Mean Patch Size Research Articles

Quantifying Relationships Between Bird And Butterfly Community Shifts And Environmental Change

Quantifying the manner in which ecological communities respond during a time of decreasing precipitation is a first step in understanding how they will respond to longer-term climate change. Here we coupled analysis of interannual variability in remotely sensed data with analyses of bird and butterfly community changes in montane meadow communities of the Greater Yellowstone Ecosystem. Landsat satellite imagery was used to classify these meadows into six types along a hydrological gradient. The northern portion of the ecosystem, or Gallatin region, has smaller mean patch sizes separated by ridges of mountains, whereas the southern portion of the ecosystem, or Teton region, has much larger patches within the Jackson Hole valley. Both support a similar suite of butterfly and bird species. The Gallatin region showed more overall among-year variation in the normalized difference vegetation index (NDVI) when meadow types were pooled within regions, perhaps because the patch sizes are smaller on average. Bird and butterfly communities showed significant relationships relative to meadow type and NDVI. We identified several key species that are tightly associated with specific meadow types along the hydrological gradient. Comparing taxonomic groups, fewer birds showed specific habitat affinities than butterflies, perhaps because birds are responding to differences in habitat structure among meadow types and using the landscape at a coarser scale than the butterflies. Comparing regions, the Teton region showed higher predictability of community assemblages as compared to the Gallatin region. The Gallatin region exhibited more significant temporal trends with respect to butterflies. Butterfly communities in wet meadows showed a distinctive shift along the hydrological gradient during a drought period (1997-2000). These results imply that the larger Teton meadows will show more predictable (i.e., static) species-habitat associations over the long term, but that the smaller Gallatin meadows may be an area that will exhibit the effects of global climate change faster.

Logging-induced change (1930-2002) of a preindustrial landscape at the northern range limit of northern hardwoods, eastern Canada

Logging-induced changes from preindustrial (1930) to current conditions (2002) were studied in a landscape covering 13 550 ha in eastern Quebec. Age and types of forest cover were compared between 1930 and 2002 forest maps. In addition, we compared relative species abundance between living stems and coarse woody debris to study these changes at the stand scale. More than 90% of the 1930 preindustrial landscape was composed of forest stands older than 100 years. A balsam fir (Abies balsamea (L.) Mill.) – white spruce (Picea glauca (Moench) Voss) dominated conifer cover (77% of the landscape area) formed the landscape matrix across the lowlands and was intermingled with mixed stands of sugar maple (Acer saccharum Marsh.) and conifers on the highlands. As a result of recurrent logging, stands less than 70 years old accounted for 93% of the 2002 landscape. From 1930 to 2002, 37% of the landscape was converted from coniferous to mixed forest, and 19% evolved towards a deciduous cover. The total number of cover patches doubled to 193, whereas mean patch size decreased twofold to 65 ha. Sugar maple, red maple (Acer rubrum L.), striped maple (Acer pennsylvanicum L.), and white birch (Betula papyrifera Marsh.) probably experienced a greater increase in abundance, whereas balsam fir, white spruce, and eastern white-cedar (Thuja occidentalis L.) experienced a more pronounced decrease. Because it does not consider preindustrial landscape patterns, the system of ecological land classification currently in use in this area suggests that potential late-successional cover types should be more similar to present-day than to preindustrial conditions.

Effects of changes in agricultural land-use on landscape structure and arable weed vegetation over the last 50 years

