An Untidy Cover: Invasion of Bracken Fern in the Shifting Cultivation Systems of Southern Yucatán, Mexico

In land change science studies, a cover type is defined by land surface attributes, specifically including the types of vegetation, topography and human structures, which makes it difficult to characterize land cover as discrete classes. One of the challenges in characterizing a land-cover type is to distinguish variability within the class from actual land-cover transformation. The spread of plant invasions in tropical systems is affected by seasonal variations and disturbances such as agricultural activities and fires, making it difficult to determine the spread through thematic classifications. In this paper, we estimate the changes in spatial extent and seasonal variation of bracken fern invasion in Southern Yucatán from 1989 to 2005 by using a linear mixture model (LMM), a widely used method in the classification of remotely sensed data. The results show an increase in areas affected by bracken from 40 km² in 1989 to almost 80 km² in 2000. Lower estimates of the invasion resulted from data acquired at the end of the dry season (March–May), when bracken mixes with secondary vegetation or is removed by fires. The accuracy of the maps is estimated through the use of sketch maps of farmer's parcels and field data collected from 2000 to 2001. Understanding the spatial distribution and annual variability of bracken fern cover in the region is critical to determining the relation between disturbances such as fire and forest recovery. Using LMM may enhance this understanding by giving a more accurate picture of the extent and distribution of bracken fern invasion.
Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp     

Recovery of Moorland Vegetation after Aerial Spraying of Bracken (Pteridium aquilinum (L.) Kuhn) with Asulam

Bracken (Pteridium aquilinum) is a major weed of seminatural vegetation in Great Britain, as in many other countries. As a consequence, large areas have been subject to control with the intention of restoring the former vegetation. The use of aerial spraying with asulam, a narrow spectrum, carbamate herbicide, has become a common method of control. However, its long‐term efficacy has not been assessed in terms of either controlling the bracken or in producing suitable restored habitats. This study undertook such an assessment by comparing the results of a 2002 survey of the sites subject to bracken control by aerial spraying of asulam with previous (1990/1991 and 1994) surveys of the same sites. This showed that a single application of asulam was effective in eradicating bracken (<1% cover remaining) on a third of sites. However, on 10% of the sites, the bracken had regenerated completely (cover >80%) and on the remainder it was still present in patches (>20% of quadrats), often at high density. More than half the sprayed sites had seen good recovery of moorland vegetation, the target of the restoration, because they were now classified as having upland heathland vegetation within the National Vegetation Classification. Considerable amounts of bracken control are grant aided as part of agri‐environment schemes. These schemes should be adapted to encourage good practice, namely, intensive follow‐up treatment by spraying any emerging fronds, and to encourage treatment of previously sprayed areas rather than spraying of new areas in order to protect previous investment of grant aid.     

Degraded rangeland dominated by unpalatable forbs exhibits large-scale spatial heterogeneity

The spatial heterogeneity of vegetation and soil increases in response to land degradation caused by grazing mainly at a large spatial scale. This increase has been frequently associated with shrub invasion, but shrub invasion does not necessarily accompany land degradation. Instead, dominance by unpalatable forbs has been reported in some regions, but the spatial heterogeneity of such degraded rangeland has not been studied. We investigated the spatial heterogeneity of rangeland dominated by unpalatable forbs at a large spatial scale using Mongolian rangeland as an example. Spatial heterogeneity of the total vegetation cover and community heterogeneity were analyzed for three levels of land degradation. We found that the least-degraded site had homogeneous total vegetation cover and community, that the site with intermediate degradation exhibited low heterogeneity of the total vegetation cover but significant community type variation, and that the most degrade sites exhibited a periodic pattern of total vegetation cover as a result of a mixture of dense and sparse patches of unpalatable forbs. These different responses can be used to assess land degradation levels and may have potential to monitor land degradation at a large scale by satellite images.     

