Search

Habitat fragmentation creates numerous small forest patches separated by human land use that may affect the compositional and structural attributes and ecosysem functions particularly the nutrient dynamics in forest ecosystems. We tested this hypothesis along a fragment size gradient in subtropical broadleaved forests in Cherrapunjee area of Meghalaya, northeast India following standard methods of vegetation sampling and nutrient dynamics. The study revealed that the structure and composition of woody species, shrubs and herbs varied significantly (p<0.05) along a fragment size gradient. Similarly, the leaf litter standing crop as well as total litter fall and annual N and P return through litter fall varied significantly (p<0.05) across fragments and were higher in the larger fragments as compared to the smaller fragments. Therefore, the results of the study collectively suggest that understanding the overall ecological implications of the effect of fragmentation on the structure and functioning of subtropical broadleaved forest ecosystem of Meghalaya, north east India, is imperative to outline pertinent conservation strategies. [ABSTRACT FROM AUTHOR]

Tropical Sal forests are gaining wide recognitions due to its multifarious significance. An estimation of vegetational structure and biomass would be helpful for evaluating both productivity and sustainability of the forest ecosystems. Information regarding vegetational biomass, litter mass and fine root biomass, and overall dry matter dynamics are very limited. Therefore, the present work deals the vegetation biomass influenced by four different site quality of Sal dominating tropical deciduous forest of Chhattisgarh, India. The current study provides a framework under which all vegetational attributes can be quantified under varying site quality which is modified by different seasons. Our study revealed a significant increase in vegetational attributes and biomass as per increasing quality of sites. The density value (individuals/ha) and basal area (m2/ha) of tree, sapling and seedling in different sites were ranged from 710 to 1010, 2000 to 2500, 9750 to 14,500 and 33.5 to 46.8, 0.32 to 0.33, 17.96 to 21.43, respectively. The total biomass varied from 187.39 to 383.46 t ha−1. The fine root and forest floor biomass varied between 2.44 and 4.20 t ha−1, and 2.32 and 2.83 t ha−1, respectively among different sites and seasons. The total litter fall varied from 4.18 to 5.69 t ha−1 yr−1 across the site quality. It reflected that highest value of forest floor, litter floor and fine root biomass were seen in site quality (SQ) SQ-I followed by SQ-II, SQ-III and SQ-IV, respectively in different seasons. A great synergy exists among site quality, stand structure and biomass which surely affect ecosystem structure and its functions. Seasonal impacts are another factor that regulates vegetational statistics, forest floor, fine roots and pattern of litterfall in varying site qualities. Thus, a management implication is needed to understand site quality variation which entirely affects vegetational structure and biomass pattern that would help in strengthening sustainable forest management program. [ABSTRACT FROM AUTHOR]

The study aimed to assess dry matter dynamics of forests along treeline ecotone concerning environmental variability, and four representative forests, birch, kharsu oak, Himalayan fir and mixed forest along treeline ecotone (3250–3400 m asl) were selected in Kedarnath Wildlife Sanctuary, Western Himalaya. Temperature, precipitation and humidity data were recorded for complete 3 years (2008–2010). Field inventory for assessment of forest structure and dry matter was carried out in a 200 m transect in each forest along treeline using quadrats of different sizes for tree, shrub and herb layers. The biomass and net primary productivity (NPP) of woody vegetation was estimated using region-specific allometric equations and of the herb layer, by harvesting. Litter quantity and decomposition rates were assessed using litter traps and litter bags, respectively. The dry matter budget of treeline ecotone was represented using a compartment model. The mean annual temperature at treeline was recorded 6.6 ± 0.68 °C with warmest month average temperature of 12.6 ± 1.2 °C. The average forest biomass at ecotone was 33.27 ± 16.97 Mg/0.1 ha, ranged between 8.87 Mg/0.1 ha in open and early successional birch forest to 44.98 Mg/0.1 ha in dense canopy mixed forest. NPP ranged from 1.49 to 2.11 Mg/0.1 ha year−1. The birch forest exhibited the highest efficiency in annual dry matter accumulation in the canopy layer among all forests. The leaf litter decomposition rates (% weight loss) was highest for kharsu oak (74%) after 3 years. The study revealed that Western Himalayan treeline exhibit warmer summer and higher amounts of dry matter storage, production and decomposition rates. These treeline forests showed a higher dry matter assimilation rate and so the potential for carbon sequestration under a warming climate. [ABSTRACT FROM AUTHOR]