Agricultural dynamics and associated changes in the structure of habitat patches affect species composition and distribution in the landscape. Land-use, landscape changes and vegetation changes of weeds were analysed in a 4 km 2 area in Central Germany (Saxony-Anhalt) from 1953 to 2000. This period includes the collectivisation (1952–1968), the agricultural industrialisation (1969–1989) and the privatisation of agricultural land following the political changes in East Germany in 1990. For the analyses, historic and current aerial photographs and vegetation data were used. Landscape indices and the average amount of mineral fertilizers were used as indicators for landscape structure and land-use intensity. Intensification of agriculture and the collectivisation in East Germany in the fifties and sixties led to a decline of the spatial heterogeneity of the landscape matrix (arable fields). The average number and cover of weed species, especially archaeophytes, decreased significantly since 1957. However, the total number of weed species increased. There was a remarkably high number of species with an average cover below 0.05%, called “chance” species in 2000. Out of 17 tested landscape indices only mean patch size and mean patch fractal dimension were significantly correlated with the average number of weed species. The average amount of the mineral fertilizer potash used as land-use intensity indicator was significantly negatively correlated with the total number of weed species. However, there was an increase in the number of farms after 1990 without changes in landscape structure and arable weed vegetation. The results suggest that structural variability of the landscape and habitat quality are the principal correlates of plant species diversity.

Seismic Cutlines, Changing Landscape Metrics and Grizzly Bear Landscape use in Alberta

Besides providing habitat to the grizzly bear (Ursus arctos) and other wildlife, the Rocky Mountain foothills of Alberta, Canada hosts considerable mining, seismic oil and gas exploration and production, and forest harvesting activities. Worldwide, such human activities influence the configuration and composition of the landscape. We assessed seismic cutline effects on landscape structure and grizzly bear use during early summer of 1999 and 2000. We studied five female and two male bears, which were GPS-collared in the spring following den emergence. The area available to this population was stratified into 49 km2 hexagon-shaped sub-landscapes. The scale of this stratification was determined by patterns of bear movement. Fourteen compositional and configurational landscape metrics were calculated within each landscape unit, and bear use points were pooled or ‘binned’ within each unit. Landscape use was related to landscape metrics using a Generalized Linear Model (GLM). We found that seismic cutline proportion did not explain landscape use by grizzly bears; however secondary effects of cutlines on landscape structure did. Declining use was mainly associated with increasing proportions of closed forest, and increasing variation of inter-patch distances, while use was mainly increasing with increasing mean patch size. An earlier investigation had demonstrated that adding seismic cutlines to grizzly bear habitat caused increases in the variation of inter-patch distances. Since the landscape structure of this grizzly bear population will continue to change as a function of increased levels of resource extraction activities in the near future, it is crucial to further study the detailed meaning of landscape structure at the large and small scale for effective conservation efforts.

ESTIMATION OF MANATEE (TRICHECHUS MANATUS LATIROSTRIS) PLACES AND MOVEMENT CORRIDORS USING TELEMETRY DATA

Effective stewardship of Florida's coast requires, in part, detailed characterizations of ecological components of the marine system. Characterization of one component, manatees (Trichechus manatus latirostris), involves mapping its distribution and abundance and identifying features of the landscape that are intimately associated with its life history. In this study, we developed a raster‐based spatial model that transformed radio‐telemetry point data to surfaces illustrating the areas manatees visited frequently for relatively long periods, called “places,” and areas visited frequently for short periods, called “movement corridors.” This work involved (1) simulating manatee movement paths between sequential telemetry points using a cost surface based on manatee bathymetric preferences that were derived from empirical associations between telemetry locations and water depth, (2) distributing movement time to cells that were crossed by the simulated movement path, and (3) extracting cells from the movement‐path map that qualified as places and those that qualified as corridors. Movement characteristics of wild and rehabilitated animals were similar. Movement rates of males were significantly greater than those of either females with calves or females without calves. Mean number of visits per cell and mean time per visit for the three adult classes were not significantly different. Males had the smallest mean patch size for places, and females without calves had the largest but fewest places. Based on qualitative evaluations by field biologists, we concluded that the model performed well in estimating places. The locations of movement corridors were less certain, although reasonable, given that manatee spatial cognition was considered sufficient to permit directed movement between places.

