How does habitat fragmentation affect the biodiversity and ecosystem functioning relationship?

Context

The relationship between biodiversity and ecosystem functioning (BEF) has been a central topic in ecology for more than 20 years. While experimental and theoretical studies have produced much knowledge of how biodiversity affects ecosystem functioning, it remains poorly understood how habitat fragmentation affects the BEF relationship.

Objectives

To develop a framework that connects habitat fragmentation to the BEF relationship from a landscape perspective.

Methods

We reviewed the literature on habitat fragmentation, BEF, and related fields, and developed a framework to analyze how habitat fragmentation affects the BEF relationship through altering biodiversity, environmental conditions, and both, based on the pattern-process-scale perspective in landscape ecology.

Results

Our synthesis of the literature suggests that habitat fragmentation can alter BEF relationship through several processes. First, habitat fragmentation causes the non-random loss of species that make major contributions to ecosystem functioning (decreasing sampling effect), and reduces mutualistic interactions (decreasing complementarity effects) regardless of the changes in species richness. Second, environmental conditions within patches and ecological flows among patches vary significantly with the degree of fragmentation, which potentially contributes to and modulates the BEF relationship.

Conclusions

Habitat fragmentation can affect the BEF relationship directly by altering community composition, as well as indirectly by changing environmental conditions within and among habitat patches on both local and landscape levels. The BEF relationship obtained from small plots and over short time periods may not fully represent that in real landscapes that are fragmented, dynamic, and continuously influenced by myriad human activities on different scales in time and space.

     

Butterfly assemblages in residential gardens are driven by species’ habitat preference and mobility

Context

Understanding the factors contributing to maintaining biodiversity is crucial to mitigate the impact of anthropogenic disturbances. Representing large proportions of green area in highly modified landscapes, residential gardens are often seen as local habitats that can contribute to larger networks of suitable environments at the landscape scale.

Objectives

We investigated the impact of the landscape context on butterfly communities observed in residential gardens, taking into account garden characteristics, land-use types and presence of linear features in the surrounding landscape. We examined how species traits affected butterflies’ response to landscape context and habitat quality.

Methods

We performed a cross-scale study, based on citizen science data documenting butterfly species composition and abundance in 920 gardens across France. We examined the effect of garden quality, the area of different land-use types and the length of linear elements measured at three scales within the surrounding landscape. Species were grouped according to their habitat preference and mobility.

Results

Urbanization negatively affected total species richness and the abundance of butterfly in each group. This was related to declining habitat quality and reduced area of suitable habitat in the surrounding landscape. The magnitude of this effect, however, was negatively correlated with mobility, a trait related to habitat preference. The spatial scale at which landscape context best explained variation in butterfly abundance changed with species’ habitat preference.

Conclusions

This study highlights the importance of preserving high quality habitats in altered landscapes and considering species’ mobility and habitat preference when assessing the impact of landscapes on butterfly communities.

     

Suburban habitats and their role for birds in the urban–rural habitat network: points of local invasion and extinction?

Suburban habitats in naturally forested areas present a conundrum in the urban–rural habitat network. Typically, these habitats contain less than half of the native woodland bird species that would exist at these sites if they were not developed. They also contain more total bird species than if these sites were left in a natural state. This apparent contradiction raises the question of “How do suburban habitats function in the urban–rural habitat network?” In this study, we analyze bird distributions on three rural-to-urban gradients in different ecoregions of the United States: Oxford, Ohio; Saint Paul, Minnesota; and Palo Alto, California. All three gradients exhibit similar patterns of extinction of native species followed by invasion of common species and subsequent biotic homogenization with urbanization. This patterning suggests that suburban land uses, those represented by the intermediate levels of development on the gradients, are a point of extirpation for woodland birds as well as an entry point for invasive species into urban systems. Furthermore, there are consistent patterns in the functional characteristics of the bird communities that also shift with intensifying urbanization, providing insight on the possible mechanisms of homogenization and community structure in urban ecosystems including an increase in the number of broods per year, a shift in nesting strategies, a decrease in insectivorous individuals, an increase in granivorous individuals, and a decrease in territoriality. Consequently, it appears that there are specific traits that drive the shift in community composition in response to urban and suburban land use. These results have significant implications for improving understanding of the mechanisms of suburban community ecology and conserving birds in urban habitat networks.     

