Small Landscape Research Articles

Transformação da paisagem e o uso dos recursos florestais na agricultura familiar: um estudo de caso em área de Mata Atlântica

São Bonifácio está localizado na região das serras do leste catarinense, no bioma Mata Atlântica. A agricultura e a pecuária leiteira, praticadas na pequena propriedade, compõem o setor responsável por garantir ocupação da maior parte da população. Este estudo tem como objetivo analisar a relação entre agricultores familiares e os recursos florestais da paisagem. O estímulo a práticas produtivas que não valorizam a floresta associado à ausência de políticas de incentivo para o manejo florestal de espécies nativas, foram determinantes para a redução das áreas florestadas em São Bonifácio nas últimas cinco décadas.

Field, landscape and regional effects of farmland management on specialist open-land birds: Does body size matter?

Farmland birds have suffered significant declines in the last decades due to agricultural intensification. Agri-environment schemes (AES) aim to reverse this process by promoting “nature friendly” practises at the field-scale. AES based on the habitat requirements of target species have usually been successful, but the concurrence of species groups with contrasting habitat requirements (guilds) makes the design of successful measures for the whole bird community difficult. The effectiveness of AES is also constrained by landscape and regional effects not addressed by its field-scale application. Effects acting at different spatial scales could differ among bird species depending on basic life-history traits such home range size and landscape perception, which should covary with body size. We are not aware, however, of any study which investigates whether relative effects at different spatial scales could vary predictably within bird guilds. We analyse whether relative effects of within-field (including AES application), landscape and regional factors on open-land birds differ according to body size. Large birds were mostly affected by regional and landscape factors, whereas for small birds landscape and within-field factors were important. Hence, relative effects at changing spatial scales showed predictable variation according to bird size within this endangered and specialised farmland guild. These size-dependent effects should be taken into account for the design of more effective, integrated multi-scale strategies for the conservation of farmland birds.

The Clovis Occupation of the Dietz Site (35LK1529), Lake County, Oregon, and its Bearing on the Adaptive Diversity of Clovis Foragers

Archaeological models of Clovis adaptations are divided between those that argue for a single hunting adaptation characterized by high residential mobility without fixed territories and those that argue for a diversity of environment-specific adaptations and settlement systems. The Dietz site (35LK1529), the largest Clovis site in the Pacific Northwest, is composed of many overlapping, spatially coherent artifact clusters from which 75 whole and fragmentary fluted points have been recovered. The artifact assemblage is inconsistent with use of the site as a kill, camp, or quarry site. Geoarchaeological data show that the site area during the Clovis occupation was a sparsely vegetated, seasonal playa that is unlikely to have supported large herds of game animals. However, the site sits astride what was probably a major transportation corridor linking highly productive ecosystems in the adjoining basins, and Clovis foragers appear to have camped at Dietz repeatedly while traveling between these nearby basins. The systematic and redundant use of a geographically small landscape by Clovis foragers is inconsistent with expectations based on a model of residentially mobile foragers occupying new territories.

Landscape size affects the relative importance of habitat amount, habitat fragmentation, and matrix quality on forest birds

It is important to understand the relative effects of landscape habitat loss, habitat fragmentation, and matrix quality on biodiversity, so that potential management options can be appropriately ranked. However, their effects and relative importance may change with the size of the landscape considered because the multiple (and potentially conflicting) ecological processes that are influenced by landscape structure occur at different spatial scales (e.g. dispersal, predation, foraging). We estimated the relative effects of habitat loss, habitat fragmentation, and matrix quality (measured as the amount of forest, the proportion of forest area contained in large core forests, and the density of roads respectively) on fragmentation-sensitive forest birds in southern Ontario, Canada using a range of landscape sizes (0.8-310 km 2 ). We used three complementary statistical approaches to estimate relative effects of these correlated landscape factors - 1) multiple regression, 2) information theoretic (AIC) estimates of the most parsimonious model, and 3) multi-model inference to average effects across all supported models. We controlled for spatial autocorrelation, local habitat, roadside sampling bias, time of day, season, habitat heterogeneity, and the interaction between the effects of habitat amount and fragmentation. We found that relative effects of habitat amount and fragmentation were scale dependent; habitat amount had a consistently positive effect that was consistent over more than two orders of magnitude in landscape area (∼ 1―300 km 2 ). In contrast, the effects of habitat fragmentation depended on the size of the landscape considered. Indeed, for veery Catharus fuscescens, habitat fragmentation had positive effects at one scale and negative effects at another. The effects of matrix quality were generally weak and changed little with scale. For the number of fragmentation sensitive species and the presence of veery, habitat amount was most important in large landscapes and habitat fragmentation in small landscapes but for the presence of ovenbird Seiurus aurocapilla, habitat amount was most important at all scales.

