Landscape Ecology最新文献

Context

Global change, including land-use change and habitat degradation, has led to a decline in biodiversity, more so in freshwater than in terrestrial ecosystems. However, the research on freshwaters lags behind terrestrial and marine studies, highlighting the need for innovative approaches to comprehend freshwater biodiversity.

Objectives

We investigated patterns in the relationships between biotic uniqueness and abiotic environmental uniqueness in drainage basins worldwide.

Methods

We compiled high-quality data on aquatic insects (mayflies, stoneflies, and caddisflies at genus-level) from 42 drainage basins spanning four continents. Within each basin we calculated biotic uniqueness (local contribution to beta diversity, LCBD) of aquatic insect assemblages, and four types of abiotic uniqueness (local contribution to environmental heterogeneity, LCEH), categorized into upstream land cover, chemical soil properties, stream site landscape position, and climate. A mixed-effects meta-regression was performed across basins to examine variations in the strength of the LCBD-LCEH relationship in terms of latitude, human footprint, and major continental regions (the Americas versus Eurasia).

Results

On average, relationships between LCBD and LCEH were weak. However, the strength and direction of the relationship varied among the drainage basins. Latitude, human footprint index, or continental location did not explain significant variation in the strength of the LCBD-LCEH relationship.

Conclusions

We detected strong context dependence in the LCBD-LCEH relationship across the drainage basins. Varying environmental conditions and gradient lengths across drainage basins, land-use change, historical contingencies, and stochastic factors may explain these findings. This context dependence underscores the need for basin-specific management practices to protect the biodiversity of riverine systems.

Abstract

Context

Large-scale natural disturbances are crucial drivers of ecosystem function and composition for many forested ecosystems. In the last century, the prevalence of anthropogenic disturbances has increased across Canada’s boreal forest. Habitat disturbance from timber harvest and wildfire is linked to declines of boreal species, including woodland caribou (Rangifer tarandus caribou).

Objectives

We tested how disturbances influenced the recovery trajectory of ecological indicators of timber, biodiversity, and wildlife habitat through time following timber harvest and wildfire across the boreal forest of Alberta, Canada.

Methods

During 2021 and 2022, we collected field data from 251 timber harvested and 264 burned stands (0–40 years since disturbance), as well as 256 older forest stands used by caribou (> 40 years since disturbance). Field data included metrics of stand attributes (e.g., basal area, stems per hectare), coarse woody debris (CWD), and abundance of forage for caribou, moose (Alces americanus), and bears (black bear: Ursus americanus, grizzly bear: Ursus arctos).

Results

Basal area of trees and stems per hectare recovered more quickly in timber harvest sites when compared to wildfire sites, but as time since disturbance increased there were no differences in these attributes among timber harvest, wildfire, and caribou use sites. CWD was greatest in recently burned sites, but declined over time to be similar in quantity as in harvested stands and older forest stands. Terrestrial lichens, important forage for caribou, were most abundant in the older caribou use sites, whereas forage for moose and bears, including shrubs, was most abundant in younger timber harvest and wildfire sites.

Conclusions

Our results demonstrate that timber harvesting may result in a quicker development of timber volume when compared to wildfire. However, this anthropogenic disturbance is less advantageous for the development of caribou habitat.

Context

Mongolian Plateau is one of the largest contingent arid and semi-arid regions of the world. Rivers on the plateau provide vital water for millions of indigenous Mongolian people and numerous endangered wildlife, but are increasingly disturbed by climate change and human activities. Yet, long-term changes in river runoff across the plateau remain poorly studied due to data unavailability.

Objectives

This study aimed to analyze the temporal trends in gauged river runoff on the Mongolian Plateau, identify drivers of the observed changes, and evaluate CMIP6 models' performance in simulating historical runoff changes across the plateau.

Methods

We compiled possibly the largest database of long-term (20 - 71 years) river runoff for the plateau comprising measurements over 30 major rivers. Statistical analyses were conducted to assess trends in river runoff and correlations between runoff and climatic variables. Additionally, we applied the Budyko curve framework to identify the influence of human activities on river runoff in specific basins. Furthermore, we compared ground-measured runoff data with simulations from CMIP6 models to evaluate the ability of CMIP6 models to replicate runoff dynamics in typical arid and semi-arid regions.

Results

We observed pervasive and abrupt reduction in runoff in 21 out of the 30 rivers within 5 years before or after the year of 2000. Variations in river runoff were most significantly caused by changes in total precipitation (TP). In particular, 27 rivers experienced abrupt TP changes around 2000, and there was a significant positive correlation between annual fluctuations in TP and river runoff for 18 rivers. In addition to climate factors, the influence of human activities was identified in certain basins. The CMIP6 simulations failed to capture the abrupt changes in runoff occurred pervasively across the plateau around 2000.

