Human-mediated Disturbances Research Articles

Maternal effects of human-mediated disturbances on the growth and reproductive traits of different ecotypes of an annual invasive plant Erigeron annuus

A multifactorial combination of human-mediated disturbances is now recognized as a major driver of the global rise and spread of invasive alien plants. Among the numerous invasive alien plants, annuals have fast adaptability and evolution via maternal effect in human-mediated disturbance environments, such as chemical and physical controls. The characteristic enables them to quickly disperse and establish new habitats. Thus, understanding the adaptability and evolution of invasive plants in response to multifactorial human-mediated disturbances is crucial for developing effective management strategies to control their spread and minimize their impacts on ecosystems and human activities. In order to test the growth and reproductive responses in both the parent and offspring generations, two ecotypes (clump and scatter) of an annual invasive plant, Erigeron annuus, were subjected to simulated trampling, defoliation (simulated herbivory), and herbicide disturbances. We found that disturbances negatively affected the growth and reproduction of E. annuus in parent and offspring generations. In comparison to the scatter ecotype plants, the clump ecotype plants had greater growth and reproductive production, as well as a reduced maternal interference effect to cope with human-mediated disturbances. It enhanced the adaptability of their offspring to disturbances. The findings imply that the evolutionary advantage of clump ecotype plants may explain why they can thrive in disturbed habitats and become invasive in some regions.

Rapid diversity assessment of litter myxomycete assemblages in the upland and coastal terrains of San Fernando City, La Union, Philippines

Abstract. Balaoro-Banzuela RC, Ocenar-Bautista CE, Buebos-Esteve DE, Claudio-Paragas CY, Limbo-Dizon JE, Dagamac NHA. 2023. Rapid diversity assessment of litter myxomycete assemblages in the upland and coastal terrains of San Fernando City, La Union, Philippines. Biodiversitas 24: 2877-2886. Over the past few years, increasing studies have been on diversity assessments of myxomycetes in the Philippines. Despite these, their utility as bioindicators to evaluate approaches for sustainable ecosystem management remains largely unexplored. Following the ridge-to-reef (R2R) approach, a comparative diversity assessment was conducted between the upland and coastal terrains of San Fernando City, La Union, Philippines. Aerial and ground litter were haphazardly collected and cultivated at ambient conditions using the moist chamber (MC) technique. MCs were highly productive, exhaustively yielding a total of 27 distinct species belonging to 10 different genera. Regarding abundance, 15 species were rare, and four were occasional, common, and abundant. Both species richness and occurrence of rare taxa were higher in the upland terrain than in the coastal terrain. However, several ?-diversity indices hinted at no significant difference in species diversity between terrains and substrates. At the community level, clustering analyses and other ?-diversity indices revealed that myxomycete assemblages were more similar in terrain than the substrate. This study implicates using myxomycetes as proxy biological models to reflect the ecological influences of plant heterogeneity and human-mediated disturbance. This allows its integration into local policymaking with adherence to R2R management.

Dramatic loss of seagrass Zostera marina L. suitable habitat under projected climate change in coastal areas of the Bohai Sea and Shandong peninsula, China

Seagrass is an important foundational species in marine ecosystems that plays an important role in providing ecosystem services. However, seagrass distribution and suitable habitat have rapidly declined in recent decades because of climate change and human-mediated disturbances. To achieved better conservation and management of the seagrass Zostera marina, an important representative seagrass in northern China, studies must investigate how this species responds to climate change. Here, we used an ensemble species distribution model to forecast the potential distribution and future suitable habitat change for the eelgrass Z. marina in coastal areas of the Bohai Sea and Shandong Peninsula, China. Two future climate scenarios, RCP 4.5 and RCP 8.5, were considered, which represent stable and high levels of greenhouse gas emissions, respectively. The ensemble model accurately predicted the current Z. marina distribution and performed better than the single-algorithm methods of random forest, generalized boosting model and maximum entropy according to performance matrices (AUC and TSS). The distance to land (78.50 ± 3.51%) and the maximum sea surface temperature (11.90 ± 0.25%) were the most important variables determining the distribution of Z. marina, while the contributions of other variables, maximum sea surface current velocity (3.80 ± 0.33%), minimum surface salinity (2.15 ± 0.22%) and water depth (1.74 ± 0.24%) were relatively low. Under future climate scenarios, the suitable habitat of Z. marina was predicted to decrease by more than half by the 2050s, whereas under the pessimistic greenhouse gas emission scenario (RCP 8.5), suitable Z. marina habitat was predicted to decrease by nearly 80% by the end of this century. The loss of Z. marina seagrass beds will have important ecological effects on the marine ecosystem. Our results not only provide valuable information to assist in identifying potential Z. marina meadows, but also have important implications for guiding conservation and management of Z. marina in the northern coastal region of China.

