Types Of Anthropogenic Disturbances Research Articles

Different responses of taxonomic and functional structures of stream macroinvertebrate communities to local stressors and regional factors in a subtropical biodiversity hotspot

Examining the relative contribution of local environmental stressors and regional factors in structuring biological communities is essential for biodiversity conservation and environmental assessment, yet their relative roles for different community characterizations remain elusive. Here, we examined the responses of taxonomic and functional structures of stream macroinvertebrate communities to local and regional factors across a human-induced environmental gradient in the Han River Basin, one subtropical biodiversity hotspot in China. Our objectives were: 1) to examine the responses of traditional taxonomic measures and functional traits to anthropogenic disturbances; 2) to compare the relative importance of environmental versus spatial variables and catchment-scale versus reach-scale variables for the two community characterizations. We found that both species and trait compositions performed well in differentiating anthropogenic disturbances, indicating that both taxonomic and functional structures of macroinvertebrate communities were strongly altered by human activities. Particularly, some traits related to life history (e.g., voltinism), resilience and resistance (e.g., adult flying ability) are well suited for predicting changes of communities towards anthropogenic disturbances owing to their mechanistic relationship with environmental gradients. We found that environmental variables played more important roles than spatial effects in structuring both taxonomic and functional facets of macroinvertebrate communities. Environmental filtering was more important in determining functional than taxonomic structure, and the opposite was true for spatial effects. In terms of environmental variables, catchment land-uses played the primary role in determining taxonomic composition, whereas reach-scale variables related to local habitat heterogeneity were more influential for functional structure. Our study highlights the importance of employing metacommunity perspectives and different community characterizations in both theoretical and applied research. For stream bioassessment and management, we argue that the combination of taxonomic and functional characterizations of community should be implemented, as different facets of biological communities responded to different types of anthropogenic disturbances.

Differences between primary and secondary plant succession among biomes of the world

Abstract Successional theory lacks an explicit, conceptual integration across types of disturbances and biomes. Most successional research addresses site‐ or process‐specific questions, but extrapolation of the findings to broad scales is limited. Studies of plant succession are often distinguished by the severity of the disturbance that triggers them (severely disturbed: primary; less severely disturbed: secondary). Here, we examine the common assumption that primary and secondary succession differ. We use two anthropogenic disturbances for this comparison, mining and ploughing. Successional generalizations are confounded by a complexity of environmental factors including climatic and geographic variation. We address these issues by contrasting succession across multiple biomes. We selected 166 studies of succession on mining sites (n = 73) or abandoned fields (n = 93) that allowed us to compare successional trajectories in terms of the likelihood of a return to target vegetation, changes in species richness, type of trajectories, and the importance of alien species. Success of both types of succession (a return to target vegetation) differed significantly among biomes, with more likely success in cold than warm biomes (for both primary and secondary seres) and in humid than arid biomes (primary seres only). Primary seres were also more likely than secondary seres to have increases in species richness, a predominance of divergent trajectories, and a lower likelihood that alien species influenced succession. Synthesis. The probability of reaching target vegetation by spontaneous succession is generally greater in biomes at higher versus lower latitudes. Primary and secondary seres differed regarding species richness, trajectories, and the role of alien species. Our results highlight that broad generalizations about succession are possible, despite a paucity of comparable data and our use of only two types of anthropogenic disturbances. Any generalizations that might be found among seres across disturbances and biomes will provide a practical framework for land managers to guide restoration efforts, particularly in poorly studied areas.

Unmanned aircraft systems as a new source of disturbance for wildlife: A systematic review.