Conclusions

Around 2000, major rivers on the Mongolian Plateau, especially in Inner Mongolia, experienced runoff declines, primarily due to TP changes. Human activities like dam construction and water diversion further influenced local runoff. CMIP6 historical runoff simulations were inaccurate across the plateau, highlighting the difficulty of simulating river runoff in this critical region. Our study could contribute to a more comprehensive understanding of the water resource changes on the Mongolian Plateau, with direct implications for enhancing ecological conservation and management practice.

Context

Passive habitat rewilding after rural abandonment can affect wildlife differently depending on the type of habitats that it generates.

Objective

Evaluate and compare the effects of two alternative vegetation trajectories that occur through passive habitat rewilding in Mediterranean ecotone areas (crop-scrub and crop-pine forest transitions) on the long-term population dynamics of animal species.

Methods

We used the spur-thighed tortoise (Testudo graeca), a characteristic long-lived species of cultural landscapes, as study species. We applied a spatially explicit and individual-based model (STEPLAND) to simulate the movement and demographic processes in a long-term period, by comparing an “impact scenario” (i.e., historical land-use changes) to a “control scenario” (no land-use changes).

Results

The two landscape scenarios resulted in different population trends. In the crop-scrub scenarios (control and impact), population densities increased similarly over time. However, the crop-pine forest scenario negatively affected population density throughout the simulation period, and showed a time-lag response of three decades. The extinction risk was 55% with a time-lag response of approximately 110 years.

Conclusions

Our study highlights the need to analyse the legacy effects on long-lived ectotherms, using them as a proxy to understand the future effects of dynamic landscapes created by “passive habitat rewilding”. Our results showed how traditional agriculture in Mediterranean ecotone areas may generate “ecotone effects” (i.e. increase in demographical parameters), but also population extinction on long-lived ectotherms. Therefore, we consider it relevant to maintain traditional agricultural areas in Mediterranean landscapes, especially in ecotone areas associated with pine forests (generating mosaics with open habitats).

Abstract

Context

Road expansion has raised concerns regarding road effects on wildlife and ecosystems within the landscape. Salamanders, critical ecosystem components and bioindicators, are vulnerable to road impacts due to habitat loss, migrations, and reliance on stream health. Systemic reviews considering the effects of different road types on salamanders are lacking.

Objectives

We summarize 155 studies of road effects on salamanders, including paved, unpaved, and logging roads, hiking trails, railroads, and powerlines. We examine trends in road type, study area, and impacts on salamanders; summarize current knowledge; and identify knowledge gaps.

Methods

We used Web of Science for literature searches, completed in January 2023. We reviewed and summarized papers and used Chi-squared tests to explore patterns in research efforts, research gaps, and impacts on salamanders.

Review

Roads had negative effects on salamanders through direct mortality, damaging habitat, and fragmenting populations. Traffic and wetland proximity increased negative impacts in some studies; abandoned logging roads showed negative effects. Positive effects were limited to habitat creation along roads. Habitat creation and under-road tunnels with drift fencing were effective mitigation strategies. Non-passenger vehicle roads were critically understudied, as were mitigation strategies such as bucket brigades and habitat creation along roads.

Conclusions

With road networks expanding and salamander populations declining, managers must account for road effects at landscape scales. The effects of non-paved roads on salamanders are poorly understood but critically important as such roads are frequently located in natural areas. Managers should incorporate mitigation strategies and work to reduce road impacts on vulnerable wildlife.

Context

Managing landscapes to increase multiple services provision in search of higher agricultural yield can be an alternative to agricultural intensification. Nonetheless, to properly guide management, we need to better understand how landscape structure affects multiple services at different scales.

Objectives

Focused on synergies and trade-offs in real-world landscapes, we investigated how and at which scale landscape features related to the supply, demand and flow of services act as a common driver of pollination and pest control in coffee plantations.

Methods

Considering landscapes in an important coffee-producing region in Brazil, we tested the effects of forest and coffee cover, distance to forest, forest-coffee edge density and coffee edge diversity at multiple scales on pollination and pest control by birds, bats and ants.

Results

Coffee edge diversity (number of land uses in contact with coffee) was an important driver of pollination and pest control, being consistently relevant at local scales (up to 300 m). However, services were also affected by other landscape features and the ‘scale of effect’ of these relationships varied. Additionally, results show the complex nature of pest control once the direction of effect revealed services and disservices.

Conclusions

Besides reinforcing the importance of known landscape effects, this study adds to previous studies by showcasing the relevance of diverse land uses around coffee crops as a common driver of pollination and pest control provision by different species. Moreover, we highlight how understanding the combined local and landscape effects may aid in offsetting disservices and tackling the variety of ‘scales of effect’ found.