Mule deer fawn recruitment dynamics in an energy disturbed landscape.

Wildlife population dynamics are modulated by abiotic and biotic factors, typically climate, resource availability, density-dependent effects, and predator-prey interactions. Understanding whether and how human-caused disturbances shape these ecological processes is helpful for the conservation and management of wildlife and their habitats within increasingly human-dominated landscapes. However, many jurisdictions lack either long-term longitudinal data on wildlife populations or measures of the interplay between human-mediated disturbance, climate, and predator density. Here, we use a 50-year time series (1962-2012) on mule deer (Odocoileus hemionus) demographics, seasonal weather, predator density, and oil and gas development patterns from the North Dakota Badlands, USA, to investigate long-term effects of landscape-level disturbance on mule deer fawn fall recruitment, which has declined precipitously over the last number of decades. Mule deer fawn fall recruitment in this study represents the number of fawns per female (fawn:female ratio) that survive through the summer to October. We used this fawn recruitment index to evaluate the composite effects of interannual extreme weather conditions, energy development, and predator density. We found that density-dependent effects and harsh seasonal weather were the main drivers of fawn fall recruitment in the North Dakota Badlands. These effects were further shaped by the interaction between harsh seasonal weather and predator density (i.e., lower fawn fall recruitment when harsh weather was combined with higher predator density). Additionally, we found that fawn fall recruitment was modulated by interactions between seasonal weather and energy development (i.e., lower fawn fall recruitment when harsh weather was combined with higher density of active oil and gas wells). Interestingly, we found that the combined effect of predator density and energy development was not interactive but rather additive. Our analysis demonstrates how energy development may modulate fluctuations in mule deer fawn fall recruitment concurrent with biotic (density-dependency, habitat, predation, woody vegetation encroachment) and abiotic (harsh seasonal weather) drivers. Density-dependent patterns emerge, presumably due to limited quality habitat, being the primary factor influencing fall fawn recruitment in mule deer. Secondarily, stochastic weather events periodically cause dramatic declines in recruitment. And finally, the additive effects of human disturbance and predation can induce fluctuations in fawn fall recruitment. Here we make the case for using long-term datasets for setting long-term wildlife management goals that decision makers and the public can understand and support.

Shift of phytoplankton assemblages in a temperate lake located on the eastern route of the South-to-North Water Diversion Project

There remains no consensus on the effects of changes in the environment factors under the action of water diversions on phytoplankton communities. Herein the changing rules applying to phytoplankton communities subject to water diversion were unveiled based on long-term (2011–2021) time-series observations on Luoma Lake, located on the eastern route of the South-to-North Water Diversion Project. We found that nitrogen decreased and then increased, while phosphorus increased after operation of the water transfer project. Algal density and diversity were not affected by water diversion, while the duration of high algal density was shorter after water diversion. Phytoplankton composition had dramatic differences before and after water transfer. The phytoplankton communities exhibited greater fragility when they first experienced a human-mediated disturbance, and then they gradually adapted to more interferences and acquired stronger stability. We furthermore found the niche of Cyanobacteria narrowed while that of Euglenozoa widened under the pressure of water diversion. In addition to WT and DO, the main environmental factor before water diversion was NH4–N, whereas the effect of NO3–N and TN on phytoplankton communities increased after water diversion. These findings fill the knowledge gap as to the consequence of water diversion on water environments and phytoplankton communities.

Antipredator behaviors in urban settings: Ecological experimentation powered by citizen science.

