Effects Of Anthropogenic Disturbance Research Articles

Influence of Elevation and Anthropogenic Disturbance on Woody Species Composition, Diversity, and Stand Structure in Harego Mountain Forest, Northeastern Ethiopia

Environmental variables like elevation affect species composition, diversity, distribution, density, and horizontal and upward growth. Ecologists are constantly working to better understand how species diversity varies along elevational gradients, particularly in mountainous ecosystems. Therefore, the purpose of this research was to examine the species’ horizontal and vertical structural diversity along the Harego Mountain Forest’s elevational gradient. The area was categorized into lower, middle, and upper elevations. A total of 67 (20 m × 20 m) plots were created along gradients of elevation 2,079–2,516 meters above sea level (m a.s.l.). Information for floristic composition, diversity, stand structure, and environmental variables were measured and recorded for each plot over the three elevational gradients. Data on anthropogenic disturbances were visually evaluated for every plot in every gradient of elevation. For the diversity analysis, Hill’s diversity statistics were employed. To find significant variations between the three elevational gradients in terms of Hill’s diversity number, stand structure, and environmental variables, the one-way analysis of variance with SPSS version 26 at the 0.05 level of significance was carried out. The finding revealed that 50 woody plants that belonged to 35 families and 44 genera in the 67 sample plots with an elevation of 2,079 to 2,516 were identified. Shrubs were dominant in each elevational gradient. Species richness, abundance, and Hill’s diversity number were all significantly ( p < 0.05 ) greater in the upper elevational gradient of the forest. On the other hand, all stand structures were significantly ( p < 0.05 ) higher in the middle elevational gradient. The effect of anthropogenic disturbances and environmental variables were clearly observed in the lower and upper elevational gradients than in the middle elevation. As a result, there were fewer seedlings, saplings, trees, and shrubs in the gradients of lower and higher elevations. For the conservation of the forest, it is crucial to pay special attention to biotic elements at lower elevations and abiotic factors at higher elevations. Accordingly, involving the local community in forest management, reducing anthropogenic pressure in and around the Harego Mountain Forest through tree planting in farmlands and woodlots and implementing physical soil and water conservation structures are recommended.

Anthropogenic disturbance affects specialist, but not generalist, endophagous insects associated with two African grasses: implications for biological control

ABSTRACT The specialisation-disturbance hypothesis (SDH) predicts that specialist and generalist taxa respond differently to disturbance, with generalists more tolerant of disturbance, while habitat stability (i.e. no/limited disturbance) should favour specialist species. If the SDH holds true, this would have implications for the design and implementation of biological control programmes, in terms of performing native-range surveys in search of candidate agents and subsequent development of management programmes for their release in the weeds invaded range. We assessed the effect of anthropogenic disturbance (mowing/slashing and fire) on the endophagous insect communities associated with two African grasses, Sporobolus pyramidalis and Sporobolus natalensis (Poaceae), that are targets for biological control in Australia. Comparisons, of insect community structure and presence/abundance of each species between disturbed and undisturbed sites, were made at 19 sites in South Africa. Disturbance caused a shift in insect species composition and abundance, whereby specialist insects were less frequently encountered and less abundant at disturbed versus undisturbed sites. If the potential agents for Sporobolus spp. are released in Australia they may be negatively affected by disturbance and may therefore be incompatible with certain integrated management strategies, such as mowing and prescribed burning. Moreover, our results suggest that field sites with limited disturbance should be prioritised during native-range surveys to maximise the chances of locating specialist natural enemies. The effect disturbance has on insect community composition may be particularly relevant for the biological control of invasive grasses, due to the intensity of disturbance of grasslands worldwide.

The effects of anthropogenic disturbance and seasonality on the ant communities of Lang Tengah Island.

Anthropogenic disturbances and seasonal changes significantly impact diversity and community composition of ants, but their effects are often intertwined. We investigated these drivers on Lang Tengah Island, a location with a pronounced monsoon season and three resorts that close during this period. We surveyed four sites, two disturbed and two undisturbed, before and after the monsoon season, using pitfall traps to sample epigaeic ant communities. Undisturbed habitats had higher species diversity, but both habitats (undisturbed and disturbed sites) have a high proportion of ants with characteristics of being encroached by generalist and invasive/tramp ant species. Post-monsoon sampling yielded an increase in species richness and diversity. Seasonal changes, such as monsoonal rains, can temporarily alter ant interactions and resource distribution, potentially maintaining diversity. Future studies should validate these findings for ant communities under similar pressures, using ant composition and functional roles for conservation and management purposes.

