Large-scale Forest Restoration Research Articles

Monitoring of areas in conflict with the Legislation for the Protection of Native Vegetation in Brazil: opportunity for large-scale forest restoration and for the Brazilian global agenda

Monitoring of areas in conflict with the Legislation for the Protection of Native Vegetation in Brazil: opportunity for large-scale forest restoration and for the Brazilian global agenda

Characteristics and Driving Mechanisms of Understory Vegetation Diversity Patterns in Central and Southern China

Large-scale forest restoration projects significantly reduce the net rates of forest loss. However, as a key component of forest restoration, planted forests have failed to restore biodiversity. China has implemented a large-scale afforestation program, which includes pure planted forests in particular, leading to various changes in ecosystem processes. Despite this, a comprehensive analysis of understory vegetation diversity patterns in these pure planted forests is still lacking. This study aimed to analyze the data on understory vegetation diversity from three typical pure and natural forest ecosystems of Hunan ecological forests to reveal their diversity patterns. The results revealed no significant difference in the understory diversity index between natural and pure forest types, although natural forests had a bigger species pool. The Zipf–Mandelbrot model was a better fit for species abundance distribution. The fitted results suggested that both environmental filtering and neutral processes affected the species abundance distribution and pure understory communities during restoration succession. Natural forests had the most stable understory diversity structure, whereas pure Phyllostachys heterocycla (Carr.) Mitford forests had the least stable structure. Multivariate regression tree analysis identified indicator species for each community. The gradient boosting model indicated that isothermality and slope direction were the most important factors affecting diversity. The β-diversity analysis showed that community establishment in the four forest types was affected via different mechanisms. The findings of this study have significant implications for understanding the impact of afforestation on the mechanisms for maintaining diversity.

Large-scale forest restoration generates comprehensive biodiversity gains in an Amazonian mining site

To reconcile environmental issues with socioeconomic development, the mitigation hierarchy emerges as a pivotal strategy that sequentially addresses environmental impacts through a structured approach of avoidance, minimization, remediation, and offsetting. No net loss (NNL) is achieved when biodiversity gains from all four mitigation stages are larger than the project's environmental impacts. Here, we assessed biodiversity changes linked to the implementation of the S11D Eliezer Batista iron mining Complex in the Carajás National Forest, Pará state, Brazil, expecting losses due to mining activities and gains through forest restoration offsets. We evaluated biodiversity stocks based on Biotic Value as the product of habitat importance and actual conditions. Habitat importance, a unique value for each class of land cover recognized within the study site, is based on the evaluation of habitat naturalness, rarity and endangerment, and substitutability. Actual conditions are computed from field-surveyed key ecological attributes of vegetation structure, community composition and diversity, and ecological processes, and forest restoration activities are able to restitute, within 4–6 years only, approximately 73 % of old-growth forest conditions. The Biotic Value ranges from 0 for mine lands to 1 for patchy savanna formations stocking above ironstone outcrops (locally known as cangas) and amounts to 0.43 units/ha for secondary forests. Between 2008 and 2021, we detected comprehensive land-use changes in the study area: Cangas, farmlands and old-growth forests decreased, while secondary forests and minelands increased considerably. Despite environmental degradation, the emergence of secondary forests contributed to a positive biodiversity balance within the areas managed by the mining company (+379 units), while biodiversity losses dominated outside the company's boundaries (−171 units). Although like-for-like compensation of canga impacts remains challenging, we thus conclude that forest restoration efforts initiated by the mining company effectively reversed the trajectory of environmental degradation prevailing in the landscape and provided considerable biodiversity gains for the region.

Understanding Community Participation in Tree Planting and Management in Deforested Areas in Cameroon's Western Highlands.

