Ecosystem Disturbance Research Articles

Changes in throughfall induced by low‐severity fire in a coniferous and broadleaved mixed forest

AbstractForest fires, as a prominent main natural disturbance in forest ecosystems, have a critical influence on hydrological processes through the alteration of forest stand structure. Despite throughfall (TF) being the dominant component of rainfall partitioning in forest ecosystems, limited research has thoroughly investigated how forest fire affects the spatial and temporal patterns of TF. This study examined TF patterns in response to low‐severity fire in a coniferous and broadleaved mixed forest in Central China. Our results showed that TF exhibited an increasing trend regarding gross rainfall, and its variability decreased with increasing gross rainfall regardless of burning states. Low‐severity fire induced a considerable enhancement in TF rate, enhancing it from 71.1% to 77.9%, and increased the coefficient of variation from 19.4% to 23.9%. Additionally, TF temporal patterns of burned forest were found to be marginally less stable than unburned forest. We used a sample size of 16 and 25 for unburned and burned forests, respectively, to accurately and reliably acquire TF with an accepted error of 10% and a 95% confidence level. Our findings suggest that low‐severity fire can enhance TF yield and variability, decrease temporal stability. Moreover, we recommend increasing the sample size of burned forest to ensure the collection of representative TF. These findings contribute to a deeper understanding and improve the prediction of forest hydrological processes in response to fire and optimize the sampling scheme of TF.

Rapid, Landscape-Scale Assessment of Cyclonic Impacts on Mangrove Forests Using MODIS Imagery

Cyclones are a key disturbance in mangrove ecosystems, but it is challenging to assess post-storm impacts over large areas, along with the recovery of these systems at broad temporal scales. Given the high frequency of these events in the Sundarbans region, prompt and consistent assessment of vegetation conditions is an important research need. Several studies have assessed the impact of an extreme cyclone event in 2007 (Sidr); however, there is little agreement between the extent and severity of the disturbance footprint of the cyclone, and very few studies attempted to assess vegetation recovery. We used a MODIS (Moderate Resolution Imaging Spectroradiometer) time series (2001–2010) to calculate monthly plant productivity anomalies in Google Earth Engine. We summarized dry season anomalies to assess post-storm vegetation change and evaluate the recovery time. Approximately 2100 km2, primarily on the east side, were impacted by Sidr. The number of damaged pixels was reduced by 55% the following dry season (2008) and 93% in the dry season of 2009, indicating a near-full recovery 26 months after the event. Our results provide an additional line of evidence to provide a rapid assessment of the post-storm vegetation damage. The simple framework used can provide a comprehensive view of the extent of the damage, including lag effects on vegetation, in just a matter of months after the event.

Mosquito community composition shapes virus prevalence patterns along anthropogenic disturbance gradients.

Previously unknown pathogens often emerge from primary ecosystems, but there is little knowledge on the mechanisms of emergence. Most studies analyzing the influence of land-use change on pathogen emergence focus on a single host-pathogen system and often observe contradictory effects. Here, we studied virus diversity and prevalence patterns in natural and disturbed ecosystems using a multi-host and multi-taxa approach. Mosquitoes sampled along a disturbance gradient in Côte d'Ivoire were tested by generic RT-PCR assays established for all major arbovirus and insect-specific virus taxa including novel viruses previously discovered in these samples based on cell culture isolates enabling an unbiased and comprehensive approach. The taxonomic composition of detected viruses was characterized and viral infection rates according to habitat and host were analyzed. We detected 331 viral sequences pertaining to 34 novel and 15 previously identified viruses of the families Flavi-, Rhabdo-, Reo-, Toga-, Mesoni- and Iflaviridae and the order Bunyavirales. Highest host and virus diversity was observed in pristine and intermediately disturbed habitats. The majority of the 49 viruses was detected with low prevalence. However, nine viruses were found frequently across different habitats of which five viruses increased in prevalence towards disturbed habitats, in congruence with the dilution effect hypothesis. These viruses were mainly associated with one specific mosquito species (Culex nebulosus), which increased in relative abundance from pristine (3%) to disturbed habitats (38%). Interestingly, the observed increased prevalence of these five viruses in disturbed habitats was not caused by higher host infection rates but by increased host abundance, an effect tentatively named abundance effect. Our data show that host species composition is critical for virus abundance. Environmental changes that lead to an uneven host community composition and to more individuals of a single species are a key driver of virus emergence.

