Celtis australis is an important agroforestry tree in the Himalayan region providing major fodder to the livestock and many other needs for sustaining life in local rural communities. Including their fodder value and wide altitudinal distribution ranges, it is extracted by the villagers in large scale during the lean period (May to June). Thus, the aim was to understand the nutritive values of the species influenced by the altitude and harvesting season. For this investigation, leaves of C. australis were collected from four different altitudes during the months of February to December. The nutritive value of collected foliage, i.e., dry matter, ash, potassium, calcium, phosphorus, crude protein, crude fiber, starch, sugar, and phenolic were estimated by using stranded methods. The results of present study reveal that significant seasonal variations have been observed for the chemical composition of C. australis tree foliage collected from different altitudes. On an average, between seasons, crude protein ranged from 9.17 to 16.97%, phosphorus 0.08 to 0.16%, potassium 0.28 to 0.76%, crude fiber 13.94 to 19.80%, sugars 1.11 to 1.83%, and starch 4.79 to 6.53%. Altitude also significantly influenced nutritive content. Between altitudes, phosphorus ranged from 0.10 to 0.11%, potassium 0.42 to 0.50%, crude protein 12.66 to 14.02%, crude fiber 1.61 to 1.71%, sugars 1.45 to 1.66%, starch 4.71 to 6.31%, and phenolic 0.43 to 0.78%. Potassium, calcium, crude protein, and starch were significantly positively correlated with altitude of foliage collection. However, dry matter content, phosphorus, and soluble sugars, significantly correlated inversely with altitude.

Forests face a variety of threats in the modern era. Agroforestry systems, both traditional and introduced, have a tremendous capacity for providing sustainable resources and combating the impact of global climate change. Indigenous agroforestry and forest land-use systems are important reservoirs for biodiversity conservation and ecosystem services, providing a potential contribution to livelihood security for rural communities. This study aimed to assess the tree diversity and carbon stock of agroforestry and adjoining forests along altitudinal gradients, ranging between 700 and 2200 masl (i.e., lower, middle, and upper altitudes) by laying sample plots randomly of a size of 20 × 20 m². In the forest land-use system, the maximum Importance Value Index (IVI) included Dalbergia sissoo (71.10), Pyrus pashia (76.78), and Pinus roxburghii (79.69) at the upper, middle, and lower elevations, respectively, whereas, in the agroforestry land-use system, the IVI reported for Ficus semicordata was 43.05 at the upper, while for Grewia optiva it was at 53.82 at the middle and 59.33 at the lower altitudes. The below-ground biomass density (AGBD) was recorded as 1023.48 t ha⁻¹ (lower), 242.92 t ha⁻¹ (middle), and 1099.35 t ha⁻¹(upper), while in the agroforestry land-use system, the AGBD was 353.48 t ha⁻¹ (lower), 404.32 t ha⁻¹ (middle), and 373.23 t ha⁻¹ (upper). The total carbon density (TCD) values recorded were 630.57, 167.32, and 784.00 t ha⁻¹ in forest land-use systems, and 227.46, 343.23, and 252.47 in agroforestry land-use systems for lower, middle, and upper altitudes, respectively. The Margalef’s Index values for agroforestry and forests ranged from 2.39 to 2.85 and 1.12 to 1.30, respectively. Soil organic carbon (SOC) stock recorded 45.32, 58.92, and 51.13 Mg C ha⁻¹ for agroforestry and 61.73, 42.65, and 71.08 Mg C ha⁻¹ for forest in lower, middle and upper elevations, respectively. The study suggests that selecting land use patterns can be an effective management system for tree species at different elevations for carbon storage, helping to mitigate climate change and aiding in sustainable management of ecosystems in the Garhwal Himalayas.

