Forest-dominated Landscape Research Articles

How frequent is metapopulation structure among butterflies in grasslands? Occurrence patterns in a forest-dominated landscape in southern Sweden

We determined the proportion of butterfly species that occur as metapopulations with grasslands as the only habitat. We counted all butterflies in 19 semi-natural grassland patches in a forest-dominated landscape in southern Sweden over a 5-y period. Seven of the 44 butterfly species observed exhibited a metapopulation structure. The other species either use grassland mainly for adult feeding but not for breeding (8 species), breed both in grassland and in surrounding habitat types (19 species), or are grassland specialists but their colonization—extinction dynamics are probably not significant, since they were present in nearly all (> 80%) patches (10 species). Occupancy was generally higher in larger patches, and tended to increase with patch connectivity. Among grassland specialists and habitat generalists, the connectivity measure tended to explain more of the variation in occupancy if the shortest dispersal paths avoiding routes over water were considered rather than a measure based on the Euclidian distance between patches. This indicates that lakes, even when they are just a few hundred metres wide, can act as barriers to dispersal for butterflies. We conclude that for many butterflies that occur in semi- natural grasslands in forest-dominated landscapes, intervening habitats are important as breeding sites or as dispersal barriers.

A meta-analysis of bird and mammal response to short-rotation woody crops

Short-rotation woody cropping (SRWC) refers to silvicultural systems designed to produce woody biomass using short harvest cycles (1–15 years), intensive silvicultural techniques, high-yielding varieties, and often coppice regeneration. Recent emphasis on alternatives to fossil fuels has spurred interest in producing SRWC on privately owned and intensively managed forests of North America. We examined potential bird and small mammal response at the stand level to conversion of existing, intensively managed forests to SRWCs using meta-analysis of existing studies. We found 257 effect sizes for birds (243 effect sizes) and mammals (14 effect sizes) from 8 studies involving Populus spp. plantations. Diversity and abundance of bird guilds were lower on short-rotation plantations compared with reference woodlands, while abundance of individual bird species was more variable and not consistently higher or lower on SRWC plantations. Shrub-associated birds were more abundant on SRWC plantations, but forest-associated and cavity-nesting birds were less abundant. Effects on birds appeared to decrease with age of the SRWC plantation, but plantation age was also confounded with variation in the type of reference forest used for comparison. Both guilds and species of mammals were less abundant on SRWC plantations. These conclusions are tentative because none of these studies directly compared SRWC plantations to intensively managed forests. Plantations of SRWCs could contribute to overall landscape diversity in forest-dominated landscapes by providing shrubby habitat structure for nonforest species. However, extensive conversion of mature or intensively managed forests to SRWC would likely decrease overall diversity, especially if they replace habitat types of high conservation value.

Conserving butterflies in fragmented plantation forests: are edge and interior habitats equally important?

Edge effects are increasing in forest-dominated landscapes worldwide, due to increased fragmentation by other land uses. Understanding how species respond to edges is therefore critical to define adequate conservation measures. We compared the relative importance of interior and edge habitats for butterflies in a landscape composed of even-aged pine plantations interspersed with semi-natural habitats. Butterfly assemblages were surveyed simultaneously at the edge and the interior of 68 patches belonging to four main habitat types: herbaceous firebreaks, clearcuts and young pine stands, older pine stands, and deciduous woodlands. Butterfly species richness was higher at edges than in interior habitats, especially for pine stands. Assemblage composition differed significantly between edge and interior habitats, except for firebreaks. Of the 23 most abundant butterfly species, seven were significantly more abundant in one or all edge habitat types, five in interior habitats, and 11 species showed no edge-interior preference. Modelling the presence of individual species in edge habitats revealed the importance of habitat variables such as the abundance of nectar and host-plants, but also of the abundance of the same species in the adjacent interior habitat. Moreover, our results suggest that most species use several, different habitat types to find supplementary or complementary resources, including micro-climatic refuges to escape hot temperatures during summer. The use of adjacent edge and interior habitats by butterflies is probably a key process in such mosaic landscapes and underlines the importance of landscape heterogeneity for butterfly conservation.

