Dry Tropical Region Of India Research Articles

Vegetation and Soil Dynamics : Insights from Prosopis juliflora- Intruded Areas in Hastinapur Wildlife Sanctuary

Ecological study on plant diversity and soil characteristics of two contrasting sites (Prosopis juliflora-invaded and non-invaded) in Hastinapur Wildlife Sanctuary was undertaken to understand the structure of vegetation and soils and implication of exotic dominance in a dry tropical region of India. Seasonal floristic composition was recorded for one year through monthly visits. Phytosociological study of the two sites in each of three seasons was carried out by sampling a total of 120 quadrats (each 1mx1m, n= 20×3×2). Plant species density and abundance was estimated for both sites in each season. Seasonal surface soil (0–10 cm) samples were analyzed for soil pH, moisture content, organic C, and total N. Species occurrences and their relative abundance data were used to estimate alpha and beta diversity. A total of 76 plant species from 29 families were recorded (Malvaceae, Fabaceae and Asteraceae being top dominants). Maximum flora was recorded in rainy season at both sites, higher at non-invaded sites in all seasons. Beta diversity followed similar trend, higher in rainy season and at non-invaded than invaded sites, highest being 13.2 at non-invaded site in rainy season. Dominants changed with site and season. Vegetation patches were distinct in drier seasons compared to rainy months. Soil organic carbon, total nitrogen and C : N ratios were high at invaded sites compared to non-invaded sites except in summer season. While higher diversity and higher similarity amongst different sites in rainy season indicated a homogenization impact in Indian dry tropical regions, higher diversity at non-invaded site suggested implication of diversity-reducing impact of tree invader Prosopis juliflora.

Importance of Dalbergia sissoo for restoration of degraded land: A case study of Indian dry tropical vindhyan regions

To achieve the UN Sustainable Development Goals and preserve biodiversity and ecosystem services, degraded land must be restored. The focus of the current study was to evaluate the impact of Dalbergia sissoo Roxb (D. sissoo), a multipurpose native Indian tree in restoring degraded land. The significance of this species in restoring the fertility of agricultural soil in the dry tropical region of India was also examined in this study. This study showed an improvement in the soil quality (physical, chemical, biological, and enzymatic properties) of rhizosphere zone of D. sissoo (DL) throughout three seasons (rainy, winter and summer) in comparison to D. sissoo based agricultural soil (AL) and degraded (barren) land soil (BL). Soil moisture and water holding capacity (WHC) was significantly higher in DL in all three seasons compared to AL and BL, whereas, lower soil temperature and bulk density were noted in the rhizospheric soil of DL. The amount of soil organic carbon (SOC) was 75–94% higher in DL rhizospheric soil and 12–20% in the AL compared to BL soil in all three seasons. Total nitrogen (TN) and total phosphorus (TP) in the rhizospheric soil of DL were significantly higher (TN, 0.15–0.17% and TP, 16.1–21%) than those in AL (TN, 0.05–0.06%; TP, 11.4–14.2%) and BL ((TN, 0.03–0.04%; TP, 11.6–10.5%) soils, while C: N ratio was higher in BL (13.2–14.8) than AL (10.8–12.1) and lower in DL (6.5–8.2) soil in all three seasons. The rhizosphere soil of DL had considerably greater levels of microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and soil dehydrogenase activity (SDA) than the AL and BL. Pearson's correlation showed a significant strong positive correlation of SOC with WHC, TN, TP, MBC, MBN and soil dehydrogenase activity (SDA) (p < 0.01). Additionally, the principal component analysis (PCA) showed large and positive loading of PC1 for TN, WHC, MBN, MBC, SOC and SDA, suggesting that the restoration efforts should focus on increasing the TN, MBC, MBN, SOC and SDA. Increased SOC, TN, TP, microbial biomass and SDA in the rhizosphere soil of D. sissoo indicate healthy soil conditions in the Vindhyan dry tropical region of India. Therefore, this study advises to use D. sissoo tree extensively in land restoration initiatives for the benefit of both nat ure and people and also to achieve the goal of the United Nations Decade on Ecosystem Restoration (2021−2030).

