United States Agency for International Development

▶ Addresses a wide range of timely environment, economic and energy topics ▶ A forum to review, analyze and stimulate the development, testing and implementation of mitigation and adaptation strategies at regional, national and global scales ▶ Contributes to real-time policy analysis and development as national and international policies and agreements are discussed and promulgated ▶ 94% of authors who answered a survey reported that they would definitely publish or probably publish in the journal again

Mitigation and Adaptation Strategies for Global Change

Framework Convention on Climate Change

Better stewardship of land is needed to achieve the Paris Climate Agreement goal of holding warming to below 2 °C; however, confusion persists about the specific set of land stewardship options available and their mitigation potential. To address this, we identify and quantify "natural climate solutions" (NCS): 20 conservation, restoration, and improved land management actions that increase carbon storage and/or avoid greenhouse gas emissions across global forests, wetlands, grasslands, and agricultural lands. We find that the maximum potential of NCS-when constrained by food security, fiber security, and biodiversity conservation-is 23.8 petagrams of CO2 equivalent (PgCO2e) y-1 (95% CI 20.3-37.4). This is ≥30% higher than prior estimates, which did not include the full range of options and safeguards considered here. About half of this maximum (11.3 PgCO2e y-1) represents cost-effective climate mitigation, assuming the social cost of CO2 pollution is ≥100 USD MgCO2e-1 by 2030. Natural climate solutions can provide 37% of cost-effective CO2 mitigation needed through 2030 for a >66% chance of holding warming to below 2 °C. One-third of this cost-effective NCS mitigation can be delivered at or below 10 USD MgCO2-1 Most NCS actions-if effectively implemented-also offer water filtration, flood buffering, soil health, biodiversity habitat, and enhanced climate resilience. Work remains to better constrain uncertainty of NCS mitigation estimates. Nevertheless, existing knowledge reported here provides a robust basis for immediate global action to improve ecosystem stewardship as a major solution to climate change.

https://www.pnas.org/content/pnas/114/44/11645.full.pdf

Natural climate solutions

Social learning is increasingly becoming a normative goal in natural resource management and policy. However, there remains little consensus over its meaning or theoretical basis. There are still considerable differences in understanding of the concept in the literature, including a number of articles published in Ecology & Society. Social learning is often conflated with other concepts such as participation and proenvironmental behavior, and there is often little distinction made between individual and wider social learning. Many unsubstantiated claims for social learning exist, and there is frequently confusion between the concept itself and its potential outcomes. This lack of conceptual clarity has limited our capacity to assess whether social learning has occurred, and if so, what kind of learning has taken place, to what extent, between whom, when, and how. This response attempts to provide greater clarity on the conceptual basis for social learning. We argue that to be considered social learning, a process must: (1) demonstrate that a change in understanding has taken place in the individuals involved; (2) demonstrate that this change goes beyond the individual and becomes situated within wider social units or communities of practice; and (3) occur through social interactions and processes between actors within a social network. A clearer picture of what we mean by social learning could enhance our ability to critically evaluate outcomes and better understand the processes through which social learning occurs. In this way, it may be possible to better facilitate the desired outcomes of social learning processes.

/pdf/what-is-social-learning-52x38zo69h.pdf

What is social learning

Most tropical forests outside protected areas have been or will be selectively logged so it is essential to maximize the conservation values of partially harvested areas. Here we examine the extent to which these forests sustain timber production, retain species, and conserve carbon stocks. We then describe some improvements in tropical forestry and how their implementation can be promoted. A simple meta-analysis based on >100 publications revealed substantial variability but that: timber yields decline by about 46% after the first harvest but are subsequently sustained at that level; 76% of carbon is retained in once-logged forests; and, 85‐100% of species of mammals, birds, invertebrates, and plants remain after logging. Timber stocks will not regain primary-forest levels within current harvest cycles, but yields increase if collateral damage is reduced and silvicultural treatments are applied. Given that selectively logged forests retain substantial biodiversity, carbon, and timber stocks, this “middle way” between deforestation and total protection deserves more attention from researchers, conservation organizations, and policy-makers. Improvements in forest management are now likely if synergies are enhanced among initiatives to retain forest carbon stocks (REDD+), assure the legality of forest products, certify responsible management, and devolve control over forests to empowered local communities.

