Rainforest Research Articles

No Field Evidence of Grass Fuel Structure effects on Postfire Tree Mortality in Juniperus virginiana

Prescribed fires are an important management tool for containing woody plant encroachment in rangeland ecosystems. Grasses are the dominant fuel type in rangelands. Past work has shown that grass canopy architecture, which varies among grass species, can influence flammability. Whether variation in grass fuel structure can influence postfire plant responses has not yet been tested. To bridge this gap, we set up field burning experiments with different fuel treatments and examined postfire mortality of Juniperus virginiana L. in a tallgrass prairie in southwestern Missouri. We sampled 60 trees and measured tree height and diameter at breast height before the fire. Fuels surrounding each tree were manipulated to vary independently in both fuel load and fuel structure. Flame temperatures were measured during the fire, and both stem and canopy injuries were evaluated 1 d after the fire. We surveyed tree mortality 7 mo after the fire. We found no effects of either fuel load or fuel structure on postfire mortality or on canopy injury in J. virginiana. Canopy injury was a critical fire severity measurement determining postfire mortality in J. virginiana, and taller trees are more fire resilient. Despite laboratory-observed fuel structure effects on flammability, this study finds no evidence for the importance of grass fuel load and canopy architecture in influencing postfire tree response. This result might arise from the low crown depth and low canopy water content of J. virginiana, which can promote canopy fire and result in a high mortality rate across fuel treatments. Notwithstanding the negative results, testing laboratory-based findings in field settings is important for further examining laboratory observations and upscaling individual-level processes to ecosystems to help identify the key ecological processes determining population dynamics and community assembly. Our study also suggests that prescribed fire is an effective tool to remove encroaching J. virginiana in tallgrass prairies at an early stage.

Combining spaceborne lidar from the Global Ecosystem Dynamics Investigation with local knowledge for monitoring fragmented tropical landscapes: A case study in the forest-agriculture interface of Ucayali, Peru.

Improving our ability to monitor fragmented tropical ecosystems is a critical step in supporting the stewardship of these complex landscapes. We investigated the structural characteristics of vegetation classes in Ucayali, Peru, employing a co-production approach. The vegetation classes included three agricultural classes (mature oil palm, monocrop cacao, and agroforestry cacao plantations) and three forest regeneration classes (mature lowland forest, secondary lowland forest, and young lowland vegetation regrowth). We combined local knowledge with spaceborne lidar from NASA's Global Ecosystem Dynamics Investigation mission to classify vegetation and characterize the horizontal and vertical structure of each vegetation class. Mature lowland forest had consistently higher mean canopy height and lower canopy height variance than secondary lowland forest (μ = 29.40 m, sd = 6.89 m vs. μ = 20.82 m, sd = 9.15 m, respectively). The lower variance of mature forest could be attributed to the range of forest development ages in the secondary forest patches. However, secondary forests exhibited a similar vertical profile to mature forests, with each cumulative energy percentile increasing at similar rates. We also observed similar mean and standard deviations in relative height ratios (RH50/RH95) for mature forest, secondary forest, and oil palm even when removing the negative values from the relative height ratios and interpolating from above-ground returns only (mean RH50/RH95 of 0.58, 0.54, and 0.53 for mature forest, secondary forest, and oil palm, respectively) (p < .0001). This pattern differed from our original expectations based on local knowledge and existing tropical forest succession studies, pointing to opportunities for future work. Our findings suggest that lidar-based relative height metrics can complement local information and other remote sensing approaches that rely on optical imagery, which are limited by extensive cloud cover in the tropics. We show that characterizing ecosystem structure with a co-production approach can support addressing both the technical and social challenges of monitoring and managing fragmented tropical landscapes.