Effects of the litter layer of Pteridium aquilinum on seed banks under experimental restoration

Questions: Does the litter layer of Pteridium aquilinum (bracken) act as a barrier to certain species in the seed bank? Does bracken control/restoration treatment affect seed transfer through the litter layer? Location: Five experiments at three sites across the UK covering two major vegetation types; acid‐grassland and heath‐land. Methods: At each experiment a range of bracken control and vegetation restoration treatments were applied for about ten years. The seed bank was sampled in both the bracken litter and the soil. The cover (%) of each species in the vegetation and the bracken litter abundance (cover and depth) was also estimated. Results: The bracken litter layer acts as an inert barrier as it contained a large proportion of seeds available in the litter‐soil profile (38%– 67% of the total). Bracken litter depth and cover also influenced significantly the seed bank composition in both the bracken litter and the soil. These effects were site‐specific, and species‐specific. The application of treatments changed significantly the balance between seed inputs and outputs in the bracken litter layer for some species. This was either a positive or negative response relative to the untreated control plots. Conclusion: For heathland and acid‐grassland restoration, the bracken litter layer may be an important seed source, but it must be disturbed particularly before seed addition.     

Land‐use Change Dynamics,Soil Type and Species Forming Mono‐dominant Patches: the Case of Pteridium aquilinum in a Neotropical Rain Forest Region

Deforestation and agricultural land degradation in tropical regions can create conditions for growth of perennial plant species forming mono‐dominated patches (MDP). Such species might limit forest regeneration, and their proliferation forces the abandonment of fields and subsequent deforestation to establish new fields. Therefore, identifying factors fostering MDP species is critical for biodiversity conservation in human‐modified landscapes. Here, we propose a conceptual framework to identify such factors and apply it to the case of Pteridium aquilinum (bracken fern), a light‐demanding species, tolerant of low soil fertility and fire. We hypothesize that bracken proliferation is promoted by land‐use changes that increase light availability, especially in sites with low soil fertility and land uses involving fire. We assessed this idea using agricultural fields in southeastern Mexico with different land‐use change histories and quantifying prevalence and cover of bracken. Five different land‐use change histories resulted from transitions among forest, crop, pasture, and fallow field stages. Of the 133 fields sampled, 71 percent had P. aquilinum; regression tree analysis indicated that 65 percent of inter‐field variation in prevalence and 90 percent in cover was explained by land‐use change history and soil type. Maximum prevalence, cover, and rates of increase in bracken were found on fields with low fertility sandy/clay soils, which had been used for crops and pasture, were frequently burned, and had high levels of light. Fields on fertile alluvial soil never used for pasture were bracken‐free. Agriculture promoting high light environments on less fertile soils is a major cause of bracken proliferation and likely that of other MDP species.     

Woody vegetation structure of Brazilian Cerrado invaded by Pteridium arachnoideum (Kaulf.) Maxon (Dennstaedtiaceae)

Biological invasion is one of the major components of global change. In the Brazilian Cerrado, the fern Pteridium arachnoideum (neotropical bracken) is a potentially invasive species which is expected to change the vegetation structure of savannas. We assessed effects of the dominance of P. arachnoideum on the diversity of woody Cerrado species. We compared three sites dominated by neotropical bracken with three sites without neotropical bracken. We used multivariate analyses of variance and rarefaction curves with confidence limits to test whether the groups of species found in invaded areas were different from those found in non-invaded ones. We also analyzed the density of individuals and species and the mean area at breast height per plot. We found significant floristic differences between the areas. The diversity and the densities in the invaded areas were lower than in non-invaded ones. However, we did not observe differences in the mean area at breast height of woody plants. Thus, the P. arachnoideum invasion is a potential threat to Cerrado biodiversity. Management efforts should be made to control the bracken, since its dominance in the plant community may lead to impoverishment and simplification of the savanna vegetation.     

