Paula Meli

Restoration enhances wetland biodiversity and ecosystem service supply, but results are context-dependent: a meta-analysis.

Wetlands are valuable ecosystems because they harbor a huge biodiversity and provide key services to societies. When natural or human factors degrade wetlands, ecological restoration is often carried out to recover biodiversity and ecosystem services (ES). Although such restorations are routinely performed, we lack systematic, evidence-based assessments of their effectiveness on the recovery of biodiversity and ES. Here we performed a meta-analysis of 70 experimental studies in order to assess the effectiveness of ecological restoration and identify what factors affect it. We compared selected ecosystem performance variables between degraded and restored wetlands and between restored and natural wetlands using response ratios and random-effects categorical modeling. We assessed how context factors such as ecosystem type, main agent of degradation, restoration action, experimental design, and restoration age influenced post-restoration biodiversity and ES. Biodiversity showed excellent recovery, though the precise recovery depended strongly on the type of organisms involved. Restored wetlands showed 36% higher levels of provisioning, regulating and supporting ES than did degraded wetlands. In fact, wetlands showed levels of provisioning and cultural ES similar to those of natural wetlands; however, their levels of supporting and regulating ES were, respectively, 16% and 22% lower than in natural wetlands. Recovery of biodiversity and of ES were positively correlated, indicating a win-win restoration outcome. The extent to which restoration increased biodiversity and ES in degraded wetlands depended primarily on the main agent of degradation, restoration actions, experimental design, and ecosystem type. In contrast, the choice of specific restoration actions alone explained most differences between restored and natural wetlands. These results highlight the importance of comprehensive, multi-factorial assessment to determine the ecological status of degraded, restored and natural wetlands and thereby evaluate the effectiveness of ecological restorations. Future research on wetland restoration should also seek to identify which restoration actions work best for specific habitats.

Ecosystem response to interventions: lessons from restored and created wetland ecosystems

Summary Current efforts to restore and create ecosystems require greater understanding of ecosystems’ responses to commonly used physical and biological intervention approaches to overcome ecological and technological limitations. We estimated effect sizes from measurements of biotic assemblage structure and biogeochemical functions at 628 restored and created wetlands globally, in comparison with 499 reference wetlands. We studied the recovery trajectories of wetlands where different restoration or creation approaches were used under different environmental settings. Although the variance explained by a linear mixed-effects models was low (6–7%), the study of recovery trajectories showed that the restoration or creation approach had no significant effects in most environmental settings. In particular, wetlands where surface modification and flow re-establishment were used followed similar recovery trajectories regardless of whether they were revegetated or not. We even found potential detrimental effects of biological manipulations on the recovery of the plant assemblage, particularly in cold climates and in wetlands restored or created in agricultural areas. Since physical interventions are required to recover or create the hydrological conditions of degraded or new wetlands, and given the high cost (22–73%) of biological interventions (i.e. revegetation), the need for biological interventions is, in most cases, unclear. Our results highlight the urgent need to increase our understanding of the long-term effects of restoration and creation actions in our aim to engage in large-scale ecosystem management strategies for wetlands. Synthesis and applications. These results suggest that, currently, the recovery and development processes of restored and created wetlands can be driven by spontaneous processes rather than by the response of wetlands to human interventions other than those targeted to restore hydrological conditions that existed prior to disturbance. However, given the synthetic nature of the data set, the mixed nature of available data and the limited number of measures we found to estimate recovery, caution must be exercised when adapting the results presented here to the planning and execution of specific ecosystem restoration projects.

A global review of past land use, climate, and active vs. passive restoration effects on forest recovery

Global forest restoration targets have been set, yet policy makers and land managers lack guiding principles on how to invest limited resources to achieve them. We conducted a meta-analysis of 166 studies in naturally regenerating and actively restored forests worldwide to answer: (1) To what extent do floral and faunal abundance and diversity and biogeochemical functions recover? (2) Does recovery vary as a function of past land use, time since restoration, forest region, or precipitation? (3) Does active restoration result in more complete or faster recovery than passive restoration? Overall, forests showed a high level of recovery, but the time to recovery depended on the metric type measured, past land use, and region. Abundance recovered quickly and completely, whereas diversity recovered slower in tropical than in temperate forests. Biogeochemical functions recovered more slowly after agriculture than after logging or mining. Formerly logged sites were mostly passively restored and generally recovered quickly. Mined sites were nearly always actively restored using a combination of planting and either soil amendments or recontouring topography, which resulted in rapid recovery of the metrics evaluated. Actively restoring former agricultural land, primarily by planting trees, did not result in consistently faster or more complete recovery than passively restored sites. Our results suggest that simply ending the land use is sufficient for forests to recover in many cases, but more studies are needed that directly compare the value added of active versus passive restoration strategies in the same system. Investments in active restoration should be evaluated relative to the past land use, the natural resilience of the system, and the specific objectives of each project.

