Changes In Landscape Composition Research Articles

Landscape metrics as a framework to measure the effect of landscape structure on the spread of invasive insect species

With accelerated land-use change throughout the world, increased understanding of the relative effects of landscape composition and configuration on biological system and bioinvasion in particular, is needed to design effective management strategies. However, this topic is poorly understood in part because empirical studies often fail to account for large gradients of habitat complexity and offer insufficient or even no replication across habitats. The aim of this study was to disentangle the independent and interactive effects of landscape composition and landscape configuration on the establishment and spread of invasive insect species. We explore a spatially-explicit, mechanistic modeling framework that allows for systematic investigation of the impact of changes in landscape composition and landscape configuration on establishment and spread of invasive insect species. Landscape metrics are used as an indicators of invasive insect establishment and spread. We showed that the presence of an Allee effect leads to a balance between the effectiveness of spread and invasion success. Spread is maximized at an intermediate dispersal level and inhibited at both low and high levels of dispersal. The landscape, by either increasing or mitigating the dispersal abilities of a species, can lead to a rate of spread under a dispersal threshold for which density and spread is at the highest. Our study proposes that change in landscape structure is an additional explanation of the highly variable spread dynamics observed in natural and anthropogenic landscapes. Consequently, a landscape-scale perspective could significantly improve spread risk assessment and the design of control or containment strategies.

Genetic consequences of landscape change for rare endemic plants – A case study of Rhinanthus osiliensis

During the last hundred years European landscapes have experienced an extensive change in structure including a substantial loss of wetland habitats. In the current study we examined the influence of landscape change and current landscape composition on the genetic diversity of Rhinanthus osiliensis, a very rare endemic plant with narrow distribution range restricted to calcareous spring and species-rich fens in western part of the island of Saaremaa, Estonia. We observed very high inbreeding in some study populations of R. osiliensis. Furthermore, bottleneck analysis revealed that in fact all examined populations had experienced a severe decline in population size in the recent past. This result indicates that the high levels of inbreeding in R. osiliensis are not only the consequence of the mixed mating system common in this species, but may at least partly be attributed to habitat loss. Indeed, the analysis of landscape change revealed a substantial decrease in the area of mires during the last century in all study landscapes. Unexpectedly, current habitat availability did not influence the measures of genetic diversity. Nevertheless, the allelic richness of R. osiliensis was negatively affected by the amount of forests, which may have acted as a barrier for pollen flow in this insect-pollinated plant. We conclude that the populations of habitat-specialist rare plants such as R. osiliensis are endangered not only by the loss of habitats but also by other changes in landscape composition, e.g. afforestation, leading to strong declines in population size accompanied by genetic bottlenecks, decreased genetic diversity and high inbreeding.

The effects of landscape history and time-lags on plant invasion in Mediterranean coastal habitats

Human-driven landscape changes may promote plant invasions by increasing propagule pressure and providing favourable conditions for non-native species to establish and spread. The increase in invasion levels might not be immediate but rather exhibit a time-lag (i.e. invasion debt). Moreover, the relationship between invasion and landscape history (i.e. changes in landscape composition) might be extremely complex as it might also include extinction debts of invasive species currently in regression. In order to understand the effect of landscape history on plant invasion, we studied the invasion level in coastal plant communities affected by intense human-driven landscape alteration in the last 50 years. We identified all non-native plant species within 809 grid cells (250 × 250 m) along ~500 km of the Spanish SW coast. We tested the association of (1) non-native richness conditional on the overall presence of non-natives (at least one species), and (2) the occurrence of the most frequent non-native species, with the percentage of human land-cover categories in 1956, 1991 and 2007 using a multimodel inference approach. We used these models to project future invasion patterns in the region. We found non-native richness to be more associated with land-cover variables in 1956 than in 2007, suggesting the existence of an invasion debt, but not for the overall presence of non-natives. For most frequent species, the effects of past landscape alteration depended on the introduction pathway and the region of origin. Species used in agriculture were more related to past cropland area, while most of the species used in gardening or forestry showed higher affinity for recently altered areas. These results highlight the relevance of the species’ introduction history and landscape history in assessing future long-term invasion trends.

