Use Of Hedgerows Research Articles

The use of hedgerows to mitigate pesticide exposure of a population living in a rural area.

Farmer populations living in houses inside vegetable gardens are exposed to indoor pesticide pollution. The pulverization drift and volatile pesticides transported by wind are important sources of indoor pollution, which can be mitigated by hedgerows. This study was the first attempt in Brazil to investigate the efficiency of six different hedgerow species in reducing pesticide residues in air. A fluorescent compound (p-aminobenzoic acid or PABA) was introduced in the sprayed pesticide fluid that traced the pesticide in the water. Samples were collected in Petri dishes positioned on stakes at different heights in front of and behind the hedgerows. Data indicated barrier efficiency of up to 99%. Simulation of nontarget drift contamination with herbicide concentrations exhibited reduced senescence effects on leaves and posed no threat to survival. Hedgerows are feasible, simple, and inexpensive techniques, which may be used easily by farmers, independent of external support and efficiently mitigating indoor pesticide pollution, thus protecting human health. Integr Environ Assess Manag 2022;18:19-24. © 2021 SETAC.

Use of hedgerows by mammals in an intensive agricultural landscape

Agricultural intensification causes habitat modification, sometimes leading to habitat loss and subsequent loss of connectivity. Remaining species in these agriculture-dominated landscapes often use hedgerows, such as windbreaks or riparian strips, as movement corridors or even as habitats. However, the understanding of the use of these hedgerows by mammals is limited and could be improved with the use of high-resolution remote sensing data, which are unbiased, detailed and repeatable. The aim of this study was to assess the attributes that affect medium- and large-sized mammals’ use of hedgerows, with in situ and remotely sensed data (including LiDAR and multispectral images) in an agriculture-dominated landscape in southern Québec. Twenty-three hedgerows were selected and characterized with both field surveys and remote sensing analyses, like LiDAR metrics and vegetation indices. Wildlife frequentation of each hedgerow was measured using camera traps, from late spring to early fall in 2018. 431 mammal detections were obtained among all 23 hedgerows. From this, seven species were recorded, all of them opportunistic and well adapted to agricultural environment. Results showed significant differences in mammal use of hedgerows. Coefficients of the better-ranked models based on AICc indicated a positive relationship between hedgerow length and their use by mammals, and a negative relationship with the hedgerow width. Hedgerow use by mammals also increased as tree cover and understory density increased, and as human disturbance decreased. These results characterized for the first time the variables influencing hedgerow use by a broad set of medium- and large-sized mammal species and confirmed their use as movement corridors and/or habitat. This study also confirmed the complementary usefulness of variables derived from remote sensing combined with field data. The low explanatory power of variables often cited in the literature (e.g. NDVI, gappiness) also highlights the need to further explore their specific influence on mammals. The information provided by this study supports the beneficial role played by hedgerows for wildlife conservation in intensive agricultural landscapes. Management guidelines are provided as well as future research avenues.

The use of hedgerows as flight paths by moths in intensive farmland landscapes

Linear boundary features such as hedgerows are important habitats for invertebrates in agricultural landscapes. Such features can provide shelter, larval food plants and nectar resources. UK butterflies are known to rely on such features, however their use by moths is understudied. With moth species suffering from significant declines, research into their ecology is important. This research aimed to determine whether UK moth species are using hedgerows as flight paths in intensive farmland. The directional movements of moths were recorded along hedgerows at 1, 5 and 10 m from the hedgerow face. The majority of moths recorded within the study were observed at 1 m from the hedgerow (68 %), and of these individuals, 69 % were moving parallel in relation to the hedge. At further distances, the proportion of parallel movements was reduced. These results suggest that hedgerows may be providing sheltered corridors for flying insects in farmland landscapes, as well as likely providing food plants and nectar resources, emphasising the importance of resource-based approaches to conservation for Lepidoptera.

Use of hedgerows as a key element of badger (Meles meles) behaviour in Ireland

Human modification of landscapes is one of the greatest threats facing biodiversity worldwide and conversion of native habitat to agricultural land is widely perceived as contributing significantly to biodiversity declines. However, some species have proven to be adaptable to human-induced habitat change. Here, we show that over the course of the relatively short period of co-existence between badgers (Meles meles) and humans in Ireland, badgers have adapted to using the man-made field boundaries that have replaced native woodland. Our study population, which was located in an intensively managed agricultural landscape, predominantly located their setts and latrines in or alongside hedgerows. In addition, for the first time, we show that badgers selectively foraged along field boundaries, with this behaviour perhaps linked to a greater diversity of dietary items in hedgerows and the potential cover from perceived threats offered by dense undergrowth. This preferential use of man-made landscape features has implications for how we assess habitat use in this species and perhaps also for modelling studies of bovine tuberculosis transmission in agricultural landscapes.

