Effects Of Habitat Management Research Articles

Effect of habitat management on arthropod community in crab apple orchards (Malus sylvestris (L.) Mill.) in Indonesia

ABSTRACT Crab apple (Malus sylvestris (L.) Mill.) is native to Central Europe and successfully commercially grown in Indonesia. Management practices that increase biodiversity in agroecosystems are essential for mediating the negative impacts of intensive agriculture. This study aims to compare arthropod abundance and diversity between grass ground cover and Hydrangea intercropping in crab apple orchards and assess their impact on arthropod functional groups providing ecosystem services. In this study, arthropods were sampled using three types of traps, i.e. pitfall trap, yellow sticky trap, and pan trap. Arthropod specimens were identified by order and family, then categorised by their ecological role: detritivore, omnivore, herbivore, the natural enemy (predator and parasitoid), and pollinator. Our study collected 164 families belonging to the five examined functional groups. We found that the family composition of arthropods was significantly different between Hydrangea intercropping and grass ground cover in crab apple orchards. Grass ground cover supports the increase of herbivore and natural enemy populations and it’s related to enhancing biological control. In addition, Hydrangea intercropping increases pollinator species richness and contributes to pollination services. Pest management in crab apple orchards may benefit from a combination of grass ground cover to encourage natural enemies and Hydrangea intercropping to increase pollinators.

Effects of habitat management on rodent diversity, abundance, and virus infection dynamics.

As anthropogenic factors continue to degrade natural areas, habitat management is needed to restore and maintain biodiversity. However, the impacts of different habitat management regimes on ecosystems have largely focused on vegetation analyses, with limited evaluation of downstream effects on wildlife. We compared the effects of grassland management regimes (prescribed burning, cutting/haying, or no active management) on rodent communities and the viruses they hosted. Rodents were trapped in 13 existing grassland sites in Northwest Arkansas, USA during 2020 and 2021. Rodent blood samples were screened for antibodies against three common rodent-borne virus groups: orthohantaviruses, arenaviruses, and orthopoxviruses. We captured 616 rodents across 5953 trap nights. Burned and unmanaged sites had similarly high abundance and diversity, but burned sites had a higher proportion of grassland species than unmanaged sites; cut sites had the highest proportion of grassland species but the lowest rodent abundance and diversity. A total of 38 rodents were seropositive for one of the three virus groups (34 orthohantavirus, three arenavirus, and one orthopoxvirus). Thirty-six seropositive individuals were found in burned sites, and two orthohantavirus-seropositive individuals were found in cut sites. Cotton rats and prairie voles, two grassland species, accounted for 97% of the rodents seropositive for orthohantavirus. Our study indicates that prescribed burns lead to a diverse and abundant community of grassland rodent species compared with other management regimes; as keystone taxa, these results also have important implications for many other species in food webs. Higher prevalence of antibodies against rodent-borne viruses in burned prairies shows an unexpected consequence likely resulting from robust host population densities supported by the increased habitat quality of these sites. Ultimately, these results provide empirical evidence that can inform grassland restoration and ongoing management strategies.

Grazed wet meadows are sink habitats for the southern dunlin (Calidris alpina schinzii) due to nest trampling by cattle.

The effect of habitat management is commonly evaluated by measuring population growth, which does not distinguish changes in reproductive success from changes in survival or the effects of immigration or emigration. Management has rarely been evaluated considering complete life cycle of the target organisms, including also possible negative impacts from management. We evaluated the effectiveness of cattle grazing in the restoration of coastal meadows as a breeding habitat for small and medium‐sized ground‐nesting birds by examining the size and demography of a southern dunlin (Calidris alpina schinzii) breeding population. Using a stochastic renesting model that includes within‐season variation in breeding parameters, we evaluated the effect of grazing time and stocking rates on reproduction. The census data indicated that the population was stable when nest trampling was prevented, but detailed demographic models showed that the population on managed meadows was a sink that persisted by attracting immigrants. Even small reductions in reproductive success caused by trampling were detrimental to long‐term viability. We suggest that the best management strategy is to postpone grazing to after the 19th of June, which is about three weeks later than what is optimal from the farmer's point of view. The differing results from the two evaluation approaches warn against planning and evaluating management only based on census population size and highlight the need to consider target‐specific life history characteristics and demography. Even though grazing management is crucial for creating and maintaining suitable habitats, we found that it was insufficient in maintaining a viable population without additional measures that increase nest success. In the presently studied case and in populations with similar breeding cycles, impacts from nest trampling can be avoided by starting grazing when about 70% of the breeding season has past.