This study estimated the total ecosystem carbon stock (TECS) and sediment carbon sequestration rate through burial for fragmented mangrove habitats of Kochi, south-west coast of India. The mean TECS of Kochi mangroves was estimated at 335.33 ± 184.47 t C ha−1, with above ground biomass of 171.68 ± 104.42 t C ha−1, belowground biomass of 83.30 ± 41.98 t C ha−1, litterfall carbon as dead biomass of 7.12 ± 2.81 t C ha−1 and soil carbon stock of 73.22 ± 39.40 t C ha−1. The average historical soil carbon sequestration rate of Kochi mangroves was also estimated as 2.95 t C ha−1 yr−1. The study revealed that there was significant variability in TECS and sediment carbon burial rate among riverine, estuarine and marine mangrove habitats and it appears that, the biological factors especially mangrove plant structure, species, age, litterfall production, crab density, mangrove conversion to aquaculture ponds and other urban pressure played major roles in driving the variability in carbon stocks and storage. While the sediment particle size, bulk density and the environmental settings played a secondary role. Very low TECS and soil carbon sequestration rate was found in aquaculture converted mangrove habitat. The CO 2e of ecosystem carbon stock (496311.20 t CO 2 e) and soil CO 2 burial (10.62 t CO 2 e ha−1 yr−1 respectively) of mangroves of Kochi, revealed that even with high urban pressure and anthropogenic activities which resulted in fragmented distribution, they are still potent in long term carbon sequestration unless it is not further disturbed. Therefore, conservation and restoration of mangrove habitats based on understanding of the regional controlling factors of carbon stock and carbon burial is a need for scientific climate change mitigation efforts. The study will also contribute to fill the gaps in global mangrove carbon stock assessments for avoiding uncertainties. [Display omitted] • High total ecosystem carbon stock and sequestration in the mangrove ecosystem. • Observed significant variability in carbon stock and burial. • Major controls include biological factors and geomorphological differentiation. • Aquaculture has an impact on carbon stock and sequestration. • Mangrove destruction negatively impacts coastal economies. [ABSTRACT FROM AUTHOR]

The present study examined the litter production, decomposition and nutrient release dynamics of Munrochloa ritcheyi, a rare and endemic bamboo species of Western Ghats. The litter production and decomposition were studied using the standard litter trap and bag techniques. The total annual litter production was 2.842 t ha-1 year-1. Litter production followed a triphasic pattern with a major peak in February 2012 and two minor peaks in May and December, 2011. The rate of decomposition in M. ritcheyi was a good fit to exponential decay model suggested by Olson (1963). The decomposition rate constant of M. ritcheyi was 0.009 day-1 and the half-life was 77 days. The decrease in the N and K content of the decomposing litter was continuous whereas P, Ca and Mg showed temporary accumulation phases before final release. The release of nutrients from the decomposing litter was in the order N = Mg > K = Ca> P. [ABSTRACT FROM AUTHOR]