/pdf/sustaining-conservation-values-in-selectively-logged-1olkbzv6lh.pdf

Sustaining conservation values in selectively logged tropical forests: the attained and the attainable

Global concern over rising atmospheric concentrations of carbon dioxide is stimulating development and implementation of policies aimed at reducing net greenhouse gas emissions by enhancing carbon sinks. One option for reducing net emissions is to lessen damage to residual forests during selective logging, thereby retaining additional carbon in biomass. A pilot carbon offset project was initiated in Sabah, Malaysia, in 1992 in which a power company provided funds to a timber concessionaire to implement guidelines aimed at reducing logging damage; in doing so, the utility gained potential credit towards future emissions reduction requirements. To quantify the carbon retained due to this effort, we compared dipterocarp forests logged according to reduced-impact logging guidelines with forests logged by conventional methods in terms of the above- and below-ground biomass both before and after logging. Prior to logging, the forest stored approximately 400 Mg biomass ha-1, 17 percent of which was belowground. High volumes of timber were removed from both of the logging areas (mean CNV = 154, RIL = 104 m3ha-'). Forty-one percent of the unharvested trees <60 cm DBH were severely damaged (uprooted and crushed) from logging in conventional logging areas in contrast to 15 percent in reduced-impact logging areas. Approximately 18 and 12 percent, respectively, of the remaining residual trees in conventional and reduced-impact logging areas suffered less severe damage (e.g., crown or bark damage). Mortality rates of the less severely damaged trees in all DBH classes were higher during the first year in conventional logging areas than in reduced-impact logging areas. One yr post harvest, conventional and reduced-impact logging areas contained biomass equivalent to about 44 percent and 67 percent of pre-logging levels, respectively. Approximately 62 percent of the difference in carbon retention was due to fewer trees killed in the reduced-impact logging areas; the remaining 38 percent was due to a lower mass of branches, stumps and waste wood from felled trees in reduced-impact logging areas. Mortality of damaged trees in both areas may contribute to net decreases in biomass for several years after logging. More and larger trees remained undamaged where reducedimpact logging was practiced, hence future biomass increment and yields of marketable timber are expected to be greater in the reduced-impact logging areas than in conventional logging areas.

Retaining Forest Biomass By Reducing Logging Damage

Using reduced-impact timber-harvesting practices in legally logged tropical forests would reduce global carbon emissions by 016 Gt/year at a modest cost and with little risk of "leakage" (increased carbon emissions elsewhere)

https://journals.plos.org/plosbiology/article/file?id=10.1371/journal.pbio.0060166&type=printable

Improved tropical forest management for carbon retention

Soil disturbance and post-logging forest recovery on bulldozer paths in Sabah, Malaysia

To understand how tropical ecosystems function we need to appreciate not only what plants, animals and microbes they contain, but how they interact with each other. This volume synthesizes the current state of knowledge of tropical biotic interaction, with chapters providing reviews or case studies drawn from research conducted in both Old and New World tropics, including interactions among taxa at all levels. An underlying theme of the volume is revealing the importance of the maintenance of high diversity in tropical regions.

Michelle A. Pinard

Papers

Sustaining conservation values in selectively logged tropical forests: the attained and the attainable

Retaining Forest Biomass By Reducing Logging Damage

Improved tropical forest management for carbon retention

Soil disturbance and post-logging forest recovery on bulldozer paths in Sabah, Malaysia

Biotic Interactions in the Tropics: Their Role in the Maintenance of Species Diversity