Pest-removal services provided by birds on small organic farms in northern California

Many studies have established that birds may provide a pest removal service on farms, although few studies have taken place in temperate row crop agriculture. Wildlife-friendly agricultural practices such as organic farming and the use of hedgerows can in turn provide needed habitat for birds in developed landscapes. In this study, we examined how pest removal provided by birds varies within and between “wildlife-friendly” organic row-crop farms in northern California, USA. We used point counts to assess bird diversity on 29 small organic farms and simulated lepidopteran pest outbreaks on each farm using sentinel pest experiments. We measured how the probability of pest removal varied with local habitat characteristics within the farm, and with bird diversity parameters between farms. We also used exclosure experiments to determine whether birds provide a significant pest removal service in organic row-crop agriculture. In the sentinel pest experiments, birds depredated between 0 and 80% of caterpillar presentation stations within 7h, with a mean of 24% depredation per farm; the probability of pest removal was higher in areas close to uncultivated shrubby field margins (“hedgerows”). There was only weak evidence that the probability of pest removal was higher on farms with higher avian insectivore richness, and no evidence that pest removal varied with species diversity or abundance. Exclosure experiments on kale crops showed no significant effects of bird exclosure treatment on arthropod abundance or crop yield. However, natural caterpillar densities were relatively low during the exclosure experiment (approximately one caterpillar/m2). These results suggest that birds may be more helpful in responding to pest outbreaks than in controlling pests at non-irruptive densities on organic row crop farms in this study system. The prevention of pest outbreaks is an essential ecosystem service on any farm, and the rapid response of birds to pest outbreak conditions is an indicator of resiliency in the agroecosystem. Therefore, the retention of uncultivated shrubby field margins in this system may benefit both birds and farmers.

Landscape composition influences roe deer habitat selection at both home range and landscape scales

Understanding how patterns of habitat selection vary in relation to landscape structure is essential to predict ecological responses of species to global change and inform management. We investigated behavioural plasticity in habitat selection of roe deer (Capreolus capreolus) in relation to variable habitat availability across a heterogeneous agricultural landscape at the home range and landscape scales. As expected, woodland was heavily selected, but we found no functional response for this habitat, i.e. no shift in habitat selection with changing habitat availability, possibly due to the presence of hedgerows which were increasingly selected as woodlands were less abundant. Hedgerows may thus function as a substitutable habitat for woodlands by providing roe deer with similar resources. We observed a functional response in the use of hedgerows, implying some degree of landscape complementation between hedgerows and open habitats, which may in part compensate for lower woodland availability. We also expected selection for woodland to be highest at the wider spatial scale, especially when this habitat was limiting. However, our results did not support this hypothesis, but rather indicated a marked influence of habitat composition, as both the availability and distribution of resources conditioned habitat selection. There was no marked between-sex difference in the pattern of habitat selection at either scale or between seasons at the landscape scale, however, within the home range, selection did differ between seasons. We conclude that landscape structure has a marked impact on roe deer habitat selection in agricultural landscapes through processes such as landscape complementation and supplementation.

Dispersal of single‐ and double‐brood populations of the European earwig, Forficula auricularia: a mark‐recapture experiment