Environmental heterogeneity associated with boat activity shapes bacteria and microeukaryotic communities with discrepant response patterns

With the development of global tourism, tourist boats, a significant form of anthropogenic disturbance, are having an increasingly serious impact on the structure and function of aquatic ecosystems. In this study, the effects of different intensities of tourist boat activities on the microbial communities of West lake, were investigated by high-throughput sequencing. The results showed significant differences in the composition of bacterioplankton and microeukaryotic communities between the high-intensity boat activity (HIBA) area and low-intensity boat activity (LIBA) area. Variation partitioning analysis showed that environmental factors contributed the most to microbial community variation, and the effect of boat activities on microbial communities mainly occurred through coupling with environmental factors. The contribution of boat activity to microbial community changes occupies the second place, the first being environmental factors. Co-occurrence network analyses showed that microbial communities in the HIBA area had more nodes and edges, higher connectivity and lower modularity than in the LIBA area, suggesting a more complex and stable network. Networks of associations between potential keystone taxa and environmental factors reveal the way in which boat activity affects microbial communities. The bacterial community responded strongly to environmental factors associated with boat activities, whereas the microeukaryotic community was more likely to be regulated by interspecific interactions. This also suggests that when faced with disturbances from the boat activity, microeukaryotes might exert a stronger direct resistance effect compared to bacterioplankton. These findings imply that bacterioplankton and microeukaryotes demonstrate distinct response patterns in the presence of disturbance caused by boat activity. Our research expand our understanding of the effects of boat activities on aquatic ecosystems and provide further insights into the assessment of anthropogenic disturbances in aquatic ecosystems.

Estimation of Soil Loss for Different Soil Series, Tillage Management and Slopes under Soybean Cropping in Malwa Agro-Climatic Zone

The soil erosion can cause a reduction in agricultural productivity, ecosystem disturbances, and pollution of water. Physical and climatic features of a catchment such as topographic conditions, land use land cover, rainfall intensity, and the soil characteristics are the key significant factors of the soil erosion. The loss of the top fertile soil nutrients is intensely increasing. In present study soil loss for 12 soil series viz., Kheri, Bararia, Junapania, Namali, Dhamaniya Diwan, Dhodar, Surajpura, Paroliya, Ratangarh, Khermaliya, Morwan and Hathipura and 3 different tillage management viz., conventional tillage, ridge and furrow system and no tillage system under soybean crop in Malwa Agro-climatic Zone in central India has been estimated. The soil loss for four different sloes viz., 1%, >1% to < 3%, >3 to <5% and >5% under these soil series and management practices have been studied. The results of the study revealed that soil loss found decreased with decrease in slope and vice-versa. Similarly, the soil loss was found higher under conventional tillage (4.134 t acre-1 y-1) as compared to the ridge and furrow system (1.447 t acre-1 y-1) and no tillage system (1.033 t acre-1 y-1). The Bararia soil series (4.196 t acre-1 y-1) found most vulnerable to the soil loss whereas the Dhodar soil series (1.036 t acre-1 y-1) was found resistant to soil loss under soybean cropping in Malwa Agro-climatic Zone.

First Data on Species Composition and Development Cladocera (Crustacea: Branchiopoda) in Mire Ecosystems (Kaliningrad Region, Russia)

The original data on Cladocera fauna in standing-water and stream habitats of mire ecosystems were obtained for the first time in the Kaliningrad region during the research study on large raised bogs (Zehlau and Bolshoye) and drainage canals of 6 peatlands affected by peat extraction. In the studied wetland ecosystems, 41 species of Cladocera were recorded in total, including a number of rare and vulnerable taxa (Flavalona rustica, Scapholeberis microcephala, Streblocerus serricaudatus and Holopedium gibberum). The four species of Cladocera are new species for the Kaliningrad region which were not reported here before. Cladocera played a vital role in the studied bog pools and waterlogged habitats in peatlands as a key group of organisms that forms here a significant part of the zooplankton biomass due to the abundance and intensive production in the water bodies. The secondary filter feeders and predators were the most abundant in bog ecosystems. The cladoceran fauna in the intact bog ecosystems, especially the Zehlau raised bog, was the most diverse and unique. Nevertheless, the cladoceran assemblages in the disturbed ecosystems of drainage canals retained certain features of the natural water bodies. The latter fact is important in applied respect enabling to consider these canals as refugia that have potentials for natural restoration of the cladoceran fauna during the peatland rewetting programme on the Carbon Polygon in the Kaliningrad region.