An approach to GIS-based multiple criteria decision analysis that integrates exploration and evaluation phases: Case study in a forest-dominated landscape

The increasing importance and complexity of land and natural resource management are creating a need for ecosystem-based management (EBM). Multiple criteria decision analysis (MCDA) combined with geographic information systems (GIS) can integrate factors related to the triple bottom line of ecological, economic, and social perspectives required by EBM. However, GIS-based MCDA is limited in this role because (i) it rarely integrates or encourages an exploration phase in preparation for structured evaluation and (ii) inexperienced users may find MCDA methods and GIS software difficult to use. This paper presents a novel approach for (i) supporting an exploration phase to help structure a problem and (ii) integrating the exploration and evaluation phases in an easy-to-use software system. The approach was validated through a land-management case study in a forest-dominated landscape with a variety of stakeholders. Case-study participants used the approach to rate areas within a timber harvest plan based on their potential for conflict with conservation values. The case-study decision analysis determined that between 1.3% and 6.6% of the harvest plan area had a conservation rating of 0.30 or higher on a scale of 0–1. The system was made available to the forest industry and other stakeholders to support harvest plan adjustments, demonstrating how such tools can be used to improve and integrate our knowledge of forest ecology and management. Assessment of participant feedback reveals that an exploration phase is effective in helping understand a problem and prepare for multiple criteria evaluation (MCE).

Space and habitat use of moose in southwestern Sweden

Increasingly, wildlife managers and land managers are challenged to maintain the viability of large mammal populations. Although the moose (Alces alces) is an ecologically, economically, and culturally important ungulate species found throughout most of Sweden, little is known about its ecology throughout the southern part of the country. We collected baseline ecological data on spatial and habitat use patterns in urbanized southwestern Sweden by fitting 22 adult moose (13 F, nine M) with global positioning system (GPS) radio collars. Home range size of cows did not differ among seasons (P > 0.10); however, bulls had larger home ranges during fall than all other seasons (P < 0.010). Mean home range size of males during fall and spring was larger than females during any season (P < 0.010). We used a Euclidean distance-based approach to analyze multi-scale habitat selection by moose. Moose of both sexes and during all seasons selected boreal forest and mires when establishing a home range (P < 0.10). Moose had seasonal differences in habitat selection within their home range (P 0.001), and generally selected clear-cuts and early successional forests, mature coniferous forests, and glades, but avoided agricultural areas and open water. Habitat and space use characteristics of moose in our urbanizing study area were similar to characteristics reported for moose in forest-dominated landscapes of Fennoscandia.

Effects of land-use history and the contemporary landscape on non-native plant invasion at local and regional scales in the forest-dominated southern Appalachians

Determining what factors explain the distribution of non-native invasive plants that can spread in forest-dominated landscapes could advance understanding of the invasion process and identify forest areas most susceptible to invasion. We conducted roadside surveys to determine the presence and abundance of 15 non-native plant species known to invade forests in western North Carolina, USA. Generalized linear models were used to examine how contemporary and historic land use, landscape context, and topography influenced presence and abundance of the species at local and regional scales. The most commonly encountered species were Microstegium vimineum, Rosa multiflora, Lonicera japonica, Celastrus orbiculatus, Ligustrum sinense, and Dioscorea oppositifolia. At the regional scale, distance to city center was the most important explanatory variable, with species more likely present and more abundant in watersheds closer to Asheville, NC. Many focal species were also more common in watersheds at lower elevation and with less forest cover. At the local scale, elevation was important for explaining the species’ presence, but forest cover and land-use history were more important for explaining their abundance. In general, species were more common in plots with less forest cover and more area reforested since the 1940s. Our results underscore the importance of considering both the contemporary landscape and historic land use to understand plant invasion in forest-dominated landscapes.