Actividad repelente e insecticida de cuatro aceites esenciales de plantas recolectadas en Chocó-Colombia contra Tribolium castaneum

This study aimed to determine the repellent and insecticidal activity of four essential oils (EOs) from plants collected in the Chocó rain forest, Colombia, against T. castaneum. Conventional hydrodistillation was used to obtain the EOs. The repellent and insecticidal activities were evaluated by the preference area and gas dispersion methods, respectively. Statistical differences (p&lt;0.05) were determined by applying a student’s t-test. EOs of Siparuna guianensis, S. conica, Piper marginatum, and Nectandra acutifoliashowed excellent repellent properties as the main findings, highlighting S. conicaEO with 84% repellency (1μL/cm2), while P. marginatumshowed to be bioactive to the dose of 500 μL/mL (72 h), inducing mortality of 100% of the exposed population. In conclusion, the results evidenced the repellent properties of the EOs evaluated against T. castaneum, which allows us to conclude that these plant species are potential natural sources producing bio-repellents that contribute to the integrated control of T. castaneum.

INTEGRATED PEST MANAGEMENT AND ENTOMOPATHOGENIC FUNGAL BIOTECHNOLOGY IN THE LATIN AMERICAS: I-OPPORTUNITIES IN A GLOBALAGRICULTURE

Entomopathogenic fungi (EPF) have been used as insect biocontrol agents separately and in integrated pest management (1PM) worldwide including in the Latin Americas. The proper use of these agents along with other elements and concepts of 1PM has significant impact on the provision of crops. fruits and other agricultura! products Entomopathogenic fungi can play a significant role in the preservation of the natural delicate balance of beneficia! biota and their active spreading from the surrounding natural habitats, such as the tropical rain forest, the humid cloudy forest in the Andes and other important ecosystems, to the agricultura} lands in Central and South America. Of ali known EPF, there are only about half a dozen for which prerequisite aspects of fungal biotechnology for industrial R and D are in place. Because of its precedent setting leadership in the use ofEPF in 1PM and agroecological practices, LatinAmerica stands to gain irnrnensely here and more so if the concept of rational design of bioinsecticides (RADBIO) is employed. The future prospects will depend on a balance of discovery research coupled to a strong and dependable industrialization effort to develop the framework for illustrating public acceptance, commercialization potential and widespread use of EPF in 1PM. The potential for the next generation of mycoinsecticides is now loorning on the horizon.

Anthropogenic restoration exhibits more complex and stable microbial co-occurrence patterns than natural restoration in rubber plantations

Forest restoration is an effective method for restoring degraded soil ecosystems (e.g., converting primary tropical forests into rubber monoculture plantations; RM). The effects of forest restoration on microbial community diversity and composition have been extensively studied. However, how rubber plantation-based forest restoration reshapes soil microbial communities, networks, and inner assembly mechanisms remains unclear. Here, we explored the effects of jungle rubber mixed (JRM; secondary succession and natural restoration of RM) plantation and introduction of rainforest species (AR; anthropogenic restoration established by mimicking the understory and overstory tree species of native rainforests) to RM stands on soil physico-chemical properties and microbial communities. We found that converting tropical rainforest (RF) to RM decreased soil fertility and simplified microbial composition and co-occurrence patterns, whereas the conversion of RM to JRM and AR exhibited opposite results. These changes were significantly correlated with pH, soil moisture content (SMC), and soil nutrients, suggesting that vegetation restoration can provide a favorable soil microenvironment that promotes the development of soil microorganisms. The complexity and stability of the bacterial-fungal cross-kingdom, bacterial, and fungal networks increased with JRM and AR. Bacterial community assembly was primarily governed by stochastic (78.79 %) and deterministic (59.09 %) processes in JRM and AR, respectively, whereas stochastic processes (limited dispersion) predominantly shaped fungal assembly across all forest stands. AR has more significant benefits than JRM, such as a relatively slower and natural vegetation succession with more nutritive soil conditions, microbial diversity, and complex and stable microbial networks. These results highlight the importance of sustainable forest management to restore soil biodiversity and ecosystem functions after extensive soil degradation and suggest that anthropogenic restoration can more effectively improve soil quality and microbial communities than natural restoration in degraded rubber plantations.

Ants may buffer the Janzen-Connell effect in a tropical forest in Southwest China.