Animal behaviors are often modified in urban settings due to changes in species assemblages and interactions. The ability of prey to respond to a predator is a critical behavior, but urban populations may experience altered predation pressure, food supplementation, and other human‐mediated disturbances that modify their responsiveness to predation risk and promote habituation.Citizen‐science programs generally focus on the collection and analysis of observational data (e.g., bird checklists), but there has been increasing interest in the engagement of citizen scientists for ecological experimentation.Our goal was to implement a behavioral experiment in which citizen scientists recorded antipredator behaviors in wild birds occupying urban areas. In North America, increasing populations of Accipiter hawks have colonized suburban and urban areas and regularly prey upon birds that frequent backyard bird feeders. This scenario, of an increasingly common avian predator hunting birds near human dwellings, offers a unique opportunity to characterize antipredator behaviors within urban passerines.For two winters, we engaged citizen scientists in Chicago, IL, USA to deploy a playback experiment and record antipredator behaviors in backyard birds. If backyard birds maintained their antipredator behaviors, we hypothesized that birds would decrease foraging behaviors and increase vigilance in response to a predator cue (hawk playback) but that these responses would be mediated by flock size, presence of sentinel species, body size, tree cover, and amount of surrounding urban area.Using a randomized control–treatment design, citizen scientists at 15 sites recorded behaviors from 3891 individual birds representing 22 species. Birds were more vigilant and foraged less during the playback of a hawk call, and these responses were strongest for individuals within larger flocks and weakest in larger‐bodied birds. We did not find effects of sentinel species, tree cover, or urbanization.By deploying a behavioral experiment, we found that backyard birds inhabiting urban landscapes largely maintained antipredator behaviors of increased vigilance and decreased foraging in response to predator cues. Experimentation in citizen science poses challenges (e.g., observation bias, sample size limitations, and reduced complexity in protocol design), but unlike programs focused solely on observational data, experimentation allows researchers to disentangle the complex factors underlying animal behavior and species interactions.

Human recreation impacts seasonal activity and occupancy of American black bears (Ursus americanus) across the anthropogenic-wildland interface

Protected areas serve an important role in wildlife conservation, yet most wildlife occur outside these areas, subject to varying degrees of human disturbance. In the Upper Peninsula of Michigan, American black bears (Ursus americanus), a highly mobile, opportunistic species, are common despite an extensive outdoor recreation industry with the potential to affect black bear spatial and temporal activity. We investigated how environmental and anthropogenic factors influence black bear occupancy, detection, and diel activity patterns across the anthropogenic–wildland interface before and after hibernation. Using 30 camera traps deployed across a rural–wildland interface, we captured black bears at 23 camera sites (~ 77%), which exhibited co-occurrence with humans at 10 sites (~ 33%), revealing that human presence and human population density exert negative effects on black bear seasonal occupancy. Bears were more nocturnal during the hunting season, before hibernation. Human recreational activity increased ~ 38% after hibernation, but bear diurnal activity also increased ~ 36%, except when cubs were present. Our results suggest bears prioritize avoiding humans spatially, rather than temporally, except during the hunting season and when cubs are present. Understanding black bear responses to human recreation patterns and environmental variation is essential for minimizing human-mediated disturbance, and fueling conservation efforts of large, charismatic carnivores.

Insufficient protection and intense human pressure threaten islands worldwide

The small size, degree of isolation, and particular evolutionary processes occurring in islands make them highly diverse and an essential target for conservation. For the same characteristics, they are also extremely vulnerable to human-mediated disturbances. During the last centuries, nearly 80% of species extinctions have occurred on islands. While there is information on the human threats, level of protection, and conservation importance of islands, an integrative picture combining these aspects and aimed at determining conservation priorities to inform decision-making is still missing. Here, we jointly analyzed these three aspects producing a worldwide island conservation assessment based on terrestrial vertebrates. Considering the Aichi target of >17% of protection and all protected area categories, we found that 5397 islands, encompassing a quarter of the worldwide island area, face high human modification and have a low level of protection, with 33% of them showing extreme levels of human modification. Also, if we were to consider the new threshold of protected area coverage proposed to accurately protect the world’s biodiversity and ecosystems (Nature Needs Half initiative), 77% of the world’s islands would face this dramatic scenario. Furthermore, most large islands harboring the highest number of threatened vertebrates are found on this critical situation (low protection and high human modification). Based on the analysis of these conservation scenarios, we identified potential priority islands that provide opportunities to improve island conservation worldwide. The mbest opportunities are located in 58 islands with a low level of protection and human modification, which harbor more than 5 threatened vertebrates’ species and are located in different regions of the world.

