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Background and Aim: The productivity of sheep in humid tropical plantation areas relies on their ability to adapt. Oil palm plantations serve as potential grazing lands for livestock. This study aimed to identify Garut sheep adaptations in oil palm and rubber plantations of the Garut district, West Java, Indonesia. Materials and Methods: The total number of sheep used was 103 as the object of this study. Each individual of sheep was used for several different observations, including: Physiological assessment using 24 sheep of various ages, molecular analysis of heat stress using 31 sheep, worm egg count using 59 sheep, and for morphological assessment using 98 sheep. A general linear model was employed to analyze rectal temperature (RT), heart rate (HR), respiratory rate, number of eggs in each gram of sample feces, body weight (BW), body condition score, and morphometric measurements according to age and sex. Forage was compared between oil palm and rubber plantations during the vegetation analysis. Results: RT, HR, and panting frequency were significantly (p < 0.05) affected by the age and sex of the sheep. The mutation was found in the coding region of the HSP70 gene, which is approximately 232 bp long. Fecal eggs were found in 99% of the fecal samples, consisting of 100% Strongyle eggs and 1.75% Moniezia eggs. BW, body condition score, shoulder height, body length, pelvic height, chest circumference, and number of eggs were significantly affected (p < 0.05) by the age and sex of the sheep. The average fresh matter of vegetation under the plantation was 248.69 ± 120.94 g/m² and 718.15 ± 249.93 g/m² for oil palm and rubber plantations, respectively. Conclusion: Garut sheep were adapted to oil palm and rubber plantations in the humid tropical region. Plantations are potential sources of sheep grazing and roughage. Further research is needed regarding the consumption of forages in oil palm and rubber plantations. [ABSTRACT FROM AUTHOR]

The precise acquisition of phenotypic parameters for individual trees in plantation forests is important for forest management and resource exploration. The use of Light-Detection and Ranging (LiDAR) technology mounted on Unmanned Aerial Vehicles (UAVs) has become a critical method for forest resource monitoring. Achieving the accurate segmentation of individual tree crowns (ITCs) from UAV LiDAR data remains a significant technical challenge, especially in broad-leaved plantations such as rubber plantations. In this study, we designed an individual tree segmentation framework applicable to dense rubber plantations with complex canopy structures. First, the feature extraction module of PointNet++ was enhanced to precisely extract understory branches. Then, a graph-based segmentation algorithm focusing on the extracted branch and trunk points was designed to segment the point cloud of the rubber plantation. During the segmentation process, a directed acyclic graph is constructed using components generated through grey image clustering in the forest. The edge weights in this graph are determined according to scores calculated using the topologies and heights of the components. Subsequently, ITC segmentation is performed by trimming the edges of the graph to obtain multiple subgraphs representing individual trees. Four different plots were selected to validate the effectiveness of our method, and the widths obtained from our segmented ITCs were compared with the field measurement. As results, the improved PointNet++ achieved an average recall of 94.6% for tree trunk detection, along with an average precision of 96.2%. The accuracy of tree-crown segmentation in the four plots achieved maximal and minimal R2 values of 98.2% and 92.5%, respectively. Further comparative analysis revealed that our method outperforms traditional methods in terms of segmentation accuracy, even in rubber plantations characterized by dense canopies with indistinct boundaries. Thus, our algorithm exhibits great potential for the accurate segmentation of rubber trees, facilitating the acquisition of structural information critical to rubber plantation management. [ABSTRACT FROM AUTHOR]

It is well known that long-term chemicalised agricultural practices harmfully affect soil health and prevent sustainable management of fertility in crop fields, including that of plantation crops. Accordingly, an investigation was carried out to check how soil fertility characteristics such as soil pH, soil mineral nutrient and organic carbon content are altered in long-term chemicalised rubber plantations of Kerala, located in the ecologically sensitive Western Ghats of South India. Soil fertility status concerning soil types in the Rubber fields (USDA soil orders - suborders) such as Inceptisols - Oxic Dystrudepts (IOD), Ultisols - Ustic Haplohumults (UUH), Ultisols - Typic Kandiustults (UTK) and Mollisols - Pachic Argiustolls (MPA) involving six soil series are critically analysed. A negative impact of long-term chemicalised agriculture was visible in low soil pH and nutrient levels. In general, rubber fields in the region, even in the generally alkaline Mollisols, showed a pH of 6.23. The soils showed reduced nutrient and carbon content and a comparatively poor soil fertility index specific to soil types. The soil available NPK and soil total cations were found to be comparatively low and soil specific. However, rubber fields in Mollisols were significantly higher in STK, STMg, STCa, and STNa while those in Ultisols were significantly higher in SAP and SAK than other soil orders. The Inceptisols were significantly higher in SAN, STP, and soil organic carbon than others. Therefore, balanced fertilizer application concerning soil types per proper soil fertility monitoring has become significant to sustainable soil productivity management in rubber plantations. [ABSTRACT FROM AUTHOR]

The rubber tree is an economically important tree planted in many tropical countries. While rubber planting has improved the livelihoods of growers, it has also resulted in soil degradation. However, systematic studies on assessment of soil health and its management in rubber plantations are limited. The present study explored whether intercropping of Michelia macclurei (an ornamental evergreen tree) in rubber plantation could help conserve soil health compared to traditional monoculture practice with randomised complete block design. The rubber tree density was the same in monoculture and intercropping, with the addition of Michelia macclurei in intercropping. The effects of soil properties and microbial communities was used to analyse two different planting patterns of rubber monoculture and rubber intercropping using soil sampling from field plots. The study investigated variation in soil physical structure, soil moisture, soil nutrients, soil microbes, and enzyme activities in two types of rubber plantations viz. a monoclonal plantation without intercrop (RM) and a plantation with Michelia macclurei as an intercrop (RAS). The results from above study showed an increase in soil organic carbon (SOC), total nitrogen (TN), ammonium nitrogen (AN), available phosphorus (AP), nitrate nitrogen (NN) and total potassium (TK) in plantation with intercrop as compared to monoclonal plantation without intercrop. When comparing the corresponding values of RM to RAS, bacteria and total microbial abundance of RAS increased on average by 75.51% and 48.42%, respectively. In addition, after the transition from rubber monoculture to rubber agroforestry, the annual average of SOC, TN, AP, TK nutrients and pH in soil increased by 10.94%, 4.25%, 14.53%, 1.34% and 9.74%, respectively. Soil water content, soil bulk density and soil porosity were not significantly different between RM and RAS treatments. Sucrase activity and cellulase activity also increased in the RAS intercropping system. These results show that intercropping promotes soil organic matter and microbial communities and enhances soil enzyme activities. These findings indicate that rubber intercropping creates healthy soil environments conducive to tree growth and improves the ecosystem sustainability of rubber plantations. Healthier and stronger rubber trees may increase rubber production and provide sustainable management of plantations in the future. [ABSTRACT FROM AUTHOR]

Rubber plantations are an important component of tropical forest ecosystems and are emerging as crucial contributors to carbon sequestration in the tropics. However, ecosystem respiration (RECO), which constitutes an essential constraint on the carbon fixation capacity of rubber plantations, and its driving mechanisms remains unclear. Therefore, this study developed a data-driven semi-empirical model to simulate rubber plantations RECO utilising eddy covariance flux measurements and was upscaled to Hainan Island using remote sensing images and climatic data. Numerical simulations experiments analysed direct and indirect of climatic factors impacts on rubber plantations RECO. The results showed that the model accurately captured RECO trends and seasonality (R2 = 0.87, RMSE = 1.27 g C m−2 d−1); in the past 19 years, RECO showed a noticeable increase, particularly in the late rainy season and the seasonality of RECO has shown a delayed pattern. The RECO in the central region (52% area) exhibited multimodal enhancement while northern and southern regions (37% area) showed oscillations or decreases. Temporally, RECO is higher in the rainy season compared to the dry season, and spatially, RECO is higher in the southern region than in the northern region. Among the climatic factors, water conditions (rainfall and air humidity) have been emerged as dominant factors (5.38%) influencing RECO, surpassing temperature (3.96%) and radiation (3.81%). In addition, climatic factors make a positive overall contribution during the dry season but perform oppositely in the rainy season. This study offers theoretical and technical insights into high carbon sink management in rubber plantations and carbon sequestration in tropical forests ecosystems. [ABSTRACT FROM AUTHOR]