Mutualistic symbioses between ants and plants are widespread in nature. Ants can deter unwanted pests and provide protection for plants in return for food or housing rewards. Using a long-term demographic dataset in a tropical seasonal rain forest in Southwest China, we found that associations with ants positively influenced seedling survival and adult growth, and also, species with extrafloral nectaries experienced weaker conspecific negative density dependence compared with species without extrafloral nectaries. Furthermore, we found strong evidence suggesting that species in our forest experienced conspecific density dependence, which we interpreted as heavy pest pressure that may drive the development of anti-pest symbioses such as the plant-ant relationship. Our findings suggest that ants and conspecific neighbors play important but inverse roles on plant survival and growth and that ants can buffer tree neighborhood interactions in this tropical forest.

Tracking shifts in forest structural complexity through space and time in human‐modified tropical landscapes

Habitat structural complexity is an emergent property of ecosystems that directly shapes their biodiversity, functioning and resilience to disturbance. Yet despite its importance, we continue to lack consensus on how best to define structural complexity, nor do we have a generalised approach to measure habitat complexity across ecosystems. To bridge this gap, here we adapt a geometric framework developed to quantify the surface complexity of coral reefs and apply it to the canopies of tropical rainforests. Using high‐resolution, repeat‐acquisition airborne laser scanning data collected over 450 km2 of human‐modified tropical landscapes in Borneo, we generated 3D canopy height models of forests at varying stages of recovery from logging. We then tested whether the geometric framework of habitat complexity – which characterises 3D surfaces according to their height range, rugosity and fractal dimension – was able to detect how both human and natural disturbances drive variation in canopy structure through space and time across these landscapes. We found that together, these three metrics of surface complexity captured major differences in canopy 3D structure between highly degraded, selectively logged and old‐growth forests. Moreover, the three metrics were able to track distinct temporal patterns of structural recovery following logging and wind disturbance. However, in the process we also uncovered several important conceptual and methodological limitations with the geometric framework of habitat complexity. We found that fractal dimension was highly sensitive to small variations in data inputs and was ecologically counteractive (e.g. higher fractal dimension in oil palm plantations than old‐growth forests), while rugosity and height range were tightly correlated (r = 0.75) due to their strong dependency on maximum tree height. Our results suggest that forest structural complexity cannot be summarised using these three descriptors alone, as they overlook key features of canopy vertical and horizontal structure that arise from the way trees fill 3D space.Keywords: Forest disturbance, LiDAR, logging, recovery, remote sensing, structural complexity

Influence of Mining on Nutrient Cycling in the Tropical Rain Forests of the Colombian Pacific

Nutrient recycling is a fundamental process for the functioning of tropical forests; however, anthropogenic activities such as mining could affect this process in tropical ecosystems. Given that little is known about the effects of mining on nutrient recycling in tropical forests, the objective was set to evaluate the influence of mining on nutrient cycling in tropical rainforests of the Colombian Pacific. Additionally, the hypothesis that nutrient cycling could be lower in post-mining areas was evaluated. To evaluate the effect of mining on nutrient cycling, permanent plots were established in mature and post-mining forests. In both forests, soil acidity, aluminum (Al), organic matter (OM), total nitrogen (N), available phosphorus (P), magnesium (Mg), potassium (K), calcium (Ca), and effective cation exchange capacity (ECEC) were considered. Likewise, the litter production, decomposition, and accumulation on the ground were determined; additionally, nutrient content and nutrient use efficiency (NUE) were determined. It was observed that mining influenced the nutrient contents of the soil in a different way. It was evident that total N and soil OM were similar in both forests, while the contents of P, K, Ca, Mg, Al, and ECEC available were higher in post-mining. The litterfall production and litter mass accumulation on the ground were greater in post-mining, while litter decomposition was greater in mature forests. In mature forests, there was higher foliar content of N, Ca, and B and, in addition, higher NUE of Ca. However, in post-mining, there was higher leaf content of K, Mg, P, Fe, Cu, Mn, and Zn and, in addition, greater NUE of N, P and K. In conclusion, an increase in post-mining nutrient cycling was noted as a strategy for nutrient conservation, and recovery of the functioning and maintenance of productivity in degraded Pacific ecosystems. Consequently, it is expected that in the future, if mining continues in the region, productivity and nutrient recycling will be altered.

