Long-term impacts of grazing on indigenous forest remnants on North Island hill country, New Zealand

Small isolated patches of native forest surrounded by extensive pastoral grasslands, characteristic of many New Zealand rural landscapes, represent an important reservoir of lowland biodiversity. Improved management of them is a major focus of biodiversity conservation initiatives in New Zealand. We quantified the long-term impacts of grazing on indigenous forest remnants in hill country at Whatawhata, western Waikato, North Island. Structure and composition were compared between forest fragments grazed for >50 years and nearby ungrazed continuous forest. Grazed fragments had shorter and less shady canopies, sparser understoreys, tree populations with larger mean diameters, and ground layers with lower cover of litter and higher cover of vegetation and bare soil than continuous forest. Fragments also had lower indigenous-plant species richness, especially in sapling and seedling populations, and almost no palatable indigenous shrubs, terrestrial orchids, and ferns that require high humidity (e.g. Hymenophyllum spp.), but contained many indigenous and adventive herbaceous species. A transition appears to be occurring in grazed fragments from tall, long-lived trees like Beilschmiedia tawa and Dysoxylum spectabile to short and shorter-lived trees like Kunzea ericoides, Melicytus ramiflorus, and Dicksonia squarrosa. Because grazing inhibits most regeneration processes, unfenced remnants of conifer–broadleaved forest are unlikely to be maintained in grazed pasture in the long term.     

Density-dependent grazing impacts of introduced European rabbits and sympatric kangaroos on Australian native pastures

Little information is available on relationships between pest animal density and damage in natural ecosystems. Introduced European rabbits, Oryctolagus cuniculus, cause severe damage to Australian native vegetation but density–damage relationships are largely unexplored. There are no recognized simple methods to estimate their impacts on native pastures, due in part to confusion with grazing impact of other herbivores. We tested simple quantitative sampling methods using multiple small quadrats to detect site differences in pasture cover, pasture species richness and dung pellet density of herbivores, from which rabbit density and relative abundance of larger herbivores were estimated. Native pasture cover and species richness declined exponentially with increasing rabbit density, within the range of 0–5 rabbits ha^?1, while cover of unpalatable exotic pasture species increased. By contrast, kangaroo abundance was positively related to palatable native pasture cover and negatively related to cover of unpalatable weeds, and had no negative effect on native pasture cover or species richness that was discernable against a background of low to moderate rabbit densities. Perennial native forbs and perennial grasses replaced invasive Wards weed as the dominant ground cover at low rabbit densities. We conclude that, regardless of previous grazing history, contemporary kangaroo grazing pressure and weed invasion, the severely degraded state of native pastures was perpetuated by rabbits. The effect of rabbits on native pasture can be recorded in a simple manner that is suitable for identifying density–damage relationships in the presence of other herbivores and changes over time. This method is seen as particularly useful in setting target densities below which rabbits must be managed to maintain native plant communities and ecosystem function in southern Australia. It may also be useful to demonstrate rabbits’ impacts in other regions, including optimum densities for plant biodiversity benefits in their native European range.     

Beetle assemblages of kahikatea forest fragments in a pasture- dominated landscape

Fragments of kahikatea (Dacrycarpus dacrydioides) forest provide a major opportunity for conservation of indigenous biodiversity in the heavily deforested landscape of the Waikato Basin, New Zealand. However, there is little documented information on what indigenous fauna survives in these fragments. Using Malaise traps set 20 m and 50 m into fragments and 20 m and 50 m into the adjacent pasture, we analysed the beetle (Coleoptera) assemblages associated with two such kahikatea forest fragments in the south Waikato Basin in order to determine the scope of biotic invasion by adventive species and use of the surrounding pasture by indigenous species. A total of 3706 beetles were caught, encompassing 37 families and 206 recognisable taxonomic units. The forest fragments had a sharply defined edge, and were dominated by indigenous beetle species, with only a few adventive species present. Beetle assemblages sampled in the surrounding pasture were numerically dominated by adventive species. Despite no indigenous plant species being present in the pastures, 55 indigenous beetles species (61% of total species sampled in the pasture) were recorded in this habitat. Traps in the pasture of greatest floral diversity caught the most indigenous beetle species. Beetles of the detritivore guild dominated the samples from forest, but in samples from pasture, detritovores and predatores were co-dominant. Indigenous herbivore species were poorly represented in samples from pasture compared to other guilds. The kahikatea fragments have a rich indigenous beetle fauna and represent important refuges in the pastoral landscape of the Waikato. Many indigenous species are utilising the pasture to some degree, although their abundance and species richness declines with distance from the forest edge. This may have implications for successful dispersal to new patches. Species that could potentially be used as indicators of kahikatea forest fragment community structure and its resistance to invasion are suggested.     