Is the lesser horseshoe bat (Rhinolophus hipposideros) exposed to causes that may have contributed to its decline? A non-invasive approach

While the lesser horseshoe bat (Rhinolophus hipposideros) was common in most western and Central Europe, this species endured a dramatic decline in the 1950s–1970s. The causes are thought to comprise the extensive spread of chemical pollutants affecting both bat and prey populations, changes in landscape composition and structure leading to population fragmentation or roost deterioration, and infectious diseases. While lesser horseshoe bat populations recently increased after nearly thirty years of decline in the Franche-Comté region (eastern France), it is unclear whether bats are currently confronted with causes that may have contributed to former demographic disturbances. Although stressors are generally studied separately, we simultaneously measured several variables directly or indirectly reflecting the supposed causes of bat decline: availability of woodland habitats around bat roosts, genetic differentiation amongst colonies, and exposure to chemical pollutants and to a protozoan parasite, Eimeria hessei. Twenty maternity colonies were sampled using a non-invasive approach based on droppings. Maternity roosts were located in buildings mainly surrounded by woodland and shrubland (48% of a 2500 m radius buffer around the colonies), which are preferentially used by the lesser horseshoe bat as foraging areas. Low genetic differentiation (FST=0.023–0.028, D=0.076–0.097) and no genetic clusters were found among the 20 sampled colonies, in which 449 individuals were distinguished over two sampling sessions (2010 and 2011). This suggests that no obvious physical barrier acts as a constraint with respect to gene flow, and we conclude that all individuals sampled belong to a unique non-fragmented population. Among the 66 chemical substances measured in bat droppings, the insecticides endosulfan alpha (0.035μg∕gdm) and lindane (from 0.013 to 0.112μg∕gdm) were the only organic compounds found at detectable concentrations in one and 7 colonies, respectively. Fourteen metals were measured in the guano. Metal concentrations were lower than or of the same order of magnitude as concentrations reported in bats in the literature. The overall faecal prevalence of E. hessei was 42% (range: 0%–80%) and did not differ between the two sampling sessions. Faecal prevalence was not related to lindane concentrations in droppings. Despite the low concentrations of metals, a positive relationship was found between cadmium and zinc concentrations and E. hessei faecal prevalence. Although it is difficult to conclude on the risks of adverse effects due to the lack of both toxicological references and knowledge on E. hessei pathogenicity, this study stresses out the interest of systemic approaches in the study of ecology of wildlife species, especially via the investigation of multiple exposures.

Land tenure and landscape change: a comparison of public-private lands in the southern High Plains

Long-term drought in the southern Great Plains increases the vulnerability of coupled human-environment systems at a variety of scales. Developing better understandings of the dynamics at regional scales will become increasingly important as long-established land-use regimes break down in the face of climate change, resource depletion, and evolving governance. To demonstrate differential vulnerability during drought periods, this study hypothesized that observed increases in woody vegetation in grasslands would vary across land-tenure regimes. We argue that differences in State Trust Land governance, in part, lead to differential land management practices that contribute to landscape change. The study area encompasses adjacent counties, Cimarron County in Oklahoma and Union County in New Mexico, with similar climate variability and agricultural economies. We analyzed National Land Cover Database (NLCD) land-cover maps from 1992 and 2011 to assess changes in landscape composition and structure between 1992 and 2011. During both years under consideration, each county in the study region, across various land-tenure regimes, was dominated by herbaceous vegetation. However, there were changes in both composition and structure across the whole study area, in particular losses of herbaceous vegetation and increases in woody vegetation. The greatest gains in woody vegetation occurred in State Trust Lands of Cimarron County. Overall, the data suggest a fragmentation of herbaceous vegetation and a coalescing of shrubland patches. Research about the influence of land tenure on land management decisions, specifically the role of State Trust Land leases in overgrazing, informs the broader context of drought management in the southern Great Plains. Recommendations include continued research to highlight the specific mechanisms of land-tenure governance that drive landscape change.