Niche separation of three species of tree-rat (black-footed tree-rat, M. gouldii, golden-backed tree-rat, Mesembriomys macrurus, and brush-tailed rabbit-rat, Conilurus penicillatus) on the Mitchell Plateau, Western Australia

Context Distribution and abundance of the three northern Australian tree-rat species, Conilurus penicillatus, Mesembriomys macrurus and M. gouldii, have contracted significantly since European settlement. All three species were recorded from the Mitchell Plateau, Western Australia, in the 1980s, enabling their niche separation to be assessed. Despite this study being conducted in 1987, the results remain relevant for conservation strategies for these species. Aims To determine the ecological separation among three tropical tree-rat species by documenting habitat preferences, habitat use and diet. Methods Live-trapping, radiotracking and spotlighting were used to assess relative abundance, habitat preference and movements of each species at nine sites on the Mitchell Plateau. Diet was determined using scat analysis; vegetation communities were described and characterised by pattern analysis. Key results C. penicillatus (number of individuals trapped (n) = 24) was most abundant, followed by M. macrurus (n = 8) and M. gouldii (n = 2). Mature open forest with a well-developed understorey was preferred by the predominantly arboreal M. gouldii (1 site), M. macrurus occupied more varied habitats (four sites), especially ecotones between vine thicket and open eucalypt forest and the boulder edges of the plateau, and C. penicillatus occupied the greatest variety of habitats (four sites) in open eucalypt woodland with a diverse shrub layer and ground cover almost absent to very dense, tall grass. Diet analysis identified M. gouldii as a frugivore (fruits, some flowers), M. macrurus as an omnivore (seeds, fruits, flowers, termites, other invertebrates), and C. penicillatus as a generalist (monocot and dicot leaves, seeds, flowers, fruits, some arthropods). Conclusions The largest of the species, M. gouldii, appeared to have the narrowest ecological niche, preferring more stable, structurally diverse, mature open forest that is infrequently burnt. The mid-sized M. macrurus occupies a broader range of habitats, particularly ecotones between vine thickets and eucalypt forest/woodland and woodland. C. penicillatus preferred open eucalypt woodland with a variable understorey. Implications With a changing climate, increased fire frequency, habitat degradation by introduced herbivores and predation by cats across the tropical savanna distribution of these threatened tree-rats, this study provides data to underpin actions that may ensure their survival.

Taxonomic and functional diversity along successional stages on post-coalmine spoil heaps

Coal is the most abundant fossil fuel in Europe, but the excavation of hard coal has covered large areas with disposed rock waste, and turned the natural habitats into disturbed novel ecosystems with harsh conditions differ in time and space. To examine the spontaneous complex successional gradient, we studied a large number of post coalmine heaps in Upper Silesia, which differ in vegetation type and age. Cluster analysis based on plant community composition (367 species in total) separated all surveyed plots on coal mining spoil heaps with herbaceous vegetation from Late Stage (LS) forests aged 14–56 years. Furthermore, the herbaceous vegetation was sub-grouped to three stages: Initial Stage (IS) aged 2–5 years, Early Stage (ES) aged 3–8 years and Mid-Stage (MS) aged 5–12 years. MS vegetation was characterised by the highest species richness and diversity (47 and 2.79) compared to ES (30 and 2.18) and IS (9 and 1.6), but higher species number and a similar diversity index occurred in LS (37 and 2.81). Functional diversity (FD) and community weighted mean (CWM) of nine functional traits showed higher (23.1) functional richness, higher (0.72) functional divergence, higher (4.5) functional dispersion, and higher value (24.4) of Rao’s quadratic entropy in LS compared to those calculated from the first three stages. Species at the initial successional stage (IS) were characterised by lower canopy height, seed mass, higher lateral spread, and specific leaf area (SLA). Additionally, the lowest (0.22 mg CO2 per hour per square metre) soil respiration (Sr) rate was recorded from IS compared to (0.53, 0.82 and 1.00) from ES, LS and MS, respectively. The soil water content (SWC) was the most important factor affecting the soil respiration, while the soil temperature (St) did not follow the well-studied relationship between soil respiration and soil temperature. Our spatial and temporal analyses illustrated changes in plant community assembly processes in the course of spontaneous vegetation succession on post coalmine spoil heaps. The importance of trait mediated abiotic filtration in community assembly in initial-, early-, and mid-stages of succession with an increase in competitive exclusion at the late successional stage was emphasized.