Correlation between lumbar BMD percentage change and ten-year probability of major osteoporotic fracture by FRAX and total number of previous fracture in postmenopausal osteoporotic women treated with PTH 1-84

Forest fragmentation is a major conservation issue, which includes interdependent components of forest loss and changes in their spatial patterns. Over the years, the Himalayan forests have experienced major changes, but data and documentation on patterns and causes of forest fragmentation are limited. In this study, we analyzed temporal changes (1990–2014) of forest loss and fragmentation using Landsat imageries in the Kumaon division of Uttarakhand state, India. To assess mechanisms causing forest fragmentation, we investigated changes in following quantitative parameters describing forest fragmentation: (i) forest area density (Pf), (ii) overall forest connectivity (Pff), (iii) anthropogenic fragmentation (Pfa), and (iv) natural fragmentation (Pfn). We found that this region is undergoing intensive forest fragmentation, shifting from forest-dominated landscapes to fragmented forests intermixed with agricultural lands and urban settlements. Overall, intact forest patches decreased between 1990 and 2009 (1442 km2), followed by a small gain from 2009 to 2014 (260 km2). In lower altitudes, anthropogenic activities caused fragmentation; while in higher altitudes, fragmentation can be attributed to natural causes. All districts within the region show a decreasing trend of forest cover area, with the highest rate of forest cover loss for the low-lying district of Udham Singh Nagar and the lowest rate for the high-lying district of Bageshwar. This trend can be associated with increasing population density in low-lying districts than high-lying districts. Our results emphasize on delineating spatial trends of forest loss and fragmentation to support the identification of conservation sites. The findings can further help in developing forest policies for maintaining local livelihood options in the Himalayan region.

A method for using Landsat time series for monitoring young plantations in boreal forests

A time series of Landsat Enhanced Thematic Mapper Plus (ETM+) imagery was used to investigate its potential contribution to characterization of young forest plantations in northern Sweden (latitude 65˚ N, longitude 16˚ E). The time series image data were first bandwise relatively normalized, using image statistics from forest areas. It was shown that the difference in reflectance development between different types of forest plantations could be characterized by fitting a linear regression model through the bandwise spectral mean values for each stand, starting 5 years after the final felling. The coefficients of this regression model can be used to improve statistically based characterizations of young forest, compared to using data from the most recent image only. This result is useful for screening stands that might be in need of precommercial thinning (PCT), as well as for improving forecasts of expected forest development for whole forest-dominated landscapes consisting of several estates.

Ancient Land Use and Management of Ebey's Prairie, Whidbey Island, Washington

Anthropogenic prairies or meadows along the Northwest Coast of North America are herbaceous lowland openings in a forest-dominated landscape that were historically maintained by indigenous people through intentional burning and other management techniques. These anthropogenic ecosystems were once relatively common in the Northwest, but today are threatened because of the cessation of traditional resource management practices often coupled with widespread development and fire suppression. In this study, we explore the long-term history of Ebey's Prairie, an anthropogenic prairie on Whidbey Island, WA. We use analyses of soils, cultural features, archaeobotanical remains, and artifacts to demonstrate that people have been using the Ebey's Prairie locale for a variety of activities over a broad time scale (about 10,000 to 250 years B.P.). Within at least the last 2,300 years people began setting fires to create and maintain a “prairie” landscape. From that time onward, people used this landscape to harvest a range of open ecosystem resources. Understanding the long-term cultural and natural history of Ebey's and other prairies is a fundamental first step to managing these ecosystems for the future.