A Holistic Landscape Description Reveals That Landscape Configuration Changes More over Time than Composition: Implications for Landscape Ecology Studies.

BackgroundSpace-for-time substitution—that is, the assumption that spatial variations of a system can explain and predict the effect of temporal variations—is widely used in ecology. However, it is questionable whether it can validly be used to explain changes in biodiversity over time in response to land-cover changes.HypothesisHere, we hypothesize that different temporal vs spatial trajectories of landscape composition and configuration may limit space-for-time substitution in landscape ecology. Land-cover conversion changes not just the surface areas given over to particular types of land cover, but also affects isolation, patch size and heterogeneity. This means that a small change in land cover over time may have only minor repercussions on landscape composition but potentially major consequences for landscape configuration.MethodsUsing land-cover maps of the Paris region for 1982 and 2003, we made a holistic description of the landscape disentangling landscape composition from configuration. After controlling for spatial variations, we analyzed and compared the amplitudes of changes in landscape composition and configuration over time.ResultsFor comparable spatial variations, landscape configuration varied more than twice as much as composition over time. Temporal changes in composition and configuration were not always spatially matched.SignificanceThe fact that landscape composition and configuration do not vary equally in space and time calls into question the use of space-for-time substitution in landscape ecology studies. The instability of landscapes over time appears to be attributable to configurational changes in the main. This may go some way to explaining why the landscape variables that account for changes over time in biodiversity are not the same ones that account for the spatial distribution of biodiversity.

Mediterranean fire regime effects on pine-oak forest landscape mosaics under global change in NE Spain

Afforestation after land abandonment and the occurrence of large fires have significantly altered the composition of pine-oak ecosystems in the Mediterranean since 1950s, the latter favouring the prevalence of oak forests and shrublands to that of pine forests. Nevertheless, our ability to integrate the processes driving these changes in modelling tools and to project them under future global change scenarios is scarce. This study aims at investigating how Mediterranean forest landscape composition and seral stages may be affected by mid-term changes in fire regime and climate. Taking Catalonia (NE Spain) as study area, we predicted yearly changes in forest landscape composition using the MEDFIRE model which allows assessing the effects of different fire regimes on landscape dynamics such as post-fire regeneration and afforestation. We considered three climatic treatments based on observed and projected climate, two fire regimes largely differing in the amount of area burnt and the number of large fires, and two fire suppression strategies. While projected afforestation continued to increase forest cover in the 2050 horizon, a climate-related harsher fire regime (higher amounts of area burnt) accelerated a shift towards landscapes progressively dominated by oaks and shrublands, thus precluding general forest maturation. Fire-sensitive pine species contributed to net forest cover loss in the worst scenarios. An active fire suppression strategy partially compensated the effects of a climate-related harsher fire regime on pine forest loss and rejuvenation, whereas variability in climate projections weakly affected spatial fire allocation and afforestation. Our results highlight the need to explicitly incorporate fire suppression strategies in forest landscape composition forecasts in the Mediterranean. At mid-term, large-scale afforestation, post-fire forest rejuvenation and landscape composition changes may alter forest ecosystem functioning and potentially interact with fire suppression planning.

Tree cover mediates the effect on rapeseed leaf damage of excluding predatory arthropods, but in an unexpected way

