Litter Depth Research Articles

Leaf litter and irrigation can increase seed germination and early seedling survival of the recalcitrant‐seeded tree Beilschmiedia miersii

AbstractAlthough regeneration of recalcitrant‐seeded tree species can be affected by prolonged drought, especially in Mediterranean regions, little is known about the response of such species to varying site conditions. A field experiment was performed to determine the effect of irrigation and leaf litter cover on seed germination and early seedling survival of the vulnerable recalcitrant‐seeded tree Beilschmiedia miersii (Lauraceae). Two levels of irrigation (non‐irrigated and irrigated units) and three levels of leaf litter depth (0, 5 and 12 cm) were applied to 72 groups of 30 seeds along a wet ravine of the Coastal Range of Central Chile, equally distributed across sites with different levels of canopy cover. Seed germination was significantly increased by irrigation only under closed‐canopy cover, and by leaf litter cover (>5 cm) under all canopy conditions. The effect of leaf litter on germination increased with canopy openness, while the effect of irrigation did not show any tendency. Meanwhile, early seedling survival was significantly increased by irrigation under intermediate canopy cover, and by leaf litter (>5 cm) under closed‐canopy cover. As a result of its overall positive effect on germination, leaf litter should be maintained within B. miersii communities, particularly under intermediate to closed‐canopy conditions, where it can also increase early seedling survival, and both seed germination and early seedling survival might be increased through additional water inputs. The presence of leaf litter might help retaining such inputs, prolonging their effect on regeneration of B. miersii communities. We see this as a baseline assessment of regeneration and persistence that needs further testing on species with similar traits, given the expected increase in the frequency and length of dry periods into the future.

The 15-year post-treatment response of a mixed-conifer understory plant community to thinning and burning treatments

Disturbance is central to maintaining diversity in forest ecosystems. In the dry forests of the western United States, over a century of fire exclusion has altered the fire regimes of these forests, resulting in high fuel loads and a loss of plant diversity. Mechanical thinning and prescribed fire are widely used to restore structural complexity and species diversity in many western U.S. forests. While studies have shown that the reintroduction of fire into these forests initially promotes plant diversity, there is limited information on the persistence of this effect. We evaluated the effects of thinning and burning treatments on the understory plant community fifteen years after treatment in an old-growth, Sierran mixed-conifer forest. Using a full-factorial design, including three levels of thinning and two levels of burning, we found mechanical thinning and prescribed fire reduced litter depths and increased the availability of bare ground, resulting in an initial increase in herb cover. However, fifteen years after treatment, litter depths and shrub cover increased, resulting in a more homogenous understory community and a loss of herb cover. Overall, our results suggest that while thinning and burning treatments initially promote herbaceous plant cover, these effects are short lived in the absence of a second disturbance.

Contributions of throughfall, forest and soil characteristics to near-surface soil water-content variability at the plot scale in a mountainous Mediterranean area

Soil water-content (SWC) variability in forest ecosystems is affected by complex interactions between climate, topography, forest structure and soil factors. However, detailed studies taking into account the combined effects of these factors are scarce. This study's main aims were to examine the control that throughfall exerts on local spatial variation of near-surface soil water-content and to combine this information with forest structure and soil characteristics, in order to analyze all their effects together. Two stands located in the Vallcebre Research Catchments (NE Spain) were studied: one dominated by Quercus pubescens and the other by Pinus sylvestris. Throughfall and the related shallow SWC were monitored in each plot in 20 selected locations. The main characteristics of the nearest tree and soil parameters were also measured. The results indicated that mean SWC increment at the rainfall event scale showed a strong linear relationship with mean throughfall amount in both forest plots. The % of locations with SWC increments increased in a similar way to throughfall amount in both forest plots. The analyses considering all the effects together indicated again that throughfall had a significant positive effect in both forest plots, while soil litter depth showed a significant negative effect for the oak plot but lower statistical significance for the pine plot, showing a comparable –although more erratic– influence of the organic forest floor for this plot. These results, together with lower responses of SWC to throughfall than expected in rainfall events characterized by low preceding soil water-condition and high rainfall intensity, suggest that litter layer is playing an important role in controlling the soil water-content dynamics. The biometric characteristics of the nearest trees showed significant but very weak relationships with soil water-content increment, suggesting that stemflow and throughfall may act at lower distances from tree trunk than those presented in our study.