CloudRoots-Amazon22: Integrating Clouds with Photosynthesis by Crossing Scales

Abstract How are rain forest photosynthesis and turbulent fluxes influenced by clouds? To what extent are clouds affected by local processes driven by rain forest energy, water, and carbon fluxes? These interrelated questions were the main drivers of the intensive field experiment CloudRoots-Amazon22 which took place at the Amazon Tall Tower Observatory (ATTO)/Campina supersites in the Amazon rain forest during the dry season, in August 2022. CloudRoots-Amazon22 collected observational data to derive cause–effect relationships between processes occurring at the leaf level up to canopy scales in relation to the diurnal evolution of the clear-to-cloudy transition. First, we studied the impact of cloud and canopy radiation perturbations on the subdiurnal variability of stomatal conductance. Stoma opening is larger in the morning, modulated by the cloud optical thickness. Second, we combined 1-Hz frequency measurements of the stable isotopologues of carbon dioxide and water vapor with measurements of turbulence to determine carbon dioxide and water vapor sources and sinks within the canopy. Using scintillometer observations, we inferred 1-min sensible heat flux that responded within minutes to the cloud passages. Third, collocated profiles of state variables and greenhouse gases enabled us to determine the role of clouds in vertical transport. We then inferred, using canopy and upper-atmospheric observations and a parameterization, the cloud cover and cloud mass flux to establish causality between canopy and cloud processes. This shows the need for a comprehensive observational set to improve weather and climate model representations. Our findings contribute to advance our knowledge of the coupling between cloudy boundary layers and primary carbon productivity of the Amazon rain forest.

Landscape Ecological Structures and Patterns for Green Space Conservation in Forest Monasteries in Northeast Thailand

The green spaces in Wat Pah play an important role in forest conservation in Thailand. This study identified and analyzed the structures and patterns of landscape ecology in Wat Pah Nanachart, Ubon Ratchathani Province, to guide a conceptual framework for green space conservation in forest monasteries. Spatial analysis and modeling using geoinformatics technology were employed to recognize and characterize these landscapes. Information on the green space conservation and management of Wat Pah was also obtained using an in-depth interview and site observation. The results revealed that most of the green space in Wat Pah is forest, characterized by an ecological matrix and a dry evergreen forest. The forest structure can be divided into three canopies, dominated by the Dipterocarpaceae family, which has regenerated into upper and lower canopies. It is an edge matrix and ecological corridor connected to the internal and external green spaces of Wat Pah. It plays an important role in supporting cultural, religious, and aesthetic activities for ordained monks and Buddhists. The spatial landscape model can be divided into three main zones: Thoranisangha, Buddhawas, Sanghawas. Thoranisangha is an open space covered with traditional and artificially planted tree species. It is located in front of the temple and designed for public utilities in the context of managing and conserving the remaining trees. Buddhawas is a semi-open space mostly covered with traditional tree species. It represents Buddhism’s identity and uniqueness and is used for religious ceremonies and dissemination—listening to sermons, meditating, and praying. Meanwhile, Sanghawas is covered with natural forest and contains residences for monks that are designed to be in harmony with the forest ecosystem.

Structure and composition of a canopy-beetle community (Coleoptera) in a Neotropical lowland rainforest in southern Venezuela.

Species richness, community structure and taxonomic composition are important characteristics of biodiversity. Beetle communities show distinct diversity patterns according to habitat attributes. Tropical rainforest canopies, which are well known for their richness in Coleoptera, represent such a conspicuous life zone. Here, I describe a canopy-inhabiting beetle community associated with 23 tree species in a Neotropical lowland rainforest. Adult beetles were sampled manually and in aerial traps using a large tower crane for a cumulative year. The sample revealed 6738 adult beetles, which were assigned to 862 (morpho-)species in 45 families. The most species-rich beetle families were Curculionidae (n = 246), Chrysomelidae (n = 121) and Cerambycidae (n = 89). The most abundant families were Curculionidae (n = 2746) and Chrysomelidae (n = 1409). Dominant beetle families were found in most assemblages. The beetle community consisted of 400 singletons (46.4%). A similar proportion was evident for assemblages of single tree species. I found that 74.5% of all beetle species were restricted in their occurrence on host trees to the phenological season and time of the day. This daily and seasonal migration causes patterns similar to mass effects and therefore accounts for the high proportion of singletons.