Deforestation and forest degradation continue to take place at alarming rates in Africa despite global net forest loss reductions. This is prompting large-scale forest restoration involving community volunteers to prevent, halt and reverse the loss of biodiversity for the sustainable development of forest landscapes in Africa. The study explored the motivations, challenges, barriers and negotiation strategies of community volunteers in ecosystem restoration and conservation initiatives in Cameroon's Western Highlands (Mount Bamboutos landscape), given that many such interventions are not achieving desired targets and goals. A total of 134 respondents involving farmers and local implementing NGO workers were interviewed, using semi-structured open-ended questionnaires. One focus group discussion was held with paramount traditional rulers to assess the strength, weaknesses, opportunities and threats (SWOT) of the community-led ecosystem restoration and conservation initiative. The principal components analysis with oblique (Direct oblimin) rotation was used to reduce the number of constitutive items in each dimension of motivation, challenge and barrier to community participation. Linear regression analysis was used to examine how the different dimensions of motivations, challenges and barriers influence community participation. Community participation was initially driven more by environmental motivations given the highly deforested and degraded Mount Bamboutos landscape, but later on driven more by economic and community motivations. Social factors were least expressed and non-significant predictors of participation. Community participation was primarily limited by management, financial, psychological, personal, and information challenges and barriers. Providing financial incentives to cover daily subsistence costs of food and transport was a key negotiation strategy that increased community participation. Conservation organisations should capitalise on environment, community and social motivational appeals during community education and awareness campaigns to increase voluntary community participation. The local knowledge on ecosystem restoration and conservation motivations, challenges, barriers, negotiation strategies, recommendations and SWOT analysis provide relevant baseline information for environment management decision-makers in Cameroon and other Sub-Saharan African countries.

Monitoring of large-scale forest restoration: Evidence of vegetation recovery and reversing chronic ecosystem degradation in the mountain region of Pakistan

Global ecosystem restoration efforts are aimed at climate change mitigation. In response to the challenge of global warming and supporting local adaptation, the Billion Tree Tsunami Afforestation Program (BTAP) was launched in 2014 to restore depleted forest ecosystems by extensive afforestation and/or reforestation in the Khyber Pakhtunkhwa Province of Pakistan. Under the BTAP, afforestation of all categories was carried out in an area of 300,000 ha, and 160 million plants were distributed under Farm Forestry and 4509 enclosures were established for Assisting Natural Regeneration (ANR) with the help of the local community. The present study evaluated historic deforestation trends using bi-temporal (1990–2010) change analysis and the performance of recent forest ecosystem restoration efforts based on time series analysis of stallite images. A total of 226 afforestation sites of the BTAP – Phase I were examined to determine the vegetation growth and evidence of ecosystem restoration efforts by regression and trend analysis of the annual normalized difference vegetation index (NDVI) composites from 2014 to 2021. The forest plantation and protected natural regeneration performance across the three key forest management regions of the Southern, Malakand and Northern zones remained variable, with growth values of 29%, 47% and 24%, respectively. The results suggest that the three forest regions lost 3.2% of the forest between 1990 and 2010. While accounting for most conservative figures validated from satellite data, the BTAP interventions during 2014–2018 improved the overall forest cover from 14.5% to 16.5% in these regions. The framework developed in this study and the derived results can help to formulate an evidence-based assessment of indicators for ecological restoration and nature-based solutions.

Ecosystem water use efficiency was enhanced by the implementation of forest conservation and restoration programs in China

The large-scale forest conservation and restoration programs (FCRPs) implemented in China have energetically promoted carbon sequestration and water consumption of terrestrial ecosystems. However, the impact of FCRPs on the coupling between them, that is, ecosystem water use efficiency (EWUE), remains unknown. Using the Mann-Kendall test and the Theil-Sen's slope estimator, we analyzed the EWUE trends of the FCRP-induced forest recovery zones (FFRZs) in the pre- and post-intensification phases of the programs. Then, the random quadrat comparison method was employed to compare the EWUE of FFRZs and that of their adjacent non-recovery zones (NRZs). We also performed partial correlation analysis and contribution analysis to investigate the response of EWUE to FCRP-induced forest recovery. Our study showed that the proportion of FFRZs presenting a significant increasing trend in EWUE expanded from 19.1% for the pre-intensification phase of FCRPs to 35.7% for the post-intensification phase. The EWUE of the FFRZs was significantly higher than that of their neighboring NRZs in arid and semi-arid regions whereas there was no significant difference between them in humid and semi-humid regions. EWUE was positively correlated with FCRP-induced tree cover in 74.6% of the FFRZs during the post-intensification phase of FCRPs. The average contribution of FCRP-induced forest recovery to EWUE change was 4.94 × 10-3 gC⋅mm−1⋅a-1 in the FFRZs, accounting for 39.1% of the total EWUE variation. We concluded that EWUE was significantly enhanced by the implementation of FCRPs in China. However, the EWUE increase could not be sustained by forest restoration in arid and semi-arid regions. Our study highlights that the implementation of FCRPs should pay more attention to the tradeoff between carbon sequestration and water consumption of ecosystems and be tailored to local conditions.

