Species diversity of woody vegetation along altitudinal gradient of the Western Himalayas

From forest floor to tree top: Partitioning of biomass and carbon stock in multiple strata of forest vegetation in Western Himalaya

The foremost role of forest vegetation in storing biomass and carbon (C) stock constitutes one of the main nature-based solutions to mitigate climate change. In this study, we aimed to quantify biomass and C stock partitioning in multiple vegetation strata (tree, shrub, herb, and ground floor layers) of major forest types in Jammu and Kashmir, Western Himalaya, India. We used a stratified random cluster sampling strategy to collect field data in 96 forest stands of 12 forest types (altitudinal range: 350 to 3450 m) in the study region. We evaluated the degree to which the carbon stock of the entire ecosystem was dependent on the multiple vegetation strata using the Pearson method. Across all the forest types, the average total ecosystem-level biomass was estimated to be 181.95 Mgha^-1 (range: 60.64-528.98). Forest strata-wise, the maximum biomass of 172.92 Mgha^-1 (range: 50.64-514.97) was found in the tree vegetation, followed by 5.58 Mgha^-1 (range: 2.59-8.93) in understory vegetation (shrubs and herbaceous), and 3.44 Mgha^-1 (range: 0.97 and 9.14) in the forest floor. The total ecosystem-level biomass showed a peak at mid-elevation coniferous forest types, whereas the lowest was observed in low-elevation broad leaved forest types. At the ecosystem-level, on average, the understory contributed 3% and the forest floor 2% to the total C stock across the forest types. The shrub layer contributed up to 80% of total understory C, with the herbaceous layer accounting for the remaining 20%. The ordination analysis clearly shows that anthropogenic and environmental variables significantly (p ≤ 0.002) influence the forest types' C stock in the region. Our findings have significant implications for conserving natural forest ecosystems and restoring degraded forest  landscapes in this Himalayan region, which in turn can lead to better carbon sequestration and climate mitigation outcomes.

Soil bacterial community changes along elevation gradients in karst graben basin of Yunnan-Kweichow Plateau

Elevation gradients could provide natural experiments to examine geomorphological influences on biota ecology and evolution, however little is known about microbial community structures with soil depths along altitudinal gradients in karst graben basin of Yunnan-Kweichow Plateau. Here, bulk soil in A layer (0 ~ 10 cm) and B layer (10 ~ 20 cm) from two transect Mounts were analyzed by using high-throughput sequencing coupled with physicochemical analysis. It was found that the top five phyla in A layer were Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, and Verrucomicrobia, and the top five phyla in B layer were Proteobacteria, Acidobacteria, Actinobacteria, Verrucomicrobia, and Chloroflexi in a near-neutral environment. Edaphic parameters were different in two layers along altitudinal gradients. Besides that, soil microbial community compositions varied along altitudinal gradient, and soil organic carbon (SOC) and total nitrogen (TN) increased monotonically with increasing elevation. It was further observed that Shannon indexes with increasing altitudes in two transect Mounts decreased monotonically with significant difference (p = 0.001), however beta diversity followed U-trend with significant difference (p = 0.001). The low proportions of unique operational taxonomic units (OTUs) appeared at high altitude areas which impact the widely accepted elevation Rapoport's rules. The dominant Bradyrhizobium (alphaproteobacterial OTU 1) identified at high altitudes in two layers constitutes the important group of free-living diazotrophs and could bring fixed N into soils, which simultaneously enhances SOC and TN accumulation at high altitudes (p < 0.01). Due to different responses of bacterial community to environmental changes varying with soil depths, altitudinal gradients exerted negative effects on soil bacterial communities via soil physical properties and positive effects on soil bacterial diversities via soil chemical properties in A layer, however the results in B layer were opposite. Overall, our study is the first attempt to bring a deeper understanding of soil microbial structure patterns along altitudinal gradients at karst graben basin areas.

