Potential Afforestation Research Articles

Estimation of Spatial–Temporal Dynamic Evolution of Potential Afforestation Land and Its Carbon Sequestration Capacity in China

Estimation of Spatial–Temporal Dynamic Evolution of Potential Afforestation Land and Its Carbon Sequestration Capacity in China

Optimizing land use for climate mitigation using nature based solution (NBS) strategy: a study on afforestation potential and carbon sequestration in Rajasthan, India

Rajasthan faces significant environmental challenges, including the pressing need for effective climate change mitigation strategies. Recognizing afforestation as a vital tool in this endeavor, this study leverages the latest in remote sensing and geospatial analysis to map out the state's afforestation potential. The goal is to assess land suitability across Rajasthan for afforestation projects and evaluate the potential carbon sequestration capabilities of different tree species. This aims to inform sustainable land management strategies that can contribute to climate change mitigation. By integrating satellite imagery, land cover data, terrain analysis, and vegetation indices, the study evaluates environmental factors such as slope, soil moisture, and vegetation health to identify areas optimal for tree planting. A carbon sequestration model was also developed to estimate sequestration rates based on species-specific growth patterns. Findings indicate that approximately 40% of Rajasthan is suitable for afforestation, with potential carbon sequestration rates ranging from 2 to 8 tons per hectare per year. Species such as Azadirachta indica (Neem) and Prosopis cineraria (Khejri) are identified as particularly effective for short-term sequestration, while Phyllanthus emblica (Amla) and Ziziphus mauritiana (Ber) are better suited for long-term carbon capture. This research highlights the importance of targeted afforestation using suitable tree species as a nature-based solution (NBS) for climate change mitigation in Rajasthan. The study offers a data-driven approach to enhancing ecosystem resilience and supports decision-making for climate adaptation in arid regions, highlighting the significant potential of Rajasthan's land for carbon sequestration through afforestation.

Broadleaf afforestation impacts on terrestrial hydrology insignificant compared to climate change in Great Britain

Abstract. Widespread afforestation has been proposed internationally to reduce atmospheric carbon dioxide; however, the specific hydrological consequences and benefits of such large-scale afforestation (e.g. natural flood management) are poorly understood. We use a high-resolution land surface model, the Joint UK Land Environment Simulator (JULES), with realistic potential afforestation scenarios to quantify possible hydrological change across Great Britain in both present and projected climate. We assess whether proposed afforestation produces significantly different regional responses across regions; whether hydrological fluxes, stores and events are significantly altered by afforestation relative to climate; and how future hydrological processes may be altered up to 2050. Additionally, this enables determination of the relative sensitivity of land surface process representation in JULES compared to climate changes. For these three aims we run simulations using (i) past climate with proposed land cover changes and known floods and drought events; (ii) past climate with independent changes in precipitation, temperature, and CO2; and (iii) a potential future climate (2020–2050). We find the proposed scale of afforestation is unlikely to significantly alter regional hydrology; however, it can noticeably decrease low flows whilst not reducing high flows. The afforestation levels minimally impact hydrological processes compared to changes in precipitation, temperature, and CO2. Warming average temperatures (+3 °C) decreases streamflow, while rising precipitation (130 %) and CO2 (600 ppm) increase streamflow. Changes in high flow are generated because of evaporative parameterizations, whereas low flows are controlled by runoff model parameterizations. In this study, land surface parameters within a land surface model do not substantially alter hydrological processes when compared to climate.

Optimizing China’s Afforestation Strategy: Biophysical Impacts of Afforestation with Five Locally Adapted Forest Types