Characterizing Forest Floor Fuels Surrounding Large Sugar Pine (Pinus lambertiana) in the Klamath Mountains, California

Fire exclusion has contributed to substantial basal accumulations of forest floor fuels in many historically fire-prone forests in western North America. These accumulations can contribute to undesired impacts (e.g., elevated tree mortality, more smoke production). Thus, managers interested in limiting some of these impacts require a better understanding of the spatial factors contributing to forest floor fuel variation in long-unburned forests. To address this need, we measured the forest floor mound size and depth of each layer at four distances from the tree (base, half, edge, and beyond) in each cardinal direction from the tree, and a subset of density measures for each layer and position around 25 large sugar pine (Pinus lambertiana) in the Klamath Mountains of California. Based on our study we found: 1) duff depths were greater than litter depths and both decreased with distance from tree; 2) duff densities were typically greater than litter but were highly variable with distance to tree; 3) litter and duff depths were positively correlated with loading; 4) use of a previously developed depth-to-loading equation performed well, but tended to underestimate litter loading and overestimate duff loading; and 5) tree size was the most strongly related to basal accumulations of forest floor fuels. Our results indicate there are consistent tree characteristics that can help predict the accumulation of forest floor fuels. This research can help provide managers with site-specific equations to inform fuel and fire treatments in areas with substantial basal accumulation in forests with large sugar pine.

Animal- and management-based welfare indicators for a conventional broiler strain in 2 barn types (Louisiana barn and closed barn).

The aim of this observational study was to describe health- and management-related welfare indicators for a conventional broiler strain housed in 2 barn types (Louisiana barn and closed barn) on the same farm and to assess the impact of age and housing conditions on these indicators. Broilers were examined 4 times in each of 7 fattening periods. Their weight gain, gait score, and further animal-based indicators did not differ between the barn types. On average 46% showed no sign, 51% a minor but visible, and 3% a profound lameness at the end of the fattening period (fattening day 39). Soiling of the plumage, skin scratches, foot pad dermatitis, and hock burns worsened with increasing age. Soiling of the plumage was correlated negatively with litter depth (Pearson, r = -0.549, P = 0.042) and positively with litter quality (Pearson, r = 0.641, P = 0.013). Skin scratches occurred in 89% of the broilers (32% deep with penetration of dermis) on fattening day 39 and were correlated positively with cumulative mortality (Pearson, r = 0.615, P = 0.019), indicating a severe animal welfare impact. Foot pad dermatitis did not correlate with health- or management-related indicators, whereas hock burn correlated positively with the broilers' weight (Pearson, r = 0.853, P < 0.001) and with ammonia concentrations (Pearson, r = 0.577, P = 0.031). Management-related indicators (antibiotic treatments, dead on arrival) and cumulative mortality did not differ between the barn types. At the end of the fattening period, the litter quality was worse and concentrations of ammonia and peaks of high carbon dioxide concentrations were higher in the Louisiana than in the closed barn. The light intensity was on average 20 times higher in the Louisiana than in the closed barn without any negative impact. Summarizing, the barn type did not seem to influence the investigated welfare indicators, but Louisiana barns might need a more precise management to maintain the required ranges of noxious gases and litter quality.

Effects of land use legacies and habitat fragmentation on salamander abundance

Landscape modification is an important driver of biodiversity declines, yet we lack insight into how ongoing landscape change and legacies of historical land use together shape biodiversity. We examined how a history of agricultural land use and current forest fragmentation influence the abundance of red-backed salamanders (Plethodon cinereus). We hypothesized that historical agriculture and fragmentation cause changes in habitat quality and landscape structure that limit abundance. We measured salamander abundance at 95 forested sites in New York, USA, and we determined whether sites were agricultural fields within the last five decades. We used a structural equation model to estimate relationships between historical agriculture and salamander abundance mediated by changes in forest vegetation, microclimate, and landscape structure. Historical agriculture affected salamander abundance by altering forest vegetation at a local scale and forest cover at a landscape scale. Abundance was lowest at post-agricultural sites with low woody vegetation, leaf litter depth, and canopy cover. Post-agricultural sites had limited forest cover in the surrounding landscape historically, and salamander abundance was positively related to historical forest cover, suggesting that connectivity to source populations affects colonization of regenerating forests. Abundance was also negatively related to current forest fragmentation. Historical land use can have legacy effects on animal abundance on par with effects of ongoing landscape change. We showed that associations between animal abundance and historical land use can be driven by altered site conditions and surrounding habitat area, indicating that restoration efforts should consider local site conditions and landscape context.