Influence of habitat amount,arrangement, and use on population trend estimates of male Kirtland’s warblers

Kirtland’s warblers (Dendroica kirtlandii) persist in a naturally patchy environment of young, regenerating jack pine forests (i.e., 5–23 years old) created after wildfires and human logging activities. We examined how changing landscape structure from 26 years of forest management and wildfire disturbances influenced population size and spatial dispersion of male Kirtland’s warblers within their restricted breeding range in northern Lower Michigan, USA. The male Kirtland’s warbler population was six times larger in 2004 (1,322) compared to 1979 (205); the change was nonlinear with 1987 and 1994 identified as significant points of change. In 1987, the population trend began increasing after a slowly declining trend prior to 1987, and the rate of increase appeared to slow after 1994. Total amount of suitable habitat and the relative area of wildfire-regenerated habitat were the most important factors explaining population trend. Suitable habitat increased 149% primarily due to increasing plantations from forest management. The relative amount and location of wildfire-regenerated habitat modified the distribution of males among various habitat types, and the spatial variation in their abundance across the primary breeding range. These findings indicate that the Kirtland’s warbler male population shifted its use of habitat types temporally and spatially as the population increased and as the relative availability of habitats changed through time. We demonstrate that researchers and managers need to consider not only habitat quality, but the temporal and the spatial context of habitat availability and population levels when making habitat restoration decisions.     

Does habitat fragmentation affect landscape-level temperatures? A global analysis

Landscape Ecology - Habitat fragmentation per se (habitat subdivision independent of habitat loss) is a major driver of biodiversity change, potentially due to its impacts on climate. Habitat...     

How do local habitat management and landscape structure at different spatial scales affect fritillary butterfly distribution on fragmented wetlands?

Habitat fragmentation, patch quality and landscape structure are important predictors for species richness. However, conservation strategies targeting single species mainly focus on habitat patches and neglect possible effects of the surrounding landscape. This project assesses the impact of management, habitat fragmentation and landscape structure at different spatial scales on the distribution of three endangered butterfly species, Boloria selene, Boloria titania and Brenthis ino. We selected 36 study sites in the Swiss Alps differing in (1) the proportion of suitable habitat (i.e., wetlands); (2) the proportion of potential dispersal barriers (forest) in the surrounding landscape; (3) altitude; (4) habitat area and (5) management (mowing versus grazing). Three surveys per study site were conducted during the adult flight period to estimate occurrence and density of each species. For the best disperser B. selene the probability of occurrence was positively related to increasing proportion of wetland on a large spatial scale (radius: 4,000 m), for the medium disperser B. ino on an intermediate spatial scale (2,000 m) and for the poorest disperser B. titania on a small spatial scale (1,000 m). Nearby forest did not negatively affect butterfly species distribution but instead enhanced the probability of occurrence and the population density of B. titania. The fen-specialist B. selene had a higher probability of occurrence and higher population densities on grazed compared to mown fens. The altitude of the habitat patches affected the occurrence of the three species and increasing habitat area enhanced the probability of occurrence of B. selene and B. ino. We conclude that, the surrounding landscape is of relevance for species distribution, but management and habitat fragmentation are often more important. We suggest that butterfly conservation should not focus only on a patch scale, but also on a landscape scale, taking into account species-specific dispersal abilities.     

Riparian habitat changes across the continental United States (1972–2003) and potential implications for sustaining ecosystem services

Riparian ecosystems are important elements in landscapes that often provide a disproportionately wide range of ecosystem services and conservation benefits. Their protection and restoration have been one of the top environmental management priorities across the US over the last several years. Despite the level of concern, visibility and management effort, little is known about trends in riparian habitats. Moreover, little is known about whether or not cumulative efforts to restore and protect riparian zones and floodplains are affecting the rates of riparian habitat change nationwide. To address these issues, we analyzed riparian land cover change between the early 1970s and the late 1990s/early 2000s using existing spatial data on hydrography and land cover. This included an analysis of land cover changes within 180 m riparian buffer zones, and at catchment scales, for 42,363 catchments across 63 ecoregions of the continental US. The total amount of forest and natural land cover (forests, shrublands, wetlands) in riparian buffers declined by 0.7 and 0.9%, respectively across the entire study period. Gains in grassland/shrubland accounted for the 0.2% lower percentage of total natural land cover loss relative to forests. Conversely, urban and developed land cover (urban, agriculture, and mechanically disturbed lands) increased by more than 1.3% within riparian buffers across the entire study period. Despite these changes, we documented an opposite trend of increasing proportions of natural and forest land cover in riparian buffers versus the catchment scale. We surmise that this trend might reflect a combination of natural recovery and cumulative efforts to protect riparian ecosystems across the US. However, existing models limit our ability to assess the impacts of these changes on specific ecosystem services. We discuss the implications of changes observed in this study on the sustainability of ecosystem services. We also recommend opportunties for future riparian change assessments.     