Rainforest seed rain into abandoned tropical Australian pasture is dependent on adjacent rainforest structure and extent

It is well known that the recovery of abandoned tropical pastures to secondary rainforest benefits from the arrival of seeds from adjacent rainforest patches. Less is known, however, about how the structural attributes of adjacent rainforest (e.g. tree density, canopy cover and tree height) impact seed rain patterns into abandoned pastures. Between 2011 and 2013, we used seed traps and ground seed surveys to track the richness and abundance of rainforest seeds entering abandoned pastures in Australia's wet tropics. We also tested how seed rain diversity is related to the distance from forest, the proportion of forest cover in the landscape and several structural attributes of adjacent forest patches, specifically average tree height, canopy cover, tree species richness and density. Almost no seeds were captured in elevated pasture seed traps, even near forest remnants. Abundant forest seeds were found in ground surveys but only within 10 m of forest edges. In ground surveys, seeds from wind‐dispersed species were more abundant, but less species rich, than animal‐dispersed species. A survey of pasture seedling recruits suggested that some forest seeds must be dispersing more than 10 m into pasture at very low frequencies, but only a few species are establishing there. Recruits were predominantly animal‐dispersed not wind‐dispersed species. In addition to distance from forest and the proportion of forest within a 100‐ to 200‐m radius of sampling sites, the richness and density of adjacent forest trees were the most important factors for explaining the probability of seed occurrence in abandoned pastures. Results suggest that without some restoration assistance, the recovery of abandoned pastures into secondary rainforest in Australia's tropical rainforests will likely be limited, at least in part, by a very low rate of seed dispersal away from forest edges and by the diversity and density of trees in adjacent remnant forests.     

Resilience of New?Zealand indigenous forest fragments to impacts of livestock and pest mammals

A number of factors have combined to diminish ecosystem integrity in New?Zealand indigenous lowland forest fragments surrounded by intensively grazed pasture. Livestock grazing, mammalian pests, adventive weeds and altered nutrient input regimes are important drivers compounding the changes in fragment structure and function due to historical deforestation and fragmentation. We used qualitative systems modelling and empirical data from Beilschmiedia tawa dominated lowland forest fragments in the Waikato Region to explore the relevance of two common resilience paradigms ? engineering resilience and ecological resilience ? for addressing the conservation management of forest fragments into the future. Grazing by livestock and foraging/predation by introduced mammalian pests both have direct detrimental impacts on key structural and functional attributes of forest fragments. Release from these perturbations through fencing and pest control leads to partial or full recovery of some key indicators (i.e. increased indigenous plant regeneration and cover, increased invertebrate populations and litter mass, decreased soil fertility and increased nesting success) relative to levels seen in larger forest systems over a range of timescales. These changes indicate that forest fragments do show resilience consistent with adopting an engineering resilience paradigm for conservation management, in the landscape context studied. The relevance of the ecological resilience paradigm in these ecosystems is obscured by limited data. We characterise forest fragment dynamics in terms of changes in indigenous species occupancy and functional dominance, and present a conceptual model for the management of forest fragment ecosystems.     