Effects of Douglas fir cultivation in German forests on soil seepage water quantity and quality

Norway spruce (Picea abies L.) has been a key tree species and timber source in European forests the last centuries and is increasingly suffering from drought and bark beetle infestations due to climate warming. Current management options include replacing of Norway spruce monocultures with pure and mixed stands of European beech (Fagus sylvatica) that is the naturally dominating tree species in Central Europe. Additionally, Douglas fir (Psudotsuga menziesii), a tree species with high water use efficiency and drought tolerance, is being increasingly cultivated to increase the resilience of European forests and meet the future demand of conifer timber in a warming climate. We studied the seepage water quantity and quality with a particular focus on the nitrate (NO3–) concentration and N leaching under pure and mixed stands of Douglas fir, Norway spruce, and European beech at seven sites in Germany. Additionally, we investigated seepage water concentrations of SO4-S, Ca, Mg, K, Al and hydrological variables (interception, canopy throughfall, transpiration). Looking at the seepage water quantity and quality, the best management option is the cultivation of pure beech stands. However, this is associated with the well-known risk of monocultures concerning ecosystem disturbance. Beech stands showed the highest seepage water quantities and the lowest seepage water concentrations of major cations and anions, including NO3–. Seepage water quantity was the smallest under pure Douglas fir compared to spruce and beech stands. The composition effects of stand tree species on seepage water quality and nutrient leaching were site-dependent. At N-rich sites, pure Douglas fir stands showed higher seepage water NO3– concentrations than spruce and beech stands, whereas the tree species effects were small at N-poor sites. With respect to seepage water quantity and quality, cultivation of mixed Douglas fir–beech stands is a promising option for producing conifer timber and at the same time avoiding increased disturbance risks of mono-species forests under a warmer climate. Our results support the recommendation of mixed Douglas fir–beech stands based on soil quality, ecosystem resilience, and forest economic studies.

Climate change greatly escalates forest disturbance risks to US property values

Anthropogenic climate change is projected to drive increases in climate extremes and climate-sensitive ecosystem disturbances such as wildfire with enormous economic impacts. Understanding spatial and temporal patterns of risk to property values from climate-sensitive disturbances at national and regional scales and from multiple disturbances is urgently needed to inform risk management and policy efforts. Here, we combine models for three major climate-sensitive disturbances (i.e., wildfire, climate stress-driven tree mortality, and insect-driven tree mortality), future climate projections of these disturbances, and high-resolution property values data to quantify the spatiotemporal exposure of property values to disturbance across the contiguous United States (US). We find that property values exposed to these climate-sensitive disturbances increase sharply in future climate scenarios, particularly in existing high-risk regions of the western US, and that novel exposure risks emerge in some currently lower-risk regions such as the southeast and Great Lakes regions. Climate policy that drives emissions towards low-to-moderate climate futures avoids large increases in disturbance risk exposure compared to high emissions scenarios. Our results provide an important large-scale assessment of climate-sensitive disturbance risk to property values to help inform land management and climate adaptation efforts.

EXPANDING THE SCIENTIFIC WORLDVIEW OF ECOLOGY STUDENTS

In the article, the authors reveal the methods of expanding the formation of the scientific ecological worldview of student youth in the "Ecology" field of study. The modern educational process requires not only the assimilation of scientific knowledge, but also the education of a moral, ethical, responsible personality in relation to nature, the biosphere, any form of life, as the most important human value.
 Life is the most unique and highest value on the planet. Preserving life in all forms and manifestations is the main goal of a modern ecologist today. Creating an artificial environment for his habitat, man, in pursuit of economic profit, began to treat the biosphere in a consumerist way, destroying, destroying, bringing it to a tense state. This attitude towards nature leads not only to the destruction of ecosystems and the biosphere, but also to the impoverishment of the spiritual and moral foundations of a person's personality. In the conditions of the growing ecological crisis, it is necessary to change the attitude towards nature, to understand the value of any form of life. It is nature that can inspire and develop the spiritual and moral basis of a person. In this aspect, environmental education, aimed at changing and improving the scientific outlook, acquires special significance. Only on the basis of a new type of relationship between man and nature is a way out of this crisis possible. In the system of environmental education, new relevant environmental areas and training profiles are emerging. There are new tasks for students.Employers increasingly set high demands for future ecologists: they demand a high level of professional knowledge, skills and abilities, clearly navigate the problems of ecosystem disturbances, apply the latest methods of restoration, quickly and correctly make decisions in situations of a natural and man-made nature, the ability to own innovative technologies.
 In connection with the new requirements for a modern ecologist, there is a need to expand the educational process and innovative pedagogical approaches, to expand the scientific outlook of higher education students.

