Search Results (21)

Topsoil organic carbon (SOC, 0–20 cm) is crucial for terrestrial carbon stocks and the global carbon cycle. This study integrated field survey data, re-analysis climatic data, and remote sensing-derived environmental factors to examine SOC distribution and its drivers across forest types on Hainan Island using machine learning models and statistical analysis. The results showed that univariate analysis had limited explanatory power for forest SOC, with terrestrial plantations exhibiting significantly lower SOC than mangroves and natural forests. For mangroves, vapor pressure deficit (VPD) was the most influential factor, followed by precipitation (PRE), the normalized difference vegetation index (NDVI), and forest age; meanwhile, for terrestrial forests, VPD, altitude, PRE, and NDVI were vital drivers. The optimal models demonstrated relatively stronger predictive performance (R² = 0.71 for mangroves; R² = 0.81 for terrestrial forests). Mangroves showed higher average SOC (27.91 g/kg) than terrestrial forests (15.82 g/kg), while higher concentrations in the central–western region were attributed to natural terrestrial forests. This study reveals the spatial variation patterns of forest SOC and its environmental regulation mechanisms on Hainan Island, providing important references for forest carbon stock management and environmental protection. Full article

Poplars are crucial for timber supply and ecological protection in China. Enhancing the growth of poplar plantations and improving soil fertility in arid, and semi-arid poor soil regions are key aspects of sustainable forest management. Fertilization (FTL) and drip irrigation (DI) are among the most widely used methods globally for increasing yield and soil productivity. This study conducted field experiments on FTL and DI in a 10-year-old Populus × canadensis ‘Zhongliao 1’ (cultivation varieties of P. canadensis in northern China) plantation. DI limits were set according to soil moisture at 60% (S1), 70% (S2), and 80% (S3) of field capacity; nitrogen FTL rates were set at 100% of the baseline fertilization amount (100% BFA, N 643.20 g·year⁻¹, P 473.37 g·year⁻¹, and K 492.29 g·year⁻¹) (F1), 70% BFA (F2), 130% BFA (F3), and 160% BFA (F4). The treatments of drip irrigation and fertigation (DIF) were H1 (100% BFA, 60% FC), H2 (100% BFA, 80% FC), H3 (160% BFA, 60% FC), and H4 (160% BFA, 80% FC), along with a control group (CK) without any management, totaling 12 experimental combinations. The results showed that the H4 had the most significant promoting effect on the height, DBH, and volume increments. All treatments had little effect on the soil bulk density of the plantation but significantly impacted soil capillary porosity and pH. Compared to DI, soil nutrient and organic matter content were more sensitive to FTL. Appropriate FTL and DI can increase soil sucrase activity. Soil urease activity tended to increase with higher FTL rates, and higher DI levels also positively influenced urease activity. Excessive or insufficient soil moisture and nutrients negatively impacted soil cellulase and catalase activities. Correlation analysis revealed no significant correlation between the growth of P. × canadensis ‘Zhongliao 1’ and soil nutrient content, but significant or highly significant correlations existed between growth and soil porosity and related enzyme activities. Comprehensive evaluation using a membership function indicated that high FTL levels (F4) were more conducive to the simultaneous improvement of the growth and soil fertility of the plantation, followed by H4 and F1, suggesting that high FTL is the key factor affecting the growth of 10-year-old P. × canadensis ‘Zhongliao 1’ plantations and the restoration of stand productivity, with moisture being secondary. Full article

Some natural rubber farmers mistakenly equate the ecological functions of rubber plantations with those of primary forests. This cognitive bias can hinder pesticide reduction efforts. Meanwhile, natural rubber farmers gain security through price insurance, which helps them adopt a long-term perspective on environmental protection, mitigating the negative impact of cognitive biases on pesticide use decisions. However, existing research often overlooks the influence of ecological cognitive bias on pesticide reduction and the moderating role of price insurance satisfaction. This study utilizes field survey data from Hainan and employs logit models and double machine learning models to empirically analyze the impact of ecological cognitive bias on pesticide reduction among natural rubber farmers. It further tests the underlying mechanisms using moderation models. The results indicate that (1) ecological cognitive bias negatively affects pesticide reduction among natural rubber farmers, and (2) price insurance satisfaction mitigates the impact of ecological cognitive bias on pesticide reduction. Based on these findings, the government should enhance education and training to raise ecological awareness among natural rubber farmers and reduce ecological cognitive biases. Disseminating knowledge about price insurance and establishing a comprehensive insurance system can secure farmers’ income and promote the rational use of pesticides. Full article