Rubber plantations are among the most important in the world's tropical regions. They play a positive role in carbon sequestration and in delaying climate change, supplying strategic resources of natural rubber (NR), and aiding in poverty alleviation and rural revitalisation. This paper reviews six methods of research on carbon sinks in rubber plantations: the biomass inventory method, the biomass conversion factor continuous function method, the trade potential of carbon sinks method, the calculation method for carbon storage of rubber latex, the eddy covariance method, and the remote sensing image model method. This study clarifies the carbon sink assessment and enhancement model for rubber plantations and describes the composition of the carbon pool, which includes the aboveground and belowground vegetation biomass carbon pools, litter carbon pool, latex carbon pool, and soil carbon pool. It also examines influencing factors such as tree age, global climate change, and human disturbance, as well as improvement pathways including afforestation, fertilisation, irrigation, and tapping, and evaluation methods like field surveys, positional observations, remote sensing monitoring, and model simulation. Research on carbon sequestration in rubber plantations faces challenges, including the unclear dynamics of carbon sources and sequestration, uncertain spatial and temporal patterns, and the long-term lack of accurate monitoring of carbon sinks and technologies for increasing sinks and reducing emissions. Future research should focus on the methodology of rubber plantation carbon sequestration projects, the dynamics of carbon sequestration, and the spatial allocation pattern of carbon sequestration in rubber plantations. [ABSTRACT FROM AUTHOR]

Given the environmental and socioeconomic challenges associated with monoculture rubber plantations, the Food and Agriculture Organization (FAO) emphasized the importance of utilizing and protecting crop diversity for sustainable development of rubber industry in Thailand. However, the adoption of such technology remains relatively low that makes rubber crop diversity highly controversy in Thailand. Based on data collected from 2,159 rubber households between 2012 and 2014, this study aims to investigate the impacts of crop diversity adoption on the net income of rubber farmers in Thailand by using propensity score matching models. The findings reveal that adopting rubber crop diversity has a statistically significant negative effect on rubber farmers' net income. Specifically, those engaged in rubber crop diversity experience a lower net income per person ranging from − 11,785.29 baht to -10,887.21 baht comparing their counterparts practicing monoculture rubber farming. Furthermore, such significant negative effects are exclusively observed among smallholders and rubber farmers in southern regions. Given the implementation of rubber crop diversity system usually grants environmental benefits to the local eco-systems as positive externalities without market rewards, it is imperative to provide additional incentives and support mechanisms to steam up wider adoption of rubber crop diversity for ensuring long-term sustainability of rubber industry in Thailand. [ABSTRACT FROM AUTHOR]

Settlement expansion and commercial agriculture affect landscape sustainability and ecosystem service provision. Integrated landscape approaches are promoted to negotiate trade-offs between competing land uses and their reconciliation. Incorporating local perceptions of landscape dynamics as basis for such negotiations is particularly relevant for sub-Saharan Africa, where most people depend on natural ecosystems for livelihoods and well-being. This study applied participatory scenario building and spatially explicit simulation to unravel perceptions of the potential impact of rubber and settlement expansion on the provision of selected ecosystem services in southwestern Ghana under a business-as-usual scenario. We collected data in workshops and expert surveys on locally relevant ecosystem services, their indicator values, and the probable land-use transitions. The data was translated into an assessment matrix and integrated into a spatially explicit modeling platform, allowing visualization and comparison of the impact on ecosystem service provision of land-use scenarios under rubber plantation and settlement expansion. The results show the capacity of current (2020) and future land-use patterns to provide locally relevant ecosystem services, indicating a decline in capacity of ecosystem service provisioning in the future compared to the 2020 land-use patterns, a threat to the benefits humans derive from ecosystems. This highlights urgent need for policies and measures to control the drivers of land-use/land-cover change. Furthermore, the results emphasize the importance of diversifying land-use/land-cover types for sustainable landscape development. The paper contributes new insights into how spatially explicit and semi-quantitative methods can make stakeholder perceptions of landscape dynamics explicit as a basis for implementing integrated landscape approaches. [ABSTRACT FROM AUTHOR]

Groundwater resources play an important role in meeting the water needs of agriculture and industry. Therefore, identifying the factors affecting the potential challenges of groundwater resources can be key to proper implementation and management, considered the main goal of the current research. In this study, agricultural groundwater poverty index (AGPI) and industrial groundwater poverty index (IGPI) were developed based on General, Effective, and Data mining methods for the study period 2012–2020 in the West Azerbaijan Province, Iran. Both agricultural and industrial sectors were classified into five categories with 17 and 15 associated variables, respectively. The total scores of AGPI and IGPI were obtained (48.63, 47.80, 49.67) and (33.35, 33.60, 33.37), respectively, for General, Effective, and Data mining methods in the West Azerbaijan Province. In 2012–2020, the qualitative classification of the sustainability status of groundwater resources for the agriculture and industry sectors was at a good and very good level. The crop cultivation patterns of Pea, Beans, and Lentils products require management reforms to avoid the relative unsustainability in groundwater resources. Also, Production of Food and Beverages, Tobacco products, Production of Coke fuel, Oil refineries, and Nuclear fuels, Chemical Products, Rubber and Plastic products, and Non-Metallic Mineral Products could face management challenges in the West Azerbaijan Province. As the agricultural sector puts more pressure on groundwater resources than the industrial sector, it is expected that the southern part of the province will be more affected by water crises in the future. Also, the countries' internal management plans and international relations, such as the Joint Comprehensive Plan of Action (JCPOA), could have a significant impact on the status of their water resources. Due to saving time and money, it is highly recommended to use the Data mining method to develop the AGPI and IGPI in practical projects. The results of current study will have a critical impact on improving and optimizing the performance of implemented groundwater resource management projects in various temporal–spatial levels. [ABSTRACT FROM AUTHOR]

Background: Understanding how landscape characteristics affect animal movement is essential for conservation in human-dominated habitats. A fundamental question is how monoculture agroforests, including rubber and tea plantations, affect wildlife and its movement. Experimental translocations represent an important technique to assess animals' habitat selection while moving through agricultural matrices, especially when complemented with observations of birds' natural movements, and with "control" translocations, in which birds are moved within their natural habitat such as forest. Yet, experimental translocations have been little used for birds outside the Western Hemisphere. Methods: We conducted experimental translocations and home-range measurements on an understory forest specialist, Brown-capped Babbler (BCBA, Pellorneum fuscocapillus), and a forest generalist, Tickell's Blue Flycatcher (TBFL, Cyornis tickelliae). These species were studied in three rubber plantations, which also included some open areas mostly planted with tea, and in three forest reserves of Sri Lanka. Results: Four of the five BCBAs translocated within disturbed habitats (rubber plantations) could not return to their capture locations. However, all four individuals within undisturbed habitats (forest reserves) successfully returned to their point of origin within 10.5 daytime hours. In contrast, all TBFLs returned to their capture locations in both disturbed (n = 7) and undisturbed habitats (n = 3) within 11.3 daytime hours. A Cox-proportional survival model demonstrated that the percentage of rubber cover decreased return time, similar to the effect of open-area cover. The home range surveys (n = 13 for BCBA, n = 10 for TBFL) revealed that very little of the birds' natural home-ranges was covered by rubber (0.2% for BCBA, 13.1% for TBFL at 50% Kernel Density Estimates KDE). Home range size for BCBA was approximately half the size in disturbed habitats compared to undisturbed ones, although there was no significant difference between habitats for TBFL. Conclusions: We conclude that rubber plantations can be impermeable to understory habitat specialist birds, and even generalist species may avoid them long-term. Our findings highlight the potential utility of strips of native vegetation, particularly those featuring understory layers, as corridors to facilitate the movement of forest specialists in landscapes dominated by rubber plantations and other types of disturbed habitats. [ABSTRACT FROM AUTHOR]