Birds and predatory arthropods are often implicated in pest control, but their relative impact and how this is mediated by variation in tree cover requires elucidation. We excluded birds and ground predatory arthropods from rapeseed plants in 2.5×1m plots in 26 homegardens in Ethiopia, leaving the same sized control plots. From six groups of plants in bird exclosure and control plots, respectively, three groups were excluded from ground predatory arthropods. Data on leaf damage were surveyed four times at weekly intervals. The tree cover and land-use composition within 100×100m surrounding each plots were recorded in the field and from a satellite image within 200 and 500m buffer zones. The results show that the mean leaf damage was higher on rapeseed plants from which predatory arthropods were excluded than on control plants. However, excluding birds had no or only a weak impact on leaf damage. The mean leaf damage within predatory arthropod exclosures decreased with increasing tree, forest and perennial cover but increased with increasing grazing land cover and annual crop cover, while on control plants it was low across the tree cover variation. This pattern may indicate the presence of a higher density of herbivores on rapeseed plants and also more predatory arthropods (i.e., to control them) in tree-poor homegardens compared to tree-rich homegardens. Hence, tree-poor homegardens in this landscape have sufficient habitat heterogeneity to support natural enemies to deliver significant pest control on rapeseed. Our results show that there was variation in the dynamics of pests and predatory arthropods across the tree cover variation, suggesting changes in landscape composition could affect the pest control services and the outcomes for local farmers.

Satellite monitoring of urbanization and environmental impacts—A comparison of Stockholm and Shanghai

This study investigates urbanization and its potential environmental consequences in Shanghai and Stockholm metropolitan areas over two decades. Changes in land use/land cover are estimated from support vector machine classifications of Landsat mosaics with grey-level co-occurrence matrix features. Landscape metrics are used to investigate changes in landscape composition and configuration and to draw preliminary conclusions about environmental impacts. Speed and magnitude of urbanization is calculated by urbanization indices and the resulting impacts on the environment are quantified by ecosystem services. Growth of urban areas and urban green spaces occurred at the expense of cropland in both regions. Alongside a decrease in natural land cover, urban areas increased by approximately 120% in Shanghai, nearly ten times as much as in Stockholm, where the most significant land cover change was a 12% urban expansion that mostly replaced agricultural areas. From the landscape metrics results, it appears that fragmentation in both study regions occurred mainly due to the growth of high density built-up areas in previously more natural/agricultural environments, while the expansion of low density built-up areas was for the most part in conjunction with pre-existing patches. Urban growth resulted in ecosystem service value losses of approximately 445 million US dollars in Shanghai, mostly due to the decrease in natural coastal wetlands while in Stockholm the value of ecosystem services changed very little. Total urban growth in Shanghai was 1768km2 and 100km2 in Stockholm. The developed methodology is considered a straight-forward low-cost globally applicable approach to quantitatively and qualitatively evaluate urban growth patterns that could help to address spatial, economic and ecological questions in urban and regional planning.

Changes in landscape composition of differently irrigated hay meadows in an arid mountain region

AbstractQuestionsDoes the recent change from traditional to sprinkler irrigation result in alterations in the surrounding landscape of species‐rich hay meadows in an arid Swiss mountain region? Are landscape composition and landscape heterogeneity important determinants of plant diversity in these meadows?LocationSouthwestern Switzerland.MethodsWe surveyed vascular plant species in six traditionally and six sprinkler‐irrigated hay meadows. Plant species were divided into grassland specialists and generalists. Individual landscape traits were assessed in circular areas with radii of 50 and 100 m around each meadow in a field survey. Aerial photographs were used to measure the percentage area covered by different habitat types in the present and prior to the installation of sprinklers at the same spatial scale as in the field surveys. The potential effects of irrigation technique and present‐day landscape features on the plant diversity and species composition of hay meadows were examined with GLM and NMDS.ResultsLandscape composition was more diverse for traditionally than for sprinkler‐irrigated meadows, but did not differ prior to the installation of sprinklers. Total plant species richness and the number of specialists were negatively affected by the distance to the closest haystack. Generalists were positively influenced by a variety of different small‐scale landscape traits in the surroundings, whereas the percentage area covered by woodland had a negative effect. Finally, hay meadows irrigated with sprinklers had an increased number of generalist plant species.ConclusionsThis study showed that the small‐scale surroundings, and to some extent the type of irrigation, are important for the conservation of plant diversity of these meadows. Furthermore, the study suggests that the installation of sprinklers was associated with a homogenization of the landscape, which facilitates land use. Extensive management should be promoted by compensation payments for farmers to prevent intensification.

