Tree Planting Research Articles

Enhancing highland ecosystems in East Hararge, Ethiopia: evaluating intervention strategies for species diversity, soil organic carbon stock, and carbon sequestration

Forest loss and soil degradation pose significant challenges globally, particularly in developing nations like Ethiopia. Various intervention strategies have been implemented to rehabilitate degraded ecosystems. However, research gaps exist in understanding the most effective approaches, particularly in highland ecosystems. This study aimed to evaluate the effectiveness of different intervention strategies on species diversity and carbon stock in the West Hararghe zone, specifically at the Doba district Hades site. The data was collected from 5 February 2022 to 10 December 2022. The study area was characterized by systematic plots and transects to assess vegetation diversity and soil properties across four intervention categories: (physical; only soil and water conservation structures were used, enclosure; only animal and human interaction was restricted, biological; only different tree species were planted, biophysical; both soil water conservation and tree planting were used). Soil samples were collected at different depths, and biomass estimation was conducted using established formulas. Statistical analyses, including one-way ANOVA and post-hoc tests, were performed to test the level of significance. Biophysical interventions exhibited the highest species diversity index (SDI) (4.65 ± 1.21), followed by enclosure interventions (1.68 ± 0.58), while physical interventions recorded the lowest SDI (0.63 ± 0.18). Enclosure interventions led to the highest soil organic carbon (SOC) stocks at 40.13 t C ha−1, followed by biophysical interventions at 39.26 t C ha−1. Physical interventions resulted in the lowest SOC stocks at 23.9 t C ha−1, underscoring their potential for carbon sequestration. Biophysical interventions, which include both above-ground and below-ground biomass, showed significant carbon stock accumulation, totaling 173.8 t C ha−1 (39.26 t C ha−1 from SOC and 114.6 t C ha−1 from biomass), highlighting their effectiveness in enhancing ecosystem resilience. Other studies support these findings, underscoring the importance of context-specific approaches and long-term monitoring for sustainable land management. Enclosure and biophysical interventions emerge as promising strategies for enhancing species diversity and soil health, as well as promoting carbon sequestration in highland ecosystems. These findings emphasize the need for informed decision-making and community involvement in ecosystem restoration efforts to achieve meaningful and lasting impacts.

Integration of very high-resolution stereo satellite images and airborne or satellite Lidar for Eucalyptus canopy height estimation

Eucalyptus plantations cover extensive areas in tropical regions and require accurate growth monitoring for efficient management. Traditional in-situ measurements, while necessary, are labor-intensive and impractical for large-scale assessments. Very high-resolution satellite stereo imagery is playing an increasingly important role in the estimation of fine Digital Surface Models (DSMs) across landscapes. However, its ability to estimate canopy height models (CHMs) has not been widely investigated. This study investigates the integration of high-resolution satellite stereo imagery from the Pleiades sensor with airborne or satellite Lidar data to estimate canopy height over eucalyptus plantations. Two study sites were selected in Brazil, representing flat and semi-mountainous topographies, Mato Grosso do Sul (MS) and Sao Paulo (SP), respectively. Digital Surface Models generated from Pleiades images (DSMP) were combined with Digital Terrain Models extracted from airborne Lidar data (DTMALS) to create Canopy Height Models (CHMALS). The evaluation of the CHMALS was based on two in situ canopy height measurements (Hmax and Hmean). For the SP site, the CHMALSmax, which is the average height of top 10% pixel values within each plot, correlated well with in situ Hmean, which is the average height of 10 central trees (r = 0.98), showing a bias of 1.4 m, RMSE of 3.1 m, and rRMSE of 18.5%. At the MS site, CHMALSmax demonstrated a bias of 1.9 m, RMSE of 2.3 m, rRMSE of 17.3%, and r correlation of 0.92. Despite a tendency to underestimate heights below 20 m in young tree plantations with open canopy, the results indicate reliable canopy height estimation. The study also investigates the potential of Global Ecosystem Dynamics Investigation (GEDI) elevation data as an alternative to DTMALS in absence of airborne Lidar data. The resulting CHMGedi is promising but slightly less accurate than Lidar-based CHMs. The best GEDI-based CHM (CHMGedimax) showed a bias and rRMSE of 1.3 m and 20.5% for the SP site, and 2.2 m and 24.9% for the MS site. These findings highlight the potential for integrating Pleiades and Lidar data for efficient and accurate canopy height monitoring in eucalyptus plantations.