Toxicopathic effects of waterborne Cd in sole juveniles, a prospective pollution monitoring sentinel for estuarine ecosystems

IntroductionEstuarine ecosystems are under high anthropogenic pressure and receive a wide Q7 variety of contaminants, including metals. They can remain trapped in estuarine sediments at high concentrations for long periods but eventually they can be released to the overlying water and become toxic for the resident benthic biota. As a consequence, biomonitoring programs surveying the health status of estuaries and coastal areas count with benthic species for the assessment of health disturbances in these specific ecosystems. The present investigation aims at recognizing toxicopathic effects elicited in estuarine life stages of the benthic fish Solea senegalensis on exposure to waterborne Cd, a model compound for metal contamination.MethodsBiological responses to metal exposure were assessed based on the application of a “biomarker + histopathology” approach. Two-year old sole juveniles were exposed to various concentrations of waterborne Cd for 3 and 7 days (Control; Low Cd: 1 µg/l; Mid Cd: 10 µg/l and High Cd: 1000 µg/l). Liver samples were collected for chemical analysis at day 7. Biological samples were collected at days 3 and 7 for biochemical (brain and liver), histochemical (liver) and histopathological analysis (liver, gills and gonad).ResultsBrain acetyl cholinesterase was inhibited after 7 days exposure, indicating neurotoxic effects on exposure to 1000 µg Cd/l. Hepatic catalase and glutathione-Stransferase were induced at day 3 and inhibited at day 7, which suggests a bell-shaped response. A dose-dependent lysosomal membrane destabilization in hepatocytes was recorded at day 7. In parallel, histopathological lesions in gills, liver and gonad were more frequent at day 7 in soles exposed to high Cd concentrations.DiscussionOverall, the “biomarker + histopathology” approach revealed that waterborne Cd causes toxicopathic effects in sole juveniles upon exposure to environmentally relevant concentrations (10 µg Cd/l). The effects were clearly time dependent, and thus it is conceivable that more severe biological effects would be elicited by these low concentrations of Cd at longer exposure periods. Therefore, biomarkers and histopathology in combination provide early-warning indications of altered health status after waterborne Cd exposure in sole juveniles, a prospective sentinel for biological effects assessment of metal contamination in pollution monitoring programs in estuaries and coastal areas.

Epidemiological data for WNV in Greece during last decade

WNV is a single strand RNA zoonotic virus, responsible for mild fever to severe, lethal neuroinvasive disease. The aim of the study is to investigate and record the epidemiological data on WNV in Greece during last 10 years. Furthermore, to approach the main causes of the incidences and the factors that contribute in the virus epidemiology, the geographic areas and the time period of virus circulation, as well as the areas of the incidences’ appearance based on the data from the entomological surveillance that take place in Greece. Moreover, to investigate the possibility of WNV disease to become an endemic one. We reviewed published papers, articles, studies, review articles, books, in PubMed NCBI, EMBASE, Scopus, Google Scholar, CDC, ECDC, WHO, that refer to epidemiological surveillance data and guidelines for WNV in Greece during last decade. The search carried out in July 2022. During 2010-2014 and 2017-2021, confirmed cases from WNV have been declared in several areas all over Greece, especially during summer and autumn when the mosquitoes circulation is present. Last decade WNV shows an increased rate, mainly in areas of Central Macedonia and Attica. The causes of WNV appearance are the climate change, the ecosystem disturbance and the economic crisis that leads to sprays reduction. To deal with the endemicity of the disease, in the frames of Public Health protections, actions of entomological surveillance were carried out during the transmission period in 2020. Summarizing, through continuing epidemiological disease surveillance, the mosquito control via integrated programs, as well as the personal safety measures against mosquitoes still represent the most accepted measures for the disease control.

