Effects Of Anthropogenic Disturbance Research Articles

The role of chronic anthropogenic disturbances in plant community assembly along a water availability gradient in Brazil’s semiarid Caatinga region

The effects of anthropogenic disturbances on the structure and function of seasonally dry tropical forests (SDTFs) are mediated both by disturbance type and intensity, and the environmental conditions, including climate. In a climate change scenario, the interaction between low water availability and chronic anthropogenic disturbances may potentially have drastic consequences on SDTF dynamics and the ecosystem services it provides. We hypothesized that in these naturally stressed systems, the effects of human disturbance are strongest in the most water-stressed sites, implying a worrisome synergism between harsh abiotic conditions (lower precipitation, higher temperature) and human effects, ultimately resulting in a less developed community structure and reduced diversity. By integrating information for the adult and regenerating vegetation strata in 21 sites distributed across climatic, plant cover and disturbance gradients in the Caatinga (seasonally dry tropical) forest of Brazil, we analyzed the individual and combined effects of chronic anthropogenic disturbances, as measured through the Cattle Pressure Index and the Human Activity Index, along climate gradients, on community structure, diversity, and composition. As expected, the Cattle Pressure Index was negatively related to diameter at ground level, basal area, and diversity in the adult stratum, whereas for the regenerating stratum, litter stock had the strongest effect on vegetation structure. Climatic factors were poor predictors of the variation in the three true diversity measures (0D, 1D, and 2D) of the regenerating community. Our results revealed important cross-site differences in both vegetation strata over a small range of climatic variation. We conclude that the most stressful conditions associated with a very low precipitation regime enhance the effects on chronic disturbances, gradually driving SDTF communities into new alternative states and rendering these environments more prone to desertification.

Short-Term Effects of Anthropogenic Disturbances on Stand Structure, Soil Properties, and Vegetation Diversity in a Former Virgin Mixed Forest

Despite the sharply growing interest in the disturbances occurring in primary forests, little is known about the response of European virgin forests to anthropogenic disturbance. The present study investigated the effect of the first silvicultural interventions that took place nine years earlier in a former virgin forest (FVF). Changes in the stand structure, environmental characteristics, and diversity of ground vegetation were studied in comparison with a nearby virgin forest (VF), both consisting of a mixture of European beech and silver fir. While the tree density did not differ significantly between the two forests, the number of large trees, the basal area, and the stand volume were significantly reduced in the FVF. The deadwood volume was twice as great in the VF as in the FVF and was found in both forests, particularly from silver fir. Despite significantly better light conditions in the FVF, natural regeneration was not significantly higher than in the VF. However, a slight improvement in the proportion of silver fir and other tree species into total regeneration was reported. The soil temperature was significantly higher in the FVF, independent of the measurement season, while the soil moisture showed a higher value in the VF only in spring. The FVF is characterized by a greater soil CO2 emission, which is especially significant in summer and fall. The diversity of the ground vegetation did not yet react significantly to the silvicultural intervention. These preliminary findings are important in drawing suitable forest management practices that need to be applied in mixed beech–silver fir stands, especially in terms of maintaining species diversity. However, the short time frame since the intervention obliges further research on this VF–FVF pair over the next 10–20 years, at least regarding silver fir dynamics.

Legacy effects of anthropogenic disturbances modulate dynamics in the world's coral reefs.

Rapidly changing conditions alter disturbance patterns, highlighting the need to better understand how the transition from pulse disturbances to more persistent stress will impact ecosystem dynamics. We conducted a global analysis of the impacts of 11 types of disturbances on reef integrity using the rate of change of coral cover as a measure of damage. Then, we evaluated how the magnitude of the damage due to thermal stress, cyclones, and diseases varied among tropical Atlantic and Indo-Pacific reefs and whether the cumulative impact of thermal stress and cyclones was able to modulate the responses of reefs to future events. We found that reef damage largely depends on the condition of a reef before a disturbance, disturbance intensity, and biogeographic region, regardless of the type of disturbance. Changes in coral cover after thermal stress events were largely influenced by the cumulative stress of past disturbances and did not depend on disturbance intensity or initial coral cover, which suggests that an ecological memory is present within coral communities. In contrast, the effect of cyclones (and likely other physical impacts) was primarily modulated by the initial reef condition and did not appear to be influenced by previous impacts. Our findings also underscore that coral reefs can recover if stressful conditions decrease, yet the lack of action to reduce anthropogenic impacts and greenhouse gas emissions continues to trigger reef degradation. We uphold that evidence-based strategies can guide managers to make better decisions to prepare for future disturbances.