Regeneration and Genetic Transformation in Eucalyptus Species, Current Research and Future Perspectives

Eucalyptus is an important plantation tree with a high economic value in China. The tree contributes significantly to China’s timber production. The stable and efficient Eucalyptus regeneration system and genetic transformation system are of great significance for exploring the regulatory function and possible genetic breeding capacity of important genes in the species. However, as a woody plant, Eucalyptus has problems, such as a long generation cycle, strong specificity of the regeneration system, and a low genetic conversion rate, which seriously limit the rapid development of Eucalyptus genetics and breeding programs. The present review summarizes the status of research on Eucalyptus regeneration and genetic transformation, with a focus on the effects of explants, media, plant growth regulators (PGRs), and concentrations in the Eucalyptus regeneration process. In addition, the effects of genotype, Agrobacterium, antibiotics, preculture, and co-culture on the genetic transformation efficiency of Eucalyptus are discussed. Furthermore, the study also summarizes the problems encountered in Eucalyptus regeneration and genetic transformation, with reference to previous studies, and it outlines future developments and prospects. The aim was to provide a reference for solving the problems of genetic instability and the low transformation efficiency of eucalyptus, and to establish an efficient and stable eucalyptus regeneration and transformation system to accelerate the process of its genetic improvement.

Retraction of “Convolutional neural network for UAV image processing and navigation in tree plantations based on deep learning”

Retraction of “Convolutional neural network for UAV image processing and navigation in tree plantations based on deep learning”

Trends in planted native tree biomass established in a tropical Andes city water basins

Studying tree growth processes helps us evaluate the success of restoration efforts in recovering ecosystem processes such as carbon accumulation. Here, we study aboveground biomass dynamics in four common‐endemic tree species from the tropical Andes (Quercus humboldtii, Retrophyllum rospigliosii, Citharexylum subflavescens, and Croton magdalenensis), established in the main water supply basins of Medellín, Colombia. We use measurements from 19 permanent plots from five censuses between 2010 and 2023 to develop biomass equations as a function of t for each species (B = f[t]) by combining tree growth models of diameter (D) as a function of time (t) and pre‐existing allometric equations of biomass (B) developed in the same site as a function of D and wood density (ρ). We found that, because of initially higher growth rates characteristic of species belonging to the fast‐growing end of the fast‐slow growth economic spectrum, C. magdalenensis and C. subflavescens were the species with higher biomass accumulation at 13 years (142 and 132 kg, respectively). However, the potential of the slow‐growing species (Q. humboldtii and R. rospigliosii) for carbon sequestration initiatives in the long term was highlighted. To our knowledge, this is the first study in the region examining the dynamics of aboveground biomass in Andean restoration programs. It combines growth models and allometric equations, which can be useful for measuring the success of the implementation of ecological restoration programs and evaluating the need to apply adaptive management strategies.