Does the scale of our observational window affect our conclusions about correlations between endangered salmon populations and their habitat?

Differences in the strength of species-habitat relationships across scales provide insights into the mechanisms that drive these relationships and guidance for designing in situ monitoring programs, conservation efforts and mechanistic studies. The scale of our observation can also impact the strength of perceived relationships between animals and habitat conditions. We examined the relationship between geographic information system (GIS)-based landscape data and Endangered Species Act-listed anadromous Pacific salmon (Oncorhynchus spp.) populations in three subbasins of the Columbia River basin, USA. We characterized the landscape data and ran our models at three spatial scales: local (stream reach), intermediate (6th field hydrologic units directly in contact with a given reach) and catchment (entire drainage basin). We addressed three questions about the effect of scale on relationships between salmon and GIS representations of landscape conditions: (1) at which scale does each predictor best correlate with salmon redd density, (2) at which scale is overall model fit maximized, and (3) how does a mixed-scale model compare with single scale models (mixed-scale meaning models that contain variables characterized at different spatial scales)? We developed mixed models to identify relationships between redd density and candidate explanatory variables at each of these spatial scales. Predictor variables had the strongest relationships with redd density when they were summarized over the catchment scale. Meanwhile strong models could be developed using landscape variables summarized at only the local scale. Model performance did not improve when we used suites of potential predictors summarized over multiple scales. Relationships between species abundance and land use or intrinsic habitat suitability detected at one scale cannot necessarily be extrapolated to other scales. Therefore, habitat restoration efforts should take place in the context of conditions found in the associated watershed or landscape.     

Thailand’s catastrophic flood: Bangkok tree mortality as a function of taxa,habitat, and tree size

Urban areas have unique environments such as high air temperature, soil compaction and disturbance, and air and water pollution often impose plant stresses. Natural disasters can impose even greater stresses on plants in such areas. In 2011 Bangkok, Thailand experienced its worst flooding in over two decades, inundated up to a meter for a month. Here we report on tree tolerance to submerged, anoxic soils based on mortality. We identified over 6500 trees by taxa: 395 species in 219 genera within 60 families, which were categorized into three groups: susceptible (>50% mortality), tolerant (<50% mortality), and highly tolerant (no mortality). Among all the species, 18% were categorized as flood susceptible, 75% as tolerant, and 7% as highly tolerant. The floods resulted in decreased overall species richness by 18%, particularly in the Magnoliaceae and Lauraceae families, for which the mortality was 100% and 66%, respectively. Flood susceptible species were mostly from high rainfall habitats such as the hill evergreen forest. As expected, highly flood tolerant species were from the mangrove forests, beach/strand forests, and swamp plant communities, where the root zones are persistently saturated with lower quality water. Unexpectedly, many species native to higher temperature, drier, often deciduous lowland habitats were found to be flood tolerant, and were from the cultivated fruit and ornamental species. The results also indicated that smaller and younger trees suffered more mortality than larger and more mature trees. Therefore, during the tree selection process for planting in urban environments that may be at risk of frequent flooding, species from a wide spectrum of ecological habitats should be considered; particularly those characterized by one or more environmental stresses, such as drought, salt, heat, or saturated soils.     

Relative influence of local- and landscape-level habitat quality on aquatic plant diversity in shallow open-water wetlands in Alberta’s boreal zone: direct and indirect effects

Reclamation usually involves modification of the local environment to achieve some biotic target, but if the influence of Landscape Condition on that target is great, we may fail to meet it despite efforts at the local-level. We sought to determine the relative influence of local- and landscape-level habitat on aquatic plant diversity in shallow open-water wetlands. Furthermore, we asked whether the influence of Landscape Condition should be attributed to direct (dispersal-related) effects, or to the indirect effect of landscape variables that influence local habitat quality. Finally, we asked if spatial scale (300–2000 m) would affect conclusions about the relative influence of local- and landscape-level effects. Using structural equation modeling, we found that Local Condition is consistently more influential than Landscape Condition. As landscape size increases, the relative importance of Landscape Condition declines and there is a trade-off between its direct and indirect components. At ≤500 m direct landscape effects were of greater importance than indirect effects, whereas indirect effects of Landscape Condition became more important at ≥1500 m. This suggests that the dominant mechanism by which land use influences diversity depends on the spatial extent of the landscape. We recommend that reclamation designs include a high proportion of wetland habitat and incorporate seeding/planting if diverse plant communities are desired. Additionally, we note that the influence of the landscape is strongest within 300 m. Thus, the focus of reclamation efforts should remain at the in-lake level and the immediate surroundings: this is where efforts will achieve the greatest effect on aquatic plant diversity.     