Landscape Effects on Ecosystems: Birds as Active Vectors of Nutrient Transport to Fragmented Urban Forests Versus Forest-Dominated Landscapes

In urban landscapes, nearby birds contribute to allochthonous nutrient flow from residential areas to fragmented forests by consuming food in residential areas and depositing feces in forests. To estimate allochthonous nutrient flow qualitatively, the stable nitrogen (δ15N) and carbon (δ13C) isotope approach is useful. However, the quantitative allochthonous flow rate cannot be estimated by the stable-isotope approach. To quantify allochthonous input, we compare two different landscapes. We assume that the input rate in deep forests in the forest-dominated landscape is the basic autochthonous flow that is common to various forests, and estimate the allochthonous nutrient input by subtracting the autochthonous flow from the total input in urban forests. The observed nutrient-input rate in the forest-dominated landscape as the autochthonous flow is 0.0298 kg P ha−1 y−1 and 0.319 kg N ha−1 y−1. Using these values, the allochthonous P input (kg P ha−1 y−1) is estimated at 0.0307 in urban fragmented forests and 2.31 in forests with crow roosts, whereas N input (kg N ha−1 y−1) is 0.397 in urban fragmented forests and 23.2 in forests with crow roosts. Our estimation shows that, in urban forests with roosts, birds contribute 2.7 times the amount of allochthonous P contributed via other pathways, and in urban forests without roosts they contribute 0.035 times the amount; and in addition, birds contribute 0.66 times the amount of allochthonous N input via other pathways in urban forests with crow roosts and 0.011 times the amount in urban forests without roosts. We also measure stable nitrogen and carbon isotope ratios, %N, %P, and %C to estimate the diet of birds. High δ15N and δ13C values in crow roosts indicate that they eat foods such as livestock meat, C4 maize, or fish. High avian biomass is the major reason for the large nutrient input in urban landscapes, especially in urban forests with crow roosts.

Distribution pattern of an expanding Osprey (Pandion haliaetus) population in a changing environment

We studied the nest site selection and distribution pattern at landscape level of the German Osprey population, and demonstrated how to test the predictions of the ideal free distribution theory and its derivatives on such an expanding population. Information about the location and breeding success of each Osprey nest site between 1995 and 2005 was collected through a long-term monitoring programme. Data of land cover types were acquired from the administrations of each federal state and the CORINE Land Cover database. The results showed that Ospreys preferred landscapes with more water bodies and forests. Such sites were also occupied earlier and had higher local population density. However, in the study period of 11 years, there was a gradual shift from forest-dominated landscapes to agricultural land-dominated landscapes. The breeding success increased over time, with no difference in the breeding success between pairs nesting on trees and poles, whereas there was higher breeding success at nest sites surrounded by more agricultural land and less forest. The more efficient foraging in eutrophic lakes in agricultural landscapes was the most likely cause for the higher breeding success. The distribution pattern of the Ospreys did not match the resource allocation, which deviated from the models tested. We suggested that the proximate cues used for nest site selection mismatched site quality due to anthropogenic environmental changes.

Importance of semi-natural habitats for the conservation of butterfly communities in landscapes dominated by pine plantations

While the area of plantation forests continues to increase worldwide, their contribution to the conservation of biodiversity is still controversial. There is a particular concern on the central role played by natural habitat remnants embedded within the plantation matrix in conserving species-rich insect communities. We surveyed butterflies in maritime pine plantation landscapes in south-western France in 83 plots belonging to seven habitat types (five successional stages of pine stands, native deciduous woodlands and herbaceous firebreaks). The effect of plot, habitat and landscape attributes on butterfly species richness, community composition and individual species were analysed with a General Linear Model (GLM), partial Canonical Correspondence Analysis (CCA) and the IndVal method. The most important factors determining butterfly diversity and community composition were the presence of semi-natural habitats (deciduous woodlands and firebreaks) at the landscape scale and the composition of understorey vegetation at the plot scale. Pure effects of plot variables explained the largest part of community variation (12.8%), but landscape factors explained an additional, independent part (6.7%). Firebreaks were characterized by a higher species richness and both firebreaks and deciduous woodlands harboured species not or rarely found in pine stands. Despite the forest-dominated landscape, typical forest butterflies were rare and mainly found in the deciduous woodlands. Threatened species, such as Coenonympha oedippus and Euphydryas aurinia, were found in pine stands and in firebreaks, but were more abundant in the latter. In the studied plantation forest, the conservation of butterflies depends mainly on the preservation of semi-natural habitats, an adequate understorey management and the maintenance of soil moisture levels.