Recent research has mapped potential afforestation land to support China’s goal of achieving “carbon neutrality” and has proposed tree species selection to maximize carbon uptake. However, it overlooked biophysical climatic effects, which have a more significant impact on local temperature than CO2 reduction. This study aims to present a comprehensive understanding of how afforestation in China affects local and regional climates through biophysical processes. It focuses on the latitudinal patterns of land surface temperature differences (ΔLST) between five locally adapted forest types and adjacent grasslands using satellite-based observations. Our key findings are as follows: Firstly, broadleaf forests and mixed forests exhibit a stronger cooling effect than coniferous forests due to differences in canopy structure and distribution. Specifically, the net cooling effects of evergreen broadleaf forests (EBFs), deciduous broadleaf forests (DBFs), and mixed forests (MFs) compared to grasslands are −0.50 ± 0.10 °C (mean ± 95% confidence interval), −0.33 ± 0.05 °C, and −0.36 ± 0.06 °C, respectively, while evergreen needleleaf forests (ENFs) compared to grasslands are −0.22 ± 0.11 °C. Deciduous needleleaf forests (DNFs) exhibit warming effects, with a value of 0.69 ± 0.24 °C. In regions suitable for diverse forest types planting, the selection of broadleaf and mixed forests is advisable due to their enhanced local cooling impact. Secondly, temperate forests have a net cooling effect to the south of 43° N, but they have a net warming effect to the north of 48° N compared to grasslands. We recommend caution when planting DNFs, DBFs, and MFs in northeastern China, due to the potential for local warming. Thirdly, in the mountainous areas of southwestern China, especially when planting ENFs and MFs, tree planting may lead to local warming. Overall, our study provides valuable supplementary insights to China’s existing afforestation roadmap, offering policy support for the country’s climate adaptation and mitigation efforts.

Source or decomposition of soil organic matter: what is more important with increasing forest age in a subalpine setting?

Afforestation has been the dominant land-use change in the Swiss Alps during the last decades which has not only the potential to increase soil organic carbon sequestration, but it has also the potential to alter soil organic matter (SOM) dynamics through the vegetation shift and change in organic matter (OM) input into soils. The effects of afforestation on SOM dynamics, however, are still not fully understood as specific sources of OM and modifications of soil processes influencing decomposition and preservation remain largely unknown on alpine to subalpine slopes. Within this study we aimed to identify the potential sources and the decomposition of OM in a subalpine afforestation chrono-sequence (0–130 years) with Norway spruce (Picea abies L.) on a former pasture by using a multi-proxy molecular marker approach. We observed that leaf-derived OM plays an essential role in the pasture areas, while root-derived OM only plays a minor role in pasture and forest areas. Needle-derived OM represents the dominant source of SOM with increasing forest age, while understory shrubs and moss also contribute to the OM input in younger forest stand ages. However, needle litter and buildup of organic layers and subsequently less input of fresh OM from organic horizons to mineral soil can result in increased OM decomposition in mineral soils rather than contributing to additional SOM stabilization in mineral soils. This was most pronounced in the oldest forest stand (130-year-old) in the investigated afforestation sequence, particularly in deeper soil horizons (10–45 cm). Thereby, our study provides new insights into SOM dynamics following afforestation, especially with respect to the long-term SOM sequestration potential of afforestation of subalpine pasture soils.

Afforestation triggers water mining and a single pulse of water for carbon trade-off in deep soil

Clarifying the water-root-carbon nexus in the entire root zone is crucial for unlocking the potential of afforestation in mitigating climate change. But the nexus in deep soil (depth > 1 m) remains poorly understood. Here we report contrasts in deep soil water and root distributions across 72 paired sites of adjacent farmlands, representing typical pre-afforestation conditions, and tree plantations, representing modern afforestation across the Loess Plateau of China. Ranging from 6 to 25 m of depth, these profiles included plantations of 13 tree species ranging from 1 to 25 years of age. The observations revealed sustained water mining in deep soil following afforestation with mean soil water decline of 75.2 ± 9.8 mm yr−1 that were accompanied by root deepening rates of 1.00 ± 0.06 m yr−1 with an associated biomass input of 0.18 ± 0.04 Mg C ha−1 yr−1. A water for carbon trade-off in deep soil become evident, likely involving a single pulse of C gains and water losses as no signs of soil rewetting under tree plantations where observed total soil water exhaustion that accumulated the equivalent of up to 2.8 years of mean annual precipitation inputs. The reported water-root-carbon nexus reveals overlooked hydrological costs and, more importantly, over-optimistic expectations of sustained C sequestration under afforestation that may rather represent a single-pulsed C gain supported by deep soil water exhaustion.

