Importance of functional classification in the use of carabids for the environmental risk assessment of the GE crops and other agricultural practices

Carabids(Coleoptera:Carabidae)seem to be suitable bioindicalors of the environmental impacts of novel agrotechnologies,including deployment of the genetically engineered(GE)crops.In this article,we describe our effort to employ carabids in the environmental risk assessment(ERA).GE maize MON88017,its near-isogenic hybrid nontreated or treated with the soil insccticide chlorpyrifos,and two reference hybrids were used to compare three different ways how to utilize carabids in ERA.The analysis of abundance of all captured carabids or of the most abundant carabid specics did not disclose any differences between the treatments.The analysis based on the categories of functional traits revealed distinct fecatures of some treatments and proved suitable for ERA because it permitted field data transportability in spite of different species compositions.Our results indicate that GE maize has no detrimental environmental effecl,On the other hand,we found significant trends toward lower abundance and lower species number(including analysis of all carabid species together)in plots treated with the insecticide,and some tendencies to higher abundance and higher species number in plots sown with the reference hybrid PR38N86.Using functional group indicators alows identification of unintended changes in ecological functions of agroecosystem and comparability across geographics.We recommend data evaluation at the level of the categories of functional traits in ERA of GE crops and other agricultural practices.     

How good are carabid beetles (Coleoptera,Carabidae) as indicators of invertebrate abundance and order richness?

Ground invertebrates were sampled by pitfall trapping on Brentmoor Heath, Surrey, UK during the summers of 2009 and 2010 to determine whether the abundance and species richness of carabids on bare ground patches are representative of invertebrate abundance and order richness on the same patches. Four patch sizes were investigated as well as the adjacent mown and unmown areas, and a range of environmental parameters were measured at each patch. Results show that increasing abundance and richness of carabids can give a broad indication of whether invertebrate abundance and order richness are increasing. Invertebrates in general are sensitive to a greater number of environmental variables and complex interactions than carabids are, due to the vast array of biological requirements of the large range of invertebrate species. All else being equal, smaller patches appear to benefit both carabid abundance and invertebrate abundance. Converse to the results of carabid species richness, larger patches appear to benefit invertebrate order richness. This study highlights the importance of testing the effect of habitat management strategies on a range of taxa rather than assuming the results for a bioindicator will suffice for management decisions. Whilst bioindicators may give a broad indication of effects on similar taxa, the precise nature of those effects will be determined by a number of species- and site-specific variables.     

Ground beetle (Coleoptera: Carabidae) assemblages in conventional and diversified crop rotation systems

Ground beetles (Coleoptera: Carabidae) are important in agro-ecosystems as generalist predators of invertebrate pests and weed seeds and as prey for larger animals. However, it is not well understood how cropping systems affect ground beetles. Over a 2-yr period, carabids were monitored two times per month using pitfall traps in a conventional chemical input, 2-yr, corn/soybean rotation system and a low input, 4-yr, corn/soybean/triticale-alfalfa/alfalfa rotation system. Carabid assemblages were largely dominated by a few species across all cropping treatments with Poecilus chalcites Say comprising >70% of pitfall catches in both years of study. Overall carabid activity density and species richness were higher in the low input, 4-yr rotation compared with the conventionally managed, 2-yr rotation. There were greater differences in the temporal activity density and species richness of carabids among crops than within corn and soybean treatments managed with different agrichemical inputs and soil disturbance regimes. Detrended correspondence analysis showed strong yearly variation in carabid assemblages in all cropping treatments. The increase in carabid activity density and species richness observed in the 4-yr crop rotation highlights the potential benefits of diverse crop habitats for carabids and the possibility for managing natural enemies by manipulating crop rotations.     