Estimation of Picea Schrenkiana Canopy Density at Sub-Compartment Scale by Integration of Optical and Radar Satellite Images

This study proposes a novel approach to estimate canopy density in Picea Schrenkiana var. Tianschanica forest sub-compartments by integrating optical and radar satellite data. This effort is aimed at enhancing methodologies for forest resource surveys and monitoring, particularly vital for the sustainable development of semi-arid mountainous areas with fragile ecological environments. The study area is the West Tianshan Mountain Nature Reserve in Xinjiang, which is characterized by its unique dominant tree species, Picea Schrenkiana. A total of 411 characteristic factors were extracted from Gaofen-2 (GF-2) sub-meter optical satellite imagery, Gaofen-3 (GF-3) multi-polarization synthetic aperture radar satellite imagery, and digital elevation model (DEM) data. Consequently, 17 characteristic parameters were selected based on their correlation with canopy density data to construct an estimation model. Three distinct models were developed, including a multiple stepwise regression model (a linear approach), a Back Propagation (BP) neural network model (a neural network-based method), and a Cubist model (a decision tree-based technique). The results indicate that combining optical and radar image characteristics significantly enhances accuracy, with an Average Absolute Percentage Precision (AAPP) value improvement in estimation accuracy from 76.50% (with optical image) and 78.50% (with radar image) to 78.66% (with both). Of the three models, the BP neural network model achieved the highest overall accuracy (79.19%). At the sub-component scale, the BP neural network model demonstrated superior accuracy in low canopy density estimation (75.37%), whereas the Cubist model, leveraging radar image characteristics, excelled in medium density estimations (87.46%). Notably, the integrated Cubist model combining optical and radar data achieved the highest accuracy for high canopy density estimation (89.17%). This study highlights the effectiveness of integrating optical and radar data for precise canopy density assessment, contributing significantly to ecological resource monitoring methodologies and environmental assessments.

Eksplorasi Mikroflora Alami Cairan Nepenthes mirabilis (Lour) Druce di Kawasan Hutan Penelitian dan Pendidikan Biologi Universitas Andalas

Indonesia is a country that is rich in flora and fauna diversity, one of the unique flora in Indonesia is Nepenthes. This bag serves to trap insects or other small animals, the Biology Education and Research Forest (HPPB) is located in the Andalas Limau Manis University campus area which is classified as lowland tropical rain forest which is the habitat of Nepenthes, in the Biology Education and Research Forest (HPPB) this type of pitcher plant, namely Nepenthes mirabilis. Nepenthes mirabilis is a plant that is able to digest insects trapped in pockets at the ends of its leaf tendrils, so it is classified as a carnivorous plant. Microorganisms play an important role in breaking down organic materials into inorganic ones available to plants. Types of bacteria and bacterial populations greatly determine the decomposition process of animals that have been trapped in the bag as a source of nutrients for Nepenthes plants. This study aims to explore the natural microflora of Nepenthes mirabilis fluids, determine the proportional presence of potential bacteria, and determine the in vitro potential of chitinolytic bacteria from Nepenthes mirabilis fluids. This study used a survey method which was analyzed descriptively. The results showed that Nepenthes mirabilis fluid contained the presence of Fermentative, Amylolytic, Proteolytic, Chitinolytic and Lipolitical bacteria. Nepenthes mirabilis liquid in open bags contained chitinolytic bacteria, the highest presence of chitinolytic bacteria was found in MBB samples (20,104 cfu/ml) and MBA samples (18,104 cfu/ml). .28), fermentative (2.33 and 2.00), amylolytic (1.42 and 1.28), proteolytic (2.00 and 2.00), lipolytic (1.75 and 1.28).