The Effects of Anthropogenic Disturbances on the Spatiotemporal Patterns of Medium-Large Mammals in Tropical Volcanic Landscapes.

A comprehensive understanding of the consequences of human interactions with mammals is a critical factor in supporting and conserving species in landscapes dominated by humans, which are increasingly threatened. This study aimed to identify the spatial and temporal interactions between humans and mammals. A non-parametric statistical approach with kernel density was used to detect human-mammal temporal interactions. The species interaction factor (SIF) was applied to calculate the spatial overlap based on the two-species occupancy detection model. The activity patterns of medium mammals were nocturnal, diurnal, and cathemeral. The human-medium mammal pairs with SIF values that were <1 and statistically significant included the human-long-tailed macaque (Macaca fascicularis) pair, the human-leopard cat (Prionailurus bengalensis) pair, and the human-barking deer (Muntiacus muntjac) pair. Based on their SIF values and the high overlap in their activity times, the human-macaque pairings had a high risk of conflict. Barking deer and leopard cats displayed a coexistence with humans via time-sharing activities. Due to temporal niche variations with human activities, the existence of nocturnal mammals was relatively uninterrupted. This study showed that most mammals are able to adapt spatially and temporally to various human activities. Nonetheless, efforts to mitigate human-wildlife conflict must be maintained, particularly in the case of severely endangered species, such as the Sunda pangolin.

Meiofauna: Anthropogenic impacts on hidden players in ecosystem

AbstractCertain aspects of meiobenthos research are given detailed and comprehensive attention in Chapter 7 (Hidden players: meiofauna mediate ecosystem effects of anthropogenic Disturbances in the ocean) of the Springer publication ‘New Horizons in Meiobenthos Research; Profiles, Patterns and Potential’ (O. Giere &amp; M. Schratzberger (Eds.). This book review is concerned solely with Chapter 7 which underlines the view that meiofaunal species play a very important part as hidden players in the impacts of anthropogenic disturbances in the ocean, an aspect justifiably arousing global concerns. The chapter constitutes a veritable compendium where much that was previously unsuspected in those ‘untouched reaches’, is revealed under the scrutiny of its many internationally known authors. Of its ten sections, eight deal consecutively with the impact of disturbances caused by anthropogenic activities such as bottom fishing, pollution from organic sources, hydrocarbons, oil and chemical impacts, invasive species and climate change, followed by a section on the resilience of the meiofauna to such disturbances and the scale of their responses, with a final section outlining a forward perspective for future research. In addition, Chapter 7 contains an extensive bibliography which itself constitutes an important reference resource for researchers.

Effects of Anthropogenic Disturbance and Seasonal Variation on Aerobiota in Highly Visited Show Caves in Slovenia.

Aerosols in caves are natural tracers and, together with climatic parameters, provide a detailed insight into atmospheric conditions, responses to climatic changes and anthropogenic influences in caves. Microbiological air monitoring in show caves is becoming increasingly useful to understand changes in cave ecosystems and to implement and review measures for sustainable cave use and tourism development. In 2017 and 2018, air along tourist trails in caves Postojnska jama and Škocjanske jame (Slovenia) was sampled before and after tourist visits. Samples were analysed using culture-dependent methods, flow cytometry, detection of β-D-glucan and lipopolysaccharide and compared with CO2 and temperature data to measure anthropogenic influences and seasonality on aerobiota. While the presence of tourists significantly increased concentrations of airborne microorganisms (p < 0.05), β-D-glucan and CO2 did not show such a trend and were more dependent on seasonal changes. Locally, concentrations of cultivable microorganisms above 1000 CFU/m3 were detected, which could have negative effects on the autochthonous microbiota and possibly on human health. A mixture of bacteria typically associated with humans was found in the air and identified with MALDI-TOF MS. Using MALDI-TOF MS, we achieved a 69.6% success rate in identification. Micrococcus luteus, Streptococcus mitis, Staphylococcus epidermidis and Moraxella spp. were recognized as good indicators of cave anthropisation.

