• Energy Research

AbstractForests are a substantial terrestrial carbon sink, but anthropogenic changes in land use and climate have considerably reduced the scale of this system1. Remote-sensing estimates to quantify carbon losses from global forests2–5 are characterized by considerable uncertainty and we lack a comprehensive ground-sourced evaluation to benchmark these estimates. Here we combine several ground-sourced6 and satellite-derived approaches2,7,8 to evaluate the scale of the global forest carbon potential outside agricultural and urban lands. Despite regional variation, the predictions demonstrated remarkable consistency at a global scale, with only a 12% difference between the ground-sourced and satellite-derived estimates. At present, global forest carbon storage is markedly under the natural potential, with a total deficit of 226 Gt (model range = 151–363 Gt) in areas with low human footprint. Most (61%, 139 Gt C) of this potential is in areas with existing forests, in which ecosystem protection can allow forests to recover to maturity. The remaining 39% (87 Gt C) of potential lies in regions in which forests have been removed or fragmented. Although forests cannot be a substitute for emissions reductions, our results support the idea2,3,9 that the conservation, restoration and sustainable management of diverse forests offer valuable contributions to meeting global climate and biodiversity targets.

Cropland residue burning is one of the major causes of the emission of greenhouse gases and pollutants into the atmosphere, and is a major global environmental problem. This study analyzes the spatiotemporal changes in greenhouse gas emissions from cropland residue burning in Chhattisgarh, India. The Moderate Resolution Imaging Spectroradiometer (MODIS) active fire data was analyzed over a 21-year (2001–2021) period, and associated greenhouse gas emissions were estimated. A total of 64,370 fire points were recorded for all land cover types. The number of cropland fires increased from 49 to 1368 between 2001 and 2021, with a burning peak observed between December and March. Fires in cropland areas contributed to 32.4% (19,878) of the total fire counts in the last 21 years. The total estimated emissions of greenhouse gases between 2001 and 2021 ranged from 421.5 to 37,233 Gg, with an annual rate of emission of 8972 Gg from wheat residue burning, and from 435.45 to 64,108.1 Gg, with an annual emission of 15,448.16 Gg from rice residue burning. The Chhattisgarh plain region was the cropland fire hotspot of the state. The present study indicates increased cropland residue-burning activity in Chhattisgarh. Therefore, there is an immediate need to develop sustainable alternative methods for agricultural residue management and eco-friendly methods for the disposal of crop residues.

Abstract Species’ traits and environmental conditions determine the abundance of tree species across the globe. The extent to which traits of dominant and rare tree species differ remains untested across a broad environmental range, limiting our understanding of how species traits and the environment shape forest functional composition. We use a global dataset of tree composition of >22,000 forest plots and 11 traits of 1663 tree species to ask how locally dominant and rare species differ in their trait values, and how these differences are driven by climatic gradients in temperature and water availability in forest biomes across the globe. We find three consistent trait differences between locally dominant and rare species across all biomes; dominant species are taller, have softer wood and higher loading on the multivariate stem strategy axis (related to narrow tracheids and thick bark). The difference between traits of dominant and rare species is more strongly driven by temperature compared to water availability, as temperature might affect a larger number of traits. Therefore, climate change driven global temperature rise may have a strong effect on trait differences between dominant and rare tree species and may lead to changes in species abundances and therefore strong community reassembly.

Wood specific gravity (WSG) is one of the most important functional traits of plants that helps in minimizing the variability of biomass estimates generated due to the inter-specific and intra-specific variations. Assemblage of an integrated inventory of WSG for various species from different forest groups, vegetation types is expected to provide crucial insights in the problems related to biomass estimation and serve as a standard reference for ecological research particularly on carbon dynamics and functional diversity studies by providing vegetational specific WSG values for a number of species at one place. Survey of literature for WSG in Indian forest communities showed that WSG values of 879 individuals belonging to 351 species, 221 genus and 77 families are available for eleven forest groups of India. Result showed that species present in a particular forest group and climatic condition showed a different value for WSG than the similar species present in other forest types and climatic conditions. It also showed that Eugenia utilis has the highest WSG (0.98) for Indian forests and it was lowest for Dalbergia sissoo (0.05). Further, we observed that in case of mature individuals, WSG value of maximum number of species was found between 0.61 to 0.80 whereas, for juvenile individuals, it was maximum between 0.41 to 0.60 indicating the role of tree diameter in WSG. In addition, we observed that tropical dry deciduous forest had the widest range of distribution for WSG. Moreover, the WSG value of species in hilly terrains showed variation with similar species present in tropical and subtropical areas. The present dataset also showed that highest WSG value was found for species present in tropical wet evergreen forest while lowest was found for tropical dry deciduous forest indicating the effect of precipitation in increasing WSG. The present dataset would of great importance for future studies particularly focusing on biomass estimation and functional trait by providing WSG values for a large number of species.