Pollen-recorded climate changes between 13.0 and 7.0 14C ka BP in southern Ningxia, China

A pollen record from Haiyuan section in the southern part of Ningxia revealed a detailed history of vegetation variation and associated climate changes during the period from ∼13.0 to ∼7.0 14C ka BP. A steppe landscape under a moderately dry (and probably cool) condition (∼12.7–∼12.1 14C ka BP) was replaced by a coniferous forest dominating the landscape under a generally wet climate from ∼12.1 to ∼11.0 14C ka BP. This generally wet period, corresponding to the European Bolling/Allerod period, can be divided into three stages: a cool and wet stage between ∼12.1 and ∼11.4 14C ka BP, a mild and relatively dry stage between ∼11.4 and ∼11.2 14C ka BP, and a mild and wet stage between ∼11.2 and ∼11.0 14C ka BP. The coniferous forest-dominated landscape was then deteriorated into steppe landscape (∼11.0–∼10.6 14C ka BP) and further into a desert steppe landscape from ∼10.6 to ∼9.8 14C ka BP, being correspondent to the European Younger Dryas period. After a brief episode of a cool and wet climate (∼9.8–∼9.6 14C ka BP), a relatively mild and dry condition prevailed during the early Holocene (∼9.6–∼7.6 14C ka BP) and then a warm and humid climate started the mid-Holocene (∼7.6–∼7.2 14C ka BP).

Local, Short-term Effects of Forest Harvesting on Breeding Waterfowl and Common Loon in Forest-Dominated Landscapes of Quebec

Lemelin, L. V., L. Imbeau, M. Darveau, and D. Bordage 2007. Local, short-term effects of forest harvesting on breeding waterfowl and Common Loon in forest-dominated landscapes of Quebec. Avian Conservation and Ecology - Écologie et conservation des oiseaux 2(2): 10.http://dx.doi.org/10.5751/ACE-00191-020210

Spatial simulation modelling of land use/land cover change scenarios in northeastern Thailand: a cellular automata approach

The cultivation of upland field crops, primarily cassava and sugar cane, in Nang Rong district, northeast Thailand, beginning in the mid- to late 1960s, has helped transform a once forest-dominated landscape to one dominated by agriculture. Today, paddy rice is cultivated throughout the lowlands, field crops and a fragmented forest matrix comprise the uplands, and fruit trees, rubber plantations, and vegetable gardens are among the crops dispersed around nuclear villages. Distributed along a topographic terrace system, upland and lowland crops are cultivated relative to environmental and economic opportunities and geographic access, although crops grown in marginal settings may not be sustainable. Relying upon a remote sensing image time-series, a longitudinal social survey, and GIS coverages, a cellular automata (CA) model is described that is used to characterize land use and land cover (LULC) change patterns through specified initial conditions, neighbourhood associations, and transition or growth rules. Results of four scenarios or experiments are described that perturb the base LULC change model of cassava, forest, and rice by imposing production quotas in the cultivation of cassava. Derived for the period 1972–2001, CA model results for the scenarios are compared to a time-series of Landsat satellite classifications of LULC using images of simulation runs and plots that describe trends in the composition and spatial organisation of cassava, forest, and rice for each scenario. Results are interpreted within a population-environment context in which people, place, and environment are integrated in complex ways. The demise of forest at the expense of expanded lowland paddy rice and upland field crops is a central story of the region. Quotas on the production of cassava alter the trajectories of forest change and result in more consolidated forest stands over the period of the simulations. Cassava consolidation and in-filling in the extensive uplands of the southwest portion of Nang Rong district is a persistent outcome of the simulations for the various scenarios tested.