Maritime forests are coastal ecosystems that stabilize coastlines, recharge aquifers, and provide protection against storm surges. The range of these forests has been decreasing due to threats such as urban expansion, clearing for agriculture, climate change, and an influx of native but competitive loblolly pine (Pinus taeda L.) from pine plantations. To restore maritime forests, southern live oak (Quercus virginiana Mill.) should be established as the dominant canopy species; however, knowledge of how to grow live oak in a restoration setting is limited. We planted southern live oak seedlings into a clearcut experimental site that was formerly a loblolly pine plantation. Our goal was to test how planting density (1, 2, or 3 m), mulch, and fertilization at planting impacted the initial growth of seedlings over the course of four growing seasons. The application of fertilizer had an initial positive effect on seedling diameter (36%) after the first growing season. The application of mulch increased seedling height in years 2 through 4 (25.6% to 22.7%), diameter in years 3 and 4 (20.9% to 19.3%), and crown width in year four (8.5%). Planting density had no consistent effect over the first four years. These results demonstrate the potential benefits of incorporating fertilizer and mulch into restoration prescriptions to promote seedling field establishment. Planting density should continue to be monitored through canopy closure for potential effects of plant facilitation. Integrating silvicultural treatments such as planting density, soil amendments, and vegetation control may inform cost-effective management recommendations for maritime forest restoration. Full article

The rapid and accurate estimation of aboveground forest phytomass remains a challenging research task. In general, methods for estimating phytomass fall mainly into the category of field measurements performed by ground-based methods, but approaches based on remote sensing and ecological modelling have been increasingly applied. The aim is to develop the scientific and methodological framework for the remote sensing estimation of qualitative and quantitative characteristics of forest stands, using the combination of surveys and machine learning models to determine phytomass of forest stands and calculate the carbon balance. Even-aged stands of different tree species growing in the forest steppe zone of the East European Plain were chosen as test objects. We have applied the modernized methodological approaches to compare and integrate forest and tree stand characteristics obtained by ground-based and UAV-based comprehensive surveys; additionally, we developed computer vision models and methods for determining the same characteristics by remote sensing methods. The key advantage of the proposed methodology for remote monitoring and carbon balance control over existing analogues is the minimization of the amount of groundwork and, consequently, the reduction inlabor costs without loss of information quality. Reliable data on phytomass volumes will allow for operational control of the forest carbon storage, which is essential for decision-making processes. This is important for the environmental monitoring of forests and green spaces of various economic categories. The proposed methodology is necessary for the monitoring and control of ecological–climatic and anthropogenic–technogenic transformations in various landscapes. The development is useful for organizing the management of ecosystems, environmental protection, and managing the recreational and economic resources of landscapes with natural forests and forest plantations. Full article

In this study, agroforestry systems (AFSs) are represented by zonal type using the example of agricultural lands of the administrative districts of the Volgograd region for the first time. The average percentage of forest cover in the territories for these categories of land was 0.9%, with the following distribution by zone: real steppe—1.3%; dry steppe—0.97%; and semidesert—0.6%. Cartographic analysis of the spatial distribution of areas of artificial forest plantations, presented in the form of background cartograms, showed the greatest spatial asymmetry and variability in the forest cover index in the semidesert zone (As = 1.68; Ex = −4.08). This is due to the large variation in indicators by occupied space, namely AFS, agricultural land, and arable land. The calculated area of arable land under AFS protection averaged 35% for the region, with the following distribution by zone: real steppe—47% of the area of the zone; dry steppe—22%; and semidesert—82%. The author’s methodological approach presents the exposed AFS area of arable land as open and closed territories. The open territory of the spring period (March) is land at risk of deflation since it is completely free of plants (black fallows, areas covered by spring crops, and tilled crops). It makes up 67% of the exposed area of AFSs. The annual removal of soil from this area of the region was calculated via mathematical analysis. It amounted to 3.08 × 10⁷ tons. Analysis of the AFS species composition showed the following distribution of species: deciduous species—86%; mixed species—8%; and coniferous—6%. This model can be applied to many arid areas to calculate deflationary losses and the amount of additional AFSs needed. Full article