The Effects of Litter Layer and Topsoil on Surface Runoff during Simulated Rainfall in Guizhou Province, China: A Plot Scale Case Study

Litter layers and topsoil have important effects on surface runoff. To investigate these effects at the plot scale, artificial rainfall experiments were conducted on micro-runoff plots in Guizhou Province, China. Three types of plots were selected, the thin litter layer with low soil bulk density type (T-L type), the thick litter layer with high soil bulk density type (T-H type), and the moderate litter depth and soil bulk density type (M type), and three artificial rainfall intensities (30 mm/h, 70 mm/h, 120 mm/h) were used. The runoff volume was largest in the T-H type plot at different rainfall intensities and durations. Runoff in the M type plot had characteristics of both the T-L and T-H type plots. The runoff yielding speed was significantly higher and the runoff yielding time was significantly lower in the T-H type plot. In general, the runoff coefficient was the smallest in the T-L type plot and largest in the T-H type plot. The variations in the runoff coefficient were 15.6%, 19.3%, and 5.8% for the T-L, T-H, and M type plots respectively. The results of this study can improve the understanding of surface runoff processes at the plot scale under different litter and surface soil conditions.

Natural regeneration of Pinus brutia Ten. in a recreational public forest in Zawita-Kurdistan region, Iraq

Zawita natural forest has recently has been subject to mass recreational activities during spring that have denuded large areas of the forest. It was thus essential to assess regeneration before designing optimizing strategies. To this end, we studied the overstory canopy and microhabitat conditions for recruitment of Pinus brutia Ten in 10 plots (20 × 25 m) on the southern aspects where the Zawita natural forest is still present. In total, 1540 regenerating P. brutia were recorded, 854 seedlings, 597 saplings, and 89 trees. Seedlings and saplings were more frequent beyond the canopy than under the canopy of the parent trees. Regeneration requirements differed between seedlings and saplings. The probability of the occurrence of seedlings was negatively correlated with increasing litter depth and increasing soil compaction. The density of saplings only showed a positive significant correlation with increasing slope. The nearest neighbor index showed a trend toward a positive spatial association between understory shrubs with their neighboring seedlings at a mean distance of 1.6 m. Overall, the study highlighted the requirements for seedling regeneration as a relatively open canopy cover, a light understory litter layer, and non-compacted soils. These results are a step towards designing effective management and restoration programs.

The role of plant functional traits in understanding forest recovery in wet tropical secondary forests

Simultaneous measurement of plant functional traits and the regeneration environment should shed light on the plant-environment interactions and feedbacks as secondary forest regenerates. However, little of such work has been done in the wet tropics, and even fewer studies have examined soil nutrients. We investigated whether plant functional traits and environmental variables explain the varied recovery of secondary forests in Singapore. Our study plots included three primary forest plots and eight approximately 60-year-old secondary forest plots regenerating from intensive agricultural activities. Using 35 seedling quadrats, we asked: Q1) How do environmental variables explain the variation in seedling functional traits observed in primary and secondary forests? Q2) How do seedling traits, adult traits and environmental variables relate and explain variation in species richness and stem density in secondary forests? We found that both light and soil fertility explained the shifts in plants functional traits from poorly recovering secondary forests to primary forests. Poor forest regrowth was correlated with high soil aluminum levels and lower leaf nitrogen concentrations. Low nutrients and high aluminum saturation were also negatively correlated with seedling species richness, but not stem density, in the secondary forests. Forest recovery is probably slowed by positive feedback between slower nutrient returns from slow decaying litter and further recruitment of nutrient conserving species, as indicated by positive correlations among adult leaf CN ratio, litter depth, soil CN ratio and quadrat level CN ratio. Plant functional traits are indicative of the strategies of successful seedlings and do not necessarily relate to overall forest recovery. Hence, while some specialist plant species are able to accrue high nutrients on degraded soils with aluminum toxicity and low nutrients, species richness on these soils was poor. This underscores the need to concurrently measure environmental variables and plant traits when investigating the mechanisms driving changes during forest recovery.