Landscape heterogeneity as an ecological filter of species traits

Landscape heterogeneity is a major driver of biodiversity in agricultural areas and represents an important parameter in conservation strategies. However, most landscape ecology studies measure gamma diversity of a single habitat type, despite the assessment of multiple habitats at a landscape scale being more appropriate. This study aimed to determine the effects of landscape composition and spatial configuration on life-history trait distribution in carabid beetle and herbaceous plant communities. Here, we assessed the gamma diversity of carabid beetles and plants by sampling three dominant habitats (woody habitats, grasslands and crops) across 20 landscapes in western France. RLQ and Fourth Corner three-table analyses were used to assess the association of dispersal, phenology, reproduction and trophic level traits with landscape characteristics. Landscape composition and configuration were both significant in explaining functional composition. Carabid beetles and plants showed similar response regarding phenology, i.e. open landscapes were associated with earlier breeding species. Carabid beetle dispersal traits exhibited the strongest relationship with landscape structure; for instance, large and apterous species preferentially inhabited woody landscapes, whereas small and macropterous species preferentially inhabited open landscapes. Heavy seeded plant species dominated in intensified agricultural landscapes (high % crops), possibly due to the removal of weeds (which are usually lightweight seeded species). The results of this study emphasise the roles of landscape composition and configuration as ecological filters and the importance of preserving a range of landscape types to maintain functional biodiversity at regional scales.     

Linking bird, carabid beetle and butterfly life-history traits to habitat fragmentation in mosaic landscapes

The goal of the present study is to assess how landscape configuration influenced the distribution of life-history traits across bird, carabid beetle and butterfly communities of mosaic forest landscapes in south-western France. A set of 12 traits was selected for each species, characterizing rarity, biogeographical distribution, body size, trophic guild, dispersal power, reproductive potential and phenology. We used a three-table ordination method, RLQ analysis, to link directly bird, beetle and butterfly traits to the same set of landscape metrics calculated in 400 m-radius buffers around sample points. RLQ analyses showed significant associations between life-history traits and landscape configuration for all three taxonomical groups. Threatened species from all groups were characterized by a combination of life traits that makes them especially sensitive to the fragmentation of herbaceous and shrub-dominated habitats at the landscape scale. These key life traits were low productivity, intermediate body mass, restricted geographic range, late phenology and ground gleaning for threatened birds, intermediate body size, spring adult activity, northern distribution and summer breeding period for threatened carabids, and restricted range, overwintering as eggs or larvae, low mobility, monophagy and short flight periods for threatened butterflies. Focusing on species life traits can provide a functional perspective, which helps to determine adequate measures for the conservation of threatened species and communities of several taxonomical groups in mosaic landscapes.     

Monitoring carabid indicators could reveal environmental impacts of genetically modified maize

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Life-history trait and functional diversity patterns of ground beetles and spiders along a coastal heathland successional gradient

We investigated patterns in species richness and diversity, life-history traits and functional diversity of carabid beetles and spiders along a coastal heathland successional gradient. We sampled in five successional stages on the island of Hiddensee, Germany. Species richness of carabids and spiders and Simpson diversity for spiders did not differ among stages. Functional dispersion (FDis), a measure of functional richness, was lowest in the youngest stage for both carabids and spiders. Older successional stages represent more heterogeneous habitats and offer a broader range of niches, which might enhance functional dispersion. Functional evenness (FEve) differed among successional stages for spiders, indicating an uneven distribution of species abundances in the functional trait space. Functional divergence (FDiv) did not differ among stages for either taxon. Shifts in life-history traits were noted in both arthropod groups, but not always in the same direction: Body size of carabid beetles increased towards older successional stages, but decreased for spiders. The number of flightless carabid species increased towards older habitats. Each successional stage seemingly favors species with distinct life-history traits (species sorting). We conclude that a trait-based approach including the use of functional diversity measurements (FDis) could contribute valuable information for biodiversity conservation.     

Islands in cities: Urbanization and fragmentation drive taxonomic and functional variation in ground arthropods

The conversion of natural lands in urban areas is exponentially increasing worldwide, causing a major decline in biodiversity. Environmental alterations caused by urbanization, such as land conversion and isolation of natural patches, favour tolerant and generalist species, causing both species loss and replacement. In addition, selective pressure is exerted on particular functional traits, driving a functional homogenization or turnover of biotic communities. We sampled ground arthropods within the municipality of Turin (NW-Italy), wherein an isolated and a connected control subplot were repeatedly sampled at 15 stations distributed along a gradient of increasing urbanization. Such a nested sampling design allowed us to investigate the taxonomic and the functional responses of carabids and spiders to both the urbanization level and patch isolation. First, we highlighted the dominant role played by species homogenization (nestedness) in explaining both taxonomic and functional variation in both groups of arthropods. Secondly, we showed that urbanization causes simultaneously functional homogenization and replacement in both carabid and spider assemblages, whereas patch isolation influences carabid species composition and homogenizes and shifts spider taxonomic and functional composition. Lastly, by relating community-weighted means of body length, dispersal capacity and trophic strategy to the urbanization and isolation gradients, we demonstrated that urbanization alters the trophic structure of both taxonomic groups and increases the average dispersal capacity of spiders. On the other hand, patch isolation affected the functional composition of spiders only, reducing the body size and increasing dispersal capacity and the proportion of web-builder species. Our results demonstrate that both urbanization and patch isolation alter species composition by causing functional and taxonomic homogenization. In addition, they exert a strong filtering effect on community functional traits, increasing the proportion of phytophagous species in carabids, and increasing dispersal capacity and web-builders occurrence in spiders, while reducing spider body size.     