Effects of grazing on plant communities and successional processes vary along an aridity gradient at a northern temperate grassland

The intermountain grasslands of North America reach their most northern geographic extent in interior British Columbia’s Cariboo-Chilcotin region. Here, this study examined the long-term effects of livestock grazing exclusion and reductions in grazing severity on plant community characteristics including plant and litter cover, species richness and abundance of leading species of 33 grassland sites across a broad aridity and soil property gradient. Across the aridity gradient, grazing reduced species richness, plant cover, and litter cover. However, the effects of grazing on dominant species varied across the gradient. In more arid grasslands, historical grazing substantially reduced cover of late-seral native bunchgrass Psuedoroegnaria spicata, and repeated measurements indicate that very long time periods are necessary for successional processes associated with recovery of native bunchgrasses. At the cool-wet end of the aridity gradient, successional processes are more rapid but dominated by exotic species Poa pratensis and Tragopogon pratensis. Recent (past 20 years) light grazing and rest-rotation have favored Poa pratensis at the expense of native needlegrasses (Achnatherum spp. and Hesperostipa spp.). We suggest that absence of a dominant large-stature native bunchgrass for mesic grasslands was a key factor in the invasion and dominance of Poa pratensis.

     

Recovery of Tawa-dominated forest fragments in the Rotorua Basin, New Zealand, after cessation of livestock grazing

Summary   Tawa ( Beilschmiedia tawa )-dominated forest fragments on farms within the Rotorua Basin were surveyed to quantify the likely recovery processes following exclusion of domestic livestock grazing, using a space-for-time substitution approach. Vegetation structure, plant diversity and soil fertility were measured at 24 sites within 15 forest fragments on six farms, covering a range in time since exclusion from grazing of 1–53 years. The forest fragments were compared with a large area of ungrazed forest in the nearby Lake Okataina Scenic Reserve. As time since exclusion from grazing increased, indigenous plant species diversity increased (up to 30–35 years); ground fern and epiphyte abundance increased (up to 30–35 years); tree seedling and sapling numbers, and litter cover also increased (up to 10–15 years); and overall tree numbers increased, while average tree diameter at breast height and overall tree basal area did not differ significantly. The soil fertility status was highly variable, obscuring clear patterns, although Olsen P status decreased with time since grazing exclusion. Once grazing of forest fragments ceases, significant changes in their diversity, structure and soil characteristics can be expected, which indicate recovery of these plant communities towards the conditions observed in ungrazed forest.     

The Effect of Spatial Structure of Pasture Tree Cover on Avian Frugivores in Eastern Amazonia

The movement of frugivores between remnant forests and successional areas is vital for tropical forest tree species to colonize successional habitats. The response of these species to the spatial structure of pasture tree cover is largely unknown. We studied avian frugivores that were found in primary forest edges and large pastures in eastern Amazonia, Brazil. We determined how the small‐scale spatial structure of pasture trees at forest edges affects five response variables: bird presence, visitation rate, duration of visit, species richness, and an index accounting for species’ level of frugivory and abundance in forests. We used hierarchical linear models to estimate the effect of four predictor variables on response variables: (1) clustering of pasture trees; (2) percent canopy cover of pasture trees; (3) distance of pasture tree to forest edge; and (4) tree crown area. The study species, many of which are widely distributed in the Neotropics, were generally insensitive to percent cover and clustering of trees. Frugivore visitation to individual trees remained constant as cover increased. Visitation was positively correlated with focal tree distance to forest edge and crown area. The positive relationship between distance and visitation rates may be due to the increased abundance of some resource further from forests. If pastures were abandoned the distance from forest edges would not likely limit frugivore visitation and seed deposition under large pasture trees in our study (i.e., up to 200 m distant).     

Short-term responses of rehabilitating coastal dune forest ground vegetation to livestock grazing

We investigated the responses of the ground vegetation in a 17‐year‐old coastal dune forest plant community to four levels of experimentally applied livestock grazing (three grazing levels and one ungrazed control) from May 1994 to March 1996. The effects of grazing were apparently subordinate to site‐specific intrinsic vegetation change and there were some indications that rainfall interacted with grazing level. Grazing had some apparent but no significant effects on plant species composition, significantly affected plant species richness over time, and significantly increased the range of species richness and vegetation cover values as well as the relative abundance and numbers of plant species with erect growth forms. Vegetation cover changed significantly over time, independently of grazing. Our results point to two important, easily measured mechanisms for the conservation management of coastal dune forests – the interaction of disturbance type with plant growth form and the increase of variation in community structural variables under disturbance. These mechanisms, although they potentially have wide application and predictive power, have not been studied adequately.     