The distribution and abundance of

We examined the distribution and abundance of the invasive Hieracium species (hawkweeds) in the dry grasslands of the Upper Waitaki Basin (Canterbury) and Otago, using measures of Hieracium species frequency and hawkweed cover from 301 vegetation plots. Average hawkweed cover was significantly less in Otago than Canterbury. Hawkweed cover was also lower on drier sites, with hawkweeds having less cover at lower elevation, on more xeric sites and, in Canterbury, on soils with a lower moisture holding capacity. Environmental variables (elevation, moisture index, soil class, and measures of rabbit activity and the amount of recent pasture development) explained 43% of the variation in hawkweed cover in Canterbury, but only 25% in Otago. Furthermore, having controlled for environmental differences among plots, hawkweed cover in Otago was significantly spatially autocorrelated such that plots on the same property had similar hawkweed cover, but tended to differ from plots on other properties. This pattern is consistent with the hypothesis that variation in property management influenced the degree of hawkweed infestation. However, the same pattern was not found in Canterbury. We propose a general model to explain the observed patterns. The probability that a site will be invaded by hawkweeds is a function of: (1) the suitability of the site for hawkweed establishment (a function of the environment and past management), and (2) the size of the hawkweed propagule rain. The probability of hawkweed invasion is high when one or both of these variables have high values. Following initial invasion, there will be more local propagules coming from newly established plants and hawkweed cover at a site will increase, eventually stabilising at a level predictable from the environmental conditions at the site. This model predicts that the sites most suited for hawkweed establishment would be invaded first and fill the quickest. These susceptible sites would then serve as foci, providing propagules for subsequent hawkweed spread into adjacent, less invasion prone areas. The model predicts that the initial increase in hawkweed cover at a site should be exponential, and that there should be a lag in hawkweed spread whereby less susceptible sites are invaded later or at a slower rate. Both predictions are supported by data from monitoring trials. The model can explain the lower abundance of hawkweeds, the less predictable distribution of hawkweeds in relation to environmental variables, and the significant spatial autocorrelation in hawkweed cover in Otago compared to Canterbury, if hawkweed invasion in Otago is less complete than in Canterbury.     

Factors influencing patch occupancy and within‐patch habitat use in an apparently stable population of Willow Tits Poecile montanus kleinschmidti in Britain

Capsule Birds selected younger woodland patches with fewer conifers and higher soil moisture content; within these patches, they selected areas with higher vegetation cover at 2–4 m, and less bracken.

Aims For an apparently stable population, to investigate habitat differences between occupied and unoccupied woodland patches and habitat selection within occupied woodlands.

Methods We surveyed woodland patches for breeding Willow Tits in April 2006 in an area with an apparently stable population. Habitat was measured at points spread throughout each woodland patch and at points where Willow Tits were located. We compared habitat between occupied and unoccupied sites. In addition, within occupied sites, we examined habitat differences between Willow Tit locations and the points spread throughout the wood.

Results We surveyed 65 woodland patches, of which 29 were occupied. Willow Tits were more likely to be found in deciduous woodland that was younger and had higher levels of soil moisture. Probability of occupancy fell from 60% for woods aged 20–25 years to only around 15–30% for woods aged over 80 years. Within occupied woods, Willow Tits were more likely to be found in areas with more vegetation cover at the 2–4 m level and in areas with less bracken.

Conclusions Habitat management for Willow Tits should involve provision of young woodland patches with moist soils. Changes to the age structure and/or the soil moisture content of woods may be implicated in the dramatic decline of Willow Tits in Britain.     

基于SNIC-CNN-SVM模型的京津风沙源二期工程区土地利用/土地覆盖遥感识别研究

稀疏植被覆盖(草地、沙地、戈壁)演变能够直接表征区域生态环境和人类活动的动态影响变化。但由于大尺度稀疏植被区一般都具有地理跨度大,景观结构复杂多样,破碎化程度高,现有地表覆盖分类产品针对性不足等问题,使得该区域内林草沙的遥感提取难度较大,精度普遍偏低,直接制约生态效应评价模型的应用效果。因此,以典型大尺度稀疏植被区——京津风沙源治理二期工程区为研究区,研建了SNIC-CNN-SVM(SCS)模型,实现了大尺度稀疏植被区林草沙典型要素的信息自动提取和主要土地利用/土地覆盖类型识别。研究结果表明：1)引入惩罚性机制优化后的SNIC分割算法,有效提升了稀疏植被区与沙地区的边界区分度,有助于分类精度的提升;2)基于改进SNIC-CNN-SVM模型方案的研究区总体分类精度达89.41%,较优化前提高了11.17%,特别是乔、灌、草、沙地和戈壁的分类识别精度显著提升,表明该优化方案在以研究区为代表的稀疏植被区域分类中具有较好的应用效果和推广价值;3)分类结果显示,2020年工程区草地面积最大,占到了一半以上(51.52%),沙地占比11.96%,稀疏植被覆盖(草地、沙地、戈壁)区域占比68.68%...     