Analysis of the correlation between genetic and species diversity in a temperate forest: Variation in cohorts and effect of disturbance

Species diversity and genetic diversity are related through three possible predictions: the parallel action of eco-evolutionary processes on the two diversity components; the influence of genetic diversity on species diversity; or vice versa. Environmental factors affect these relationships because they affect population size and migration. Since environmental changes have a late effect on genetic diversity in long-lived species, this study analyzed the relationship between species diversity and genetic diversity of two cohorts of Abies religiosa and Pinus montezumae in temperate forest tree assemblages and explored the effect of anthropogenic disturbance on this relationship. We expected to find positive correlations and an effect of species diversity on genetic diversity, relationships that become more intense under anthropogenic disturbance and in seedling populations. Twelve assemblages with evident deforestation were identified in La Malinche National Park; in each assemblage, disturbance was measured by the percentage of forest cover and the Disturbance Impact Factor. We estimated additive diversity and species turnover between pairs of assemblages while genetic diversity, differentiation, and distances were derived based on single-nucleotide polymorphisms. To test the first prediction, Spearman's correlations between species diversity and genetic diversity were performed, while the second and third predictions were assessed by constructing General Linear Models (GLMs). The influence of disturbance was evaluated using partial correlations and GLMs. In both species, positive correlations were identified that varied between cohorts, and disturbance had an interactive and additive influence on these relationships. In P. montezumae seedlings, species diversity affected genetic diversity, while we observed the opposite effect in adults. Furthermore, the genetic differentiation of A. religiosa seedlings was associated with environmental distances. Controlling land-use changes in temperate forests is a top priority for conserving species diversity and safeguarding genetic diversity and ecosystem functioning. This research contributes to understanding the eco-evolutionary processes that govern tree assemblages of temperate forests.

Effects of anthropogenic disturbances on diaspore removal by ants: A meta-analysis

Anthropogenic changes in natural landscapes are identified as a major driver of biodiversity loss worldwide. Consequently, important ecosystem functions, such as seed dispersal by animals, can be lost, which threaten the stability of essential ecological processes. Given the current scenario of large seed disperser's loss, secondary dispersal by ants has been identified as an important alternative to mitigate the impacts caused by human changes. However, empirical evidence shows contradictory effects of anthropogenic disturbances on diaspore removal by ants. Here, we conducted a global meta-analysis from 22 studies (65 comparisons) comparing diaspore removal by ants in disturbed versus preserved areas to investigate general trends to different anthropogenic disturbances. Specifically, we evaluate: (i) the effects of anthropogenic disturbances on diaspore removal by ants comparing temperate and tropical regions, and (ii) comparing different disturbance types (agriculture related disturbances, fragmentation, mining, fire, etc.) on diaspore removal by ants. We found an overall negative effect of anthropogenic disturbances on diaspore removal by ants (26% decrease), both in temperate and tropical regions (38% and 19% decrease, respectively). In addition, diaspore removal by ants responded negatively to disturbances related to fragmentation (24% decrease) and mining (83% decrease). However, we found no evidence of effects in areas subjected to agricultural processes (0.9% decrease). Our findings suggest that human disturbances might compromise crucial early stages to the natural regeneration in ecosystems such the seed dispersal.