Natural rubber is one of the four main raw materials of industry and a globally important strategic material. Rubber plantations with agroforestry attributes have undergone rapid growth in the northern part of mainland Southeast Asia (including Xishuangbanna) since the 1990s, leading to a series of eco-environmental effects on biological diversity, climate change, carbon stocks, and hydrological processes. Accurate, detailed, and updated spatial information on rubber plantations, therefore, is fundamental for developing efficient management strategies. Currently, the booming rubber plantations are being experienced new changes in Xishuangbanna. The commonly used coarser spatial resolution satellite data (e.g., 250-m MODIS and/or 30-m Landsat) have limited applications because most plantations are often small and scattered, especially in the mountainous areas. Here, we developed a straightforward and effective re-normalization of red green normalized difference vegetation index (ReNDI) approach based on finer resolution (10-m) Sentinel-2 imagery, and then mapped the first annual 10-m rubber plantations in the entire Xishuangbanna during 2018–2021. Interestingly, rubber plots no longer expanded as rapidly as in past decades and even decreased slightly. The latest area of rubber plantations was 2514.7 km2, a decrease of 31.9 km2 comparing since 2018, with an average overall accuracy and kappa coefficient of four-year reached up to 95.37 % and 0.90, respectively. Among them, Jinghong city and Menghai county increased by 52.4 km2 and 14.8 km2 respectively, and Mengla county decreased by 99.1 km2. The main area of rubber expansion was around the Jinghong city, where rubber was initially planted. More importantly, owing to pursuing increased economic benefits and requirements of environmental protection, a considerable portion of the rubber encroachment has disappeared, particularly near roads and rivers. Our phenology-based ReNDI algorithm not only enriches the remotely-sensed methods for other industrial plantations mapping, but also provides a new chance to understanding the current patterns of rubber plantations (i.e., increase and decrease), which will contributed to rational planting planning and agroforestry management in the future, especially in the tropics. [ABSTRACT FROM AUTHOR]

This study was designed to estimate the land snail diversity of coastal Karnataka, India, and to compare it with that of the Western Ghats mountain range. Altogether, 23 species of land snails were recorded, of which 18 species were found in coastal Karnataka and 3 species were confined only to Western Ghats. The highest number of land snails were found in national parks, followed by plantations, and the lowest in open areas. Rhachistia praetermissus was confined to the nagabana of Harekala and Rishetia sp. was only seen in home gardens. Among the plantations, land snail diversity was higher in arecanut plantations and lower in rubber plantations. Land snails such as Mariaella dussumieri and Macrochlamys indica were common to most of the visited habitats. Significant correlation between humidity and species richness of land snails indicates that humidity determines the land snail diversity in coastal Karnataka. Reserve forests/National Parks studied encompass more land snail diversity as they provide heterogeneous habitats and suitable ecological niches. Lower diversity of land snails in plantations and open areas compared to the reserve forests can be attributed to lower habitat complexity and anthropogenic disturbances. [ABSTRACT FROM AUTHOR]

Scientific manuring, by adopting balanced nutrition in perennial plantations is the need of hour for increased productivity and addressing global warming by adopting 4 R nutrient stewardship. Continuous use of NPK in perennial crops can lead to deficiency of micronutrients. Therefore, a study was carried out to understand nutrient status of major rubber growing tracts and to formulate a customized nutrient mixture for rubber. A detailed soil fertility assessment and leaf tissue analysis of mature rubber plantations of age group 11-15 years in five agro ecological units (AEU) in Thiruvananthapuram were conducted during the study. Based on this, a multi micronutrient mixture was formulated for rubber and the composition of the mixture was Zn -3.64 %, B -8.04 %, Fe- 2.01 %, Cu- 2.55 % and Mn-3.25 %. For accessing the effect of the mixture, a field experiment was conducted in existing rubber plantation of RRII 105 replanted in 2005 at Aryanad (AEU 14) in randomized block design with seven treatments and three replications, namely general recommendation of NPK at 30:30:30 kg ha-1year-1, soil test based recommendation of NPK at 22:8:21 kg ha-1 year-1, application of multi micronutrient mixture along with soil test based recommendation of NPK at varying levels from 5 to 15 kg ha-1year-1. The treatments had a significant effect on dry rubber content (DRC). For the post monsoon, summer, and annual period, the highest DRC was noticed in 15 kg ha-1 of the mixture applied plot which was on par with 7.5 kg ha-1 applied plot. Application of micronutrient mixture resulted in enhancement of different micronutrient pools and enriched nutrient storehouse. It was also observed that available micronutrients were within sufficiency level even after application of the mixture. Multi micronutrient mixture application at 7.5 kg ha-1 along with soil test based recommendation of NPK can be considered for future studies. [ABSTRACT FROM AUTHOR]

[Objective) The present study aimed to construct and develop rubber-based agroforestry systems for increasing total production and ecological benefit, thus ensuring the sustainable development of natural rubber cultivation in Hainan province. (Method) The research focused on the starch crops Maranta arundinacea L. (arrowroot), which were intercropped in immature conventional single-row rubber plantation (6-year old), immature (6-year old) and mature (20-year old) double-row rubber plantations. Its feasibility of intercropping in different rubber plantation was assessed based on its light condition, soil nutrient content, productivity, economical benefit and greenhouse gases emission. [Result] The light condition in the immature conventional single-row rubber plantation was the poorest. Yield of arrowroot inter-cropped in this rubber plantation was only 4750 kg/hm², while the yield of arrowroot intercropped in the immautre and mature double-row rubber plantations were 27 470 and 11 190 kg/hm², respectively, which light conditions were better (P<0.05). The variation of arrowroot biomass between different treatments was consistent with the yields. Totally, the nutritional ingredient (starch, crude protein and soluble sugar) did not differ significantly between treatments. The economical benefits of arrowroot intercropped in immature and mature double-row rubber plantation were 86 185 and 9285 Yuan/hm², respectively, while arrowroot intercropped in immature single-row rubber plantation was -21 415 Yuan/hm². In terms of net greenhouse gas emission, only the treatment intercropped in immature double-row rubber plantation was a sink with a potential of 368 kg/hm², while the other treatments were source of greenhouse gas emission. [Conclusion] The highest productivity and economical benefit are found in treatment of arrowroot intercropped in immature rubber plantation. Meanwhile, ecological benefit is also obtained. This type of rubber-based agroforestry system is suitable and recommended for popularization in Hainan province. [ABSTRACT FROM AUTHOR]

Drought, an intricate natural phenomenon globally, significantly influences the gross primary productivity (GPP) and carbon sink potential of tropical forests. Present research on the drought response primarily focuses on natural forests, such as the Amazon rainforest, with relatively limited studies on tropical plantations. Therefore, for a comprehensive understanding of global climate change, accurately evaluating and analyzing the sensitivity and vulnerability of rubber plantation GPP to various drought characteristics is crucial. The Standardized Precipitation Evapotranspiration Index (SPEI) was used in this research to quantify drought intensity. The Spatially Explicit Individual Based Dynamic Global Vegetation Model (SEIB-DGVM) was localized based on observation data from the Hainan Danzhou Tropical Agro-ecosystem National Observation and Research Station. Subsequently, the calibrated model was utilized to simulate the dynamic process of rubber plantation GPP under multi-gradient drought scenarios (2 extreme boundaries × 3 drought initiation seasons × 4 drought intensities × 12 drought durations × 12 SPEI time scales). The results show that the sensitivity and vulnerability of rubber plantation GPP exhibit significant differences under drought scenarios in different initiation seasons; GPP exhibits higher sensitivity to extreme, long-duration flash droughts in the early rainy season. Regarding vulnerability, the impact of extreme, long-duration flash droughts on GPP is most pronounced. This research lays the foundation for estimating the impact of droughts on the GPP of rubber plantations under future climate change scenarios, providing a scientific basis for enhancing regional ecological restoration and protection. [ABSTRACT FROM AUTHOR]

Agroforestry is known to significantly improve long-term land productivity, potentially enhancing the ability to cope with climate stress. However, there is limited information regarding the accurate monitoring of greenhouse gases (GHGs) in rubber-based agroforestry systems. Before GHGs can be accurately estimated, the diurnal variations and suitable sampling times must be studied to reduce the uncertainty of the manual static chamber method. In this study, the soil GHGs emitted from conventional single-row (SR) and improved double-row (DR) rubber plantations were compared across the dry and wet seasons in Hainan, China. A total of 1728 GHG samples from a field trial were collected, analyzed, and related to environmental factors. The results demonstrated that the diurnal fluxes of CO2 in rubber plantations were likely to remain fluctuating, with the maximum typically occurring during the night-time and daytime hours of the dry and wet seasons, respectively. A clearer double-peak (around 2:00 and 14:00) during the dry season and a daytime peak (14:00) during the wet season of the N2O were recorded. In addition to the commonalities, different seasons and different types of GHGs and rubber plantations also differed in their detailed fluctuation times and ranges; therefore, the determination of suitable sampling times should not ignore these factors in certain cases. Based on this study, it was determined that the late afternoon (16:00–18:00) was the suitable sampling time of soil GHGs in rubber plantations, instead of the most common morning times (with an underestimation of 25% on average). In addition, the air humidity during the dry season and the soil temperature during the wet season were both positively correlated with GHGs (p < 0.05). This study highlights the significance of accurately monitoring soil GHGs in rubber-based agroforestry systems, providing a basic reference for the development and management of climate-smart land use practices in rubber plantations. [ABSTRACT FROM AUTHOR]

