Resilient secondary tropical forests? Although deforestation is rampant across the tropics, fores... more Resilient secondary tropical forests? Although deforestation is rampant across the tropics, forest has a strong capacity to regrow on abandoned lands. These “secondary” forests may increasingly play important roles in biodiversity conservation, climate change mitigation, and landscape restoration. Poorter et al . analyzed the patterns of recovery in forest attributes (related to soil, plant functioning, structure, and diversity) in 77 secondary forest sites in the Americas and West Africa. They found that different attributes recovered at different rates, with soil recovering in less than a decade and species diversity and biomass recovering in little more than a century. The authors discuss how these findings can be applied in efforts to promote forest restoration. —AMS
Monitoring restored tropical forest diversity and structure through UAV-borne hyperspectral and lidar fusion
Remote Sensing of Environment, 2021
Abstract Remote sensors, onboard orbital platforms, aircraft, or unmanned aerial vehicles (UAVs) ... more Abstract Remote sensors, onboard orbital platforms, aircraft, or unmanned aerial vehicles (UAVs) have emerged as a promising technology to enhance our understanding of changes in ecosystem composition, structure, and function of forests, offering multi-scale monitoring of forest restoration. UAV systems can generate high-resolution images that provide accurate information on forest ecosystems to aid decision-making in restoration projects. However, UAV technological advances have outpaced practical application; thus, we explored combining UAV-borne lidar and hyperspectral data to evaluate the diversity and structure of restoration plantings. We developed novel analytical approaches to assess twelve 13-year-old restoration plots experimentally established with 20, 60 or 120 native tree species in the Brazilian Atlantic Forest. We assessed (1) the congruence and complementarity of lidar and hyperspectral-derived variables, (2) their ability to distinguish tree richness levels and (3) their ability to predict aboveground biomass (AGB). We analyzed three structural attributes derived from lidar data—canopy height, leaf area index (LAI), and understory LAI—and eighteen variables derived from hyperspectral data—15 vegetation indices (VIs), two components of the minimum noise fraction (related to spectral composition) and the spectral angle (related to spectral variability). We found that VIs were positively correlated with LAI for low LAI values, but stabilized for LAI greater than 2 m2/m2. LAI and structural VIs increased with increasing species richness, and hyperspectral variability was significantly related to species richness. While lidar-derived canopy height better predicted AGB than hyperspectral-derived VIs, it was the fusion of UAV-borne hyperspectral and lidar data that allowed effective co-monitoring of both forest structural attributes and tree diversity in restoration plantings. Furthermore, considering lidar and hyperspectral data together more broadly supported the expectations of biodiversity theory, showing that diversity enhanced biomass capture and canopy functional attributes in restoration. The use of UAV-borne remote sensors can play an essential role during the UN Decade of Ecosystem Restoration, which requires detailed forest monitoring on an unprecedented scale.
Corrigendum: Fostering natural forest regeneration on former agricultural land through economic and policy interventions (2020 Environ. Res. Lett. 15 043002)
Monitoring the structure of forest restoration plantations with a drone-lidar system
International Journal of Applied Earth Observation and Geoinformation, 2019
Abstract We are in an unprecedented moment for promoting forest restoration globally, with intern... more Abstract We are in an unprecedented moment for promoting forest restoration globally, with international and regional pledges to restore at least 350 million hectares by 2030. To achieve these ambitious goals, it is necessary to go beyond traditional plot-scale assessments and develop cost-effective technologies that can monitor the structure and function of restored forests at much broader scales. Lidar remote sensing in unmanned aerial vehicle (UAV) platforms can be an agile and autonomous method for monitoring forest restoration projects, especially under conditions when information updates are frequently needed in relatively small areas or, when using an airplane-borne lidar system may be not financially viable. Here, we explored the potential of an UAV-borne lidar system to assess the outcomes of a mixed-species restoration plantation experiment, designed to maximize aboveground biomass (AGB) accumulation. The experiment was established in Brazil’s Atlantic Forest, with 20 native tree species, by combining two levels of planting density and two management levels, totaling four treatment combinations and one control (plots left over for natural regeneration). We analyzed three structural variables from lidar data (canopy height, gap fraction and leaf area index) and one from field inventory data (AGB). Structural differences between the treatments and the control plots were reliably distinguished by the UAV-borne lidar system. AGB was strongly correlated with canopy height, allowing us to elaborate a predictive equation to use the UAV-borne lidar system for monitoring structural features in other restoration plantations in the region. UAV-borne lidar systems showed enormous potential for monitoring relatively broad-scale (thousands of hectares) forest restoration projects, providing an important tool to aid decision making and accountability in forest landscape restoration.