‘For my children’: Different functions of the agricultural landscape and attitudes of farmers on different areas of Greece towards small scale landscape change

Geografisk Tidsskrift-Danish Journal of Geography 111(2):117–130, 2011 Agricultural landscapes are valued with different sets of criteria by different actors and stakeholders, including farmers, whose opinions and attitudes can vary greatly. In this paper, farmers' attitudes and opinions towards small scale landscape change in different areas of Greece (Koropi, Zagori and Lesvos) are presented. The areas are very different in terms of landscape and the driving forces of landscape change, with intense urban sprawl in Koropi urbanization in Mytilini and abandonment in Kentriko Zagori. The comparison of the attitudes, the evaluations and justifications farmers offer for landscape change is used to understand the dynamics of this change. Findings indicate that although common threads run through all the cases, conflicts between the different roles are evident and the attitudes reveal an antithesis between deep attachment to the land and farming traditions on the one hand and market pressures on the other, with important implications for rural and land use policies that have to encourage a better balance between these different roles.

Spatio-temporal variation of coarse woody debris input in woodland key habitats in central Sweden

The persistence of many saproxylic (wood-living) species depends on a readily available supply of coarse woody debris (CWD). Most studies of CWD inputs address stand-level patterns, despite the fact that many saproxylic species depend on landscape-level supplies of CWD. In the present study we used dated CWD inputs (tree mortality events) at each of 14 Norway spruce (Picea abies) dominated woodland key habitat sites to analyze the spatial and temporal patterns of CWD additions between 1950 and 2002 within a small landscape in central Sweden. We found that inputs were episodic within sites, where local windstorms created pulses in CWD input. Pulses occurred simultaneously in many sites, yielding landscape-level synchrony of CWD input. These synchronous pulses, and importantly, the breaks between pulses, may have negative implications for saproxylic species that are dependent on large volume inputs of freshly killed Norway spruce. In addition, the inherent small size and relative isolation of these sites may further increase extinction risks due to stochastic events. However, background CWD input rates occurring between pulses varied substantially among sites, presumably the result of the sites’ varied histories and structural characteristics. This finding suggests that the different sites have varied abilities to provide habitat for saproxylic species during periods with low landscape-level input of CWD.

Intensity of the anthropogenic effects on a small landscape unit in North Hungary

Intensity of the anthropogenic effects on a small landscape unit in North Hungary