Agricultural development has not necessarily caused forest cover decline in semi-arid northern China over the past 12,000 years

Forest cover significantly affects the global carbon cycle, biodiversity, and human welfare, but is seriously threatened by human activities. Here we found that anthropogenic forces did not necessarily lead to forest cover decline in the marginal agricultural region of northern China based on a quantitative reconstruction of 12,000-years forest cover changes using modern analog technique and random forest. The forest cover was strongly affected by human activities in the core agricultural region, as indicated by the high independent effects of archeological sites (38.3%) and burning area (42.3%). In contrast, climate impacted the forest cover in the marginal agricultural region, where the annual precipitation and summer mean temperature contributed 52.4% and 27.4%, respectively. Agricultural development in the marginal agricultural region likely occurred in the river valley or sunny slopes, not overlapping with zonal forests growing on shady slopes. This study implies much less afforestation potential than previously expected in the marginal agricultural region.

Carbon sequestration and emission mitigation potential of afforestation and reforestation of unproductive territories

Carbon sequestration and emission mitigation potential of afforestation and reforestation of unproductive territories

The Carbon Sink Potential of Southern China After Two Decades of Afforestation.

Afforestation and land use changes that sequester carbon from the atmosphere in the form of woody biomass have turned southern China into one of the largest carbon sinks globally, which contributes to mitigating climate change. However, forest growth saturation and available land that can be forested limit the longevity of this carbon sink, and while a plethora of studies have quantified vegetation changes over the last decades, the remaining carbon sink potential of this area is currently unknown. Here, we train a model with multiple predictors characterizing the heterogeneous landscapes of southern China and predict the biomass carbon carrying capacity of the region for 2002-2017. We compare observed and predicted biomass carbon density and find that during about two decades of afforestation, 2.34 PgC have been sequestered between 2002 and 2017, and a total of 5.32 Pg carbon can potentially still be sequestrated. This means that the region has reached 73% of its aboveground biomass carbon carrying capacity in 2017, which is 12% more than in 2002, equal to a decrease of 0.77% per year. We identify potential afforestation areas that can still sequester 2.39 PgC, while old and new forests have reached 87% of their potential with 1.85 PgC remaining. Our work locates areas where vegetation has not yet reached its full potential but also shows that afforestation is not a long-term solution for climate change mitigation.

Identifying prioritized afforestation types in ecologically vulnerable zones of Northern China considering reducing water consumption and increasing carbon sequestration

Afforestation is one of the most important measures to control soil erosion and desertification in Northern China. Meanwhile, considering that afforestation in Northern China needs to increase carbon sequestration (CS) and reduce water consumption (WC), it is essential to select prioritized afforestation types in suitable regions. In this work, we identified ecologically vulnerable zones based on soil water and wind erosion assessment, evaluated tree and shrub afforestation suitability, and thus recognized potential afforestation regions. Further, we set four scenarios for different goals, and identified the prioritized afforestation types in each scenario. The results showed that potential afforestation regions are mainly distributed in the Loess Plateau, Western Liao River, Ordos Plateau, and Tarim Basin. Scenario 1 (aiming to minimize WC) is dominated by shrub afforestation and grassland restoration. This scenario will reduce WC by 3.1%-6.4% compared to other scenarios, but it will also decrease CS by 9.4%-56.1% and soil conservation (SC) by 7.7%-13.0%. Scenario 2 (aiming to maximize CS) is dominated by tree and shrub afforestation. This scenario will fix 41.8%-56.1% more carbon, and consume 3.0%-6.4% more water than the other scenarios. Meanwhile, this scenario can maximize SC, but also may reduce sand fixation (SF). Scenario 3 (aiming to maximize CS in humid region and minimize WC in arid region) and Scenario 4 (aiming to enhance both SC and SF) are dominated by shrub afforestation, tree afforestation and grassland restoration. The two scenarios can balance CS and WC, and have advantages in improving both SC and SF. In addition, Scenario 4 performs better than Scenario 3. In the future, it is better to implement tree afforestation mainly in sub-humid area, and conduct shrub afforestation mainly in arid and semi-arid regions. This study can provide guidance for the planning and management of afforestation projects in Northern China and other water scarcity areas.