The influence of forest harvesting activities on seismic line tree and shrub regeneration in upland mixedwood boreal forests

Alberta's forests are becoming increasingly disturbed and fragmented by the cumulative effects of anthropogenic disturbances exacerbated by the enduring footprint of seismic lines on the landscape. Forest harvesting and subsequent reforestation activities (e.g., site preparation and tree planting) may facilitate tree growth on seismic lines when forestry companies incorporate them into management areas. In this study, forest regeneration was assessed along transects on and off seismic lines within four cutblocks in northwestern Alberta. Tree, sapling, and shrub characteristics were measured, and tree cookies from a subset of trees on and off seismic lines were used to model height growth. No difference in total tree, sapling, or shrub counts on and off seismic lines was found although trees on seismic lines were growing at slightly slower rates compared to the adjacent cutblock, and Alnus viridis was more abundant on seismic lines. Our results suggest that, despite some species-level differences and modest differences in tree growth rates, trees on seismic lines within cutblocks are regenerating similarly to other trees growing in the post-harvest stand. These findings indicate that forest harvesting, and subsequent reforestation, could represent an important tool in conducting landscape-level restoration in mixedwood forests where seismic lines have not naturally recovered.

Exploring the effects of anthropogenic disturbance on predator inspection activity in Trinidadian guppies.

Exploring the effects of anthropogenic disturbance on predator inspection activity in Trinidadian guppies.

Seasonal community stability increased with water addition and shrub removal but reduced with nitrogen addition in semi‐arid grassland

Abstract Stability is a useful indicator of the functioning and sustainability of an ecosystem, and much studies have explored the effects of anthropogenic disturbance on the inter‐annual stability of plant community. However, the effects of multiple anthropogenic stressors on seasonal community stability have not been clearly elucidated, especially for vulnerable semi‐arid grasslands. During the growing season in the 5th year of the experiment, we determined how nitrogen (N) addition, water addition and shrub removal altered seasonal community stability in a semi‐arid grassland dominated by the shrub Caragana microphylla on the Mongolian Plateau. We found that shrub removal, N addition and water addition had different effects on the stability of community and plant functional groups (PFGs). Shrub removal increased seasonal community stability mostly via increases in the stability of perennial forbs and C4 plants, and shrub removal did not alter the effects of N addition or water addition on seasonal community stability or PFG stability. N addition decreased seasonal community stability mostly via decreases in the stability of perennial rhizome grasses and C4 plants. Water addition increased seasonal community stability mostly via increases in the stability of annuals and biennials, perennial forbs, perennial rhizome grasses, dominant species and C4 plants. Species asynchrony and PFG stability but not species richness or soil abiotic or biotic variables helped to maintain seasonal community stability under N addition or water addition. Our findings indicate that future scenarios of increases in N deposition and shrub encroachment will strongly reduce community stability in drylands, and that future scenarios of increases in precipitation together with shrub removal might help to maintain the stability of this and other dryland ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

Exploring ant diversity with fuzzy logic and python

Fuzzy logic can be used to identify patterns in the data, which can be used to better understand the diversity of a particular ecosystem. This study examines the diversity of ants in different sites of Palayamkottai using the Combined Effect Quantity Dependent Data Matrix (CEQD-Matrix). Initial raw data is collected and transformed into an Average Quantity Dependent Data matrix (AQD Matrix) by taking ants' names as rows and point count sites as columns. A defined quantity dependent data matrix (RQD Matrix) is then generated using mean and standard deviation methods. Finally, a Combined Effect Quantity Dependent Data matrix (CEQD Matrix) is produced to show the cumulative effect of all the entries. Python is used to generate the graphs of the RQD Matrix and CEQD Matrix. It was found that the species Tetraponera rufonigra predominantly occupied the all sites, followed by Oecophylla smaragdina. The matrix was also used to predict the effects of anthropogenic disturbances on the ant diversity.