Assessing the Enabling Conditions for Translating Restoration Commitments to Restoration Actions: Case of Cameroon

Understanding governance and policy related conditions is relevant to determine what is needed to drive large-scale landscape restoration investments. Using Cameroon as a case study, this paper assessed the enabling conditions for large-scale forest restoration focusing on tree growing as the main practice. Descriptive statistics and correlation analysis were applied to understand trends in the opinions of 48 stakeholders sampled purposefully, including the review of forestry and land use related strategy and policy documents. Results indicated that stakeholders and strategy documents, strongly recognize the relevance of governance and policy related conditions to drive large-scale restoration. The trends in stakeholder insights revealed that the capacity of these conditions is currently weak and insufficient to enable large-scale restoration and progress towards improving these conditions have been very slow when compared to assessments made more than a decade ago. There is a need for a strong political will to improve these enabling conditions, though the technical arguments required to help guide and drive the political will are weak. The forest landscape restoration strategic framework needs to be revised and reinforced with appropriate and in-depth technical and operational orientations on how to improve each of the enabling conditions that will help achieve the large-scale restoration commitments in Cameroon.

Habitat amount is a driver for biodiversity, but not for the carbon stock in post-logging natural regenerating areas in Tropical Atlantic Forest

Natural regeneration has been considered an important strategy for improving large-scale forest restoration to revert the losses resulting from the fragmentation of tropical landscapes in recent years. However, local, regional, and spatial factors can influence the dynamics of regeneration, thereby affecting its efficiency. We investigated how time after disturbance, landscape characteristics, and climate gradients affect the efficiency of natural regeneration in the Brazilian Atlantic Forest. We searched for studies that addressed the post-logging regenerating of forests throughout the biome. For each included study, we extracted the forest age, species richness, and basal area (used as an estimate of carbon). Additionally, for each studied site (total 100 sites) we used land use maps to extract the landscape metrics and obtained bioclimatic variables from the global dataset. Further, we used forest age, landscape metrics, and bioclimatic variables to build models and predict forest species richness and carbon stock. Our results showed that species richness was positively affected by habitat amount (evaluated through patch area and perimeter-area ratio), isothermality, and forest age. Carbon stock was positively affected only by the forest age. These findings show that natural regeneration will yield the best results in terms of conserving the biodiversity among landscapes with a large number of habitats. Conversely, a landscape with a predominance of mature forest will be more efficient as carbon stock. We conclude that, when planning the restoration of large-scale landscapes, natural regeneration must be considered along with other strategies to ensure that multiple objectives are achieved.

Biochar and/or Compost to Enhance Nursery-Produced Seedling Performance: A Potential Tool for Forest Restoration Programs

Today, the use of nursery-produced seedlings is the most widely adopted method in forest restoration processes. To ensure and enhance the performance of transplanting seedlings into a specific area, soil amendments are often used due to their ability to improve soil physicochemical properties and, in turn, plant growth and development. The aim of the present study was to evaluate Populus euramericana growth and development on a growing substrate added with biochar and compost, both alone and in combination. To accomplish this aim, a pot experiment was performed to test biochar and/or compost effects on growing substrate physicochemical characteristics, plant morpho-physiological traits, and plant phenology. The results showed that biochar and/or compost improved growing substrate properties by increasing electrical conductivity, cation exchange capacity, and nutrient concentrations. On the one hand, these ameliorations accelerated poplar growth and development. On the other hand, amendments did not have positive effects on some plant morphological traits, although compost alone increased plant height, and very fine and fine root length. The combined use of biochar and compost did not show any synergistic or cumulative beneficial effects and led to a reduction in plant growth and development. In conclusion, compost alone seems to be the best solution in both ameliorating substrate characteristics and increasing plant growth, highlighting the great potential for its proper and effective application in large-scale forest restoration strategies.