Forest assisted migration and adaptation plantings in the Northeastern US: perspectives and applications from early adopters

Threats to the future function of forested ecosystems and stability of ecosystem service provisioning due to global change have motivated climate-adaptive forest management strategies that include various forms of tree planting termed “adaptation plantings”. Despite the emergence of these strategies, less is known as to how foresters and other natural resource managers perceive or are engaged with adaptation plantings like forest assisted migration (FAM). This knowledge gap is most pronounced in regions like New England and the North Central US (hereafter, the Northeastern US) where tree planting is less common but expected to be an important forest management tool for adaptation. To address this, we surveyed 33 natural resource managers in this region actively engaged in climate change adaptation (i.e., early adopters of the practice) to assess how tree planting for adaptation is currently being pursued against the perceived barriers, opportunities, and potential future engagement with the strategy. Survey respondents overwhelmingly (93.5%) forecast increases in the future use of adaptation plantings in their work in the region, attributed to increased awareness, acceptance, and interest in the practice. Respondents expressed notable interest in strategies related to diversification and most types of FAM (e.g., assisted population expansion and assisted range expansion), but hesitancy to engage with more contentious planting types like afforestation or FAM linked to the long-distance translocation of exotic species (e.g., assisted species migration). Although examples of local enrichment plantings (i.e., non-FAM) proliferate, nineteen of the top twenty most common tree genera planted contain at least one example of FAM in the study region. The most notable barriers reported were themed as 1) biotic and abiotic, 2) information and material, and 3) policy, social, and economic factors. While most respondents report difficulty obtaining adequate planting material from nurseries (i.e., seedlings), over 80% placed orders shortly before planting (< 1 year) which likely generates difficulty in sourcing seedlings suited for a specific site and future range of environmental conditions. Although this study is limited by focusing on subset of natural resource managers who are early adopters of climate change adaptation within the region, valuable inferences into the barriers and trends are possible from this population serving on the front lines of forest adaptation. Together, these results from early adopters suggest a potentially growing need for allocating resources that engage forest stewards in adaptation planning and serve to refine policy, financing, and management practices to support this adaptation strategy in this region and beyond.

Ecological assessment and diversity of woody plants in plantations of frankincense trees (Boswellia papyrifera (Del.) Hochst.) in AlGerri Forest, Blue Nile State, Sudan

هدفت هذه الدراسة إلى تقييم تنوع أنواع الشجيرات والأشجار داخل مزارع اشجار اللبان (Boswellia papyrifera (Del.) Hochst.) في منطقة القري بولاية النيل الأزرق. 18 نمازج دائرية منتظمة حددت لاخذ و تسجيل البيانات تبلغ مساحتة الواحد منها 0.1 هكتار. (نصف القطر = 17.84) مع مسافات تباعد تبلغ 100 متر بين كل نموزج و الاخر، تم استخدامها لجمع البيانات. تم تحديد ما مجموعه 13 نوعًا خشبيًا تنتمي إلى 7 عائلات في مجموعتين من مزارع اشجار اللبان. ساد نوع اشجار اللبان (Boswellia papyrifera) على الأنواع الخشبية في جميع مجتمعات الغطاء النباتي، وتليها انواع الهبيل (Combretum hartmannianum) و الطلح (Acacia seya). كان مؤشرا التنوع في شانون (H) للمجتمع (1) والمجتمع (2) 0.328 و 0.429 على التوالي. كانت قيم مؤشر Pielous Evenness (E) في المجتمع (1) المجتمع (2) 0.344 و 0.429 على التوالي. كثافة المجتمع (1) والمجتمع (2) 609.1 و 309.08 نبات / هكتار. على التوالى. أظهر توزيع الأنواع الخشبية أن 61.54٪ من الأنواع تتواجد في تجمعات في توزيعها و 38.46٪ من الأنواع موزعة عشوائياً. تم استخدام التحليل العنقودي المستند إلى الرابط الفردي Bray-Curtis لتقييم التشابه بين تكوين الأنواع الخشبية عبر 18 نموزج عينة.

Effects of aerial liming on soil chemical and biological properties in metal contaminated and inaccessible lands in Ontario (Canada).