Integrated spatial model based evaluation methodology for optimal invasive species management: common ragweed in the Republic of Korea

Invasive species have become a global problem owing to their wide-ranging adverse effects. With intensifying climate change and artificial impacts (human-mediated disturbances), which exacerbate the adverse effects of invasive species, there is an urgent need to implement strategies for the management of these species. Various removal policies have been implemented globally to manage the common ragweed (Ambrosia artemisiifolia var. elatior (L.,) Decs) owing to its high tendency to ‘spread’. Several studies on the control method, application of spatial perspective, and optimization have been conducted to establish and evaluate management strategies using different spatial models. Although each of these methods is essential for improving control efficiency, an integrated form of study is needed to determine the practicality of various policies. In this study, we developed an integrated spatial model using the species distribution model BIOMOD2, land change model LCM, dispersal model MigClim, and optimization model prioritizr, to construct an evaluation methodology. For modelling an optimal invasive species removal policy under climate change and human-mediated disturbances (2011–2079), we created two strategies from a spatial perspective, outside-in and inside-out, with the former entailing removal from the low-density outliers to the high-density centre of the colonized area and the latter processing in the opposite direction. The optimal removal sites for each strategy were set for each removal rate. Subsequently, a novel index, ‘removal effect index’, was proposed for the evaluation, in time series. The results indicate that the removal effect of the outside-in strategy was more effective, and the newly dispersed sites were efficiently removed. Furthermore, it was verified that with the implementation of the outside-in strategy having a removal rate of 65% by the 2070s, the species would be completely eradicated. Thus, this study is expected to help improve the efficiency of policy implementation for invasive species.

Historical, contemporary, and future perspectives on a coupled social–ecological system in a changing world: Canada’s historic Rideau Canal

Anthropogenic waterways and canal systems have been part of the cultural and natural landscape for thousands for years. As of the late 20th century, more than 63 000 km of canals exist worldwide as transport routes for navigation, many with barriers (e.g., locks, dams) that fragment the system and decrease connectivity. Fragmentation alone can have negative implications for freshwater biodiversity; by isolating populations and communities, other human-mediated disturbances associated with canals like poor water quality and invasive species can exacerbate these negative effects. As such, the capacity of these interconnected freshwater systems to support biodiversity is continuously degrading at a global level. One critical, highly complex issue that unites canals worldwide is the challenge of governing these systems in a holistic, unified way to both protect biodiversity and preserve historical elements. Managing historic canals involves multiple objectives across many agencies and stakeholders, often with different or conflicting objectives. Here, we use the Rideau Canal, a UNESCO World Heritage Site and National Historic Site of Canada, as a case study to demonstrate the importance of considering canals as social–ecological systems for effective and efficient governance. Historic canals are integrated systems of both humans (social) and the environment (ecological), linked by mutual feedbacks and coevolution, and must be managed as such to achieve conservation goals while maintaining commemorative integrity. We discuss the history of the Rideau Canal and its current governance, biodiversity in the waterway, different threats and issues (user conflicts, aquatic pollution, shoreline development, water management, species at risk, and invasive species), and conclude by outlining ways to address the challenges of managing it as a coupled social–ecological system. We present different research needs and opportunities that would enable better management, though above all, we propose a shift from the current governance structure — which at best can be considered “patchwork” — to a coordinated, multi-scalar and multi-stakeholder governance regime such that the Rideau Canal can be maintained for its historical integrity without compromising biodiversity conservation. Given that canals are now pervasive worldwide, this article is not only topical to the Rideau Canal, but also to other waterways in Canada and beyond.