The effects of habitat management on the species, phylogenetic and functional diversity of bees are modifiedby the environmental context.

Anthropogenic landscape elements, such as roadsides, hedgerows, field edges, and power line clearings, can be managed to provide important habitats for wild bees. However, the effects of habitat improvement schemes in power line clearings on components of diversity are poorly studied. We conducted a large-scale experiment to test the effects of different management practices on the species, phylogenetic, and functional diversity of wild bees in power line clearings (n=19 sites across southeastern Norway) and explored whether any treatment effects were modified by the environmental context. At each site, we conducted the following treatments: (1) Cut: all trees cut and left to decay in the clearing; (2) Cut+Remove: all trees cut and removed from the plot; and (3) Uncut: uncleared. The site-specific environmental context (i.e., elevation and floral diversity) influenced the species, phylogenetic, and functional diversity within bee species assemblages. The largest number of species was found in the Cut+Remove treatment in plots with a high forb species richness, indicating that the outcome of management practices depends on the environmental context. Clearing of treatment plots with many forb species also appeared to alter the phylogenetic composition of bee species assemblages, that is, more closely related species were found in the Cut and the Cut+Remove plots than in the Uncut plots. Synthesis and applications: Our experimental simulation of management practices in power line clearings influenced the species, phylogenetic, and functional diversity of bee species assemblages. Frequent clearing and removal of the woody debris at low elevations with a high forb species richness can increase the value of power line clearings for solitary bees. It is therefore important for managers to consider the environmental context when designing habitat improvement schemes for solitary bees.

Eastern whip‐poor‐will breeding ecology in relation to habitat management in a pitch pine–scrub oak barren

ABSTRACTNumerous wildlife species are dependent on the creation and maintenance of early successional forests, yet little is known about the effects of habitat management on some threatened species. One such species is the eastern whip‐poor‐will (Antrostomus vociferous), a nocturnal bird of conservation concern. We examined the effects of heavy thinning, mowing, burning, and herbicide treatments on this species by conducting point counts and nest searches on a pitch pine–scrub oak (Pinus rigida–Quercus ilicifolia) barren in western Massachusetts, USA, between 2006 and 2013. Our point‐count data showed that the abundance of calling birds was greater in managed shrublands such as scrub oak barrens and heavily thinned pitch pine stands, compared to closed‐canopy pitch pine and deciduous forest. We found a high number of whip‐poor‐will nests (n = 26) and roosts (n = 59), which we located primarily within managed shrublands. We did not search for nests in closed‐canopy forests, and we were unable to determine the extent of their use of the forest edge for nesting. Nevertheless, birds selected nest sites under residual deciduous trees within the early successional forests; therefore, canopy cover appears to be important for nest placement at the nest‐patch spatial scale, but not necessarily at a broader scale. Nests were found in both dense and sparse understory vegetation; none were found in vegetation patches that were <2 years since treatment. Estimated nest survival was 63% through incubation (daily survival rate = 0.977,n = 21), consistent with other published studies of nightjars in the United States and Canada. Creating and maintaining open‐canopy early successional forests in pitch pine–scrub oak barrens, with the retention of some residual deciduous trees, should increase the amount of habitat suitable for courtship, roosting, and nesting by eastern whip‐poor‐wills. © 2016 The Wildlife Society.