Using an individual-based model to examine the roles of habitat fragmentation and behavior on predator–prey relationships in seagrass landscapes

Seagrasses, which form critical subtidal habitats for marine organisms worldwide, are fragmented via natural processes but are increasingly being fragmented and degraded by boating, fishing, and coastal development. We constructed an individual-based model to test how habitat fragmentation and loss influenced predator–prey interactions and cohort size for a group of settling juvenile blue crabs (Callinectes sapidus Rathbun) in seagrass landscapes. Using results from field studies suggesting that strong top-down processes influence the relationship between cannibalistic blue crab populations and seagrass landscape structure, we constructed a model in which prey (juvenile blue crabs) are eaten by mesopredators (larger blue crabs) which in turn are eaten by top-level predators (e.g., large fishes). In our model, we varied the following parameters within four increasingly fragmented seagrass landscapes to test for their relative effects on cohort size: juvenile blue crab (prey) predator avoidance response, hunting ability of mesopredators and predators, the presence of a top-level predator, and prey settlement routines. Generally, prey cohort size was maximized in the presence of top-level predators and when mesopredators and predators exhibited random searching behavior vs. directed hunting. Cohort size for stationary (tethered) prey was maximized in fragmented landscapes, which corresponds to results from field experiments, whereas mobile prey able to detect and avoid predators had higher survival in continuous landscapes. Prey settlement patterns had relatively small influences on cohort size. We conclude that the effects of seagrass fragmentation and loss on organisms such as blue crabs will depend heavily on behaviors of prey and predatory organisms and how these behaviors change with landscape structure.     

Landscape,fire and habitat: which features of recently burned heathland influence site occupancy of an early successional specialist?

Context

Multiple ecological drivers generate spatial patterns in species’ distributions. Changes to natural disturbance regimes can place early successional habitat specialists at an increased risk of extinction by altering landscape patterns of habitat suitability.

Objectives

We developed a series of hypotheses to evaluate the effects of landscape structure, fire history, and site-level habitat quality on site occupancy by an early successional specialist, the eastern chestnut mouse (Pseudomys gracilicaudatus).

Methods

We obtained eight years of monitoring data from 26 sites in recently burned heathland in southeast Australia. We used generalised linear models to determine which explanatory variables were related to occupancy. We also explored predictability in patterns of small mammal species co-occurrence.

Results

Landscape structure (patch area, landscape heterogeneity) was strongly related to site occupancy. Site occupancy was associated with dead shrubs in the understory and rock cover on ground layer, but was not directly influenced by recent or historical fire. Contrary to contemporary ecological theory, we found no predictable species associations in our early successional community.

Conclusions

We recommend surveys take account of landscape configuration and proximity to suitable habitat for optimal results. Fire regimes expected to promote eastern chestnut mouse population growth should encourage the retention of critical habitat features rather than be based on temporal rates of successional stages. For management to adequately account for post-disturbance patterns in early successional communities, a species-by-species, multi-scaled approach to research is necessary.

     

Seasonal and temporal changes in species use of the landscape: how do they impact the inferences from multi-scale habitat modeling?

Context

Multi-scale approaches to habitat modeling have been shown to provide more accurate understanding and predictions of species-habitat associations. It remains however unexplored how spatial and temporal variations in habitat use may affect multi-scale habitat modeling.

Objectives

We aimed at assessing how seasonal and temporal differences in species habitat use and distribution impact operational scales, variable influence, habitat suitability spatial patterns, and performance of multi-scale models.

Methods

We evaluated the environmental factors driving brown bear habitat relationships in the Cantabrian Range (Spain) based on species presence records (ground observations) for the period 2000–2010, LiDAR data on forest structure, and seasonal estimates of foraging resources. We separately developed multi-scale habitat models for (i) each season (spring, summer, fall and winter) (ii) two sub-periods with different population status: 2000–2004 (with brown bear distribution restricted to the main population nuclei) and 2005–2010 (with expanding bear population and range); and (iii) the entire 2000–2010 period.