Automated discovery of food webs from ecological data using logic-based machine learning

Networks of trophic links (food webs) are used to describe and understand mechanistic routes for translocation of energy (biomass) between species. However, a relatively low proportion of ecosystems have been studied using food web approaches due to difficulties in making observations on large numbers of species. In this paper we demonstrate that Machine Learning of food webs, using a logic-based approach called A/ILP, can generate plausible and testable food webs from field sample data. Our example data come from a national-scale Vortis suction sampling of invertebrates from arable fields in Great Britain. We found that 45 invertebrate species or taxa, representing approximately 25% of the sample and about 74% of the invertebrate individuals included in the learning, were hypothesized to be linked. As might be expected, detritivore Collembola were consistently the most important prey. Generalist and omnivorous carabid beetles were hypothesized to be the dominant predators of the system. We were, however, surprised by the importance of carabid larvae suggested by the machine learning as predators of a wide variety of prey. High probability links were hypothesized for widespread, potentially destabilizing, intra-guild predation; predictions that could be experimentally tested. Many of the high probability links in the model have already been observed or suggested for this system, supporting our contention that A/ILP learning can produce plausible food webs from sample data, independent of our preconceptions about "who eats whom." Well-characterised links in the literature correspond with links ascribed with high probability through A/ILP. We believe that this very general Machine Learning approach has great power and could be used to extend and test our current theories of agricultural ecosystem dynamics and function. In particular, we believe it could be used to support the development of a wider theory of ecosystem responses to environmental change.     

Belowground carabid beetle diversity in the western Palaearctic - effects of history and climate on range-restricted taxa (Coleoptera, Carabidae)

Broad-scale patterns of subterranean diversity are a fascinating but neglected part of biodiversity research. Carabid beetles adapted to belowground habitats form a particularly species-rich part of the subterranean fauna. We studied large-scale diversity patterns of these belowground carabids across the western Palaearctic and evaluated potential impacts of historical and contemporary environmental conditions on the distribution of these taxa, using available species richness and environmental data at country level. Regression modelling and variation partitioning showed a strong relationship between species richness and range in elevation. Potential effects of climatic variables, mainly those related to ambient energy input, were much weaker. We discuss the implications of this combination of effects, which suggests, concordant with the absence of subterranean carabids in northern and highest richness in southern Europe, a strong prevailing influence of historical processes on current richness distributions of these taxa. Previous studies did not provide clear indications for such an influence. In contrast to more mobile and widespread carabid beetles, dispersal limitation due to high adaptation of belowground carabids to subterranean habitats has probably hindered their re-colonization of former permafrost and glaciated regions. Hotspots of highest belowground diversity are located in regions with an assumed long-term stability of environmental conditions, correlating with patterns of other dispersal-limited taxa such as many endemic plants. Our study provides important new information in the discussion of potential determinants of the distinct geographic patterns of belowground diversity. Moreover, it contributes to a better understanding of range size related differences previously found in the distribution of diversity and environmental dependencies of widespread and range-restricted species within the highly diverse carabid beetles.     