Distinct edge effects and reproductive periods of sympatric litter-dwelling scorpions (Arachnida: Scorpiones) in a Brazilian Atlantic forest

Edge effects have drastically affected species living in tropical forests. However, understanding how species respond to edge effects remains a challenge, owing to the many factors involved and different responses of each species thereto. Here, we analyzed how the abundance of two sympatric scorpion species (Tityus pusillus and Ananteris mauryi) and their potential prey varied as a function of microhabitat changes (litter depth, dry mass, and leaf shape) from edge to interior forest habitats. We further analyzed the contribution of potential prey to scorpion abundance and reproductive periods. Data were collected monthly at three 300-m² transects/site at distances of 10, 100, and 200m from the forest edge in a fragment of the Atlantic forest in northeastern Brazil, between April 2016 and March 2017. Scorpions responded differentially to edge effects, with A. mauryi abundance being similar along the edge-interior gradient, whereas T. pusillus had a higher abundance in the interior. As T. pusillus inhabit the top layer of the leaf litter, this species will possibly be more influenced by edge effects. In contrast, being a humicolous scorpion and inhabiting the bottom layers of leaf litter, A. mauryi would not be influenced by edge effects as much as T. pusillus. The reproductive period also was distinct between the two species, with T. pusillus reproducing in the dry season and A. mauryi in the rainy season. The oscillation in the abundance of different groups of prey at different periods maintained the overall prey abundance at a relatively constant level throughout the year, mitigating the effects of prey availability on the abundance and reproductive period of the scorpions. These results suggest that microhabitat exploitation is a key factor to sustain litter-dwelling scorpions in disturbed forest remnants and that T. pusillus can be an ecological indicator of edge effects.

Leaf Litter and Arboreal Ants (Hymenoptera: Formicidae) in a Mid-Atlantic Forest

The majority of ant diversity studies have been conducted in the tropics, but the number of studies conducted in temperate regions, like the US, is on the rise. Our research measured the richness and diversity of ants (Hymenoptera: Formicidae) in a coastal, temperate forest of Maryland. We collected leaf litter along twenty-four 100-m transects during May, July, and September of 2015 and measured litter depth and mass to determine if there was a relationship with ant abundance (density). We used Berlese funnels to collect 14 ant species (4208 individuals; n = 144 samples). Neither leaf-litter depth nor mass had an impact on ant abundance or species richness. We used aspirators and hand-collection methods to examine arboreal-ant foraging preference on deciduous and coniferous trees. Total species richness for both tree types was 21; we collected 19 species from deciduous trees and 17 from coniferous trees. Four species detected on deciduous trees were not present on conifers, and 2 species from conifers were not observed on deciduous trees. We observed higher abundances on deciduous trees (P = 0.016) and detected a preference for larger trees. We provide suggestions for conservation efforts for the coastal forests of Maryland, and our study contributes to the growing species inventory of ants on Maryland's eastern shore.

Recovery of ectomycorrhizal fungus communities fifteen years after fuels reduction treatments in ponderosa pine forests of the Blue Mountains, Oregon

Managers use restorative fire and thinning for ecological benefits and to convert fuel-heavy forests to fuel-lean landscapes that lessen the threat of stand-replacing wildfire. In this study, we evaluated the long-term impact of thinning and prescribed fire on soil biochemistry and the mycorrhizal fungi associated with ponderosa pine (Pinus ponderosa). Study sites were located in the Blue Mountains of northeastern Oregon where prescribed fire treatments implemented in 1998 and thinning treatments in 2000 included prescribed fire, mechanical thinning of forested areas, a combination of thinning followed by fire, and an untreated control. Soil sampling for this study occurred in 2014 and included four replications of each treatment for a total of 16 experimental units. Differences among treatments in Bray-P, total C and N, and pH were likely driven by the thinning treatments and the resultant deposition of residual slash following harvesting or the consumption of slash by prescribed fire. Similar litter depths across treatments suggest that litter depth stabilizes over time in these forests. After more than a decade of recovery, mycorrhizal fungi in dry inland forests dominated by ponderosa pine that were subjected to fire returned to levels similar to the untreated controls. The results of this study demonstrate the resiliency of these forests to disturbances associated with restoration treatments, providing managers increased flexibility if maintaining abundant and persistent fungal communities for healthy soils is an objective.