Species richness, diversity and biomass production of desert annuals in an ungrazed Rhanterium epapposum community over three growth seasons in Kuwait

Two blocks, each consisting of twelve 0.25 m²permanent plots, were established in a community dominated by desert annuals inan area of Kuwait protected from grazing, and community attributes wereinvestigated over three growth seasons. A linear relationship was found betweenestimated desert annual cover and biomass production. Species frequency wasassessed by the number of 100 cm² subplots occupied byaspecies in a block (block incidence). Over the three seasons,vegetation features varied considerably. The first season (spring 1997) wascharacterised by very sparse vegetation cover, low vegetation block incidence(sum of individual block incidences of each species present in a block) and lowspecies richness. The second season (spring 1998) had high vegetation cover,relatively low vegetation block incidence, but high species richness. In thethird season (spring 2000), vegetation cover was very sparse (as in 1997), butboth blocks had the highest vegetation block incidence of the three years andspecies richness was moderately high, although individual plants were verysmall. The growth period was much shorter in the very productive andspecies-rich 1998 season than in 2000. Fluctuations in biomass and speciesincidence coincided with pronounced variation in key meteorological variables,in particular the onset of the first rains, the amount of rainfall during thegrowing season and its temporal distribution. Species composition, however,appears mainly to be determined by the amount and possibly the timing of thefirst rainfalls of the season to trigger germination. There was little evidenceto suggest that particularly favourable or unfavourable microsites existed inplots for more than one vegetation period, either for individual species or fordiversity in general. Despite substantial between-season fluctuations inincidence, the relative abundances of the more frequent species to each otherremained broadly similar over the three seasons, with Plantagoboissieri being the predominant species and accounting for thelargest proportion of biomass.     

Lignin signatures show the effects of changes in heather and bracken cover on the composition of organic matter in a moorland soil profile

Bracken (Pteridium aquilinum) is aggressively displacing heather (Calluna vulgaris) on many moorlands in Britain. We investigated the use of lignin derivatives to identify the distribution of soil organic matter (SOM) derived from bracken in moorland soil profiles formed under heather. Phenylpropanoids extracted from recently senesced litters, roots and SOM, using alkaline CuO oxidation, showed distinct signatures for bracken and heather, with vanillyl moieties dominating bracken litter extracts and vanillyl and syringyl dominating heather litter extracts. Ratios of vanillyl and syringyl concentrations characterised the SOM derived from heather and bracken better than the concentrations of the individual moieties. The analysis showed up to a depth of 5 cm under pure bracken cover, and at the interface between heather and bracken, the SOM was largely derived from bracken litter but below that depth SOM was apparently derived from heather. The use of these methods to identify the plant origin of SOM not only enables understanding the effects of changing vegetation cover on organic matter dynamics in moorland soils but could also facilitate management techniques in moorland/heathland restoration which involve the removal of comparatively nutrient-rich SOM derived from bracken. Received: 30 November 1997 / Accepted: 11 April 1998     

Tree invasion into a mountain-top meadow in the Oregon Coast Range,USA

Abstract. The grassy meadow on the top of Marys Peak, in the Oregon Coast Range, is being invaded, primarily along the margins, by Abies procera. To examine vegetation and environmental changes across the forest-meadow transition and to evaluate factors affecting tree invasion, belt transects were established at 10 sites. Correlations of environmental variables with ordination axes from Detrended Correspondence Analysis suggest that the sites were distributed along a moisture gradient. Although the sites varied considerably in species composition and environment, tree invasion of the meadow was occurring at all sites. Reduction in abundance of the dense herbaceous vegetation of the meadow is required before the small seedlings of Abies procera can become established. Almost all tree invasion of the meadow occurs in the narrow forest-meadow ecocline because trees at the edge of the forest reduce the cover of herbaceous plants in the adjacent meadow. On some sites, above average snow accumulations further reduce vigor of meadow vegetation and increase tree establishment. On the driest sites wet summers facilitate tree establishment. Infrequent fires, which remove the fire sensitive Abies procera, are probably required to reverse the slow but persistent trend of forest expansion and ultimately maintain the meadow.     