Impact of tree plantations on the dynamics of soil aggregates in urban degraded lands in the dry tropics

AbstractThe impact of land‐use change in an urban ecosystem on soil aggregate dynamics and soil carbon storage was studied through two annual cycles under five land uses. All the land uses namely: (1) natural mixed vegetation (NV) growing in a protected area; (2) grass fallow (GF); and tree plantations of (3) Cassia siamea (CP); (4) Jatropha curcas (JP); and (5) Tectona grandis (TP) were grown on urban degraded waste lands in a dry tropical region of India. Proportions of soil aggregate fractions, their stability, and soil carbon storage were analyzed at upper (00–15 cm), and lower (15–30 cm) soil depths during the rainy, winter, and summer seasons. Across all the land uses and at both the soil depths, the proportion of macroaggregate was highest during summer and lowest during the rainy season, whereas the reverse trend was observed for mesoaggregate. The annual mean proportion of macroaggregate decreased while meso‐ and microaggregates increased, with increasing soil depth across all the land uses. At the upper layer, the trends of macroaggregate, aggregate stability, and soil C storage were NV &gt; CP &gt; JP &gt; TP &gt; GF whereas at lower depth, the trend was NV &gt; TP &gt; CP &gt; JP &gt; GF. Across all the land uses in both the depths, soil C storage was strongly and positively correlated with annual mean fraction of soil macroaggregate. All tree plantations improved soil properties considerably as compared to GF at upper soil layer, yet TP reached near NV in these soil properties at lower depth. Soil aggregate fractions may be used as an index of carbon storage capacity in the urban ecosystems.

Impact of land use changes on soil quality and species diversity in the Vindhyan dry tropical region of India

AbstractConversion of forest land into different land use types is the primary cause of degradation of land resources, which in turn alters nutrient and carbon cycles, land productivity and diversity of species. There is scarcity of information about land-use changes (LUC) and their effect on relationship of soil quality and species diversity at landscape level in the Vindhyan dry tropical region. We evaluated the impact of land-use changes on soil physicochemical quality and the influence of these qualities on species diversity and organic matter accumulation. We also established the relationship between soil quality indicators and species diversity parameters. To examine impact of LUC, we did a detailed field survey and analysed selected soil quality indicators by standard methods. We examined species diversity parameters and established the relationship between soil quality and species diversity. We found that there is a marked decline in soil porosity, water-holding capacity and soil moisture due to LUC. Conversion from forest land (FL) to savanna land (SL) resulted in soil organic carbon decreasing by ∼40–50%. The decrease was more pronounced in cultivated land (CL) and degraded land (DL) (65–70% and 83–85%, respectively). In the case of total N, maximum decrease in total N of 83–87% was noted in DL as compared with FL. The poor soil quality indicators in degraded and agricultural land can be explained by the interaction between the soil organic carbon and nitrogen loss with diversity loss. This study recommends that for management/restoration of land resources, planning strategies should consider the current landscape structure, with land-use planning.

Impact of land use change on soil aggregate dynamics in the dry tropics

AbstractA 2‐year study was conducted to elucidate land use change (LUC) impact on the distribution of aggregate size fractions and associated carbon (C) concentration involving natural forest (NF), degraded forest (DF), cropland (CL), and biofuel plantation (JP, Jatropha plantation) in the dry tropical region of India across the soil profile (0–10, 10–20, and 20–30 cm). Across the seasons and the land uses, the proportion of macro‐ and microaggregates was maximum at upper and minimum at lower layer whereas mesoaggregates increase with depth. The trend of macro‐ and microaggregate fractions through the soil profile was NF &gt; JP &gt; DF &gt; CL whereas that of mesoaggregates was CL &gt; DF &lt; JP &gt; NF. Dry mean weight diameter was highest at upper layer and decreased down the depth in all the land uses and followed the trend NF &gt; JP &gt; DF &gt; CL. Aggregate associated organic carbon (OC) concentration in all the fractions decreased from NF to DF, CL, or JP indicates that macroaggregate associated OC concentration was more susceptible to loss than that of meso‐ and microaggregate associated OC concentration. LUC induced decline in macroaggregate associated OC stock and increase in meso‐ and microaggregate associated OC stock; indicated redistribution of OC stock among aggregate fractions. It may be concluded that JP in dry tropics can be an efficient strategy for rehabilitation of degraded land as it improves aggregate structure and stability in the whole profile and aggregate associated OC stock in upper layer of soil.

Metal Contamination and Health Risk from Consumption of Organically Grown Vegetables Influenced by Atmospheric Deposition in a Seasonally Dry Tropical Region of India

Pot-culture experiments showed that organically grown Vicia faba, influenced by atmospheric deposition, accumulated (μg g(-1)) 0.088-3.246 Cadmium, 0.19-42.48 Chromium, 0.0124-30.43 Copper, 0.075-4.28 Lead and 0.63-67.68 Zinc. Similar trends appeared for Abelmoschus esculentus. At high deposition sites, Cadmium, Lead and Zinc exceeded the safe limits of Prevention of Food Adulteration standards. Health risk index for Cadmium, Copper and Lead exceeded the safe limits of United States Environmental Protection Agency. The study suggests that atmospheric deposition could substantially elevate metal levels in organically grown vegetables in 2011.