LiDAR as a Tool for Assessing Change in Vertical Fuel Continuity Following Restoration

The need for fuel reduction treatments and the restoration of ecosystem resilience has become widespread in forest management given fuel accumulation across many forested landscapes and a growing risk of high-intensity wildfire. However, there has been little research on methods of assessing the effectiveness of those treatments at landscape scales. Most research has involved small-scale opportunistic case studies focused on incidents where wildland fires encountered recent restoration projects. It is important to assess whether restoration practices are successful at a landscape scale so improvements may be made as treatments are expanded and their individual effectiveness ages. This study used LiDAR acquisitions taken before and after a large-scale forest restoration project in the Malheur National Forest in eastern Oregon to broadly assess changes in fuel structure. The results showed some areas where treatments appeared effective, and other areas where treatments appeared less effective. While some aspects could be modified to improve accuracy, the methods investigated in this study offer forest managers a new option for evaluating the effectiveness of fuel reduction treatments in reducing potential damage due to wildland fire.

Forest restoration to promote a fair post COVID-19 recovery in the Brazilian Amazon

Forest restoration has attracted the attention of different organizations, investors, and donors with the launch of the UN Decade for Ecosystems Restoration (2021–2030), along with climate and biodiversity commitments. Restoration can address many of mankind's challenges, such as biodiversity loss, climate change, water security, and poverty. In the Brazilian Amazon, the ~28 million inhabitants are among the most vulnerable of the country, and this has only worsened during the COVID-19 pandemic. Meanwhile, millions of hectares are suitable for forest restoration. The growing demand for large-scale forest restoration projects have been prioritizing biophysical objectives (e.g., number of trees, hectares of land, and carbon) while it should be prioritizing the local people's well-being and a fair transition to a sustainable economy based on forest services' recovery. Nonetheless, many challenges need to be overcome to realize this potential. Amazonian states need to control illegality, enforce the existing policies and promote innovative ones to halt deforestation and enable large-scale restoration. Better governance and social engagement are urgently needed but depend upon, recognition of indigenous peoples and local communities' rights, needs, and knowledge. Forest restoration represents an opportunity for the emergence of a more inclusive development paradigm, much needed in the Amazon region, especially in the post COVID-19 world.

Landscape-scale forest restoration decreases vulnerability to drought mortality under climate change in southwest USA ponderosa forest

Drought-induced tree mortality is predicted to increase in dry forests across the globe as future projections show hotter, drier climates. This could potentially result in large-scale tree die-offs, changes in species composition, and loss of forest ecosystem services, including carbon storage. While some studies have found that forest stands with greater basal areas (BA) have higher drought mortality, many have not evaluated the extent to which forests restored to lower densities via restoration activities affect drought mortality. The southwestern USA is particularly susceptible to tree mortality due to the predicted increases in temperature, drier soils, and forests with high density. Our objective was to evaluate how ponderosa pine mortality is expected to be influenced by the Four Forests Restoration Initiative (4FRI), a large-scale forest restoration effort ongoing in northern Arizona, USA, that will reduce stand BA by approximately 40%. Specifically, we modeled drought mortality in three time periods, one contemporary (1970–2010), and two future (2020–2059 and 2060–2099) under three restoration scenarios: no thinning, 4FRI thinning, and a BA reduction beyond the 4FRI plan (4FRI-intensive). We estimated mortality using 11 climate models under two emissions scenarios. Without thinning, our model predicted that by mid-century (2020–2059), changes in climate could increase annual ponderosa pine mortality rates by 45–57% over contemporary rates. However, with thinning, mid-century mortality was predicted to remain near or below contemporary rates and these rates are 31–35% (4FRI) and 46–51% (4FRI-intensive) less than the mid-century scenarios without thinning. Our study shows that while climate change is likely to increase tree mortality rates, large-scale forest restoration projects, such as 4FRI, have the potential to ameliorate the effects of climate change and keep mortality rates near contemporary levels for decades.