Increase in nonnative understorey vegetation cover after nonnative conifer removal and passive restoration

Nonnative conifers are widespread in the southern hemisphere, where their use as plantation species has led to adverse ecosystem impacts sometimes intensified by invasion. Mechanical removal is a common strategy used to reduce or eliminate the negative impacts of nonnative conifers, and encourage native regeneration. However, a variety of factors may preclude active ecological restoration following removal. As a result, passive restoration – unassisted natural vegetation regeneration – is common following conifer removal. We asked, ‘what is the response of understorey cover to removal of nonnative conifer stands followed by passive restoration?' We sampled understorey cover in three site types: two‐ to ten‐year‐old clearcuts, native forest and current plantations. We then grouped understorey species by origin (native/nonnative) and growth form, and compared proportion and per cent cover of these groups as well as of bare ground and litter between the three site types. For clearcuts, we also analysed the effect of time since clearcut on the studied variables. We found that clearcuts had a significantly higher average proportion of nonnative understorey vegetation cover than native forest sites, where nonnative vegetation was nearly absent. The understorey of clearcut sites also averaged more overall vegetation cover and more nonnative vegetation cover (in particular nonnative shrubs and herbaceous species) than either plantation or native forest sites. Notably, 99% of nonnative shrub cover in clearcuts was the invasive nonnative species Scotch broom (Cytisus scoparius). After ten years of passive recovery since clearcutting, the proportion of understorey vegetation cover that is native has not increased and remains far below the proportion observed in native forest sites. Reduced natural regeneration capacity of the native ecosystem, presence of invasive species in the surrounding landscape and land‐use legacies from plantation forestry may inhibit native vegetation recovery and benefit opportunistic invasives, limiting the effectiveness of passive restoration in this context. Abstract in Spanish is available with online material.     

Nest and foraging‐site selection in Yellowhammers Emberiza citrinella: implications for chick provisioning

Capsule Vegetation structure and invertebrate abundance interact to influence both foraging sites and nestling provisioning rate; when invertebrate availability is low, adults may take greater risks to provide food for their young.

Aims To investigate nesting and foraging ecology in a declining farmland bird whose fledging success is influenced by the availability of invertebrate prey suitable for feeding to offspring, and where perceived predation risk during foraging can be mediated by vegetation structure.

Methods Provisioning rates of adult Yellowhammers feeding nestlings were measured at nests on arable farmland. Foraging sites were compared with control sites of both the same and different microhabitats; provisioning rate was related to habitat features of foraging‐sites.

Results Foraging sites had low vegetation density, probably enhancing detection of predators, or high invertebrate abundance at high vegetation density. Parental provisioning rate decreased with increasing vegetation cover at foraging sites with high invertebrate abundance; conversely, where invertebrate abundance was low, provisioning rate increased with increasing vegetation cover.

Conclusions Vegetation structure at foraging sites suggests that a trade‐off between predator detection and prey availability influences foraging site selection in Yellowhammers. Associations between parental provisioning rate and vegetation variables suggest that where invertebrate abundance is high birds increase time spent scanning for predators at higher vegetation densities; however, when prey are scarce, adults may take more risks to provide food for their young.     