Assessing potential benefits of visits to neighborhoods with higher tree canopy coverage using mobility data: Associations with cardiovascular health outcomes in twenty US metropolitan areas

BackgroundResearch on health benefits due to exposure to green space, such as tree canopy coverage, has predominantly focused on canopy coverage in home neighborhoods. Yet exposures to tree canopy coverage in other spaces visited during the week or on weekends outside the home neighborhoods remains largely unexplored. ObjectivesWe examined whether differences in coverage levels of tree canopy in neighborhoods visited compared to home neighborhoods was associated with lower prevalence of coronary heart disease (CHD) and stroke, adjusting for exposure to home canopy coverage. We further investigated if the associations varied across levels of home canopy coverage, and if they were more pronounced on weekdays or weekends. MethodsWe used 2018 mobile phone data from the twenty largest U.S. Metropolitan Statistical Areas (MSAs). For each home census tract, we derived a weighted tree canopy coverage exposure from all visited tracts based on the proportion of visits to other tracts by home tract residents. We subtracted home canopy coverage from the weighted canopy coverage in each of the visited tracts to calculate tract-specific differences. We evaluated associations between differences in tree canopy coverage and prevalence of CHD and stroke via spatial error models, adjusting for tract-level home canopy coverage, MSA, socioeconomic and built environment characteristics. ResultsFor every ten-percentage-point increase in tree canopy coverage in visited tracts relative to home tracts, there was a 0.32–0.34% decrease in stroke prevalence. Association with CHD prevalence was not observed after adjusting for spatial autocorrelation. Variations between weekdays and weekends were minimal. The difference in tree canopy coverage was associated with CHD prevalence only for home tracts with low tree canopy coverage, while the difference was associated with stroke prevalence across home tracts with low, moderate, and high tree canopy coverage, with diminishing effect size. DiscussionThis study identified that greater tree canopy coverage in visited neighborhoods relative to home neighborhoods was associated with lower stroke prevalence, and associations varied across home neighborhoods with different tree canopy coverage levels. It emphasized the need to factor in the neighborhood mobility networks in urban planning initiatives to promote cardiovascular health.

Study on plant protection unmanned aerial vehicle spraying technology based on the thrips population activity patterns during the cotton flowering period.

Over the years, thrips have transitioned from a minor nuisance to a major problem, significantly impacting the yield and quality of cotton. Unmanned aerial vehicles (UAVs) for plant protection have emerged as an effective alternative to traditional pesticide spraying equipment. UAVs offer advantages such as avoiding crop damage and enhancing pesticide deposition on the plants and have become the primary choice for pesticide application in cotton fields. In this study, a 2-year field experiment found that the thrips population in a cotton field in Xinjiang, China, exhibited gradual growth during the early flowering phase, peaking in late July. The thrips population gradually shifted from the lower canopy to the upper canopy as the cotton flowers opened layer by layer. From 09:00 to 11:00 (GMT+8) and 19:00 to 21:00 (GMT+8), thrips mainly flew outside the flowers, while from 17:00 to 19:00 (GMT+8), they mostly inhabited the inner whorls of flowers. The insecticides 10% cyantraniliprole oil dispersion and 10% spinetoram suspension concentrate, sprayed by UAV, had the best control effect on thrips, with 80.51% and 79.22% control effect after 7 days of spraying, respectively. The optimal spraying time for 10% cyantraniliprole oil dispersion was 19:00 (GMT+8), and the control effect on thrips reached 91.16% at 7 days of spraying. During the cotton flowering period, thrips inhabited flowers in the evening and flew outside during the day. The best control effect on thrips was achieved with UAV-sprayed 10% cyantraniliprole oil dispersion at 19:00 (GMT+8).