Untangling the effects of fire, grazing, and land-use legacies on grassland butterfly communities

Many grassland ecosystems are disturbance-dependent, having evolved under the pressures of fire and grazing. Restoring these disturbances can be controversial, particularly when valued resources are thought to be disturbance-sensitive. We tested the effects of fire and grazing on butterfly species richness and population density in an economically productive grassland landscape of the central U.S. Three management treatments were applied: (1) patch-burn graze—rotational burning of three spatially distinct patches within a pasture, and moderately-stocked cattle grazing (N?=?5); (2) graze-and-burn—burning entire pasture every 3?years, and moderately-stocked cattle grazing (N?=?4); and (3) burn-only—burning entire pasture every 3?years, but no cattle grazing (N?=?4). Butterfly abundance was sampled using line transect distance sampling in 2008 and 2009, with six 100-m transects per pasture. Butterfly species richness did not respond to management treatment, but was positively associated with pre-treatment proportion of native plant cover. Population density of two prairie specialists (Cercyonis pegala and Speyeria idalia) and one habitat generalist (Danaus plexippus) was highest in the burn-only treatment, whereas density of one habitat generalist (Cupido comyntas) was highest in the patch-burn graze treatment. Treatment application affected habitat structural characteristics including vegetation height and cover of bare ground. Historic land uses have reduced native plant cover and permitted exotic plant invasion; for some butterfly species, these legacies had a greater influence than management treatments on butterfly density. Conservation of native insect communities in altered grasslands might require native plant restoration in addition to restoration of disturbance processes.     

Relationships between the diversity patterns of vascular plants,lichens and invertebrates in the Central Asian forest-steppe ecotone

The Central Asian forest-steppe ecotone has been exposed to large alterations in grazing pressure in the last two decades, but the consequences for biodiversity have not been studied so far. We analyzed the biodiversity of the edges and the interior of Siberian larch forests in the forest-steppes of eastern Kazakhstan (Saur, Kazakh Altai) and western Mongolia (Mongolian Altai, Khangai) across different groups of organisms (vascular plants, epiphytic lichens, soil macroarthropods, oribatid mites, moths). The species richness of these groups was related to each other only at the forest edge, but not in the interior. Species richness of vascular plants, soil macroarthropods and oribatid mites at the forest edges was positively correlated. This indicates that these ground-inhabiting groups of organisms responded similarly to the variation in the grazing pressure of livestock, which is kept at spatially varying densities by mostly nomadic or transhumant herders. The species richness of epiphytic lichens was only positively correlated with that of vascular plants, and the richness of the (volant) moths was not correlated with that of any other group. The complete lack of correlation between the diversity of groups of organisms in the forest interior suggests that the diversity of the five studied groups is controlled by specific environmental factors, including light and moisture. Except for the Mongolian Altai, which was subjected to the highest grazing pressure, vascular plants, lichens, soil macroarthropods, and moths had a higher diversity at the edges than in the interior; the opposite was true for the oribatid mites. The latter probably benefit from the higher soil moisture inside the forest, whereas the other four groups are favored by increased availability of light, the proximity to the steppe with a partial mixing of species pools, and the soil macroarthropods also by increased dung abundance.     

The impact of forest ski-pistes on diversity of ground-dwelling arthropods and small mammals in the Alps

