed account of the varying mangrove biodiversity in the Eastern and Western coast of India. The prevalence of various kinds of mangroves from different ecosystems were documented. Among these, Rhizophora annamalayana specious was found indigenously in Tamil Nadu.

Insects play a critical role in bringing successful pollination in angiosperms. Mangrove pollination is a poorly studied aspect from scientific community. This particular work investigated the insect visitors and other prospective of mangrove flowers. Twenty two species (i.e., 17 true and 5 mangrove associates) from Bhitarkanika Wildlife Sanctuary and Devi estuary of Odisha state (East coast of India) were selected; plants were pre-marked and visiting insects were recorded starting from 07.00 am to 13.00 pm during the flowering period of each species. Fifty three species of insects which belongs to seven orders, twenty five families and forty four genera were recorded. The highest, i.e., 14 sp. of insects had been recorded from Aegiceras corniculatum which is a small tree and riverine mangrove. Among insects, bees were found as the most common flower visitors (in 82% mangroves) and particularly “honey bee”, i.e., Apis dorsata visited to sixteen mangrove species (i.e., 73% mangroves). Bees, particularly Honeybee (A. dorsata), sweet bee (Lasioglossum sp.) and carpenter bee (Xylocopa pubescens) were actively engaged in pollen dispersal. Resident time and visitation rate supported that bees with highest visitation rate and low resident time were powerful candidates in bringing mangrove pollination. Wasps, beetles and butterflies act more to be foraging species. Facilitation of bee management and particularly supporting apiculture will help to increase pollination successes of rare and threatened mangroves at regional and global level.

Scleractinian corals represent the main functional group in a coral reef ecosystem. So far, very few studies have ever reported how an in situ coral spectra changes with increasing water column purely in a natural environment. This paper reports the results of a unique field experiment wherein water column effects were observed over time on in situ hyperspectral signatures (over a continuous spectral range 400–1350 nm) of three live coral species from Gujarat coast of India. In situ hyperspectral measurements were taken with Analytical Spectral Devices (ASD) FieldSpec3 spectroradiometer having full spectral range of 350–2500 nm and spectral resolution of 3 nm (at 700 nm) and 10 nm (at 1400, 2100 nm). Three coral species, Favia favus, Goniopora planulata and Turbinaria peltata, were selected as case representatives for this study. In exposed condition, all three corals exhibit brown mode of coral reflectance with characteristic triple peaks at 575, 600 and 650 nm. It is observed that water column attenuates the original signature of corals by enhancing the spectral magnitude in the visible region and in inverse fashion in the infrared region. The first derivative spectra clearly bring out the sensitivity of 840-nm channel towards water column. The water column height at which the triple peak pattern gets obscured varies for the three coral species. The spectral reflectance of coral as a bottom substrate continues to remain strong between 700–720 and 1050–1080 nm even in marginally submerged condition.

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Mangroves play a major role in supporting biodiversity, providing economic and ecological security to the coastal communities, mitigating the effects of climate change and global warming. Species level classification of mangrove forest, understanding physical as well as chemical properties of mangrove vegetation, mangrove health, pigments, and levels of stress are some of the key issues for making scientific and management decisions. Hyperspectral remote sensing owing to its narrow bands, yield information on structural details and canopy parameters. Hyperspectral data over Sundarban and Bhitarkanika mangrove forests are analyzed for species discrimination and forest health assessment. In all, 15 mangrove species in Sundarban and 7 mangrove species in Bhitarkanika have been identified and classified using Spectral Angle Mapper technique. In-situ spectro-radiometer data has been used along with AVIRIS-NG hyperspectral data. Based on response of vegetation in blue, red and near-infrared regions, combination of vegetation indices are used to assess mangrove forest’s health. Reduction in NIR reflectance with shift towards lower wavelength has been observed in less healthy groups.

The paper offers models for simulating photosynthesis as a function of empirical variables, such as radiation, temperature, CO2 concentrations, water content in the atmosphere, vapour pressure deficit and relative humidity for sun and shade leaves of Indian red mangrove (Rhizophora mucronata Poir.). The photosynthetic rates were modelled by incorporating a combination of parameters involved in two separate models, viz. biochemical photosynthetic model and stomatal conductance model together with some additional variables as inputs to twostage least squares fitting regression method. The results revealed good performance of the models in simulating the photosynthetic rates (in most of the cases validation R-2>0.7 and in some cases as high as 0.92).

Imaging radars provide information that is fundamentally different from sensors that operate in the visible and infrared portions of the electromagnetic spectrum. The Indian Space Research Organisation (ISRO) has launched a multi-mode, multi-polarization Synthetic Aperture Radar (SAR) on-board Radar Imaging SATellite-1 (RISAT-1) on 26 April 2012. Various data products from RISAT-1 SAR are now going through calibration-validation (cal-val) phase and soon will be available for the global users for operational and research purposes. In this regard, algorithms are being developed to retrieve various parameters in diverse application areas. This article deals with the in-house algorithm development for studying different resources using initial available data of RISAT-1.