Effects of dam construction and fish invasion on the species, functional and phylogenetic diversity of fish assemblages in the Yellow River Basin

An understanding of the consequences of human-mediated disturbances from multi-facet diversity (i.e. species, functional and phylogenetic) perspectives is of great significance in biodiversity assessment and conservation planning. Most previous studies have concentrated on anthropogenic effects on species diversity in the Yellow River Basin (YRB) in China, but information on anthropogenic effects on phylogenetic and functional facets is still pending. Here, we identified the temporal changes in species, functional, and phylogenetic alpha diversity of fish assemblages in 18 reaches (i.e. 15 mainstream reaches and 3 tributaries) of the YRB under the background of long-term cascade hydropower construction and widespread introduction of non-native fish species. The results showed that native fishes experienced a sharp decline through time, with an average of 25.6 (extirpation rate 46.7%) native species extirpated per sub-region, and 89 of 182 (48.9%) native species extirpated across the whole basin during the period considered. However, the number of non-native fish species substantially increased, with an average increase of 8.6 species (invasion rate 26.9%) per sub-region. Furthermore, the percentage of non-native species showed a significant unimodal relationship with average altitude, with highest invasion rates (ca. 70%) in upstream reaches. The extirpation rate was negatively related to altitude, increasing from upstream to downstream reaches. Interestingly, the functional diversity indices (FEve, FDiv, FDis, RaoQ) and phylogenetic diversity indices (Δ+ and Λ+) of the entire fish fauna significantly increased through time, whereas these indices based on native fish fauna only did not change. Such increases in functional and phylogenetic diversities were mainly triggered by introductions of non-native species, which were functionally distinct and phylogenetically distant from native species, and extirpation of congeneric endemic species. In general, the present study revealed anthropogenic impacts on the multi-faceted diversity of fish assemblages in a large river and highlighted the negative effects of cascaded hydropower developments and non-native fish invasions on native fish. Moreover, evaluating the responses of multi-faceted diversity to anthropogenic disturbances is a suitable means to understand assemblage reorganization and to assess how such impacts lead to the decline of biodiversity. The complementary information derived from using the multi-faceted diversity approach indicate functional and phylogenetic diversity measures could be implemented in biodiversity planning in the sediment-laden and ecologically important Yellow River Basin.

Population genetics of wild and captive Trachemysvenusta (Gray, 1856) (Reptilia: Emydidae) in the Usumacinta river basin in Mexico.

The Mesoamerican slider Trachemysvenusta is endemic to Central America and Southern Mexico. Several human-mediated disturbances, including habitat degradation and illegal hunting for food, have impacted its populations along the Usumacinta river basin. The extent to which these disturbances have affected the genetic diversity and population structure of T. venusta inhabiting the basin remains unresolved. To this end, we analyzed eight microsatellite markers in five wild populations of T. venusta from the middle and lower reaches of the basin as well as one captive population. Our results show high levels of genetic diversity for all analyzed populations, low F ST values, high gene flow and no genetic structure, indicating an absence of genetic differentiation across sites and, thus, a single panmictic population for the basin. Evidence of a genetic bottleneck was observed in two of the wild populations (and the captive one), indicating some impact from disturbances, whether from poaching or habitat fragmentation, despite the seemingly high connectivity of most populations. Results are discussed in terms of the relative importance of genetic parameters for the conservation of T. venusta, particularly in light of the importance of demographic stochasticity in local conditions undergoing rapid changes.

Attenuated phenotypic responses of lizard morphology to logging and fire-related forest disturbance

Animals that face natural and human-mediated landscape disturbance processes can demonstrate different modalities of phenotypic variation to influence local population persistence. Differences in the frequency and pervasiveness of environmental variation can cause an individual’s phenotype to demonstrate either directional plasticity (i.e., environmental matching), canalization, or increased trait variance. Furthermore, how important a trait’s influence is on fitness can further mediate the nature of phenotypic outcomes to environmental variation. We explored the effects of multi-decadal chronosequences of logging and fire-related forest disturbance on morphological variation of the generalist lizard species, the Yellow-bellied water skink (Eulamprus heatwolei) in Southern Australia. There was evidence that both logging and fire-related disturbance could influence multiple elements of vegetation structure that would construe a major source of environmental variation for lizards. Nevertheless, neither logging nor fire-related disturbance effects resulted in significant differences in lizard morphological traits. However, there was evidence that years post-fire disturbance was associated with a modest but significant increase in a measure of lizard morphological variance. For the most part, we suggest that lizards exhibit canalization in their morphological responses to disturbance related environmental variation. In forests ecosystems with complex temporal and spatial regimes of environmental variation, canalization of lizard morphology could be expected to ensure phenotypic stability within or across generations to favor geometric, over arithmetic, fitness.