Influence of Aspect and Elevational Gradient on Vegetation Pattern, Tree Characteristics and Ecosystem Carbon Density in Northwestern Himalayas

Himalayan forest has been threatened by rapid anthropogenic activities, resulting in the loss of forest diversity and climate change. The present study was carried out on four aspects (northern, southern, western and eastern), at three different altitudinal ranges, namely, 1000–1300 m above sea level (m a.s.l.), 1300–1600 m a.s.l. and 1600–1900 m a.s.l., and at three diverse mountain ranges (Kalaghat, Barog and Nangali) of sub-temperate forest ecosystems of the mid Himalayan ranges, to elucidate their influence on vegetation, tree characteristics and ecosystem carbon density. The results revealed that Pinus roxburghii is the most dominant forest community of the mid Himalaya’s forest, irrespective of altitudinal gradient and slope. The south-facing slopes are occupied by the xerophytic tree species frequently found in the lower Shiwalik P. roxburghii forest, whereas the north-facing ones are dominated by mesophyllic species, such as Cedrus deodara and Quercus leucotrichophora, which commonly grows in the northwestern Himalayan temperate forest ecosystem. The maximum stem density (211.00 Nha−1) was found at 1000–1300 m a.s.l., and on the northern aspect (211.00 Nha−1). The maximum stem volume (236.50 m3 ha−1) was observed on the northern aspect at 1000–1300 m a.s.l., whereas the minimum (32.167 m3 ha−1) in the southern aspect at 1300–1600 m a.s.l. The maximum carbon density (149.90 Mg ha−1) was found on the northern aspect and declined with increasing elevation from 123.20 to 74.78 Mg ha−1. Overall, the study establishes that the southern and western aspects are very low in carbon density, whereas the northern aspect represents higher biodiversity as well as carbon and nutrient stocks. Therefore, aspect and altitude should be given due importance for efficient managing of biodiversity and mitigating climate change.

Use of Wild Edible Plants: Can They Meet the Dietary and Nutritional Needs of Indigenous Communities in Central India

Despite significant evidence base on quantifying ecosystem services, the role of biodiversity in supporting such services in diversified landscapes, and how indigenous communities exploit, utilize and manage plant resources in a biocultural regime, remains understudied. This study examines the role of wild edible plants (WEPs) in meeting the food, nutrition and household income of indigenous communities under the biodiversity rich landscape of the Achanakmaar-Amarkantak Biosphere Reserve (AABR—22°15′ to 22°58′ N latitudes and 81°25′ to 82°5′ East longitudes) of Central India. Results revealed remarkable differences among Baiga, Gond, Kol, and Oraon ethnic communities and also location (core, buffer and transition) effect on utilization pattern of wild edibles. A sum total of 172 WEPs comprising 60 vegetables, 70 fruits, seeds and nuts, 23 underground tubers and 19 mushrooms were collected, consumed, and surplus were marketed by the communities. On average, the number of wild edibles collected annually by households were in the following quantities: 40–240 kg leafy vegetables, 125–386 kg flowers, 120–250 kg fruits, 12–125 kg legumes, 24–120 kg tubers, 5–35 kg mushrooms. Among ethnic groups, the Baiga primitive community utilized 70–90% followed by Gonds (58–81%), Kols (52–78%), Oraons (43–79%), and other communities (38–68%) in different zones. WEPs have contributed to 5–24% (Rs 3559- 12,710) of household income, which was highest in the core zone and lowest in the transition zone. It was observed that WEPs were complemented the diets rather than being a substitute for staple foods. They supplied only 3.7–8.3% of energy and 1.1–4.9% protein requirements; however, they significantly supplemented ascorbic acid, thiamine, calcium, and iron by 38.1–73%, 13.7–35.4%, 17.2–29.1%, 2.6–13.5%, respectively. Significantly higher quantities of nutrients were supplemented in the core zone compared to other zones. WEPs were currently underutilized (less intake) especially in buffer and transition zones, complementing the staple foods and partially supplementing the essential macro- and micro-nutrients. However, these have the potential to fulfill the dietary needs and ensure balanced nutrition, if consumed in recommended portions and sizes. The paper discusses policy implications that ensure coherence and coordination of local indigenous communities for conservation and sustainable utilization of WEPs of AABR, Central India.