Shrimp habitat selection dependence on flow within Zostera marina canopies

Even though hydrodynamic conditions play an important role in shallow costal ecosystems such as enhancing primary production by the remobilization of nutrients, they could represent a potential threat to motile benthic animals because they can dislodge them and restrict their movements, thereby impacting their distribution within the ecosystem. Seagrass canopies are critical habitats that shelter many organisms against predators and adverse hydrodynamic conditions, however, they have been declining over time, resulting in seagrass fragmentation and low canopy densities. The shrimp Palaemon adspersus is an epifaunal species that thrives in Zostera marina seagrass, and therefore can offer insight into the impact canopy fragmentation is having on its behavioral patterns. In a laboratory flume with unidirectional flow, P. adspersus individuals were exposed to flow velocities in sand bottoms covered with Z. marina canopies, and their distribution studied as a function of both the canopy density and the current velocity. Flow velocities above 3 cm s−1 started to dislodge P. adspersus individuals, thereby reducing their tolerance to the flow. However, under flow velocities ranging from 3 cm s−1 to 21 cm s−1, they preferred to shelter within the seagrass canopies with intermediate densities higher than 150 shoots m−2, compared to bare sand. The patch density at which individuals found patch sheltering decreased linearly as the current velocity increased, indicating that individuals were unable to withstand the velocity of the flow. For current velocities above 21 cm s−1, P. adspersus were unable to tolerate the flow velocity, and so were dislodged from the canopy. This study highlights the importance of protecting eelgrass, as the ever-decreasing meadows are making P. adspersus even more vulnerable to the high flow rates.

Effects of diffuse light on the gross ecosystem primary productivity of a winter wheat (Triticum aestivum L.) cropland in northern China

Diffuse light is produced by clouds and aerosols in the atmosphere. Exploring the effects of diffuse light on ecosystem productivity is important for understanding the terrestrial carbon (CO2) cycle. Here, 2 years of gross ecosystem primary productivity (GEP) from a (winter) wheat cropland in China was assessed using eddy covariance technology to explore the effects of diffuse photosynthetic active radiance (PAR) on wheat GEP. Wheat GEP increased significantly and positively along with diffuse PAR. In addition, wheat GEP was significantly affected by total PAR, air temperature, and vapor press deficit in different diffuse PAR fraction (fDIF) change stages. Because significant autocorrelations existed among the controlling factors, a path analysis was used to quantify the effects of diffuse light on GEP. Diffuse PAR was the primary and secondary importance factors affecting GEP with direct path coefficients of 0.54 and 0.48, respectively, in different fDIF change stages. A multilayer canopy model revealed that the middle and lower canopy levels intercepted more light when diffuse PAR increased. This resulted in the photosynthetic enhancement of middle and lower canopy levels, which contributed approximately 65% and 35%, respectively, to the increase in photosynthesis for the entire canopy (~ 30.5%). Overall, our study provided new evidence regarding the importance of diffuse light for CO2 uptake in agroecosystems, which is important for predicting the responses of ecosystem CO2 budgets to future climate-related light changes.

Reconstruction of NDVI based on Larix gmelinii tree-rings during June–September 1759–2021

Investigating the long-term dynamics in the canopy proves to be difficult due to the short observational records of the normalized difference vegetation index (NDVI). To explore the linkage between tree growth, NDVI dynamics and large-scale atmospheric circulation in the Greater Khingan Mountain, Northeast China, we established a chronology of Larix gmelinii tree ring width at three elevations (870–920 m, 1,100–1,150 m and 1,270–1,320 m) in the northern foothills of the mountain range. We then calculated the correlations between the tree ring chronologies and NDVI and climate factors, and reconstructed the NDVI time series from June to September 1759–2021 in the region based on the middle-elevation tree ring chronology. The results identify the positive effect of temperature (r = 0.56, p &amp;lt; 0.01) and the negative effect of precipitation (r = −0.44, p &amp;lt; 0.01) in the growing season as the main influencing factors of NDVI for the study period (1981–2019). The 11-year moving average of the reconstructed NDVI series reveals two periods of high canopy vigor (1898–1926 and 2009–2013) and three periods of low canopy vigor (1860–1962, 1882–1888 and 1968–1977) in the last 263 years. These periods correspond to drought events recorded in the historical literature. Wavelet analysis shows that the reconstructed sequences exhibited 11–13, 23–25, and 39–42 years period variations. Integrating this with spatial correlation analysis reveals that tree growth in the Mangui region was impacted by the combined effect of the North Pacific Decadal Oscillation and the North Atlantic Multidecadal Oscillation. The results of this paper provide a reference for the study of vegetation change patterns in the northern foothills of the Greater Khingan Mountains.