Additive effects of climate and vegetation structure on the altitudinal distribution of greater white-toothed shrews Crocidura russula in a Mediterranean mountain range

Environmental variation along geographic gradients determines the distribution of animals and plants trough both direct and indirect effects. We analyze the relative contribution of climate and vegetation structure variations along a Mediterranean altitude gradient on the patterns of abundance and occurrence of the greater white-toothed shrew Crocidura russula, a generalist small mammal whose distribution is constrained by cold conditions. Sampling was performed from February 1995 to July 1997 on nine plots covering a wide altitudinal gradient (540–1550 m?a.s.l.). Structural equation models for the direct and indirect effects of climate and vegetation on shrew density and occupancy rates showed a stronger effect of vegetation structure (53 %) than direct climate effects (38 %) on shrew distribution. Shrews were more abundant in the warmer lowland sites, but were able to colonize highland cold areas by selecting habitats with well-developed understory vegetation (low shrubs or bracken). Vegetation effects were additive to climatic restrictions, seemingly providing more favorable microclimatic, and presumably food, conditions under shrub cover. Results indicate that predictions of range changes for shrews under climate change scenarios may underestimate expected range expansions under the current conditions of general land abandonment and shrub encroachment.     

Factors Affecting the Restoration of Heathland and Acid Grassland on Pteridium aquilinum–Infested Land across the United Kingdom: A Multisite Study

The variability in the success of Pteridium aquilinum (bracken) control and vegetation restoration has been highlighted as a major issue in the United Kingdom. Experiments were set up at four different regional locations to assess bracken control at the national scale and the impact of restoration practices at the local scale. Bracken control treatments (cutting once or twice per year, a combination of cutting and asulam spraying, and asulam in year 1) were combined with site‐specific treatments designed to restore appropriate heathland or acid grassland vegetation. This article considers the effects on the developing understorey vegetation, testing the following hypotheses: (1) local differences between sites would affect community change; (2) treatments applied to control Pt. aquilinum (same at all sites) influences community change; and (3) treatments applied at the individual site level to restore vegetation influences community change toward the target vegetation. There were a considerable number of spatial effects. It is, therefore, difficult to develop a one‐size‐fits‐all policy for vegetation restoration within a national Pt. aquilinum control strategy. Few bracken control treatment effects were found, and, where they were detected, it was only at single sites. Thus, the development of target vegetation requires a combination of control and restoration treatments that take into consideration the aspects of that site. Only three species, Deschampsia flexuosa, Galium saxatile, and Campylopus introflexus, increased as a direct effect of the control treatments. Vegetation restoration was most successful in the cutting‐twice‐per‐year plots, the treatment with the greatest reduction in Pt. aquilinum cover.     

European map of alien plant invasions based on the quantitative assessment across habitats

Aim Recent studies using vegetation plots have demonstrated that habitat type is a good predictor of the level of plant invasion, expressed as the proportion of alien to all species. At local scale, habitat types explain the level of invasion much better than alien propagule pressure. Moreover, it has been shown that patterns of habitat invasion are consistent among European regions with contrasting climates, biogeography, history and socioeconomic background. Here we use these findings as a basis for mapping the level of plant invasion in Europe. Location European Union and some adjacent countries. Methods We used 52,480 vegetation plots from Catalonia (NE Spain), Czech Republic and Great Britain to quantify the levels of invasion by neophytes (alien plant species introduced after ad 1500) in 33 habitat types. Then we estimated the proportion of each of these habitat types in CORINE land‐cover classes and calculated the level of invasion for each class. We projected the levels of invasion on the CORINE land‐cover map of Europe, extrapolating Catalonian data to the Mediterranean bioregion, Czech data to the Continental bioregion, British data to the British Isles and combined Czech–British data to the Atlantic and Boreal bioregions. Results The highest levels of invasion were predicted for agricultural, urban and industrial land‐cover classes, low levels for natural and semi‐natural grasslands and most woodlands, and the lowest levels for sclerophyllous vegetation, heathlands and peatlands. The resulting map of the level of invasion reflected the distribution of these land‐cover classes across Europe. Main conclusions High level of invasion is predicted in lowland areas of the temperate zone of western and central Europe and low level in the boreal zone and mountain regions across the continent. Low level of invasion is also predicted in the Mediterranean region except its coastline, river corridors and areas with irrigated agricultural land.     