Forest clearing for winter sport activities is the major force driving loss and fragmentation of the alpine forests. The establishment of ski-pistes involves impacts on every ecosystem component. To assess the extent of this threat we studied ground-dwelling arthropods (namely ground beetles and spiders) and small mammals (shrews and voles) at two ski resorts in north-western Italian Alps by pitfall trapping. Diversity parameters (mean abundance, species richness and Shannon index) of spiders and macropterous carabids increased from forest interior to open habitats (i.e., ski-piste or pasture), whereas parameters of brachypterous carabids significantly decreased from forest interior to open habitats. Diversity parameters of macropterous ground beetles were higher on pastures than on ski-pistes. Small mammals were virtually absent from ski-pistes. Observed frequencies in the three adjacent habitats were significantly different from expected ones for the bank vole Myodes glareolus and the pygmy shrew Sorex minutus. Generalized linear models showed that abundance, species richness and diversity of spiders and macropterous carabids of ski-pistes were best modelled by combination of factors, including grass cover and width of the ski-piste. Indicator Species Analysis showed that species that significantly preferred ski-pistes were less than those preferring pastures, and species which were exclusive of ski-pistes were very few. To retain arthropod ground-dwelling fauna of open habitats environmentally friendly ways of constructing pistes should be developed. After tree clearing, only the roughest ground surfaces should be levelled, in order to preserve as much natural vegetation as possible. Where necessary, ski-pistes should be restored through the recovery of local vegetation.     

Comparison of biodiversity and ground cover between a commercial rotationally grazed property and an adjacent nature reserve in semi‐arid rangeland

Continuous livestock grazing can have negative effects on biodiversity and landscape function in arid and semi‐arid rangelands. Alternative grazing management practices, such as rotational grazing, may be a viable option for broad‐scale biodiversity conservation and sustainable pastoral management. This study compared ground cover, plant species composition and floristic and functional diversity along gradients of grazing intensity between a pastoral property rotationally grazed by goats and an adjacent nature reserve (ungrazed by commercial livestock) in semi‐arid south‐eastern Australia. Understorey plant species composition differed significantly between the rotationally grazed property and the nature reserve, with a greater proportion and frequency of palatable species recorded in the nature reserve. Understorey plant species richness, diversity, functional biodiversity measures and ground cover declined with increasing grazing pressure close to water points under commercial rotational grazing management. However, at a whole‐paddock scale, there were few differences in plant biodiversity and ground cover between the rotationally grazed property and the nature reserve, despite differences in overall plant species composition. Flexible, adaptive, rotational grazing should be investigated further for its potential to achieve both socio‐economic and biodiversity conservation outcomes in semi‐arid rangelands to complement existing conservation reserves.     

Rapid short-tussock grassland decline with and without grazing, Marlborough, New Zealand

Species abundance, species richness, and ground cover were measured over 10 years on nine paired grazed and exclosure plots in short-tussock grassland in the early stages of invasion by Hieracium species. With and without grazing, H. pilosella and H. caespitosum increased markedly and H. lepidulum increased locally. In contrast, 50% of all other common species and species groups, and total, native, and exotic species richness declined significantly. Exclusion increased or had no effect on rates of increase in Hieracium species and rates of decline in short tussocks, and did not reduce rates of decline in other species. Exclusion had no effect on decline in native species richness, but mainly accelerated declines in total and exotic richness. Declines in 13 key vegetation variables were significantly predicted by increase in Hieracium abundance, suggesting competitive exclusion. With or without grazing, Hieracium species will become more dominant and other species will continue to decline. The effects of large herbivores on plant species diversity can often be predicted from site productivity. Our results indicate the need also to account for species origin, spatial scale, time, and exotic invasion.     

Plant species diversity and forage quality as affected by pasture management and simulated cattle activities

Grazed pastures have been historically used in Japan for animal production with little concern to biodiversity. However, pasturing has significant effects on biodiversity and productivity because it produces gaps in the distribution of vegetation due to animal activities. We hypothesized that different grazing activities would have effects on the diversity of plant species and forage quality in different ways and that the sward type would modify these effects. Therefore, we attempted to predict the diversity of plant species and changes in total nutrient content per area at the time since treatment on the basis of simulations of cattle activities in three pastures with different vegetation compositions. We created three ground types (grazed areas, cleared ground, and undisturbed areas) in three pastures (improved, partially improved semi-natural, and semi-natural pasture) and recorded the percentage cover of each plant within the plots. We repeatedly calculated the biodiversity indices from these community data by varying the sampling probabilities for each ground type, which provided us with the expected species diversity indices with the changing proportions of each ground type. Furthermore, we investigated the dry matter and forage qualities. For improved and partially improved semi-natural pasture, our models predicted that plant diversity increased as a saturating function of the proportion of cleared ground and grazed area relative to the undisturbed area, although our models also showed exponential curves for the semi-natural pasture. Forage samples from cleared ground plots and semi-natural pasture had the lowest forage quality among all pastures. Based on the predicted effects of cattle pasturing on the plant species biodiversity and forage quality, it may be more beneficial to maintain a small proportion of cleared ground in the improved pasture during intensive grazing.     