Calibrating a process-based simulation model for the Acadian forest region

Climate change is projected to have profound impacts on Canada’s Acadian Forest Region (AFR). However, large uncertainties arising from climate change and increasing disturbance activity pose challenges for forest management decisions. Process-based (mechanistic) simulation models offer a means by which vulnerabilities and different management strategies can be tested under multiple climate and disturbance regimes. However, applying these complex models can be dauting, especially for novice modelers and forest practitioners; nonetheless, this complexity is increasingly necessary to more realistically project changes in forest growth and composition, ecosystem services, biodiversity, disturbance regimes, and the spread of forest pests. Here, we present a methodology for calibrating and validating iLand (v1.1.1), a landscape-scale, process-based forest model that offers a novel approach for assessing the feedback between individual trees and their environment (ecosystem processes, climate, and disturbance). For the first time, 18 tree species were parameterized and calibrated for the AFR and model performance was evaluated against independent field observations at the tree population and stand level. iLand was able to accurately emulate the dynamics of individual tree species populations as well as the succession of mixed-species forest stands across a range of soil conditions and is now ready to be used to simulate future forest dynamics of the AFR. We also discuss calibration method selection and the potential impacts of model and project structure in relation to our project. As the accessibility and usability of process-based forests models increases, our work provides a unique case study for forest managers looking to expand their toolbox.

LEGAL REFLECTION ON SPURRING WILDLIFE INVESTMENTS WHILST EMBRACING WILD ANIMALS CONSERVATION IN TANZANIA

Tanzania is diversifying wildlife investments. The Special Wildlife Investment Concession Area, (the SWICA) is set aside. The regulations to achieve the purpose are in place.The regulations enlighten on the procedures of carrying out investments within the SWICA. This paper reviewson this new investment schemewhether itwill spare the ecosystem, specifically, the safety and survival of wild animals.The invited investments activities connote disturbance on the lives of wild animals. This paper observes that, the cumulative promulgation of the regulations threatens the life of wild animals. The apprehension of ecosystem disturbances in the SWICA is too wide to connote probable security on the lives of wild animals. Moreover, the avenues for some actors to excises their wisdom, aside of the regulations may invite unnecessary difficulties between the investors and the authority. Lastly, wild animals are likely to suffer a significant prejudice if investments in the SWICAs get through.

Investigation of the Relationship between Genetic and Breeding Characteristics of WBPH Behavior according to Resistant Materials in Rice.

Rice accounts for most of the calories consumed by the world's population. However, the whitebacked planthopper (WBPH), Sogatella furcifera (Horvath), is an insect that can cause rice yield loss. WBPH sucks the stems of rice and negatively affects yield and grain quality. Therefore, numerous insecticides have been developed to control WBPH in rice fields. However, chemical pesticides cause serious problems such as environmental pollution and ecosystem disturbance. Here, we research the possibility of using previously reported rice extracts obtained using methanol, Chrysoeriol 7(C7) and Cochlioquinone-9 (cq-9), as potential insect repellents. WBPH was caged with C7 or cq-9 and monitored, and the WBPH behavior was recorded. The number of WBPHs approaching the periphery of the C7 and cq-9 was very low. In cages containing the C7 and cq-9, only 13 and 7 WBPHs out of 100, respectively, walked around the material. In addition, foliar spraying with C7 and cq-9 did not negatively affect the plant height. The expression level of genes related to resistance was maintained at a high level in the resistant lines when treated with WBPHs alone, but was at a similar level to those of the controls when treated with C7 or cq-9. Interfering with WBPH access did not adversely affect the plant phenotype. Recently, people's interest in the environment has increased, and the use of plant-derived materials is also increasing. There is a new trend towards using plant extracts as an environmentally friendly means of managing resistance to WBPH during the rice cultivation period, while also avoiding environmental pollution.