Effect of typhoons on spatiotemporal patterns of multi-group persistent organic pollutants in sediment of Chinese southeastern coastal estuaries

Estuaries are susceptible to both anthropogenic disturbances and global climate changes. Impacts may be discriminated by pollution patterns of widely quantified persistent organic pollutants (POPs), though data are scarce for extreme climate events. This study quantified four groups of POPs, i.e., polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), and hexachlorocyclohexanes (HCHs), in sediments from seven Chinese coastal estuaries across a gradient of socioeconomic development in their watersheds with comparisons among the pre-typhoon, typhoon, and post-typhoon periods during 2016–2019. The maximal average concentrations, up to 1561 μg PAHs kg−1, 235 μg DDTs kg−1, and 38.9 μg HCHs kg−1, were quantified in the Jiulong River estuary and 7.61 μg PCBs kg−1 in the Jiao River estuary. Anthropogenic activities contributed to the distinctive spatial distributions of four groups of POPs in estuaries with non-agricultural gross domestic product (NAGDP) per capita significantly relating to sedimentary concentrations of PAHs and PCBs and agricultural gross domestic product (AGDP) per capita relating to DDTs and HCHs. Seasonality and typhoons led to less temporal variations in sedimentary POPs concentrations, whose spatial heterogeneity was remarkably reduced in the post-typhoon period rather than in the pre-typhoon and typhoon periods. The results of this study suggested that fingerprinting legacy POPs in spatial and temporal distributions contributed to identifying the effects of anthropogenic disturbances and climate changes on estuarine sediment quality.

Common chironomids drive the biodiversity–temperature relationship during the Younger Dryas-Holocene transition in a southern Baltic coastal lake

The Younger Dryas-Holocene transition represents a period of significant thermal change, comparable in magnitude to modern warming, yet in a colder context and without the effect of anthropogenic disturbance. This is useful as a reference to tackle how biodiversity is affected by temperature in natural conditions. Here, we addressed the thermal change during this period in a southern Baltic coastal lake (Konarzewo Lake, Poland), as inferred by chironomid remains. We evaluated changes in chironomid communities and used Hill numbers to explore how commonness and rarity underlie biodiversity changes attributable to warming. We found evidence of warming at Konarzewo Lake during the Younger Dryas-Holocene transition, with inferred temperatures in the Younger Dryas period supporting the NW–SE gradient in Younger Dryas summer temperatures across Europe. Chironomid communities drastically changed during the thermal transition. However, Hill numbers showed no response to temperature when rare morphotypes were emphasized (order q = 0) or a weak response when they were balanced with common morphotypes (order q = 1). Hill number of order q = 2, emphasizing the most common morphotypes, consistently increased with temperature across different sample sizes or coverages. This illustrates how common morphotypes, rather than the rare ones, may boost biodiversity facing warming.

Conservation decision support for Silver Chub habitat in Lake Erie

AbstractObjectiveConservation and restoration of aquatic species is difficult, especially for rare species, because their habitats are typically disturbed, obscuring the natural ability of the habitat to support each species. The Lake Erie population of Silver Chub Macrhybopsis storeriana struggles to sustain itself in a habitat disturbed by a wide spectrum of anthropogenic factors. Application of multiple model predictions can provide indications of conservation or restoration opportunities for this species.MethodsA combination of models that predict the best potential for Lake Erie habitat to support Silver Chub and the effects of anthropogenic disturbances on that population were used to identify habitat conditions throughout the western aquatic lake unit.ResultAs many as 76 combinations of best habitat potential and disturbance conditions were present, but the best opportunities occurred in &lt;12% of the study area. Some of the best protection opportunities were farthest offshore, and extensive areas of least disturbed habitat for restoration were near the southern and western shores. The location‐specific model predictions provide fine‐scale decision support for Silver Chub habitat protection or restoration.ConclusionThe approach applied here may help identify compatibilities among species to achieve the desirable fish community for Lake Erie and reconcile conflicting management actions.

The impacts of human-induced disturbances on spatial and temporal stream water quality variations in mountainous terrain: A case study of Borcka Dam Watershed