The use of small Unmanned Aircraft Systems (UAS; also known as “drones”) for professional and personal-leisure use is increasing enormously. UAS operate at low altitudes (<500 m) and in any terrain, thus they are susceptible to interact with local fauna, generating a new type of anthropogenic disturbance that has not been systematically evaluated. To address this gap, we performed a review of the existent literature about animals’ responses to UAS flights and conducted a pooled analysis of the data to determine the probability and intensity of the disturbance, and to identify the factors influencing animals’ reactions towards the small aircraft. We found that wildlife reactions depended on both the UAS attributes (flight pattern, engine type and size of aircraft) and the characteristics of animals themselves (type of animal, life-history stage and level of aggregation). Target-oriented flight patterns, larger UAS sizes, and fuel-powered (noisier) engines evoked the strongest reactions in wildlife. Animals during the non-breeding period and in large groups were more likely to show behavioral reactions to UAS, and birds are more prone to react than other taxa. We discuss the implications of these results in the context of wildlife disturbance and suggest guidelines for conservationists, users and manufacturers to minimize the impact of UAS. In addition, we propose that the legal framework needs to be adapted so that appropriate actions can be undertaken when wildlife is negatively affected by these emergent practices.

Impact of anthropogenic disturbance on the density and activity pattern of deer evaluated with respect to spatial scale-dependency

This study examined the influence of anthropogenic disturbance (agriculture, forestry, hunting and feral domestic dogs) on the population density and daily activity pattern of deer. We quantified the effects of land use (broad-leaved forest, mixed coniferous/broad-leaved forest, natural grassland, subalpine vegetation, forestry area, and agricultural land), along with hunting pressure, and densities of feral domestic dogs and wild macaques on deer. The effects of land use were analyzed at various spatial scales and a model selection procedure (generalized mixed model) was used to examine the effects of factors on density and daily activity pattern of deer at each spatial scale. The combinations of influential factors differed between density and daily activity pattern and changed with spatial scale. The spatial scale with the smallest Akaike's Information Criterion value was defined as the effective spatial scale for each of density and daily activity pattern. Deer density was affected positively by the percentage of area covered by broad-leaved forest, natural grassland and macaque density, and negatively by percentage of area covered by agricultural land and mixed forest at the effective spatial scales. For the daily activity pattern of deer, agricultural land, forestry area, natural grassland, subalpine vegetation and dog density reduced diurnal and increased nocturnal activity. Crepuscular activity increased with hunting pressure and subalpine vegetation, and decreased with agricultural land. Thus, daily activity pattern was sensitive to more types of anthropogenic disturbance than density. Detecting the appropriate spatial scales at which significant anthropogenic disturbance should be managed is essential for effective wildlife conservation.

La diversidad floral del borde afecta la riqueza y abundancia de visitantes florales nativos en cultivos de girasol

Ecología Austral, 24:94-102 (2014)Pollinator decline has been related to different types of anthropogenic disturbances, a topic largely debated in the context of global change. Within this debate, it has been stressed the importance of natural or semi-natural habitat remnants as pollinator sources for nearby agricultural fields. The SW of Buenos Aires Province is a highly-impacted and intensively-used agricultural region. However, field margins associated with country roads can provide diverse floristic resources and nesting sites for a variety of pollinators, which can eventually improve pollination and productivity of neighboring pollinator-dependent crops. Here, we evaluated the effect of floral diversity of field margins on the richness and abundance of floral visitors across 17 sunflower lots in the districts of Balcarce and Lobería. Our results indicate that floral diversity of field margins had a positive effect on the richness and abundance of native floral visitors in the adjacent crop field. As a consequence, pollination services in these agroecosystems would be promoted by increasing the amount and diversity of these marginal habitats.

La diversidad floral del borde afecta la riqueza y abundancia de visitantes florales nativos en cultivos de girasol

Ecología Austral, 24:94-102 (2014)Pollinator decline has been related to different types of anthropogenic disturbances, a topic largely debated in the context of global change. Within this debate, it has been stressed the importance of natural or semi-natural habitat remnants as pollinator sources for nearby agricultural fields. The SW of Buenos Aires Province is a highly-impacted and intensively-used agricultural region. However, field margins associated with country roads can provide diverse floristic resources and nesting sites for a variety of pollinators, which can eventually improve pollination and productivity of neighboring pollinator-dependent crops. Here, we evaluated the effect of floral diversity of field margins on the richness and abundance of floral visitors across 17 sunflower lots in the districts of Balcarce and Lobería. Our results indicate that floral diversity of field margins had a positive effect on the richness and abundance of native floral visitors in the adjacent crop field. As a consequence, pollination services in these agroecosystems would be promoted by increasing the amount and diversity of these marginal habitats.

