Soil carbon stock in different land-use systems in the hilly terrain of Mizoram, Northeast India

Soil carbon is one of the most affected variables to land-use change in tropics. The soil carbon flux plays a major role in regulating microbial activities and nutrient distribution in soil. This study aimed to evaluate the soil carbon stock in various land uses at different depths in the hilly terrain of Mizoram, Northeast India. Soil samples at 0-10 cm, 10-20 cm and 20-30 cm soil depths were collected from Rubber plantation (RP), Oil palm plantation (OPP), Teak plantation (TP), Bamboo Forest (BF), 5 years fallow (5YF), 10 years fallow (10YF), Tephrosia candida plantation (TCP), Horticulture garden (HORT), Homegarden (HG) and Natural forest (NF). Soil carbon stock varied significantly (p <0.05) across the land uses and depths. The soil under Tephrosia candida stand had significantly (p <0.05) higher values of C stock (73.66 Mg ha-1) which may be due to high biomass, dense vegetative cover and high C in root exudates. The minimum C stock estimated in Horticulture garden (43.28 Mg ha-1) is probably due to reduced soil organic matter. Soil carbon stock in Homegarden, Teak plantation, Bamboo forest and Rubber plantation ranged from 46.82 Mg ha-1 to 59.34 Mg ha-1 whereas 5 years and 10 years fallow land, Natural forest and Oil palm plantation ranged from 61.35 Mg ha-1 to 73.35 Mg ha-1. The study indicated that the land use change in the mountainous region significantly affected the carbon stock in the soil. A proper land use management strategies to increase the soil organic matter is recommended to enhance the carbon stock in this region

Assessment of tree diversity in tropical moist deciduous forest of Mizoram University, Northeast India

Forests are the main repository of biodiversity and play an important role in maintaining the ecological balance of nature. The status of species diversity reflects the health of the ecosystem. Therefore, the information on variation in the flora, for example,  species composition, diversity and the basal area within any ecosystem like the forest of Mizoram University campus, Tanhril village, Aizawl would be important in understanding the forest wealth of the campus. Keeping in view, the study was analyzed the composition and diversity of  Mizoram University campus by laying 16 (10 m ×10 m) quadrats at random locations during 2015-2016. A total of 35 tree species belonging to 30 genera and 22 families were recorded in the forest communities of University Campus. Aporusa octandra was the most dominant tree species with maximum 31.50 importance value index (IVI), 3.29 Shannon diversity index (H0) and 6972 Simpson’s index (D) followed by Castanopsis tribuloides (28 IVI, 0.22 H0 and 5256 D) and least dominant species recorded were: Albizia odoratissima, Anogeissus acuminate, Lithocarpus elegans, Oroxylum indicum. This study suggests that the forest patches are recovering after the establishment of the University because of adequate protection which was degraded in the past by the villager for collecting the trees for firewood, edible wild food and selecting the mature trees for felling. Therefore, further studies on regeneration potential of tree species would be crucial for the conservation of ecologically important species and to assess rates of their recovery following the disturbance

Changes in Soil Fertility and Rice Productivity in Three Consecutive Years Cropping under Different Fallow Phases Following Shifting Cultivation

Shifting cultivation commonly known as Jhum is a primitive and traditional practice carried out by Jhumiasfor centuries. Soil microbes play a vital role in regulating soil fertility and nutrient cycling in different terrestrial ecosystems. The main objective of the present study is to examine changes in soil properties (soil organic carbon, SOC; total nitrogen, TN; available phosphorus, Pavail; ammonium nitrogen, NH4-N; nitrate nitrogen, NO3-N; nitrogen mineralization, Nmin) and rice productivity for three years cropping phase in shifting cultivation stand with different fallow phases (3 years old, FL-3; 5 years old, FL-5; and 10 years old fallow, FL-10) in Mizoram. The results indicated that soil physico-chemical properties were significantly higher (p<0.05) in longer fallow (FL-10) compared to shorter fallow (FL-3). The rate of Nmin showed significant differences among seasons and showed significant increase in longer fallow (FL-10) compared to shorter fallows (FL-3 and FL-5). Rice yield and productivity showed significant increase from 3 years to 10 years. Further, soil properties and rice productivity showed significant decline from first year to third year cropping. It appears that the longer fallow have conserved better soil nutrients compared to shorter fallow. Additionally, the addition of leaf litter and fine roots had strong effect on increasing fertility and organic carbon (SOC) pool in soil that helps to enhance plant productivity in different fallow lands in hilly region of Mizoram