Look down—there is a gap—the need to include soil data in Atlantic Forest restoration
Restoration Ecology, 2018
Consideration of soil quality indicators is fundamental for understanding and managing ecosystems... more Consideration of soil quality indicators is fundamental for understanding and managing ecosystems. Despite the evidence regarding the importance of soil for provision of local and global ecosystem services, such as water regulation and carbon sequestration, soil remains an under‐investigated and undermined aspect of the environment. Here we evaluate to what extent soil indicators are taken into account in restoration. We focused on the Brazilian Atlantic Forest, a highly fragmented biome and a global biodiversity hotspot. We conducted a systematic literature review and we showed that the majority (59%) of the studies on restoration did not consider any soil indicator. Studies that demonstrated the importance of soil indicators most commonly reported soil pH (71%, n = 44), followed by potassium content (66%, n = 41) and phosphorus (64.5%, n = 40), while the least reported indicator was water retention (6.5%, n = 4). Only 40% of the retrieved studies included information about referen...
Philosophical Transactions of the Royal Society B: Biological Sciences
There has never been a more pressing and opportune time for science and practice to collaborate t... more There has never been a more pressing and opportune time for science and practice to collaborate towards restoration of the world's forests. Multiple uncertainties remain for achieving successful, long-term forest landscape restoration (FLR). In this article, we use expert knowledge and literature review to identify knowledge gaps that need closing to advance restoration practice, as an introduction to a landmark theme issue on FLR and the UN Decade on Ecosystem Restoration. Aligned with an Adaptive Management Cycle for FLR, we identify 15 essential science advances required to facilitate FLR success for nature and people. They highlight that the greatest science challenges lie in the conceptualization, planning and assessment stages of restoration, which require an evidence base for why, where and how to restore, at realistic scales. FLR and underlying sciences are complex, requiring spatially explicit approaches across disciplines and sectors, considering multiple objectives, d...
Proceedings of The Royal Society B: Biological Sciences, Dec 14, 2016
As society strives to transition towards more sustainable development pathways, it is important t... more As society strives to transition towards more sustainable development pathways, it is important to properly conceptualize the link between biodiversity (i.e. genes, traits, species and other dimensions) and human well-being (HWB; i.e. health, wealth, security and other dimensions). Here, we explore how published conceptual frameworks consider the extent to which the biodiversity -HWB links are being integrated into public discourse and scientific research and the implications of our findings for sustainable development. We find that our understanding has gradually evolved from seeing the value of biodiversity as an external commodity that may influence HWB to biodiversity as fundamental to HWB. Analysis of the literature trends indicates increasing engagement with the terms biodiversity, HWB and sustainable development in the public, science and policy spheres, but largely as independent rather than linked terms. We suggest that a consensus framework for sustainable development should include biodiversity explicitly as a suite of internal variables that both influence and are influenced by HWB. Doing so will enhance clarity and help shape coherent research and policy priorities. We further suggest that the absence of this link in development can inadvertently lead to a ratcheting down of biodiversity by otherwise well-meaning policies. Such biotic impoverishment could lock HWB at minimum levels or lead to its decline and halt or reverse progress in achieving sustainable development.