Assessment of ASTER land cover and MODIS NDVI data at multiple scales for ecological characterization of an arid urban center

Study of the detailed structure and ecological functioning of urban and peri-urban systems is intensifying due to increasing concentration of the human population into urban centers. Much of this increase is expected to occur in semiarid to arid cites. Data from new high spatial, temporal, and spectral resolution satellite-based sensors promise to increase our understanding of global urban ecological and climatic processes and improve city and land planning capabilities. Two of these sensors, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and the Moderate Resolution Imaging Spectroradiometer (MODIS), provide an opportunity to compare urban spatial structure (distribution and configuration of discrete land cover/land use classes on the landscape) with contemporaneous measurements of surface biophysical composition at a variety of spatial and temporal scales. Such combined measurements are useful for modeling changes to urban climate, hydrology, and biogeochemical cycles caused by modification of the landscape. We compare gridded landscape metrics derived from expert system land cover classification of ASTER to corresponding MODIS NDVI data at scales of 250 m/pixel, 500 m/pixel, and 1 km/pixel in order to determine which of these scales is optimal for monitoring of urban biophysical processes and landscape structure change. Weak positive and negative correlations between NDVI and landscape structure were observed at all three spatial scales for the metrics Class Area, Mean Patch Size, Edge Density, and Interspersion/Juxtaposition Index.

Patterns and causes of deforestation in the Colombian Amazon

Ecosystem information on the Colombian Amazonia is poor in comparison with that on the Brazilian Amazon. We examined patterns of ecosystem diversity, deforestation and fragmentation and provided an estimate on their possible causes through a temporal and spatial analysis of biotic and abiotic data using remote sensing and geographical information systems in six pilot areas covering a total of 4,200,000 ha. Ecological, demographic and socio-economic data were analysed to establish the local conditions. We used a landscape ecology approach to calculate indicators of ecosystem diversity, cover and forest fragmentation such as number of patches, mean patch size, mean shape index and mean nearest neighbour distance. Patterns of deforestation did not run parallel to access roads; instead the typical pattern of unplanned colonization follows the only transportation network existing in many areas in the Colombian Amazonia: rivers. In addition, we have used indicators of human influence such as demographic pressure, quality of life and economic activity indicators. Results show that the extent and rate of change varies between areas depending on population density. Annual deforestation rates were 3.73 and 0.97% in the high population density growth areas of Alto Putumayo and Macarena respectively, and 0.31, 0.23, and 0.01% in the relatively unpopulated areas of indigenous population. These changes are related to land use history as well as to environmental and historical socio-economic factors such as oil extraction, deforestation, cattle ranching or illegal cropping. The current situation in the region suggests that tropical deforestation rates in the Colombian Amazon are substantially higher than those found in previous studies in the rest of the Amazon.

Changes in landscape spatial pattern in the highly developing state of Selangor, peninsular Malaysia

In Malaysia, rapid changes in land use invariably portrayed have a relationship with environmental degradation. However, this has always been stated without any quantitative measurement for understanding the relationship in order to describe implications for land use planning and management. To understand the relationship this study addresses landscape pattern and landscape type responses to changes in land use in the state of Selangor, Malaysia as a case study. Three land use maps representing the years of 1966, 1981 and 1995 were used in this study. These maps were divided into 100 grid squares with each grid square has 10 km × 10 km dimension. These grid squares were used as a sampling unit for land use and landscape pattern change analyses. Based on proportion of land use categories, the landscape type of each grid square was determined. Results show that between 1966 and 1981 only one land use category significantly changed ( p < 0.05) in its proportion compared to five land use categories between 1981 and 1995. This indicates that human land use intensity increased between 1981 and 1995. As response to the intensity of land use change, fragmentation (measured by number of patches and mean patch size metrics) and diversity (measured by relative patch richness metric) of the state's landscape increased from 1981 to 1995. Changes in land use also influenced the landscape types and its dynamic of change. Two categories of landscape types; human landscape (cropland, semi-natural and mixed landscapes) and natural landscape (forest and wetland landscapes) characterized the state landscape. Based on the number of grid squares human landscape increased over the period, whereas natural landscape decreased. Between 1966 and 1981, change from one landscape type to another was predominantly occurred in human landscape. Between 1981 and 1995, change was mainly occurred in the natural landscape. Developmental activities might have been less intense in the human landscape, but they had a much greater impact on the natural ecosystem. This study also revealed the potential of landscape type as a reference for land evaluation and complement to landscape metric as measurement for monitoring changes in a landscape. Finally, we conclude that it is important to understand the changes of land use intensification and its effects on landscape pattern as well as landscape types and their dynamic of change in order to describe the implications for land use planning and management.