Restoration and repair of Earth's damaged ecosystems

Given that few ecosystems on the Earth have been unaffected by humans, restoring them holds great promise for stemming the biodiversity crisis and ensuring ecosystem services are provided to humanity. Nonetheless, few studies have documented the recovery of ecosystems globally or the rates at which ecosystems recover. Even fewer have addressed the added benefit of actively restoring ecosystems versus allowing them to recover without human intervention following the cessation of a disturbance. Our meta-analysis of 400 studies worldwide that document recovery from large-scale disturbances, such as oil spills, agriculture and logging, suggests that though ecosystems are progressing towards recovery following disturbances, they rarely recover completely. This result reinforces conservation of intact ecosystems as a key strategy for protecting biodiversity. Recovery rates slowed down with time since the disturbance ended, suggesting that the final stages of recovery are the most challenging to achieve. Active restoration did not result in faster or more complete recovery than simply ending the disturbances ecosystems face. Our results on the added benefit of restoration must be interpreted cautiously, because few studies directly compared different restoration actions in the same location after the same disturbance. The lack of consistent value added of active restoration following disturbance suggests that passive recovery should be considered as a first option; if recovery is slow, then active restoration actions should be better tailored to overcome specific obstacles to recovery and achieve restoration goals. We call for a more strategic investment of limited restoration resources into innovative collaborative efforts between scientists, local communities and practitioners to develop restoration techniques that are ecologically, economically and socially viable.

Social Perceptions of Rainforest and Climatic Change from Rural Communities in Southern Mexico

Understanding social perceptions of rural communities is essential to construct public policy and management alternatives, not only to maintain natural ecosystems but also to deal with a changing environment due to climatic change. Because climate variability in Mexico has important socio-economic and environmental impacts, it is necessary to build capacities for adaptation. We describe social perceptions of three main local stakeholders (that is, farmers, elders, and local authorities), regarding their relationships with rainforest and local adaptation to climate change in eleven rural communities in Marqués de Comillas municipality, Chiapas, Southern Mexico. We based in a qualitative approach and used participant observation and semi-structured interviews. Even certain subtly variation among stakeholders, we recognized some underlying ideas behind perceptions. Rainforest is considered crucial to maintain human livelihoods and to mitigate climatic changes. They perceived changes in climate occurring in the region, such as raising temperature, unpredictable rainfall, and streams becoming dry. Local organization and government involved in managing rainforest or dealing with climatic changes are practically absent. This emphasizes the needs bring proper and reliable information to make decisions regarding rainforest use and management, but also to adapt to a changing climate. The loss of the collective character of the communities and, certain conflicts in public policies that mirrored in the coexistence of initiatives with contrasting objectives are proposed as particularly important for understanding the emergence of these perceptions. We proposed some recommendations to bolster regional capacities addressing climate change. Involving stakeholders such as governmental and non-governmental institutions is also imperative.

Lecciones de cuatro meta-análisis globales sobre la restauración de la biodiversidad y los servicios ecosistémicos

La restauracion ecologica se utiliza a menudo para recuperar los niveles de biodiversidad y de servicios ecosistemicos (SE) en ecosistemas degradados. En general, los resultados de la restauracion ecologica se pueden estimar como el progreso o la complecion de la recuperacion de indicadores de la integridad ecologica en el estado restaurado respecto al estado degradado o de referencia, respectivamente. Presentamos una sintesis de estos resultados segun cuatro meta-analisis globales independientes, obtenidos en una amplia gama de ecosistemas, con enfasis en humedales, agroecosistemas y bosques. La restauracion ecologica aumento la biodiversidad y los SE en 58 y 99%, respectivamente. Sin embargo, estos niveles fueron inferiores a los de los ecosistemas de referencia (-10 y -8%, respectivamente). La recuperacion vario entre tipos de ecosistema. Los humedales restaurados tuvieron niveles mas altos de biodiversidad y de SE (19 y 43%, respectivamente) en relacion a los degradados, aunque los niveles de los SE fueron inferiores (-13%) a los de referencia. La restauracion aumento los niveles de biodiversidad, SE de soporte y SE de regulacion de los agroecosistemas en 68, 42 y 120%, respectivamente, y los agroecosistemas restaurados tuvieron niveles de biodiversidad y de estos SE similares a los ecosistemas de referencia. En el caso de los bosques, la recuperacion fue completa para todos los SE, mientras que la biodiversidad, aunque aumento 106% despues de la restauracion, fue 21% inferior a los niveles de referencia. Existe un hueco en la literatura cientifica sobre la evaluacion cuantitativa de los SE culturales en ecosistemas restaurados. La recuperacion de la biodiversidad y de los SE se correlacionaron de forma positiva en las comparaciones de ecosistemas degradados y restaurados en todos los meta-analisis. Concluimos que la restauracion ecologica aumenta de forma notable la biodiversidad y los SE, aunque no se alcanzan los niveles de los ecosistemas de referencia, y que la efectividad depende, en gran medida, del contexto. https://doi.org/10.25260/EA.17.27.1.1.252