Reclamation of post mining soils by planting trees is of great research interest due to its potential to stabilize mine soils and sequester atmospheric carbon (C). However there are knowledge gaps regarding the effect of different litter quality and biomass on the C sequestration vis-à-vis molecular characterization of soil organic carbon (SOC) in reclaimed mine soils. Hence, an experiment was conducted to determine the effect of litter quality, quantity, and leaf litter decomposition rate on the quality and quantity of carbon sequestered after 14 years of restoration by three representative plant species (Azadirachta indica, Dalbergia sissoo, and Gmelina arborea) which have been frequently used for revegetation of post-mining sites in India. Results indicate that significant amounts of carbon accumulated under different tree species (47.44, 42.34, and 20.17 Mg C ha−1 under A. indica , D. sissoo, and G. arborea plantations resepctively) as compared to recent dump. Decomposition rate constant had a significant relationship with C/N ratio and nitrogen (N) content and therefore tree species (A. indica) with high C/N, lignin/N ratios, and low N content had a significantly lower decomposition rate constant thereby sequestering more carbon, making it the tree species of choice. Among the three tree species studied, G. arborea witnessed the highest litterfall (4635 kg ha−1 yr−1) but had the lowest SOC stock due to the highest decomposition rate constant (0.00229), which established the fact that composition of leaf litter rather than total litterfall played a significant role in carbon sequestration. Furthermore, spectroscopic methods (UV–vis and FTIR) could clearly distinguish differences in functional groups and molecularity of the humic acids derived from plant species of different resource quality and hence can be effectively used in studying the quality of C sequestered. • Leaf litter quality played an essential role in SOC accumulation. • A higher decomposition rate of leaf litter is not suitable for resetting the carbon sequestration. • The absorption intensities observed from FTIR and E 4 /E 6 ratios can be used in studying the quality of C sequestered. [ABSTRACT FROM AUTHOR]

Floristic composition, structure, diversity, biomass, litterfall and net primary productivity (NPP) of tropical evergreen forests on four contiguous hill ranges of Western Ghats, India were studied. The forest on the study site was analysed by randomly laying eight quadrats (20 m × 20 m) within each representative plot of 1 ha. Biomass of the tree and shrub components was estimated using species-specific allometric equations. The litter input was quantified by placing three litter traps (50 cm × 50 cm × 15 cm) in each quadrat. The net biomass accumulation was computed and compared among the sites studied. The stand density ranged from 257 to 644 individuals ha-1 and basal area between 29 and 42 m2 ha-1. Shannon and Simpson's indices ranged from 1.5 to 3.7 and 0.1 to 0.16 respectively, and with beta diversity of 2.01. Total stand biomass averaged from 440 to 571 Mg ha-1, of which trees contributed 90.2-92.2% and remaining 8.8-9.8% by shrubs and herbs. The standing litter ranged from 3.5 to 4.2 Mg ha-1 and litter production from 4.0 to 5.7 Mg ha-1 yr-1. The average NPP was 23.7 Mg ha-1 yr-1, of which 64.7% was contributed by trees, 13.6% by shrubs, 2.7% herbs and 19.1% by litter. Turnover rate and turnover time ranged from 0.93 to 0.95 yr-1 and 1.05 to 1.08 yrs respectively. The study showed that tropical evergreen forests in Brahamagiri and Kadmakal ranges of Western Ghats are ecologically rich both in terms of structure and biomass production compared to other tropical rain forests of the world, however Padnailkannad and Pattighat sites were severely affected by biotic stresses which demand attention for conservation and management of these fragile ecosystems. [ABSTRACT FROM AUTHOR]

Homegardens are one of the oldest forms of managed land use systems characterised by high diversity and complexity of their species structure which in turn contribute to efficient nutrient cycling. Litterfall and decomposition are the two major processes that replenish the soil nutrient pools and endow sustainability to these agroforests. A study was carried out in the village Dargakona, Barak Valley, northeast India to understand the pattern of litter production and litter decomposition in the traditional homegardens. Annual litter production was 6.27 Mg ha−1 with a bimodal distribution pattern and the nitrogen input through litterfall accounted for 48.17 kg ha−1 year−1. Litter decomposition studies for ten multipurpose trees revealed Sapium baccatum and Toona ciliata to be the most labile litter species and the decay rate coefficients varied among the species with differing rates of nutrient release pattern. Such studies can provide information regarding the litter quality of indigenous tree species and help validate farmers planting and management of multiple species which allows for efficient nutrient cycling of the system. [ABSTRACT FROM AUTHOR]

