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This study was conducted in a temperate mixed oak–pine forest of Central Himalaya, India to (i) evaluate altitudinal and seasonal variations in the microbial biomass carbon (C), nitrogen (N) and phosphorus (P) and (ii) analyse the relationships between soil microbial biomass C, N and P and physico-chemical properties of soil. Three permanent plots were established in natural forest stands along an altitudinal gradient, three replicates were collected seasonally from each site, and microbial biomass (C, N and P) were determined by a fumigation extraction method. Microbial biomass C, N and P decreased significantly (p < 0.01, correlation coefficient 0.985, 0.963, 0.948, respectively) with increasing altitude having maximum values during rainy season and minimum values during winter season. Microbial biomass C, N and P showed positive correlations with silt particles, water holding capacity, bulk density, soil moisture, organic C, total N and P and negative correlations with sand particles, porosity and soil pH. Microbial biomass C was strongly associated with soil microbial N (r = 0.80, p < 0.01) and P (r = 0.89, p < 0.01) content and soil microbial biomass N and P also showed a strong linear relationship (r = 0.92, p < 0.01). Soil microbial biomass exhibited weak seasonality and was highly influenced by altitude and abiotic variables. The significantly high microbial C, N and P during the rainy season (p < 0.01) and low microbial biomass during the winter season may be due to higher immobilization of nutrients from decomposing litter by microbes as the decomposition rate of litter and microbial activity are at their peak during the rainy period. The microbial C:N ratio indicated that soil fertility is influenced by species composition. Our findings suggested that high microbial biomass and low C:N ratios during the rainy season could be considered a nutrient conservation strategy of temperate mixed oak–pine forest ecosystems.

Invasive plant species pose a serious threat to agricultural yield, although how the threat varies with the distance of crops from invasive plants remains unclear. Therefore, utilizing this viewpoint, objectives were formulated to quantify differences in the native vegetation and performance of crops growing near A. adenophora–invaded (treatment plots) and uninvaded ridges (control plots) in the terraced agricultural fields of Kumaun Central Himalaya. Morphological and yield parameters of two crops, viz. rice (Oryza sativa L.) and soybean (Glycine max L.), were assessed systematically by laying parallel transects from the ridge of the field up to 5 m towards the centre of the field in three equal distance intervals of 1 m in the order: 0–1 m, 2–3 m, and 4–5 m. Crofton weed showed 95–100% crown cover throughout invaded ridges/risers of terraced fields, with stem densities of 134–208 ind. m−2 and an average basal area of 0.15 cm2. The total mean density of herbs (other than A. adenophora) in invaded ridges/risers decreased by 38–85% compared to uninvaded ridges, but species richness increased by 31–37%. Soil nutrient availability was high across invaded ridges/risers as well as crop fields. The average irradiance level near uninvaded ridges was 19.6 ± 1.80%, and near invaded ridges, it was 1.8 ± 0.31%. Compared to straw, root, and grain yields obtained at the farthest distance, the yield of rice near uninvaded ridges was reduced by 27%, 19%, and 33%, while near invaded ridges, it was reduced by 37%, 39%, and 43%, respectively; the yield of soybean near uninvaded ridges declined by 62%, 66%, and 42%, while near invaded ridges, it decreased by 59%, 69%, and 47%, respectively. Compared to the values obtained at the farthest distance, the harvest index (HI) of rice near ridges was reduced by 7% and 13%, while the HI of soybean increased by 15 and 10% across uninvaded and invaded field ridges, respectively. The findings indicated that the Crofton weed could suppress field crops and could form a single dominant population in the invaded area, causing a serious threat to the plant community, its diversity, and the yield of the native agroecosystem in the foreseeable future if timely management actions would not be taken.

Carbon stock assessment in various ecosystems is vital for monitoring the health of these ecosystems and national accounting for the United Nations convention on climate change. The influence of various anthropogenic drivers on carbon stock in different ecosystems has not been examined comprehensively. This study aims to determine the impact of anthropogenic pressures (lopping, cutting, grazing) on soil physico-chemical properties and carbon stock in four temperate broadleaf forests dominated by different species of oak, viz., Banj oak (Quercus leucotrichophora), Rianj oak (Quercus lanuginosa), Moru oak (Quercus floribunda) and Kharsu oak (Quercus semecarpifolia) along an elevation gradient from 1700–3000 m asl in Gori valley, western Himalaya. Biomass data were collected from 120 quadrats of 10 × 10 m size at three distinct altitudes (4 forest sites × 3 altitudes × 10 quadrats) and analysed for carbon stock, whereas soil samples were randomly collected in triplicate from three depths of each altitude of the forest site and further analysed for their physico-chemical properties. A total of 767 individual trees with a diameter of ≥31 cm were measured at twelve sites and standing biomass was estimated following the growing stock volume equations. Mean carbon stock was highest in Moru oak (396.6 ± 29.5 Mg C ha−1) and lowest in Banj oak forest (189.3 ± 48.6 Mg C ha−1). We also found soil to be the largest pool of forest carbon (43.0–59.7%) followed by aboveground biomass (31.5–45.0%), belowground biomass (8.4–11.7%) and litter (0.4–0.5%). The basal area showed significant effect on altitude and carbon stock, whereas disturbance showed significant (p < 0.05) negative correlation with the total carbon stock. Soil nitrogen exhibited a significant positive correlation (R2 = 0.60) with the basal area, indicating that nitrogen enhances tree growth and forest carbon stock. However, anthropogenic disturbance showed a significant negative impact on the basal area, soil nutrients and carbon stock of oak forests. This concludes that forest structure, anthropogenic pressure and soil parameters contribute to the carbon stock of the area. Considering the significance of these overexploited oak forests, it is recommended to conserve the old-growth forest species in the study area, since they have the highest carbon accumulation potential.