The importance of spatial autocorrelation, extent and resolution in predicting forest bird occurrence

Concerns about declines in forest biodiversity underscore the need for accurate estimates of the distribution and abundance of organisms at large scales and at resolutions that are fine enough to be appropriate for management. This paper addresses three major objectives: (i) to determine whether the resolution of typical air photo-derived forest inventory is sufficient for the accurate prediction of site occupancy by forest birds. We compared prediction success of habitat models using air photo variables to models with variables derived from finer resolution, ground-sampled vegetation plots. (ii) To test whether incorporating spatial autocorrelation into habitat models via autologistic regression increases prediction success. (iii) To determine whether landscape structure is an important factor in predicting bird distribution in forest-dominated landscapes. Models were tested locally (Greater Fundy Ecosystem [GFE]) using cross-validation, and regionally using an independent data set from an area located ca. 250 km to the northwest (Riley Brook [RB]). We found significant positive spatial autocorrelation in the residuals of at least one habitat model for 76% (16/21) of species examined. In these cases, the logistic regression assumption of spatially independent errors was violated. Logistic models that ignored spatial autocorrelation tended to overestimate habitat effects. Though overall prediction success was higher for autologistic models than logistic models in the GFE, the difference was only significantly improved for one species. Further, the inclusion of spatial covariates did little to improve model performance in the geographically discrete study area. For 62% (13/21) of species examined, landscape variables were significant predictors of forest bird occurrence even after statistically controlling for stand-level variability. However, broad spatial extents explained less variation than local factors. In the GFE, 76% (16/21) of air photo and 81% (17/21) of ground plot models were accurate enough to be of practical utility (AUC > 0.7). When applied to RB, both model types performed effectively for 55% (11/20) of the species examined. We did not detect an overall difference in prediction success between air photo and ground plot models in either study area. We conclude that air photo data are as effective as fine resolution vegetation data for predicting site occupancy for the majority of species in this study. These models will be of use to forest managers who are interested in mapping species distributions under various timber harvest scenarios, and to protected areas planners attempting to optimize reserve function.

Effects of landscape characteristics on amphibian distribution in a forest-dominated landscape

We investigated the influence of landscape and wetland characteristics on pond-breeding amphibian assemblages in south-central New Hampshire, a relatively low populated and heavily forested region of the northeastern United States. This allowed us to better understand landscape influences in less disturbed areas, and to determine critical landscape disturbance thresholds, above which amphibians are negatively impacted. We sampled 61 wetlands for larval amphibians in 1998 and 1999 to examine the influence of forest cover and road density (at seven buffer distances between 100 and 2000 m) and wetland characteristics on larval amphibian assemblages. Assemblages were influenced primarily by forest cover and wetland hydroperiod. Species richness was most strongly influenced by the proportion of forest cover within 1000 m of the wetland. Several species were also influenced by forest cover, but were differentially influenced by buffer widths. Our study suggests that, at least in the northeast US, wetlands with <40% forest cover within a 1000 m radius may have depauperate larval amphibian assemblages, and forest cover above 60% within a 1000 m radius is likely to ensure species rich and abundant larval amphibian assemblages. Given the above, current federal and state regulations that focus amphibian protection efforts on narrow terrestrial buffers surrounding wetlands are likely to be inadequate.

Local values for harvested forest plants in Madre de Dios, Peru: Towards a more contextualised interpretation of quantitative ethnobotanical data

This study builds on earlier quantitative ethnobotanical studies to develop an approach which represents local values for useful forest species, in order to explore factors affecting those values. The method, based on respondents' ranking of taxa, compares favourably with more time-consuming quantitative ethnobotanical techniques, and allows results to be differentiated according to social factors (gender and ethnic origin), and ecological and socio-economic context. We worked with 126 respondents in five indigenous and five immigrant communities within a forest-dominated landscape in the Peruvian Amazonia. There was wide variability among responses, indicating a complex of factors affecting value. The most valued family is Arecaceae, followed by Fabaceae and Moraceae. Overall, fruit and non- commercialised construction materials predominate but women tend to value fruit and other non-timber species more highly than timber, while the converse is shown by men. Indigenous respondents tend to value more the species used for fruit, domestic construction and other NTFPs, while immigrants tend to favour commercialised timber species. Across all communities, values are influenced by both markets and the availability of the taxa; as the favourite species become scarce, others replace them in perceived importance. As markets become more accessible, over-exploitation of the most valuable species and livelihood diversification contribute to a decrease in perceived value of the forest.