An analysis of changes in the urban landscape composition and configuration in the Sancaktepe District of Istanbul Metropolitan City, Turkey using landscape metrics and satellite data

Changes in landscape composition and configuration patterns of Sancaktepe Municipal District in the Asian side of Istanbul Metropolitan City of Turkey were analysed using landscape metrics. Class-level and landscape-level metrics were calculated from the land cover/land use data using Patch Analyst, an extension in the Arc View GIS. The land cover/land use data were derived from classified satellite images of Landsat Thematic Mapper of 2002 and 2009 for Sancaktepe District. There was evidence of increase in agglomeration process of built-up patches as indicated by the increases in mean patch size, decrease in total edge and number of patches between 2002 and 2009. The urban expansion pattern experienced overall was not fragmented but concentrated due to infilling around existing patches. Changes in Area-Weighted Mean Shape Index and Area-Weighted Patch Fractal Dimension Index indicated that the physical shapes within built-up, forest and bareland areas were relatively complex and irregular. A conclusion is made in this study that spatial metrics are useful tools to describe the urban landscape composition and configuration in its various aspects and certain decisions whether to approve a specific development in urban planning could, for example, be based on some measures of urban growth form or pattern in terms of uniformity and irregularity, attributable to the dynamic processes of agglomeration and fragmentation of land cover/land use patches caused by urban expansion.

Is cork oak (Quercus suber L.) woodland loss driven by eucalyptus plantation? A case-study in southwestern Portugal

Mediterranean landscapes with open cork oak (Quercus suber L.) woodlands have recently experienced drastic changes in southwestern Portugal. Changes in agricultural activities, the traditional driver of the economy in this region, led to new land uses, such as long-term set aside (shrublands) and eucalyptus plantations. A study was conducted on the oak woodland landscape dynamics over a 50-year period (from 1958 to 2007) in order to assess the effect of different biophysical conditions on landscape spatial changes, and to identify the resilience of lanscape composition to different disturbances (e.g., socio-economic changes and wildfires). Land use changes over two consecutive periods (1958-1995 and 1995-2007) were inferred by spatial analysis of land cover data (aerial photographs) and related to landscape physical attributes (slope and soil type). A transition matrix of four vegetation land-cover classes was obtained, allowing the assessment of the landscape composition changes bewteen the two above periods. Results showed that lansdcape in 1958 was largely occupied by open farmland, with large patches of open oak woodlands on steep slopes surrounding watercourses. Open farmland and shrubland drastically declined from 1958 to 1995, while eucalyptus plantation exhibited a dramatic expansion. Although large areas of cork oak forest turned into eucalyptus plantation, the net loss of oak forest was low and counterbalanced by its increment on former open farmland. The occurrence of a wildfire in 2003 promoted a dramatic decrease in cork oak woodlands, which mostly turned into shrubland. However, shrubland may be considered “safe sites” for ecological succession, ensuring natural cork oak regeneration and the colonisation of neighboring areas.

Landscape composition influences pollinators and pollination services in perennial biofuel plantings

Biofuel cropping systems are considered a potential source of renewable energy and an integral component of a sustainable energy policy. The type of biofuel crop selected for production has the capacity to substantially alter landscape composition, affecting biodiversity conservation and ecosystem services. To understand how increasing production of perennial grasses for biofuels may affect pollinators and pollination services, we identified 20 agricultural fields that varied in their proportion of surrounding grassland cover. Bees and pollination services were measured at each site to determine how bee abundance, diversity, and community composition responded to increasing proportions of grassland, and to quantify how pollination services changed as the proportion of grassland increased in the landscape. Bees were collected from sentinel sunflowers, and pollination services were measured by comparing seed set from open and closed sunflowers at each site. Landscape composition had a significant effect on bee abundance, diversity, and community composition with a greater abundance of bees and a more diverse bee community found visiting flowers at sites with more of the surrounding landscape in perennial grassland. In contrast, the bee community in low grassland sites was dominated by Apis mellifera, suggesting that pollination in these landscapes may be more sensitive to declines in this species. Despite these differences, the level of sunflower pollination was similar across sites, even though the bee community responded to changes in landscape composition. Increasing grassland cover through the addition of perennial biofuel plantings would be expected to support a more diverse bee community and a greater abundance of bees, yielding reliable pollination services.