ON THE PROBLEM OF TERRITORIAL DISTRIBUTION OF SAMPLE AREAS FOR LANDSCAPE MONITORING PURPOSES

Today landscape change monitoring becomes important in the field of sustainable development planning. Real changes of landscape have to be observed in a large scale (not smaller than 1:10,000) in order to avoid generalization of small landscape elements. In such a scale it is rational to perform the monitoring in sample areas that would be enough statistically abundant. The paper offers an original method of distributing the landscape sample areas in Lithuanian territory, differing from most methods based on random choose of sample areas though thorough analysis of the analogous methods abroad was performed. The work was sponsored by the Environmental Agency at the Lithuanian Ministry of Environment. In accordance to the spread of different natural landscape types (like clayey plains, morainic hills, sandy plains, etc.), a set of 100 sample areas (2.5 km2 each) was distributed in Lithuanian territory. To increase the sample area number in smaller landscape types (spit, coastal sandy plain, delta), some proportional corrections were made. Thus, the largest number of the sample areas was assigned to the most spread clayey plains (22), the smallest number – to sandy coastal plain (3). In order to find a concrete place for each sample area inside the landscape type a computer program was employed and the highest representation principle applied. Several tens of thousands possible positions of the sample areas were tested in order to find the best in representing land cover structure. This was achieved by calculating relative remoteness of tested samples’ land cover structure from the respective landscape type structure, further selecting the most patchy samples. Selecting the position of a sample area was also influenced by the buffer capacity (resistance to the chemical impact) of landscape, mostly concentrating on the areas with less buffer capacity (more sensitive to chemical pollution). Santrauka Tvariajai pletrai planuoti tampa aktualia kraštovaizdžio kaitos stebesena. Realūs kraštovaizdžio pokyčiai Lietuvos mastu turi būti fiksuojami stambiuoju masteliu (ne smulkesniu nei 1:10 000), vengiant nepageidautino smulkiu kraštovaizdžio elementu generalizavimo. Tokiu masteliu racionalu būtu pokyčiu stebejimus atlikti etalonuose, ju skaičius turetu būti statistiškai patikimas. Pateikiama originali kraštovaizdžio monitoringo etalonu išdestymo Lietuvos teritorijoje metodika. Darbas buvo atliktas remiant Aplinkos apsaugos agentūrai prie Lietuvos aplinkos ministerijos. Metodika parengta atsižvelgiant ir i užsienio šaliu patirti. Pagal kraštovaizdžio tipu paplitima proporcingai buvo išdalyta 100 2,5 km2 ploto etalonu, papildomai koreguojant (padidinant) etalonu skaičiu mažai paplitu‐siuose kraštovaizdžio tipuose (nerijoje, pajūrio lygumoje, deltoje). Taigi daugiausia etalonu (22) buvo skirta plačiausiai paplitusioms molingosioms lygumoms, mažiausiai (3) – pajūrio lygumai. Etalonams konkrečios vietos buvo parenkamos kompiuterine programa ir vadovautasi didžiausio reprezentatyvumo principu. Kiekvieno kraštovaizdžio tipo buvo išbandyta nuo keliu šimtu iki keliasdešimties tūkstančiu galimu etalonu padečiu, nustatyta pagal žemes dangos struktūra reprezentuojančios geriausiai. Etalonu vietu parinkimas buvo siejamas ir su kraštovaizdžio buferiškumo cheminei taršai arealais, daugiau koncentruojant mažesnio buferiškumo (jautresniuose cheminei taršai) plotuose. Резюме В настоящее время мониторинг изменений ландшафта становится актуальным для планировки сбалансированного развития. Реальные изменения ландшафта в Литве должны быть прослеживаемы в крупном масштабе (не мельче чем 1:10.000) во избежание нежелательной генерализации мелких структурных элементов ландшафта. В таком масштабе рационально осуществлять наблюдения на специально выделенных эталонных территориях, число которых должно быть статистически достаточным. В статье приведена методика расположения названных эталонов на территории Литвы. Работа выполнена при поддержке Агентства по охране окружающей среды при Министерстве окружающей среды. Методика разработана с учетом опыта зарубежных стран. С учетом распределения ландшафтных типов пропорционально было поделено сто эталонов площадью 2,5 км2 каждый. Дополнительно корректировалось (увеличивалось) число эталонов в мало распространенных ландшафтных типах (на косе, приморской равнине, в дельте). Наибольшее число эталонов (22) было отдано глинистым (наиболее распространенным) равнинам, а наименьшее (3) – приморской равнине. С целью подбоpa для эталонов конкретных мест была применена компьютерная программа, а также следовали принципу наивысшей репрезентативности. В каждом ландшафтном типе было испробовано от нескольких сот до нескольких десятков тысяч возможных положений эталонов с целью определить лучшее положение по репрезентативности земельно покровной структуры. Подбор мест для эталонов был осуществлен с учетом сопротивляемости ландшафта химическому загрязнению. Больше эталонов размещалось в наименее устойчивых ареалах.

Effects of overgrazing and rainfall variability on the dynamics of semiarid banded vegetation patterns: A simulation study with cellular automata

The effects of factors acting at small scale (grass/grass and grass/shrub biological interactions) and landscape scale (overgrazing and rainfall changes) on the development and permanence of banded vegetation patterns (VB) are assessed with a spatially explicit cellular automaton model. In particular, the influence of two environmental factors that are changing in many VB arid lands (rainfall and grazing pressures) is studied. Three rainfall regimes (representing 0.5, 1.0, and 2.0 times the long-term rainfall average), five grazing intensities, two types (reversible and irreversible) of grazing disturbance, two grazing periodicities (chronic and pulse), two levels of grass colonization ability, positive and negative interactions between shrubs and grasses, and the efficiency of endozoochorous seed dispersal are simulated. The results show that the permanence of undisturbed VB depends on the interaction of two factors, rainfall regime and grass colonization ability. Type and intensity of grazing also modify VB cover and permanence; furthermore, long-term overgrazing may convert mixed grass/shrub plant communities to pure scrublands dominated by endozoochorous-dispersed shrubs due to competitive interactions between shrubs and grasses. Besides providing an adequate representation of the system’s dynamics, the model is a useful tool that may be used to explore the consequences of climate change on management scenarios.