Seagrass landscape-scale changes in response to disturbance created by the dynamics of barrier-islands: A case study from Ria Formosa (Southern Portugal)

This study documents long-term changes of a Zostera noltii landscape induced by a natural cyclic event in a coastal lagoon. The barrier-islands forming this system are very dynamic with drifting movements controlling ecological patterns and processes occurring in this area. Changes in the areal extent of the Z. noltii meadows were assessed using historical aerial photographs from 1940, 1980, 1989, 1996 and 1998. Landscape indices such as total patch area (TA), mean patch size (MPS), number of patches (NP), mean shape coefficient of variation (CV) and landscape fractal dimension (D) were calculated for each year and related to an index of disturbance intensity. The spatial distribution of the Z. noltii meadows varied greatly during the studied period and changes observed were related to the disturbance created by the barrier-islands' spatial dynamics. After an artificial inlet relocation the Z. noltii area, number of patches, patch mean size and coefficient of variation decreased. The fractal dimension of the Z. noltii landscape increased by 50% showing that besides a decrease in total area, number of patches, and patch mean area, patch fragmentation was an important consequence of this anthropogenic disturbance. Seagrass natural distribution patterns changed in response to natural and human-induced activities. This study emphasizes the importance of the landscape approach and the historical perspective when studying seagrass changes and the importance of taking into consideration long-term changes in seagrass landscapes to avoid confusion between man-induced effects with natural cyclic events.

Using heterogeneity and representation of ecosite criteria to select forest reserves in an intensively managed industrial forest

The 189,000 ha privately owned, industrial Black Brook District in New Brunswick, Canada, contains 27 forest reserve areas, totaling 9500 ha (5%), with a primary management strategy of conservation protection. We conducted a gap analysis of the current reserve network, to evaluate representation by ecosite, and tested two approaches to identify potential additional reserves to increase to target areas of 6%, 7%, 10% and 15%: (1) selecting areas with maximum diversity of forest species composition, soil types, and elevation classes (‘heterogeneity method’, to incorporate the greatest amount of forest features in the smallest area); and (2) selecting areas to cover a total of 10% of the landbase, with 10% coverage of each ecosite area, if possible (‘representation method’). With a 10% target, the heterogeneity and representation methods resulted in 29 and 42 reserves, ranging from 490–2000 to 50–1500 ha, respectively. The heterogeneity method resulted in 13 fewer reserves, 10% more core area, 30% larger mean patch size, and 30% less edge. Representation of ecosites ranged from 0.9% to 23.3% in the current reserve network, 6.7–26.5% for the heterogeneity method, and 8.0–26.4% for the representation method. In simulations of management scenarios with 39–64% plantations and 10% unharvested reserves, projected softwood harvest was similar with both methods, at 2.3–2.5 million m 3 per 5-year period, while hardwood harvest was 0.02–0.09 million m 3 higher, at 0.79–0.82 million m 3 per 5-year period, with the representation than the heterogeneity method. Projected areas of old hardwood, softwood, and mixedwood habitats, defined based upon stand structure characteristics, were similar between the two methods, with up to 1000 ha more with the representation method in some projection periods. We conclude that the heterogeneity method was more effective in that it selected fewer reserves, with larger areas, more core area, and less edge.

Landscape-level movements of North American elk (Cervus elaphus): effects of habitat patch structure and topography