The rapid, accurate, and non-destructive estimation of rubber plantation aboveground biomass (AGB) is essential for producers to forecast rubber yield and carbon storage. To enhance the estimation accuracy, an increasing number of remote sensing variables are incorporated into the development of multi-parameter models, which makes its practical application and the potential impact on predictive precision challenging due to the inclusion of non-essential or redundant variables. Therefore, this study systematically evaluated the performance of different parameter combinations derived from Sentinel-2 imagery, using variable optimization approaches with four machine learning algorithms (Random Forest Regression, RF; XGBoost Regression, XGBR; K Nearest Neighbor Regression, KNNR; and Support Vector Regression, SVR) for the estimation of the AGB of rubber plantations. The results indicate that RF achieved the best estimation accuracy ( R 2 = 0.86, RMSE = 15.77 Mg/ha) for predicting rubber plantation AGB when combined with Boruta-selected variables, outperforming other combinations (variable combinations obtained based on importance ranking, univariate combinations, and multivariate combinations). Our research findings suggest that the consideration of parameter-optimized remote sensing variables is advantageous for improving the estimation accuracy of forest biophysical parameters, when utilizing a large number of parameters for estimation. [ABSTRACT FROM AUTHOR]

Trees contribute to combating global warming by absorbing CO2, thus enhancing the quality of the environment. Sri Lanka maintains about 112,000 ha of Hevea brasiliensis (rubber) plantations, where 85.7% is in the wet zone. When rubber trees decline in latex production, after 30–33 years of planting, they are harvested to regenerate the next cycle. Rubber timber in Sri Lanka is used mainly for manufacturing interior parts of furniture, tool handles, and toys, leaving minimal chances for the emission of CO2 by combustion. Therefore, rubber is a good source of carbon sequestration, which can be used to earn additional benefits for the farmers. Estimating tree biomass helps to assess the carbon sequestration of those trees. Therefore this study aimed to build allometric models to predict the biomass using diameter at breast height (dbh) and total tree height (h). Since uprooting rubber trees is not allowed till maturity, whole‐tree, above‐ground, and stem biomass prediction models were built by uprooting ten 30‐ and 31‐year‐old trees from two rubber estates of the low country wet zone of Sri Lanka. For the rest of the ages, dbh and h prediction models were built by age using data collected from six age classes of rubber trees from the same two estates so those variables could be used as inputs to the biomass prediction models. For dbh and h models, Michaelis–Menten functions performed better than power‐law functions. Biomass was estimated for the stem and large branches by converting respective volumes to weights. Weight measurements were taken directly for biomass assessment for small branches, foliage, and roots. The quality of models was determined based on both qualitative and quantitative evaluations. The finding proved that the biomass of rubber plantations could effectively be estimated by dbh and h over time. [ABSTRACT FROM AUTHOR]

Understanding the dynamic relationships between soil organic carbon (SOC) and stand age are essential to quantify and predict the terrestrial carbon sequestration potential. However, the spatial patterns in the response of rubber plantation SOC to stand age and their driving factors remain unclear. Based on SOC and its components measurement at different soil depths (0–40 cm) in rubber plantations under five different age classes (0–5, 5–10, 10–20, 20–30, and >30 years) in three major rubber cultivation regions in China, distribution pattern and controlling factors of SOC were investigated. We found that SOC and its components showed significant spatial variability vertically with soil depth and laterally across sampling sites. SOC contents in three major rubber cultivation regions range from 4.48 to 20.13 g kg−1 at a depth of 0–40 cm. Among the sampling sites, Jinghong had the highest SOC content at a depth of 0–10 cm (20.13 g kg−1). On a large‐scale, the relationship between SOC and stand age in rubber plantations did not show a consistent pattern among different sampling sites. Additionally, annual rainfall, soil moisture content, and soil pH had a stronger impact on SOC in rubber plantations compared to stand age. The results indicated that the spatial variability of SOC in rubber plantations with stand age could be influenced by specific soil properties and climate‐related variables at each sampling site. This study emphasized the significance of conducting multi‐site, multi‐scale studies to enhance our understanding of SOC dynamics and its influencing factors, and help to more accurately predict the dynamic changes of soil carbon storage in rubber plantations. [ABSTRACT FROM AUTHOR]

Introduction: Clonal fragmentation helps to assess clonal plants' growth resilience to human and environmental disturbance. Although clonal integration in epiphytes in tropical rubber plantations is important to understand their role in enhancing biodiversity and ecosystem services, research on this subject is limited. These plantations are typically monospecific economic forests that face increased anthropogenic disturbances. Methods: In this study, we selected the clonal fern Pyrrosia nuda to study its survival status, biomass, maximum quantum yield of photosystem II (Fv/Fm), and frond length in response to the level of clonal fragmentation in a tropical rubber plantation. Results and discussion: The results showed that (1) clonal fragmentation significantly negatively affected the survival rate, biomass, and frond length of clonal plants, but with minimal effects on Fv/Fm at different growth stages; (2) the performance of a ramet (e.g., biomass or frond length) increased with ramet developmental ages and decreased with the number of ramets in a clonal fragment. The age-dependent impacts of clonal fragmentation provide insights into the biodiversity conservation of epiphytes and forest management in man- made plantations. Therefore, to better conserve the biodiversity in tropical forests, especially in environment-friendly rubber plantations, there is a need to reduce anthropogenic disturbances and alleviate the level of fragmentation. [ABSTRACT FROM AUTHOR]

Powdery mildew significantly impacts the yield of natural rubber by being one of the predominant diseases that affect rubber trees. Accurate, non-destructive recognition of powdery mildew in the early stage is essential for the cultivation management of rubber trees. The objective of this study is to establish a technique for the early detection of powdery mildew in rubber trees by combining spectral and physicochemical parameter features. At three field experiment sites and in the laboratory, a spectroradiometer and a hand-held optical leaf-clip meter were utilized, respectively, to measure the hyperspectral reflectance data (350–2500 nm) and physicochemical parameter data of both healthy and early-stage powdery-mildew-infected leaves. Initially, vegetation indices were extracted from hyperspectral reflectance data, and wavelet energy coefficients were obtained through continuous wavelet transform (CWT). Subsequently, significant vegetation indices (VIs) were selected using the ReliefF algorithm, and the optimal wavelengths (OWs) were chosen via competitive adaptive reweighted sampling. Principal component analysis was used for the dimensionality reduction of significant wavelet energy coefficients, resulting in wavelet features (WFs). To evaluate the detection capability of the aforementioned features, the three spectral features extracted above, along with their combinations with physicochemical parameter features (PFs) (VIs + PFs, OWs + PFs, WFs + PFs), were used to construct six classes of features. In turn, these features were input into support vector machine (SVM), random forest (RF), and logistic regression (LR), respectively, to build early detection models for powdery mildew in rubber trees. The results revealed that models based on WFs perform well, markedly outperforming those constructed using VIs and OWs as inputs. Moreover, models incorporating combined features surpass those relying on single features, with an overall accuracy (OA) improvement of over 1.9% and an increase in F1-Score of over 0.012. The model that combines WFs and PFs shows superior performance over all the other models, achieving OAs of 94.3%, 90.6%, and 93.4%, and F1-Scores of 0.952, 0.917, and 0.941 on SVM, RF, and LR, respectively. Compared to using WFs alone, the OAs improved by 1.9%, 2.8%, and 1.9%, and the F1-Scores increased by 0.017, 0.017, and 0.016, respectively. This study showcases the viability of early detection of powdery mildew in rubber trees. [ABSTRACT FROM AUTHOR]