Influence of the herbaceous layer and litter depth on the spatial distribution of litter macrofauna in a forest plantation

The litter invertebrate community consists of species from different size, trophic and taxonomic groups. The distribution of the animal population of the litter horizon depends upon many factors, especially the content of the phytocoenosis, the projective herbaceous plant cover, moisture, litter thickness and the soil texture. This article analyses the variability of the main characteristics of litter invertebrate communities (total number, number of species, diversity according to the Shannon–Wiener and Pielou indices) on plots with different herbaceous plant composition and cover in plantations of Robinia pseudoacacia L. in the South steppe zone of Ukraine (territory of the “Tiligulsky” Regional Landscape Park). The taxonomic structure of the litter communities in the Robinia plantation was dominated by predatory groups of invertebrates (Carabidae, Aranea, Formicidae). The abundance of Julidae, Isopoda, Silphidae and Staphylinidae was relatively low. The studied forest plots were characterized by the simplified size structure of the litter macrofauna. The absence of species with body length of 16–20 mm and length over 20 mm indicates damage to the most significant trophic chains. The forest belt studied is in a highly disturbed condition, the plots being dominated by steppe species of herbaceous plants. The analyzed factors (diversity and extent of cover of herbaceous plants) do not determine the structure of the litter macrofauna community but affect it indirectly: a slight increase in the total number of invertebrates was observed in areas with minimal and maximum number of species of herbaceous plants. The relationship between the abundance of invertebrates and the percentage of herbaceous plant cover is manifested insignificantly. We noted a tendency for the number of invertebrate species to decrease along the gradient of herbaceous plant cover due to the concentration of dominant predatory species which exterminate other trophic groups of macrofauna.

Multi-Scale Clustering of Lyme Disease Risk at the Expanding Leading Edge of the Range of Ixodes scapularis in Canada

Since its detection in Canada in the early 1990s, Ixodes scapularis, the primary tick vector of Lyme disease in eastern North America, has continued to expand northward. Estimates of the tick’s broad-scale distribution are useful for tracking the extent of the Lyme disease risk zone; however, tick distribution may vary widely within this zone. Here, we investigated I. scapularis nymph distribution at three spatial scales across the Lyme disease emergence zone in southern Quebec, Canada. We collected ticks and compared the nymph densities among different woodlands and different plots and transects within the same woodland. Hot spot analysis highlighted significant nymph clustering at each spatial scale. In regression models, nymph abundance was associated with litter depth, humidity, and elevation, which contribute to a suitable habitat for ticks, but also with the distance from the trail and the type of trail, which could be linked to host distribution and human disturbance. Accounting for this heterogeneous nymph distribution at a fine spatial scale could help improve Lyme disease management strategies but also help people to understand the risk variation around them and to adopt appropriate behaviors, such as staying on the trail in infested parks to limit their exposure to the vector and associated pathogens.

Assessment of woodland grazing in southwest wisconsin

Grazing of farm woodlots in the upper Midwest is generally thought to degrade timber value and damage soil health. Nonetheless, Wisconsin property tax law creates an incentive for this practice. Therefore, this project sought to determine the effects of cattle grazing on vegetation and soil conditions in woodlands under different grazing management. We compared eleven grazed woodlots under various livestock management regimes with five woodlots that have not been grazed for at least 30 years in the Kickapoo Watershed in Crawford County, WI. We conducted vegetation surveys in all the woodlands and measured soil properties in a subset. We talked to farmers about their cattle management practices and beliefs about farm woodlots. Grazed woodlands had higher frequencies of introduced shrubs, less litter depth, fewer seedlings and saplings, more grass cover, and higher soil bulk density compared with un-grazed woodlands. Grazing negatively impacted regeneration and condition of seedlings, saplings, and saplings of commercial value. In grazed woods, we noted a relation between the cattle stocking rate and edaphic variables including amount of bare soil, litter depth, and canopy cover, and a difference between dairy and beef cattle in shrub density. We validated a set of simple indicators and metrics for on-going comparison of grazed and un-grazed farm woodlots in this area. Introduced shrub species was the clearest indicator of change, followed by litter depth, regeneration status of trees, and soil bulk density. The study points to potential opportunities for silvopasture techniques that could mitigate vegetation and soil degradation such as careful management of livestock stocking rate and timing of grazing.