We examined movements of North American elk (Cervus elaphus) in northeastern Oregon, USA. Movement vectors at 449 locations over a 7762 ha area were calculated based on 16,724 sequential observations of 94 female elk-year combinations during spring (15 April–14 May) 1993, 1995, 1996. We calculated movement vectors at the start of morning and evening feeding bouts (0500, 1900 h) and during periods of least activity (0100, 1500 h). Here, we measured characteristics of habitat patches (habitat type, mean patch size, coefficient of variation in patch size, edge density, mean shape index, and mean nearest neighbor) at two levels of habitat grain (eight habitat types, two habitat types) and at three spatial scales (250, 500, and 1000 m) around each movement vector. We also measured topographic features around each vector including distance to nearest stream, direction of drainage, elevation, slope, and convexity (a measure of ridge top vs. valley bottom land form). We used mixed models adjusted for positive spatial correlation among vectors to examine the relationship between vector length, or speed of movement, and habitat patch characteristics, and between vector direction and topographic features. Speed of movements by elk were not related to characteristics of habitat patches that we measured. The direction of movement, however, was dependent on topography. Elk were more likely to move parallel to major drainages than perpendicular to them. Furthermore, elk were less likely to move perpendicular to drainages when close to the nearest stream, in valley bottoms vs. ridge tops, and on steep slopes. The dendritic nature of movements by elk with respect to topography may help elucidate ecosystem processes such as nutrient flows, nutrient cycling, and successional trajectories of plant communities.

Scales of movement by elk (Cervus elaphus) in response to heterogeneity in forage resources and predation risk

Animals may respond to spatial and temporal heterogeneity by altering their movement patterns. The time an animal spends in an area of a given size is termed ȁ8first-passage timeȁ9 and can be used to identify the scales at which different movement processes occur. Using first-passage time and 2-h observations, we identified nested spatial scales representing three movement behaviours for elk (Cervus elaphus) – inactive/resting (moves < 50 m), active/foraging (x = 276.7 m, SD = 56.6), and active/relocating (x = 1628.3 m, SD = 436.6). Our ability to identify inactive behaviour was limited by GPS accuracy. The scale separating relocating and foraging behaviour ranged 550–1650 m across individuals and varied quadratically with the mean patch size of cutover forest in an animal’s home range. We classified path segments into the 3 movement behaviours and related behaviours to local environmental conditions. Elk were likely to be inactive in areas having a low predicted use by wolves (Canis lupus), farther than 50 m from anthropogenic linear clearings, and where microclimatic conditions were cool (high shrub cover and north to east-facing slopes). In contrast, elk were most likely to forage in areas having intermediate levels of herbaceous biomass and low movement costs. Elk were most likely to be relocating when in areas of high wolf use, when close to linear clearings, and in energetically costly situations such as moving upslope. We discuss how elk use of potential foraging habitats may be restricted in this landscape by risks imposed by predators, humans, or both.

The Sensitivity of SIR-C Backscatter to Fire-Related Forest Spatial Patterns

This research investigates the use of Shuttle Imaging Radar (SIR-C) data to analyze spatial patterns in forests experiencing different fire histories between 1943 and 1994. C-HH, C-HV, L-HH, and L-HV band data were used to calculate mean backscatter (σ°) and several landscape metrics (e.g., largest patch index, mean patch size, edge density, and patch richness). We assessed the relationship between σ° and fire history, as well as spatial patterns and fire history. Significant (p < 0.05) results were obtained for landscape metrics derived from σ° and several fire history variables, although we did not find significant relationships (p < 0.05) between mean backscatter and fire occurrence.

Modeling the age of tropical moist forest fragments in heavily-cleared lowland landscapes of Colombia

Increasingly, large areas of native tropical forests are being transformed into a mosaic of human dominated land uses with scattered mature remnants and secondary forests. In general, at the end of the land clearing process, the landscape will have two forest components: a stable component of surviving mature forests, and a dynamic component of secondary forests of different ages. As the proportion of mature forests continues to decline, secondary forests play an increasing role in the conservation and restoration of biodiversity. This paper aims to predict and explain spatial and temporal patterns in the age of remnant mature and secondary forests in lowland Colombian landscapes. We analyse the age distributions of forest fragments, using detailed temporal land cover data derived from aerial photographs. Ordinal logistic regression analysis was applied to model the spatial dynamics of mature and secondary forest patches. In particular, the effect of soil fertility, accessibility and auto-correlated neighbourhood terms on forest age and time of isolation of remnant patches was assessed. In heavily transformed landscapes, forests account for approximately 8% of the total landscape area, of which three quarters are comprised of secondary forests. Secondary forest growth adjacent to mature forest patches increases mean patch size and core area, and therefore plays an important ecological role in maintaining landscape structure. The regression models show that forest age is positively associated with the amount of neighbouring forest, and negatively associated with the amount of neighbouring secondary vegetation, so the older the forest is the less secondary vegetation there is adjacent to it. Accessibility and soil fertility also have a negative but variable influence on the age of forest remnants. The probability of future clearing if current conditions hold is higher for regenerated than mature forests. The challenge of biodiversity conservation and restoration in dynamic and spatially heterogeneous landscape mosaics composed of mature and secondary forests is discussed.

