Secondary forests offset less than 10% of deforestation-mediated carbon emissions in the Brazilian Amazon

Regeneration of secondary forest following anthropogenic disturbance from 1985 to 2021 for Amazonas, Brazil

Following old-growth forest loss and subsequent land abandonment, secondary forest grows throughout the Amazon biome. For Amazonas, agricultural colonization was unsuccessful in many regions, leading to the regeneration of secondary forest and carbon storage under favorable climate conditions. Herein, the extent of regeneration in Amazonas and its timescale are investigated, including a granular analysis of its 62 municipalities, based on the MapBiomas dataset from 1985 to 2021. By 2021, 10,495 km2 of secondary forest had grown, corresponding to 28% of the lost old-growth forest. After normalization for algorithmic differences, this estimate was 17%-38% lower than prior studies for Amazonas that used earlier versions of the MapBiomas dataset, indicating increased accuracy in landcover assignments for more current versions of the dataset. For the northeastern microregion, representing the 15 municipalities of economic and population dominance in Amazonas, the growth of secondary forest varied from 3.0% to 9.8% of the total land area. For the southern microregion, constituting seven municipalities adjacent to large-scale deforestation of Mato Grosso and Rondônia, regeneration of secondary forest constituted 0.4%-1.2% of the land area. For the remaining interior municipalities, the regeneration was 0.0%-1.9%. Among the municipalities, the median regeneration interval, corresponding to the duration between the loss of old-growth forest and the appearance of secondary forest, ranged from 2 to 7 years. The median regeneration intervals of the interior, northeastern, and southern microregions were 3, 4, and 5 years, respectively. Even as the secular trend of deforestation continues in the Amazon biome and encroaches into the southern border of Amazonas state, the results herein indicate a possible resiliency toward secondary forest for undisturbed land on a timescale of several years, at least for mixed pasture-forest landscapes of kilometer-scale heterogeneity and assuming that a favorable climate persists for regeneration even as global change occurs.

Exploring the sustainable impacts of a clinical healthcare research scholarship programme

BACKGROUND

The NHS is the first public body globally to commit to net zero.

AIM

This study aimed to explore the environmental sustainability impact of a hospital scholarship programme.

METHOD

A sustainable quality improvement value framework was used to measure the programme's environmental, social and financial effects.

RESULTS

The social impact through face-to-face contact was most valued by scholars; there were also savings in carbon emissions and costs.

DISCUSSION

Training in sustainability is essential for the workforce but little infrastructure and expertise are available within organisations to support staff to provide sustainable healthcare in day-to-day practice.

CONCLUSION

Sustainable healthcare should be supported by education and national guidance and implementation plans should be drawn up to this end. The social impact of the framework used is often seen as less important than its environmental and financial components; however, as its value to scholars illustrates, the components are intertwined and should be considered of equal importance.

Anthropogenic land-use legacies underpin climate change-related risks to forest ecosystems

Forest ecosystems with long-lasting human imprints can emerge worldwide as outcomes of land-use cessation. However, the interaction of these anthropogenic legacies with climate change impacts on forests is not well understood. Here, we set out how anthropogenic land-use legacies that persist in forest properties, following alterations in forest distribution, structure, and composition, can interact with climate change stressors. We propose a risk-based framework to identify anthropogenic legacies of land uses in forest ecosystems and quantify the impact of their interaction with climate-related stress on forest responses. Considering anthropogenic land-use legacies alongside environmental drivers of forest ecosystem dynamics will improve our predictive capacity of climate-related risks to forests and our ability to promote ecosystem resilience to climate change.