Use of ethylenediurea for assessing the impact of ozone on mung bean plants at a rural site in a dry tropical region of India

A field study was conducted to evaluate the usefulness of ethylenediurea (EDU) in assessing the impact of ozone (O3) on mung bean plants (Vigna radiata L Malviya Janpriya) grown in a rural area of a dry tropical region of India. Mean monthly O3 concentrations varied between 52.9-64.5 ppb. Significant reductions in growth, yield, soluble protein, pigments, and ascorbic acid in non-EDU-treated plants were observed when compared with EDU-treated plants. This clearly showed that EDU treatment provided protection against negative effect of O3 on mung bean and therefore can be effectively used as a tool to assess phytotoxic O3 concentrations in rural areas.

Atmospheric Deposition and Heavy Metal Contamination in an Organic Farming System in a Seasonally Dry Tropical Region of India

Increased consciousness about agricultural sustainability and health risks associated with agrochemicals has lead organic farming to be a globally emerging alternative farm practice. We report the effect of atmospheric deposition on soil quality and heavy metal contamination of agricultural produce under an organic farming system using wheat and corn as test crops. Data obtained in the open field (OFO) were compared with a plastic-covered glass-house-grown system (OFG). The results showed that depositions of Cd, Cu, Ni, Pb, and Zn increased with time. Soil porosity, water holding capacity, microbial biomass carbon (Cmic), substrate-induced respiration (SIR), alkaline phosphatase, and FDAase activity decreased, whereas the bulk density and contents of Cd, Cu, Ni, Pb, and Zn increased over time in open plots receiving atmospheric deposition. Concentrations of metals in grains in OFO crops exceeded the safe limits of Indian standards and were three to sixfold higher than those recorded in OFG plots. These results indicate that atmospheric deposition of heavy metals can have a destabilizing effect on soil fertility in organic farming and can greatly increase the dietary intake of toxic metals. This may have long–term implications for human health as well as for agricultural sustainability. The data presented here have particular concern for developing countries, where unprecedented urban–industrial growth and consequently increased input fluxes of heavy metals will continue for decades to come.

Accumulation of heavy metals in dietary vegetables and cultivated soil horizon in organic farming system in relation to atmospheric deposition in a seasonally dry tropical region of India

Increasing consciousness about future sustainable agriculture and hazard free food production has lead organic farming to be a globally emerging alternative farm practice. We investigated the accumulation of air-borne heavy metals in edible parts of vegetables and in cultivated soil horizon in organic farming system in a low rain fall tropical region of India. The factorial design of whole experiment consisted of six vegetable crops (tomato, egg plant, spinach, amaranthus, carrot and radish) x two treatments (organic farming in open field and organic farming in glasshouse (OFG)) x seven independent harvest of each crop. The results indicated that except for Pb, atmospheric deposition of heavy metals increased consistently on time scale. Concentrations of heavy metals in cultivated soil horizon and in edible parts of open field grown vegetables increased over time and were significantly higher than those recorded in OFG plots. Increased contents of heavy metals in open field altered soil porosity, bulk density, water holding capacity, microbial biomass carbon, substrate-induced respiration, alkaline phosphatase and fluorescein diacetate hydrolytic activities. Vegetable concentrations of heavy metal appeared in the order Zn > Pb > Cu > Ni > Cd and were maximum in leaves (spinach and amaranths) followed by fruits (tomato and egg plant) and minimum in roots (carrot and radish). Multiple regression analysis indicated that the major contribution of most heavy metals to vegetable leaves was from atmosphere. For roots however, soil appeared to be equally important. The study suggests that if the present trend of atmospheric deposition is continued, it will lead to a destabilizing effect on this sustainable agricultural practice and will increase the dietary intake of toxic metals.

Experiments on Ecological Restoration of Coal Mine Spoil using Native Trees in a Dry Tropical Environment, India: A Synthesis

A series of experiments was conducted on the rehabilitation of mine spoil in a dry tropical region of India for determining the suitability of tree species for plantation, growth performance of selected indigenous species in monoculture and impact of the plantations on the restoration of biological fertility of soil. All of the 17 indigenous species examined could grow in the mine spoil and the growth of a majority of them could be improved by amending the mine spoil with NPK fertilizer. Direct seeding showed greatest height of Zizyphus jujuba and Pongamia pinnata on flat surface, and of Azadirachta indica on slope. In terms of diameter, Syzygium cumini performed best on flat surface and Terminalia arjuna on slope. Total biomass in plantations of selected native tree species on mine spoil at 5-yr age varied from 7.2 to 74.7 t ha−1, being minimum for Shorea robusta and maximum for Dendrocalamus strictus. Total net production ranged from 3.5 (for Shorea robusta) to 32.0 t ha−1 yr−1 (for Dendrocalamus strictus), respectively. Microbial biomass in the redeveloping soil was lower compared to that in natural forest soil but immobilization of soil C in microbial biomass was greater in the mine spoil than in the natural forest. The study indicated that net primary production of the plantations was a function of the amount of foliage, soil C was a function of the amount of litter fall and biomass C was a function of soil C. Plantation of trees significantly accelerated the soil redevelopment process on the mine spoil.