The manual addition of lime to soil, in addition to tree planting and fertilization have been the dominant strategy described in restoration protocols for ecosystems damaged by acid rain and metal contamination. Investigations on aerial-limed soils in inaccessible lands are limited. The objective of this study was to assess the effects of aerial liming on soil pH, organic matter, microbial biomass, and enzymatic activities, and aboveground plant population quality in metal-contaminated lands in northern Ontario, Canada. Soil samples were collected from three sites around the City of Greater Sudbury with each pair being composed of a reclaimed (areal-limed) site and an adjacent undisturbed (unlimed) area. Soil physico-chemistry, microbial biomass (assessed by Phospholipid fatty acid analysis) and enzymatic activities were analyzed. Soil pH was higher in limed sites compared to unlimed at recently restored sites (Baby Lake and Wahnapitae) but not at the oldest reclaimed site (HWY 80 N). Organic matter was higher in limed areas compared to the unlimed reference site only at most recently reclaimed site at Baby Lake. Aboveground plant population health was visibly improved in limed sites compared to unlimed areas. Metal concentrations of iron (Fe) and arsenic (As), total microbial biomasses, gram-negative bacterial, fungal, and eukaryotic biomasses were all significantly increased in the limed soils compared to the unlimed samples. The same trend was observed for the activities of three of the enzymes tested, β-N-acetylglucosaminidase (BG), aryl sulfatase (AS), and glycine aminopeptidase (GAP). Interestingly, strong positive correlations between the levels of soil organic matter, microbial biomasses, and NAGase and ALP activities were observed. Although expensive, aerial liming is effective in restoring inaccessible sites impacted by smelting operations where other methods cannot easily be used.

Optimization and performance analysis of a novel automatic planting-irrigating integrated robot

Soil desertification is a severe environmental problem that seriously threatens the ecological environment and sustainable development. Traditional tree-planting methods face challenges such as insufficient labor force and low efficiency. Based on these problems, this study designed a novel automatic planting-irrigation integrated robot with automatic planting, irrigating, and monitoring functions. The robot obtains land information through laser triangle ranging technology, the camera, and other sensors. Machine vision and deep learning algorithms are applied for image processing and identification to identify the areas suitable for tree planting accurately. The drip irrigation module adopts the DHT11 digital temperature and humidity sensor control switch, which can realize efficient tree planting and watering operation, and ensure the growth of saplings and has a broad application prospect. Our design is meaningful in restraining soil desertification, maintaining the ecological environment, and realizing a sustainable economy.

Research on the Performance and Control Strategy of Electro-Hydraulic Servo System for Selective Hole Digging Tree Planter

Compared to agricultural environments, afforestation sites are more complex, often presenting issues such as undulating and uneven terrain. These conditions lead to instability in hole digging depth and plant spacing during continuous movement, and the hole shape may not meet expectations. Additionally, the hydraulic system exhibits slow response speed and long steady-state time, affecting the quality of sapling planting. To address these issues, this paper designs an intelligent planting control system for intermittent hole digging under continuous dynamic movement, based on a large tree planter. The focus is on studying the dynamic accuracy of the hole digging cylinder to resolve the instability of plant spacing and planting depth in actual planting processes. Firstly, a motion trajectory model of the intermittent hole digging mechanism is established to obtain the relationship between the displacement trajectory of the rotating cutter and the displacements of the floating cylinder and the hole digging cylinder. Secondly, a mathematical model of the electro-hydraulic servo system is established to control the dynamic accuracy of the hole digging operation. Finally, a Simulink simulation model of the system is established to analyze the performance indicators of the hydraulic system during operation using step and sinusoidal excitation signals. The test results show that the displacement of the hydraulic piston rod can ensure a linear extension trend within the range of 0 to 0.4 m, and the extension distance of the hole digging cylinder in the planting system is 0 to 0.35 m, ensuring linear change within this stroke. When the system’s extension command is 1 V, the actual output is 0.6 m, with a relative error of less than 10% compared to the simulation value, indicating that the control strategy can effectively improve the dynamic performance of the system. When the hydraulic system is in a steady-state extension state at 50 to 58.6 s, the relative error with the simulation value is 7.3%, meeting the “double ten indicators” requirement. The research results clearly verify the superior performance of the proposed intelligent control system, and the proposed control strategy has great potential in practical applications, promising to improve afforestation quality by stabilizing planting spacing and planting depth.