Conservation and wise use of wetlands has been given priority world over. India harbours diverse types of wetlands. This study highlights the findings of the national-level inventory and assessment of wetlands carried out using RESOURCESAT-1 LISS-III data of 2006-07 at 1 : 50,000 scale. A hierarchical system comprising 19 classes based on Ramsar definition has been used to classify the wetlands of India. The extent of wetlands has been estimated to be 15.26 m ha. Inland wetlands account for 69.22% (10.564 m ha), whereas the coastal wetlands account for 27.13% (4.14 m ha). The high-altitude wetlands (situated > 3000 m asl) in the Himalayan states were also mapped, comprising 126,249 ha of areal extent. The status of wetlands in terms of water spread, turbidity of open water and aquatic vegetation has shown significant variation during pre- and post-monsoon seasons. This article highlights the detailed results at state level and the status of wetlands in terms of water spread, aquatic vegetation and turbidity of open water in the wetlands in the pre- and post-monsoon seasons.

The hydrologic variability greatly influences the structural components of wetlands that have a great bearing on habitats for avifauna, aquatic fauna including fish etc. This paper highlights the results of a study carried out to derive changes in open-water and vegetation, and also water balance for Nalsarovar Lake, Gujarat. MODIS 8-day composite data for three consecutive years viz 2002/03, 2003/04 and 2004/05 were used to study the seasonal and inter annual dynamics of water regime in the lake. Digital elevation model derived using Shuttle Radar Topographic Mission data with interpolated bottom topography was used to generate elevation contours and compute water volume from water spread data. The reference data of 2002 (drought year) shows the maximum extent of wetland to be 8.06 km 2 with emergent vegetation of recorded as 2.36 km 2 and open-water as 5.70 km 2 . The rainfall has an impact on the preferred habitat availability for various species of avifauna and it is noted that emergent vegetation present in the lake completely dried up by summer 2002, a rainfall deficit year but revived again in the preceding year i.e. 2003 which was a good rainfall year with 46.68 km 2 under emergent vegetation and 61.96 km 2 under open-water. The 2002 being a drought year has shown very low reference storage (0.256 MCM), which has shown a gradual decrease in the storage to 0.00019 MCM in March 2003. The reference storage also registered a steep increase to 18.165 MCM in October 2003 and decreased 1.264 MCM in March 2004. From this study it is evident that water level of about 9 m elevation at the end of the rainy season is found to be optimal for maintaining various habitats that in turn support the avifauna for the rest of the lean period.

The landslides are one of the most important types of natural hazards. Large landslides create loss of both human life and property. However, people living in the mountainous regions are accustomed to live with them. With the increased tourism over the past few decades, residential areas have spread over mountainous slopes, which naturally require new communication system. This tampers the natural slopes and environment of the mountainous regions, thereby increasing susceptibility to landslides occurrence.

The landslide hazard zonation of Dharasu-Tehri -Ghansali area of Garhwal Himalaya has been carried out using Indian Remote Sensing (IRS) LISS II and SPOT (MLA) data for various geo-environmental parameters viz. lithology, structure, land use/land cover, slope and drainage. The forest types and density and other land uses in the reservoir rim area were delineated and also assessed the direct loss of forests, agricultural land, wastelands and other landuse in the submergence area of the Tehri dam. There are 71 landslides in the periphery of the Bhagirathi and the Bhilangana rivers, which will enclose the impounded reservoir. Out of 71 landslides 35 will get submerged during the reservoir-filling phase while remaining will continue to exist. By overlaying the thematic maps in Geographical Information System (GIS) environment and using statistical parameters, a landslide hazard zonation map has been prepared. Phyllite, dissected hills, slope 50°-60°, agriculture and convex side of stream channel were to be found more susceptible for landslide. An area of 43.5 km2 in the reservoir rim falls in the category of high to very high class as per the landslide hazard zone code.

Conservation of wetland is considered paramount in view of its ecological significance. The availability of reliable and up-to-date data on seasonal water spread, tropic state of wetland and bio-physical parameters besides the landuse/cover of the catchment area is a prerequisite for ‘wise use’ of any wetland ecosystem. The present study is carried out to identify the above parameters of Loktak notified wetland through visual interpretation of 1RS IA/IB LISS II FCC of 1990 and 1994/95. It indicates that the water spread of the lake is showing a declining trend and an increasing trend for aquatic vegetation. In 1990 post-monsoon data water spread was 15441 ha which become 11166 ha in October 1994. The extent of water spread further decreases by pre-monsoon season and was found to be 7875 ha in the IRS LISS II data of March 1995. Like-wise area under aquatic vegetation and associated marshy/ swamps was 10499 ha in October 1990 and 13506 ha in October 1994. Catchment of Loktak lake (104872 ha) is highly degraded and forest covers only 7205 ha area. Agriculture is the main land use (35576 ha) in the catchment and substantial area is also under land with or without scrub. Thus, there is a need to rehabilitate the catchment by way of planting trees for reducing silt load in the Loktak lake and ensuring its ‘wise use’.