The negative effect of wood ant presence on tick abundance

BackgroundTicks and tick-borne pathogens are a global problem for the health of humans and their livestock. Wood ants are important ecosystem engineers in forests worldwide. Although both taxa are well studied, little is known about their interactions under natural conditions. The purpose of the present field study was to test whether European red wood ants (Formica polyctena) influence the abundance of Ixodes tick populations in temperate forests.MethodsData collection took place in 130 sampling plots located at 26 ant nest sites paired with 26 control sites in northwestern Switzerland. At each sampling plot, tick abundance, ant abundance, ant nest volume and habitat variables (describing litter, vegetation and microclimate) were measured. We used linear mixed-effect models to analyze the abundance of questing ticks as a function of ant abundance and habitat variables.ResultsAnt nest volume, rather than the presence of ants, had a significant negative effect on tick abundance. The number of ticks decreased from 11.2 to 3.5 per 100 m2 if the volume of the adjacent ant nest increased from 0.1 m3 to 0.5 m3. Additionally, high vegetation cover and litter depth had negative and positive relationships with tick abundance, respectively.ConclusionsWe showed that the number of questing ticks was negatively correlated with the size of red wood ant nests. Further studies are needed to identify the mechanisms that drive the relationship. Possible mechanisms include the repellent effect of ant formic acid, and the predatory behavior of wood ants. The present field study suggests that red wood ants provide a new ecosystem service by reducing the local abundance of Ixodes ticks.

Litter-dwelling Ground Beetles (Coleoptera: Carabidae) and Ground Spiders (Araneae: Gnaphosidae) of the Ozark Highlands, USA

Each year, temperate deciduous forests produce a layer of litter comprised primarily of leaves. Two common and diverse taxa found in the litter layer are ground beetles (Coleoptera: Carabidae) and ground spiders (Araneae: Gnaphosidae). We collected and identified these groups on a monthly basis from April 2014 to March 2015 at 4 sites in Northwest Arkansas to determine their abundance and diversity across the following 3 variables: season, litter depth, and site location. A total of 480 litter samples and 208 pitfall-trap samples were collected and processed. These samples resulted in 645 carabids representing 47 species and 421 gnaphosids representing 15 species. Statistical analyses detected significant differences in species richness, average number of individuals, and species diversity of gnaphosids among sites. In contrast, leaf-litter depth had no significant effect on the number of individuals collected, species richness (except at one site), or species diversity of carabids and gnaphosids. Both carabids and gnaphosids were most abundant and diverse during the spring.

Defining functional groups and their vulnerability to the edge effect in a peri-urban forest in Mexico City

SUMMARYThe expansion of human settlements and primary-sector activities (agriculture and forestry) has resulted in the fragmentation of forests, but the impacts of this are still poorly understood. We examined the effect of patch size on the presence of plant functional groups along an edge–interior gradient. Plant species were classified based on a two-way indicator species analysis in order to determine their establishment thresholds and vulnerability along the gradient, while detrended correspondence analyses and canonical correspondence analyses were performed to identify environmental gradients related to vegetation distribution. Two groups of plant species were recognized in all patch sizes: one commonly found towards the edge and the other in the interior zone. The incidence of these groups was correlated with environmental factors associated with the edge–interior gradient, mainly with humidity, soil moisture and light (canopy opening and global site factor) in the edge zone and with litter cover, depth of litter, slope and soil and air temperature in the interior zone. Identifying the species’ threshold responses to fragmentation is key, as they provide tools to prevent the potential local extinction of species.

Boundaries in ground beetle (Coleoptera: Carabidae) and environmental variables at the edges of forest patches with residential developments.