Landscape-scale conservation in practice: lessons from northern England, UK

Landscape-scale conservation projects are now Butterfly Conservation’s main delivery mechanism to conserve the UK’s threatened Lepidoptera. Butterfly Conservation currently works or has recently worked in 79 different landscapes targeted at key areas for threatened species, all of which involve partnerships with government agencies, other conservation organisations and landowners. Broadly we utilise two approaches firstly by providing advice to landowners and encouraging or assisting with the uptake of agri-environment or woodland grant schemes and secondly by securing external funding to directly undertake habitat management under the guidance of Butterfly Conservation project officers. These are not mutually exclusive with most projects having elements of both approaches. We describe two projects from northern England which utilise the direct funding approach and provide evidence for some of the lessons learnt by Butterfly Conservation’s 10 years experience of landscape-scale conservation delivery. From County Durham we demonstrate that for the Small Pearl-bordered Fritillary Boloria selene Denis & Schiff. it is possible to restore even very small fragmented landscapes. On the North York Moors we show that a non-equilibrium declining Duke of Burgundy Hamearis lucina L. metapopulation can be stabilised by carefully targeting restoration management, demonstrating the cost benefits of early intervention.

Evaluating management interventions in small populations of a perennial herbPrimula vulgarisusing spatio-temporal analyses of point patterns

Summary 1. In high-intensity agricultural landscapes, small landscape elements such as hedgerows, ditch banks, and rows of pollard trees may represent the last refuge of many plant and animal species, some of them being rare or even threatened with extinction. However, due to their small size and low habitat quality, long-term population survival cannot be ascertained and often active management is needed to maintain viable populations of species forced to survive in these small landscape elements. 2. Population models are needed to assess the threats to species at risk and to evaluate alternative management actions. Here, we present a methodology to evaluate management interventions using spatio-temporal analyses of point patterns. We apply this method to several populations of primrose Primula vulgaris in Flanders, where it is rare and predominantly occurs along ditch banks. 3. The effects of ditch bank clearing on the establishment success of seedlings was investigated by comparing spatial patterns of seedling recruitment, survival and mortality between populations that were grazed and populations that were severely disturbed by mechanical clearing of ditch banks followed by annual mowing. A total of 884 seedlings were mapped and monitored during 4 consecutive years (1999–2002). 4. In all populations, plants showed significant clustering, but in cleared sites only seedlings were significantly clustered around adults. Spatial patterns of mortality varied according to the management intervention. In grazed sites, mortality was almost random, whereas in cleared sites we found clear evidence for strong negative density-dependent mortality. There was no evidence that the presence of adults affected survival of recruits in any of the sites studied. 5. Synthesis and applications. This study shows that the analysis of spatial point patterns contributes to our understanding of the population dynamics of plant species occurring in different environments. The approach can be broadly applied to other plant species to elucidate the processes that determine the number of individuals that establish and persist into later life stages and will help conservation managers to refine management strategies intended to conserve or restore plant populations. In the case of P. vulgaris, increasing the availability of microsites is most likely to result in increased growth rates, as it results in increased recruitment and establishment of recruits.