Large-scale forest conservation and restoration programs significantly contributed to land surface greening in China

China has implemented a portfolio of large-scale forest conservation and restoration programs (FCRPs) to advance the sustainable management of forests. However, the contributions of these programs to forest recovery and land surface greening were generally evaluated on a local scale, which hindered the systematic planning of FCRPs. In this study, we analyzed the spatiotemporal patterns of tree cover (TC) change before and after the intensification of FCRPs using the Mann-Kendall test and the Theil–Sen slope estimator. With the improved phenology-based residual trend analysis (P-RESTREND) method, we derived the spatiotemporal patterns of human-induced tree cover (TCH) change on the national scale. Then, we calculated the effectiveness index of FCRPs at the provincial level, based on which the effectiveness levels for the 31 provinces of mainland China were classified. Our study showed that the area of forested lands with a significant greening trend was almost five times larger in the post-intensification phase (1999–2015) than in the pre-intensification phase of FCRPs (1982–1998). More than 29.9% of the forested lands were significantly improved in TC by human activities in the post-intensification phase. Provinces with high effectiveness levels were generally distributed in humid areas, whereas the majority of provinces with low and moderately low effectiveness levels were spread in arid and semi-arid regions. We concluded that the implementation of FCRPs had contributed greatly to the land surface greening in China. Moreover, the effectiveness of FCRPs in forest recovery was heterogeneous at the provincial level and was driven by multiple natural and socioeconomic factors.

Natural forest regrowth under different land use intensities and landscape configurations in the Brazilian Atlantic Forest

Natural forest regrowth is considered the most cost-effective strategy to promote large-scale forest restoration, but regrowth trajectories and their consequences for nature and people can be highly variable. This uncertainty may obstruct devoting land, time and resources in promoting this restoration approach. Process-based models allow to simulate forest regrowth under different scenarios and may thus support decision making to manage areas in ways that maximize forest restoration based on natural forest regrowth. In the present study, we used the process-based model LandClim to assess the following questions:1) How does land use intensity affect forest growth, aboveground biomass (AGB) and tree species diversity in agricultural landscapes in the long term? 2) How do different land use configurations affect the structure and expansion of second-growth forests? We based our study on six 4 × 4 km agricultural landscapes, dominated by pastures and sugarcane, in the Brazilian Atlantic Forest region. We parameterized and validated LandClim for the study region by comparing model outputs with published estimates and information from field data collected across the six landscapes. We then simulated natural forest regrowth under different land use intensities in the six landscapes and analyzed how land use intensity and landscape configuration affect AGB, tree species diversity and the spatial dynamics of second-growth forests. Our results showed negative effects of increased land use intensity on landscape biomass accumulation due to limited forest cover expansion. Landscapes dominated by sugarcane had lower forest regrowth potential than pasture-dominated landscapes due to lower likelihood of abandonment, and limited rates of seed availability and seedling growth. Land use intensity and landscape configuration were also important factors for tree diversity changes. However, temporal patterns differed, and while AGB reached a plateau after 100–150 years, tree diversity peaked between 30 and 70 years. Thus, the effects of land use intensity and landscape configuration on forest AGB and tree diversity take decades to be fully expressed, highlighting the importance of a long-term commitment in restoration projects.

A novel monitoring protocol to evaluate large-scale forest restoration projects in the tropics

A novel monitoring protocol to evaluate large-scale forest restoration projects in the tropics

Old-growth forest loss and secondary forest recovery across Amazonian countries

There is growing recognition of the potential of large-scale forest restoration in the Amazon as a ‘nature-based solution’ to climate change. However, our knowledge of forest loss and recovery beyond Brazil is limited, and carbon emissions and accumulation have not been estimated for the whole biome. Combining a 33 year land cover dataset with estimates of above-ground biomass and carbon sequestration rates, we evaluate forest loss and recovery across nine Amazonian countries and at a local scale. We also estimate the role of secondary forests in offsetting old-growth deforestation emissions and explore the temporal trends in forest loss and recovery. We find secondary forests across the biome to have offset just 9.7% of carbon emissions from old-growth deforestation, despite occupying 28.8% of deforested land. However, these numbers varied between countries ranging from 9.0% in Brazil to 23.8% in Guyana for carbon offsetting, and 24.8% in Brazil to 56.9% in Ecuador for forest area recovery. We reveal a strong, negative spatial relationship between old-growth forest loss and recovery by secondary forests, showing that regions with the greatest potential for large-scale restoration are also those that currently have the lowest recovery (e.g. Brazil dominates deforestation and emissions but has the lowest recovery). In addition, a temporal analysis of the regions that were >80% deforested in 1997 shows a continued decline in overall forest cover. Our findings identify three important challenges: (a) incentivising large-scale restoration in highly deforested regions, (b) protecting secondary forests without disadvantaging landowners who depend on farm-fallow systems, and (c) preventing further deforestation. Combatting all these successfully is essential to ensuring that the Amazon biome achieves its potential in mitigating anthropogenic climate change.

