Showing papers in "Tropical Ecology in 2020"

Tree biomass and carbon stock: understanding the role of species richness, elevation, and disturbance

Abstract: Six elevation zones viz., MHF 1 to MHF 6 (Mahendragiri Hill Forest) starting from 229 to > 1505 m asl were assessed to estimate the biomass and carbon stock in tropical dry deciduous forests of Mahendragiri Hills, Eastern Ghats. It aims at establishing a relationship among stem density, biomass, and carbon stock along the elevation gradient and disturbance regime. Each zone considered twenty plots for the investigation (0.05 ha; 50 × 10 m). All the trees ≥ 1 cm girth at breast height were enumerated, and the non-harvest method was used to assess the biomass. The tree biomass ranged from 129.05 Mg/ha in MHF 1 to 255.87 Mg/ha in MHF 2; with the total carbon stock also followed the same trend. The Soil Organic Carbon percentage ranged from 0.70 ± 0.24 to 1.43 ± 0.15 and 0.55 ± 0.22 to 1.13 ± 0.42 in the top and bottom layers, respectively. The results suggest the insufficiency of significant influence on tree biomass by elevation, species richness, diversity, and stem density. The disturbance score generated from the quantification of the frequency of occurrence of different disturbances showed high values in MHF 3 and MHF 1 among the six elevation zones. The disturbance has a more significant impact on the biomass. The highest carbon stock accumulation in MHF 2 could be due to the presence of abundant, large-diameter trees. The total SOC estimated in different elevation zones showed a strong significant positive correlation with elevation. The present research would give an insight for proper management of the declining tropical dry deciduous forests.

High blue carbon stock in mangrove forests of Eastern India

Abstract: Present study focuses on the carbon sequestration potential of five dominant mangrove species (Avicenia marina, Avicenia officinalis, Excoecaria agallocha, Rhizophora mucronata and Xylocarpous granatum) in Bhitarkanika and Mahanadi mangrove ecosystem. Water and soil parameters were sampled and analyzed for 10 selected stations along with aboveground biomass (AGB) and aboveground C (AGC) values. AGB value in the study area ranged from 15.00 ± 2.12 to 70.09 ± 6.68 tha−1 for A. marina, 26.13 ± 3.19 tha−1 to 616.94 ± 50.15 tha−1 for A. officinalis, 3.56 ± 0.96 tha−1 to 98.66 ± 5.24 tha−1 for E. agallocha, 7.06 ± 2.21 tha−1 to 224.41 ± 21.20 tha−1 for R. mucronata, and 0.64 ± 0.21 tha−1 to 6.25 ± 1.52 tha−1 for X. granatum, respectively. AGC value ranged from 7.63 ± 1.08 to 35.65 ± 2.63 tha−1 for A. marina, 1.73 ± 0.01 tha−1 to 280.83 ± 21.29 tha−1 for A. officinalis, 1.64 ± 0.41 tha−1 to 44.95 ± 2.53 tha−1 for E. agallocha, 3.44 ± 1.45 tha−1 to 114.05 ± 10.29 tha−1 for R. mucronata and 0.31 ± 0.10 tha−1 to 3.25 ± 0.31 tha−1 for X. granatum, respectively. The average SOC values in tha−1 varied from 3.52 ± 0.12 to 7.71 ± 0.45. The total carbon (AGC + SOC) calculated for the study area varied from 55.20 ± 7.90 to 330.41 ± 111.97 tha−1 with a mean total carbon of 124.11 ± 30.14 which is equivalent to 455.47 ± 110.56 tons of CO2. Considering the total area of Bhitarkanika and Mahanadi mangrove ecosystem (672 + 141,589) to be 142,261 km2, the mean CO2e be 455.47 ± 110.56 tones, it is approx. 64,795,617.67 ≅ 64.80 TgC that were absorbed from the atmosphere, thus reducing the amount of carbon dioxide from the atmosphere.

Environmental determinants of plant associations and evaluation of the conservation status of Parrotiopsis jacquemontiana in Dir, the Hindu Kush Range of Mountains

Abstract: Hindu Kush is the largest mountain range of Central Asia that forms part of a vast alpine zone that stretches across the Eurasia from east towards the South Asia. We studied vegetation structure and the role of edaphic and topographic factors on distribution and formation of plant associations with specific emphais on Parrotiopsis species of the Districts Dir regions in the Hindu Kush Mountains. We also assessed the conservation status of Parrotiopsis jacquemontiana, an endemic species of the western Himalayan floristic province. We hypothesized that edaphic and climatic factors were responsible for the formation of different plant associations each with distinct indicators. A combination of transect and quadrat based methods were used for sampling. We used two way cluster analysis (TWCA), cluster analysis (CA), indicator species analysis, detrended correspondence analysis and canonical correspondence analysis to analyze and elaborate the vegetation pattern and formation. We used Google Earth Path software (V 1.4.6) for the calculation of extant of occurrence (EOO) and area of occupancy (AOO) for evaluation of conservation status of P. jacquemontiana. A total of 142 plant species were reported belonging to 62 families. CA and TWCA clustered four plant associations within altitudinal range of 1556–2313 m. Parrotiopsis jacquemontiana should be designated as endangered species under ‘EN A2acd; B1B2 bc (i, ii, iii) of IUCN red list categories and criteria in the region. We found that high phosphorous and potassium concentration, elevation, aspect, slope, lower pH, electrical conductivity and soil texture were significant environmental variables that play an important role in the determination of vegetation structure, formation of plant associations and its indicators in the region. This information will be useful for conservation and management practices for endemic and rare plant taxa, and evaluation of vegetation structure.