Community-level enhancements of biodiversity and ecosystem services

A common management technique for preserving and maintaining biodiversity is the establishment of large refuges and preserves. Although extensive sanctuaries can provide crucial protection for many organisms and ecosystems, they cannot fulfill all the needs of regional conservation. An alternative to a few large refuges is to create many different habitats across the landscape that enhance and improve local and regional biodiversity and provide immediate benefits to nearby communities in the form of ecosystem services. Furthermore, these can all be initiated and achieved by individuals or communities. Some key landscape enhancements can be undertaken on a local level: the creation or expansion of small wooded areas, windbreaks, or hedgerows; the construction of small wetlands; and the release of some lands from heavy pressure for the reestablishment of natural ecological processes, namely, the natural accumulation of woody and other organic materials. Newly created ecosystems can be inoculated at the outset with soil biota such as seed banks, microbes, fungi, and organic material that can accelerate ecological functioning and balance. In addition to increasing much local and regional biodiversity, locally enhanced areas can provide fuel, plant and animal food and medicinal products, and agroforestry products directly to the nearby community. These small ecological oases can serve as nesting and overwintering sites for numerous pollinators that are hugely beneficial to agricultural production. Moreover, several ecosystem enhancements may contribute positively to local and regional hydrologic cycles and prevent prolonged droughts. Enhancements to local landscapes can take on many forms. We believe that any changes that increase structural complexity in natural systems almost certainly lead to increases in local biological complexity. In addition, wider landscape level considerations, such as corridors and connectivity of populations, can be integrated on a broader scale to improve regional biodiversity and ecosystem services. Small landscape enhancements undoubtedly cannot provide for all conservation needs, but they can greatly increase widespread biodiversity, restore local ecosystem services, and can be used to complement the relatively few larger parks.

A panel of microsatellites to individually identify leopards and its application to leopard monitoring in human dominated landscapes

BackgroundLeopards are the most widely distributed of the large cats, ranging from Africa to the Russian Far East. Because of habitat fragmentation, high human population densities and the inherent adaptability of this species, they now occupy landscapes close to human settlements. As a result, they are the most common species involved in human wildlife conflict in India, necessitating their monitoring. However, their elusive nature makes such monitoring difficult. Recent advances in DNA methods along with non-invasive sampling techniques can be used to monitor populations and individuals across large landscapes including human dominated ones. In this paper, we describe a DNA-based method for leopard individual identification where we used fecal DNA samples to obtain genetic material. Further, we apply our methods to non-invasive samples collected in a human-dominated landscape to estimate the minimum number of leopards in this human-leopard conflict area in Western India.ResultsIn this study, 25 of the 29 tested cross-specific microsatellite markers showed positive amplification in 37 wild-caught leopards. These loci revealed varied levels of polymorphism (four-12 alleles) and heterozygosity (0.05-0.79). Combining data on amplification success (including non-invasive samples) and locus specific polymorphisms, we showed that eight loci provide a sibling probability of identity of 0.0005, suggesting that this panel can be used to discriminate individuals in the wild. When this microsatellite panel was applied to fecal samples collected from a human-dominated landscape, we identified 7 individuals, with a sibling probability of identity of 0.001. Amplification success of field collected scats was up to 72%, and genotype error ranged from 0-7.4%.ConclusionOur results demonstrated that the selected panel of eight microsatellite loci can conclusively identify leopards from various kinds of biological samples. Our methods can be used to monitor leopards over small and large landscapes to assess population trends, as well as could be tested for population assignment in forensic applications.

Fast Folding of an RNA Tetraloop on a Rugged Energy Landscape Detected by a Stacking-Sensitive Probe

We investigate the microsecond-timescale kinetics of the RNA hairpin g a ∗ cUUCGguc. The fluorescent nucleotide 2-aminopurine ( a ∗ ) reports mainly on base stacking. Ten kinetic traces and the temperature denaturation curve are globally fitted to four-state models of the free-energy surface. In the best-fitting sequential model, the hairpin unfolds over successively larger barriers in at least three stages: stem fraying and increased base-stacking fluctuations; concerted loss of hydrogen bonding and partial unstacking; and additional unstacking of single strands at the highest temperatures. Parallel and trap models also provide adequate fits: such pathways probably also play a role in the complete free-energy surface of the hairpin. To interpret the model states structurally, 200 ns of molecular dynamics, including six temperature-jump simulations, were run. Although the sampling is by no means comprehensive, five different states were identified using hydrogen bonding and base stacking as reaction coordinates. The four to five states required to explain the experiments or simulations set a lower limit on the complexity of this small RNA hairpin's energy landscape.