ABSTRACT Grasslands in the Kumaun Himalayan region, formed largely due to degradation of forests by natural and anthropogenic disturbances, are ecologically significant but poorly studied in terms of dry matter dynamics and net primary productivity. This study compared seasonal biomass and productivity variations in grasslands under two contrasting forest zones (Banj oak and Chir pine). Three permanent plots were established in each zone and within each of these plots 10 quadrats of 1m × 1m were placed randomly on monthly basis. Maximum density, total basal area, diversity and live aboveground biomass were observed during the rainy season, while dead shoot biomass peaked in winter. Aboveground net productivity ranged from 280.96 g m-2 to 394.83 g m-2 for oak and pine zone grassland, respectively. All biomass compartments varied significantly with season, site, and their interaction (p<0.05). High aboveground biomass and productivity during rainy season indicates that precipitation promotes aboveground biomass in grasslands. Oak zone grassland showed lower productivity and nutrient content as compared to pine zone due to greater grazing and human pressure. This study concludes that grassland productivity was directed aboveground during the monsoon season and belowground during post-monsoon season, with environmental and anthropogenic factors driving these patterns. Understanding these dynamics is crucial for managing and conserving Himalayan grassland ecosystems.

Coriaria nepalensis , a nitrogen-fixing actinorhizal shrub, is a prominent and successful colonizer of bare rocks and landslide affected degraded lands. Field experiments were conducted to determine the differences in biomass decomposition and nutrient release pattern of different plant parts of C. nepalensis using litter bag technique. Results showed that the leaves decomposed completely within 6 months while only 46.55% of the lateral roots were decomposed with slowest decomposition rate of 0.14% day –1 . The decomposition rate was in the order: Leaves > Reproductive parts > Twigs (< 5 mm) > Twigs (> 5 mm) > Bark > Fine roots > Lateral roots. The decay rate coefficient was highest (0.003–0.014) for leaves and lowest (0.001–0.002) for lateral roots. During the decomposition cycle (364 days), overall increase was reported in nitrogen and phosphorus concentration, while potassium concentration decreased continuously in residual litters. The nutrient mobility was in the order: K > P > N. Climatic factors like temperature, relative humidity and rainfall significantly affected the decomposition process and among these factors, rainfall pattern emerged as a most effective environmental driver. Thus, taking into account initial nutrient content, nutrient release and decay rates, the leaves and reproductive parts of C. nepalensis proved to be more important as nutrient source than other components.

This study examined forest structure, composition, and regeneration patterns of two sites, Tolma-Lata-Raini (TLR) and Bhyundar-Ghangaria (BG). Both sites are located within the temperate zone along the altitudinal gradient between 2,800 to 3,400 m asl of Nanda Devi Biosphere Reserve (NDBR) in the Western Himalayan Region of India. We recorded a total of 223 species of vascular plants (Angiosperm, Gymnosperm, and Pteridophytes) within the study area. Of the recorded species, plants within the family Rosaceae were dominant (17.69%), followed by Asteraceae (14.97%) and Ranunculaceae (12.93%). Betula utilis had the highest tree density (724 and 324 individuals ha -1 ) and species cover (44% and 36%) at both TLR and BG sites, followed by Pinus wallichiana (24%) and Cedrus deodara (15%), respectively. In BG site, 56% of tree species showed fair regeneration (i.e., seedling density > sapling density ≤ adult density), 22% good (i.e., seedling density > sapling density > adult tree density), 11% exhibited poor (i.e., species survived only in the sapling stage but not in the seedling stage), and the remaining (11%) indicated no regeneration. Comparatively, at TLR site, 40% of the tree species showed fair regeneration, 40% good, and the remaining 20% showed no regeneration. Across the two sites, species richness and diversity significantly decreased as the altitudinal gradient increased. Vegetation structure and soil properties also revealed differences between the southern and northern aspects. The baseline information generated in this study is helpful in designing effective conservation and management measures for these ecologically sensitive and important ecosystems. To effectively monitor changes in vegetation structure, species composition, and regeneration, we suggest that permanent vegetation plots with meteorological stations be established across the region for long-term monitoring of forest dynamics in response to the changing climate and anthropogenic pressures.