• First report of RNA- seq analysis of Hevea clones in response to abnormal leaf fall (ALF) disease caused by Phytophthora. • A comparative transcriptome analysis of resistant and susceptible clone performed to gain insights into its resistance mechanism against ALF. • Compared to a susceptible clone, several differentially expressed genes were found in the resistant clone. • Several signalling pathways and transcription factors were also expressed during infection. Rubber is an important industrial commodity and Hevea brasiliensis is the commercial source of natural rubber (NR). Abnormal Leaf Fall (ALF) disease caused by Phytophthora meadii is one of the major diseases affecting yield of NR. Understanding Hevea-Phytophthora interaction mechanism is essential to manage this devastating disease. Transcriptome analysis was employed to gain an understanding on the molecular mechanisms that confer resistance to Phytophthora that would facilitate development of disease-tolerant Hevea clones. As our current understanding of Hevea-Phytophthora interaction is limited, an attempt was made to analyze and compare the transcriptomes of tolerant and susceptible clones of H. brasiliensis in response to P. meadii infection (in healthy and Phytophthora challenge-inoculated condition) during early, middle and late phases of infection by using the RNA-Seq technology. The transcriptome sequencing generated an average of 19,000 differentially expressed genes (DEGs) in both clones. When comparing the tolerant clone to the susceptible clone, there was an overall increase in the number of DEGs and a progression in the number of DEGs, indicating a more active engagement of transcriptional activity in the tolerant clone. Functional annotation, KEGG analysis and enrichment analysis revealed that the major pathways enriched for the DEGs were involved in plant hormone signal transduction and plant-pathogen interaction. An analysis of DEGs during each phase showed that the most active transcripts involved in defense mechanisms were activated during mid-phase and in the case of susceptible clone least transcripts were induced during mid-phase than in any other phase in both the clones. Many DEGs belonging to the MYB, NAC, WRKY and AP2/ERF transcription factor families were observed in both clones. Comparative studies revealed their differential involvement in tolerant and susceptible clones against Phytophthora infection. These findings may facilitate further exploration of Hevea-Phytophthora interaction and in cloning for defense related genes. [ABSTRACT FROM AUTHOR]

Corynespora leaf fall disease caused by the fungus Corynespora cassiicola is a major leaf disease of Hevea brasiliensis, the commercial source of natural rubber. Different clones of H. brasiliensis show varying levels of sensitivity towards different strains of C. cassiicola. The genetic mechanism behind the differential sensitivity of H. brasiliensis clones has to be identified in order to develop clones resistant to wider range of C. cassiicola strains. The available information on the sensitivity of H. brasiliensis clones is based on the observation of natural infection or infection of detached leaves. In the present study, the sensitivity of seven H. brasiliensis clones towards two strains of C. cassiicola belonging to two different races was determined using a more precise method by artificial infection of the plants under controlled conditions. Strain CLN 16 was found to be more virulent compared with CSB 16, as it induced more severe symptoms in a shorter period. Among the four different stages of leaves, Stage II leaves with copper brown to apple green colour showed higher sensitivity to both strains followed by Stage III leaves with apple green appearance. Among the clones, RRIM 600 had a higher susceptibility towards CSB 16; however, it was the most resistant clone towards CLN 16. Clone PB 350 showed the highest susceptibility towards CLN 16 whereas RRIM 928 showed the highest resistance towards CSB 16. The present study provides a platform for further studies leading to the development of H. brasiliensis clones with resistance towards wider range of C. cassiicola strains. [ABSTRACT FROM AUTHOR]

Background and aims: There is still limited knowledge regarding the dynamics of soil microbial community structures and functional groups during forest secondary succession after rubber monocultures (RP) abandonment. Methods: Bacterial and fungal communities and functions were investigated for the soil from six forest stands with three replicate plots. Selected stands included an RP, four spontaneous secondary forest stands that formed after RP abandonment at 1 (SF_1), 10 (SF_10), 20 (SF_20), and 40 (SF_40) years, as well as a primary forest (PF, approximately 100 years). Results: After RP abandonment, the alpha-diversity metrics of soil microbial communities increased during the first 40 years of succession but decreased in PF. The biomarkers Proteobacteria and Mortierellomycota increased significantly (P < 0.05) by 84% and 633% in PF, respectively, while Firmicutes showed a significant decrease of 89% in comparison with SF_1. Secondary succession increased the relative abundance of bacterial functional groups related to carbon cycling and fungal functional groups (especially ericoid mycorrhizal). Soil pH was the main edaphic factor in shaping microbial communities and functions. In addition, soil moisture and seasonal variations had direct impacts on fungal communities and bacterial functions. Conclusions: Collectively, these findings suggest that different successional trajectories occur in bacteria and fungi, owing to their divergent responses to the changes in season, soil moisture, and nutrients. Specifically, the frequent shifts in bacterial dominant phyla during succession, as well as the increased susceptibility of diversity and functional groups to season, indicate that bacteria respond more quickly to disturbances compared to fungi. [ABSTRACT FROM AUTHOR]

Aims: Termites function as "soil engineers" in tropical agroforestry ecosystems. However, of their role in phosphorus (P) cycling little is known. We aimed to investigate the impact of termite activity on soil aggregate stability and P fractions at the aggregate level in a tropical rubber plantation. Methods: Fungus-growing termite mounds (active and abandoned) involving both above- and belowground locations were studied in a 24-year-old rubber stand. The mass percentage and stability of aggregates, P fractions contents and other major chemical properties of soil aggregates were measured. Aggregate-associated P preservation capacity was also calculated. Results: More aggregates < 1 mm in size were concentrated in active aboveground mounds than active belowground chambers, thus resulting in weaker stability and erosion resistance, whereas the opposite trend occurred in abandoned mounds. The concentrations of labile P (in > 2 mm aggregate size), moderately labile P (0.25–1 mm), and non-labile P (0.053–1 mm) in active aboveground mounds were significantly higher than other types. The changes in specific P forms enriched TPi in aggregates > 2 mm and TPo in 0.053–1 mm size of active aboveground mounds relative to others, implying the importance of Po storage in microaggregates induced by termite activity involved in long-term P transformation. Furthermore, middle-sized (0.25–2 mm) aggregates stored more P and represented the highest P storing capacity, especially for active belowground chambers. Conclusions: These results suggest that in the presence of termite activity, P cycling is greatly enhanced in aboveground mounds despite the poor aggregate stability, whereas P forms are stable after mound abandonment, except for a higher H2O-Pi concentration aboveground. Our study provides an important reason why mound soils can be considered as fertility amendments for agroforestry practices in P-deficient tropical soils. [ABSTRACT FROM AUTHOR]

Enhanced rock weathering (ERW) has been proposed as a measure to enhance the carbon (C)‐sequestration potential and fertility of soils. The effects of this practice on the soil phosphorus (P) pools and the general mechanisms affecting microbial P cycling, as well as plant P uptake are not well understood. Here, the impact of ERW on soil P availability and microbial P cycling functional groups and root P‐acquisition traits were explored through a 2‐year wollastonite field addition experiment in a tropical rubber plantation. The results show that ERW significantly increased soil microbial carbon‐use efficiency and total P concentrations and indirectly increased soil P availability by enhancing organic P mobilization and mineralization of rhizosheath carboxylates and phosphatase, respectively. Also, ERW stimulated the activities of P‐solubilizing (gcd, ppa and ppx) and mineralizing enzymes (phoADN and phnAPHLFXIM), thus contributing to the inorganic P solubilization and organic P mineralization. Accompanying the increase in soil P availability, the P‐acquisition strategy of the rubber fine roots changed from do‐it‐yourself acquisition by roots to dependence on mycorrhizal collaboration and the release of root exudates. In addition, the direct effects of ERW on root P‐acquisition traits (such as root diameter, specific root length, and mycorrhizal colonization rate) may also be related to changes in the pattern of belowground carbon investments in plants. Our study provides a new insight that ERW increases carbon‐sequestration potential and P availability in tropical forests and profoundly affects belowground plant resource‐use strategies. [ABSTRACT FROM AUTHOR]

This research conducted between June 2016 and April 2018 employs ethnographic research, archival sources, and observations to reveal the emergence of the Plantationocene in Mozambique's Lugela district. It explores how historical exploitation and governance of land and people by colonial companies, specifically Société du Madal, have influenced the current plantation regime. By focusing on a MHL rubber plantation in the postcolonial era, the article exposes how the plantation revitalizes colonial methods of racist capital accumulation. The study highlights the detrimental effects of large-scale plantations on rural communities, including marginalization, dispossession, displacement, and the objectification of people and landscapes as mere commodities for capital accumulation. Additionally, it emphasizes how these projects impose new labour relations, racialized identities, and geographies, perpetuating the remnants of colonialism while endorsing a neoliberal framework that further deepens existing inequalities. [ABSTRACT FROM AUTHOR]