Synergetic use of in situ and hyperspectral data for mapping species diversity and above ground biomass in Shoolpaneshwar Wildlife Sanctuary, Gujarat

Abstract: Biodiversity loss in tropical forests is rapidly increasing, which directly influence the biomass and productivity of an ecosystem. In situ methods for species diversity assessment and biomass in synergy with hyperspectral data can adeptly serve this purpose and hence adopted in this study. Quadrat sampling was carried out in Shoolpaneshwar Wildlife Sanctuary (SWS), Gujarat, which was used to compute Shannon–Weiner Diversity Index (H′). Above ground biomass (AGB) was calculated measuring the Height and Diameter at Breast Height (DBH) of different trees in the sampling plots. Four spectral indices, namely Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Photochemical Reflectance Index (PRI), and Structure Insensitive Pigment Index (SIPI) were derived from the EO-1 Hyperion Data. Spearman and Pearson’s correlation analysis was performed to examine the relationship between H′, AGB and spectral indices. The best fit model was developed by establishing a relationship between H′ and AGB. Fifteen models were developed by performing multiple linear regression analysis using all possible combinations of spectral indices and H′ and their validation was performed by relating observed H′ with model predicted H′. Pearson’s correlation relation showed that SIPI has the best relationship with the H′. Model 15 with a combination of NDVI, PRI and SIPI was determined as the best model for retrieving H′ based on its statistics performance and hence was used for generating species diversity map of the study area. Power model showed the best relationship between AGB and H′, which was used for the development of AGB map.

Assessment of shifting cultivation fallows in Northeastern India using Landsat imageries

Abstract: Shifting cultivation (Jhum) has been a threat to the rich biodiversity of Northeastern India (NEI). Here, we applied an integrated spectral enhancement technique to map the shifting cultivation fallow/ current jhum area in NEI for 2014, 2016 and 2018 using Landsat-8 data. The natural vegetation in shifting cultivation fallow land was analyzed through field sampling. Manipur state occupied the highest shifting cultivation fallow area of 1528.5 km2 (2014), and it was minimum in Tripura state with 178.3 km2 (2018). The shifting cultivation fallow hotspot map was derived to identify the repetitive patches, in which the state of Arunachal Pradesh topped with 24.9% and Tripura with lowest 3.6%. Field sampling revealed dominance of four invasive species viz., Mikania micrantha, Ageratum houstonianum, Chromolaena odorata and Ageratina adenophora. We provided an insight into shifting cultivation fallow dynamics and vegetation composition in less than 3 year old shifting cultivation fallow lands. The study using remote sensing approach revealed that the fragile ecosystems of NEI are still facing the threat from shifting cultivation, though the trend has started declining. The generated database can be regularly updated in future using recent Sentinel-2 data with higher spatial and temporal resolution that would enhance the quality of land use management plans.

Influence of altitude and slope-aspect on diversity, regeneration and structure of some moist temperate forests of Garhwal Himalaya

Abstract: The climate and altitude play an important role in composition and distribution of Himalayan vegetation Hence this study was aimed to understand the influence of altitude and slope aspect on diversity, regeneration, and structure of some temperate forests of Garhwal Himalaya The maximum mean tree density (627 ± 2704 trees ha−1) was recorded on southwest facing aspect for Rhododendron arboreum-Quercus semecarpifolia association whereas, minimum (555 ± 4311 trees ha−1) on northwest aspect for Quercus semecarpifolia-Abies spectabilis association However, highest mean total basal cover value (9984 ± 109 m2 ha−1) was found on northwest aspect and lowest (7915 ± 129 m2 ha−1) on southeast facing aspect for Q semecarpifolia-A spectabilis association The greater mean Shannon Index values (ie, trees, 140 ± 005; shrubs, 167 ± 005 and herbs, 248 ± 005) were recorded for R arboreum-Q semecarpifolia (CTI), Q semecarpifolia-A pindrow (CTII) and Q semecarpifolia-A spectabilis (CTIII), respectively, whereas, lower value (trees, 059 ± 017) for Q semecarpifolia-A spectabilis (CTIV), shrubs (144 ± 016) and herbs (20 ± 012) for R arboreum-Q semecarpifolia association The tree species like Quercus semecarpifolia, Rhododendron arboreum, Abies spectabilis were found widely distributed in the study area The regeneration study revealed that southwest facing aspect community vegetation experienced additional threat of extinction by representing 2667% species as not regenerating Overall a reverse ‘J’ shaped structure was obtained for all studied communities representing higher densities on lower dbh classes while, The Q semecarpifolia-A spectabilis (CTIII) exhibited maximum total basal cover value on higher dbh classes (ie, 50–70 cm) Henceforth, it could be concluded that the forest community growing between 2800–3400 m asl was comparatively mature and old growth, and could be recommended for conservation purposes

Culturable microbial diversity in the rhizosphere of different biotypes under variable salinity