Unaltered watersheds with natural vegetation cover (forest, grasslands, etc.) provide several ecological benefits in addition to providing freshwater, controlling water levels, and supporting flourishing streamside ecosystems. However, as in many watersheds in the World, the research area in this study, the Borcka Dam Watershed (BDW), has been affected by many human-induced disturbances affecting a wide area of forest and grassland areas as well as soil and water resources. Therefore, the objective of this study was to assess and evaluate the possible effects of anthropogenic disturbances, particularly on annual changes in water discharge, some water quality parameters, and total suspended sediment (TSS) amounts in the main streams of four sub-watersheds (Fabrika, Godrahav, Hatila, and Murgul) and the reservoir of the dam. In addition, we intend to confirm that land use change and/or transformation play a significant role in influencing stream water quality. The YSI/Professional-Plus, a portable water quality measurement device, was used to determine the amounts of pH, dissolved oxygen (DO), total dissolved substance (TDS), ammonium (NH4–N), nitrate (NO3–N), salinity, electrical conductivity (EC), and temperature besides measuring discharge and total suspended sediments (TSS) from a total of 27 sampling points in the field. Although the results revealed that the annual mean values of all water quality parameters for all four streams were mostly in good condition, for some time and points of the measurements, several parameters were found to be above the official water quality standards due to the intensive aforementioned anthropogenic activities, particularly in the stream waters of Murgul (e.g. pH and TSS being 10,84 and 236 mg/L, respectively) and Fabrika (e.g. EC of 412 μs/cm; DO of 4.44 mg/L; 14 ml of NO3–N) sub-watersheds. These outcomes indicate that these two sub-watersheds have been impacted more severely by the human-induced disturbances compared to Hatila and Godrahav sub-watersheds.

Impact of anthropogenic disturbance on nesting Chimney Swift (&lt;i&gt;Chaetura pelagica&lt;/i&gt;) including best practices for conservation

The effect of anthropogenic disturbance on nesting Chimney Swift (Chaetura pelagica) is poorly described. We review five case studies of anthropogenic disturbance around Chimney Swift nest sites caused by building construction, demolition, and maintenance activities in St. Adolphe, Manitoba. Chimney Swift behaviour and nest site activity did not appear to be overtly influenced by building demolition and construction conducted on adjacent buildings or lots within 13–30 m of nest chimneys. In contrast, Chimney Swift behaviour and breeding success appeared to be negatively affected by loud interior renovations and rooftop work conducted in or on the same building as the nest chimneys. The presence of humans on the roof of the nest building prevented Chimney Swifts from entering the nest site and reduced the overall rate of feeding young. Based on these observations, we provide conservation best practices for building construction and maintenance projects conducted within or on the same building as nest chimneys to help ensure protection of Chimney Swifts and their nesting habitat during the breeding season.

Study of the urban-impact on microbial communities and their virulence factors and antibiotic resistance genomes in the Nandu River, Haikou

Objective: To explore the changes in bacterial community structure, antibiotic resistance genome, and pathogen virulence genome in river water before and after the river flowing through Haikou City and their transmission and dispersal patterns and to reveal anthropogenic disturbance's effects on microorganisms and resistance genes in the aquatic environment. Methods: The Nandu River was divided into three study areas: the front, middle and rear sections from the upstream before it flowed through Haikou City to the estuary. Three sampling sites were selected in each area, and six copies of the sample were collected in parallel at each site and mixed for 3 L per sample. Microbial community structure, antibiotic resistance, virulence factors, and mobile genetic elements were analyzed through bioinformatic data obtained by metagenomic sequencing and full-length sequencing of 16S rRNA genes. Variations in the distribution of bacterial communities between samples and correlation of transmission patterns were analyzed by principal co-ordinates analysis, procrustes analysis, and Mantel test. Results: As the river flowed through Haikou City, microbes' alpha diversity gradually decreased. Among them, Proteobacteria dominates in the bacterial community in the front, middle, and rear sections, and the relative abundance of Proteobacteria in the middle and rear sections was higher than that in the front segment. The diversity and abundance of antibiotic resistance genes, virulence factors, and mobile genetic elements were all at low levels in the front section and all increased significantly after flow through Haikou City. At the same time, horizontal transmission mediated by mobile genetic elements played a more significant role in the spread of antibiotic-resistance genes and virulence factors. Conclusions: Urbanization significantly impacts river bacteria and the resistance genes, virulence factors, and mobile genetic elements they carry. The Nandu River in Haikou flows through the city, receiving antibiotic-resistant and pathogen-associated bacteria excreted by the population. In contrast, antibiotic-resistant genes and virulence factors are enriched in bacteria, which indicates a threat to environmental health and public health. Comparison of river microbiomes and antibiotic resistance genomes before and after flow through cities is a valuable early warning indicator for monitoring the spread of antibiotic resistance.