Hevea brasiliensis (Para rubber tree) is a commercially cultivated crop for latex production worldwide. Rubber trees from Southern states of India have been affected by Circular Leaf Spot (CLS) disease caused by Colletotrichum fructicola and Colletotrichum siamense causing yellowing and severe defoliation in rubber plantations in recent years. In this study, we collected infected leaf samples of CLS disease from different locations in the South Indian states of Kerala, Tamil Nadu, and Karnataka. Colletotrichum fructicola and C. siamense were identified as the causative agents of CLS disease and the isolate, C. fructicola was used for genomics analysis. We performed whole-genome sequencing (WGS) of, C. fructicola and carried out gene content analysis by comparing it with other reported Colletotrichum species. In silico analysis revealed a rich repertoire of pathogenicity genes and CAZymes in C. fructicola encoding secreted proteins, effectors, plant cell wall degrading enzymes, and secondary metabolism-associated proteins with possible roles in the host-specific interaction and pathogenicity. Our dataset provides a rich resource for understanding the pathogenicity-related genes that are involved in CLS disease progression and gives a basis for subsequent functional genomics research in C. fructicola. [ABSTRACT FROM AUTHOR]

Conventional fertilization practices can lead to many ecological problems, such as nutrient imbalance, soil acidity, and reduced soil fertility, in natural rubber plantations. To address these challenges, a field investigation was strategically carried out to substitute inorganic fertilizer with organic fertilizer, consisting of six treatments: no fertilization (CK), inorganic fertilizer (NPK), 25% replacement of inorganic through organic (25% manure (M)), 50% replacement of inorganic through organic (50% manure (M)), 75% replacement of inorganic through organic (75% manure (M)), and 100% organic fertilizer (100% manure). The soil physicochemical properties (soil organic carbon (SOC), total nitrogen (TN), mineral nitrogen (N), ammonium nitrogen (NH4+-N), and nitrate nitrogen (NO3−-N)), C:N, pH, and the carbon- and nitrogen-converting enzymes β-1,4-glucosidase (BG), N-acetylglucosaminidase (NAG) and L-leucine aminopeptidase (LAP) were all determined. The partial substitution of inorganic fertilizer with organic fertilizer (i.e., 75% M at surface soil layer) showed higher SOC (14.52 g·kg−1), TN (1.06 g·kg−1), N (20.07 mg·kg−1), C:N (14.63), NH4+-N (10.63 mg·kg−1), and NO3−-N (11.06 mg·kg−1) than NPK and CK. This increase in physicochemical properties after partial replacement of inorganic with organic fertilizer resulted from higher carbon and nitrogen enzyme activities (BG (143.17·nmol·g−1·h−1), NAG (153.96 nmol·g−1·h−1), and LAP (153.48 nmol·g−1·h−1)) compared to NPK and CK. Further, the Pearson correlation and redundancy analysis (RDA) analyses confirmed a significant positive correlation between SOC, N, and soil enzymes. This study presents a new strategy for assessing the impact of partially replacing inorganic fertilizer with organic fertilizer in rubber plantations in tropical regions, mainly by modifying the soil nutrient composition. [ABSTRACT FROM AUTHOR]

Agroforestry combines trees and crops for sustainable benefits. We explore rubber and canna integration into agroforestry, emphasizing sustainability, biodiversity, and carbon sequestration. This study assesses C. indica's viability beneath 7-8-year-old rubber plantations, examining its impact on soil, microbial communities, and latex production. The research site in Subang, Indonesia, features, at the beginning, six-year-old rubber trees with variations in sunlight under canopies. Wild C. indica rhizomes from Mid Java are planted beneath rubber trees and open ground. No significant difference was found in plant height, rhizome weight, leaf area, number of leaves, r/s ratio, SLA, LWR, and LAR between C. indica cultivated beneath rubber trees (RC agroforestry) and on open ground. Although not significant, RC soil had higher N, P, K, and organic C levels than rubber monoculture (RM) soil two years after adopting the rubber-canna agroforestry system. After six years, RC soil had a greater pH, C, N, P, and K, clay and silt content, and Shannon E index than RM soil. Analysis of soil metagenomics showed the phylum Proteobacteria dominates and enhances soil fertility, particularly in RC soils. These results increase latex output at the RC site over the RM location. In conclusion, the Rubber-Canna agroforestry system enhances sustainability, soil fertility, and crop yield, addressing food security and environmental concerns. The primary novelty of this six-year study lies in the integration of C. indica into Southeast Asia's rubber agroforestry systems, highlighting its unique characteristics such as low-light survival, which can contribute to food security and soil protection. [ABSTRACT FROM AUTHOR]

Rubber plantations have increased significantly under unprecedented economic growth in tropical areas, which leads to soil degradation and thereby alters soil hydrological processes. However, our understanding of how forest conversion affects soil hydrological processes remains unclear. Here, we collected soil samples from secondary forests (SF) and rubber plantations (RP) to determine the soil hydrological characteristics. We found the topsoil (0–20 cm) water retention in SF was higher than that of RP but displayed the contrast pattern in a deeper soil layer (20–60 cm). Meanwhile, the soil infiltration rates among the two vegetation types decreased significantly with infiltration time, with higher stable soil infiltration rates in SF than those in RP. Moreover, soil properties were also impacted by the forest conversion, such as the topsoil capillary porosity (CP) and total porosity (TP) in SF were higher than those of RP but contrasted in a deep soil layer. In comparison, the topsoil bulk density (BD) in SF was lower than that of RP, but contrasted in the deep soil layer and reached a significant level in the 0–10 and 40–50 cm (P  < 0.05). Overall, the soil water retention was mainly determined by the CP, which could explain 31.56% of the total variance in soil water retention, followed by TP (26.57%) and soil BD (26.47%), whereas soil texture exerts a weak effect on soil water retention. Therefore, we can conclude that the conversion of tropical rainforest into rubber plantations may accelerate soil erosion owing to its lower topsoil water retention and soil infiltration rates. [ABSTRACT FROM AUTHOR]

Meteorological conditions play a crucial role in driving outbreaks of rubber tree powdery mildew (RTPM). As the climate warms and techniques improve, rubber cultivation is expanding to higher latitudes, and the changing climate increases the RTPM risk. Rubber plantations on Hainan Island, situated on the northern margin of the tropics, have been selected as a case study to explore the meteorological mechanisms behind RTPM outbreaks quantitatively using a structural equation model, and project current and future RTPM outbreak patterns under different climate change scenarios by building predictive models based on data-driven algorithms. The following results were obtained: (1) days with an average temperature above 20 °C and days with light rain were identified as key meteorological drivers of RTPM using structural equation modeling (R2 = 0.63); (2) the Bayesian-optimized least-squares boosted trees ensemble model accurately predicted the interannual variability in the historical RTPM disease index (R2 = 0.79); (3) currently, due to the increased area of rubber plantations in the central region of Hainan, there is a higher risk of RTPM; and (4) under future climate scenarios, RTPM shows a decreasing trend (at a moderate level), with oscillating and sporadic outbreaks primarily observed in the central and northwest regions. We attribute this to the projected warming and drying trends that are unfavorable for RTPM. Our study is expected to enhance the understanding of the impact of climate change on RTPM, provide a prediction tool, and underscore the significance of the climate-aware production and management of rubber. [ABSTRACT FROM AUTHOR]

The hydrological function of peatlands, one of which is acting as a medium for storing and releasing water, undergoes alteration due to degradation. Saturated hydraulic conductivity (Ks) is a pivotal parameter for comprehending the hydraulic properties of peatlands. Ks plays a crucial role in the transmission and release of water influenced by other peat properties. This research examined the impact of Ks and selected peat properties, namely bulk density and available water content, to depict the hydrological function in rewetted peatlands. The study sites are rubber plantation (RB), oil palm plantation (OP), and drained secondary forest (SF). Results revealed a significantly higher Ks in OP (106.7 cm hr-1) compared to RB (19.56 cm hr-1) and DSF (15.1 cm hr-1). The hydrological function at all study sites was categorized as high, with minor degradation in OP and moderate degradation in RB and SF. Nonetheless, these findings necessitate fundamental interpretation and adjustment. The outcomes of this study can be utilized to prioritize rewetting efforts in the study sites, emphasizing the importance of prioritizing immature peat (fibric) with high Ks. [ABSTRACT FROM AUTHOR]