Abstract: The microbial diversity in the rhizosphere of different biotypes is influenced by different factors like plant species, root exudates and soil environment Culturable microbial diversity in the rhizosphere of six biotypes (Chenopodium murale (CM), Spergula arvensis (SA), Launaea nudicaulis (LN), Brassica juncea (BJ), Phalaris minor (PM) and Triticum aestivum (TA)) growing in variable saline environment (ECe 80 dS m−1) was assessed and compared with the diversity of bulk soils (BS) of same environments The significantly (P < 00001) highest bacterial and actinomycetes population were found in the rhizosphere of BJ whereas SA possessed higher fungal population Phosphorus and zinc solubilizing bacteria was also found highest in BJ and TA rhizosphere, respectively High saline soils had greater endospore forming bacterial population The TA (088) and LN (087) rhizospheres showed significantly greater Shannon–Weiner diversity index compared to bulk soils (045–061) Pielou’s index of evenness of different samples ranged from 013 to 043 Discriminant function analysis revealed that rhizospheres of SA, CM and TA were clearly distinct The rhizospheric soil of PM and BJ were similar to each other but clearly distinct from others The observed separation of different biotypes was regulated by dimorphic fungi, nitrogen fixing bacteria, Pseudomonas, and fungi Thus, our study clearly suggests that culturable microbial populations are influenced by different biotypes and salinity levels

Tree diversity and community composition in sacred forests are superior than the other community forests in a human-dominated landscape of Meghalaya

Abstract: Tree diversity and community composition in six sacred forests (SF) of Meghalaya were compared with those of six adjacent community forests (CF) to understand how protection provided to sacred forests by the communities impacts their diversity and community characteristics. The SFs harboured a greater number of tree species (187) compared to the CFs (56). Tree density in the SFs ranged from 750 trees ha−1 (MKSF) to 1470 trees ha−1 (MTSF) while in CFs, it was 875 trees ha−1 (ILCF) to 1236 trees ha1 (NBCF). Among the SFs, the highest basal area was recorded in MNSF (56.89 m2 ha−1) and least in NBSF (40.75 m2 ha−1), while among the CFs tree basal area ranged from 23.7 m2 ha−1 in MKCF to 36.0 m2 ha−1 in MNCF. The canopy cover in SFs ranged from 73.3 to 86.2% while in CFs it ranged from 54.3 to 70.8%. Species rank abundance distribution (RAD) curve or dominance-diversity curve showed high equitability and low dominance in all the six SFs while the RAD curve showed high dominance and low equitability in all the six CFs. The dominance-diversity curve in the SFs followed a log-normal distribution whereas the CFs exhibited a broken stick distribution pattern. Among the CFs, Pinus kesiya was the dominant tree species in five out of six study sites. The dominant species were different for different SFs, which were Microtropis discolour (ILSF), Citrus latipes (MNSF), Castanopsis tribuloides (MTSF), Castanopsis armata (NBSF), Myrica esculenta (NKSF) and Taxus wallichiana (MKSF). SFs were characterized by high diversity and low dominance as seen in old-growth forests. Shannon’s diversity index (H′) in the SFs ranged from 2.06 to 4.28 indicating high tree diversity, while in CFs it was 0.76–2.61 reflecting relatively lower diversity. Simpson’s dominance index for trees was higher in CFs (0.09–0.73) than the SFs (0.02–0.26).

Habitat suitability model of endangered Latidens salimalii and the probable consequences of global warming

Abstract: Salim Ali's fruit bat, Latidens salimalii, is a monotypic endangered fruit bat endemic to Western Ghats (WG) with an ambiguous distribution. The distribution range, habitat suitability, and biology of this species are still uncertain. Endemic species inhabiting the high elevation of WG like L. salimalii are threatened due to climatic change and seeks urgent management interventions. Hence, we developed a habitat suitability model for L. salimalii using MaxEnt in the current climate condition and projected their distribution for three Representation Concentration Pathway (RCP 4.5, 6.0, and 8.5) climate scenarios of the 2070 time frame. The results show that 9531 km2of habitat in WG is suitable for L. salimalii at present, while all the future scenarios estimates propose complete loss of highly suitable habitat. The significant factors influencing the distribution of L. salimalii are the precipitation of the driest month, tree density, rain in the coldest quarter, canopy height, and altitude. The study pioneers in predicting the suitable habitat and emphasis the need to develop strategies for the long-term conservation of endangered L. salimalii in WG under global warming scenarios.

Tree diversity and carbon stock in a subtropical broadleaved forest are greater than a subtropical pine forest occurring in similar elevation of Meghalaya, north-eastern India

Abstract: Studies on relationship between tree diversity and carbon stock has not been consistent. The present study was undertaken to quantify and compare the plant diversity and carbon stock in a subtropical broadleaved and a subtropical pine forest of Meghalaya, northeast India. Biomass-based carbon estimation was undertaken in two subtropical broadleaved forest stands viz., Mawnai (MBF) and Nongkrem (NBF) and adjacent Pinus kesiya dominated forest stands (MPF and NPF), occurring in similar topography, climatic conditions and soil type. The aboveground and belowground tree biomass was estimated using existing allometric models. Carbon was estimated as 47.4% of the total biomass. Tree species richness was greater in the subtropical broadleaved forest stands at MBF and NBF (117 and 21 species) than in the adjacent pine forests, MPF and NPF (15 and 16 species). The density values were 1294 and 1127 individuals ha−1 in the broadleaved forest stands, and 894 and 1032 individuals ha−1 in the adjacent pine forest stands, respectively. The broadleaved forest stands, MBF and NBF had tree biomass carbon stock of 140.4 Mg C ha−1 and 133.6 Mg C ha−1, respectively, which were significantly greater (F = 26.6; P 66 cm) to the total biomass carbon was greatest in MBF, while the lower diameter trees belonging to 5–15 cm and 16–25 cm were the major contributors to the total biomass carbon in the pine dominated stands.