Soil disturbance impacts on ant‐diaspore multilayer networks in a tropical savanna

Abstract1. Current anthropogenic disturbances have changed natural environments, broadly impacting ecosystem services and functions. Here, the authors focused on the secondary dispersal of diaspores by ants, which serve an important ecological function in the natural regeneration of degraded habitats.2. The authors experimentally studied the effects of vegetation suppression and soil disturbance on (i) diaspore removal, (ii) the quality of secondary removal, and (iii) the structure of interaction networks between ants and diaspores. The authors tested whether the disturbance affected the species richness of seed removers, diaspore removal rate, removal distance and time, and removal effectiveness. Additionally, the authors tested whether the structure of ant‐diaspore networks, that is, specialisation, modularity and robustness, is altered by soil disturbance. To do that, the authors studied three degraded and three preserved areas in the Brazilian Cerrado.3. The authors observed 25 ant species interacting with the diaspores. Disturbance did not affect ant species richness, removal distance or removal rate, but ants took twice as long to remove the diaspores in the preserved habitat. The frequency of interaction networks was higher in the preserved habitat, and the effectiveness of species in removing the diaspores differed between habitats. Surprisingly, the authors observed that ants considered effective dispersers mostly occurred in degraded habitats, highlighting the potential of myrmecochory in the regeneration of impacted environments.4. The findings point to the potential of ants in acting as secondary seed dispersal, improving the restoration of areas highly impacted by soil disturbance. Moreover, this study contributes to understanding the effects of anthropogenic disturbances on ecological interactions and ecosystem functions.

Effects of anthropogenic disturbance on group densities of Thomas' langurs (Presbytis thomasi) within a lowland tropical forest, north Sumatra

AbstractEcosystems around the globe are facing irreversible impacts due to climate change, habitat destruction, hunting, and an ever‐increasing human population. Estimating densities of species across their geographical range helps us to understand natural variation and anthropogenic effects on species densities and to assess the effectiveness of existing conservation measures. Various methods have been used to produce accurate and precise population density estimates, each with associated limitations. Acoustic surveys for species producing loud calls have become common due to their ease of use, low cost, and reduced timescale. Relative to many other mammal taxa, primate species have been studied extensively, producing a wealth of data on socioecology and behavior, but for most species, density estimates over large geographical ranges are still lacking. We used an acoustic spatial capture–recapture model to estimate group density of unhabituated Thomas' langurs (Presbytis thomasi), a primate endemic to the Indonesian island of Sumatra, over a 60 km2 area of lowland dipterocarp forest. We then assessed if vegetation structure and distance from human habitation affected density estimates. Estimates of group density differed almost threefold between survey locations (from 2.79 to 8.08 groups/km2); there was no clear relationship with forest structure, but there was a significantly positive relationship between group density and distance from human habitation, with an increase of 0.38 groups/km2 for every km of distance. Although large‐scale logging within the Sikundur region ceased ~30 years ago, the impacts of logging continue to have detrimental effects on the species within the area.

Diverse data sources and new statistical models offer prospects for improving the predictability of anthropogenic hybridization.

Human disturbance can theoretically influence the rates of hybridization, but few studies have convincingly identified a causal link. Grabenstein et al. (2022) used a genomic and phenotypic study of chickadees to associate hybridization with human disturbance. Additionally, this is consistent with citizen science reports of chickadee hybrids across the range. We highlight the exciting aspects of this work and make suggestions about a role for broad geographic and genomic sampling, and new statistical methods to better connect hybridization outcomes to anthropogenic disturbance in diverse study systems.

Disentangling vertebrate spatio-temporal responses to anthropogenic disturbances: evidence from a protected area in central Myanmar