Effects of habitat management can vary over time during the recovery of an endangered bird species

Time and financial constraints often force conservationists to make ad hoc management decisions without sufficient knowledge to predict their effects. In particular, the effects of management on reproduction and survival are rarely evaluated and habitat dynamics are rarely taken into account. We evaluated the effects of three different forms of habitat alteration on the endangered Pale-headed Brushfinch (Atlapetes pallidiceps) in Ecuador during the phases of population increase and stabilization. More specifically, we monitored the effect of a natural experiment with three approaches (clearing, grazing and burning) to preserve the semi-open habitat of this species on the reproductive success of 220 breeding events over seven years and on the survival of 73 adults over three consecutive years. Habitat alteration had contrasting effects on reproduction and survival. All approaches increased the number of fledged chicks per breeding event while the population stabilized, but not while it increased. However, vegetation burning reduced survival probability of adult individuals. In addition, survival was strongly correlated to the presence of water in the territories. Overall, we revealed that the negative effects of vegetation burning on survival overrode the positive effects on reproduction, and could—if implemented at a larger scale—destroy the conservation aim of increasing the population size. Importantly, we show that the effectiveness of management differs depending on the actual population trend. Our study therefore shows that the a posteriori evaluation of ad hoc vegetation control can constitute an integral part of adaptive management and thereby also of long-term conservation planning of endangered species.

Linking habitat complexity with predation of pests through molecular gut-content analyses

Improving the diversity of farm systems or landscapes can lead to more effective biological control by providing refuge and alternative resources for colonising natural enemies. Within an experimental cabbage agroecosystem, we examined the effects of habitat management (i.e. herbicide use and cover crops) on pest populations and predator community structure, and report one of the first studies on the trophic links in this system using molecular gut-content analysis. In response to herbicide and cover crop management treatments designed to create different levels of habitat diversity, we quantified the abundance of two pests, Plutella xylostella Linnaeus (Lepidoptera: Plutellidae) and Pieris rapae Linnaeus (Lepidoptera: Pieridae), and predators. We designed species-specific primers to detect prey DNA in predators' guts. Pieris rapae were significantly more abundant in plots where cover crops were killed early in the season, and habitat management generated unique predator communities in response to weed management treatments. Thirty-five per cent of predators tested positive for prey DNA, and habitat management had interactive effects on predation of P. xylostella. Combined we found that habitat management has variable effects on natural enemy–pest interactions.

The role of protected area wetlands in waterfowl habitat conservation: Implications for protected area network design

The principal goal of protected area networks is biodiversity preservation, but efficacy of such networks is directly linked to animal movement within and outside area boundaries. We examined wetland selection patterns of mallards (Anas platyrhynchos) during non-breeding periods from 2010 to 2012 to evaluate the utility of protected areas to migratory waterfowl in North America. We tracked 33 adult females using global positioning system (GPS) satellite transmitters and implemented a use-availability resource selection design to examine mallard use of wetlands under varying degrees of protection. Specifically, we examined effects of proximities to National Wildlife Refuges, private land, state wildlife management areas, Wetland Reserve Program easements (WRP), and waterfowl sanctuaries on mallard wetland selection. In addition, we included landscape-level variables that measured areas of sanctuary and WRP within the surrounding landscape of each used and available wetland. We developed 8 wetland selection models according to season (autumn migration, winter, spring migration), hunting season (present, absent), and time period (diurnal, nocturnal). Model averaged parameter estimates indicated wetland selection patterns varied across seasons and time periods, but ducks consistently selected wetlands with greater areas of sanctuary and WRP in the surrounding landscape. Consequently, WRP has the potential to supplement protected area networks in the midcontinent region. Additionally, seasonal variation in wetland selection patterns indicated considering the effects of habitat management and anthropogenic disturbances on migratory waterfowl during the non-breeding period is essential in designing protected area networks.

Improving Aquatic Warbler Population Assessments by Accounting for Imperfect Detection