ABSTRACTSecondary tropical forests play an increasingly important role for carbon budgets and bio... more ABSTRACTSecondary tropical forests play an increasingly important role for carbon budgets and biodiversity conservation. Understanding successional trajectories is therefore imperative for guiding forest restoration and climate change mitigation efforts. Forest succession is driven by the demographic strategies – combinations of growth, mortality and recruitment rates – of the tree species in the community. However, our understanding of demographic diversity in tropical tree species stems almost exclusively from old-growth forests. Here, we assembled demographic information from repeated forest inventories along chronosequences in two wet (Costa Rica, Panama) and two dry (Mexico) Neotropical forests to assess whether the range of demographic strategies present in a community shifts across succession. We calculated demographic rates for >500 tree species while controlling for canopy status to compare demographic diversity in early successional (0-30 years), late successional (30-1...
We present the results of a hybrid research design that borrows from both experimental techniques... more We present the results of a hybrid research design that borrows from both experimental techniques—experimental games—and observational techniques—surveys—to examine the relationships between basic human values and exposure to natural ecosystems, on the one hand, and collective action for resource governance, on the other. We initially hypothesize that more frequent exposure to forests, and more pro-environmental values will be associated with more conservation action. However, we find that other values—tradition and conformity—are more important than pro-environmental values or exposure to nature. Our results imply that resource governance is likely to be more successful where resource users hold values that facilitate cooperation, not necessarily strong pro-environmental values.
Boletim do Museu Paraense Emílio Goeldi - Ciências Naturais, 2021
Após distúrbios antropogênicos ou naturais de larga escala, a regeneração de florestas tropicais ... more Após distúrbios antropogênicos ou naturais de larga escala, a regeneração de florestas tropicais segue uma progressão de estágios por meio dos quais os estágios florestais gradualmente aumentam a riqueza de espécies e a complexidade estrutural e funcional. Trajetórias sucessionais e taxas de mudanças sofrem ampla variação conforme a natureza do uso anterior da terra, a proximidade da floresta primária e a disponibilidade de fauna dispersora de sementes. As florestas regenerantes rapidamente acumulam nutrientes e carbono na vegetação, na serapilheira e no solo, mas a recuperação da composição de espécies pode levar séculos. As florestas tropicais em regeneração fornecem recursos e serviços ecossistêmicos essenciais que sustentam milhões de pessoas que dependem delas. Nos casos em que houve degradação do solo e as fontes de sementes são limitadas, estratégias de reflorestamento podem iniciar a sucessão da floresta e expandir a cobertura florestal. O reflorestamento requer um alinhamen...
Almost one-quarter of the world's land area has been degraded over the past 50 years because of s... more Almost one-quarter of the world's land area has been degraded over the past 50 years because of soil erosion, salinization, peatland and wetland drainage, and forest degradation. The resulting damage,
This study describes the 35-year progression of activities in the Pontal do Paranapanema region o... more This study describes the 35-year progression of activities in the Pontal do Paranapanema region of São Paulo State, Brazil. These activities began as a research project on the conservation ecology of the highly endangered Black Lion Tamarin and broadened into a landscape-scale restoration and conservation project involving the active participation of hundreds of landless families that colonized the region. Rather than viewing these colonists as a threat, a non-governmental organization arose to address their needs, providing training and support livelihoods. Local communities were engaged in conservation and restoration activities focused on studying the movement patterns of endangered species, environmental education programmes, planting native trees along riparian corridors, establishing coffee agroforestry plantings and initiating community-managed nurseries for the production of local native seedlings and non-native fruit trees. Farmers gained knowledge, income and food security...
