Altitudinal and aspect-driven variations in soil carbon storage potential in sub-tropical Himalayan forest ecosystem: assisting nature to combat climate change.

Forest soils serve as the greatest sink of terrestrial carbon (C) and have a significant impact on worldwide or regional C cycling. By reducing emissions and enhancing the C storage in forests, the environmental monitoring function of a forest ecosystem may be ensured. The study focused on measuring the densities of major nutrients in soil to gain insight into the C and nitrogen dynamics of the Himalayan sub-tropical forest ecosystem of India besides supplementing the information about the C storage potential of these forest soils. The study examined the physico-chemical properties and nutrient densities across three altitudinal ranges viz., 600-800 m (A1), 800-1000 m (A2) and 1000-1200 m (A3) and two aspects, i.e. Northern (N) and Southern (S) in a randomized complete block design and data collection was done from 24 main sample plots (3 altitudinal ranges × 2 aspects × 4 replications). The soil pH, electrical conductivity, and bulk density observed a decreasing pattern with an increase in altitude, whereas a reverse trend was observed in soil organic C (SOC), total nitrogen and available phosphorus. The SOC and total nitrogen densities ranged from 20.08 to 48.35 Mg ha-1 and 2.56 to 4.01 Mg ha-1, respectively in an increasing trend from A1 to A3. The northern aspect exhibited significantly higher SOC and nitrogen densities than the southern aspects. The C storage potential of forest soils followed the order A1 < A2 < A3 with significantly higher potential (nearly 1.5 times) compared to those on the southern aspect. There was a consistently significant increase in the C:N ratio (CNR) with a maximum value (10.51) at A3 and minimum value (8.37) at A1, however the effect of aspect remained insignificant. This research underscores the importance of considering altitude and aspect when planning forest restoration efforts, as these factors have a substantial influence on soil properties, C storage potential and CNR. Understanding the significance of CNR is critical, as it serves as a key indicator of greenhouse gas (GHG) emissions from forest soils. Ultimately, these findings empower policymakers and conservationists to make informed decisions that can contribute to the sustainable management of Himalayan forests and the global fight against climate change.

Agroforestry systems in the mid-hills of the north-western Himalaya: A sustainable pathway to improved soil health and climate resilience.

Identifying the new tree crop combinations plays an important function in transforming the low input agriculture into land units with high economic returns, increasing carbon (C) sink and nutrients storage capacity, and acting as a panacea to achieve Sustainability Development Goals (SDGs). The present study aims to evaluate various tree-crop combinations for (i) biomass production, (ii) carbon accumulation, and (iii) soil nutrient enrichment of traditional and commercially evolved eight agroforestry systems (AFSs), including agri-silvi-horticulture system, agri-silviculture system, silvi-pasture, fruit tree, fodder tree, bamboo, melia and poplar based AFSs with sole cropping system in the mid-hill zone of the north-western Himalaya. The results demonstrated that poplar based AFS accumulated a higher amount of biomass (130.87 Mg ha-1) and carbon (65.44 Mg ha-1) closely followed by melia-based AFS. The C stored in leaf litter was higher (0.66 Mg ha-1) in poplar-based AFS, however, soil C stock was maximum (114.69 Mg ha-1) under bamboo-based AFS. Overall, the Melia based AFS exhibited a higher rate of carbon dioxide mitigation (19.30 Mg ha-1 yr-1) and C-sequestration (5.26 Mg ha-1 yr-1) than other studied AFSs. Moreover, soil macro-nutrients (available N, P, K, S and Ca) were maximum under bamboo-based AFS, on the other hand, the fruit-based AFS had the higher concentrations of micro-nutrients i.e., Cu (3.05), Fe (31.10 mg g-1) and Mn (17.31 mg g-1). The soil microbial counts were higher in poplar-based AFS, whereas, the soil quality index improved significantly under bamboo based and fruit tree based AFSs. Hence, it can be concluded that the experimentally evolved AFSs represent an effective approach for boosting C-sequestration, soil fertility, regenerating the soil and sustainability of hill agriculture in the north-western Himalayas over traditional AFSs and sole cropping.

Seasonal variations in the nutritive value of fifteen multipurpose fodder tree species: A case study of north-western Himalayan mid-hills.