Carbon stock assessment and its relation with tree biodiversity in Tropical Moist Deciduous Forest of Similipal Biosphere Reserve, Odisha, India

Abstract: Spatial understanding of biomass and carbon stock in tropical moist deciduous forests is crucial in assessment of global carbon budget. The present study was aimed to assess the above ground and below ground carbon stock and its relation with tree diversity parameters in two tropical moist deciduous forest sites, namely: Xylia dominated forest (XDF) and Sal dominated forest (SDF) of Similipal Biosphere Reserve (SBR), Odisha, India. A total of seventy-two tree species ≥ 5 cm diameter at breast height (dbh) were recorded, belonging to 62 genera and 27 families. Estimated average above-ground biomass carbon and soil organic carbon were 180.05 Mg C ha−1, 55.4 Mg C ha−1 and 209.3 Mg C ha−1, 61.8 Mg C ha−1 in XDF and SDF of SBR, respectively. Shorea robusta Gaertn. was the most carbon accumulating species of both the forests contributing about 21.5% of biomass carbon in XDF and 47.8% biomass carbon in SDF. Maximum carbon allocation was in above-ground biomass pool (69.04%) followed by soil organic carbon (20.9%) and below-ground biomass/root (10.1%). The correlation study revealed that above-ground biomass had strong positive correlation with basal area and Importance Value Index of tree species indicating importance of dominant species in carbon storage. Therefore, the dominant tree species such as S. robusta Gaertn., Xylia xylocarpa (Roxb.) Taub., Terminalia tomentosa Wight & Arn., Schleichera oleosa Lour.) Merr. etc. is suggested for proper conservation and management to maintain the carbon stock of SBR. The results emphasized the importance of tropical moist deciduous forests in potential carbon storage and conservation of biodiversity in forest ecosystem of India. Further, the information will supplement to the global deficit of carbon stock data of moist deciduous forest and has implications in carbon model projections and management both nationally and globally.

Soil thickness and affecting factors in forestland in a karst basin in Southwest China

Abstract: Soil erosion is a process of land degradation worldwide, and it is a serious problem in karst mountainous areas To clarify the leading factors contributing to soil erosion in forestland in a karst mountainous basin in Southwest China, the environmental characteristics of 424 designated sites in the Houzhai River basin were investigated and analysed Artificial neural networks (ANNs) were used to predict soil erosion based on environmental factors The results indicated that soils in karst mountainous areas are highly heterogeneous (shallow and discontinuous), and soil thickness ranged from 7 to 100 cm with a mean value of 3105 cm Correlation analysis revealed that soil gravel, slope gradient, soil organic matter and vegetation were the basic driving forces for soil erosion in forestland in this karst mountainous area In addition, we found that ANNs could be employed for predicting soil thickness (the correlation coefficients between observed values (validation data) and predicted values ranged from 073 to 096, with a mean value of 085) The normalized importance analysis indicated that altitude (013), soil gravel (013), soil organic matter (012), rock outcrop (012), slope gradient (012) and soil bulk density (011) should be prior considered for soil erosion prediction Our study suggested that enhance vegetation coverage could be the effective ways to the aspect of prevention and controlling of soil erosion in Karst areas

Ecosystem carbon stocks in different aged tea agroforestry systems: implications for regional ecosystem management

Abstract: Tea (Camellia sinensis) is often grown under a canopy of trees forming a distinctive agroforestry system covering an estimated area of 3.94 million ha of land globally. Although, tea is a major commercial crop in many countries in tropical and sub-tropical regions, including China, India and Sri Lanka, tea agroforestry systems (TAFS) have remained little studied for their role in carbon management and climate change adaptation/mitigation actions. We, therefore, undertook a detailed study on the storage of organic carbon in above- and below-ground vegetation and soil under age chronosequence of TAFS in North East India. The specific aim of this study was to quantify variations in soil physical and chemical properties, carbon storage in shade trees and tea bushes, and ecosystem carbon stocks under the chronosequence of TAFS. This study has established significant variations in soil properties and carbon storage in different aged TAFS. One of the salient findings is the decrease in soil bulk density and increase in water holding capacity with the age of TAFS in the 0–50 cm depth. The total vegetation C stock (shade trees + tea bushes + litter biomass) increased with increase in the age of TAFS, and the increase was as high as 25% in > 20 years compared to younger (< 10 years old) TAFS. The ecosystem C stock estimated at 162–187 Mg ha−1 was higher than many temperate and tropical agroforestry systems suggesting TAFS may effectively contribute to Clean Development Mechanisms CDM/REDD+ mechanisms of the United Nations Framework Convention on Climate Change (UNFCCC) once standard guidelines for market mechanisms are in place.