Contribution of agricultural land conversion to global GHG emissions: A meta-analysis

Greenhouse gases (GHG) have extensive environmental effects by trapping heat and causing climate change and air pollution. Land plays a key role in the global cycles of GHG (i.e., carbon dioxide (CO₂), methane (CH₄), and nitrogen oxide (N₂O)), and land use change (LUC) can lead to the release of such gases into the atmosphere or the removal of them from the atmosphere. One of the most common forms of LUC is agricultural land conversion (ALC) where agricultural lands are converted for other uses. This study aimed to review 51 original papers from 1990 to 2020 that investigate the contribution of ALC to GHG emissions from a spatiotemporal perspective using a meta-analysis method. The results of spatiotemporal effects on GHG emissions showed that the effects were significant. The emissions were affected by different continent regions representing the spatial effects. The most significant spatial effect was relevant to African and Asian countries. In addition, the quadratic relationship between ALC and GHG emissions had the highest significant coefficients, showing an upward concave curve. Therefore, increasing ALC to more than 8 % of available land led to increasing GHG emissions during the economic development process. The implications of the current study are important for policymakers from two perspectives. First, to achieve sustainable economic development, policymaking should prevent the conversion of more than 90 % of agricultural land to other uses based on the turning point of the second model. Second, policies to control global GHG emissions should take into account spatial effects (e.g., continental Africa and Asia), which show the highest contribution to GHG emissions.

The carbon sink of secondary and degraded humid tropical forests

The globally important carbon sink of intact, old-growth tropical humid forests is declining because of climate change, deforestation and degradation from fire and logging^1-3. Recovering tropical secondary and degraded forests now cover about 10% of the tropical forest area⁴, but how much carbon they accumulate remains uncertain. Here we quantify the aboveground carbon (AGC) sink of recovering forests across three main continuous tropical humid regions: the Amazon, Borneo and Central Africa^5,6. On the basis of satellite data products^4,7, our analysis encompasses the heterogeneous spatial and temporal patterns of growth in degraded and secondary forests, influenced by key environmental and anthropogenic drivers. In the first 20 years of recovery, regrowth rates in Borneo were up to 45% and 58% higher than in Central Africa and the Amazon, respectively. This is due to variables such as temperature, water deficit and disturbance regimes. We find that regrowing degraded and secondary forests accumulated 107 Tg C year^-1 (90-130 Tg C year^-1) between 1984 and 2018, counterbalancing 26% (21-34%) of carbon emissions from humid tropical forest loss during the same period. Protecting old-growth forests is therefore a priority. Furthermore, we estimate that conserving recovering degraded and secondary forests can have a feasible future carbon sink potential of 53 Tg C year^-1 (44-62 Tg C year^-1) across the main tropical regions studied.

Linking land-use and land-cover transitions to their ecological impact in the Amazon

Human activities pose a major threat to tropical forest biodiversity and ecosystem services. Although the impacts of deforestation are well studied, multiple land-use and land-cover transitions (LULCTs) occur in tropical landscapes, and we do not know how LULCTs differ in their rates or impacts on key ecosystem components. Here, we quantified the impacts of 18 LULCTs on three ecosystem components (biodiversity, carbon, and soil), based on 18 variables collected from 310 sites in the Brazilian Amazon. Across all LULCTs, biodiversity was the most affected ecosystem component, followed by carbon stocks, but the magnitude of change differed widely among LULCTs and individual variables. Forest clearance for pasture was the most prevalent and high-impact transition, but we also identified other LULCTs with high impact but lower prevalence (e.g., forest to agriculture). Our study demonstrates the importance of considering multiple ecosystem components and LULCTs to understand the consequences of human activities in tropical landscapes.

Research on the Potential of Forestry’s Carbon-Neutral Contribution in China from 2021 to 2060