Density, structure, growth, and mortality of the population of Ocypode gaudichaudii H. Milne Edwards & Lucas, 1843 (Brachyura, Ocypodidae) in Salaverry, Peru

Abstract The northern coast of Peru includes a series of dissipative desert beaches with varying levels of human impact. One endemic species to these beaches is Ocypode gaudichaudii, which has been shown to be an indicator of ecosystem disturbance. We measured population density, sex ratio, and cephalothorax length of O. gaudichaudii on three beaches near Salaverry between September 2021 and February 2022. The average population density was 0.15 burrows/m2. There was a higher proportion of males (56%); and average cephalothorax length was 28.8 ± 5.6 mm. Population, length, and sex variations during the study may be explained by behaviour of O. gaudichaudii and by temperature-dependent breeding. We also calculated the Von Bertalanffy growth parameters (, , ) and estimated the instantaneous mortality rate to be 0.84/year. These data indicate a high level of disturbance in the ecosystem, with few specimens approaching .

Artificial sound impact could put at risk hermit crabs and their symbiont anemones

The sea anemone Calliactis parasitica, which is found in the East Atlantic (Portugal to Senegal) and the Mediterranean Sea, forms a symbiotic relationship with the red hermit crab, Dardanus calidus, in which the anemone provides protection from predators such as the octopus while it gains mobility, and possibly food scraps, from the hermit crab. Acoustic pollution is recognised by the scientific community as a growing threat to ocean inhabitants. Recent findings on marine invertebrates showed that exposure to artificial sound had direct behavioural, physiological and ultrastructural consequences. In this study we assess the impact of artificial sound (received level 157 ± 5 dB re 1 μPa2 with peak levels up to 175 dB re 1 μPa2) on the red hermit crab and its symbiotic sea anemone. Scanning electron microscopy analyses revealed lesions in the statocyst of the red hermit crab and in the tentacle sensory epithelia of its anemone when exposed to low-intensity, low-frequency sounds. These ultrastructural changes under situations of acoustic stress in symbiotic partners belonging to different phyla is a new issue that may limit their survival capacity, and a new challenge in assessing the effects of acoustic disturbance in the oceanic ecosystem. Despite the lesions found in the red hermit crab, its righting reflex time was not as strongly affected showing only an increase in the range of righting times. Given that low-frequency sound levels in the ocean are increasing and that reliable bioacoustic data on invertebrates is very scarce, in light of the results of the present study, we argue that anthropogenic sound effects on invertebrates species may have direct consequences in the entire ecosystem.

Modeling global indices for estimating non-photosynthetic vegetation cover

Non-photosynthetic vegetation (NPV) includes plant litter, senesced leaves, and crop residues. NPV plays an essential role in terrestrial ecosystem processes, and is an important indicator of drought severity, ecosystem disturbance, agricultural resilience, and wildfire danger. Current moderate spatial resolution multispectral satellite systems (e.g., Landsat and Sentinel-2) have only a single band in the 2000–2500 nm shortwave infrared “SWIR2” range where non-pigment biochemical constituents of NPV, including cellulose and lignin, have important spectral absorption features. Thus, these current systems have suboptimal capabilities for characterizing NPV cover. This research used simulated spectral mixtures accounting for variability among NPV and soils to evaluate globally-appropriate hyperspectral and multispectral indices for estimation of fractional NPV cover. The Continuum Interpolated NPV Depth Index (CINDI), a weighted ratio index measuring lignocellulose absorption near 2100 nm, was found to produce the lowest error in estimating NPV cover. CINDI was less sensitive to variability in soil spectra and green vegetation cover than competing indices. While CINDI was sensitive to the relative water content of soil and NPV, this sensitivity allowed for correcting error in estimated NPV cover as water content increased. CINDI bands were less capable than Dual Absorption NPV Index (DANI) bands for maintaining continuity with the heritage Landsat SWIR2 band, but combining multiple CINDI bands demonstrated adequate continuity. Three SWIR2 bands with band centers at 2038, 2108, and 2211 nm can provide superior capabilities for future moderate resolution multispectral/superspectral systems targeting NPV monitoring, including the next generation Landsat mission (Landsat Next). These bands and the associated CINDI index provide potential for global NPV monitoring using a constellation of future superspectral sensors and imaging spectrometers, with applications including improving soil management, preventing land degradation, evaluating impacts of drought, mapping ecosystem disturbance, and assessing wildfire danger.

