Impact of land use changes on soil quality and species diversity in the Vindhyan dry tropical region of India

Current practices of conducting forest management plans in the Amazon may risk the survival of timber species

Measurement of the recovery of wood stocks in logging areas in the Amazon helps to understand the efficiency of policies for the use and conservation of native forests. This work evaluated the effects of logging on the dynamics and production of commercial species in the short and medium term in a conservation unit in the state of Rondônia. Structural patterns of the species as a function of mortality and recruitment rates, patterns of average increment in diameter, and estimates of forest production in the short and medium term were analyzed. The study was carried out in an area designated as Annual Production Unit 2 of Forest Management Unit III of Jamari National Forest. In addition to legalized harvesting, there are reports of illegal logging in the area as of 2015. Inventory data from 2011, 2015, and 2018 were used, considering trees of commercial value with a diameter at breast height (DBH) greater than 10 cm. Mortality rate, recruitment, periodic annual increment, absolute tree density, basal area, and commercial volume, by species and DBH classes, as well as the similarity of the species regarding the growth pattern. The population structure of species over the years was affected by tree mortality, mainly due to damage caused by illegal logging. Mean increment values varied by species and diameter classes, and six species represented 72% of the total volume of wood stock. It is important to review the criteria for sustainable forest production in the long term. Thus, it is necessary to promote species diversity and improve public authorities' capacity to enforce and of the private sector to comply with legislation. This, in turn, will enable the development of strategies to make the consumption of legal wood more rational.

Assessment of factors that influence carbon storage: An important ecosystem service provided by mangrove forests

Mangrove ecosystem services (ES) support the global carbon (C) cycle. This study aimed to assess factors affecting the loss or gain of C stocks in mangrove forests in Thailand. Two fundamental considerations were taken into account, including ES supplied by mangroves from the perspective of C stocks, and the potential for C loss resulting from human activities conducted in mangrove forests. Three different land-use types in mangrove forests were studied: an area encroached upon by the local population (L1), a conservation area (L2), (both of which were dominated by the mangrove species Avicennia alba), and a seaside area. Based on their average height and diameter at breast height (DBH), most of the mangrove trees were determined to be young. The highest importance value index (IVI) was seen for A. alba, at 224.73 (L1) and 213.79 (L2). Above- and below-ground C levels were 189.97 t-Cha^-1, 77.11 t-Cha^-1 in L1 and 81.73 t-Cha^-1, 32.54 t-Cha^-1 in L2. Soil C stocks were 60.95 t-Cha^-1 (L1) and 43.71 t-Cha^-1 (L2). Statistical analysis indicated that nitrogen was the crucial factor influencing soil C in both L1 and L2. Overall, the total mangrove C stocks in L1 were estimated to be 328.64 t-Cha^-1, which surprisingly was higher than in L2, at 290.34 t-Cha^-1. The potential change in C stocks was then assessed. This showed that demand for mangrove resources resulted in the permanent loss of C stocks, particularly within plant communities, as the major fraction of C was from above-ground C stores. The loss of 1 ha of mangrove vegetation was estimated to result in the loss of 77.71-189.97 t-C/ha^-1 and 32.54-81.73 t-Cha^-1 in L1 and L2, respectively. Different approaches to mangrove management based on the differing supply and demand for ES are recommended.

Effects of long-term afforestation and natural grassland recovery on soil properties and quality in Loess Plateau (China)

Long-term afforestation has important implications on soil properties and quality in semi-arid areas. A large-scale afforestation project has been carried out in the Loess Plateau in the last 20 years. This work aims to study the afforestation (Robinia pseudoacacia, Caragana korshinskii and natural grassland recover 10, 20, 30, and 40 years after) impacts on soil properties and quality. The results showed that coverage and root biomass (RB) was the highest 30 years after the restoration in Robinia pseudoacacia and Caragana korshinskii treatments, while the highest 40 years post-restoration in natural grasslands. Sand content and BD showed the highest values 10 years post afforestation in all study areas. Clay, Silt, mean weight diameter (MWD), and geometric mean diameter (GMD) in Robinia pseudoacacia, Caragana korshinskii had the highest values 30 years after the afforestation, while in natural grasslands, this was observed 40 years after. In Robinia pseudoacacia, Caragana korshinskii treatments, soil moisture content (SMC) reached the highest levels 30 years post afforestation at 20-40 and 40-60 cm. Regarding natural grasslands, SMC had the highest values 40 years post-afforestation. Sand content and BD increased with soil depth, while the opposite was identified in RB, clay, silt, MWD, GMD and SMC. In Robinia pseudoacacia and Caragana korshinskii treatments, soil organic matter, total nitrogen, available nitrogen, total phosphorous, and available phosphorus had the highest levels 40 years post-restoration at 0-20 cm, while at 20-40 and 40-60 cm, the highest concentrations were identified 30 years after. In all the treatments, the soil quality index (SQI) was the highest 40 years post-restoration. The values of SQI were always higher in natural grasslands than in Robinia pseudoacacia and Caragana korshinskii treatments. Overall, natural recovery (natural grasslands) is more efficient than afforestation (Robinia pseudoacacia and Caragana korshinskii treatments) in soil quality.