Mapping and dynamic analysis of mangrove forest during 2009–2019 using landsat–5 and sentinel–2 satellite data along Odisha Coast

Abstract: Mangrove forests in India are situated along the tidal sea edge of the Arabian Sea and Bay of Bengal which is under threat from both natural and human-induced land-use changes. The multi-temporal satellite data and image processing techniques are usually employed to monitor changes in vegetation dynamics. In this study, the decadal changes of mangrove forests were accomplished along the Odisha coast, India using the Landsat–5 and Sentinel–2A satellite data for 2009 and 2019, respectively. The satellite data were obtained and processed in the Google Earth Engine (GEE) platform. This study aims to derive the spatial extent of mangrove using the high-resolution satellite data and support vector machine (SVM) classifier. The result reveals that the total mangrove extent increased from 222.43 km2 (2009) to 252.47 km2 (2019) which indicates an increase in area by 30.04 km2 (or 13.5%) during the last one decade. The highest increase in mangrove area was in Hatamudia Reserve Forest (15.54 km2) and coastal belt of Bhadrak (9.46 km2) followed by Bhitarkanika National Park in Kendrapara (3.05 km2), Baranaula and Akumi River estuary in Jagatsinghpur (1.12 km2), and Subarnarekha River intertidal zone in Baleshwar (0.87 km2). A significant increase in mangrove forests occurred due to plantation, awareness, restoration, and coastal zone management plan. This study demonstrates the potential of high-resolution satellite data to produce an accurate map in monitoring changes in mangrove forests at a decadal time-scale by using the GEE platform which can help in planning conservation strategies and priorities.

Density of leopard in a moist-temperate forest of western Himalaya, India

Abstract: Widespread conversion of the biodiversity rich habitats into land for cultivation and human habitation has resulted in extensive habitat loss for wildlife including leopard. In order to prioritize investments and assess conservation intervention and effectiveness reliable estimates of population density are required. We carried out camera-trapping and line-transect surveys to estimate the predator and prey densities in moist-temperate forest of Dachigam National Park, north-western Himalaya. Density estimate for leopard (Panthera pardus) obtained from programme CAPTURE was 2.8 ± SE 1.18/100 km2 and the SECR density obtained from software SPACECAP was 0.744 ± SE 0.18/100 km2. Density estimate obtained using software DISTANCE for the two principal prey species was 5.11 ± 0.51/km2 and 16.32 ± 1.87/km2 for hangul (Cervus hanglu ssp. hanglu) and langur (Semnopithecus ajax), respectively. The leopard density estimates, which are a first record from the study area, turned out to be the lowest in the country. The low densities of prey represent an alarming status of the species as well as of forest ecosystems of the study area. Our baseline estimates for the leopard and prey species will help future research, conservation and management strategies.

Predicting land use and land cover scenario in Indian national river basin: the Ganga

Abstract: A reliable LULC model aims at predicting the spatial distribution of specific LULC classes for a later year by utilizing the trends from previous years thereby helps in appropriate LULC planning. The Ganga River Basin (GRB) has undergone significant LULC changes during past decades. The changes in LULC pattern was investigated for 1975 and 2010 to have better understanding of the conversion process and thereby predicting the future trend for 2045 using Dyna-CLUE (Conversion of Land-Use and its Effects) model. Four types of data were fed into the model i.e., (a) spatial policies and restrictions; (b) LULC type specific conversion settings; (c) LULC requirements (demands) and (d) location characteristics. The possible and impossible conversions among LULC classes were dealt with through Restriction and No Restriction area. The land conversion allocation was determined by establishing preference between LULC classes and the driving factors using binary logistic regression. Relative Operating Characteristic curves provided an overall value of 0.86 implying acceptability of regression results. The simulated result (with ‘no restriction’ area criteria) showed 578,296 km2 agriculture area in 2010 and 579,235 km2 for 2045, wherein 575,874 km2 (99.58%) of agriculture area could remain unchanged during 2010–2045; while with the restricted area, agriculture area of 577,675 km2 in 2010 and 578,516 km2 for 2045; whereas 576,242 km2 (99.75%) of agriculture area may remain unchanged during 2010–2045. Biophysical drivers namely altitude, slope, aspect, soil types, precipitation and temperature, emerged as major controlling factors for LULC change in GRB. Logistic regression analysis showed that population density is positively related with agriculture and expansion of settlements.

Road as a major driver for potential distribution of the invasive giant African land snail in Nepal

Abstract: Biodiversity loss is increasing globally due to many anthropogenic factors including invasive species. Among the invasive species, the giant African land snail which is World’s worst invasive species is threatening the native species and become major pest for economy loss. Although the impact of snail is widespread in Nepal, we have little knowledge on their distribution and spreading factors. Using species distribution modeling, we found more than 50% of their potential area at Tarai region followed by Siwalik (29%) and 20% in mid-hill regions. The findings indicated that the species has potential for spreading to the high-mountain areas due to road and transportation. Inspite of past history of the species occurrences, the current distribution expanded across the entire country in the low lands and mountain regions. Therefore, we recommend government to prevent the potential spreading of the giant African land snail in Nepal by developing and devising policy measures to control the species in and around the roadsides. In addition, we suggest the government for proper cleaning of vehicles and transporting materials before transportation or area specific quarantine through public awareness.