Forest ecosystems play a crucial role in mitigating climate change. To assess and quantify the specific emissions reduction benefits of forest carbon sequestration, this study used a combination of backpropagation neural networks, biomass conversion factor method, and logistic models to predict the carbon-neutral contribution from existing forests, planned afforestation, and forest tending activities in China from 2021 to 2060. The results showed that (1) the emissions reduction contribution of forestry pathways in China was 7.91% (8588.61 MtCO2) at the carbon peak stage and 8.71% (24,932.73 MtCO2) at the carbon-neutral stage; (2) the southwest was the main contributing region, while the east and north lagged; (3) afforestation activities made the largest emission reduction contribution during the forecast period, while the contribution of existing forests continued to decline; and (4) carbon sequestration contribution by different forest origins was comparable during the carbon peak, while the contribution of plantation forests was expected to surpass that of natural forests during the carbon-neutral period. In order to maximize the benefits of the carbon-neutral pathway of forestry, it is necessary to enhance the policy frameworks related to forestry activities, forestry financial investment systems, and sustainable forest management systems to maximize the potential of this sector. Furthermore, more focus should be placed on reduction sectors to ensure the timely achievement of carbon goals and boost sustainable development in the context of climate change.

Mapping native and non-native vegetation in the Brazilian Cerrado using freely available satellite products

Native vegetation across the Brazilian Cerrado is highly heterogeneous and biodiverse and provides important ecosystem services, including carbon and water balance regulation, however, land-use changes have been extensive. Conservation and restoration of native vegetation is essential and could be facilitated by detailed landcover maps. Here, across a large case study region in Goiás State, Brazil (1.1 Mha), we produced physiognomy level maps of native vegetation (n = 8) and other landcover types (n = 5). Seven different classification schemes using different combinations of input satellite imagery were used, with a Random Forest classifier and 2-stage approach implemented within Google Earth Engine. Overall classification accuracies ranged from 88.6-92.6% for native and non-native vegetation at the formation level (stage-1), and 70.7-77.9% for native vegetation at the physiognomy level (stage-2), across the seven different classifications schemes. The differences in classification accuracy resulting from varying the input imagery combination and quality control procedures used were small. However, a combination of seasonal Sentinel-1 (C-band synthetic aperture radar) and Sentinel-2 (surface reflectance) imagery resulted in the most accurate classification at a spatial resolution of 20 m. Classification accuracies when using Landsat-8 imagery were marginally lower, but still reasonable. Quality control procedures that account for vegetation burning when selecting vegetation reference data may also improve classification accuracy for some native vegetation types. Detailed landcover maps, produced using freely available satellite imagery and upscalable techniques, will be important tools for understanding vegetation functioning at the landscape scale and for implementing restoration projects.

Ephemeral forest regeneration limits carbon sequestration potential in the Brazilian Atlantic Forest

Although deforestation remains widespread in the tropics, many places are now experiencing significant forest recovery (i.e., forest transition), offering an optimistic outlook for natural ecosystem recovery and carbon sequestration. Naturally regenerated forests, however, may not persist, so a more nuanced understanding of the drivers of forest change in the tropics is critical to ensure the success of reforestation efforts and carbon sequestration targets. Here we use 35 years of detailed land cover data to investigate forest trajectories in 3014 municipalities in the Brazilian Atlantic Forest (AF), a biodiversity and conservation hotspot. Although deforestation was evident in some regions, deforestation reversals, the typical forest transition trajectory, were the prevalent trend in the AF, accounting for 38% of municipalities. However, simultaneous reforestation reversals in the region (13% of municipalities) suggest that these short-term increases in native forest cover do not necessarily translate into persistent trends. In the absence of reversals in reforestation, forests in the region could have sequestered 1.75 Pg C, over three times the actual estimated carbon sequestration (0.52 Pg C). We also showed that failure to distinguish native and planted forests would have masked native forest cover loss in the region and overestimated reforestation by 3.2 Mha and carbon sequestration from natural forest regeneration by 0.37 Pg C. Deforestation reversals were prevalent in urbanized municipalities with limited forest cover and high agricultural productivity, highlighting the importance of favorable socioeconomic conditions in promoting reforestation. Successful forest restoration efforts will require development and enforcement of environmental policies that promote forest regeneration and ensure the permanence of regrowing forests. This is crucial not only for the fate and conservation of the AF, but also for other tropical nations to achieve their restoration and carbon sequestration commitments.