AbstractUrbanization of natural landscapes and increasing human populations have brought people and our companion animals into closer contact with wildlife, even within protected areas. To provide guidance for human–wildlife coexistence, it is therefore critical to understand the effects of anthropogenic disturbances and how well native wildlife species survive in human-dominated landscapes. We investigated the spatio-temporal responses of 10 vertebrate taxa, with an emphasis on the Endangered Eld's deer Rucervus eldii thamin, to anthropogenic disturbances in Shwesettaw Wildlife Sanctuary, Myanmar. We quantified anthropogenic disturbances as distance from human settlements, distance from a highway, and the presence of people and free-ranging dogs Canis familiaris. Anthropogenic disturbances had stronger negative impacts on the detection of native wildlife species than on occupancy. Eld's deer avoided areas close to human settlements and showed low diel activity overlap with both people and dogs, although we found a positive association with human presence at the camera-trap sites. Five species exhibited lower diel activity overlap with people in the rainy season when human activity is the highest in our study area. All studied wildlife species shifted to nocturnal activity or did not show any clear activity pattern during the cool-dry season when the presence of dogs increased. The ecological and conservation impacts of dogs are underestimated in South-east Asia, particularly in Myanmar, and this case study highlights the impacts of dogs on the temporal use of habitat by wildlife and the need for better practices in the management of dogs within protected areas.

Body Condition and Allometry of Free-Ranging Short-Finned Pilot Whales in the North Atlantic

To understand the effects of anthropogenic disturbance on the nutritional health of animals, it is important to measure and understand the morphometrics, allometrics, and body condition of the species. We examined the body shape, allometric relationships, and body condition of short-finned pilot whales (Globicephala macrorhynchus) in three locations across the North Atlantic. Using unmanned aerial vehicles, the body length (BL) and width (along the body axis) were measured from photographs of the dorsal side, while body height (dorso-ventral distance) was measured on the lateral side. Seventy-seven pilot whales were measured (mean ± SD), including 9 calves (BL 2.37 m ± 0.118), 31 juveniles (2.90 m ± 0.183), and 37 adults (3.72 m ± 0.440). The body shape was similar among reproductive classes, with the widest point being anterior of the dorsal fin (at 30–35% BL from the rostrum). The cross-sectional body shape of the whales was flattened in the lateral plane, which increased towards the peduncle and fluke. The rostrum-blowhole distance and fluke width increased linearly with BL. The estimated volumes of pilot whales ranged between 0.15 and 0.32 m3 for calves, 0.25 and 0.64 m3 for juveniles, and 0.46 and 1.13 m3 for adults. The body condition (residual of log-volume vs. log-length) ranged from −34.8 to +52.4%. There was no difference in body condition among reproductive classes or locations.

Detection of community-wide impacts of bottom trawl fishing on deep-sea assemblages using environmental DNA metabarcoding.

Although considerable research progress on the effects of anthropogenic disturbance in the deep sea has been made in recent years, our understanding of these impacts at community level remains limited. Here, we studied deep-sea assemblages of Sicily (Mediterranean Sea) subject to different intensities of benthic trawling using environmental DNA (eDNA) metabarcoding and taxonomic identification of meiofauna communities. Firstly, eDNA metabarcoding data did not detect trawling impacts using alpha diversity whereas meiofauna data detected a significant effect of trawling. Secondly, both eDNA and meiofauna data detected significantly different communities across distinct levels of trawling intensity when we examined beta diversity. Taxonomic assignment of the eDNA data revealed that Bryozoa was present only at untrawled sites, highlighting their vulnerability to trawling. Our results provide evidence for community-wide impacts of trawling, with different trawling intensities leading to distinct deep-sea communities. Finally, we highlight the need for further studies to unravel understudied deep-sea biodiversity.

Comparison of taxonomic and size-based approaches to determine the effects of environment and disturbance on invertebrate communities in coastal Chile