Does disturbance regime change community assembly of angiosperm plant communities in the boreal forest?

To examine if and how species and phylogenetic diversity change in relation to disturbance, we conducted a review of ecological literature by testing the consistency of the relationship between phylogenetic diversity and disturbance and compared taxonomic groups, type of disturbance and ecosystem/habitat context. We provide a case study of the phylogenetic diversity–disturbance relationship in angiosperm plant communities of a boreal forest region, compared with types of natural and anthropogenic disturbances and plant growth forms. Using a large-scale sampling plot network along a complete (0–100%) anthropogenic disturbance gradient in the boreal biome, we compared the changes of angiosperm plant community structure and composition across plots. We estimated natural disturbance with historical records of major fires. We then calculated phylogenetic diversity indexes and determined species richness in order to compare linear and polynomial trends along disturbance gradients. We also compared the changes of community structure for different types of anthropogenic disturbances and examined how the relationships between species and phylogenetic diversity and disturbance regimes vary among three different life forms (i.e. forbs, graminoids and woody plants). Phylogenetic diversity was inconsistently related to disturbance in previous studies, regardless of taxon, disturbance type or ecosystem context. In the understudied boreal ecosystem, angiosperm plant communities varied greatly in species richness and phylogenetic diversity along anthropogenic disturbance gradients and among different disturbance types. In general, a quadratic curve described the relationship between species richness and anthropogenic disturbance, with the highest richness at intermediate anthropogenic disturbance levels. However, phylogenetic diversity was not related to disturbance in any consistent manner and species richness was not correlated with phylogenetic diversity. Phylogenetic relatedness was also inconsistent across plant growth forms and different anthropogenic disturbance types. Unlike the inconsistent patterns observed for anthropogenic disturbance, community assembly among localities varying in time since natural disturbance exhibited a distinct signature of phylogenetic relatedness, although those trends varied among plant growth forms.

Impacts of Agricultural Drainage Outlets on Great Lakes Coastal Wetlands

Great Lakes coastal wetlands are subject to many types of anthropogenic disturbances. Agricultural non-point source pollution is a major contributor to the eutrophication of coastal aquatic systems and agricultural pesticides and herbicides have been linked to losses of wetland biodiversity. Nutrients and pollutants are washed off the landscape during rain events and often times enter drainage systems that are connected to Great Lakes waters. The purpose of this study was to assess the effect that agricultural drainage systems have on coastal wetlands and to measure the subsequent alterations in coastal wetland biota. We sampled coastal wetland sites in Lake Huron and Lake Michigan near ( 1500 m) from drainage outlets for habitat conditions, aquatic macroinvertebrates and fish. Non-metric multi-dimensional scaling (NMDS) analysis in conjunction with a multi response permutation procedure (MRPP) revealed differences in macroinvertebrate community compositions located near drainage outlets when compared to sites far from outlets. Principal component analysis (PCA) of 16 abiotic parameters exposed variation in habitat conditions between sites near and far from outlets. Increased levels of nitrates, turbidity, and specific conductance were often associated with sites near outlets. These findings demonstrate the strong impact of agricultural drainage ditches on coastal wetlands and stress the importance of protective land use policy.

Open and disturbed habitats support higher diversity of Syrphidae (Diptera)? A case study during three yr of sampling in a fragment of Araucaria forest in southern Brazil.