Role of ethylene diurea (EDU) in assessing impact of ozone on Vigna radiata L. plants in a suburban area of Allahabad (India)

A field study was conducted to evaluate the suitability of ethylene diurea ( N-[2-(2-oxo-1-imidazolidinyl)ethyl]- N′-phenylurea; EDU) in assessing the impact of O 3 on mung bean plants ( Vigna radiata L. var. Malviya Jyoti) grown in suburban area of Allahabad city situated in a dry tropical region of India. EDU is a synthetic chemical having anti-ozonant property. Mean monthly O 3 concentration varied between 64 and 69 μg m −3 during the experimental period. In comparison to EDU-treated plants, non-EDU-treated plants showed significant reductions in plant growth and yield under ambient conditions. Significant favourable effects of EDU-application were observed with respect to photosynthetic pigments, soluble protein, ascorbic acid and phenol contents. EDU-treated plants maintained higher levels of pigments, protein and ascorbic acid in foliage as compared to non-EDU-treated ones. The study clearly demonstrated that EDU alleviates the unfavourable effects of O 3 on mung bean plants, and therefore can be used as a tool to assess the growth and yield losses in areas having higher O 3 concentrations.

Litter decomposition and nutrient release in relation to atmospheric deposition of S and N in a dry tropical region

Temporal and spatial variations in litterfall, leaf litter decomposition and nutrient release were quantified along an air pollution gradient around an industrial area in a dry tropical region of India. Significant differences were found in litterfall between the sites. Litter decomposition rates also significantly varied among the study sites. Litter decomposition was faster at sites away from the industrial region with coal-fired power plants. The concentrations of N and P increased, whereas that of Ca and SO 4-S decreased in decomposing litter over time. The nutrient release pattern was also modified by atmospheric deposition. Concentrations of SO 2 and NO 2 were negatively correlated with relative mass loss. Turnover time of nutrients, except SO 4-S in decomposing litter was maximal at the site receiving highest atmospheric depositions. The study documents that industrial emissions significantly modified nutrient cycling in adjacent terrestrial ecosystems.

Effect of soil nitrogen, carbon and moisture on methane uptake by dry tropical forest soils

Methane uptake was measured for two consecutive years for four forest and one savanna sites in a seasonally dry tropical region of India. The soils were nutrient-poor and well drained. These sites differed in vegetational cover and physico-chemical features of the soil. There were significant differences in CH4 consumption rates during the two years (mean 0.43 and 0.49 mg m-2 h-1), and at different sites (mean 0.36 to 0.57 mg m-2 h-1). The mean uptake rate was higher (P < 0.05) in dry seasons than in the rainy season at all the sites. There was a significant season and site interaction, indicating that the effect of different seasons differed across the sites. There was a positive relation between soil moisture and CH4 uptake rates during summer (the driest period) and a negative relation during the rest of the year. The results suggested that seasonally dry tropical forests are a strong sink for CH4, and C and N status of soils regulates the strength of the sink in the long term.

Energetics and environmental costs of agriculture in a dry tropical region of India: V. P. Singh & J. S. Singh, Environmental Management, 16(4), 1992, pp 495–503

Energetics and environmental costs of agriculture in a dry tropical region of India: V. P. Singh & J. S. Singh, Environmental Management, 16(4), 1992, pp 495–503

Energetics and environmental costs of agriculture in a dry tropical region of India

The present article, based on a study of five village ecosystems, assesses the energy efficiency of rain-fed agriculture in a dry tropical environment and the impact of agricultural activity on the surrounding natural ecosystems. Agronomic yield is insufficient to meet the food requirement of the human population, hence 11.5%–49.7% of the required amount of food grains are imported from the market. Energy requirements of five studied agroecosystems are subsidized considerably by the surrounding forest in the form of fodder and firewood. Natural ecosystems supply about 80%–95% of fodder needs and 81%–100% of fuelwood needs. The output-input ratio of agriculture indicated that, on average, 4.1 units of energy are expended to obtain one unit of agronomic energy. Of this, 3.9 units are supplied by the natural ecosystem. In addition, 38% of the extracted firewood is marketed. The illegal felling and lopping of trees result in ever-increasing concentric circles of forest destruction around the villages and together with excessive grazing results in savannization. The forests can be conserved by encouraging fuelwood plantations (0.7 ha/ha cultivated land) and developing village pastures (1.6 ha/ha cultivated land) and reducing the livestock numbers. Agricultural production in the region can be stabilized by introducing improved dry farming techniques such as intercropping, planned rainwater management, and adequate use of fertilizers.