Temporal changes in rhizosphere biological soil quality indicators of wheat in response to nitrogen and straw incorporation

Abstract: Soil health and sustainability of rice-wheat cropping system (RWCS) in the Indo-Gangetic plains (IGP) in South Asia are possibly adversely influenced due to in-situ burning of large quantities of rice residues. Instead of burning, it is increasingly being advocated to incorporate the crop residues into the soil. In a field experiment, effects of four nitrogen (N) levels (0, 90, 120 and 150 kg N ha− 1) as main-plots and four levels of rice straw (RS) incorporation (to a depth of 0.10–0.15 m) (0, 5, 7.5 and 10 t ha− 1) as sub-plots in split plot design were studied on soil enzymatic activities at two stages i.e. maximum tillering (MT) and flowering (FL) of wheat, and crop yield after 7 years. Activities of dehydrogenase, fluorescein diacetate, alkaline phosphatase, acid phosphatase, phytase, urease, l-asparaginase, cellulase, xylanase, β-glucosidase, peroxidase and phenol oxidase enzymes and grain yield of wheat in the treatment receiving 120 kg N ha− 1 and 10 t ha− 1 RS incorporation were significantly higher than in the control (without N and RS incorporation). The enzyme activities except peroxidase and phenol oxidase were dominated in rhizosphere than in the bulk soil, and at MT rather than at FL stage. Principal component analysis revealed that l-asparaginase, and phenol oxidase activities can be used as the most sensitive and reliable indicators for assessing soil quality under RWCS when rice residues are incorporated into the soil.

Regional dynamics in distribution of Prosopis juliflora under predicted climate change in Africa

Abstract: Climate change is considered to be one of a principle reason for spread of invasive alien species. Thus, it is essential to examine potential invasion dynamics of Prosopis juliflora at continental scale under climate change scenario to better guide management of the invasive species. A consensus model derived from five models were used to examine the current and future (2050 and 2070) climatic suitability for P. juliflora under two climate scenarios (RCP4.5 and RCP8.5) in Africa. The mean area under the receiver operating characteristic curve (AUC) and the threshold-dependent true skill statistic (TSS) value of the models were 0.85 and 0.94, respectively, this put the models in the “very good” category. Results showed that temperature related variables were the main determinant factor accounting for 65.7% of the distribution of P. juliflora. Under current climatic scenario, 75.6% of the continent was unsuitable for P. juliflora establishment and invasion while 5.6% was highly suitable. The total suitable areas for P. juliflora under RCP4.5 and RCP8.5 would increase by 2050 and 2070 compared to the current conditions. Meanwhile, a decrease in total unsuitable areas would be expected by 2050 and 2070 under both RCP4.5 and RCP8.5. This study has revealed that; the rates of P. juliflora invasion will expand further inland across Africa as climatic conditions become favourable. Negative environmental and economic impacts caused by P. juliflora will be high if management measures are not earnestly taken. We recommend for a cross-border continental wide effort towards combating P. juliflora expansion to new areas, especially in countries predicted as frontiers of potential expansion.

India’s contribution to mitigating the impacts of climate change through vegetation management

Abstract: The changes in natural ecosystems provide opportunity to increase vegetation carbon sink capacity and thereby contribute to mitigation of climate change impacts. The Indian tropics and the large ecological variation within the country afford the advantage of diverse niches and offer opportunities to reveal the role of biotic factors at different levels of organization from populations to ecosystems. The last 4 decades of research and development in the Indian space science community has been primarily application driven in response to the government space programme for national development. The expenditure in R&D over next 5 year suggest that scientific research is higher on the country's agenda. The Indo-UK Terrestrial Carbon Group (IUTCG) comprising both Indian and UK scientists, funded jointly by the Department of Science and Technology, India and the Department of Business, Innovation and Skills organised a workshop to explore ways in which Earth observation data can be effectively utilised in mitigating the impacts of climate change through vegetation management. Effective integration of field observations, collected through various monitoring networks, and satellite sensor data has been proposed to provide country-wide monitoring.

Impact of alien species on species composition, floristic and functional diversity of aquatic and terrestrial ecosystems

Abstract: Biotic homogenization is a major component of current biodiversity crisis involving increase in floristic, functional and genetic similarity of biotas resulting from species invasions and extirpations. Since habitat type is a good predictor of success of biological invasion at local scale, we studied distribution and abundance of native and alien plant species in eight habitat types namely lakes, wetlands, riparian, roadsides, orchards, grasslands, scrubs, and forests (06 sites each giving a total of 48 sites). For estimating taxonomic homogenization index, we calculated Jaccard’s similarity index separately for native, alien and alien + native species. We also calculated functional α, β, and γ diversity for three functional traits in three different ways i.e. with all species included, with only native species included and with only alien species included. We observed that habitats differ with respect to functional and floristic diversity. Aquatic habitats (species poor) were found to be more homogenous (average βA = 0.58) than terrestrial habitats (average βA = 0.68) with man-managed habitats (orchards) being taxonomically (average βA = 0.59) and functionally (FβA = 0.04) most homogenous among terrestrial habitats. Present study revealed that traits of alien plant species play an important role in determining the homogenization potential as invasives (in comparison to naturalized and casuals), perennials (in comparison to annual/biennials), herbaceous (in comparison to shrubs/sub-shrubs/lianas and trees) and submerged plants (in comparison to free floating, rooted floating and emergents) were found more homogenizing. These observations are crucial in understanding the homogenizing effects of alien species and in particular the underlying impact of taxonomic homogenization on functional stability of ecosystems.