Life cycle assessment of common urban trees - The environmental performance of three Mediterranean cities

Given the increasing pressure from extreme events due to climate change, the planting of new trees has become a priority in the political agendas of cities. However, the rush to plant trees often fails to account for the reduced performance and lifespan of trees in heavily urbanized areas and the environmental impact of their production, maintenance, and eventual disposal. By means of the Life Cycle Analysis, this study aims to investigate the potential environmental benefit and impact of trees planted in three European cities located in Mediterranean areas (Perugia, Thessaloniki, and Cascais), that have adhered to the management guidelines of the LIFE Clivut project. The environmental performance of each tree is mainly affected by the tree management operations performed, by the climatic conditions, and by the tree performance in carbon dioxide (CO2) uptake and Particulate matter (PM) capture. The impact assessment obtained by ReCiPe 2016 Endpoint (H) methodology evidenced that the trees' beneficial effects widely overcome the impact of the operations carried out during the tree management. Broadleaved species showed an average environmental performance higher than conifers. The best results have been obtained by Tilia cordata Mill., Quercus ilex L., Populus spp. and Celtis australis L. in the case of broadleaved trees, and by Calocedrus decurrens (Torr.) Florin and Cedrus spp. for Conifers. The results of the Environmental Footprint (EF 3.1) method highlighted the urban trees' potentiality to mitigate Human Health problems and to improve Ecosystem Quality. Future studies may explore other management scenarios to optimize energy and materials use, reduce emissions, hence obtaining an increase of the environmental benefit for the urban areas.

Spatio-temporal soil loss modelling using RUSLE and sediment delivery into a reservoir in a semi-arid region of northern Nigeria

Soil loss is aggravated by uncontrolled deforestation, indiscriminate land clearing for agricultural activities, overgrazing, and urban development that leads to severe soil erosion over the land surface. The main objective of this research is to apply the Revised Universal Soil Loss Equation (RUSLE), in conjunction with remote sensing and GIS, to determine the temporal variation of soil loss from the Gubi watershed in the years 2000 and 2017 and to estimate the sediment delivery into the Gubi reservoir in Northern Nigeria. Datasets of rainfall, soil type, topography, cover management, and support practice were utilized to determine the five RUSLE factors. The research identified five levels of erosion ranging from severe to very low-risk areas. The spatial distribution of erosion hotspots in the catchment area was highlighted. Results revealed increasing levels of erosion from 14,244.31 tons/year in 2000 to 16,792.33 tons/year in 2017. Consequently, the catchment's sediment yield was 6903.65 tons/year and 9172.71 tons/year corresponding to sediment delivery ratios of 48.46 % and 54.62 % in 2000 and 2017 respectively. The sediment inflow into Gubi reservoir was 747.38 tons/year and 950.76 tons/year corresponding to 10.83 % and 10.37 % of the total sediment yield in 2000 and 2017 respectively. Soil erosion vulnerability index maps were produced and the erosion is expected to increase with time as agricultural activities and deforestation continue to occur. The sediment deposits have the potential to reduce the designed life of the reservoir. Best management practices, such as tree planting, mulching, and contour ridging are recommended for soil conservation. There is a need to assess the reservoir sediment deposits so that measures can be taken to maintain the reservoir operations properly.