Over the years, Eucalyptus plantations have rapidly expanded in Sarawak, Malaysia, accounting for 19% of the total forest plantation area. In a routine forest health surveillance conducted in 2022 at Sarawak, Malaysia, tree stands of Eucalyptus urograndis (Eucalyptus grandis × Eucalyptus urophylla hybrid) were detected with symptoms of stem canker disease caused by Chrysoporthe infection. Given the limited information on the chemical control of Chrysoporthe stem canker disease, there is a growing need to develop effective chemical control strategies to protect and cure Chrysoporthe infection on E. urograndis trees. Therefore, this study aimed to identify the causal pathogen of this stem canker disease in 7-year-old E. urograndis trees in Sarawak, Malaysia, and evaluate the efficacy of various fungicides as curative or protectant treatments on canker infection using artificial inoculation methods. Fungal isolates were first collected and subjected to molecular identification and pathogenicity analysis. Then, in vitro efficacy tests were evaluated using five licensed fungicides: thiram, prochloraz manganese chloride, copper hydroxide, dimethomorph, and mancozeb. Subsequently, the performance of these fungicides was assessed through preventive and curative field experiments on 10-year-old E. urograndis trees using the artificial inoculation technique. Based on the morphological and phylogenetic analysis of the ITS1/ITS4, β-tubulin 2 (BT2), and the combined ITS1/ITS4 and BT2 sequences extracted from 20 fungal isolates, Chrysoporthe deuterocubensis was identified as the causal pathogen of the canker disease, with isolate CHRY18 recording the highest virulence. The in vitro efficacy tests showed that prochloraz manganese chloride achieved 100% inhibition against C. deuterocubensis at 1.0 mg/mL. In the preventive experiment, thiram significantly inhibited C. deuterocubensis infection, yielding the shortest lesion length (19.40 mm) compared to the non-treated control (47.48 mm) at 20 weeks post-inoculation. In the curative experiment, a significant reduction of 54.7% in lesion length was observed in inoculated symptomatic trees after 20 weeks of post-fungicide treatment with copper hydroxide. In conclusion, this study demonstrated prochloraz manganese chloride, thiram, and copper hydroxide as effective chemical controls of C. deuterocubensis stem canker on E. urograndis. Full article

The aim of this study was to study the effectiveness and economic efficiency of the impact of agroforestry complexes on the adaptation of agriculture to climate change in the south of the Russian Plain. It has been established that this manifests quantitatively in a significant decrease (by almost a third) in the area of wind-destroyed lands and drought-dead crops in farms protected by forest strips compared with open agricultural territories. The calculation of direct damage prevented by protective forest plantations from degradation and loss of soil fertility as a result of dust storms and indirect damage prevented by protective forest plantations from crop loss as a result of extreme droughts shows that the total amount of remuneration received by farmers from agroforestry in connection with the placement of a forest-forming element in their fields is EUR 317–1239 ha⁻¹ year⁻¹. This value is the contribution of agroforestry to adaptation to climate change and is subject to zonal dynamics—it depends on natural and climatic conditions. The application developed as part of this research has value for decision makers, since it allows for preliminary assessment of the effectiveness and efficiency of agroforestry for various areas of farms and various natural zones. Full article