BackgroundFew studies of edge effects on wildlife objectively identify habitat edges or explore non-linear responses. In this paper, we build on ground beetle (Coleoptera: Carabidae) research that has begun to address these domains by using triangulation wombling to identify boundaries in beetle community structure and composition at the edges of forest patches with residential developments. We hypothesized that edges are characterized by boundaries in environmental variables that correspond to marked discontinuities in vegetation structure between maintained yards and forest. We expected environmental boundaries to be associated with beetle boundaries.MethodsWe collected beetles and measured environmental variables in 200 m by 200 m sampling grids centered at the edges of three forest patches, each with a rural, suburban, or urban context, in Charlotte, North Carolina, USA. We identified boundaries within each grid at two spatial scales and tested their significance and overlap using boundary statistics and overlap statistics, respectively. We complemented boundary delineation with k-means clustering.ResultsBoundaries in environmental variables, such as temperature, grass cover, and leaf litter depth, occurred at or near the edges of all three sites, in many cases at both scales. The beetle variables that exhibited the most pronounced boundary structure in relation to edges were total species evenness, generalist abundance, generalist richness, generalist evenness, and Agonum punctiforme abundance. Environmental and beetle boundaries also occurred within forest patches and residential developments, indicating substantial localized spatial variation on either side of edges. Boundaries in beetle and environmental variables that displayed boundary structure at edges significantly overlapped, as did boundaries on either side of edges. The comparison of boundaries and clusters revealed that boundaries formed parts of the borders of patches of similar beetle or environmental condition.DiscussionWe show that edge effects on ground beetle community structure and composition and environmental variation at the intersection of forest patches and residential developments can be described by boundaries and that these boundaries overlap in space. However, our results also highlight the complexity of edge effects in our system: environmental boundaries were located at or near edges whereas beetle boundaries related to edges could be spatially disjunct from them; boundaries incompletely delineated edges such that only parts of edges were well-described by sharp transitions in beetle and/or environmental variables; and the occurrence of boundaries related to edges was apparently influenced by individual property management practices, site-specific characteristics such as development geometry, and spatial scale.

Evaluation of Management Practices in Layer Chickens and their Influence on Welfare Status in Kabete Sub-County, Kenya

Reduced land sizes, increased demand for food and employment creation are drivers for increased intensive poultry production in Kenya. Intensification of production is likely to compromise the welfare of birds raised for egg production (layers). There is therefore need to determine the welfare status of layers in smallholder farms in Kenya. This study was conducted in Kabete Sub-county of Kiambu County in Kenya, covering Muguga, Nyathuna and Kabete wards. Data was collected from 135 randomly selected farms comprising of 54, 55, and 26 from Muguga, Nyathuna and Kabete, respectively. One laying flock in each household was studied. A semi-structured questionnaire was used to collect data on feeding, housing, health and behaviour of layers. Measurements were taken to determine stocking densities, feeding, watering, perching and nesting spaces, house temperature and litter depth. Observations were made to assess house ammonia levels, litter quality and foot pad dermatitis. In each ward a focus group discussion with farmers was held. Focus group discussion was also held with extension agents. Hen-day egg production was the same (p&gt;0.05) in the three wards, with a mean of 80±12%. Water and feed were provided throughout the day by 100 and 80% of the farmers, respectively. The mean feed consumption was 115.2±15.7 g/bird/day, which was the same (p&gt;0.05) in the three wards. The mean feeding space was 10.4±3.0 cm/bird while the linear watering space was 2.5±0.7 cm/bird. Similar stocking densities (p &gt; 0.05) of 10±3, 10±3 and 11±3 birds/m2 were found in Muguga, Nyathuna and Kabete, respectively. Similar poultry house temperatures (p&gt;0.05) of 24.6±2.3, 24.4±2.2 and 22.9±2.9oC were recorded in Muguga, Nyathuna and Kabete, respectively. Ammonia level was not a problem in 64% of the houses studied. In 70% of the layer houses the litter moisture content was acceptable (dry). A small proportion of farmers (24%) provided perches for the layers. Similar perching space (p&gt;0.05) of 7.1±5.8, 12±11, 12±8.7 cm/bird was recorded in Muguga, Nyathuna and Kabete, respectively. About 37% of the farmers reported occurrence of diseases such as New Castle, gumboro, fowl pox and fowl typhoid. All farmers provided laying nests, but none of them provided sand bathing facilities. For control of cannibalism, 63% of the farmers provided fresh green vegetables to the birds for pecking. In conclusion, welfare needs in terms of good feeding, house temperature, and litter quality were met. However the stocking density was high and there was minimum attempt to provide facilities for normal behaviour (perches and sand bathing boxes). The overall assessment was that the welfare of the birds was compromised because some of their requirements were not met.