Protecting biodiversity, either for its own sake or for its value to humanity, is a principal goa... more Protecting biodiversity, either for its own sake or for its value to humanity, is a principal goal of conservation efforts worldwide. For this reason, many studies on the social science of resource management and governance seek to quantify biodiversity outcomes. Here, we focus on the International Forestry Resources and Institutions program to demonstrate some of the challenges of quantitative biodiversity assessment and suggest ways to overcome them. One of this program's research goals is to understand the causes of biodiversity loss, which is explicitly assessed using plot-based forest sampling. Plot-based methods to capture biodiversity changes require huge amounts of data. Even if sampling is sufficient, existing protocols can only capture changes in the types of species actually sampled, typically trees. Other elements of biodiversity are not censused, including animals, herbs, shrubs, fungi, and epiphytes that may provide medicine, food, wildlife habitat, trade items, or cultural goods. Using case studies of two sites in Uganda, we demonstrate that more spatially extensive surveys targeting multiple types of data can give a broader picture of forest status and changes than can plot-based sampling alone; many relevant variables can be observed while traveling among plot points with little additional effort. Reviewing the ecological literature, we identify correlates of forest status that can supplement plot-based sampling. These include large trees, epiphyte-laden trees, culturally or commercially valuable species, large stumps, and evidence of hunting and trapping. Further, data elicited from local resource users can play an important role in biodiversity monitoring. These findings suggest that effective biodiversity monitoring may be within easier reach than previously thought, although robust comparisons among sites remains a challenge, especially when climate, soils, or site history differ greatly.
Reversing large-scale degradation and deforestation goes beyond what can be achieved by site-leve... more Reversing large-scale degradation and deforestation goes beyond what can be achieved by site-level ecological restoration. Forest and landscape restoration focuses on spatial scales beyond the ''site'' level, where multiple land uses and forms of land ownership coexist, and where management decisions are usually made by different sets of stakeholders. In this context, natural regeneration can be a cost-effective approach to expand buffer zones of protected areas or forest reserves, create new forest patches and riparian zones, and create biological corridors to link existing protected areas. Here, I describe different modalities of natural regeneration, describe their benefits and features, and present several case studies of large-scale natural regeneration. Regrowing forests are often ignored, and their ecological and economic value remains largely unrecognized. Effective incentives for landowners and local communities are needed to encourage and protect naturally regenerating forests on farms. Predicting and mapping areas with a high capacity for natural regeneration will lower the overall costs of implementing restoration at local, regional, and national levels and may permit larger areas to be restored. Regrowing tropical forests will play an increasingly important role in climate change mitigation and biodiversity conservation in our future uncertain world.
The carbon content and the specific gravity of wood are indirect indicators of carbon storage cap... more The carbon content and the specific gravity of wood are indirect indicators of carbon storage capacity of trees. We monitored carbon content in four tropical species (Apeiba tibourbou, Guatteria amplifolia, Hyeronima alchorneoides and Tetrathylacium macrophyllum) in four different succession stages (5-15 years, 15-30 years, 30-50 years and old-growth forest of approximately 80 years old) in humid lowland forests in Costa Rica's Osa Peninsula. Carbon content varied significantly, from 0.41 to 0.51, across species and across successional stages, but it was not affected by diameter at breast height in any species. Mean wood specific gravity varied 3-fold across species, from 0.18 (A. amplifolia) to 0.54 (H. alchorneoides), whereas carbon content ranged from 0.40 (A. amplifolia) to 0.51 (H. alchorneoides). Specific gravity varied significantly (from 0.41 to 0.55) across successional stages only in G. amplifolia, whereas carbon content was different in some successional stages in A. tibourbou, H. alchorneoides and T. macrophyllum. Specific gravity and carbon content were correlated only in T. macrophyllum. Finally, results suggest that carbon content pertains to each species and it is affected by the succession stage.