Subsidies mediate interactions between communities across space

Most spatial ecology focuses on how species dispersal affects community dynamics and coexistence. Ecosystems, however, are also commonly connected by flows of resources. We experimentally tested how neighbouring communities indirectly influence each other in absence of dispersal, via resource exchanges. Using two‐patch microcosm meta‐ecosystems, we manipulated community composition and dynamics, by varying separately species key functional traits (autotroph versus heterotroph species and size of consumer species) and trophic structure of aquatic communities (species growing alone or in presence of competitors or predators). We then analysed the effects of species functional traits and trophic structure on communities connected through spatial subsidies in the absence of actual dispersal. Both functional traits and trophic structure strongly affected dynamics across neighbouring communities. Heterotroph communities connected to autotroph neighbours developed better than with heterotroph neighbours, such that coexistence of competitors was determined by the functional traits of the neighbouring community. Densities in autotroph communities were also strikingly higher when receiving subsidies from heterotroph communities compared to their own subsidies when grown in isolated ecosystems. In contrast, communities connected to predator‐dominated ecosystems collapsed, without any direct contact with the predators. Our results demonstrate that because community composition and structure modify the distribution of biomass within a community, they may also affect communities connected through subsidies through quantitative and qualitative changes of detritus flows. This stresses that ecosystem management should account for such interdependencies mediated by spatial subsidies, given that local community alterations cascade across space onto other ecosystems even if species dispersal is completely absent.     

Useful model organisms,indicators, or both? Ground beetles (Coleoptera,Carabidae) reflecting environmental conditions

Classic studies have successfully linked single-species abundances, life-history traits, assemblage structures and biomass of carabid beetles to past and present, human-caused environmental impacts and variation in ‘natural’ conditions. This evidence has led many to suggest carabids to function as ‘indicators’ − a term that bears multiple meanings. Here, a conservation-oriented definition for an indicator is used, carabid indicator potential from seven views is evaluated, and ways to proceed in indicator research are discussed. (1) Carabid species richness poorly indicates the richness and abundance of other taxa, which underlines the importance of using multiple taxa in environmental assessments. The ability of assemblage indices and specialist or functional-group abundances to reflect rare species and habitats should be examined in detail. (2) Experimental evidence suggests that carabids may potentially serve as keystone indicators. (3) Carabids are sensitive to human-altered abiotic conditions, such as pesticide use in agro-ecosystems and heavy metal contamination of soils. Carabids might thus reflect ecological sustainability and ‘ecosystem health’. (4) Carabid assemblages host abundant species characteristic of particular habitat types or successional stages, which makes them promising dominance indicators. (5) Carabids reflect variation in ‘natural’ conditions, but vegetation and structural features are more commonly adopted as condition indicators. Carabids nevertheless provide yet another, equally accurate, view on the structure of the environment. (6) Carabids may function as early-warning signalers, as suggested by recent studies linking climate and carabid distributions. (7) Carabids reflect natural and human-caused disturbances and management, but the usefulness of these responses for conservation purposes requires further research. In summary, European carabids appear useful model organisms and possibly indicators because they are diverse, taxonomically and ecologically well-known, efficiently reflect biotic and abiotic conditions, are relevant at multiple spatial scales, and are easy to collect in sufficiently large numbers to allow statistical analyses. The assumption that carabid responses would reflect rare environmental conditions or the responses of rare and threatened species ‒ crucial information for conservationists and managers ‒ has not yet been critically evaluated. Even if it holds, the usefulness will be context dependent: species and their populations vary, conditions vary, questions put forward vary, and assessment goals vary.     

Arable weeds in organically managed wheat fields foster carabid beetles by resource- and structure-mediated effects

Arable weeds in organically managed fields may foster arthropod generalist predators by the provision of shelter and favorable microclimate (structure-mediated effects) and the provision of additional animal and floral food resources (resource-mediated effects). In three organically managed winter wheat fields in Central Germany, we investigated the impact of weed removal and introduction of artificial weed-like structure on the activity density and species richness of carabid beetles with respect to trophic groups, microclimatic conditions, and densities of potential prey. Removal of weeds reduced both carabid activity density and species richness but did not affect trophic group composition. The decline in carabid activity density was dampened by the addition of artificial structure. Mean daily surface temperature and light intensity were significantly lower under weeds and artificial plants than under wheat plants alone. Weed removal reduced the abundance of leafhoppers and true bugs, but the response was inconsistent across fields. We conclude that the presence of arable weeds in organically managed wheat fields fosters carabid activity density and species richness via resource-mediated effects, such as a higher availability of weed-borne resources (e.g. seeds and pollen) and herbivorous prey. Structure-mediated effects (altering the microclimate) add to this positive effect. The presence of weeds in organically managed wheat fields enhances carabid activity density and diversity and needs to be integrated into future management strategies for natural enemy conservation.     