Carbon pools and fluxes in small temperate forest landscapes: Variability and implications for sampling design

Assessing forest carbon storage and cycling over large areas is a growing challenge that is complicated by the inherent heterogeneity of forest systems. Field measurements must be conducted and analyzed appropriately to generate precise estimates at scales large enough for mapping or comparison with remote sensing data. In this study we examined spatial variability in three small temperate forest landscapes. Our objectives were (1) to quantify the magnitude and scale of variability in stand structure, carbon pools and carbon fluxes and (2) to assess how this variability influences both optimal sampling strategy and required sampling intensity. Stand structure was consistently less variable than carbon pools or fluxes, suggesting that measuring carbon dynamics may require more intense sampling than traditional forestry inventories. Likewise, the magnitude of variability differed substantially among response variables, implying that sampling efficiency can be enhanced by adopting a flexible sampling strategy that is optimized for each carbon pool. Our results indicate that plots dispersed across the study area are generally more effective than clustered plots for characterizing carbon dynamics.

Detrital carbon pools in temperate forests: magnitude and potential for landscape-scale assessment

Reliably estimating carbon storage and cycling in detrital biomass is an obstacle to carbon accounting. We examined carbon pools and fluxes in three small temperate forest landscapes to assess the magnitude of carbon stored in detrital biomass and determine whether detrital carbon storage is related to stand structural properties (leaf area, aboveground biomass, primary production) that can be estimated by remote sensing. We characterized these relationships with and without forest age as an additional predictive variable. Results depended on forest type. Carbon in dead woody debris was substantial at all sites, accounting for ∼17% of aboveground carbon, whereas carbon in forest floor was substantial in the subalpine Rocky Mountains (36% of aboveground carbon) and less important in northern hardwoods of New England and mixed forests of the upper Midwest (∼7%). Relationships to aboveground characteristics accounted for between 38% and 59% of the variability in carbon stored in forest floor and between 21% and 71% of the variability in carbon stored in dead woody material, indicating substantial differences among sites. Relating dead woody debris or forest floor carbon to other aboveground characteristics and (or) stand age may, in some forest types, provide a partial solution to the challenge of assessing fine-scale variability.

On the contribution of modelling to multifunctional agriculture: Learning from comparisons

In this paper a set of criteria is proposed for the evaluation of the potential contribution of modelling tools to strengthening the multifunctionality of agriculture. The four main areas of evaluation are (1) policy relevance, (2) the temporal resolution and scope, (3) the degree to which spatial and socio-institutional scales and heterogeneity are addressed and (4) the level of integration in the assessment of scientific dimensions and of the multiple functions of agriculture. The evaluative criteria are applied to the portfolio of modelling approaches developed and applied in a joint project of the French research institute INRA and the Dutch Wageningen University & Research Centre. The CLUE-S model focuses on prediction of changes in multifunctional land-use at regional scale, given a set of predetermined scenarios or policy variants, e.g. for ex-ante policy assessment and initiation of discussions on regional development. The two other modelling approaches are complementary and aim to address multifunctional farming activities. The Landscape IMAGES framework generates a range of static images of possible but sometimes distant futures for multifunctional farming activities in a small region or landscape. It supports the exploration of trade-offs between financial returns from agriculture, landscape quality, nature conservation and restoration, and environmental quality. Co-Viability Analysis generates trajectories of states and farming decisions fulfilling a given set of ecological and productive constraints representing a desired and sustainable future. The three modelling approaches differ in their policy relevance, in the ways that spatial and socio-institutional scales are addressed and in their degree of explicitation of interaction between the various functions of agriculture, but jointly cover most of the desired capabilities for assessment of multifunctionality. Caveats were particularly identified in the integration of the socio-institutional dimension and the related heterogeneity. Although the model portfolio did not completely satisfy the demands of the set of evaluative criteria, it is concluded that, due to their complementarities, in combination the three models could significantly contribute to further development and strengthening of multifunctionality.