Carbon Storage of Single Tree and Mixed Tree Dominant Species Stands in a Reserve Forest—Case Study of the Eastern Sub-Himalayan Region of India

In recent decades, carbon (C) management is an important point on the agenda to identify the best viable mitigation strategies for its reduction. The study was conducted at Jaldapara National Park located in the Eastern Himalayan region of India. The study quantified litter production, decomposition, periodic nutrient release, soil fertility status, and soil organic carbon (SOC) of five major forest stands i.e., Tectona grandis (TGDS), Shorea robusta (SRDS), Michelia champaca (MCDS), Lagerstroemia parviflora (LPDS) and miscellaneous stand (MS). A stratified random nested quadrate method was adopted for sample collection. Results reveal that the greatest amount of litter production and decomposition was under MCDS followed by MS, LPDS, SRDS, and the smallest under TGDS. The material annual turnover through litter decomposition in all the stands varies between 96.46% and 99.34%. The content and amount of the available nutrients in litter varied significantly among the stands. Moreover, release of these nutrients was nearly equal to the amount available in the initial litter mass. In general, the magnitude of the total nutrient return was in the same order as the total litter fall and the nutrient availability was more closely related to litter nutrient content and soil organic carbon. The range of pH (4.86–5.16), EC (0.34–0.50), soil moisture (27.01–31.03) and available primary nutrients (N: (0.21–0.26 Mg/ha), P: (0.09–0.12 Mg/ha), K: (0.13–0.14 Mg/ha)) also varied significantly among the stands. Significant positive correlations were observed between SOC, N and K. Both the fertility indices exhibited no definite pattern in the stands but a significant correlation between the two indicates the healthy soil fertility status of the stands. SOC varies significantly under different forest stands, but the greatest content was found under MS. The estimated SOC ranges between 75.9 and 107.7 Mg ha−1 up to 60 cm and is reported to be below the Indian average of 182.94 Mg ha−1. The present study strongly recommends that Tectona grandis, Shorea robusta, Michelia champaca, and Lagerstroemia parviflora should be the important commercial timbers of the Eastern Himalayan region because they may help further to increase the C sink in agricultural and degraded landscapes.

Stand Structure, Biomass and Carbon Storage in Gmelina arborea Plantation at Agricultural Landscape in Foothills of Eastern Himalayas

In the modern era, Gmelina arborea plantations are a hotspot of future research because of their high carbon sequestration potential. The present work was conducted during 2018 to 2020 on a young unmanaged Gmelina farm to understand the ecosystem’s carbon and its dynamics. The study area was categorized into three age classes: ≤5, 5–10, and 10–15 years. In a plantation, Gmelina trees (10%) were randomly selected while other trees (90%) were also taken into the consideration for ecosystem carbon. A stratified random nested quadrate sampling method was adopted for analyzing other vegetation forms under study. Overall, 51 individual species in the studied Gmelina farm were found which includes 23 tree species, 7 shrub species, 16 herbs, 2 climbers, and 3 species of ferns. The estimated quantitative vegetation parameters and diversity indices indicate that the plant assemblages were heterogeneous with native diverse species evenly distributed with fairly higher densities, frequencies, and abundance. Herbs were the most important species followed by shrubs and trees. Consequently, with the increasing age of plantation, the richness of plant species increased. Soil properties were significantly influenced by the age of the plantation but exhibited no discreet trend. Total biomass density and total carbon density increased with increasing plantation age while no drastic variation was found in available soil organic carbon (SOC) because of insignificant variability in litter production. Total carbon, available SOC (up to 60 cm depth) and ecosystem carbon in the three age class plantations fell in the ranges of 54.51–59.91, 48.18–55.73, and 104.81–110.77 Mg ha−1, respectively. The carbon sequestration potential of Gmelina arborea is higher compared to other reported species and highly supportive of converting unutilized agricultural landscapes to reduce the atmospheric carbon dioxide in future.