Upscaling tropical restoration to deliver environmental benefits and socially equitable outcomes

The UN Decade on Ecosystem Restoration offers immense potential to return hundreds of millions of hectares of degraded tropical landscapes to functioning ecosystems. Well-designed restoration can tackle multiple Sustainable Development Goals, driving synergistic benefits for biodiversity, ecosystem services, agricultural and timber production, and local livelihoods at large spatial scales. To deliver on this potential, restoration efforts must recognise and reduce trade-offs among objectives, and minimize competition with food production and conservation of native ecosystems. Restoration initiatives also need to confront core environmental challenges of climate change and inappropriate planting in savanna biomes, be robustly funded over the long term, and address issues of poor governance, inadequate land tenure, and socio-cultural disparities in benefits and costs. Tackling these issues using the landscape approach is vital to realising the potential for restoration to break the cycle of land degradation and poverty, and deliver on its core environmental and social promises.

Large carbon sink potential of secondary forests in the Brazilian Amazon to mitigate climate change

Tropical secondary forests sequester carbon up to 20 times faster than old-growth forests. This rate does not capture spatial regrowth patterns due to environmental and disturbance drivers. Here we quantify the influence of such drivers on the rate and spatial patterns of regrowth in the Brazilian Amazon using satellite data. Carbon sequestration rates of young secondary forests (<20 years) in the west are ~60% higher (3.0 ± 1.0 Mg C ha^-1 yr^-1) compared to those in the east (1.3 ± 0.3 Mg C ha^-1 yr^-1). Disturbances reduce regrowth rates by 8-55%. The 2017 secondary forest carbon stock, of 294 Tg C, could be 8% higher by avoiding fires and repeated deforestation. Maintaining the 2017 secondary forest area has the potential to accumulate ~19.0 Tg C yr^-1 until 2030, contributing ~5.5% to Brazil's 2030 net emissions reduction target. Implementing legal mechanisms to protect and expand secondary forests whilst supporting old-growth conservation is, therefore, key to realising their potential as a nature-based climate solution.

Fire Occurrences and Greenhouse Gas Emissions from Deforestation in the Brazilian Amazon

This work presents the dynamics of fire occurrences, greenhouse gas (GHG) emissions, forest clearing, and degradation in the Brazilian Amazon during the period 2006–2019, which includes the approval of the new Brazilian Forest Code in 2012. The study was carried out in the Brazilian Amazon, Pará State, and the municipality of Novo Progresso (Pará State). The analysis was based on deforestation and fire hotspot datasets issued by the Brazilian Institute for Space Research (INPE), which is produced based on optical and thermal sensors onboard different satellites. Deforestation data was also used to assess GHG emissions from the slash-and-burn practices. The work showed a good correlation between the occurrence of fires in the newly deforested area in the municipality of Novo Progresso and the slash-and-burn practices. The same trend was observed in the Pará State, suggesting a common practice along the deforestation arch. The study indicated positive coefficients of determination of 0.72 and 0.66 between deforestation and fire occurrences for the municipality of Novo Progresso and Pará State, respectively. The increased number of fire occurrences in the primary forest suggests possible ecosystem degradation. Deforestation reported for 2019 surpassed 10,000 km2, which is 48% higher than the previous ten years, with an average of 6760 km2. The steady increase of deforestation in the Brazilian Amazon after 2012 has been a worldwide concern because of the forest loss itself as well as the massive GHG emitted in the Brazilian Amazon. We estimated 295 million tons of net CO2, which is equivalent to 16.4% of the combined emissions of CO2 and CH4 emitted by Brazil in 2019. The correlation of deforestation and fire occurrences reported from satellite images confirmed the slash-and-burn practice and the secondary effect of deforestation, i.e., degradation of primary forest surrounding the deforested areas. Hotspots’ location was deemed to be an important tool to verify forest degradation. The incidence of hotspots in forest area is from 5% to 20% of newly slashed-and-burned areas, which confirms the strong impact of deforestation on ecosystem degradation due to fire occurrences over the Brazilian Amazon.