The impact of landscape structure and sown grass margin strips on weed assemblages in arable crops and their boundaries

SummaryA paired‐field study was made in southern England in arable fields, each with or without sown 6‐m wide grass margin strips. Seven field pairs were located in each of small, intermediate and open landscapes, which were based on mean field size. Ground cover, plant species diversity and assemblages were assessed in crop centres, crop edges and non‐crop field boundaries. The data were used to test for effects of sown grass margins, differences in field location, impacts on rare weed species and for landscape effects on weed assemblages. Significantly higher plant species diversity was found in boundaries protected by buffer strips. Annual weeds associated with field edges, notably Anisantha sterilis, were found at lower cover where perennial grass strips were present. Sown grass strips enhanced boundary plant diversity, particularly by increasing polycarpic species. Margin strips had a small influence on the weed flora of the crop edge, possibly reducing weed cover, but had no influence on floras of field centres. Field size and landscape context did not affect weed assemblages, which show marked field‐to‐field variability, though crop type was an important influence. Grass margins did not enhance rare arable weed species and may be a threat to them, if margins are sited where such species are known to occur in the seedbank. With this exception, grass strips are a positive influence on boundary flora diversity and reduce margin weeds in arable landscapes.

Arthropod richness in roadside verges in the Netherlands

AbstractUrbanisation and intensification of agriculture has led to large scale destruction of natural and semi-natural areas in Western Europe. Consequentially, the conservation of biodiversity in small landscape units has become a matter of increasing urgency. In this paper, we inventoried the arthropod diversity in roadside verges in the Netherlands and studied the relative importance of these linear elements. In addition, the occurrence of arthropods in roadside verges in other countries was studied by literature research. In the period 1998-2008, we sampled 57 roadside verges. This was mainly done by pitfall trapping, using sweeping nets and insect nets, and by sight observations. For several arthropod groups the majority of the Dutch indigenous species was sampled: ants (56% of the indigenous species), grasshoppers (53%), harvestmen (67%) and two spider families (52% and 68%). For ground beetles, weevils, butterflies, bees, hoverflies and three other spider families, values between 18–41% were found. Considering that only a minute fraction of the vast network of roadsides was sampled, these figures are remarkably high. Roadside verges are occasionally reported to act as dispersal corridors for exotic species, but this could not be confirmed for arthropods in the Netherlands. Several of the arthropod species inventoried in the Dutch verges are classified as threatened: five grasshopper and eleven bee species appear on national Red Lists and six ant species on the IUCN Red List. Also, in several other countries roadside verges in intensively used landscapes appear to offer opportunities for arthropod conservation. We conclude that, if rightly managed, roadside verges can serve as an important and valuable arthropod habitat. Therefore, we strongly recommend taking always into account the conservation of these arthropod assemblages during planning and actual management of roadside verges.

A generalizable method for remote sensing of canopy nitrogen across a wide range of forest ecosystems

A growing number of investigations have shown that remote sensing of foliar nitrogen (N) concentration in plant canopies can be achieved with imaging spectroscopy, or hyperspectral remote sensing, from satellite or airborne sensors. Development of this approach has been fueled by recognition that foliar N is related to a variety of ecological and biogeochemical processes, ranging from the spread of invasive species to the ecosystem effects of insect defoliation events to patterns of N cycling in forest soils. To date, most studies have focused on building site-specific foliar N detection algorithms applied to individual scenes or small landscapes that have been intensively characterized with local field measurements. However, the growing number of well-measured sites, combined with improvements in image data quality and processing methods provide an opportunity to begin seeking more general N detection methods that can be applied to a broader range of sites or to locations that lack intensive field measurements. Here, we combine data from several independent efforts in North America, Central America and Australia, to examine whether development of calibration methods to determine canopy nitrogen concentration across a wide range of forest ecosystems is possible. The analysis included data from 137 individual field plots within eight study sites for which imagery has been acquired from NASA's Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and/or Hyperion instruments. The combined dataset was used to evaluate site-specific calibration results as well as results obtained with data pooled across all sites. We evaluated the accuracy of results using plot- and site-level cross-validation wherein individual plots or entire sites were withheld and used as an independent validation of the resulting algorithms. In instances where all sites were represented in the calibration, canopy-level foliar N concentration was predicted to within 7–15% of the mean field-measured values indicating a strong potential for broadly applied foliar N detection. When whole sites were iteratively dropped from the calibration and predicted by remaining data, predictions were still significant, but less accurate (7–47% of mean canopy-level N concentration). This suggests that further development to include a wider range of ecosystems will be necessary before cross-site prediction accuracy approaches that seen in site-specific calibrations. Nevertheless, we view these results as promising, particularly given the potential value of foliar N estimates, even at a reduced level of confidence, at sites for which there is no possibility of conducting field data collections.