• Disturbance from land use change and tsunamis impact Chilean invertebrates. • Aquatic and terrestrial communities respond differently to wetland disturbance. • Coastal wetland invertebrate communities vary with latitudinal gradients. • Disturbance impacts on size vary according to salinity. • Taxonomic diversity and size-based metrics detect different disturbance impacts. The frequency and intensity of extreme events in coastal wetlands is increasing due to climate change. These, in combination with other threats such as habitat loss, can have strong effects on the biodiversity and ecosystem services of coastal wetland ecosystems. Here we examined how traditional (community composition and taxonomic diversity) and alternative indices based on body size (size diversity and the slope of size spectra) respond to single and combined effects of anthropogenic disturbances, extreme event disturbances, and key environmental drivers, for both aquatic and terrestrial invertebrates in Mediterranean coastal wetlands in Chile. We studied 18 coastal wetlands over more than 500 km along the Chilean coast. We applied both univariate (GLMMs and GAMMs) and multivariate statistics (RDA and variation partitioning) to identify additive and non-additive effects on invertebrates. We also examined latitudinal trends, and tested the potential of alternative metrics to detect interactions between disturbances. We found latitude-specific vulnerability to disturbances in Chilean coastal wetlands. Non-additive effects were more important for aquatic invertebrates, while additive effects were more important for terrestrial invertebrates. In many cases, disturbance effects depended on the environmental conditions of study sites, especially salinity. This study suggests that size-based metrics may be better than taxonomic metrics at detecting interactions among different disturbances, especially for aquatic invertebrates.

Habitat loss increases seasonal interaction rewiring in plant–pollinator networks

Abstract Understanding the flexibility of interactions and network rewiring (i.e. reassembly of interactions due to partner‐switching) is necessary to comprehend how future anthropogenic changes will affect interspecific interactions and the functioning of communities. A higher rewiring could be expected in more disturbed landscapes because these landscapes contain fewer and more generalist species with more homogeneous traits. We sampled pollination interactions in 20 wild Olea europaea communities along a disturbance gradient to evaluate the hypothesis that the loss of natural habitats increases seasonal (within‐year) interaction rewiring in plant‐pollinator communities, influencing their functional structure. For this, we particularly tested whether rewiring frequency was negatively related to the extent of natural habitats surrounding the communities, whether interaction rewiring influenced the static structure of networks (nestedness, network specialization –H2'–), and whether a high generalization (low specialization –d'–) and abundance of species in communities made them more prone to rewiring. We show that habitat loss increased seasonal interaction rewiring in networks. Changes in rewiring were related to changes in the cumulative static structure of pollination networks. Nestedness decreased and network specialization (H2') also tended to decrease as interaction rewiring increased, suggesting an indirect effect of habitat loss on the robustness of networks through their dynamics. As expected, generalist insect and plant species were more prone to rewiring. However, flower abundance had different effects on the rewiring probability of plant species depending on the extent of habitat loss, with abundant species rewiring more in disturbed communities and rewiring less in more natural communities. Likely, this is related to the context‐dependent foraging behaviour of pollinators, which may switch to more abundant species if the cost of searching for trait‐matching resources is high in disturbed habitats. Our work shows the role of partner‐switching in generalist species to adapt to new conditions. It also highlights the importance of going beyond general network metrics to understand the underlying processes of community‐level interaction assembly and predict and anticipate the effects of anthropogenic disturbances on pollination services. Read the free Plain Language Summary for this article on the Journal blog.

Anthropogenic degradation alter surface soil biogeochemical pools and microbial communities in an Andean temperate forest

Soil microbial communities regulate a myriad of critical biogeochemical functions in forest ecosystems. Anthropogenic disturbances in natural forests could drive major shifts in plant and microbial communities resulting in substantial biogeochemical alterations. We evaluated the effect of anthropogenic disturbances in the soils of Andean temperate forests with different levels of degradation: i) mature forest (MF), ii) secondary forest (SF), iii) degraded forest (DF), and iv) deforested site converted into a prairie (DP). We quantified total soil carbon, nitrogen and phosphorous (TC, TN, and TP), and available nutrient stocks. The soil microbial community structure (i.e., composition, diversity, and abundance) was assessed under each condition from amplicon sequence variants (ASVs) obtained via NGS-Illumina sequencing and subsequent microbiome analysis. There were no significant differences in TC, TN, and TP across the forested states (MF, SF, DF). The deforested site condition presented significantly higher soil TC, TN, and TP and the lowest C:N, C:P, and N:P ratios. The DP soil microbiome was significantly more diverse in bacteria (D′ = 0.47 ± 0.04); and fungi (H′ = 5.11 ± 0.33). The bacterial microbiome was dominated by Proteobacteria (45.35 ± 0.89 %), Acidobacteria (20.73 ± 1.48 %), Actinobacteria (12.59 ± 0.34 %), and Bacteroidetes (7.32 ± 0.36 %) phyla in all sites. The soil fungal community was dominated by the phyla Ascomycota (42.11 ± 0.95 %), Mortierellomycota (28.74 ± 2.25 %), Basidiomycota (24.61 ± 0.52), and Mucoromycota (2.06 ± 0.43 %). Yet, there were significant differences at the genus level across conditions. Forest to prairie conversion facilitated the introduction of exotic bacterial and fungal taxa associated with agricultural activities and livestock grazing (∼50 % of DP core microbiome composed of unique ASVs). For example, the ammonia-oxidizing bacteria community emerged as a dominant group in the DP soils, along with a reduction in the ectomycorrhizal fungi community. The surface soil microbial community was surprisingly resistant to forest degradation and did not show a clear succession along the degradation gradient, but it was strongly altered after deforestation.