Spatial and temporal variation of NDVI and its driving factors based on geographical detector: A case study of Guanzhong plain urban agglomeration

Vegetation is an important component of the ecosystem cycle, which is influenced by a combination of natural and human factors, making it challenging to identify the extent of the contribution of its drivers. As one of the nine largest urban agglomerations in China, the Guanzhong Plain urban agglomeration (GPUA) has a fragile ecosystem and severe human disturbance. We concentrated on GPUA as the research object, which used a Geographical Detector to quantify the degree influence of natural and anthropogenic factors on Normalized Difference Vegetation Index (NDVI). The results are as follow, The NDVI showed an increasing trend with an annual growth rate of 0.0088/year. The variation of NDVI showed an obvious spatial pattern. The area of NDVI increased significantly in the southern region, while the significant degradation area was distributed in the northern and central parts. Natural factors contribute more to NDVI change than anthropogenic factors, with precipitation (19.5%), soil type (17.2%) and landform type (16.1%) making the greatest contributions. It was found that the effect of the two-two factor interaction on NDVI was higher than the single factor effect. The research results can effectively identify the variation characteristics of NDVI in ecologically fragile areas under the complex driving mechanism.

Prescribed Burning Alters Insects and Wood Decay in a Sagebrush-Steppe Rangeland in Southwestern Idaho, United States

Prescribed fall burning is commonly used worldwide on rangeland sites to enhance vegetation resources and restore disturbed ecosystems, but little is known about how it may alter microbial communities and insect activities. We used two site treatments (low- to moderate-burn severity plots and unburned control plots) at a high-elevation (2 100 m above sea level) shrub-steppe rangeland site. Four yr after the prescribed burn, captured insects primarily consisted of Coleoptera (beetles), Hymenoptera (ants, bees, and wasps), and Orthoptera (grasshoppers and crickets) species with similar or greater numbers captured on burned plots as compared with unburned plots. We used wood stakes to assess microbial population changes. Aspen (Populus tremuloides Michx.) and pine (Pinus taeda L.) wood stakes were placed horizontally on the soil surface and vertically into the mineral to determine microbially altered wood decay rates. In mineral soil, mass loss (wood decay) of both aspen and pine increased significantly in the burned plots after 5 yr. Surface aspen also had increased decay in the burned plots, but pine surface stakes were unaffected. Surprisingly, at this high-elevation site we also found subterranean termites (Reticulitermes tibialis Banks) feeding on both stake species, with greater numbers on aspen stakes in burned plots leading to greater wood mass loss and organic matter turnover rates. Our results suggest that that fall prescribed burning can enhance insect numbers and microbial decay in sagebrush-steppe ecosystems. Understanding these changes can help land managers predict the influence of fall prescribed burning operations on soil biological properties and insect communities.

Relationship of nematodes in natural and disturbed land with physicochemical properties in Magoebaskloof, Limpopo Province, South Africa

AbstractMagoebaskloof is an evergreen mountainous landscape covered with Afromontane forests. During a survey on soil nematode diversity, the soil samples were collected from the rhizosphere of a forest tree (no cultivation over 50 years), grassland, prepared kiwi land, oak tree, kiwifruits trees (37-year-old), and 8-year-old kiwifruit in the Limpopo Province, South Africa. Overall, results showed that a total of 30 nematode genera were found to be associated with the surveyed plant species. The frequency of occurrence showed Ditylenchus (100%), Acrobeloides (100%), and Nanidorus (100%), followed by Meloidogyne (83%) were the most distributed nematodes. The study of the relationship between nematodes with physicochemical properties in the soil using Pearson correlation revealed that clay percentage of the soil has a positive correlation with Pseudacrobeles (r = 0.684), Acrobeloides (r = 0.658) and Meloidogyne (r = 0.668) species. In contrast, clay percentage had a strong negative correlation (r = -0.900) with Filenchus. Soil pH showed no strong correlation with the nematodes. The principal component analysis placed kiwifruits and forest soil in two groups, indicating the biodiversity dynamics among the two locations. In conclusion, forest trees and grasslands showed a high diversity of free-living than disturbed land of kiwifruits. Additionally, plant-parasitic nematodes numbered more in the rhizosphere of kiwifruit trees. Our results suggest that the soil nematodes, especially free-living bacterivores, may mediate the effects of ecosystem disturbance on soil health.