Accurate canopy height mapping is crucial for estimating rubber plantation productivity, carbon storage, and biomass accurately. The prevailing method combines Global Ecosystem Dynamics Investigation (GEDI) data with spatially continuous variables. However, these models often overlook forest growth variables and face challenges with GEDI geolocation errors. This study introduces a novel GEDI filtering technique to screen for high-quality footprints and incorporates rubber plantation age as a key factor. Utilizing a comprehensive dataset from Landsat-8, Sentinel-2, and Phased Array type L-band Synthetic Aperture Radar (PALSAR-2), we established a model for the canopy height of rubber plantations. Our multifaceted approach yields significant improvements: 1) enhanced rubber canopy height estimation accuracy, evidenced by an R-squared value of 0.86 and reduced error metrics (RMSE = 1.68, MAE = 1.32); 2) The mean difference of −2.81 ± 3.05 m compared with Potapov’s study and −5.62 ± 6.64 m compared with Liu’s, indicating superior consistency and reduced underestimation; and 3) Accurately average canopy heights for rubber plantations aged between 3 and 30 years on Hainan Island at 15.67 ± 1.87 m, spanning a height range of 5.02 to 18.59 m. The integration of stand age and the GEDI footprint filtering technique markedly enhances canopy height estimation accuracy, offering valuable insights for ecological monitoring and the advancement of sustainable forest management practices.

The article "Scales and scaling in Tree Physiology" explores the concept of scaling in tree physiology research. Scaling involves studying processes and phenomena at different levels, from molecular to whole-plant studies. The article provides examples of downscaling, such as examining gene expression and physiological responses to stress, and upscaling, such as mathematical modeling of gas transport and analyzing tree-ring data. The article highlights the need for researchers to consider scaling in their studies to gain a comprehensive understanding of tree physiology. It also discusses specific studies that use a mechanistic approach to understand processes and their consequences at higher scales. Overall, the article emphasizes the importance of identifying relevant scales of study and conducting scaling of mechanisms and processes in tree physiology research. [Extracted from the article]

Mechanical damage and bruising of fruit is a critical problem in the food industry. Minimizing brusing and damage can be achieved by designing energy-absorbing structures and packaging systems in order to ensure the long-term quality of fresh produce. The aim of this study is to investigate the response and bruise susceptibility of pears under impact loading conditions through finite element analysis (FEA) methods. In this paper, three impact heights (0.25 m, 0.5 m, and 1.0 m), four impact material surfaces (poplar wood, rubber, cardboard, and acrylonitrile butadiene styrene (ABS) plastic), two packaging sizes (standard 0.22″ and sandwich lattice 2.1″), and three impact design structures (rigid, corrugated, and honeycomb) are considered. Based on mesh sensitivity analysis, a mesh element of 1.5 mm was adopted for all simulations, assuring the accuracy of results and considering the trade-off between mesh size and computational time. The response surface analysis approach was utilized in order to develop predictive empirical models related to pear bruising. Results revealed that the rubber-based impact platform yielded minimal bruise susceptibility at all heights, while standard-sized corrugated cardboard performed best at a height of 0.25 m. Furthermore, single, double, and triple layers of packaging cardboard were tested. We observed that adding a second soft layer of corrugated cardboard reduced the stress on the pear by around 33%. However, adding a third layer only reduced stress by 5%. The 3D-printed honeycomb ABS has potential as protective packaging but would require further investigations and parameter optimization. Stacking multiple layers of cardboard on top of each other is a cost-effective solution that could improve damping and, therefore, ensure good quality and increase the shelf life of the fresh produce. This study will help decision-makers select the optimal energy-absorbing material for cushioning and packaging designs in order to improve the handling and post-harvesting logistics of fresh produce. [ABSTRACT FROM AUTHOR]

Melastoma malabathricum L. (Melastomataceae) is a widely distributed tropical shrub that grows in Southeast Asia. Recent research found that M. malabathricum has a bioremediatory potential that can accumulate high concentrations of toxic metals such as Al, Pb, As, and Cr. Thus, this study aimed to investigate the metal hyperaccumulation in M. malabathricum from various populations and their relation to soil edaphic factors. We collected mature leaves and soils of M. malabathricum from 15 different populations in Negeri Sembilan, Selangor, and Pahang in Peninsular Malaysia. These 15 populations consist of lowland forests, dump sites, riparian, oil palm and rubber plantations, paddy fields, and mining sites. We found that M. malabathricum accumulated high concentrations of Al (3.45±1.58 to 8.697±1.61 mg g-1) followed by Fe (1.02±0.02 to 1.07±0.04 mg g-1), Pb (0.013±0.001 to 0.016±0.001 mg g-1), As (0.008±0.005 to 0.23±0.004 mg g-1), and Cr (0.005±0.0003 to 0.02±0.01 mg g-1). The highest concentration of soil Al was 85.95±5.00 mg g-1, Fe with 69.960±7.47mg g-1, Pb with 0.192±0.03 mg g-1, As with 0.156±0.06 mg g-1 and Cr with 0.133±0.03 mg g-1. We found no significant association between high foliar metal concentrations of the metals (Al, Pb, As & Cr) with the soil chemical properties but some soil metal elements were intercorrelated with foliar metal concentrations. Understanding the potential of M. malabathricum in accumulating high levels of metal elements, provides useful information for phytoremediation works. Further research is required to investigate the mechanism uptake and tolerance of heavy metals in M. malabathricum. [ABSTRACT FROM AUTHOR]

This study aims to get an insight into the major sectors with a green job potential in Delta State and to further analyze the argument that job creation is one of the important benefits of green growth policies - that is, policies to foster economic growth and development while ensuring that natural assets continue to provide the resources and environmental services on which our well-being relies (Bowen and Kuralbayeva, 2015). The claims that the greening of economies is a net generator of decent jobs - good jobs that offer adequate wages, safe working conditions, job security, reasonable career prospects and worker rights (UNEP (2011). There is a great need to promote and create lots of green jobs to make Delta State a better place for future generations. The potential areas of green jobs in Delta State has revealed by the studies include among others: Rubber plantations, cassava (manioc), fish, palm oil and kernels, yams, and plantains, flour-milling plant, sawmilling, solar, wind, geothermal, biomass and water, tourism, building sectors, forestry activities, waste management, railways, health sector, government bodies, education sector, Escravos Gas-to-Liquids (EGTL) plant, an integrated steel plant in Aladja, small enterprises and the market within SMEs. The study recommends that for green jobs to thrive in Delta State, there needs to be an increased appreciation for green and sustainable practices; Individualistic efforts from different agents, like governmental agencies, private sector, policymakers, employers, and employees are very important towards the creation of a Green Economy; better integration of employment needs and research programs; and a specific regulatory framework to promote green businesses, and a competitive ecosystem that creates green jobs. [ABSTRACT FROM AUTHOR]

Soils in rubber plantations have unique characteristics due to their prolonged and excessive uses. These practices have changed soil qualities, production, and the geographical distribution of soil conditions. For this reason, research on the spatial analysis of soil attributes in rubber plantations is essential. Although it is acknowledged that there are proven methods for accounting for geographical variability, their use in rubber plantations is still somewhat restricted. Evidence also demonstrates ongoing debate and variation in the findings on the capacity of methods to predict spatial variability. Therefore, the primary goal of this study is to examine how well various approaches perform when using ordinary kriging to analyze spatial variability of three soil properties: Soil Available Potassium (SAP), pH, and Electrical Conductivity. The methodology employed in this work includes (a) grid sampling for data collection, (b) interpolation using Ordinary kriging with three methods (exponential, spherical, and Gaussian), (c) mapping, and (d) evaluation. The findings of this study demonstrate that semi-variogram analysis using three distinct methods yields somewhat varied outcomes with accuracy in higher order from SAP, soil EC, and soil pH. The results of this study also show that the different methods have unique characteristics when representing spatial structure. These findings suggested that the number of samples and the selection of interpolation techniques are essential factors in studying these three soil properties and determining the accuracy of the results. [ABSTRACT FROM AUTHOR]