The potential for carbon sequestration by afforestation can be limited in dryland river basins under the pressure of high human activity

Dryland regions cover >40 % of the Earth's land surface. Both human activities and climate change have driven forest expansion in parts of dryland regions. Afforestation has been implemented widely to enhance carbon sequestration and benefit the ecological environment of many global drylands. However, the potential and available afforestation space in drylands is uncertain due to the conflicts between additional forest areas and available water. How afforestation will affect the potential for forest carbon stock is also unclear. This paper assessed the future spatial distribution of afforestation and potential forest carbon stock in a typical dryland region, the Yellow River Basin (YRB), which has experienced rapid afforestation and high human activity pressure over the past several decades. Combining the future land use change model (FLUS) and local important development planning, we simulated future afforestation distributions and estimated potential forest carbon stock under the ecological restoration, urban expansion, and cultivated land protection scenarios. The afforestation carbon stock was predicted by considering the dynamic change trends of the mature forest, the immature forest, and new afforestation. The results demonstrated that the potential afforestation area would be limited to 4000 km2 in the YRB accounting for less than one-twentieth of the total forest area. Accordingly, the maximum potential forest carbon stock would increase only 59.5 × 106 t. These findings implies that afforestation programs in drylands should further consider the optimum allocation of afforestation space and the balance between carbon and water in drylands, especially under a changing climate with increasing human activities.

Deforestation intensifies daily temperature variability in the northern extratropics

While the biogeophysical effects of deforestation on average and extreme temperatures are broadly documented, how deforestation influences temperature variability remains largely unknown. To fill this knowledge gap, we investigate the biogeophysical effects of idealized deforestation on daily temperature variability at the global scale based on multiple earth system models and in situ observations. Here, we show that deforestation can intensify daily temperature variability (by up to 20%) in the northern extratropics, particularly in winter, leading to more frequent rapid extreme warming and cooling events. The higher temperature variability can be attributed to the enhanced near-surface horizontal temperature advection and simultaneously is partly offset by the lower variability in surface sensible heat flux. We also show responses of daily temperature variability to historical deforestation and future potential afforestation. This study reveals the overlooked effects of deforestation or afforestation on temperature variability and has implications for large-scale afforestation in northern extratropic countries.

What can the Glasgow Declaration on Forests bring to global emission reduction?

What can the Glasgow Declaration on Forests bring to global emission reduction?

Conservation genetics of Firmiana major, a threatened tree species with potential for afforestation of hot, arid climates

Firmiana major (Malvaceae) is a dominant tree species in hot, arid valleys with savanna vegetation in southwest China. Due to severe human disturbance, the populations of F. major declined sharply and was once considered extinct in the wild. Until 2020, eight populations of F. major were found by our investigation and it was listed as a Plant Species of Extremely Small Populations (PSESP) in Yunnan Province, China, for urgent rescuing during the next decade. To guide its conservation, the genetic structure, demographic history, and distribution model were studied. Four genetic groups of F. major were revealed and their divergence times coincided with warming periods during the last glacial stage. The distribution model showed a narrow habitat for F. major around the hot, arid areas of Yuanmou Basin, Jingsha arid-hot valleys and their adjacent areas, which enhanced its endangered situation. Based on the study, several conservation suggestions for F. major were proposed including adopting its germplasms with better drought tolerance for afforestation in this area. • Firmiana major is an endangered yet dominant tree that has potential to be a native greening species in savanna vegetation. • We found four genetic groups of F. major and one group showed climatic differentiation from other groups. • Divergence time of F. major was related to the warm periods in the last glacial stage. • The study predicted a relatively narrow distribution of F. major in hot, arid areas which enhanced its endangered situation. • We provided population recovery goals and conservation strategies for F. major based on the results.

