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The ongoing introduction of the exotic Grevillea robusta tree species into agroforestry systems (AFS) of the Indian Western Ghats could become a threat to both climate change mitigation and tree diversity conservation. Here, we quantified carbon (C) storage and shade tree diversity in native forests and coffee AFS under contrasted management (native versus exotic shade trees, Robusta versus Arabica systems) at 67 plots along a 3500 mm precipitation gradient in the Cauvery watershed, India. Despite a substantial reduction of shade tree cover in native AFS compared to forest (from 90% to 32% in the high precipitation area), native AFS and forests displayed high and comparable C stocks (max. 228 MgC ha −1 and 234 MgC ha -1, respectively) and tree diversity (max. 44 and 45 species, respectively). Both variables were negatively impacted by the introduction of G. robusta , especially in Robusta coffee systems (max. 158 MgC ha −1 , 12 species). The current trend toward the introduction of G. robusta in coffee AFS of the study area (exotic agroforestry) negatively affects C storage and tree diversity, especially in Robusta coffee systems. Policy makers should take advantage of the carbon-tree diversity positive correlation found in the agroforestry landscape of the Western Ghats of India to promote conservation and climate change mitigation. [ABSTRACT FROM AUTHOR]

Agroforestry has been proposed as a way to reconcile biodiversity conservation, food production and the delivery of other ecosystem services in tropical landscapes. One such a key ecosystem service, especially in the light of climate change mitigation, is carbon storage. Increasing human disturbance and management intensification, however, are known to affect the carbon storage potential of forests. Here we assessed how the above- and belowground carbon stocks in Ethiopian moist evergreen Afromontane forest co-varied with their biodiversity, and with increasing agroforestry management intensity for the production of Arabica coffee ( Coffea arabica L.). We assessed above- and belowground carbon storage in 60 plots across a gradient of agricultural intensification ranging from natural forest, over two different coffee agroforestry systems, to intensified shade plantations. We quantified the diversity of ground beetles and woody plants in the same plots. Carbon stocks in natural forests (413 ± 55.6 S.E. Mg ha −1 ) and in the most extensively managed agroforestry systems (387 ± 50.0 Mg ha −1 ) were significantly higher than those in the more intensified agroforest system (258 ± 39.4 Mg ha −1 ) and in shade plantations (219 ± 22.8 Mg ha −1 ). Diversity of woody plants, but not of ground beetles, declined with increasing management intensity and decreasing carbon stocks. Overall, this study demonstrates that extensive coffee farming in Ethiopian moist Afromontane forests is able to deliver important co-benefits in terms of woody plant species conservation and carbon storage. Given the associated coffee yield cost, it is most likely, however, that supporting payments from certification or policy mechanisms such as REDD+ are required to keep these extensive coffee agroforestry systems economically viable, which is required to avoid management intensification and associated carbon and biodiversity losses. [ABSTRACT FROM AUTHOR]

We use a dynamic global forest model to examine how U.S. tax reform could influence forest stocks and carbon sequestration. Scenario analysis estimates several impacts from adjusting current policies that affect timberland investment, area, harvests, and carbon. First, increases in tax rates faced by timberland owners cause timber assets to be revalued downward even though the physical forest is initially unchanged, resulting in substantial declines in both regeneration and management. Second, timber stocks fall over time, reflecting a decrease in investment. Third, tax revenues could increase by nearly $3.4 billion/yr compared to baseline, but at the expense of increasing trade deficits by up to $3.3 billion/yr. Fourth, timberland area could decrease by 12 million hectares. Last, cumulative carbon sequestration over the next 50 years could be reduced by more than 3 billion tCO2e, −22% from the current policy baseline if forestland tax incentives are removed. Fifth, maintaining the existing tax policies in perpetuity incentivizes carbon sequestration levels equivalent to imposing a price of $70/tCO2e on the forest sector, highlighting the ecosystem service benefits of maintaining current tax policy. Finally, we estimate that current US forest tax policy provides about $8 billion/yr in climate change mitigation benefits by 2050. • We model the impact of current forest taxation policy on the U.S. timber sector. • Tax provisions incentivize management, conservation, and carbon sequestration. • U.S. forest carbon could be reduced by 22% if tax provisions are removed. • Current policy equates to a carbon price of $70/tCO 2 e without tax incentives. [ABSTRACT FROM AUTHOR]