Results

Scales of effect remained considerably stable across seasonal and temporal variations, but not the influence of certain environmental variables. The predictive ability of multi-scale models was lower in the seasons or periods in which populations used larger areas and a broader variety of environmental conditions. Seasonal estimates of foraging resources, together with LiDAR data, appeared to improve the performance of multi-scale habitat models.

Conclusions

We highlight that the understanding of multi-scale behavioral responses of species to spatial patterns that continually shift over time may be essential to unravel habitat relationships and produce reliable estimates of species distributions.

     

Connectivity or area: what drives plant species richness in habitat corridors?

Context

The relative importance of habitat area and connectivity for species richness is often unknown. Connectivity effects may be confounded with area effects or they may be of minor importance as posited by the habitat-amount hypothesis.

Objectives

We studied effects of habitat area and connectivity of linear landscape elements for plant species richness at plot level. We hypothesized that connectivity of linear landscape elements, assessed by resistance distance, has a positive effect on species richness beyond the effect of area and, further, that the relative importance of connectivity varies among groups of species with different habitat preferences and dispersal syndromes.

Methods

We surveyed plant species richness in 50 plots (25 m²) located on open linear landscape elements (field margins, ditches) in eight study areas of 1 km² in agricultural landscapes of Northwest Germany. We calculated the area of linear landscape elements and assessed their connectivity using resistance distance within circular buffers (500 m) around the plots. Effects of area and connectivity on species richness were modelled with generalised linear mixed models.

Results

Species richness did not increase with area. Resistance distance had significant negative effects on total richness and on the richness of typical species of grasslands and wetlands. Regarding dispersal syndromes, resistance distance had negative effects on the richness of species with short-distance, long-distance and aquatic dispersal. The significant effects of resistance distance indicated that species richness increased with connectivity of the network of linear landscape elements.

Conclusions

Connectivity is more important for plant species richness in linear landscape elements than area. In particular, the richness of plant species that are dispersal limited and confined to semi-natural habitats benefits from connective networks of linear landscape elements in agricultural landscapes.

     

Small forest patches as pollinator habitat: oases in an agricultural desert?

Landscape Ecology - Small forest fragments are often the most abundant type of semi-natural habitat in intensive agricultural landscapes. Wild pollinators can use these forest patches as nesting or...     

The effects of the number,size and isolation of patches along a gradient of native vegetation cover: how can we increment habitat availability?

Habitat availability—or how much habitat species can reach at the landscape scale—depends primarily on the percentage of native cover. However, attributes of landscape configuration such as the number, size and isolation of habitat patches may have complementary effects on habitat availability, with implications for the management of landscapes. Here, we determined whether, and at which percentages of native cover, the number, size and isolation of patches contribute for habitat availability. We quantified habitat availability in 325 landscapes spread across the state of Rio de Janeiro, in the Atlantic Forest hotspot, with either high (>50 %), intermediate (50–30 %), low (30–10 %) or very low (<10 %) percentage of native cover, and for six hypothetical species differing in inter-patch dispersal ability. Above 50 % of native cover, the percentage of cover per se was the only determinant of habitat availability, but below 50 % the attributes of landscape configuration also contributed for habitat availability. The number of patches had a negative effect on habitat availability in landscapes with 50–10 % of native cover, whereas patch size had a positive effect in landscapes with <10 % of native cover. The different species generally responded to the same set of landscape attributes, although to different extents, potentially facilitating decision making for conservation. In landscapes with >50 % of native cover, conservation actions are probably sufficient to guarantee habitat availability, whereas in the remaining landscapes additional restoration efforts are needed, especially to reconnect and/or enlarge remaining habitat patches.     

Nonlinear effects of distance to habitat edge on Sprague’s pipits in southern Alberta,Canada

Effects of habitat edge may influence habitat quality, but landscape-scale implications of edge effects have rarely been quantified. Sprague’s pipit (Anthus spragueii), a grassland obligate songbird, is declining rapidly throughout its range. Although habitat loss is implicated in the decline, the causes are not well understood. We conducted 290 point counts across a 120 × 130 km study area in southern Alberta, Canada, between 2000 and 2002, and used nonlinear regression to determine effects of distance to water, roads, and cropland or forage habitats on relative abundance of Sprague’s pipits. We then used a geographic information system (GIS) to determine the effect of edges on habitat suitability as indexed by relative abundance. Sprague’s pipit relative abundances declined by 25% from the maximum predicted relative abundance within 900 m (CI = 660–1,280) of croplands or forage crops, and 340 m (CI = 280–460) of wetlands, but there was no effect of roads. Fewer than 1% of grassland patches in the study area contained any habitat far enough away from edge that they would be predicted to support at least 75% of the relative abundance of pipits expected in the absence of edge effects. Only 33% of the landscape can support 75% or more of the relative abundance expected in the absence of edge effects, as a result of habitat conversion or edge effects. Sprague’s pipit populations may be declining in part because edge effects greatly magnify effects of habitat loss.     