Progressively excluding mammals of different body size affects community and trait structure of ground beetles

Mammalian grazing induces changes in vegetation properties in grasslands, which can affect a wide variety of other animals including many arthropods. However, the impacts may depend on the type and body size of these mammals. Furthermore, how mammals influence functional trait syndromes of arthropod communities is not well known. We progressively excluded large (e.g. red deer, chamois), medium (e.g. alpine marmot, mountain hare), and small (e.g. mice) mammals using size‐selective fences in two vegetation types (short‐ and tall‐grass vegetation) of subalpine grasslands. We then assessed how these exclusions affected the community composition and functional traits of ground beetles (Coleoptera, Carabidae), and which vegetation characteristic mediated the observed effects. Total carabid biomass, the activity densities of carabids with specific traits (i.e. small eyes, short wings), the richness of small‐eyed species and the richness of herbivorous species were significantly higher when certain mammals were excluded compared to when all mammals had access, regardless of vegetation type. Excluding large and medium mammals increased the activity density of herbivorous carabid species, but only in short‐grass vegetation. Similarly, excluding large mammals (ungulates) altered carabid species composition in the short‐, but not in the tall‐grass vegetation. All these responses were related to aboveground plant biomass, but not to plant Shannon diversity or vegetation structural heterogeneity. Our results indicate that changes in aboveground plant biomass are key drivers of mammalian grazers’ influence on carabids, suggesting that bottom–up forces are important in subalpine grassland systems. The exclusion of ungulates provoked the strongest carabid response. Our results, however, also highlight the ecological significance of smaller herbivorous mammals. Our study furthermore shows that mammalian grazing not only altered carabid community composition, but also caused community‐wide functional trait shifts, which could potentially have a wider impact on species interactions and ecosystem functioning.     

Global meta‐analysis of native and nonindigenous trophic traits in aquatic ecosystems

Ecologists have recently devoted their attention to the study of species traits and their role in the establishment and spread of nonindigenous species (NIS). However, research efforts have mostly focused on studies of terrestrial taxa, with lesser attention being dedicated to aquatic species. Aquatic habitats comprise of interconnected waterways, as well as exclusive introduction vectors that allow unparalleled artificial transport of species and their propagules. Consequently, species traits that commonly facilitate biological invasions in terrestrial systems may not be as represented in aquatic environments. We provide a global meta‐analysis of studies conducted in both marine and freshwater habitats. We selected studies that conducted experiments with native and NIS under common environmental conditions to allow detailed comparisons among species traits. In addition, we explored whether different factors such as species relatedness, functional feeding groups, latitude, climate, and experimental conditions could be linked to predictive traits. Our results show that species with traits that enhance consumption and growth have a substantially increased probability of establishing and spreading when entering novel ecosystems. Moreover, traits associated with predatory avoidance were more prevalent in NIS and therefore favour invasive species in aquatic habitats. When we analysed NIS interacting with taxonomically distinctive native taxa, we found that consumption and growth were particularly important traits. This suggests that particular attention should be paid to newly introduced species for which there are no close relatives in the local biota. Finally, we found a bias towards studies conducted in temperate regions, and thus, more studies in other climatic regions are needed. We conclude that studies aiming at predicting future range shifts should consider trophic traits of aquatic NIS as these traits are indicative of multiple interacting mechanisms involved in promoting species invasions.     

Manipulating carabid beetle abundance alters prey removal rates in corn fields

Generalist natural enemies such as carabid beetles have the potential to maintain a variety of pests below outbreak levels in annual crops. To assess the relationship between carabid beetle abundance and field rates of prey removal, we created plots surrounded by different boundaries that selectively affected dispersal of edaphic arthropods, primarily carabids. Three treatments were established: (1) naturally occurring communities, (2) augmented communities using ingress boundaries, and (3) reduced communities using egress boundaries. Selective boundaries altered carabid communities with minimal habitat alteration and without use of insecticides. Three times during the growing season, a fixed number of onion fly pupae were placed in plots to evaluate the impact of carabid abundance on predation rates. A combination of vertebrate and invertebrate exclosures allowed us to evaluate prey removal by invertebrates alone. In comparison to the no boundary treatment, carabids increased 54.2% and decreased 83.1% in plots surrounded by ingress and egress boundaries respectively. Predation rates were positively correlated with carabid abundance (r² = 0.70, p < 0.0001). Significantly more pupae were removed from exclosures allowing access to invertebrates alone than from total exclosures, suggesting that invertebrates represented an important group of predators. Laboratory trials tested the feeding potential of the four most abundant carabid species and showed that they readily consumed onion fly pupae, supporting our hypothesis that carabids were the main predators in field tests. This study corroborates and extends previous observations of the importance of carabid beetles as generalist predators of insect pests in agricultural fields.     