不同干扰背景下农业景观异质性——以巩义市为例

景观异质性包括景观组成和构型的异质性，而人为干扰是形成异质性景观的主要影响因素。以河南省巩义市为例，在以建成区、农田、丘陵和山地为主体的景观中各选取一个4km×4km的样区，采用移动窗口算法，以100、250、500、1000、1250m和1500m为移动窗口半径，借用蔓延度（CONT）和均匀度（SHEI）指数，分析了不同干扰背景下景观异质性的空间变化特征。结果表明：随着移动窗口半径的增大，各景观类型的蔓延度和均匀度指数的最大值逐渐递减，最小值逐渐递增（建成区除外）；建成区和农田景观蔓延度指数的平均值均大于丘陵和山地景观，均匀度指数的平均值则相反；4种类型景观的均匀度指数和蔓延度指数都呈显著相关关系，除建成区1000m及以上移动窗口半径外，<em>R</em>²都大于0.9；拟合曲线的<em>β</em>值基本呈递增趋势。文中对于人为干扰强度的差异性和景观异质性的尺度依赖性分析，为构建合理的景观格局提供了理论依据。;Landscape heterogeneity consists of landscape composition and configuration, while human disturbance is one of the main factors affecting landscape heterogeneity. So far there are few of studies on landscape heterogeneity under the different disturbances by using moving window. Selecting Gongyi City of Henan Province as the study area, this paper is aimed to reveal the characteristics of the agro-landscape heterogeneity under the different intensity of human disturbance. We set up a 4km×4km sample area in urban area, farmland, hilly and mountains respectively. By using moving window, we count the contagion index and the evenness index at landscape level. The moving window radius divided into 100m, 250m, 500m, 1000m, 1250m and 1500m. In order to reflect the features of landscape composition and landscape configuration on multiple scales, we calculate the contagion index and the evenness index in the moving windows radius. Meanwhile the correlation of the two indexes is also studied by curve estimate. The <em>β</em> of the fitted curve illustrates that the contagion index changes along with the evenness index on the contrary, that is to say, landscape composition changes consistent with landscape configuration in the opposite direction. The study results are as follows: 1) Along with increasing of the moving radius, the maximum of contagion index and evenness index decline gradually in the four landscapes, while the minimum of the two indexes show the opposite trend but urban area; 2) The mean values of contagion index in the urban and farmland landscapes are bigger than the values of the hilly and mountainous landscapes. Otherwise, the mean value of evenness index is showing opposite characteristics from the contagion index; 3) The relationship of the contagion index and the evenness index is significantly negative (<em>R</em>² > 0.9) in the four different landscapes. However above the radius of 100m in urban landscape, the correlation of these two indexes in non-significantly negative (<em>R</em>² < 0.9). 4) The <em>β </em>values of the curve estimate show increasing trend from the radius of 100m to 1500m in the four different landscapes. When the moving window radius increases gradually,there are large numbers of various patches in the landscapes bringing about the whole change of landscape composition and configuration, and this would have an effect on the biodiversity, ecosystem stability and ecological system service. At the landscape level, the more complex landscape composition and configuration, the higher level of landscape heterogeneity. That means the numbers and the types of patches are various, and these patches are grouped in different types. The heterogeneity of hilly and mountains are higher than urban area and farmland, it proves that the human disturbance factors play an important role on the formation of landscape heterogeneity. Because of the human activities make the single type of land use, which reduces the landscape heterogeneity. As above said landscape heterogeneity has a very strong dependence on scales, so analyzing the landscape heterogeneity on multi-scale is very meaningful. We wish our study results can provide theoretical basis for a sustainable landscape management of agro-landscape in future.