Small-scale species richness and its spatial variation in an alpine meadow on the Qinghai-Tibet Plateau

We investigated how the high small-scale species richness of an alpine meadow on the Qinghai-Tibet Plateau, China, is maintained. This area is characterized by strong wind and severe cold during long winters. In winter, most livestock is grazed on dead leaves in small pastures near farmers’ residences, whereas in the short summer, livestock is grazed in mountainous areas far from farmers’ residences. The number of plant species and the aboveground biomass were surveyed for three adjacent pastures differing in grazing management: a late-winter grazing pasture grazed moderately from 1 February to 30 April, an early-winter grazing pasture grazed lightly from 20 September to late October, and a whole-year grazing pasture grazed intensively throughout the entire year. In each pasture, we harvested the aboveground biomass from 80 or 100 quadrats of 0.01 m² along a transect and classified the contents by species. We observed 15.5–19.7 species per 0.01 m², which is high richness per 0.01 m² on a worldwide scale. The species richness in the two winter grazing pastures was higher than that in the whole-year grazing pasture. The spatial variation in species richness and species composition in the two winter grazing pastures in which species richness was high was greater than that in the whole-year grazing pasture in which species richness was lower. Most of the leaves that are preserved on the winter grazing pastures during summer are blown away by strong winds during winter, and the remaining leaves are completely exhausted in winter by livestock grazing. A pasture with a high richess is accompanied by a high spatial variation in species richness and species composition. There is a high possibility that the characteristic of spatial variation is also caused by traditional grazing practices in this area.     

Plant species richness responses to grazing protection and degradation history in a low productivity landscape

Questions: Does species richness and abundance accumulate with grazing protection in low productivity ecosystems with a short evolutionary history of grazing, as predicted by emerging theory? How do responses to grazing protection inform degradation history? Location: Mulga (Acacia aneura) dry forest, eastern Australia, generally considered chronically degraded by livestock grazing. Methods: Three paired exclosures (ungrazed, and macropod‐grazed) were compared with open‐grazed areas after 25 years using quadrats located on either side of the fences. Additionally, the regional flora for mulga dry forest was assessed to identify species that may have declined and could be threatened by grazing. Results: Low herbaceous biomass accumulation (<1.3 t ha^?1) with full grazing protection confirmed a low productivity environment. For most plant life forms the highest species richness was in macropod‐grazed exclosures, an intermediate grazing disturbance that best approximates the evolutionary history of the environment. This was the net outcome of species that both declined and increased in response to grazing. Regeneration and subsequent self‐thinning of mulga was promoted with grazing protection, but did not confound interpretation of species richness and abundance responses. At the regional scale only 11 native species out of 407 comprising the mulga dry forest flora were identified as rare and potentially threatened by grazing. Conclusions: Significant increases in richness or abundance of native plants with grazing protection, persistence of perennial grasses, regeneration of mulga and scant evidence of a major decline in the regional flora are not consistent with established assertions that long‐grazed mulga dry forest has crossed functional thresholds that limit recovery. Further, a peak in species richness under intermediate (macropod) grazing is counter to the shape of the response predicted by emerging theory for recovery of species richness in a low productivity environment. The finding prompts a more thorough understanding of the distinction between environments with inherently low productivity and those degraded by grazing.     