LANDSCAPE-LEVEL PATTERNS OF AVIAN DIVERSITY IN THE OREGON COAST RANGE

We used a comparative mensurative landscape-level experiment to quantify the relative importance of mature forest area and fragmentation and differences among watersheds in influencing avian community diversity in the Oregon Coast Range, USA. Our study design included three large hydrological basins, two levels of fragmentation, and six levels of mature forest area. We recorded 82 species of birds in a total of 1046 plots in 30 landscapes. Our four response variables were species richness, species density, species evenness, and total bird density. We used a combination of factorial ANOVA and partial canonical variates analysis to quantify the relative importance of differences in mature forest area, fragmentation, and basin in influencing each response variable and community diversity overall. Bird community diversity was influenced by both the extent and fragmentation of mature forest at the landscape level. Species richness and density responded more strongly to mature forest area than to fragmentation and were significantly lower in landscapes that were completely dominated by mature forest than in landscapes with a mixture of seral stages. This reflected a selective loss of a number of early-seral species when mature forest completely blanketed the landscape. Species evenness was more strongly related to fragmentation than to area of mature forest at the landscape level. In fragmented landscapes, the most dominant species decreased in abundance, whereas moderately abundant species increased in relative abundance. This resulted in bird communities that were more even in fragmented landscapes. Unlike several other studies, we did not find that the relative strength of fragmentation effects increased as habitat area decreased. Total bird density, in contrast, was not related to either mature forest area or fragmentation, but it varied significantly among basins. In summary, although both area and fragmentation of mature forest at the landscape level were strongly related to bird community diversity, they had qualitatively different effects. These results must be interpreted within the scope of this study, which took place in a forest-dominated landscape. Our results provide an interesting view of the factors that are related to bird diversity in a spatially complex seral mosaic but may not reflect the patterns that would exist in a high-contrast forest–nonforest landscape. Corresponding Editor: N. C. Kenkel.

Landscape effects on temporal and spatial properties of vole population fluctuations

Populations of northern small rodents have previously been observed to fluctuate in spatial synchrony over distances ranging from tens to hundreds of kilometers between sites. It has been suggested that this phenomenon is caused by common environmental perturbations, mobile predators or dispersal movements. However, very little focus has been given to how the physical properties of the geographic area over which synchrony occurs, such as landscape composition and climate, affect spatial population dynamics. This study reports on the spatial and temporal properties of vole population fluctuations in two areas of western Finland: one composed of large interconnected areas of agricultural farmland interspersed by forests and the other highly dominated by forest areas, containing more isolated patches of agricultural land. Furthermore, the more agricultural area exhibits somewhat milder winters with less snow than the forested area. We found the amplitude of vole cycles to be essentially the same in the two areas, suggesting that the relative amount of predation on small rodents by generalist versus specialist predators is similar in both areas. No seasonal differences in the timing of synchronization were observable for Microtus voles, whereas bank vole populations in field habitats appeared to become synchronized primarily during winter. Microtus populations in field habitats exhibited smaller spatial variation and a higher degree of synchrony in the more continuous agricultural landscape than in the forest-dominated landscape. We suggest that this inter-areal difference is due to differences in the degree of inter-patch connectivity, with predators and dispersal acting as the primary synchronizing agents. Bank vole populations in field habitats were more synchronized within the forest-dominated landscape, most likely reflecting the suitability of the inter-patch matrix and the possibility of dispersal. Our study clearly indicates that landscape composition needs to be taken into account when describing the spatial properties of small rodent population dynamics.