Species-dependent effects of habitat degradation in relation to seasonal distribution of migratory waterfowl in the East Asian–Australasian Flyway

Landscape Ecology - Migratory species’ resilience to landscape changes depends on spatial patterns of habitat degradation in relation to their migratory movements, such as the distance...     

What multiscale environmental drivers can best be discriminated from a habitat index derived from a remotely sensed vegetation time series?

Understanding which environmental conditions are critical for species survival is a critical, ongoing question in ecology. These conditions can range from climate, at the broadest scale, through to elevation and other local landscape conditions, to fine scale landscape patterns of land cover and use. Remote sensing is an ideal technology to monitor and assess changes in these environmental conditions at a variety of spatial and temporal scales, with many studies focusing on the physiological state of vegetation derived from time series of satellite measurements. As vegetation occurs within specific climatic zones, over certain soil, terrain, and land cover types, it can be difficult to decipher the influence of the underlying role of climate, topography, soil, and land cover on the observed vegetation signal. In this article, we specifically addressed this problem by asking the question: what is the relative impact and importance of these different scales of environmental drivers on the temporal and spatial patterns observed on a habitat index derived from remotely sensed data? To find the solution, we utilized a SPOT VEGETATION-normalized difference vegetation index time series of Europe to create a remote-sensing-derived habitat index, which incorporates aspects of productivity, seasonality, and cover. We then compared the observed temporal and spatial variations in the index to a pan-Europe terrestrial classification system, which explicitly incorporates variations in climate, terrain, soil parent material, land cover, and use. Results indicated that the most accurate level of discrimination from the habitat index was at the broadest level of the hierarchy, climate, while the poorest degree of discrimination was associated with elevation. In terms of similarity on the index across time and space, we found that arable and forest cover classes were more similar across elevation and parent materials than across other land cover types within them. Analyzing the remote-sensing index, at multiple scales, provides significant insights into the drivers of satellite-derived greenness indices, as well as highlights the benefit and cautions associated with linking satellite-derived indirect indicators to species distribution modeling and biodiversity.     

Does intensive cutting regime maintain lowland dry heathlands habitat? The case study of Milano Malpensa airport (Northern Italy)

Airports are anthropogenic settlements which can harbour large portions of open habitats, including grasslands, which may host high species richness. Milano Malpensa Airport is the second main Italian airfield. One of its main open habitats is lowland dry heathland, frequently mown to fulfil aircraft safety requirements. The same habitat was formerly common in the surroundings of the airport, but it is nowadays endangered by management cessation and consequent tree (mainly Prunus serotina) encroachment. We compared heathland structure and vegetation composition in Calluna vulgaris populations within Malpensa Airport and outside it, where three degradation stages (identified by increasing P. serotina encroachments) were studied. We performed 52 surveys (10 within the airport, 18 in the less encroached heathland, 12 in the intermediate, and 12 in the most encroached) where we visually estimated the percentage cover of all plant species and we assessed heather density and height. Heathlands inside the airport (subjected to up to two cuts per year at 5 cm above ground) were richer in plant species and with a higher rejuvenation rate, but with a relevant cover of alien species and of plants typical of more intensive and disturbed grasslands. Among the heathlands outside the airfield, the two with the highest encroachment harboured few, tall, degenerate heather individuals, and were invaded by P. serotina and Molinia arundinacea. Among all, the heathland showing the best habitat conservation status was that outside the airport with the lowest P. serotina encroachment. There, heather population structure assumed a typical shape of young communities, likely due to the high light availability related to the low tree species cover. Additionally, the limited presence of bare soil compared to heathland inside Malpensa likely hampered the colonization by both alien species and pioneer plants of other environments. These outcomes showed that an intensive cutting regime in lowland dry heathlands can counteract habitat loss due to tree encroachment, which has been confirmed as one of the main threats to its conservation. However, cut frequency and height should be carefully determined to hinder the expansion of plants belonging to other habitats while encouraging the typical floristic composition.