Assessing Land-Cover Changes in the Natural Park ‘Fragas do Eume’ over the Last 25 Years: Insights from Remote Sensing and Machine Learning

The ‘Fragas do Eume’ Natural Park includes one of the best-preserved Atlantic forests in Europe. These forests are part of the Natura 2000 Network. This scientific study focuses on analysing land-cover changes in the ‘Fragas do Eume’ Natural Park (NW Spain) over a 25-year period, from 1997 to 2022, using machine learning techniques for the classification of satellite images. Several image processing operations were carried out to correct radiometry, followed by supervised classification techniques with previously defined training areas. Five multispectral indices were used to improve classification accuracy, and their correlation was evaluated. Land-cover changes were analysed, with special attention to the transitions between eucalyptus plantations and native deciduous forests. A significant increase in eucalyptus plantations (48.2%) (Eucalyptus globulus Labill.) was observed, while native deciduous forests experienced a decrease in their extent (17.6%). This transformation of the landscape affected not only these two habitats, but also cropland and scrubland areas, both of which increased. Our results suggest that the lack of effective conservation policies and the economic interest of fast-growing tree plantations could explain the loss of native deciduous forests. The results highlight the need to implement pro-active and sustainable management measures to protect these natural forest ecosystems in the ‘Fragas do Eume’ Natural Park.

Primary productivity regulates rhizosphere soil organic carbon: Evidence from a chronosequence of subtropical Chinese fir (Cunninghamia lanceolata) plantation.

Tree plantations worldwide are a large terrestrial carbon sink. Previous studies on the carbon sequestration capacity of plantations mainly focused on tree biomass carbon sequestration, but the importance of soil organic carbon (SOC) was relatively unclear. Living root carbon inputs influence SOC via plant-microbe interactions in the rhizosphere and play an essential role in nutrient cycling. Here, we compared SOC, including its fractions, microbial properties, and major nutrients in rhizosphere and bulk soils, and examined their relationships to net primary productivity (NPP) across three developmental stages of Chinese fir (Cunninghamia lanceolata) plantations (6, 18, and 42 years old) in subtropical China. Although NPP differed among the three plantations, SOC concentration in bulk soils did not vary significantly among them. However, SOC concentration and labile C pool I and recalcitrant C pool in rhizosphere soils were significantly (p < 0.05) higher in the young (6-year) and mature (42-year) plantations, both of which had lower (p < 0.05) NPP (-37.71 % and - 42.67 %) compared to the middle-aged (18-year) plantation, suggesting a decoupling of NPP from rhizosphere SOC in the plantations. The decoupling of NPP from rhizosphere SOC concentrations may be driven by nitrogen (N) and phosphorus (P) tree growth requirements, belowground C allocation, and resultant microbial activity in this highly weathered subtropical soil. Our study provides field-based evidence suggesting that rhizosphere SOC changes are primarily regulated by net primary production in subtropical forest plantations. We propose that accurate predictions of SOC dynamics in forest plantations require an improved understanding of rhizosphere processes during plantation development.

Resilience underground: Understanding earthworm biomass responses to land use changes in the tropics

Soil biodiversity, like terrestrial biodiversity, is currently under threat by changes in land use. Intensively managed farming activities with agrochemicals have degraded both soil biodiversity and health. However, little is known about how these changes in land use affect the distribution of earthworm biomass in Southeast Asia. We conducted earthworm sampling across multiple habitats, including lowland forests, exotic monoculture plantations (e.g., oil palm and rubber tree), and agroforestry orchards. To survey earthworm populations, we excavated the top 30 cm of soil at 18 sites encompassing 399 plots distributed across natural and human-modified ecosystems in Selangor and Negeri Sembilan, Peninsular Malaysia. We found that earthworm abundance was negatively related to increasing soil compaction, leaf litter weight, soil pH, and undergrowth height, whereas it was positively associated with increasing undergrowth and canopy cover. Our findings demonstrated that agroforestry orchards, rubber tree plantations, and mature oil palm plantations had higher earthworm abundance than those in logged lowland forests. Earthworm abundance in unlogged lowland forests and young oil palm plantations, on the other hand, was lower than in logged lowland forests. Overall earthworm weight was greater in rubber tree plantations, agroforestry orchards, mature oil palm plantations, and unlogged lowland forests than those in logged lowland forests, while young oil palm plantations exhibited lower earthworm weight than logged lowland forests. Our data indicate that increases in soil compaction and leaf litter weight were associated with decreased earthworm weight. These results demonstrate the importance of site-level habitat management for maintaining healthy earthworm populations and soil biodiversity.