The seasonal phenological segregation observed among various species within a plant community can be interpreted as a form of niche differentiation that facilitates the coexistence of these species. In the present study, life forms and phenological attributes of dominant plant species in temperate semi-natural grasslands of Central Himalaya, India, were assessed between January 2022 and December 2022. This study was carried out in three sites in different forest zones, viz. oak, cypress and pine. In each site, plots measuring 0.5 hectares were established and phenological assessments were conducted within each of these plots. A total of 50, 36, and 49 herbaceous species were identified in the grasslands of oak, cypress and pine zones, respectively, with these species categorized into five distinct life form classes. In the grasslands of both oak and pine zones, hemicryptophytes emerged as the predominant life form, whereas in the cypress zone grasslands, it was found that chamaephytes take precedence. The differences observed in the classifications of life forms can be ascribed to the geographical distribution and the biotic interactions present in these sites. The three grasslands exhibit comparable climatic conditions and day lengths, resulting in no significant variations in soil temperature, light intensity or overall climatic factors. The majority of species commenced their flowering phase during the monsoon season, attributed to the favorable conditions characterized by warm, humid weather and adequate soil moisture. Various phenological events, including germination, growth, and senescence, are significantly affected by weather and climate, and their timing subsequently influences ecosystem processes in a reciprocal manner. This study provides valuable foundational data for ecological and environmental research, aiding in the comparison and distinction of plant compositions across the Himalayas and its ecosystems.

Introduction: Riverine forests in the Himalaya represent a biodiverse, dynamic, and complex ecosystem that offers numerous ecosystem services to local and downstream communities and also contributes to the regional carbon cycle. However, these forests have not been assessed for their contribution to dry matter dynamics and carbon flux. We studied these parameters along three classes of riverine forests in eastern Uttarakhand, dominated by Macaranga, Alnus, and Quercus-Machilus forest.Methods: Using volume equations, we assessed tree biomass, carbon storage, and sequestration in the study area.Results: The total standing tree biomass in Macaranga, Alnus, and Quercus-Machilus forest ranged from 256.6 to 558.1  Mg  ha−1, 460.7 to 485.8 Mg ha−1, and 508.6 to 692.1 Mg ha−1, respectively. A total of 77.6–79.6% of vegetation biomass was stored in the aboveground biomass and 20.4–22.4% in belowground plant parts across the riverine forests. The carbon stock in Macaranga forest ranged from 115.5 to 251.1 Mg ha−1, in Alnus forest from 207.3 to 218.6 Mg ha−1, and in Quercus-Machilus forest from 228.9 to 311.4 Mg ha−1. The mean annual litterfall was accounted maximum for Quercus-Machilus forest (5.94  ±  0.54 Mg ha−1 yr.−1), followed by Alnus (5.57  ±  0.31 Mg ha−1 yr.−1) and Macaranga forest (4.67  ±  0.39 Mg ha−1 yr.−1). The highest value of litterfall was recorded during summer (3.40  ±  0.01 Mg ha−1 yr.−1) and the lowest in winter (0.74  ±  0.01 Mg ha−1 yr.−1). The mean value of net primary productivity and carbon sequestration was estimated to be highest in Quercus-Machilus forest (15.8  ±  0.9 Mg ha−1 yr.−1 and 7.1  ±  0.9 Mg C ha−1 yr.−1, respectively) and lowest in Alnus forest (13.9  ±  0.3 Mg ha−1 yr.−1 and 6.1  ±  0.3 Mg C ha−1 yr.−1, respectively).Discussion: The results highlight that riverine forests play a critical role in providing a large sink for atmospheric CO2. To improve sustainable ecosystem services and climate change mitigation, riverine forests must be effectively managed and conserved in the region.

Coriaria nepalensis is one of the shrubs which have the ability to mitigate the frequency of perilous natural events or natural calamities. This paper elucidates the nutrient dynamics of C. nepalensis shrublands in degraded hills of Kumaun Himalaya. The average nutrient concentration (N, P, and K) in aboveground components of C. nepalensis was in the following order: Foliage > Twigs > Branches > Bole wood, whereas in belowground components the order was: Fine roots > Lateral roots > Stump root. The order of contribution to total nutrient storage in vegetation was: Tree > Herbs > Shrubs. The proportion of nutrients stored in the shrub layer was in the order: N > K > P. The soil stored a maximum proportion of nutrients at each site (79.48–87.54% N, 70.47–87.88% P, 74.33–88.27% K). Maximum nutrient storage in soil and vegetation was recorded for site 3 (Barapatthar) and minimum for site 1 (Pines). The uptake of N, P, and K by vegetation ranged from 428 to 1,353 kg ha –1 yr –1 , 32–102 kg ha –1 yr –1 , and 109–479 kg ha –1 yr –1 , respectively. In the present study, the turnover time was 1.06–1.33 years for N, 1.03–1.15 years for P, and 1.02–1.13 years for K. Compartment models reflect the distribution of nutrients and net annual flux that will help to develop the management plan to maintain the fertility and productiveness of the degraded sites.