Quantifying connectivity using graph based connectivity response curves in complex landscapes under simulated forest management scenarios

The maintenance of habitat connectivity is promoted as a method of biodiversity conservation in forest management. Graph based metrics have demonstrated efficacy at deriving landscape scale connectivity metrics from habitat maps. The response of a graph-based connectivity metric to changes in the size of gaps considered to fragment habitat is proposed as a method of quantifying the impacts of changes in landscape composition on connectivity across a range of spatial scales. The parameters that describe this relationship are proposed as indices to quantify changes in the amount, fragmentation and spatial dispersion of habitat in a landscape. Systematic manipulations of landscape structure demonstrated response curve sensitivity to the impacts of forestry that are predicted by the literature to affect habitat connectivity. The response to controlled manipulations of landscape structure was used to guide an examination of the efficacy of distributing habitat reserves as corridors to mitigate the impacts of forestry on landscape connectivity. I conclude that the parameters that describe the relationship between spatial scale and the probability of connectivity index values can be used to compare the impacts of alternative forest management strategies on landscape connectivity, distributing conservation areas as corridors resulted in minimal benefits to landscape connectivity, and that the benefits of corridors were further reduced when natural disturbances were included in model simulations.

Landscape resistance to movement of the poison frog, Oophaga pumilio, in the lowlands of northeastern Costa Rica

AbstractConversion of forests to agricultural land or pastures is occurring at a rapid rate in many tropical regions. Amphibians may be particularly susceptible to changes in landscape composition and connectivity because of their physiological characteristics and complex life cycles. We experimentally assessed landscape resistance for the dart‐poison frog Oophaga pumilio associated with two prevalent land‐cover types, secondary forests and pastures, in the northeastern lowlands of Costa Rica. We measured recapture rates of individuals displaced into forests and into pastures, the effects of microclimate on the movement performance of individuals, and the influence of land‐cover type and displacement distance on orientation ability of O. pumilio. Results showed a significant interaction between displacement distance and land‐cover type indicating greater resistance to movement experienced by individuals displaced into pastures compared with frogs displaced into forests. Microclimatic conditions in pastures had a detrimental effect on the movement performance of O. pumilio and initial orientation was both distance and habitat dependent. Understanding the magnitude of resistance presented by different land‐uses to amphibian dispersal is important for the development of successful conservation strategies in human‐altered landscapes.

Scale-dependent drivers of ungulate patch use along a temporal and spatial gradient of snow depth

Anthropogenic changes in landscape composition or configuration have the potential to increase the abundance of generalist species, often resulting in cascading effects on other trophic levels and ecosystem function. The selection or utilization of individual patches of habitat, however, may vary in both time and space, as a result of patch and landscape attributes as well as dynamic abiotic factors (i.e., snowfall). We hypothesized that the use of high-quality habitat would be most strongly influenced by snow at local scales and by composition and the configuration of the landscape at greater spatial scales. To test this, we examined white-tailed deer ( Odocoileus virginianus (Zimmermann, 1780)) selection of eastern hemlock ( Tsuga canadensis (L.) Carrière) patches as winter habitat over a 3-year period. Patch-level attributes were poor predictors of patch use in areas with strong gradients in abiotic factors relevant to the energetics of movement or forage acquisition. Additionally, heterogeneity in the greater landscape (3000 m radius buffer) served to increase use, while homogeneity appeared to decrease use. Our results suggest that interactions between deer migratory behavior, interannual variation in winter severity, and landscape context might provide spatial and temporal refugia for hemlock regeneration; a better understanding of which could aide conservation and restoration.