Spatiotemporal Prediction of Greenhouse Gas Emissions from Rubber Wood Furniture Industry, Taking Hainan as the Case

The rubber wood furniture industry chain, including planting and manufacturing subsystems, emits significant greenhouse gases (GHGs), meanwhile, has huge carbon emission reduction potential. However, quite few studies have taken the whole industry chain GHGs into consideration, especially assessing and modelling those from rubber tree planting to furniture manufacturing. We took the rubber wood furniture of Hainan province as the case, explored its whole life cycle GHGs from cradle-to-gate and predicted the potential GHGs from 2031 to 2062. This study is fully based on field survey and sampling data, including that of the rubber tree planting (40-year cycle) and furniture manufacturing. The results reveal: (1) Whole industry chain of rubber wood furniture emits 3.27×106 kgCO2-eq GHGs per 20,000t rubber logs consuming, where the planting accounts the most (88.20%). Transport and electricity consumption are the main GHGs sources of planting and manufacturing subsystems respectively; (2) The whole life-cycle GHGs of rubber wood furniture in 2023 of Hainan is 2.07×107 kgCO2-eq, which mainly come from Danzhou (24.74%), Haikou (19.55%), and Qiongzhong (15.79%); (3) The total GHGs from the rubber wood furniture industry in Hainan from 2031 to 2062 are 210 MtCO2-eq and 129 MtCO2-eq respectively, without or with felling restriction. The changes of GHGs from 2051 to 2062 are caused by the regional center shift of planting gravity; (4) Improving energy use efficiency and optimizing the location of furniture factories would reduce GHGs. This study can provide empirical support for the low carbon sustainable transformation of the rubber wood furniture industry worldwide.

Comparison between artificial restoration and natural recovery in vegetation regrowth following high-frequency fire disturbances in the Hengduan Mountains, Southwest China

The Hengduan Mountains in Southwest China are currently facing a recurring and escalating threat of forest fires, posing a significant challenge to vegetation restoration efforts given the ecological value of this region. However, the effects of artificial restoration compared to natural regeneration on vegetation recovery dynamics have been less explored. This study focused on two sites in the Hengduan Mountains, primarily composed of conifer forests. One site employed a mix of artificial restoration measures, including tree planting, aerial grass seeding, and fertilizer application. The other site, which is relatively drier and colder, relied on natural regeneration. Four fire events in these two sites were compared to examine the effects of artificial restoration on vegetation recovery using remotely sensed data from Landsat and MODIS. Fire severity was classified using the differenced Normalized Burn Ratio (dNBR) and validated with field samples. Vegetation greenness loss and recovery trajectory were quantified using the near-infrared reflectance of vegetation (NIRv). The effects of artificial restoration were further analyzed after employing unburnt controls to minimize the impact of climate fluctuations. Results showed that fire severity mapping achieved an overall accuracy of 82%. The average NIRv loss across the four fires was 30%, 49%, and 69% in areas of low, moderate, and high severity, respectively. In low severity areas, natural and artificial recovery rates were similar, at 21% and 26% respectively, three years post-fire. In moderate severity areas, artificial restoration achieved a 46% recovery rate compared to 31% for natural recovery. In high severity areas, artificial restoration resulted in a 63% recovery rate versus 45% for natural recovery. Although the differences in recovery patterns may also be attributed to inherent variations in the vegetation composition, physical environment, and their interactions, this study suggests that high severity areas benefit significantly from artificial intervention for rapid recovery. Future studies should include more controlled experiments at the plot scale to further elucidate the processes of vegetation response to different artificial restoration measures.