In Hong Kong, as in many tropical areas, grasslands are maintained by fire on disturbed and abandoned land. However, Hong Kong’s native forests are regenerating in many areas, alongside frequent burning of the hillsides, and are in different stages of structural succession to closed canopy forest patches. Understanding the major determinants of secondary succession is a vital input to forest management policies. Given the importance of forests for biodiversity conservation, watershed protection and carbon cycling. This study examines the relationship between burning regimes and structural forest succession over 42 years from 1973 to 2015, using an archive of satellite images, aerial photographs and field plot data. Overlay of a fire frequency map with maps of forest structural classes at different dates indicates the number of fires undergone by each successional class as well as the time taken to progress from one class to another under different fire regimes. Results indicate that the native sub-tropical evergreen forests, which are naturally fire intolerant, can regenerate alongside moderate burning, and once the shrub stage is reached, succession to closed forest is relatively rapid and can occur within 13 years. More than one burn, however, is more destructive, and twice-burnt areas were seen to have only one-third of the woody biomass of once-burnt plots. The most frequent fires occurred in areas where mono-cultural plantations had been destroyed by disease in the 1960s and were subsequently invaded by grasslands. These former plantation areas remained in early successional stages of grass and open shrubland by 2015. Other plantations from the 1970s and 1980s remain as plantations today and have acted as a barrier to natural forest succession, attesting to the greater effectiveness of fire control over re-afforestation measures. Full article

The high value of black truffle recompenses the slow growth of the fungus when established in the field. Adding a secondary crop, such as medicinal and aromatic plants (MAPs), could further enhance the sustainability of truffle production agro-forest systems. The dual cultures of ectomycorrhizal truffle-oak seedlings and MAPs (lavender, thyme, and sage) previously inoculated and non-inoculated with native arbuscular mycorrhizal fungi (AMF), were established to evaluate plant–fungi relationships. After 12 months in a shadehouse, plants’ growth, mycorrhizal colonization, and extraradical soil mycelium (both of Tuber melanosporum and AMF) were measured. Overall, truffle-oaks’ growth was negatively affected by the presence of MAPs, especially when inoculated with AMF. In turn, the presence of truffle-oaks barely affected the co-cultured MAPs, and only lavenders showed a significant growth reduction. All AMF-inoculated MAPs showed higher shoot and root biomass than non-inoculated ones. Compared to truffle-oaks growing alone, the presence of co-cultured MAPs, especially when they were AMF-inoculated, significantly decreased both the ectomycorrhizas and soil mycelium of T. melanosporum. These results reveal the strong competition between AMF and T. melanosporum and warn about the need for the protection of intercropping plants and their associated symbiotic fungi to avoid reciprocal counterproductive effects in mixed truffle-oak–AMF–MAP plantations. Full article

This study was carried out to clarify the response of photosynthesis physiology of Caragana intermedia, an excellent tree species for wind protection and sand fixation, to soil water content (SWC) and to determine the relevant threshold ranges in the sandy lands of Qinghai-Tibet Plateau. In this study, based on the three-year forest experiment from 2017a to 2019a, C. intermedia in different afforestation years (2013a, 2011a, 2008a, 2006a, 2001a and 1986a) were selected for experimental analysis, the response process of leaf photosynthesis of C. intermedia to SWC changes was studied, and the physiological mechanism and growth suitability of C. intermedia to adapt to an alpine desert environment were clarified. The results showed that SWC played a critical role in the photosynthesis of C. intermedia in the sandy lands of Qinghai-Tibet Plateau. Afforestation years are negatively correlated with Pn, gs and Tr, but positively correlated with WUE; the longer the afforestation years, the higher demand for soil moisture. Regarding the relative roles of SWC and photosynthetic parameters, we demonstrated that this showed a significant square relationship (p < 0.001), while stomatal closure induced by the photosynthesis decline was important under dryness stress. The no-productivity and no-efficiency water (NPNEW) for the photosynthesis physiology of trees in different afforestation years were 3.31–3.64%; 3.33–4.06%; 3.08–3.63%; 3.36–3.85%; 1.45–4.02% and 3.39–5.50%, and the highest productivity with the highest availability of water (HPHAW) were 6.65–7.19%; 6.74–7.36%; 7.36–7.91%; 6.10–7.51%; 6.57–8.19% and 6.52–8.35%. Plantations in different afforestation years could survive safely in the sandy lands of Qinghai-Tibet Plateau. However, the productivity of trees decreased with the increase length of afforestation years; thus, we should pay attention to their growth status and make timely management adjustments in the future. These results provide important information for theoretical support for the diagnosis of ecological adaptability and field water management of C. intermedia in the sandy lands of Qinghai-Tibet Plateau and provide a reference for the adaptability evaluation and water–carbon cycle simulation of plantations in the sandy lands of Qinghai-Tibet Plateau against the background of global climate change. Full article