Hooghly–Matla estuarine ecosystem of India is very rich in natural resources and receives large amount of nutrients through litterfall from adjacent mangrove forest. Nitrogen as an important nutrient occurs in various forms and plays a crucial role in the regulation of productivity in this estuarine system. Modelling of nitrogen dynamics from mangrove litterfall and particularly the release of dissolved inorganic nitrogen in this estuarine system is important because of its role in augmenting growth of phytoplankton and other higher plants and all other biological components of grazing food chain. Considering the importance of nitrogen, a dynamic model with seven-dimension differential equation is proposed. In this model, nitrogen of the mangrove litterfall is considered as source and its conversion into different organic and inorganic forms (soil total nitrogen, soil organic nitrogen, soil inorganic nitrogen, total organic nitrogen of water, dissolved organic nitrogen of water, particulate organic nitrogen of water and dissolved inorganic nitrogen of water) are considered as state variables. Some physical and chemical factors and also rate parameters such as nitrogen fraction of litter biomass, litter biomass, redox potential, soil temperature, conversion rates of nitrogen of one form to another form, phytoplankton uptake rate of dissolved inorganic nitrogen, dissolved oxygen, water temperature and water pH are considered as graph-time functions in this model. These data are collected over two years from our field works and experiments. Other rate parameters are calibrated following standard procedure. Sensitivity analysis is performed before calibration. Model simulation results are properly validated with observed data. Sensitivity analysis reveals that the leaching rate of soil organic nitrogen to total organic nitrogen of water and loss rate of soil organic nitrogen as humic acid and fulvic acids are very sensitive parameters in this system. Redox potential plays an important role in the conversion of soil total nitrogen to soil inorganic nitrogen whereas soil temperature is considered to be key factor regulating the microbial activity for the conversion of soil organic nitrogen to soil inorganic nitrogen. Similarly in water, total organic nitrogen of water including dissolved organic nitrogen and particulate organic nitrogen is dependent on soil organic nitrogen. The dissolved organic nitrogen, particulate organic nitrogen and soil inorganic nitrogen ultimately get converted into dissolved inorganic nitrogen and accumulated in water which is taken by phytoplankton and microflora as minerals. [Copyright &y& Elsevier]

The study was conducted to improve our understanding of the effects of forest disturbance on litterfall and patterns of nutrient return in three subalpine forest ecosystems (i.e. Betula utilis-dominated, Abies pindrow-dominated, and Acer mixed broadleaf) of Indian west Himalaya. Total litterfall (t ha−1 yr−1) ranged between 2.6–3.6 and 2.1–2.6 for pristine and degraded stands, respectively. Whereas total litterfall decrease from pristine to degraded stand was about 25–30% in B. utilis and Acer mixed-broadleaf forests, the level of disturbance did not affect total litterfall in A. pindrow (coniferous) forest. Nutrient (N, P, and K) concentrations in litter components of the forests studied also varied across forest types and disturbance intensities. For pristine stands, among all the forests, return of total nutrients via litterfall was higher. The study revealed that patterns of litterfall and nutrient return in the forests studied were sensitive to intensity of disturbance, although sensitivity varied among forest types and nutrient contents. Increased intensity of disturbance greatly affected the total annual amount of nutrient return in broadleaf forests. Maximum impact was recorded in B. utilis forest with a significant decline in nutrient return from pristine to degraded stands (i.e. 64% for N, 38% for P, and 67% for K) . Corresponding values for decline in Acer mixed forest were 17, 13, and 33% for N, P, and K, respectively, whereas in A. Pindrow forest N return was 15% higher and P return was 33% lower. This study indicates that the litterfall and litter nutrient concentrations in these forests are sensitive to the intensity of disturbance, which affects the amount of nutrient return. This will have a strong bearing on forest nutrient cycling. [ABSTRACT FROM AUTHOR]

Seasonal pattern in the resource quality of freshly fallen leaves in a wet evergreen forest floor of Western Ghats was assessed. High resource quality litter was shed during monsoon seasons and low quality litter during the summer season. We propose that the observed variations are related to nutrient source-sink interactions during summer periods and pulse of increased soil nutrient availability and uptake during rainy season, resulting from wind-mediated green leaf fall. Significant seasonal variations in the nutrient content of fresh litter suggest complex decomposition patterns during different seasons of a year. [ABSTRACT FROM AUTHOR]