Leaf size varies by over a 100,000-fold among species worldwide. Although 19th-century plant geographers noted that the wet tropics harbor plants with exceptionally large leaves, the latitudinal gradient of leaf size has not been well quantified nor the key climatic drivers convincingly identified. Here, we characterize worldwide patterns in leaf size. Large-leaved species predominate in wet, hot, sunny environments; small-leaved species typify hot, sunny environments only in arid conditions; small leaves are also found in high latitudes and elevations. By modeling the balance of leaf energy inputs and outputs, we show that daytime and nighttime leaf-to-air temperature differences are key to geographic gradients in leaf size. This knowledge can enrich "next-generation" vegetation models in which leaf temperature and water use during photosynthesis play key roles.

a b s t r a c tNumerous assessments have quantified, mapped, and valued the services provided by ecosystems that are important for human wellbeing. However, much of the literature does not clarify how the information gathered in such assessments could be used to inform decisions that will impact ecosystem services. We propose that the process of making management decisions for ecosystem services comprises five core steps: identification of the problem and its social-ecological context; specification of objectives and associated performance measures; defining alternative management actions and evaluating the consequences of these actions; assessment of trade-offs and prioritization of alternative management actions; and making management decisions. We synthesize the degree to which the peer-reviewed ecosystem services literature has captured these steps. For the ecosystem service paradigm to gain traction in science and policy arenas, future ecosystem service assessments should have clearly articulated objectives, seek to evaluate the consequences of alternative management actions, and facilitate closer engagement between scientists and stakeholders.

There is an urgent need to improve the evaluation of conservation interventions. This requires specifying an objective and a frame of reference from which to measure performance. Reference frames can be baselines (i.e., known biodiversity at a fixed point in history) or counterfactuals (i.e., a scenario that would have occurred without the intervention). Biodiversity offsets are interventions with the objective of no net loss of biodiversity (NNL). We used biodiversity offsets to analyze the effects of the choice of reference frame on whether interventions met stated objectives. We developed 2 models to investigate the implications of setting different frames of reference in regions subject to various biodiversity trends and anthropogenic impacts. First, a general analytic model evaluated offsets against a range of baseline and counterfactual specifications. Second, a simulation model then replicated these results with a complex real world case study: native grassland offsets in Melbourne, Australia. Both models showed that achieving NNL depended upon the interaction between reference frame and background biodiversity trends. With a baseline, offsets were less likely to achieve NNL where biodiversity was decreasing than where biodiversity was stable or increasing. With a no-development counterfactual, however, NNL was achievable only where biodiversity was declining. Otherwise, preventing development was better for biodiversity. Uncertainty about compliance was a stronger determinant of success than uncertainty in underlying biodiversity trends. When only development and offset locations were considered, offsets sometimes resulted in NNL, but not across an entire region. Choice of reference frame determined feasibility and effort required to attain objectives when designing and evaluating biodiversity offset schemes. We argue the choice is thus of fundamental importance for conservation policy. Our results shed light on situations in which biodiversity offsets may be an inappropriate policy instrument Importancia de la Especificación de Línea de Base en la Evaluación de Intervenciones de Conservación y la Obtención de Ninguna Pérdida Neta de la Biodiversidad

Background: Conservation decisions not only impact wildlife, habitat, and environmental health, but also human wellbeing and social justice. The inclusion of safeguards and equity considerations in the conservation field has increasingly garnered attention in international policy processes and amongst conservation practitioners. Yet, what constitutes an 'equitable' solution can take many forms, and how the concept is treated within conservation research is not standardized. This review explores how social equity is conceptualized and assessed in conservation research.Methods/Design: Using a structured search and screening process, we identified 138 peer-reviewed studies that addressed equity in relation to conservation actions. The authors developed a coding framework to guide the review process, focusing on the current state of, definitions used for, and means of assessing social equity in empirical conservation research.Review Results: Results show that empirical research on social equity in conservation is rapidly growing, with the majority of studies on the topic published only since 2009. Equity within conservation research is skewed toward distributional concerns and to a lesser extent procedural issues, with recognition and contextual equity receiving little attention. Studies are primarily situated in forested biomes of the Global South. Conservation interventions mostly resulted in mixed or negative impacts on equity.Synthesis and Discussion: Our results demonstrate the current limitations of research on equity in conservation, and raise challenging questions about the social impacts of conservation and how to ameliorate equity concerns. Framing of equity within conservation research would benefit from greater transparency of study motivation, more explicit definition of how equity is used within the study context, and consideration for how best to assess it. We recommend that the empirical conservation literature more deeply engage with different notions of equity when studying, planning, and implementing actions to address potential trade-offs among equity and conservation objectives and beneficiaries.

Palm oil producing countries regularly promote the positive impact of palm oil agriculture on poverty alleviation, despite limited evidence about the contribution of this crop on village well-being. Past evaluations that quantify the social impact of oil palm are dominated by localized studies, which complicate the detection of generalizable findings. Moreover, only a few of these evaluations are based on rigorous case-control studies, which limits the robustness of the conclusions. Here we examined the association between the development of oil palm plantations and change in objective or material wellbeing between 2000 and 2014 across villages in Kalimantan, Indonesian Borneo. We applied a matching method to evaluate the impacts of oil palm plantations across different aspects of well-being, accounting for varying time delays in the accrual and realization of benefits after plantation development. Our study reveals that the social impacts of oil-palm plantations are not uniformly positive, nor negative, and have varied systematically with biophysical locations and baseline socioeconomic conditions of nearby communities prior to oil palm development. Plantations developed in villages with low to moderate forest cover, in which the majority of communities already relied on market-oriented livelihoods, were associated with improved socioeconomic well-being compared to villages without oil palm development. However, we found the opposite for plantations developed in remote villages with higher forest cover, in which the majority of communities previously relied on subsistence-based livelihoods. Overall, oil palm growing villages were more associated with reduced rate of improvement of social and environmental well-being compared to villages without oil palm development, regardless of location and baseline community livelihoods. Our findings highlight an urgent need for careful evaluation and planning in the development of oil palm agriculture in remote forested areas. For oil palm regions that have been developed, our study shows that unsustainable livelihoods, increased socioeconomic disparity, and environmental issues remain major challenges.

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Conservation decisions increasingly involve multiple environmental and social objectives, which result in complex decision contexts with high potential for trade-offs. Improving social equity is one such objective that is often considered an enabler of successful outcomes and a virtuous ideal in itself. Despite its idealized importance in conservation policy, social equity is often highly simplified or ill-defined and is applied uncritically. What constitutes equitable outcomes and processes is highly normative and subject to ethical deliberation. Different ethical frameworks may lead to different conceptions of equity through alternative perspectives of what is good or right. This can lead to different and potentially conflicting equity objectives in practice. We promote a more transparent, nuanced, and pluralistic conceptualization of equity in conservation decision making that particularly recognizes where multidimensional equity objectives may conflict. To help identify and mitigate ethical conflicts and avoid cases of good intentions producing bad outcomes, we encourage a more analytical incorporation of equity into conservation decision making particularly during mechanistic integration of equity objectives. We recommend that in conservation planning motivations and objectives for equity be made explicit within the problem context, methods used to incorporate equity objectives be applied with respect to stated objectives, and, should objectives dictate, evaluation of equity outcomes and adaptation of strategies be employed during policy implementation.

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