Kyunsu township comprises coastal regions and a multitude of small islands covered by vast tropical evergreen and mangrove forests, and a large water body in the Adman Sea of Myanmar. Due to population growth, residents have increasingly expanded their agricultural land areas into natural tropical evergreen and mangrove forests, leading to deforestation. Understanding the processes and consequences of landscape transformation for surrounding ecosystems is crucial for local policy making and for fostering sustainable crop production in this area. Landsat datasets from 1978, 1989, 2000, 2011, and 2020 were used in a time-series post-classification approach to investigate land use land cover (LULC) changes in the Kyunsu township of Southern Myanmar across the last 40 years. Our study also attempted to assess the effects of the transformation of LULC on carbon stocks. Between 1978 and 2020, major LULC changes occurred with the expansion of Paddy Fields (+90%), Plantations (+11%), Open Forests (+81%), Settlement Areas (+115%), Aquaculture Areas (+1594%), and Others (+188%) while the area covered with Closed Forests shrunk by 44% and with Mangrove Forests by 9%. Water Bodies expanded by 0.13%. Our analyses show that between 1978 and 2020 2453 ha of Paddy Fields expanded into Plantations, 1857 ha to Open Forests, and 1146 ha to Mangrove Forests. Additionally, 12,135 ha of Open Forests, 8474 ha of Closed Forests, and 2317 ha of Mangrove Forests became Plantations. Across the 40 year study period, a total of 40,523 ha of Closed Forests were transformed to Open Forests. Our findings show that transformation of agricultural landscapes in the study area significantly affected deforestation and forest degradation of tropical evergreen rain forests and mangrove forests which are vital sources of ecosystem services. These transformations led to estimated losses of carbon stocks between 1978 and 2020 ranged from 89,260–5,106,820 Mg (average of 1,723,250 Mg) in our study area. Our findings call for sustainable resource intensification to increase production efficiency in existing cultivated areas rather than crop land expansion into natural forests. In addition, our data highlight the need for rigorous policies to conserve and protect tropical natural evergreen and mangrove forest, as key local resources providing multiple ecosystem services. Full article

Higher-resolution wall-to-wall carbon monitoring in tropical Africa across a range of woodland types is necessary in reducing uncertainty in the global carbon budget and improving accounting for Reducing Emissions from Deforestation and forest Degradation Plus (REDD+). This study uses Sentinel-2 multispectral imagery combined with climatic and edaphic variables to estimate the regional distribution of aboveground biomass (AGB) for the year 2020 over the Cross River State, a tropical forest region in Nigeria, using random forest (RF) machine learning. Forest inventory plots were collected over the whole state for training and testing of the RF algorithm, and spread over undisturbed and disturbed tropical forests, and woodlands in croplands and plantations. The maximum AGB plot was estimated to be 588 t/ha with an average of 121.98 t/ha across the entire Cross River State. AGB estimated using random forest yielded an R² of 0.88, RMSE of 40.9 t/ha, a relRMSE of 30%, bias of +7.5 t/ha and a total woody regional AGB of 0.246 Pg for the Cross River State. These results compare favorably to previous tropical AGB products; with total AGB of 0.290, 0.253, 0.330 and 0.124 Pg, relRMSE of 49.69, 57.09, 24.06 and 56.24% and −41, −48, −17 and −50 t/ha bias over the Cross River State for the Saatchi, Baccini, Avitabile and ESA CCI maps, respectively. These are all compared to the current REDD+ estimate of total AGB over the Cross River State of 0.268 Pg. This study shows that obtaining independent reference plot datasets, from a variety of woodland cover types, can reduce uncertainties in local to regional AGB estimation compared with those products which have limited tropical African and Nigerian woodland reference plots. Though REDD+ biomass in the region is relatively larger than the estimates of this study, REDD+ provided only regional biomass rather than pixel-based biomass and used estimated tree height rather than the actual tree height measurement in the field. These may cast doubt on the accuracy of the estimated biomass by REDD+. These give the biomass map of this current study a comparative advantage over others. The 20 m wall-to-wall biomass map of this study could be used as a baseline for REDD+ monitoring, evaluation, and reporting for equitable distribution of payment for carbon protection benefits and its management. Full article