AbstractQuantitative information on dispersal of insects should be taken into consideration for making efficient pest management decisions. Such information was not available for the European earwig, Forficula auricularia L. (Dermaptera: Forficulidae), an important biocontrol agent in fruit orchards. A mark‐recapture experiment was carried out in Belgian orchards, where marked earwigs were released at a single point and recaptured after 1 month. Dispersal from this release point was analysed using an analytical formula of a simple diffusion model with disappearance (e.g., as a result of death) derived by Turchin & Thoeny (1993; Quantifying dispersal of southern pine beetles with mark‐recapture experiments and a diffusion model. Ecological Applications 3: 187). The cumulative number of recaptured earwigs as a function of the distance of release was used to fit the model and estimate parameters. A derived expression, in terms of these parameters, was used to estimate the frequency distribution of the population, as the radius of a circle enclosing various proportions of the earwigs’ dispersal distances. In Belgium, populations of the European earwig can have two life‐history strategies, single‐ (SBP) and double‐brood populations (DBP). Therefore, mark‐recapture experiments were carried out on both population types. We fitted data from SBP (n = 10) and DBP (n = 16) successfully in both the diffusion model and in an exponential curve. Because of the biological relevance, estimates of the diffusion model were used for calculating the frequency distributions. Males and females dispersed the same distances. No differences were found between orchards with different spatial structures (apple and pear). According to literature data, mobility of earwigs is very low compared with other arthropods, which has consequences for the efficiency of biocontrol interventions, like mass releases of earwigs or the use of hedgerows for the establishment of healthy (source) populations. Quantitative results revealed that earwigs of SBP dispersed four times further than earwigs of double‐brood populations. For instance, 95% of the population remained within a radius of 28.6 m in SBP and 7.54 m in DBP.

Conservation value of linear woody remnants for two forest carnivores in a Mediterranean agricultural landscape

Summary 1. The loss of biodiversity caused by agricultural expansion can be countered by adopting wildlife-friendly farming strategies and by expanding the network of nature reserves. The potential benefits of agricultural extensification, represented in Europe by agri-environmental schemes, still remain unclear. In particular, the effectiveness of preserving linear woody vegetation to retain forest carnivores in farmland has received limited attention. We document the value of hedgerows and narrow strips of riparian forest for the Egyptian mongoose Herpestes ichneumon and the common genet Genetta genetta. 2. In an agricultural mosaic of southern Spain containing 4·7% of woody vegetation, we tested hypotheses about the role of linear elements and three farmland types differing in the amount, quality and structure of woody cover. We analysed the influence of linear elements on the placement and utilization of home ranges by combining compositional analysis and numerical methods. 3. Mongooses and genets strongly selected linear woody vegetation. All types of farmland, including open fields, dehesa (savanna-like pastureland or arable land rich in oak trees Quercus ilex and Q. suber) and olive Olea europaea groves, were avoided, suggesting that both species strictly depend upon native woody cover. 4. Most individuals made regular use of hedgerows and some individuals used hedgerows as the only source of woody cover in their home ranges. 5. The distribution of home ranges suggested that individuals made up a continuous, rather than discrete, population in a spatially structured habitat. An evenly distributed hedgerow network across the intervening agricultural matrix could prevent population fragmentation. 6. Synthesis and applications. A suitable network of linear cover allows some forest carnivores to survive in agricultural landscapes containing a low proportion ( 0·5 km), width (4–10 m), quality (continuous native shrubs, scattered native trees, low levels of human disturbance), density (10–50 m ha−1) and a regular distribution of linear features are key elements in the conservation or restoration of agricultural landscapes where the preservation of small forest carnivores is an objective.

The Conservation Value of Hedgerows for Small Mammals in Prince Edward Island, Canada

The aim of this study was to investigate the use of hedgerows by small mammals in four agricultural landscapes in Prince Edward Island, Canada. The Island has one of the highest percentages of land (about 48%) devoted to crop production and pasture in all of Canada. Therefore, identifying the landscape elements that can mitigate the effects of habitat fragmentation resulting from agricultural practices is essential to preserve the biodiversity of Prince Edward Island. We quantified species richness, abundance and diversity of small mammals in 13 hedgerows and 13 attached forest patches. Although all the species detected in forest patches were also found in hedgerows, significant differences in species diversity and abundance suggest that not all species benefit equally from hedgerows. The abundance of small mammals other than the eastern chipmunk (Tamias striatus) increased in hedgerows longer than about 225–250 m, but was independent of hedgerow's length in hedgerows smaller than 225–250 m. Predators (Mustela erminea) were captured in hedgerows, but not in forest patches. Relationships between small mammal variables and hedgerow features (microhabitat, macrohabitat and landscape) suggested that most small mammal species would benefit from hedgerows having high shrub diversity, ground cover with vines and leaf litter, and few non-vegetated gaps. Removal of hedgerows, especially large ones, may affect long-term survival of some small mammal species inhabiting agricultural landscapes of Prince Edward Island.