Tree-ring climate response of two Larix species from the central Nepal Himalaya

Abstract: Changes in the global temperature and precipitation regime have been significantly driving species responses, notably in sensitive areas such as the Himalayas By conducting a study at two high altitude (3200–4100 m) valleys (Langtang and Tsum) situated in the central part of the Nepal Himalayas, we presented tree-ring width site chronologies for two Larix species (Larix griffithii and L himalaica) for the first time The longest chronology spans from 1771 to 2015 AD and showed a recent decline in the growth of Larix species in both sites, controlled mainly by drought Tree growth showed a negative response to temperature and a positive response to precipitation, indicating that moisture stress is limiting the growth of the species Based on the Larix ring width chronology statistics and climate response results, these species have good potential for past climate reconstruction such as temperature, rainfall or drought indices Also, the study revealed that the Himalayan endemic Larix species investigated are promising for tree-ring based multi-aspect environmental change studies in the future

Patterns in distribution of butterfly assemblages at different habitats of Corbett Tiger Reserve, Northern India

Abstract: Corbett Tiger Reserve (CTR) located in state Uttarakhand is the first protected area established for in-situ conservation of biodiversity in India. Despite its national importance, there exists lacunae in knowledge on butterflies, important from the viewpoints of effective planning and implementation of conservation actions in the CTR. Using standardized methods, the present study conducted between 2013 to 2014 was aimed to record butterfly species composition and distribution in different sampling regimes of the CTR in relation to habitat types and disturbances. Study revealed a total of 2621 individual butterflies of 56 species under 5 families. Among them, 24 species belong to the Nymphalidae family, 14 species to the Pieridae, 9 species to the Lycaenidae, 5 species to the Papilionidae and 4 species to the Hesperiidae. 50% of the total species were recorded as ubiquitous and 30 species are new records to the CTR. Species such as Catopsilia pomona (Fabricius), Papilio polytes (Cramer), Eurema hecabe (Linnaeus), Catopsilia pyranthe (Linnaeus) were most abundant and Athyma zeroca (Moore), Sarangesa purendra (Moore), Cyrestis thyodamas (Boisduval), Polyura agraria (Swinhoe) were least abundant species. Variations in the calculated diversity indices across the seasons were observed; wherein, summer season exhibited maximum value for Shannon-Diversity index, followed by late monsoon and early winter. Lowest diversity of butterflies was observed during the periods of late winter. Presence of seven species under the Indian Wildlife Protection Act and five species as rare, substantiate the importance of pristine conditions prevailing in the protected landscape of the reserve. Ongoing tourism activities and habitat alterations threatening butterfly diversity and ecological integrity of the CTR, were also discussed.

Modelling of evapotranspiration using land surface energy balance and thermal infrared remote sensing

Abstract: Accurate estimation of crop evapotranspiration (ET) is a key factor in crop water scheduling. The objective of this study was to estimate ET from the high-resolution satellite remote sensing data with integration of in situ observation. The surface energy balance model, Mapping Evapotranspiration with Internalized Calibration (METRIC) was utilised in this study for its simplicity, advantages, and effectiveness. It is a one-source model, which calculates the net radiation, soil heat flux, and sensible heat flux at every pixel level, and estimates the latent heat flux as the residual term in that energy budget equation. Intermediate steps like calculation of NDVI, surface temperature, and albedo served as important input parameters for ET estimate. Landat-8 satellite images were used to compute the ET in paddy field near CRRI, Cuttack, Odisha state in eastern India. Results indicated that the METRIC algorithm provided reasonably good ET over the study area with marginal overestimation in comparison to field observation by eddy covariance data. The satellite-based ET estimates represented in spatial scale has potential in improving irrigation scheduling and precise water resource management at local scales.

Molecular and morphological evidence for the identity of the giant mottled eel, Anguilla marmorata in Southeast Asia

Abstract: Tropical anguillid eels account for two-thirds of all species in the genus Anguilla, however information on the species diversity, biogeography, and life histories is very limited. The anguillid eels found in Southeast Asian waters, i.e. Malaysia, Thailand and Vietnam were identified using molecular genetic analysis after morphological observation. This is the first record of the occurrence of A. marmorata in Thailand and Vietnam that was confirmed by both morphological and molecular genetic analyses. The molecular phylogenetic tree and the haplotype network of A. marmorata in Malaysia, Thailand and Vietnam suggested that the eel might be transported from the western North Pacific spawning area. We also propose possible dispersion and migration of A. marmorata into Southeast Asian waters.

Vegetation dry matter dynamics along treeline ecotone in Western Himalaya, India

Abstract: 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.