The diversity of hoverflies in five different habitats of the Parque Estadual de Vila Velha, Ponta Grossa, Paraná , Brazil, from September 1999 to August 2002 was studied. These five areas had been exposed to various types of anthropogenic disturbance at different times, which resulted in different stages of plant succession. In total, 2,841 specimens of 151 species of Syrphidae were collected using malaise traps. The highest species richness and abundance were found at the edge of the forest (Forest Edge), whereas the lowest was found in the most conserved areas. Evenness values increased along the succession gradient. The accumulation curve of new occurrences of syrphid species nearly approached an asymptote starting on the third month of the third year. Estimates of syrphid species richness using different methods indicated that between 155 and 288 species are found in the study area, according the Michaelis–Menten and the Chao2 estimators, respectively. The richness and abundance of representatives of the subfamily Syrphinae were higher in more open areas, where herbaceous plants predominate. Nineteen hoverfly species can be considered as environmental indicators, as they were collected exclusively or mainly in one of the defined habitat types. The degree of opening of the vegetation seems to be the factor determining the distribution of Syrphidae species, a conclusion based on the finding that grassy clearings in Araucaria Forests had more species. Hence, we conclude that, to become established, Syrphidae communities need conserved mosaic landscapes.

The effects of four types of anthropogenic disturbances on composition and abundance of terrestrial isopods (Isopoda: Oniscidea)

The Brazilian Atlantic Forest is currently reduced to about 12% of its original range. Among the components that make up its great diversity, there are species with the potential to be bioindicators, which can be very important for conservation-oriented studies. This study compares the species composition, abundance and sex ratio of terrestrial isopods in sites that show different anthropogenic disturbance histories and are located within four reserves in the Atlantic Forest of southwestern Brazil. Our study explores these crustaceans as indicators of anthropogenic disturbance. The influence of one of the following factors was explored in each protected area: 1) history of vegetation harvesting, 2) trail management, 3) Eucalyptus planting, and 4) edge effect. A total of 2,217 individuals of six species (Atlantoscia sp., Benthana werneri Lemos de Castro, 1958, Pseudodiploexochus tabularis (Barnard, 1932), Pudeoniscus obscures Lemos de Castro, 1973, Styloniscus spinosus (Patience, 1907), and Trichorhina sp.) were captured in pitfall traps. The composition of isopod species was different between most of the contrasting sites within reserves, and was similar among the less disturbed sites of different reserves. The total number of isopod individuals and the sex ratio were not different between the contrasting sites within most of the reserves and only the sex ratio of Atlantoscia sp. differed between contrasting sites of one protected area. Upon an individual analysis of each species, S. spinosus (an exotic species) was most abundant in more disturbed sites. The distributions of B. werneri and Atlantoscia sp. over time were relatively synchronous, except where S. spinosus was abundant. Our results also indicate that the exotic species S. spinosus may benefit from the vegetation mosaic produced by disturbance, so differences in abundance of this species may be useful for bioindication. A change in the spatial and temporal structure of Oniscidea communities caused by anthropogenic disturbance may have a cascade effect on ecological cycles because terrestrial isopods play a fundamental role in nutrient cycling.

Tissue Nutrient Content in Ulva spp. (Chlorophyceae) as Bioindicator for Nutrient Loading Along the Coast of East Africa