Are hedgerows the route to increased farmland small mammal density? Use of hedgerows in British pastoral habitats

Linear habitats are becoming increasingly common as a consequence of habitat fragmentation, and may provide the sole habitat for some species. Hedgerows are linear features that can vary substantially in structure and quality. Having surveyed 180 hedgerows, in four locations, and sampled their small mammal communities we examined the effect of physical hedgerow attributes on the abundance of small mammal species. Using three elements of landscape structure, we explored whether variation was best explained by the Random Sample Hypothesis (that small islands represent a random sample of those species populating larger areas), or by the Fragmentation Hypothesis (that species abundance will decrease with a loss of habitat area). We tested the relationship between the relative abundance of small mammals and 1. hedgerow connectivity; 2. total habitat availability and 3. local habitat complexity. We then explored the predictive power of combinations of these habitat variables. Connectivity was a positive predictor of wood mice Apodemus sylvaticus, and hedgerow gappiness was a negative predictor of bank voles Clethrionomys glareolus. The total amount of habitat available (hedgerow width, height and length) was a positive indicator of total small mammal biomass. These results support the Fragmentation Hypothesis that species abundance and distribution decrease with a loss of habitat area. The preservation of linear and associated habitats may therefore be important in maintaining metapopulations of the species we studied.

Hedgerows as corridors for woodland plants: a test on the Po Plain, northern Italy

The use of hedgerows as corridors for forest vascular species has been widely studied, but only in humid oceanic and continental climates; no replicated trials have ever been performed on corridor function. Given these premises, a study was done on the eastern Po Plain, in a transition area between the Temperate (Eurosiberian) and Mediterranean climatic zones, adopting the same sample shape and dimensions as a North-American study [Corbit et al. (1999) J Ecol 87:220–232]. The following research questions were posed: (1) how common are forest species in hedgerows? (2) do origin, isolation, distance from source, width and adjacent land-use factors correlate with the frequency of forest species? (3) are hedgerows corridors for forest species? To address these, three functional types of hedgerows, identified by comparing old aerial-photos, were sampled: remnant attached (n = 12) and remnant isolated (n = 6) with respect to the nearest woodland and regenerated attached (n = 4). If wooded patches were a source for hedgerows, then regenerated hedgerows should be more similar to an adjacent woodland than an isolated remnant. A 900 m2 circular plot in woodlands and an adjacent 90-m transect along hedgerows were sampled for the presence and cover of all plant species, then 39 woodland taxa were selected. Significant differences between the three hedgerow types emerged in forest species richness, but not in cover. The forest species composition in both remnant and regenerated attached hedgerows showed a strong affinity with the adjacent stand, implying a dispersal process from woodland (source) to regenerated hedgerows (sink). A distance effect on forest species distribution clearly linked to a corridor function was found only in regenerated hedgerows, while in the remnant attached ones, even with a composition similar to that of the nearest woodland source, other additional factors cannot be ignored to explain the fine scale distribution of forest species. The cover of the most common ant-dispersed species showed a similar distance effect while vertebrate-dispersed ones did not show any significant trend with distance from woodlands. Habitat suitability for forest species was affected by width, especially in hedges wider than 12 m, but not by adjacent land use.

Bird use of three types of field margins in relation to intensive agriculture in Québec, Canada

Habitat structure and bird use of field margins were studied in intensive farmlands of southern Québec, Canada. The main objectives were: (1) to assess the value of field margins for conserving avian diversity in agricultural landscapes, (2) to document their potential as breeding habitats for bird species particularly those considered as nuisance for crops, and (3) to describe habitat variables that best explained bird use of field margins. Three types of field margins were distinguished: (a) natural hedgerows ( n=27) with well developed tree and shrub strata, (b) planted windbreaks ( n=17) mostly composed of coniferous trees and generally devoid of a well structured shrub stratum, and (c) herbaceous field margins ( n=17) with isolated shrubs. A total of 42 bird species were recorded. Bird use of hedgerows and windbreaks was similar, herbaceous field margins having fewer bird species and individuals than the other two types of field margin. Field margins did not contribute significantly as breeding habitats of bird species that may damage crops, but offered shelter to a broad range of species potentially useful for biological pest control. Bird use of field margins was mostly related to hedges’ structural complexity and dimension. Conserving natural hedgerows, minimising mechanical and chemical control of the vegetation in field margins, and planting a mix of deciduous and coniferous species in windbreaks represent efficient conservation strategies both from a wildlife and an agronomic point of view.