Multipurpose tree species are recognized as an important fodder source for livestock, but their potential remains untapped due to dearth of knowledge about their nutritive value. Therefore, 15 MPTs, i.e., Acacia catechu, Albizia chinensis, Bauhinia variegata, Celtis australis, Ficus roxburghii, Grewia optiva, Leucaena leucocephala, Melia composita, Morus serrata, Olea glandulifera, Ougienia oojeinensis, Pittosporum floribundum, Quercus glauca, Q. leucotrichophora and Salix tetrasperma were evaluated for nutritional characteristics, relative nutritive value index (RNVI), palatability index and farmers' preference on a seasonal basis in north-western Himalayas mid-hills. Most of the nutritive and mineral content decreased as leaves matured with the exception of ether extract, calcium, copper, organic matter and carbohydrate content, while cell-wall constituents and anti-nutritional contents increased. Overall, M. serrata had the highest RNVI in spring and summer, while G. optiva during autumn and winter. Similarly, L. leucocephala had the highest palatability (97.86%), while M. composita (38.47%) had the lowest one. Additionally, G. optiva was the most favored MPT for livestock among farmers, while M. composita was the least ones. The outcome of the study will help policy makers, planners and farm managers in establishing large scale plantations of highly nutritious and palatable species, like G. optiva, L. leucocephala, B. variegata, and M. serrata for year-round supply of green leaves and as a supplement to low-quality feed.

Variation of biomass and carbon pool with NDVI and altitude in sub-tropical forests of northwestern Himalaya.

In the present study, forests at three altitudes, viz., A1 (600-900 m), A2 (900-1200 m) and A3 (1200-1500 m) above mean sea level having normalised differential vegetation index (NDVI) values of N1 (0.0-0.1), N2 (0.1-0.2), N3 (0.2-0.3), N4 (0.3-0.4) and N5 (0.4-0.5) were selected for studying their relationship with the biomass and carbon pool in the state of Himachal Pradesh, India. The study reported maximum stem density of (928 trees ha-1) at the A2 altitude and minimum in the A3 and A1 with 600 trees ha-1 each. The stem densities in relation to NDVIs were observed in the order N5 > N3 > N4 > N1 > N2 and did not show any definite trend with increasing altitude. Highest stem volume (295.7 m3 ha-1) was observed in N1 NDVI and minimum (194.1 m3 ha-1) in N3 index. The trend observed for stem biomass at different altitudes was A3 > A1 > A2 and for NDVIs, it was N5 > N1 > N4 > N2 > N3. Maximum aboveground biomass (265.83 t ha-1) was recorded in the 0.0-0.1 NDVI and minimum (169.05 t ha-1) in 0.2-0.3 NDVI index. Significantly, maximum total soil carbon density (90.82 t C ha-1) was observed in 0.4-0.5 NDVI followed by 0.3-0.4 NDVI (77.12 t C ha-1). The relationship between soil carbon and other studied parameters was derived through different functions simultaneously. Cubic function showed highest r 2 in most cases, followed by power, inverse and exponential function. The relationship with NDVI showed highest r 2 (0.62) through cubic functions. In relationship between ecosystem carbon with other parameters of different altitudinal gradient and NDVI, only one positively significant relation was formed with total density (0.579) through cubic function. The present study thus reveals that soil carbon density was directly related to altitude and NDVIs, but the vegetation carbon density did not bear any significant relation with altitude and NDVI.

In vitro propagation of spine gourd (Momordica dioica Roxb.) and assessment of genetic fidelity of micropropagated plants using RAPD analysis.

An efficient protocol for rapid in vitro clonal propagation of spine gourd (Momordica dioica Roxb.) genotype RSR/DR15 (female) and DR/NKB-28 (male) was developed through enhanced axillary shoot proliferation from nodal segments. Maximum shoot proliferation of 6.2 shoots per explant with 100 % shoot regeneration frequency was obtained from the female genotype on Murashige and Skoog's (1962) medium supplemented with 0.9 µM N6-benzyladenine (BA) and 200 mg l(-1) casein hydrolysate (CH). While from the male genotype the optimum shoot regeneration frequency (86.6 %) and 6.4 shoots per explant was obtained on MS medium supplemented with 2.2 µM BA. CH induced vigorous shoots, promoted callus formation, and proved inhibitory for shoot differentiation and shoot length, especially in explants from male genotype. Rooting was optimum on half-strength MS medium (male 92.8 %, female 74.6 %) containing 4.9 µM indole-3-butyric acid (IBA). Plantlets were transferred to plastic cups containing a mixture of cocopit and perlite (1:1 ratio) and then to soil after 2-3 weeks. 84 % female and 81 % male regenerated plantlets survived and grew vigorously in the field. Genetic stability of the regenerated plants was assessed using random amplified polymorphic DNA (RAPD). The amplification products were monomorphic in the in vitro propagated plants and similar to those of mother plant. No polymorphism was detected revealing the genetic integrity of in vitro propagated plants. This micropropagation procedure could be useful for raising genetically uniform planting material of known sex for commercial cultivation or build-up of plant material of a specific sex-type.