Modeling the impacts of a changing and disturbed environment on an endangered beluga whale population

Climate change and disturbance from human activities are key threats facing many wildlife populations worldwide. The ability to quantify the effects of such threats on individual health and population dynamics is critical for effective management and conservation. We used Stochastic Dynamic Programming (SDP), a method for implementing state-dependent life history theory, to explore the impacts of changes in prey availability and anthropogenic disturbance on survival and reproductive success of Cook Inlet belugas (Delphinapterus leucas, CIB), an endangered and isolated population in decline. We predicted behavioral decisions (whether to forage, travel to a new location, or rest) of pregnant CIBs within a spatially and seasonally dynamic prey landscape. We used those decisions to explore time-activity budgets and spatial use under a variety of hypothetical environmental scenarios and estimate the resulting impacts on body condition and vital rates. In all scenarios, foraging activity was highest during summer to capitalize on abundant prey, which in the model was assumed to be eulachon (Thaleichthys pacificus) and salmonids (Oncorhynchus spp.). This resulted in large increases in blubber reserves that pregnant CIBs relied on during October to April when prey was assumed to be less abundant. Prey availability outside of summer months was still critical, as it either exacerbated or buffered against reductions in prey availability during summer months. Spatial predictions of habitat use indicated that pregnant CIBs should forage in areas used historically that now appear to be abandoned, suggesting that prey availability alone is unlikely to explain the recent range contraction of CIBs to upper Cook Inlet. Reductions in prey availability from late spring to early fall adversely affected vital rates, but intermittent disturbances that resulted in lost foraging opportunities, such as those caused by anthropogenic activities during the ice-free season, had little impact on body condition or vital rates if prey were abundant during the summer and early fall. Accurate assessment of the effects of anthropogenic disturbance on CIBs requires robust data on both disturbances and year-round prey availability, as intermittent disturbances adversely affected survival and reproductive success when they occurred in environments with reduced prey availability. Our model represents an initial effort to fill a critical information gap for informing CIB management decisions, providing insights into conditions under which reductions in vital rates might be expected and highlighting key data needed to increase the applicability of the model to this endangered population.

Natural Protected Areas effect on the cover change rate of mangrove forests in the Yucatan Peninsula, Mexico

Mangrove forests provide important ecosystem services that support the maintenance of coastal socio-ecological systems. Strategies such as the establishment of Natural Protected Areas (NPAs) have been encouraged worldwide to promote their conservation. However, mangroves are still being lost as a consequence of anthropogenic disturbance and environmental variation. In here, we determine the change rate in mangrove cover, between 2005–2015, in eight coastal NPAs and the corresponding four km adjacent transition area in the Yucatan Peninsula (YP), and assess the relationship with location (inside or outside the protected area), their time since establishment and distance to roads. In general, we observed higher positive rates of change in mangrove cover inside the protected areas than in the adjacent transition zones (p < 0.05). Change was related to both the distance to roads and the time since establishment of the NPAs (p < 0.05). Higher (positive and negative) mangrove rates of change were observed in areas closer to roads, and more stable areas were detected as the distance to the roads increased. The positive rate of change also increased with the age of the protected area. These patterns were more evident inside the NPAs. The continuous monitoring of mangrove change dynamics in protected areas in this important region and their drivers, is necessary to establish effective management strategies considering the spatial and temporal variability of environmental and anthropogenic disturbances.

Effect of Anthropogenic Disturbances on the Microbial Relationship during Bioremediation of Heavy Metal-Contaminated Sediment.

Soil, sediment, and waters contaminated with heavy metals pose a serious threat to ecosystem function and human health, and microorganisms are an effective way to address this problem. In this work, sediments containing heavy metals (Cu, Pb, Zn, Mn, Cd, As) were treated differently (sterilized and unsterilized) and bio-enhanced leaching experiments were carried out with the addition of exogenous iron-oxidizing bacteria A. ferrooxidans and sulfur-oxidizing bacteria A. thiooxidans. The leaching of As, Cd, Cu, and Zn was higher in the unsterilized sediment at the beginning 10 days, while heavy metals leached more optimally in the later sterilized sediment. The leaching of Cd from sterilized sediments was favored by A. ferrooxidans compared to A. thiooxidans. Meanwhile, the microbial community structure was analyzed using 16S rRNA gene sequencing, which revealed that 53.4% of the bacteria were Proteobacteria, 26.22% were Bacteroidetes, 5.04% were Firmicutes, 4.67% were Chlamydomonas, and 4.08% were Acidobacteria. DCA analysis indicated that microorganisms abundance (diversity and Chao values) increased with time. Furthermore, network analysis showed that complex networks of interactions existed in the sediments. After adapting to the acidic environmental conditions, the growth of some locally dominant bacteria increased the microbial interactions, allowing more bacteria to participate in the network, making their connections stronger. This evidence points to a disruption in the microbial community structure and its diversity following artificial disturbance, which then develops again over time. These results could contribute to the understanding of the evolution of microbial communities in the ecosystem during the remediation of anthropogenically disturbed heavy metals.