Habitat Quality Assessment and Ecological Risks Prediction: An Analysis in the Beijing-Hangzhou Grand Canal (Suzhou Section)

With the fast pace of global urbanization, anthropogenic disturbances not only lead to frequent disasters, but also cause direct and indirect ecological and economic losses. To reduce the adverse effects of anthropogenic disturbances as part of sustainable ecosystem management, assessments of habitat quality and ecological risk are necessary. The objectives of this study are to analyze environmental conditions of the Beijing-Hangzhou Grand Canal (Suzhou section) for evaluating habitat quality and habitat degradation, and to conduct ecological-risk early warning assessment in this section. The Grand Canal is the longest and first canal in the world to be artificially excavated from natural rivers and lakes. By evaluating habitat quality using the InVEST suite of open-source software models for mapping and valuing the ecosystem, it was found that the natural lands with high habitat quality such as wetlands, forests and lakes along the Suzhou section of the Grand Canal have gradually decreased, while construction lands such as roads and buildings have gradually increased; there is a clear trend of decreasing areas with high habitat quality and increasing areas with low habitat quality, which is likely the result of urbanization. It was also found that the region has a high habitat degradation index, meaning that areas located at the junction of different land types are vulnerable to the surrounding environment due to narrow buffer zones that allow areas with high habitat quality to be easily affected by areas with low habitat quality. In terms of ecological risks, it was found that the natural land area with high habitat quality in the downstream locations was declining, thereby increasing the risks of pollution and flooding events while reducing the ecosystem’s resilience. The valuation model used in this study can be used as an effective decision-support tool to prioritize important ecological areas for conservation in the Grand Canal, and can also be adapted for use in the ecosystem management of other regions.

Spatio-temporal Effects of Anthropogenic Disturbances on Macroinvertebrates in Subukia River, Kenya

Anthropogenic disturbances modify river habitat conditions and influence the distribution of biotic communities. However, the effect of anthropogenic disturbances on macroinvertebrates is unknown for the Subukia River, despite its importance as a source of water for the local people and a habitat for organisms. This study was conducted to evaluate the effect of study site locality and seasonal variability on macroinvertebrate characteristics in the Subukia River. Nine study sites were chosen to correspond with livestock watering and human activities such as laundry washing, water abstraction, cultivation, dumping of solid wastes, settlements along the riparian zone and clearance of riparian vegetation. Mean invertebrate abundance, Shannon-Wiener diversity index, a Multimetric index, Taxa richness, Ephemeroptera, Plecoptera, Trichoptera (EPT) abundance and richness and Dominance index were determined. The results of the study showed that study site locality had a significant effect on Taxa richness (p=0.003), EPT abundance (p = 0.003) and richness (p=0.02), Shannon-Wiener diversity (p=0.003) and Multimetric index (p=0.003). Seasonal variability only had a significant effect on Taxa richness (p=0.01). In conclusion, most macroinvertebrate characteristics are influenced by anthropogenic disturbances and are less influenced by seasonal variability.