Although macroalgae usually are inconspicuous on pristine coral reefs, they often thrive on reefs that are subjected to various types of anthropogenic disturbance. This thesis consists of five papers and investigates how biomass and composition of macroalgal communities on coral reefs are affected by regulating factors, such as nutrient availability, herbivory, substrate availability and hydrodynamic forces. In addition, ecological functions and potential impacts of both wild and farmed macroalgal communities are evaluated. Paper I describes a method for using macroalgal tissue nutrient concentrations as bioindicator for nutrient availability, with the possibility to map nutrient loading from larger coastal cities. Papers II and III are manipulative studies comparing top-down and bottom-up regulation of macroalgal communities, where herbivore consumption seems to be the main regulator of biomass whereas nutrient availability mainly influences community composition. Exclosure of large-bodied herbivores had a positive influence on algal biomass in both studies, and during different climatic periods. Paper III also includes the influence of hydrodynamic forces on algal community biomass and structure by comparing a reef crest and a back reef-habitat. Alterations of top-down and bottom-up regulation generally had a stronger effect within the protected back reef-habitat, suggesting that such environments may be more sensitive to anthropogenic influence. Paper IV confirms the general conclusions from papers II and III by studying macroalgal biomass and composition on reef sites with different environmental prerequisites. This study also supports the notion that herbivorous fish can suppress accumulation of macroalgal biomass if substrate availability is low, but not where coral cover is reduced and plenty of substrate is open to macroalgal colonization. The study also found a large temporal variation of macroalgal standing stock and associated nutrients at sites with low top-down regulation. Paper V evaluates potential impacts of seaweed farming on coral reefs and nutrients in the seascape by experimentally studying growth, survival and nutrient binding capacity of Eucheuma denticulatum. This study showed that seaweed farms counteract eutrophication through nutrient extraction and that the risk of farmed algae colonizing local reefs seems to be small as they were rapidly consumed. In conclusion, the studies in this thesis contribute to the understanding of macroalgal regulation and function in tropical seascapes, thereby adding to the knowledge base for coastal management.

Pheromone Propagation Controller: The Linkage of Swarm Intelligence and Advanced Process Control

Statistical process control (SPC) is traditionally used in advanced process control (APC). However, SPC, which treats measurements as a series of isolated statistical data, employs different methods to deal with different problems. In this paper, we present a new perspective on process control, which treats the of the process in different runs as a social insect colony. Our novel algorithm, called the pheromone propagation controller (PPC), is a meta-heuristic method based on the assumption that the of the linear regression model have their own behavior and affect others nearby on different runs. The pheromone basket is an environment initially filled with intercepts, and then the intercepts pheromones in the basket propagate according to the modified digital pheromone infrastructure. After propagation, the intercept in the next run can be forecast by extrapolating the last two entities of the pheromone basket. Consequently, a revised process recipe can be obtained from the forecast and the linear regression model. We also propose a workable scheme for adaptively tuning the PPC propagation parameter. We discuss the PPC stability region and the strategy for tuning the propagation parameter as well as the effects of size of pheromone basket, model mismatch on the performance. Our simulation results show that the standard deviation and the mean square error for PPC, whether fixed or self-tuning, are more consistent than that of the EWMA, the predictor corrector control (PCC), and the double EWMA for five types of anthropogenic disturbance. We also examined a hybrid disturbance obtained from semiconductor fabrication. When system drifts, the PPC was superior to the other candidate controllers for all values of the PPC propagation parameters and weightings of the other controllers, whether fixed or self-tuning.

First steps in developing a multimetric macroinvertebrate index for the Ohio River

AbstractThe causes of degradation of aquatic systems are often complex and stem from a variety of human influences. Comprehensive, multimetric biological indices have been developed to quantify this degradation and its effect on aquatic communities, and measure subsequent recovery from anthropogenic stressors. Traditionally, such indices have concentrated on small‐to medium‐sized streams. Recently, however, the Ohio River Fish Index (ORFIn) was created to assess biotic integrity in the Ohio River. The goal of the present project was to begin developing a companion Ohio River multimetric index using benthic macroinvertebrates. Hester–Dendy multiplate samplers were used to evaluate benthic macroinvertebrate assemblages in relation to a gradient of water quality disturbance, represented by varying distances downstream of industrial and municipal wastewater outfalls in the Ohio River. In August 1999 and 2000, samplers were set every 100 m downstream of outfalls (12 outfalls in 1999, 22 in 2000) for 300–1000 m, as well as at upstream reference sites. Candidate metrics (n = 55) were examined to determine which have potential to detect changes in water quality downstream of outfalls. These individual measures of community structure were plotted against distance downstream of each outfall to determine their response to water quality disturbance. Values at reference and outfall sites were also compared. Metrics that are ecologically relevant and showed a response to outfall disturbance were identified as potentially valuable in a multimetric index. Multiple box plots of index scores indicated greater response to outfall disturbance during periods of low‐flow, and longitudinal river‐wide trends. Evaluation of other types of anthropogenic disturbance, as well as continued analysis of the effects of chemical water quality on macroinvertebrate communities in future years will facilitate further development of a multimetric benthic macroinvertebrate index to evaluate biotic integrity in the Ohio River. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Edge effects on flower‐visiting insects in grapefruit plantations bordering premontane subtropical forest