Morphological and Germination Characteristics of Alhagi maurorum Boiss. and Salsola richteri Kar. Seeds Distributed in the Karakum Desert of Turkmenistan

The Karakum Desert is the largest desert in Turkmenistan and covers a significant part of Central Asia. This desert is home to plant species that can adapt to hot, dry, and barren conditions. During the summer months, the Karakum Desert can get extremely hot, with temperatures reaching up to 50 °C, while in winter, it can drop to -20 °C. Therefore, the desert conditions significant seasonal temperature differences. In winter, rainfall is very low, snow rarely falls, and quickly melts. Afghan winds have an impact on the desert vegetation. The desert vegetation mainly consists of short grasses and woody shrubs. Despite the scarcity of rainfall and high temperatures during the summer months, steppe plants have generally been able to adapt to the harsh conditions of the desert. There are also species that have adapted to the desert climate, such as Alhagi maurorum Boiss., Haloxylon persicum Bunge, Haloxylon aphyllum (Minkw.) Iljin), Solanum nigrum L., and Salsola richteri Kar. These plants are highly valuable in terms of nutrition for animals and are used as winter animal feed in rural areas. In this study, the seed and germination characteristics of Alhagi maurorum Boiss. and Salsola richteri Kar, which are tree and shrub-like plants that can adapt to Karakum Desert conditions, were examined. In laboratory study, the morphological characteristics of the seeds were determined, and vitality and germination tests were conducted. Information was obtained about the germination adaptation of these plants in desert ecosystems. As a result of the study, it was determined that S. richteri had a very low rate of viable seeds and no germination, while the germination process of Alhagi maurorum could take a considerably long time.

Impact of ENVI-met-Based Road Greening Design on Thermal Comfort and PM2.5 Concentration in Hot–Humid Areas

Road greening markedly impacts road thermal comfort and air quality. However, previous studies have primarily focused on thermal comfort or PM2.5 individually, with relatively few addressing both aspects comprehensively, particularly in humid regions. This study combined field measurements and simulations. It employed physiological equivalent temperature (PET) and quantified the horizontal distribution of particulate matter 2.5 (PM2.5). The research examines the effects of planting spacing, tree species, and tree–shrub combinations on pedestrian walkways in humid climates during both summer and winter. Using measured tree data and road PM2.5, a plant model was established and pollution emission parameters were set to validate the effectiveness of the ENVI-met through fitting simulations under various scenarios. The results indicated that (1) plant spacing for trees influenced both the road thermal environment and PM2.5 levels. Smaller spacing improved thermal conditions but increased PM2.5. (2) trees with large canopies and high leaf area indices (LAIs) notably enhanced thermal comfort, while those with smaller canopies and dense understories facilitated PM2.5 dispersion. The 3 m spacing resulted in a maximum absolute PM2.5 concentration difference (C) of 5.05 μg/m3 in summer and a maximum mean absolute PM2.5 concentration difference (M) in the downwind region of 2.13 μg/m3 in winter. (3) Combining trees with shrubs moderately improved pedestrian thermal comfort. However, taller shrubs elevated PM2.5 concentrations on walkways; heights ranging from 1.5 m to 2 m in summer showed higher C values of 5.38 μg/m3 and 5.37 μg/m3. This study provides references and new perspectives for the optimization of roadway greening design in humid areas in China.

Carbon sequestration potential of tree planting in China

China’s large-scale tree planting programs are critical for achieving its carbon neutrality by 2060, but determining where and how to plant trees for maximum carbon sequestration has not been rigorously assessed. Here, we developed a comprehensive machine learning framework that integrates diverse environmental variables to quantify tree growth suitability and its relationship with tree numbers. Then, their correlations with biomass carbon stocks were robustly established. Carbon sink potentials were mapped in distinct tree-planting scenarios. Under one of them aligned with China’s ecosystem management policy, 44.7 billion trees could be planted, increasing forest stock by 9.6 ± 0.8 billion m³ and sequestering 5.9 ± 0.5 PgC equivalent to double China’s 2020 industrial CO2 emissions. We found that tree densification within existing forests is an economically viable and effective strategy and so it should be a priority in future large-scale planting programs.