Monitoring programs designed to assess changes in population size over time need to account for imperfect detection and provide estimates of precision around annual abundance estimates. Especially for species dependent on conservation management, robust monitoring is essential to evaluate the effectiveness of management. Many bird species of temperate grasslands depend on specific conservation management to maintain suitable breeding habitat. One such species is the Aquatic Warbler (Acrocephalus paludicola), which breeds in open fen mires in Central Europe. Aquatic Warbler populations have so far been assessed using a complete survey that aims to enumerate all singing males over a large area. Because this approach provides no estimate of precision and does not account for observation error, detecting moderate population changes is challenging. From 2011 to 2013 we trialled a new line transect sampling monitoring design in the Biebrza valley, Poland, to estimate abundance of singing male Aquatic Warblers. We surveyed Aquatic Warblers repeatedly along 50 randomly placed 1-km transects, and used binomial mixture models to estimate abundances per transect. The repeated line transect sampling required 150 observer days, and thus less effort than the traditional ‘full count’ approach (175 observer days). Aquatic Warbler abundance was highest at intermediate water levels, and detection probability varied between years and was influenced by vegetation height. A power analysis indicated that our line transect sampling design had a power of 68% to detect a 20% population change over 10 years, whereas raw count data had a 9% power to detect the same trend. Thus, by accounting for imperfect detection we increased the power to detect population changes. We recommend to adopt the repeated line transect sampling approach for monitoring Aquatic Warblers in Poland and in other important breeding areas to monitor changes in population size and the effects of habitat management.

Rapid response of a long-lived species to improved water and grazing management: The case of the European pond turtle (Emys orbicularis) in the Camargue, France

Among human activities, the effect of habitat management by grazing on population viability is ambiguous. Indeed, beneficial effects of grazing are expected by maintaining open meadows, but overgrazing is supposed to increase mortality by trampling. Grazing has been shown to negatively impact the survival of European pond turtle (Emys orbicularis) in the Camargue. Consequently, a new management plan was defined. We investigated the consequences of this management using capture–recapture methods to estimate variations of population sizes in this managed site and a control site over a 17 years period. Results show an increase of the number of adults and juveniles on the managed site after the management change. Our results suggest that improved water management with flooding in autumn provided better hibernation conditions, and that reduced grazing intensity in autumn/winter likely decreased the risk of trampling. Population size significantly increased in less than 4 years following the management change, probably by the relaxation of density-dependence. It is an original result for a long lived-species supposed to have an important time of resilience to perturbations.

Restoring Tropical Dry Forest Communities: Effects of Habitat Management and Outplantings on Composition and Structure

We sought to increase the conservation value and ecological resilience of a disturbed woodlot on protected land in suburban Miami‐Dade County, Florida, by restoring a local tropical dry forest community. These efforts included adding 26 “novel native” tropical hardwood hammock species in different SR and density treatments, and conducting regular habitat management actions including exotic biomass removal. We monitored a variety of community composition and forest structure variables over 2 years to assess the success of our restoration efforts and the relative roles of habitat management versus native outplantings in achieving those outcomes. Habitat management proved influential to changing forest structure, while both habitat management and outplantings impacted changes in community composition, at least in the short term. Habitat management and outplantings in combination, however, allowed us to successfully (1) increase the number of native species and decrease the number of exotic species, (2) increase the number of protected plant species on the site, and (3) alter the community composition and forest structure of the site from that of a highly disturbed woodlot to that of a typical Miami Rock Ridge tropical hardwood hammock. Our success in meeting these restoration goals in just 2 years is one such example where simple native outplanting and exotic control projects can produce large returns with minimal resources in the form of time, money, and manpower. Finally, restoring regrowth sites or other remnant habitats may prove an efficient and effective way to conserve biodiversity and basic ecosystem processes in close proximity to metropolitan areas.

Effectiveness of habitat management in the recovery of low-density populations of wild rabbit

Understanding the relationship between spatial patterns of landscape attributes and population presence and abundance is essential for understanding population processes as well as supporting management and conservation strategies. This study evaluates the influence of three factors: environment, habitat management, and season on the presence and abundance of the wild rabbit (Oryctolagus cuniculus), an important prey species for Mediterranean endangered predator species. To address this issue, we estimated wild rabbit presence and abundance by latrine counting in transects located in 45 plots within a 250 × 250 m grid from June 2007 until June 2009 in a 1,200 ha hunting area in southern Portugal. We then analyzed how wild rabbit presence and abundance correlate with the aforementioned factors. Our results showed that the main variable influencing wild rabbit presence and abundance was the distance to the artificial warrens. North and northeast slope directions were negatively related to wild rabbit presence. Conversely, rabbit presence was positively correlated with short distances to ecotone, artificial warrens, and spring. Regarding rabbit abundance, in addition to artificial warrens, soft soils, bushes, and season also had a positive effect. We found that environmental variables, management practices, and season each affect wild rabbit presence and abundance differently at a home range scale in low-density population. Thus, our major recommendations are reducing the distance to artificial warrens and ecotone, ideally to less than 100 m, and promoting habitat quality improvement on slopes with plenty of sun exposure.