Background: Studying green manure decomposition in various returning methods can establish a scientific foundation for farmland nutrient management. Methods: In a rubber plantation on Hainan Island, China, utilized the nylon mesh bag method to imitate the decomposition of kudzu (whole plant, stem, and leaf) under two returning methods (mulching and burying) in two different sites (young and mature rubber plantations). The study examined the decomposition rate and nutrient release dynamics of kudzu, as well as the effects of kudzu reintroduction on several soil properties including soil pH, soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), nitrate nitrogen (NO3−-N), ammonium nitrogen (NH4+-N), available phosphorus (AP), and enzyme activities. Results: Compared with mulching, the burying returning method significantly increased the kudzu decomposition rate and nutrient release proportions. After 270 days, more than 80% of the C, N, and P in different components of kudzu were released. The decomposition rate was found to be more affected by the initial soil factors than by the endogenous nutrients of kudzu. Compared with CK, all kudzu treatments led to significant increases in soil enzyme activities and soil pH, SOC, NO3−-N, and AP concentrations in two rubber plantations. The TN and NH4+-N concentrations were significantly increased in mature rubber plantations, while the TP was the opposite. Conclusion: The kudzu returned can effectively alleviate soil acidic, improve soil nutrient availability, regulating soil enzyme activities of the rubber plantation in the short-term. These results provide a scientific basis for the rational application of kudzu in rubber plantations. [ABSTRACT FROM AUTHOR]

Pestalotiopsis leaf fall disease (PLFD) has emerged as a significant and detrimental foliar disease affecting Hevea brasiliensis in Malaysia since 2017. The disease poses a severe threat to rubber plantations, leading to economic losses and impacting the country's rubber industry. Understanding the factors contributing to lesion incidence and the potential presence of a fungal complex is crucial for effective disease management. This study aimed to address key objectives, including the identification of primary fungal pathogens responsible for lesion development and examination of the role of co-infections in lesion incidence. To achieve these objectives, five fungal isolates (Neopestalotiopsis surinamensis, Colletotrichum conoides, Lasiodiplodia theobromae, Phyllosticta fallopiae and Letendraea cordylinicola) previously identified through the Internal Transcribe Spacer (ITS) regions were subjected to in vitro artificial inoculation experiments on detached rubber leaves. Various combinations of these fungal isolates were tested to evaluate their interactions as possible causal pathogens of PLFD. Three variables were assessed, viz. type of water source (sterile distilled water and rainwater), presence of leaf wounds, and inoculation techniques (conidial suspensions and mycelial agar plugs). Lesion incidence was evaluated based on sporulating occurrences on the detached leaves, recorded seven days after inoculation. Statistical analysis, including non-parametric Pearson's chi-square tests revealed that the fungal isolates Lasiodiplodia theobromae, Colletotrichum conoides and Neopestalotiopsis surinamensis were the primary contributors to lesion incidence, accounting for 83%, 69%, and 57% of cases, respectively. The study also revealed that lesion incidence was not significantly influenced by inoculation techniques or type of water source but was greater in wounded leaves compared to unwounded leaves. Co-inoculation experiments demonstrated increased lesion incidence, highlighting the role of co-infections in disease severity. Importantly, this study elucidated a potential fungal complex associated with PLFD and provided insights into its epidemiology. The findings contribute to deeper understanding of the disease, offering valuable guidance for effective disease management strategies in H. brasiliensis cultivation in Malaysia. [ABSTRACT FROM AUTHOR]

Rubber (Hevea brasiliensis) is a priority tree crop that produces natural rubber (NR), making it an important plantation commodity in the Philippines. However, NR production is confronted with major constraints, including rubber diseases resulting in low latex yield. Twenty-five rubber farms located in five major rubber-producing municipalities (Kidapawan, Antipas, Makilala, Matalam and President Roxas) of Cotabato, Philippines, were surveyed for prevalence of major rubber leaf diseases. Information on farm practices and environmental variables was collected. The majority of rubber farmers were smallholders with hectarage planted ranging between 1 and 15 hectares. The most planted clones are RRIM 600 and PB 260, which are high-yielding yet susceptible to many foliar pathogens. Six leaf diseases, viz. Oidium powdery mildew, Colletotrichum leaf disease, Corynespora leaf fall/spot, Phytophthora leaf blight, bird's eye spot and algal spot, were documented in this study. Powdery mildew was the most prevalent in Cotabato with the highest percentage and severity of infections in all plantations, followed by Colletotrichum leaf disease. Information on disease prevalence in surveyed areas is important for disease management actions. [ABSTRACT FROM AUTHOR]

【Objective】In order to provide scientific basis for the optimization of intercropping patterns and the management of intercropping under rubber plantations in the future, the effects of different intercropping patterns on the functional diversity of soil microbial communities in mature rubber plantations were studied. 【Method】Biolog-ECO technology was used to study the characteristics of soil microbial functional diversity, and the differences of soil microbial metabolic activity and diversity on carbon sources in different intercropping plantations were analyzed. 【Result】Soil microbial carbon utilization was stable at 216 hours, and the average light absorption value AWCD of different treatments was in the order of rubber-kinggrass intercropping＞rubber-coffee intercropping＞rubber-puzzle intercropping＞rubber.The intercropping pattern not only increased the types of carbon sources utilized by soil microorganisms, but also enhanced the metabolic activity of carbon sources.The metabolic capacity of soil microorganisms to carbohydrates, amino acids, phenolic acids, carboxylic acids and polymers was the strongest in rubber-kinggrass intercropping, and the metabolic capacity of amines was the strongest in rubber-coffee intercropping.There were significant differences in soil microbial carbon source utilization between intercropping patterns and rubber plantation by PCA （principal component analysis), significant differences between rubber-kinggrass and rubber-coffee, rubber-puzzle, but no significant differences between rubber-coffee and rubber-puzzle intercropping.The research showed that different intercropping modes could improve the soil microbial diversity index, and there were significant differences in AWCD value and McIntosh index among different treatments, but no significant differences in Shannon index and Simpson index.Correlation analysis showed that the metabolic function of soil microbial carbon source was closely related to soil environmental factors, and soil water content, pH and organic matter were the main factors affecting the differences of soil carbon source metabolism. 【Conclusion】Intercropping for kinggrass, puzzle and coffee can improve soil ecological environment, promote the utilization of soil carbon sources, and enhance the functional diversity of soil microbial community in rubber plantation. [ABSTRACT FROM AUTHOR]

The rubber elongation factor (REF) is the most abundant protein in the latex of Hevea brasiliensis, which is closely related to natural rubber biosynthesis. In order to gain a deeper understanding of the transcriptional regulation mechanism of HbREF1, a 1758 bp genomic DNA fragment of the HbREF1 promoter was isolated. Promoter sequence analysis revealed several transcription factor binding sites in the HbREF1 promoter, such as bZIP, bHLH, EIL, AP2/ERF, MYB, and Trihelix. To assess the promoter activity, a series of HbREF1 promoter deletion derivatives were created and fused with firefly luciferase (LUC). The LUC image demonstrated that all of the HbREF1 promoters exhibited transcriptional activity. Furthermore, the assay revealed the presence of multiple regulatory elements within the promoter region that negatively regulate the transcriptional activity. Subsequent analysis of the transcriptional activity following treatment with phytohormones identified an ABA-responsive element located between −583 bp and −200 bp, an ET-responsive element between −718 bp and −583 bp, a JA-responsive element between −1758 bp and −1300 bp, and a SA-responsive element between −1300 bp and −718 bp. These results were largely consistent with the predictions of cis-acting elements. This study has established significant groundwork for future investigations into the regulatory mechanism of HbREF1. [ABSTRACT FROM AUTHOR]

The plantation’s sub-contribution sector to the country’s gross domestic product reflects the role oil palm plantations have played in boosting the economy. The goal of this study is to examine land efficiency and the variables that affect its value in Indonesian national superior plantations, by the application of the Stochastic Frontier Analysis (SFA) method. Age, education, financial situation, and geographic location of the farmer all affect their engagement in agriculture, particularly when it comes to spreading new techniques. Therefore, policies that are based on input variables that demonstrate substantial outcomes in boosting the output of rubber plantations in Indonesia must be implemented by the government through certain institutions. [ABSTRACT FROM AUTHOR]