Population Genetic Structure and Natural Establishment of Hybrids Between Sarracenia flava and Sarracenia minor in Francis Marion National Forest

We assessed population genetic structure and rate of hybridization in Sarracenia flava and S. minor in Francis Marion National Forest. The forest has an abundance of potential habitat for our study species and has suffered less human mediated disturbance than much of the county's longleaf pine savanna and wet pine savanna ecosystems. We examined 63 S. flava and 62 S. minor individuals, as well as one hybrid across a 486.02 km2 study site. We used eight nuclear microsatellite loci and one non-coding chloroplast marker to assess population genetic structure and describe the parentage of the hybrid. We found relatively little population genetic structure across many distinct field sites, even when those sites were separated by unsuitable habitat. In very small populations surviving in shrub-dominated longleaf pine savanna, genetic divergence was greater than in larger populations with more suitable habitat. The single hybrid discovered was an F1 hybrid for which S. flava served as the maternal parent. We found no signs of introgression. We hope that these data can help inform conservation decisions regarding Sarracenia species, as the low genetic structure seems to suggest a high degree of connectivity between geographically distinct populations of plants.

Revegetation technique changes root mycorrhizal colonisation and root fungal communities: the advantage of direct seeding over transplanting tube-stock in riparian ecosystems

Riparian ecosystems are among the most degraded worldwide as they are subject to a range of human-mediated disturbances at different scales. As riparian vegetation plays a key role in maintaining waterway and landscape health, restoration often focuses on promoting riparian vegetation re-establishment. The role of below-ground processes and agents in the process of revegetation is often overlooked even though agents like mycorrhizal fungi enhance seedling establishment and plant growth. In this study we aimed to understand whether colonisation by local mycorrhizal fungi can be advantageous to the early phases of plant establishment during revegetation, whether revegetation technique influences the extent of this potential colonisation, and has the potential to enhance revegetation outcomes. We examined mycorrhizal colonisation rate and species composition of root fungal communities in direct seeded and tube-stock plants and compared them with local native vegetation in a retarding basin in Victoria, Australia, then modelled the relationship between root fungal community attributes and plant size. Results indicate that revegetation technique influenced the colonisation rate, diversity and composition of root fungal communities. Moreover, greater fungal diversity and greater similarity of fungal communities to the mycobiota of native vegetation were positively related with growth of seeded plants but showed negative or little relationship to size of tube-stock plants. High colonisation rates of plant species studied, and relationships between fungal community characteristics and plant growth of seeded plants provide the first evidence of the potential importance of mycorrhizal associations for these plant species in a revegetation context.

Resilience of Octocoral Forests to Catastrophic Storms

After centuries of human-mediated disturbances, Caribbean reef communities are vastly different from those described in the 1950s. Many are functionally dominated by macroalgae, but this community state represents only one of several possibilities into which present-day coral reefs can transition. Octocorals have always been abundant on Caribbean reefs, but increases in their abundance over the last few decades suggest that arborescent octocorals have the potential to expand their populations on reefs that hitherto had been dominated by scleractinians. Here we show that octocoral-dominated communities at three sites on the fringing reefs of St. John, US Virgin Islands, were resilient to the effects of two Category 5 hurricanes in 2017. We describe the dynamics of octocoral communities over five years at three sites on shallow reefs (~9-m depth), and test for the effects of Hurricanes Irma and Maria. The hurricanes depressed the densities of juvenile and adult octocoral colonies as much as 47%. However, there were only weak effects on species richness and the relative abundances of the octocoral species. The hurricanes did not alter patterns of spatial variability in octocoral community structure that existed among sites prior to the storms. The density of octocoral recruits (individuals ≤ 5 cm high) was reduced in the year following the hurricanes, mainly due to a decline in abundance of recruits <0.5 cm, but returned to pre-storm densities in 2019. Persistently high octocoral recruitment provides a mechanism supporting ecological resilience of these communities. Continuing environmental degradation is a threat to all tropical marine communities, but the reefs of St. John illustrate how “octocoral forests” can persist as the structurally dominant community on Caribbean reefs.