Interpretation of land cover changes using aerial photography and satellite imagery in the Foothills Model Forest of Alberta

Aerial photographs acquired in 1948-1952, Corona "spy-satellite" imagery acquired in 1963, and Landsat multispectral scanner (MSS), thematic mapper (TM), and enhanced thematic mapper plus (ETM+) imagery acquired since 1974 were used to interpret land cover changes in the Foothills Model Forest of Alberta. The different image characteristics of aerial photographs and satellite sensor data require different analysis methods, but increasingly these data are being used together to determine changes in land cover and structure over a longer time period than is possible using satellite image data alone. The interpretations from this study suggest that in an active forest management area, conifer forest cover was reduced, broadleaf and mixed-forest cover was increased, and the forests were structured in smaller patches with greater edge density over the years circa 1950–1999. Another part of the study area, recovering from a major fire in the early part of the century, was interpreted to have experienced an increase in conifer forest area and mean patch size over this same time period. Overall, changes in the Foothills Model Forest landscape were relatively easily identified and deemed significant by resource managers; this study suggests additional work is warranted on understanding the effect of these changes in applications such as wildlife management.

The 7-Decade Degradation of a Large Freshwater Lake in Central Yangtze River, China

Freshwater lakes store water for human use and agricultural irrigation and provide habitats for aquatic fauna and flora. However, a number of these lakes have been degraded by human activities at a rapid rate. Here, we used historical land cover information and remotely sensed data to explore a 7-decade (between 1930s and 1998) shrinkage and fragmentation of Dongting Lake, the second largest freshwater lake in China, located in the drainage basin of Central Yangtze River. The water surface area of Dongting Lake decreased by 49.2%, from 4955 km2 in the 1930s to 2518 km2 in 1998, with an average decrease rate of 38.1 km2/yr in the past 7 decades. The lake was also fragmented, as indicated by a decreasing mean patch size from 4.2 km2 in the 1930s to 1.7 km2 in 1998. The degradation of the lake is largely attributed to a rapidly growing human population in the lake region that led to extensive impoldering. The degradation of the lake has resulted in negative ecological consequences, such as frequent flooding, a decline of biodiversity, and extinction of some endemic species. Our results also suggest that lake restoration projects implemented in this region since the end of the 1990s will help to decrease the lake degradation.

Spatial and Temporal Dynamics of a Restored Population of Oryza rufipogon in Huli Marsh, South China

Abstract Studying the process of population restoration is helpful for managing and preserving endangered species. A population of Oryza rufipogon (wild rice), an endangered species, was reintroduced in 1993 into Huli Marsh. We conducted a detailed survey over a 5‐year period (1997–2001) to evaluate the present status of the population and to further our understanding of its habitat requirements and the population model. The population was surveyed using 2 × 2–m quadrats in mid‐September of each year. In total, 2,683 quadrats were surveyed covering the whole O. rufipogon reserve during each survey. The population's spatial distribution was mapped, and the maps were used to examine the relationship between patch replacement and water depth. The individual number of O. rufipogon increased steadily from 1993 to 2001. The patch number, patch area, mean patch size, and largest patch size increased over this time period, and Korcak patchiness exponents decreased. On average, 83% of the patches persisted from one year to the next. There was a significant positive correlation between the initial patch size and the size the following year. The probability of patch disappearance decreased as patch size increased. Fifty‐eight percent of the patches were located at water depths between 20 and 30 cm. Water depth had no significant effect on the patch transition from O. rufipogon to other species. The loss and gain of O. rufipogon patches were statistically correlated with the patch areas in different water depths. Our results show that the population of O. rufipogon can successfully be reintroduced to the original habitat after appropriate environmental conditions have been restored. We recommend the following transplantation practices: transplant many smaller patches rather than a few larger patches, use transplant patch sizes of at least 20 m2, and transplant into sites vegetated with species with different regeneration niches from the transplanted species.