Tree species composition and diversity in abandoned Jhum lands of Mizoram, North East India

Abstract: Shifting agriculture system (locally known as Jhum) is the main driver of deforestation and forest degradation in north eastern region. This system has been extensively practiced to sustain the livelihood in rural areas of Mizoram which possesses serious threats to forest ecosystem and soil fertility. The course of vegetation development in secondary forest in abandoned fallow is a major concern to understand the process of succession in different fallow length. This study was undertaken in Aizawl and Mamit districts, Mizoram with the objectives to determine the tree species diversity, richness and abundance in different fallow periods. Fallow ages of 2–5 years (F5), 6–10 years (F10), 11–20 years (F20) and 21–30 years (F30) were selected with a total number of 37 sites and two circular plots of 12.6 m were laid in each site to carry out extensive enumeration and analysis of tree species. A total number of 91 tree species and 38 families were recorded. The number of trees increased by 47% from F5 to F10 but the same was decreased by 35% from F10 to F30. Ecological indices indicate high diversity and species richness in F10 and F30 compared to F5 and F20. The basal area significantly increased with the length of fallow period. The average girth at breast height (GBH) in F5 was 30 cm but in F30, the GBH increased to 130 cm. The dominant species changed as fallow period increased e.g. F5 was dominated by Castanopsis tribuloides, F10—Rhus chinensis, F20—Macaranga denticulata and F30—Albizia chinensis. The changes in dominant species with respect to fallow ages in the present study could be due to large anthropogenic disturbance on the pioneer species as well as greater establishment ability of the climax species in relation to its environment, altitude and soil condition.

Geo-spatial approach for land-use and land-cover changes and deforestation mapping: a case study of Ankasha Guagusa, Northwestern, Ethiopia

Abstract: Deforestation is the replacement of forest by other land-use. Land-use patterns are changing fast in worldwide in relation to the human population growth and agricultural land expansion. The study deals with the status and trends of land-use and land-cover (LULC) dynamics and identification of deforestation risk zones Ankasha Guagusa, northwestern, Ethiopia following in the recent advancement in geospatial approach. The temporal Landsat satellite data from 1985 to 2018 was used for the analysis. Supervised classification approach with maximum likelihood algorithm was adopted for the classification and generation of land-use and land-cover maps for the chosen time periods. Results reveal that there have been substantial changes in the LULC during the selected periods. During the period 1985–1996 showed increased the cropland, bare-land and built-up with 835 ha (1.78%), 186.54 ha (0.4%) and 112. ha (0.24%), respectively. In the second period (1996–2006) forest land, built-up and cropland increased with 1094 ha (2.33%), 346.78 ha (0.74%) and 2185.7 ha (4.65%), respectively. This implies that the forest cover change had decreased by 1119.78 ha (2.38) in the first period and increased in the second and third period with 1094.04 ha (2.33%) and 772.91 ha (1.64%), respectively. It was raveled that forest cover though remained relatively stable around western part of the study area. Identification of deforestation risk zone to examine five factors criteria was selected such as infrastructure, topographic and socio-economic behavior of the area. These are slope, proximity to road, population density, proximity to river and proximity to town. Each criterion was evaluated with the aid of AHP and mapped by GIS. The degree of deforestation risk was categorized as extreme, high, moderate and low suitability areas, which represented 2%, 40.27%, 56.65% and 1.04%, of the study area, respectively. Therefore, sustainable forest management system is necessity to protect, conserve and rehabilitate the remaining forest.

Nutrient status in herbaceous layer of riparian forests in Southwestern, Nigeria

Abstract: The nutrients status of herbaceous species in riparian zones of Africa is often neglected, with focus mainly on woody species, despite the crucial role played in the functioning of the forest ecosystems. The herbaceous species in riparian forest ecosystems contributes significantly to litters accumulated in the forest floor more invariably playing a significant role in nutrients return to the soil more than woody species. Herbaceous species were collected from five (5), 1 m × 1 m quadrats randomly laid within each sampling plot. The collected samples from the quadrats were pooled together from each sites and oven dried at 80 °C for 72 h and weighed to constant weight. The ground samples were analysed for nutrients. The increasing order of nutrient elements concentration in the herbs across sites were: P < Na < Mg < K < N < Ca < C. The uptake of nutrients by herbaceous species is strongly influenced by site uniformity, level of disturbances, the nutrient concentrations of these elements resident in the soil of the riparian forest ecosystems.

Elucidating space based observations of solar induced chlorophyll fluorescence over terrestrial vegetation of India

Abstract: Remotely sensed plant fluorescence signals have the potential to facilitate a better understanding of vegetation photosynthetic dynamics. Space based observations of solar-induced chlorophyll fluorescence (SIF) provides an alternative non-invasive approach to investigate gross primary production (GPP), a key element of ecological research. Orbiting carbon observatory (OCO-2) is providing continuous global measurements of SIF at 757 nm and 771 nm wavelengths with nadir and glint mode observations. Using one of the three spectrometer instruments, measurements of SIF complements OCO-2’s Carbon dioxide data with information on when and where plants are drawing carbon from the atmosphere. Here, we present spatio-temporal patterns of space borne observations of SIF and its correlation with GPP and vegetation indices over diverse terrestrial vegetation of India. The results indicate a spatial variability in SIF ranging from 0.001 to 0.6 (± 0.16) Wm−2 µm−1 sr−1 and 0.001 to 0.7 (± 0.2) Wm−2 µm−1 sr−1 in nadir and glint modes, respectively. OCO-2 derived SIF at finer scale shows a similar trend with MODIS derived GPP during September–October–November and June–July–August seasons. A linear correlation of satellite derived SIF with GPP (Pearson’s coefficient, r = 0.84), EVI (r = 0.72) and NDVI (r = 0.63) at 757 nm for 0.05° × 0.05° grid over terrestrial India is reported, besides seasonal variations. Amongst the diverse vegetation types, SIF and GPP are well correlated over Evergreen broadleaf forests. The study provides new insights and useful inputs to GPP modelling and improved understanding of terrestrial carbon cycle research in India.