Effectiveness of habitat management for improving grey partridge populations: a BACI experimental assessment

We assessed the impact of field division (4 m bare ground strips within wheat fields) and food supplementation (supplied through grain feeders) on grey partridge Perdix perdix L. populations using six–year ‘before–after’/’control–impact’ (BACI) experiments. We did not detect any convincing positive effects of either of these two schemes on partridge pair density and reproductive success. Increases in pair densities were similar on managed and control areas, and contrasting results were found between some sites. No consistent pattern was observed between reproductive success and feeding intensity. Our studies highlight the need for field experiments at farm–scale to test the effectiveness of management measures. We conclude that, in the context in which they are applied, management techniques directed towards increasing partridge density do not systematically provide the desired outcome. We develop our point of view about management in the Discussion.

Predator identification and effects of habitat management and fencing on depredation rates of simulated nests of an endangered population of Hermann’s tortoises

Nest predation has been identified as the main threat behind the negative population dynamics in chelonian species and in particular in the native Iberian population of the Western Hermann’s tortoise Testudo hermanni hermanni. This endangered subspecies is found within the Albera Nature Reserve, where this study was performed. We selected three formerly high-density tortoise areas to carry out different trials whose aims were to: (1) identify nest predator species, (2) test the success of reducing the shrub cover to reduce nest predation in potential new nesting areas, and (3) assess fencing efficiency to exclude predators. For the first objective, camera-trapping was used to identify nest predators, with sardines and artificial tortoise nests as lures. We obtained 825 pictures of possible predators and demonstrated that the beech marten was the most abundant predator in the study areas, followed by the badger and the wild boar. For the second objective, predation of artificial nests was compared between plots managed for shrub reduction (27 plots of 4, 25, and 100 m2) and a natural nesting area (nine control plots of 100 m2). Predation was strong in the managed plots (43.6% after 48 h and 99.6% after 144 h) but highest in the control area (100% after 48 h). Surprisingly, predation occurred at an even faster pace when we repeated the trial with a single artificial nest (in order to reduce odor intensity). Finally, we compared predation rates between eight fenced and eight unfenced plots of 100 m2. Fencing was partially effective to control nest predation because it excluded all the main predator species except the beech marten, which learned to go through it. Since the nest predation threat to this endangered population is critical, new strategies are needed to control nest predation by taking into account the ability of predators to learn nest location.

The effect of habitat management on home‐range size and survival of rural Norway rat populations

Summary Norway rat Rattus norvegicus populations are usually controlled with toxic baits, but this approach is increasingly recognized as having negative welfare and environmental impacts. An integrated strategy that relies less on rodenticides is therefore required. Here we investigate the possibility of using a resource‐based approach to rat population management. Structurally complex habitats provide rat populations with nest sites and opportunities to avoid predators; modifying habitats to reduce structural complexity might reduce their potential to support rat populations. As part of an integrated approach, this could be more sustainable than relying exclusively on lethal control. However, in order to target habitat management efforts most effectively with minimum impact on other species, an understanding of habitat utilization by Norway rats is required. In this study, rat populations on farms in the north‐east of England were monitored by radio‐tracking and population counts before and after a single phase of habitat modification. Rats living near farm buildings utilized areas with high levels of cover; habitat modification reduced the survival rate and size of these rat populations. Rats living in field margins also preferred areas with high levels of cover, but they had significantly bigger home ranges than rats living near farm buildings and were largely unaffected by small‐scale habitat management. Synthesis and applications. Our results indicate that habitat management near farm buildings has the potential to reduce the size of rat populations. As part of an integrated approach, this technique offers a way of reducing reliance on rodenticides. Habitat use by rats within the wider farm landscape suggests that land management practices have the potential to influence the size and distribution of rat populations; many game‐rearing practices and environmental policies designed to create habitats for ‘desirable’ farm wildlife, inadvertently create desirable habitats for rats.