The relative effects of local management and landscape context on weed seed predation and carabid functional groups

Farmland biodiversity and its associated ecosystem services are affected by agricultural activities at multiple spatial scales. Among these services, the regulation of weeds by invertebrate seed predators has received much attention recently but little is known about the relative effect of local management and landscape context of fields on this process. We monitored seed predation on four common weed species and carabid communities in 28 winter-cereals fields during five consecutive weeks in spring 2010. These fields were situated in contrasted landscape contexts and varied in terms of intensity of pesticide treatments and soil tillage regimes. Weed seed predation was strongly and positively related to the Shannon diversity of (strictly) granivorous carabids and to the activity–density of omnivorous carabids but negatively to the richness of omnivorous carabids. Weed seed predation and granivore diversity were positively related to landscape diversity and the proportion cover of temporary grassland within a 1000 m radius around focal fields and were negatively affected by the intensity of local pesticide treatments. No-till systems sheltered higher diversity of granivorous carabids but did not show higher seed predation rates. We showed that landscape composition factors had a higher relative influence than local practices factors on weed seed predation service. Consequently, weed management strategies should not only consider the management of single fields but also the surrounding landscape to preserve carabid biodiversity and enhance weed seed predation service.     

Seasonal variation in seed predation by adult carabid beetles

In many agro‐ecosystems of the temperate region, granivorous ground beetles (Coleoptera: Carabidae) are the most important invertebrate predators of seeds after dispersal. The consumption of a particular species of seed differs among carabid species, but seasonal variation in consumption has not yet been studied. Seasonal differences in the quantity of seed consumed by the carabids Harpalus affinis (Schrank) and Harpalus distinguendus (Duftschmid) were studied in a cafeteria experiment. Adults were collected on five dates between April and November and provided with seeds of 28 species of dicotyledonous herbaceous plants. Proportions eaten of the seeds offered (preferences) were nearly identical in both carabid species. Overall seed consumption increased from early spring until late June, then gradually decreased towards autumn. Despite this variation, the preferences on particular dates were essentially similar. Seasonal variation in carabid physiology and feeding experience thus influenced overall seed consumption, but not their preferences for particular seed species.     

Carabid beetles as indicators for shrub encroachment in dry grasslands

Semi-natural grasslands are key habitats for biodiversity conservation in Central Europe. Shrub encroachment is one of the most threatening drivers of grassland degradation and affects soil properties, microclimate, and vegetation with possible impacts on higher trophic levels. We aimed to analyse the impact of shrub encroachment with broom (Cytisus scoparius) on carabid beetle diversity, species composition, and functional traits. In a field study on dry grasslands on the island of Hiddensee (Germany) we studied 15 sites along a gradient of increasing broom encroachment and classified them into three dry grassland types with low, medium, and high shrub cover. Our results provide evidence that shrub encroachment initially has positive effects on species richness and activity densities of dry grassland carabids. Carabid species composition differed among differently shrub-covered dry grassland types, and sites with low and high shrub cover were each characterised by unique carabid assemblages. The species composition of sites with a medium shrub biomass had a transitional character and contained species which are typical for open dry grassland, but also shared species with sites with a high shrub cover. Among functional trait parameters investigated, especially the body size of carabid beetles was related to environmental parameters associated with shrub encroachment. Body size was positively correlated to shrub biomass and soil humidity, but negatively to temperature. Eurytopy values of carabids were related to high litter cover, i.e. habitat generalist (eurytopic) species mainly occurred in densely shrub-encroached sites. In order to preserve unique carabid assemblages of open dry grasslands with stenotopic and smaller species, it is most important to prevent a shrub encroachment higher than about 60% cover. For management we suggest extensive grazing (by cattle, sheep or horses) to prevent shrub encroachment on dry grasslands. In areas with high shrub cover additionally the use of goats or mechanical removal of shrubs might be necessary.