The management of forests is essential for the conservation of biodiversity and climate change. Studies on the variation in forest tree diversity and carbon sequestration by the forests along altitudinal gradients are limited for most parts of the Garhwal Himalaya. The present study was carried out in montane forests in a part of district Tehri of the Garhwal Himalaya, India at four different sites between altitudinal ranges of 850 to 2,200 masl (i.e., 850–1,500 masl under sub-tropical region and 1,800–2,200 masl under temperate region) for vegetation, soil, and carbon stock analysis using different parameters including the existing pressure on the sites for fuel, fodder, timber, grazing, and browsing. All the standard methods were used for vegetation and soil analysis. The highest value of tree diversity (H = 0.48) and concentration of dominance (CD = 0.95) was recorded at 850–1,100 masl altitude under sub-tropical forests. The aboveground biomass density (AGBD) and belowground biomass density (BGBD) ranged from 271 to 703.20 and 83.21 to 163.92 Mg ha^–1, respectively. The pH value ranged from 5.63 to 6.86 (0–15 cm) and 6.17 to 7.21 (15–30 cm). Similarly, soil organic carbon (SOC) was reported to range from 1.86 to 2.57% and 1.78 to 2.44% at 0–15 cm and 15–30 cm depths, respectively. Available nitrogen (N) under temperate forests was reported to be significantly higher than at other altitudes. Among the studied parameters, a significant positive correlation was reported between the pH of the soil and the Shannon–Wiener and Margalef diversity indices. The study revealed that the sub-tropical region was more diversified in terms of tree species whereas soil properties were reported to be better in the temperate region. Among the species in the study region, Pinus roxburghii, Boswellia serrata, Quercus leucotrichophora, and Cedrus deodara have shown good potential for carbon storage. Thus, based on the dominant and associated species present in the area, forest management activities may be followed for the survival and regeneration of species with the potential of being the next dominant species in the future.

Bhimal (Grewia oppositifolia) is the most important agroforestry tree species used for fodder, fuel and fiber in the Himalayan region. In the present study, G. oppositifolia-based traditional agroforestry systems were selected for the estimation of carbon stock and the production potential of barnyard millet (Echinochloa frumentacea) and finger millet (Eleusine coracana), with two elevational ranges, i.e., 1000–1400 and 1400–1800 m amsl, in Garhwal Himalaya, India. The results of the investigation showed a decline in the growth and yield attributes of both the millet crops under the G. oppositifolia-based agroforestry system at both elevations as compared to their respective control sites (sole crops). Among the elevations, the total number of tillers per plant (2.70 and 2.48), the number of active tillers per plant (2.18 and 2.25), panicle length (17.63 cm and 6.95 cm), 1000-seed weight (5.49 g and 4.33 g), grain yield (10.77 q ha⁻¹ and 11.35 q ha⁻¹), straw yield (37.43 q ha⁻¹ and 30.15 q ha⁻¹), biological yield (48.21 q ha⁻¹ and 41.51 q ha⁻¹) and the harvest index (22.53% and 27.78%) were recorded as higher in the lower elevation in both E. frumentacea and E. coracana, respectively, while plant population per m² (18.64 and 25.26, respectively) was recorded as higher in the upper elevation. Plant height for E. frumentacea (180.40 cm) was also observed to be higher in the upper elevation, while for E. coracana (98.04 cm), it was recorded as higher in the lower elevation. Tree carbon stock was reported negatively with an increase in altitude. The maximum amount of sequestered carbon in the tree biomass for G. oppositifolia was 23.29 Mg ha⁻¹ at the lower elevation and 18.09 Mg ha⁻¹ at the upper elevation. Total carbon stock in the tree biomass was reported to be the highest (15.15 Mg ha⁻¹) in the 10–20 cm diameter class, followed by 20–30 cm (6.99 Mg ha⁻¹), >30 cm (2.75 Mg ha⁻¹) and the lowest (2.32 Mg ha⁻¹) in the <10 cm diameter class. The results show that the yield of E. frumentacea and E. coracana was not reduced so severely under the G. oppositifolia system; however, keeping in mind the other benefits of this multipurpose tree, i.e., carbon sequestration and socioecological relevance, farmers can get benefit from adopting these crops under G. oppositifolia-based agroforestry systems.