Land-use conversion affects soil organic carbon (SOC) dynamics. Therefore, an in-depth study of change in SOC, SOC pool, fractions of SOC and enzymatic activities of soil microbial biomass carbon (SMBC) and dehydrogenase (DHA) with the conversion of forest land to jhum, fallow jhum and settle cultivation use has been undertaken on the hills of Arunachal Pradesh of India. Geo-referenced soil samples from eight different locations, each from different land uses were collected at three depth. One part of the soil sample had been used for the analysis of SOC and its carbon fraction. The second portion was kept in a deep freezer for determining SMBC and DHA. The third part was used for the analysis of bulk density. The result revealed that the highest loss of SOC pool was recorded in jhum land (41.8 to 13.4%), and the labile carbon was also found to decrease in jhum land. The highest SMBC was observed on the surface soil of the natural forest; the highest DHA was found in the natural forest; and the lowest DHA was recorded in jhum land. This study found that the converting natural forest to jhum reduces SOC storage, enzymatic activities and C fractions significantly whereas fallow jhum shows sign of recovery because all of these parameters improved when compared to the jhum land-use system. This study also confirms that the fallow period helps restore the initial situation.
The eastern Himalayas, one of the important hotspots of global biodiversity, have a rich diversity of wild edible fruit trees. The fruits of these tree species have been consumed by the tribal people since time immemorial. However, there is limited information available on the biochemical and antioxidant properties of the fruits. Therefore, the present investigation was undertaken to study the physico-chemical and antioxidant properties of the nine most important wild fruit trees. Among the species, Pyrus pashia had the maximum fruit weight (37.83 g), while the highest juice (43.72%) and pulp content (84.67%) were noted in Haematocarpus validus and Myrica esculenta, respectively. Maximum total soluble solids (18.27%), total sugar (11.27%), moisture content (88.39%), ascorbic acid content (63.82 mg/100 g), total carotenoids (18.47 mg/100 g), and total monomeric anthocyanin (354.04 mg/100 g) were recorded in H. validus. Docynia indica had the highest total phenolic content (19.37 mg GAE/g), while H. validus recorded the highest total flavonoids and flavanol content. The antioxidant activities of the different fruits ranged from 0.17 to 0.67 IC50 for DPPH activity and 3.59-13.82 mg AAE/g for FRAP. These fruits had attractive pigmentation of both pulp and juice and were a good potential source for the extraction of natural edible color in the food industry. The fruits also possess high market prices; Prunus nepalensis fetched $ 34.10-$ 141.5 per tree. Therefore, these fruits are rich sources of antioxidants, pigments and have a high market value for livelihood and nutritional security.