Landscape moderation of biodiversity patterns and processes ‐ eight hypotheses

Understanding how landscape characteristics affect biodiversity patterns and ecological processes at local and landscape scales is critical for mitigating effects of global environmental change. In this review, we use knowledge gained from human-modified landscapes to suggest eight hypotheses, which we hope will encourage more systematic research on the role of landscape composition and configuration in determining the structure of ecological communities, ecosystem functioning and services. We organize the eight hypotheses under four overarching themes. Section A: 'landscape moderation of biodiversity patterns' includes (1) the landscape species pool hypothesis-the size of the landscape-wide species pool moderates local (alpha) biodiversity, and (2) the dominance of beta diversity hypothesis-landscape-moderated dissimilarity of local communities determines landscape-wide biodiversity and overrides negative local effects of habitat fragmentation on biodiversity. Section B: 'landscape moderation of population dynamics' includes (3) the cross-habitat spillover hypothesis-landscape-moderated spillover of energy, resources and organisms across habitats, including between managed and natural ecosystems, influences landscape-wide community structure and associated processes and (4) the landscape-moderated concentration and dilution hypothesis-spatial and temporal changes in landscape composition can cause transient concentration or dilution of populations with functional consequences. Section C: 'landscape moderation of functional trait selection' includes (5) the landscape-moderated functional trait selection hypothesis-landscape moderation of species trait selection shapes the functional role and trajectory of community assembly, and (6) the landscape-moderated insurance hypothesis-landscape complexity provides spatial and temporal insurance, i.e. high resilience and stability of ecological processes in changing environments. Section D: 'landscape constraints on conservation management' includes (7) the intermediate landscape-complexity hypothesis-landscape-moderated effectiveness of local conservation management is highest in structurally simple, rather than in cleared (i.e. extremely simplified) or in complex landscapes, and (8) the landscape-moderated biodiversity versus ecosystem service management hypothesis-landscape-moderated biodiversity conservation to optimize functional diversity and related ecosystem services will not protect endangered species. Shifting our research focus from local to landscape-moderated effects on biodiversity will be critical to developing solutions for future biodiversity and ecosystem service management.

Comparison of regional stream and lake chemistry: Differences, similarities, and potential drivers

We compared lakes and streams in northern Wisconsin to ask how regional patterns of water chemistry differed, and how ecosystem size relates to water chemistry. By applying traditional statistical approaches in novel ways, we identified factors influencing regional chemistry of lakes and streams. Chemistry differed significantly among the two ecosystem types (p = 0.01), and two distinct variable groups were apparent. Almost two thirds of the variation in 16 constituents was associated with concentration gradients related to groundwater inputs (group 1, represented by Ca) and adjacent wetlands (group 2, represented by dissolved organic carbon [DOC]). Largest differences were observed in groundwater‐associated variables. Median Ca concentrations in lakes were an order of magnitude lower than in streams (lake = 1.43 mg L−1, stream = 12.45 mg L−1), and indicate that regional lake chemistry is strongly influenced by precipitation or short groundwater flow paths, whereas streams are more affected by groundwater with substantial mineral water contact. In contrast, variables reflecting wetland influence (e.g., DOC) did not differ between streams and lakes. Despite these differences, as lake and stream size increased, their biogeochemical attributes converged, likely reflecting increased diversity of flow paths to larger systems, greater biogeochemical processing, and changes in landscape composition. Our results have identified critical differences (groundwater inputs) and similarities (organic carbon dynamics) between lakes and streams and emphasize the importance of ecosystem size in interpreting these observations at the regional scale. Studies such as this will provide essential pieces of information for regional and global biogeochemical studies of freshwater ecosystems.

Effects of projected future urban land cover on nitrogen and phosphorus runoff to Chesapeake Bay

This paper examined the effects of simulated land cover/land use (LC/LU) change from 2000 to 2030 on nutrient loadings to the Chesapeake Bay. The SPAtially Referenced Regression On Watershed Attributes (SPARROW) model was used with anticipated watershed-wide LC/LU change from a growth forecast model that provides spatially explicit probabilities of conversion to impervious surface. The total nitrogen (TN) and total phosphorus (TP) loadings estimated to enter the Chesapeake Bay were reduced by 20% and 19%, respectively. In general, as development replaced other LC/LUs from 2000 to 2030, TN and TP runoff was significantly reduced by losses of non-point, non-urban source loadings, yields, and land-to-water delivery. The simulation results suggest future changes in landscape composition and configuration at catchment and riparian stream buffer width scales could lower TN and TP runoff to the estuary.