DOI: http://dx.doi.org/10.1016/j.ecolecon.2011.11.004

Related posts:

1. Abandoned Farmlands Are Key To Sustainable Bioenergy
2. Tropical forests were the primary sources of new agricultural land in the 1980s and 1990s

Forest ecosystems store approximately 45% of the carbon found in terrestrial ecosystems, but they are sensitive to climate-induced dieback. Forest die-off constitutes a large uncertainty in projections of climate impacts on terrestrial ecosystems, climate–ecosystem interactions, and carbon-cycle feedbacks. Current understanding of the physiological mechanisms mediating climate-induced forest mortality limits the ability to model or project these threshold events. We report here a direct and in situ study of the mechanisms underlying recent widespread and climate-induced trembling aspen (Populus tremuloides) forest mortality in western North America. We find substantial evidence of hydraulic failure of roots and branches linked to landscape patterns of canopy and root mortality in this species. On the contrary, we find no evidence that drought stress led to depletion of carbohydrate reserves. Our results illuminate proximate mechanisms underpinning recent aspen forest mortality and provide guidance for understanding and projecting forest die-offs under climate change.

doi: http://dx.doi.org/10.1073/pnas.1107891109

Related posts:

1. A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests
2. Permafrost carbon-climate feedbacks accelerate global warming

5. Under the ‘business as usual’ scenario, population models projected a 90% decline in the size of tapped and untapped populations within 50 years and a 50% decline in frankincense yield within 15 years. Model simulations for restoration scenarios revealed that populations and frankincense production could only be sustained with intensive management leading to full sapling recruitment and a 50–75% reduction in adult mortality.

DOI: http://dx.doi.org/10.1111/j.1365-2664.2011.02078.x

No related posts.

Developing countries are required to produce robust estimates of forest carbon stocks for successful implementation of climate change mitigation policies related to reducing emissions from deforestation and degradation (REDD). Here we present a “benchmark” map of biomass carbon stocks over 2.5 billion ha of forests on three continents, encompassing all tropical forests, for the early 2000s, which will be invaluable for REDD assessments at both project and national scales. We mapped the total carbon stock in live biomass (above- and belowground), using a combination of data from 4,079 in situ inventory plots and satellite light detection and ranging (Lidar) samples of forest structure to estimate carbon storage, plus optical and microwave imagery (1-km resolution) to extrapolate over the landscape. The total biomass carbon stock of forests in the study region is estimated to be 247 Gt C, with 193 Gt C stored aboveground and 54 Gt C stored belowground in roots. Forests in Latin America, sub-Saharan Africa, and Southeast Asia accounted for 49%, 25%, and 26% of the total stock, respectively. By analyzing the errors propagated through the estimation process, uncertainty at the pixel level (100 ha) ranged from ±6% to ±53%, but was constrained at the typical project (10,000 ha) and national (>1,000,000 ha) scales at ca. ±5% and ca. ±1%, respectively. The benchmark map illustrates regional patterns and provides methodologically comparable estimates of carbon stocks for 75 developing countries where previous assessments were either poor or incomplete.

doi: http://dx.doi.org/10.1073/pnas.1019576108

Related posts:

1. Monitoring and estimating tropical forest carbon stocks: making REDD a reality
2. Re-evaluation of forest biomass carbon stocks and lessons from the world’s most carbon-dense forests

Strategies for the reduction of greenhouse gas emission in agriculture have been debated for some time, especially in Brazil, where the agricultural sector is an important contributor to the national emission balance. The present study focuses on the change in greenhouse gas balance from the conversion of sugarcane areas from burned to green harvest, considering both agricultural and mobile sources. The results are presented in terms of CO2 equivalent, using the gases CO2, CH4 and N2O, and indicate that N synthetic fertilizer and burning of residues are responsible for the higher emissions observed in green and burned areas, with 1167.6 and 941.0 kg CO2equiv. ha−1 y−1, respectively. The sugarcane burning plot presented the highest emissions in our scope, with 3103.9 kg CO2equiv. ha−1 y−1. Our estimates indicate that conversion from burned to green plot could save from 310.7 (not considering soil carbon sequestration) to 1484.0 kg CO2equiv. ha−1 y−1 (considering soil carbon sequestration). The development of ethanol and sugar production in Brazil should certainly move towards the reduction of burning practice and diesel use, avoiding some tillage operations and should also adopt more efficient fertilization practices to reduce N fertilizer inputs, attaining reduction in greenhouse gas emissions from the sugarcane agricultural sector.

doi:10.1016/j.agee.2011.02.014

No related posts.

► Sewage sludge improves soil characteristics at a short term. ► The use of the sludge as fertilizer increases productivity at medium term in Quercus rubra afforested lands. ► Pasture and tree establishment in a sandy soil improves soil characteristics at medium term. ► Biodiversity, mainly of dicot species, is improved as soil cation availability is increased.

doi:10.1016/j.agee.2011.02.009

No related posts.