Integrating farmers’ decisions on the assessment of forest regeneration drivers in a rural landscape of Southeastern Brazil

Forest regeneration at large-scales is one of the main paths to achieving the ongoing ambitious restoration commitments. Thus, the identification of the main drivers of this process in agricultural landscapes is critical to understand the drivers determining restoration success. A growing number of studies have explored the biophysical and, less often, the socioeconomic drivers of forest regeneration using remote sensing approaches, but have not directly considered the influence of farmers’ decisions in spatial prediction models of forest regeneration. We explored the influence of biophysical and socioeconomic drivers on forest regeneration in a rural landscape of Southeastern Brazil, where native forest cover increased by 7.7%. We evaluated forest regeneration through the analysis of time series of multi-temporal satellite images and socioeconomic information obtained through a Social Survey with 47 landowners, using each farm as the study unit. Natural forest regeneration was mainly favored by lower land suitability for agriculture and higher proximity (lower distances) to forest remnants, as well by higher numbers of land-uses types in the farm and lower economic dependence of landowners from the farm income. Our results emphasize the importance of considering farmers’ decisions on predictive models of natural forest regeneration, which are critically needed to guide the implementation of large-scale forest restoration initiatives in agricultural landscapes.

Wood density variation in naturally regenerated stands of Pinus ponderosa in northern Arizona, USA

In the southwestern United States, land managers are implementing large-scale forest restoration projects involving treatments designed to improve forest health, protect ecosystem services, and reduce the risk of catastrophic wildfire in overstocked ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) forests. A better understanding of wood properties is necessary to improve the currently limited markets for the woody byproducts generated by these treatments. Therefore, our objective was to investigate variations in ponderosa pine wood density across the northern Arizona landscape. We sampled trees from 18 naturally regenerated stands and used X-ray densitometry to quantify the radial and axial variation within and among trees. We modeled within-stem wood density patterns using generalized additive models, and investigated the effects of climatic variation using response function analyses. Additionally, we tested the effects of site-level predictors on whole-tree wood density. We found high variability in radial wood density profiles among trees in our stands compared with that observed in studies of other species grown in plantations — perhaps due to high genetic variation within naturally regenerated stands. Wood density was negatively correlated with precipitation at annual and most quarterly intervals, except for a positive correlation with late-summer monsoon precipitation. The high wood density variation we found among trees highlights the need for further investigation of controls over wood properties in natural nonplantation forests.

An improved quality assessment framework to better inform large-scale forest restoration management

Dynamic monitoring of forest ecosystem quality is necessary for restoration program evaluation but remains challenging for very large-scale programs. Current evaluation methods employ regional forest quality indicators that compare the quality status of targeted forests with benchmarks from remnant old-growth forest communities, however data availability usually limits the application of available methods to small scales. We constructed an improved framework, integrating forest site classification selection and local remnant old-growth forest community delimitation, to quantify and map forest quality using environmental data and remote sensing (RS) based approaches. A classification strength model was introduced to improve the accuracy of forest site classification. The remote-sensing-based method integrates species composition and forest biological productivity characteristics recognition to develop a practical tool for large-scale remnant old-growth forest community delimitation. The new assessment framework was tested across the entire spatially heterogeneous Yangtze River Basin, the largest watershed in China and showed high accuracy in forest quality assessment based on observed field data validation. The forest site classification was selected by considering spatial heterogeneities in climate, topography and soil type, with 37 forest sites classified. The native forest community groups with less human disturbance in each forest site used for forest quality baseline estimation were also selected as forests with top 10% of biomass in protected areas. The case study demonstrated that forest areas of low and poor quality accounted for 34.46% of the total forest area in 2015. Between 2000 and 2015, 55.72% of forest areas experienced increases in quality level, and 7.07% experienced decreases. The improved forest quality assessment framework enhances the scope and accuracy of forest restoration information and can be applied as an evaluation tool for forest restoration management.

Structural Hurdles to Large-Scale Forest Restoration in the Brazilian Amazon

Structural Hurdles to Large-Scale Forest Restoration in the Brazilian Amazon