Biophysical Effects of Afforestation on Land Surface Temperature in Guangdong Province, Southern China

AbstractDeveloping effective climate mitigation strategies under global warming requires a comprehensive understanding of the biophysical mechanism of how afforestation affects the climate and environment. The planted forests in southern China are an essential carbon sink. However, the impacts of radiative and non‐radiative processes on land surface temperature caused by converting open land (i.e., grassland and cropland) and natural forests to planted forests remain unclear. We used satellite observations and intrinsic biophysical mechanism theory‐based energy balance models to estimate the biophysical impacts of potential afforestation of open land and natural forests on surface temperature from 2000 to 2010 in Guangdong Province, southern China. Results showed that afforestation of open land had a consistent net cooling effect. Due to the afforestation of natural forests, the modeled results revealed that afforestation among all conversion types had a net warming effect of 0.15 ± 0.5 K, which caused by the change in energy redistribution factor although uncertainty remains. While the most significant warming caused by converting natural forest to planted forests was also slightly affected by albedo. The afforestation's non‐radiative and radiative processes led to a slight warming of 0.143 ± 0.43 K and a cooling of −0.096 ± 0.19 K, respectively. The non‐radiative process dominates the effect of afforestation on the surface temperature, with the overall non‐radiative forcing index greater than 73% ± 0.59%. Our study highlights the need of protecting natural forests and provides a practical method for assessing the impacts of afforestation on the local climate and the effectiveness of climate mitigation efforts.

Mangrove distribution and afforestation potential in the Red Sea

Mangrove ecosystems represent one of the most effective natural environments for fixing and storing carbon (C). Mangroves also offer significant co-benefits, serving as nurseries for marine species, providing nutrients and food to support marine ecosystems, and stabilizing coastlines from erosion and extreme events. Given these considerations, mangrove afforestation and associated C sequestration has gained considerable attention as a nature-based solution to climate adaptation (e.g., protect against more frequent storm surges) and mitigation (e.g. offsetting other C-producing activities). To advance our understanding and description of these important ecosystems, we leverage Landsat-8 and Sentinel-2 satellite data to provide a current assessment of mangrove extent within the Red Sea region and also explore the effect of spatial resolution on mapping accuracy. We establish that Sentinel-2 provides a more precise spatial record of extent and subsequently use these data together with a maximum entropy (MaxEnt) modeling approach to: i) map the distribution of Red Sea mangrove systems, and ii) identify potential areas for future afforestation. From these current and potential mangrove distribution maps, we then estimate the carbon sequestration rate for the Red Sea (as well as for each bordering country) using a meta-analysis of sequestration values surveyed from the available literature. For the mangrove classification, we obtained mapping accuracies of 98 %, with a total Red Sea mangrove extent estimated at approximately 175 km2. Based on the MaxEnt approach, which used soil physical and environmental variables to identify the key factors limiting mangrove growth and distribution, an area of nearly 410 km2 was identified for potential mangrove afforestation expansion. The factors constraining the potential distribution of mangroves were related to soil physical properties, likely reflecting the low sediment load and limited nutrient input of the Red Sea. The current rate of carbon sequestration was calculated as 1034.09 ± 180.53 Mg C yr−1, and the potential sequestration rate as 2424.49 ± 423.26 Mg C yr−1. While our results confirm the maintenance of a positive trend in mangrove growth over the last few decades, they also provide the upper bounds on above ground carbon sequestration potential for the Red Sea mangroves.

Identification of priority areas for afforestation in the Loess Plateau region of China

China has led global greening processes over recent decades, however, a series of negative impacts have inevitably emerged in some areas, especially on the Loess Plateau. While the potential for afforestation of the Loess Plateau has been identified, the micro-regions where afforestation should be prioritized have yet to be identified. We constructed a framework for identification of land suitable for forest on the Loess Plateau. By simulating land-use changes on the Loess Plateau under various development scenarios for the period from 2020 to 2030, we identified land that is suitable for afforestation and explored the trends and spatial distribution of different forest stands. The results show that only ∼ 40 km2 on the Loess Plateau is suitable for forest growth by 2030, mainly in the eastern region, with the southeastern part of the Loess Plateau at greater risk of degradation. The suitable land for forest growth is fragmented. Under the current climate conditions and policy background, we believe there is limited opportunity for large-scale conversion of farmland to forest on the Loess Plateau; however, if the afforestation areas are scientifically planned, it is feasible to achieve greening in local areas. Grasslands may be a more suitable primary approach to ecological restoration in the Loess Plateau region. The results will help guide more efficient and sustainable afforestation projects in the Loess Plateau region.