A multi-site assessment of the effectiveness of Pteridium aquilinum control in Great Britain

Questions: The objectives of this study were to assess the effect of Pteridium aquilinum (bracken) control treatments, at the national scale, and the impact of restoration practices, at the local scale, on P. aquilinum performance. Hypotheses: 1. Geographical location (locally between and within sites) affects the control of P. aquilinum through time. 2. Are the P. aquilinum control treatments successful at all sites, and if so which ones? 3. The treatments applied at the individual site level to restore vegetation influences the performance of P. aquilinum through time. Location: Four geographically distinct acid grassland and heathland sites infested with P. aquilinum across Great Britain. Methods: Six main-plot, bracken control treatments were applied to all sites with site-specific vegetation restoration treatments. Response variables (P. aquilinum cover, frond length and density) were monitored twice yearly, in June and August between 1993 and 2003. Results: Between- and within-site spatial variation was found, although impact is perhaps less than suggested from shorter-term data. Despite local variation all sites responded similarly to bracken control treatments; asulam treatment resulted in a rapid reduction in frond performance followed by a continued recovery taking approximately ten years to return to untreated values. Cutting treatments tended to have a slower impact at the start but an increasing one over time, especially cutting twice per year. Restoration treatments had a limited impact; the only significant effect in August was grass seeding on frond length at Sourhope. In June only, the plots where sheep were fenced out showed a significant reduction in P. aquilinum cover at Peak. Conclusions: Long-term control of Pteridium aquilinum at all sites and on all measures was best achieved using a continuous cutting treatment, preferably twice per year.     

Gopher Tortoise Response to Habitat Management by Prescribed Burning

ABSTRACT As quality of forested habitat declines from altered fire regimes, gopher tortoises (Gopherus polyphemus) often move into ruderal areas to the detriment of the animal and land manager. We evaluated effects of a dormant-and-growing-season prescribed fire on habitat and gopher tortoise use of degraded longleaf pine (Pinus palustris) forests surrounding military training areas. We burned 4 of 8 sites in winter 2001–2002 and again in April 2003. Changes in vegetation measured during 2001–2004 indicated that burn treatments did not increase herbaceous vegetation. Similarly, movement patterns, burrow usage, and home range of tortoises radiotracked from 2002–2004 did not differ between treatments. Woody cover initially was reduced in the forests postburn, and we found more new burrows in burned forest sites. Once shrub cover was reduced, tortoises started using forested habitat that had become overgrown. However, shrub reduction may be temporary, as woody stem densities increased postburn. Thus, the one-time use of fire to manage tortoise habitat may not rapidly restore the open canopy, sparse woody midstory, and abundant herbaceous vegetation that this species requires. Repeated prescribed fires or additional management techniques may be needed for complete restoration.     

Random Forest characterization of upland vegetation and management burning from aerial imagery

Aim The upland moorlands of Great Britain form distinctive landscapes of international conservation importance, comprising mosaics of heathland, acid grassland, blanket bog and bracken. Much of this landscape is managed by rotational burning to create gamebird habitat and there is concern over whether this is driving long‐term changes in upland vegetation communities. However, the inaccessibility and scale of uplands means that monitoring changes in vegetation and burning practices is difficult. We aim to overcome this problem by developing methods to classify aerial imagery into high‐resolution maps of dominant vegetation cover, including the distribution of burns on managed grouse moors. Location  Peak District National Park, England, UK. Methods Colour and infrared aerial photographs were classified into seven dominant land‐cover classes using the Random Forest ensemble machine learning algorithm. In addition, heather (Calluna vulgaris) was further differentiated into growth phases, including sites that were newly burnt. We then analysed the distributions of the vegetation classes and managed burning using detrended correspondence analysis. Results Classification accuracy was c. 95% and produced a 5‐m resolution map for 514 km² of moorland. Cover classes were highly aggregated and strong nonlinear effects of elevation and slope and weaker effects of aspect and bedrock type were evident in structuring moorland vegetation communities. The classification revealed the spatial distribution of managed burning and suggested that relatively steep areas may be disproportionately burnt. Main conclusions Random Forest classification of aerial imagery is an efficient method for producing high‐resolution maps of upland vegetation. These may be used to monitor long‐term changes in vegetation and management burning and infer species–environment relationships and can therefore provide an important tool for effective conservation at the landscape scale.