Effects of habitat management on heathland response to atmospheric nitrogen deposition

A field experiment was carried out to investigate the impact of four different management treatments on the response of Calluna-dominated heathland to nitrogen additions of 0 or 30 kg ha −1 yr −1 at a lowland heath in Surrey, England. Post-management Calluna regeneration, growth and canopy development were significantly affected by both the form of management and by nitrogen addition. The effect of nitrogen on shoot growth was lower, in absolute terms, in those plots which had undergone more intensive management treatments. Seedling establishment was higher in plots which received a simulated accidental burn treatment, reflecting the greater proportion of bare ground and the high degree of physical disturbance associated with this treatment. Invasion by Deschampsia seedlings was increased by nitrogen addition, particularly in simulated accidental burn plots. In the long term, the need to maintain a low nutrient environment to favour Calluna dominance, particularly in the face of elevated nitrogen deposition, favours the use of managements which result in the export of a significant proportion of the organic nitrogen stores. However, further study is required to ensure that initial enhancement of seedling invasion by grass and other species, associated with these more intense managements, does not outweigh the long term benefits of associated nutrient removal.

Effects of habitat management on vegetation and above-ground nesting bees and wasps of orchard meadows in Central Europe

We studied the vegetation, stand structure and communities of above-ground nesting bees and wasps in 45 orchard meadows that were grazed, mown or abandoned (15 of each) in an agricultural landscape near Gottingen, Germany. Total species richness of plants was significantly lower and the proportion of dead wood was significantly higher on abandoned meadows compared to mown or grazed meadows. Species richness of bees, eumenid wasps and sphecid wasps did not differ between the three management types. Abundance of sphecid wasps was significantly higher on abandoned than on managed orchard meadows. Landscape context did not affect management type. The results suggest that management practises affect vegetation more significantly than the studied insect groups.

Torch-light transect surveys for moths

The use of light traps in sampling moth populations is an established technique used by entomologists and ecologists. However, trap data partly reflect the variable attractiveness of UV light to different species of moth. There are also potential problems of the practicality and expense of running traps in certain locations. An alternative method of recording moth populations is developed, using a modification of the transect count technique used for butterflies (Pollard and Yates, 1993) and recently applied to moths (Spalding, 1997). During transects, moths were observed by torch-light in a 5 by 5 m box, before the recorder walked on for 10 paces, and recorded moths in the next 5 m box. The transect approach was tested in the field, alongside traditional light trap and sugar methods. Transects recorded moth species for relatively little effort, produced repeatable measures of relative density, and provided habitat-specific data. This approach is likely to provide a valuable addition to light trapping in biodiversity inventories, species surveys, and in monitoring the effects of habitat management for conservation.

The Ecology and Conservation of the Heath Fritillary Butterfly, Mellicta athalia. III. Population Dynamics and the Effect of Habitat Management

The Ecology and Conservation of the Heath Fritillary Butterfly, Mellicta athalia. III. Population Dynamics and the Effect of Habitat Management

Using Pheasant Band Recoveries to Evaluate Habitat on Shooting Preserves

Band recoveries from 4,376 pheasants ( Phasianus colchicus ), banded and released over three hunting seasons on a put-and-take shooting preserve, were used to test the effectiveness of habitat management designed to increase harvest rates on seven hunting units. Recoveries were lowest where annual plantings failed to yield adequate food and cover because of low soil fertility, where perennial cover was sparse or deteriorating, or where cover bordering the hunting unit was adequate to attract and hold birds. Recoveries were highest where good soil fertility and adequate perennial plantings existed and were maintained regularly by management practices. Abstract: Band recoveries from 4,376 pheasants ( Phasianus colchicus ), banded and released over three hunting seasons on a put-and-take shooting preserve, were used to test the effectiveness of habitat management designed to increase harvest rates on seven hunting units. Recoveries were lowest where annual plantings failed to yield adequate food and cover because of low soil fertility, where perennial cover was sparse or deteriorating, or where cover bordering the hunting unit was adequate to attract and hold birds. Recoveries were highest where good soil fertility and adequate perennial plantings existed and were maintained regularly by management practices.