Ecological development of mangrove plantations in the Bangladesh Delta

Afforestation is a process used in recovering the global mangrove cover. Succession or development in mangrove communities during mangrove afforestation has rarely been described yet is important for understanding the potential of afforestation in creating diverse and functional mangroves. Since 1966, the Government of Bangladesh has created nearly 280 km2 of plantation mangroves (7.5% of the extent of the Sundarbans mangrove forest and 0.21% of the global mangroves extent) on the Delta of the Ganges, Brahmaputra and Meghna Rivers, located east of the Sundarbans mangroves. Here, we investigated the development of these plantation mangroves, assessing their community structure and species richness over a 40-year chronosequence in comparison to natural mangroves in the same region. Tree communities in the plantations reached a maximum mean aboveground biomass (AGB) of ∼157 ± 13 Mg dry weight ha−1, achieving equivalence in tree aboveground biomass and tree density (255 ± 2 individuals ha−1) to natural mangroves by 20 and 39 years respectively. Our dataset from plantations aged between 10 and 42 years indicated that structural complexity (Ic) was higher in older plantations than in younger plantations. We found that the tree community structure of older mangrove plantations was more diverse in the eastern region of the delta compared to the central and western regions, and the landward plantations were more diverse than the plantations fringing the oceans. One of the originally planted mangrove species, Sonneratia apetala, was dominant in these plantations. However, we recorded 8 mangrove tree species from 5 genera in the plantations, despite only two species (S. apetala and Avicennia officinalis) being planted. Our data indicated that while the tree structure of the established mangrove plantations was similar to natural mangroves within 42 years, equivalent species richness may not be reached for more than 40 years. Therefore, adoption of management to enhance natural successional or development processes in afforestation programs, for example by planting a diverse mix of species, could improve the effectiveness of afforestation in conserving biodiversity.

Characterization of Pinus densiflora var. zhangwuensis S.J.Zhang, C.X.Li & X.Y.Yuan complete chloroplast genome

Pinus densiflora var. zhangwuensis S.J.Zhang, C.X.Li & X.Y.Yuan, a tree species with promising afforestation potential in northern China. Here, we assembled and annotated the complete chloroplast (cp) genome of P. densiflora var. zhangwuensis using the Oxford Nanopore sequencing technology. The cp genome was 119,725 bp in length, exhibiting a typical quadripartite structure with a large single-copy (LSC: 65,552 bp) and a small single-copy (SSC: 53,183 bp) separated by a pair of inverted repeats regions (IRA and IRB: each of 495 bp) region. The overall GC content is 37.3%. The genome was predicted to encode 112 distinct genes, including 72 protein-coding, 36 tRNA, and four rRNA genes. Maximum-likelihood (ML) phylogenetic for cp genome sequences of 18 Pinaceae species revealed that P. densiflora var. zhangwuensis was closely related to Pinus sylvestris.

Spatial assessment of land degradation using MEDALUS focusing on potential afforestation and reforestation areas in Ethiopia

AbstractEthiopia currently faces severe land degradation and desertification and has attracted increasing attention for international restoration projects. However, selecting appropriate potential afforestation and reforestation areas is challenging because of limited geospatial assessment tools on a national scale. Therefore, the globally used MEDALUS approach was applied to identify areas sensitive to land degradation and desertification, and indices were utilized to establish the main drivers from 2000 to 2019. The value of the environmentally sensitive area index (ESAI) ranged from 1 to 1.58. Addis Ababa, Afar, Somali, and Tigray had relatively high ESAI values, approaching the over 1.42 which regarded critical thresholds. However, the main driver of land degradation and desertification was identified as the management quality index (MQI) and the analysis of relationships indicated that the climate quality index, soil quality index, and MQI caused changes in the vegetation quality index. Increasing housing, agricultural transitions, and urbanization, were identified by on‐site visual interpretation. Even though some land cover changes and fluctuations of the indices existed on a national scale, the deforestation areas in Amhara, Benshangul‐Gumaz, and Oromia West have the highest priority for forest restoration projects. Thus, international attention to afforestation and reforestation clean development mechanism (A/R CDM) and reducing emission from deforestation and forest degradation (REDD+) is required to combat desertification and to secure land degradation neutrality in Ethiopia.