Summary Over the last decade, there has been much concern about the decline in pollinator abundance and diversity caused by different types of anthropogenic disturbances, including deforestation and habitat fragmentation. However, little empirical information exists documenting this decline and its consequences for cultivated flowering crops. We tested the hypothesis that remnants of natural habitats act as a source of flower‐visiting insects for neighbourhood crops. Over 3 consecutive years we evaluated flower‐visiting insect diversity, visitation frequency and composition in four grapefruit Citrus paradisi Macf. plantations at increasing distances (edge, 10, 100, 500 and 1000 m) from remnants of subtropical premontane forest in NW Argentina. The frequency of visits to grapefruit flowers decreased by more than twofold as distance to the forest increased and the flower‐visiting fauna became more depaupurate. Even the feral africanized honeybee Apis mellifera, the dominant flower visitor to grapefruit flowers, showed a decline at distances &gt; 500 m from the forest edge. However, the greatest relative declines occurred among stingless and solitary bees as well as other native flower visitors, which were rarely seen a few hundred metres inside the plantations. In addition, flower‐visiting insect faunas among plantations became more homogeneous as distance from the edge increased. These trends were consistent over years and among plantations up to 50 km apart. Thus, we can conclude that negative forest edge effects on flower‐visiting insects inside grapefruit plantations are widespread in the increasingly deforested landscape of NW Argentina. Synthesis and applications. This study provides empirical evidence for considering remnants of natural habitats as a source of both native and alien flower‐visiting insects that can be potential pollinators for agriculture. Increasing edge density in agricultural lands, through preservation and restoration of natural habitats, can foster stocks of diverse and abundant insect pollinators.

Calculating Highly Fluctuated Suspended Sediment Fluxes from Mountainous Rivers in Taiwan

Small drainage basins, highly fractured rock, high relief, and steep gradients make Taiwan watersheds particularly sensitive to episodic events such as typhoons and earthquakes, and to various types of anthropogenic disturbance. Here we analyze the characteristics of a long-term hydrological dataset from Taiwan and re-evaluate methods used to calculate sediment loads for Taiwan's event-driven rivers. We suggest using the rating curve method stratified clown to seasonal levels to reflect the rapid changes in the relationship between water discharge and suspended sediment load. A program is developed to determine the optimal time-interval for constructing rating curves, and is used to calculate hourly, daily, yearly, and long-term mean suspended sediment loads. Seasonal rating curves applied to hourly discharges are particularly critical to calculate sediment fluxes and concentrations in response to episodic events, particularly typhoons. The calculated cumulative long-term mean sediment fluxes for the Jhou-Shuei and Bei-Nan Rivers are considerably smaller than those calculated using monthly weighted average (MWA) method (Dadson et al. 2003). The MWA method likely over-estimates the mean load clue to more frequent sediment observations during high-flow events.

Effects of disturbance on phosphorus turnover and plankton dynamics

In coastal lagoons, one common type of anthropogenic disturbance is opening of the sand barriers that isolate these lagoons from the sea. We investigated how a disturbance caused by an artificial opening of the sand barrier affects phytoplankton and bacterioplankton dynamics and alkaline phosphatase activities (APA) in a Brazilian coastal lagoon. We propose an index of potential phosphorus turnover time (PPTT) calculated as the ratio of total phosphorus (TP) and APA in an attempt to quantify the effect of disturbances on phosphorus recycling within the plankton community. Opening the harrier caused increased phytoplankton biomass, TP concentrations, APA and PPTT, and decreased bacteria to phytoplankton biomass ratio. PPTT is easily calculated and may be used to detect plankton responses to anthropogenic disturbances.