Characteristics of the Stone Crayfish Population along a Disturbance Gradient—A Case Study of the Kustošak Stream, Croatia

The stone crayfish, Austropotamobius torrentium, is a native European freshwater species sensitive to habitat alterations such as stream channelization and urban development, putting its populations at risk. This study aims to assess how habitat alteration and subsequent water quality changes affect the stone crayfish population in the Kustošak Stream (Croatia) through three selected sites under different levels of anthropogenic disturbance: (1) undisturbed; (2) recently modified, and (3) long-time modified sites. At each site, crayfish were captured, measured, and marked to estimate population size, structure, and crayfish condition. Additionally, we examined whether water quality (18 measured physicochemical parameters) affects relative crayfish abundance. We also used mitochondrial sequencing and microsatellite genotyping to assess species genetic diversity and population connectivity and to compare results among the sites. The results showed that habitat alteration caused an overall reduction in population abundance and changes in size structure; however, it had not yet resulted in detectable genetic differences. Partial least squares regression showed that crayfish abundance was affected by the physicochemical parameters of water, including, among others, oxygen, calcium ions, nitrates, pH, and water temperature. We discuss our findings in the context of the effects of anthropogenic disturbance on the viability and persistence of this EU priority species.

Effects of Anthropogenic Disturbance of Natural Habitats on the Feeding Ecology of Moorish Geckos.

Urbanization and anthropic influences can drastically modify a natural habitat and transform it into an easily recognizable "urban habitat". Human activities can also induce less severe modifications of what apparently might still look like natural habitats. Therefore, these subtle alterations may be hidden but can still cause important negative effects on plant and animals. In contrast, some species seem able to take advantage of these anthropic alterations. Here, we examined the possible effects of the anthropogenic disturbance of an apparent natural habitat on the feeding ecology and body condition of Moorish geckos, Tarentola mauritanica. For this, we compared microhabitat structure, invertebrate availability, the diet composition (estimated from fecal contents), diet selection patterns and body condition of the two populations of geckos inhabiting two contiguous small islands. These islands have similar environmental characteristics, but highly contrasting differences in urbanization and anthropogenic influence. We found that, although the abundance of potential invertebrate prey was similar on both habitats, the diversity of invertebrate prey was lower in the altered habitat. As a consequence, although composition of the diet of geckos was similar on both islands, the diversity of prey and food niche breadth were lower in the altered habitat, and patterns of diet selection changed. However, these inter-habitat differences did not seem to affect the body size and body condition of geckos. We discuss how flexibility in feeding ecology may allow some species to cope with small anthropic disturbances of the habitat.

Effects of industrial disturbances on the flavonoid concentration ofRhododendron groenlandicum

The boreal forest is subject to various anthropogenic disturbances, including logging, mining, and hydroelectricity production and transport. These disturbances affect Indigenous communities and the culturally salient species they depend on for the practice of traditional and subsistence activities. Rhododendron groenlandicum (Oeder) Kron &amp; Judd is one such species whose leaves are used to treat various ailments, due to their concentration in biologically active chemicals such as flavonoids. Our objective was to assess the effect of anthropogenic disturbances on the chemical properties of R. groenlandicum on the territories of three Indigenous communities. Leaf samples were collected near mines, under hydroelectric power lines, and in non-disturbed sites. Our results showed that variations in flavonoid concentration were mainly related to territory ( R2= 0.43, P = 0.0005), while disturbance type had a smaller effect ( R2= 0.18, P = 0.02). Samples from Nemaska, the northernmost territory with the most open forest stands, had higher concentrations of epicatechin (+23%, P = 0.03). Quercetin-3-glucoside concentrations were lower near mines (−19%, P = 0.01). The effects of disturbances on the chemical signature of R. groenlandicum are complex, and a complete assessment of the consequences of industrial activity on Indigenous landscape value must take into account other culturally salient species.

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.