Toward an Historical Agroecology: an academic approach in which time and space matter

ABSTRACT We pose that Agroecology, which is already a hybrid science, is further overcoming disciplinary isolation and stagnation through explicit processes of interdisciplinary recombination, in what might be termed “second generation hybridization”. We refer to the intellectual contact zone of Agroecology – mainly with Cultural Geography, Historical Ecology, Archeology, Ecological Anthropology, and Ethnoecology – as “Historical Agroecology”. We discuss the following five theoretical methodological foundations of our proposal toward an Historical Agroecology: (1) regional agroecological histories, (2) agroecological landscapes as palimpsests: human-mediated disturbances and their cumulative effects, (3) alpha and beta as agrobiodiversity on the table: manifestations of human niche construction, (4) agroecological ethos as landscapes of knowledge, and (5) infrapolitics and collective action as other forms of agroecological resistance aside from social movements. We illustrate these points through case studies based on our research in peasant communities of the Maya lowlands in the Mexican states of Yucatan, Chiapas, and Campeche. We conclude by reflecting on the need to further develop historical agroecological perspectives in those regions with agricultural systems that have resulted from profound diachronic legacies that are spatially rooted in broad geographical areas.

On the Need to Differentiate the Temporal Trajectories of Ecosystem Structure and Functions in Restoration Programs

Potential time lags between human-mediated disturbances and the subsequent responses of ecosystems are critical for planning and implementing conservation and restoration actions. In this context, decoupling between the temporal trajectories of ecosystems structure and functions is particularly critical. Here, we stand out the need to differentiate the temporal trajectories of ecosystem structure and functions to be considered in ecological restoration programs. In cases when ecosystem functions persist after the degradation of the ecosystem structure, and when functions do not recover at the same rate as structure, some kind of ecosystem functioning credits or debts can occur. In other situations, an ongoing loss of the ecosystem function can occur even in the absence of further disturbance. Ecosystem restoration outcomes could be optimized in regions with ecosystem functioning credit, since mitigating the decline in functioning will be more efficient than recovering functions in highly degraded conditions. Ecological restoration programs should not only focus on structure-derived indicators but they should also consider the dynamics of ecosystem functions to guide land-planning decision-making.

Spatial ecology of copperhead snakes (Agkistrodon contortrix) in response to urban park trails

Abstract Urban forests and parks are important for recreation and may serve as a natural corridor for commuters. The consequences of human-mediated disturbance in natural areas are documented for avian and mammalian species. Less is known about the consequences of human disturbance on reptile species, specifically snakes, residing in natural refuges within the urban matrix. Thus, we examined the spatial activity of copperheads (Agkistrodon contortrix) in regard to pedestrian trails within an urban forest. We used radio telemetry to track snakes during the active season and estimated distances moved in between relocations, distances to the nearest trail and home range size for individuals. We found sex and season, but not distance to the nearest trail, affected the distance snakes moved. In addition, we observed a weak, positive relationship between home range size and average distance to the trail. Sex, season and body condition did not explain snake distance to the trail, but individual patterns were variable for snakes compared to random locations generated from snake relocations. Our study indicates copperheads may be tolerant of low-level human disturbances found in an urban forest. Further work should be done to quantify levels of disturbance, such as trail use, and compare the behavior of reptiles across urban park types and locations.

Effects of linear features on resource selection and movement rates of wood bison (Bison bison athabascae)

Human-mediated disturbances can lead to novel environmental features that can affect native biota beyond simple habitat loss. In boreal forests of western Canada, linear features (LFs; e.g., pipelines, seismic lines, and roads) are known to alter behaviour, movements, and interactions among species. Understanding LF impacts on native species has therefore been a management priority. Here, we investigate how LFs affect the spatial behaviour of wood bison (Bison bison athabascae Rhoads, 1898), which are designated as “threatened” in Canada. Using data collected from the Ronald Lake population in northeastern Alberta, we assessed how LFs influenced habitat selection and movement of bison by testing support among three hypotheses explaining whether LFs (i) increased forage availability, (ii) enhanced movement efficiency, or (iii) increased predation risk. Results supported the movement efficiency hypothesis as bison were generally ambivalent toward LFs, showing weak selection or avoidance depending on land-cover type, but moved slightly faster when on them. These findings contrast with avoidance behaviours reported for sympatric woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)), which are also “threatened.” Our results should inform critical habitat decisions for wood bison, but we caution that further research is needed to understand the effects of LFs on bison demography.