Assessing Relationships between Forest Spatial Patterns and Fire History with Fusion of Optical and Microwave Remote Sensing

In this paper, we tested the use of active and passive sensor fusion for relating forest fire history to landscape spatial patterns. Principal Components Analysis (PCA) was implemented to combine Landsat Thematic Mapper (TM) and Shuttle Imaging Radar (SIR-C) data from October 1994. Resulting PCs were converted to landscape patch maps. Plots with known fire history were delineated using a fire atlas of the study area. These plots came from four fire history categories: unburned (nine plots), once burned (three plots), twice burned (three plots), and multiple burned (three plots). Landscape metrics were calculated for each plot, including a shape index, mean patch size, Shannon's Diversity Index, and Shannon's Evenness Index. Spearman's Rank Correlation Analysis was used to compare the patch map‐derived landscape metrics to fire history characteristics, such as average fire‐free interval and number of fire‐free years in different time periods. Results showed that landscape patterns derived from fused data were significantly (p < 0.05) related to fire history and typically performed better than SIR-C data (a greater number of significant correlations), but not as well as TM data.

Targeting sites for habitat creation: an investigation into alternative scenarios

To date, habitat expansion in the United Kingdom has been on a case-by-case basis, without consideration of the current state, in terms of biodiversity, or the future sustainability of the habitat reserve. It was hypothesised that spatially targeted habitat expansion is beneficial for habitat and species’ persistence. Five spatially explicit scenarios for new habitat creation were devised, each with a different conservation aim: increase habitat patch size, reduce patch perimeter-area ratio, decrease habitat patch isolation, increase biodiversity and ensure sustainability. For beech woodlands in part of the Chilterns Natural Area, UK, we investigated changes to six landscape metrics (total area (TA), patch density (PD), largest patch index (LPI), mean patch size (MPS), mean nearest-neighbour distance (MNN) and mean shape index (MSI)) as a result of the addition of new habitat, in accordance with the level of increase indicated in the United Kingdom’s Habitat Action Plan for beech woodland. Significant differences were found between the landscape metrics produced by spatially targeting new habitat and those produced by randomly adding new habitat. Random habitat addition performed poorly when compared with spatially explicit habitat addition even with relatively modest habitat expansion targets. We conclude that spatial targeting of habitat creation can counter the adverse effects of habitat fragmentation.

Interpretation of scale in paired quadrat variance methods

AbstractQuestion: Previous interpretations of the variance plot of paired quadrat variance method (PQV) have been incomplete. The objective of this study was to clarify the interpretation of PQV, and to shed additional light on how different quadrat variance methods can be used, in concert, to measure scale in transect data.Methods: We used artificial and real data to examine how the PQVmethod elucidates spatial pattern. Two‐term local quadrat variance (TTLQV) and new local variance (NLV) methods, together with their three‐term counterparts, were also applied to the same data sets, and the results from all methods were compared.Results: When the mean gap size equalled the mean patch size along a transect, the first peak of the variance of PQV, NLV and TTLQV corresponded with the gap size (or patch size). However, if the mean gap size and patch size were unequal, the variance plot of PQV displayed a flat‐topped plateau, in which the first inflection represented the mean size of the smaller phase and the second inflection represented the mean size of the larger phase; TTLQV showed a clear peak and NLV displayed a distinct first peak while the second inflection was dampened. The results also indicated than the three‐term versions of quadrat variance methods did not consistently outperform their two‐term counterparts, and often confused the interpretation of scale.Conclusions: The quadrat variance methods associated with the patch‐gap measurements were able to efficiently detect not only the size of patches, but also the size of gaps.