The topical issues for elaboration of new approaches to grow English oak (Quercus robur L.) seedlings with the purpose to establish sustainable plantations in forest-steppe Ukraine. The goal of the research is to elaborate a technology for growing the containerized seedlings of English oak. Oaks are among the most common tree species found throughout the world. Throughout history, oaks have provided humans and wildlife with shelter, and food. However Ukrainian forests face multiple natural and anthropogenic pressures. Climate change generates a particular threat for Ukrainian forests and stability of agroforestry landscapes. This paper considers the impacts of expected climate change on vulnerability of Ukrainian forests, especially for oaks. In response to forest depletion, stricter forest management practices emerged to replant, protect and maintain forest cover and the multi-functionality of forests in terms of wood production. Even though oaks have wide ecological amplitudes of suitable growing conditions, Ukrainian forests dominated by oaks often fail to regenerate naturally. In this regard, it is necessary to increase the cultivation of crops in containers. Field germination of oak seedlings in containers with different substrate composition was identified in the case study in the conditions of Ukrainian Left-bank Forest-Steppe. The height and diameter values of the seedlings were investigated and summarized including the influence of the root ball substrate composition. We tested different compositions of the substrate containing low-land peat, which is rich in nutrients and mixtures with different ratios of soil, humus and sawdust. The advantage over the control in germination ability, survival and condition has been experimentally proved for variants with the use of peat in the substrate and, to a large extent, for the variant with the use of soil, humus and sawdust. Among tested substrates, the peat-containing variant with equal portions of dark gray wooded middle loamy soil and peat (peat:soil = 1:1) and the variant of the three-component mixture soil:humus:sawdust = 4:2:1 are the most balanced in the basic soil parameters (acidity and nutrient content). In the same time they are the best among the studied ones for the productive growing of English oak seedlings. The use of containerized planting stock allowed foresters not only to significantly extend the terms of forest planting, which is particularly topical for Ukraine, but also to increase the root-taking of planting stock up to nearly 100% in forest-cultivated areas. Full article

An extreme landscape is a spatially heterogeneous area with unusual topography that is prone to natural disasters but still exhibits interrelated structures and functions. One of the important functions of an extreme landscape is its ecological function. This study aimed to determine the structure and reveal the ecological functions of an extreme landscape in a tropical region of West Java, with special reference to Rongga Sub-district. The method used was a combination of remote sensing techniques and geographic information systems, which were required to process, analyze, and interpret Landsat 8 OLI/TIRS data. The landscape structure was quantified by landscape metrics, after which an analysis of ecological functions was carried out based on the constituent elements of the landscape. The results showed that the landscape structure of Rongga Sub-district consists of various elements of agroforestry land, open fields, settlements, shrubs, plantations, and rainfed and irrigated rice fields. Additionally, secondary forest land acted as a landscape matrix where rivers crossed as natural corridors. The amount of each element varied; agroforestry land had the highest value, indicating that this element showed a high degree of human intervention. Each patch was adjacent to other patch types, and the landscape diversity was quite high. The extreme topography of Rongga Sub-district supports the landscape connectivity and consequently the presence of wild animals in this area. Therefore, Rongga Sub-district has an essential ecological function as a refuge for protected animals living in non-conservation areas. Full article