Floristic changes over 30 years in a Canterbury Plains kānuka forest remnant, and comparison with adjacent vegetation types

The Canterbury Plains have lost most of their pre-Polynesian indigenous vegetation, primarily forest and shrubland. One of the few remaining areas is the 2.3 ha Eyrewell Scientific Reserve which consists mostly of low kānuka (Kunzea ericoides) forest and a small area of grassland. We assessed the Reserve vegetation using a combination of plots and transect surveys at different times of the year between 2001–2003. For comparison with the Reserve vegetation we also assessed plots in an adjacent grazed kānuka remnant, adjacent cultivated pasture and Eyrewell Forest, a pine plantation. Our study of the Eyrewell Reserve in 2001–2003 found that since an assessment of the Reserve in 1972, 28 indigenous species were no longer present but 14 indigenous species and 48 adventive species were newly recorded. The dramatic invasion of the Reserve is illustrated by the fact that 60% of the 118 species recorded in 2003 were adventives compared to 34% in 1972. Despite this invasion and the loss of indigenous species, Reserve plots still have more than twice as many species as plots in the adjacent pine plantation. The Reserve also included several species of high conservation value such as the “Chronically Threatened” Leptinella serrulata, and the “At Risk” Aciphylla subflabellata, Coprosma intertexta and Pterostylis tristis. Plots in the Reserve grassland and adjacent pasture had the lowest percentage of indigenous species of all habitat types, with the pasture plots having no indigenous vascular plant species. In contrast the understorey of the old pine stands had the highest percentage of indigenous species of any of the habitats and in places was dominated by kānuka up to 4 m tall, indicating that these plantations also have conservation value. Eyrewell Reserve and the few other remaining kānuka remnants in the Canterbury Plains represent an important pool of indigenous species for conservation. Options for the future management of the Reserve are discussed.     

Effects of livestock breed and grazing pressure on ground‐dwelling arthropods in Cantabrian heathlands

Abstract 1. The effects of different goat breeds and grazing pressures on epigeal arachnids (Lycosidae and Opiliones) and ground beetles (Carabidae) were assessed in a heath–gorse shrubland located in the north of the Iberian Peninsula. Three treatments (low grazing pressure with Cashmere breed, high grazing pressure with Cashmere breed, and high grazing pressure with local Celtiberic breed) with three replicates of each treatment were allocated randomly to nine plots. 2. Arthropod fauna abundance, diversity, and species richness were estimated using pitfall trapping over 3 years (2003, 2004, and 2005). Vegetation cover, composition, and height were assessed along transects and above‐ground plant biomass was sampled in quadrats. 3. Lower grazing pressure led to lower herbaceous cover and higher heather cover than high grazing pressure. Overall, it did not enhance arthropod diversity or abundance, but the abundance and species richness of carabids, and abundance of lycosids like Pardosa pullata, were higher under high stocking rates, whereas Opiliones were favoured by the low stocking rates. Although it has been assumed that traditional breeds enhance biodiversity, the present study found no significant differences for both arthropod fauna and vegetation between the goat breeds. 4. Arthropod–vegetation relationships were examined by constrained ordination. Fauna assemblages followed a gradient from closed canopy shrubland areas, in the lowest grazing pressure, to grassier open canopy areas resulting from higher grazing pressure, revealing the importance of grazing management as a driver of arthropod community structure of the heathland.     

Slow recovery in desert perennial vegetation following prolonged human disturbance

Questions: How long may it take for desert perennial vegetation to recover from prolonged human disturbance and how do different plant community variables (i.e. diversity, density and cover) change during the recovery process? Location: Sonoran Desert, Arizona, USA. Methods: Since protection from grazing from 1907 onwards, plant diversity, density and cover of perennial species were monitored intermittently on ten 10 m × 10 m permanent plots on Tumamoc Hill, Tucson, Arizona, USA. Results: The study shows an exceptionally slow recovery of perennial vegetation from prolonged heavy grazing and other human impacts. Since protection, overall species richness and habitat heterogeneity at the study site continued to increase until the 1960s when diversity, density and cover had been stabilized. During the same period, overall plant density and cover also increased. Species turnover increased gradually with time but no significant relation between any of the three community variables and precipitation or Palmer Drought Severity Index (PDSI) was detected. Conclusions: It took more than 50 yr for the perennial vegetation to recover from prolonged human disturbance. The increases in plant species richness, density, and cover of the perennial vegetation were mostly due to the increase of herbaceous species, especially palatable species. The lack of a clear relationship between environment (e.g. precipitation) and community variables suggests that site history and plant life history must be taken into account in examining the nature of vegetation recovery processes after disturbance.