Regrowing natural forests is a prominent natural climate solution, but accurate assessments of it... more Regrowing natural forests is a prominent natural climate solution, but accurate assessments of its potential are limited by uncertainty and variability around carbon accumulation rates. To assess why and where rates differ, we compiled 13,112 georeferenced measurements of carbon accumulation. Climate explained variation in rates better than land use history, so we combined field data with 66 environmental covariate layers to create a global, 1-km resolution map of potential aboveground carbon accumulation rates for the first 30 years of forest regrowth. Our results indicate that on average default forest regrowth rates from the Intergovernmental Panel on Climate Change are underestimated by 32% and miss 8-fold variation within ecozones. Conversely, we conclude that previously reported maximum climate mitigation potential from natural forest regrowth is overestimated by 11% due to the use of overly high rates. Our results therefore provide a much needed and globally consistent method for assessing natural forest regrowth as a climate mitigation strategy. To constrain global warming, we must reduce emissions and capture excess carbon dioxide (CO2) in the atmosphere 1,2 . Restoring forest cover, defined here as the transition from < 25% tree cover to > 25% tree cover where forests historically occurred, is a promising option for additional carbon capture 3 and has been prioritized in many national and international goals 4,5 . It is deployable, scalable, and provides important biodiversity and ecosystem services 6 . Yet the magnitude and distribution of climate mitigation opportunity from restoring forest cover is poorly described, with large confidence intervals around estimates 2,3 . To evaluate the appropriateness of forest cover restoration for climate mitigation, compared to the multitude of other potential climate mitigation actions, countries, corporations, and multilateral entities need more accurate assessments of its potential 7 . Mitigation potential from restoring forest cover (reported here in terms of MgCO2 yr -1 ) is determined by the potential extent and location of new forest ("area of opportunity") and the rate at which those forests remove atmospheric CO2 (reported here in terms of MgC ha -1 yr -1 ). While there are now multiple estimates of area of opportunity based on diverse and often heavily debated criteria (e.g., references 3,8-11 ), we lack spatially explicit and globally comprehensive estimates of accumulation rates. This is especially true for natural forest regrowth, defined here as the recovery of forest cover on deforested lands through spontaneous regrowth after cessation of prior disturbance or land use. Many countries do not have nationally specific forest carbon accumulation rates and instead rely on default rates from the Intergovernmental Panel on Climate Change (IPCC) . Although these rates were recently updated , they nonetheless represent coarse estimates based on continent and ecological zone, and do not account for finer scale variation in rates due to more local land use history or environmental conditions. We focus here on natural forest regrowth for several reasons, but there are many ways to restore forest or tree cover (Table ) and all have value in specific contexts. Natural forest regrowth can cost less than intensive tree planting and also promote re-establishment of local biodiversity . Reliance on natural forest regrowth, coupled with maintenance of natural disturbance regimes, also avoids perverse tree establishment in native grasslands . Some reviews further suggest that naturally regrowing forests can recover as well as or better than actively restored forests . However these reviews are likely biased towards more amenable sites for forest establishment and natural forest regrowth can be limited due to severe land degradation and/or distant seed sources 21 . Our comprehensive analysis across a range of starting conditions therefore provides a robust baseline for natural forest regrowth, elucidating fundamental constraints and drivers of carbon accumulation rates, and serving as a benchmark for alternative approaches to restoring forest cover.
Philosophical Transactions of the Royal Society B: Biological Sciences
Community involvement is critical for the success of many interventions designed to promote refor... more Community involvement is critical for the success of many interventions designed to promote reforestation. To secure this involvement, it helps to recognize that communities are heterogenous both within and among themselves and possess diverse mixes of livelihood assets required to implement reforestation. We explore the relationship between livelihood assets and reforestation success and outline a conceptual model that we call the community capacity curve (CCC) applied to reforestation. We argue that the shape of the CCC is sigmoidal. Importantly, communities at the lower end of the CCC have limited capacity to implement reforestation projects without substantial and ongoing capacity building and other sorts of support, including through livelihood projects that improve food security and provide cash benefits. Communities at the higher part of the CCC have greater capacity to implement reforestation projects, especially projects focused on biodiversity and environmental services. T...
Uploads
Papers by Robin Chazdon