Patterns and Drivers of Scattered Tree Loss in Agricultural Landscapes: Orchard Meadows in Germany (1968-2009)

Scattered trees support high levels of farmland biodiversity and ecosystem services in agricultural landscapes, but they are threatened by agricultural intensification, urbanization, and land abandonment. This study aimed to map and quantify the decline of orchard meadows (scattered fruit trees of high nature conservation value) for a region in Southwestern Germany for the 1968 2009 period and to identify the driving forces of this decline. We derived orchard meadow loss from 1968 and 2009 aerial images and used a boosted regression trees modelling framework to assess the relative importance of 18 environmental, demographic, and socio-economic variables to test five alternative hypothesis explaining orchard meadow loss. We found that orchard meadow loss occurred in flatter areas, in areas where smaller plot sizes and fragmented orchard meadows prevailed, and in areas near settlements and infrastructure. The analysis did not confirm that orchard meadow loss was higher in areas where agricultural intensification was stronger and in areas of lower implementation levels of conservation policies. Our results demonstrated that the influential drivers of orchard meadow loss were those that reduce economic profitability and increase opportunity costs for orchards, providing incentives for converting orchard meadows to other, more profitable land uses. These insights could be taken up by local- and regional-level conservation policies to identify the sites of persistent orchard meadows in agricultural landscapes that would be prioritized in conservation efforts.     

Evaluating alternative mowing regimes for conservation management of Central European mesic hay meadows: A field experiment

Conservation status of hay meadows highly depends on their management. The main goal of this study was to assess the efficiency of different mowing regimes in maintenance of plant species richness and diversity of mesic hay meadows. The field experiment was carried out on a species rich, mesic hay meadow in Western Hungary. We evaluated the effects of four alternative types of management on the plant community after 7 years of continuous treatment: (1) mowing twice a year, typical traditional management, (2) mowing once a year in May, most practised currently by local farmers, (3) mowing once a year in September, often proposed for conservation management and (4) abandonment of mowing. Traditional mowing resulted in significantly higher number and higher diversity of vascular plant species than other mowing regimes. Mowing twice a year was the only efficient way to control the spread of the invasive Solidago gigantea, and mowing in September was more successful in it than mowing in May. We conclude that the traditional mowing regime is the most suitable to maintain botanical diversity of mesic hay meadows; however, other regimes should also be considered if certain priority species are targeted by conservation.     

Extinction debt in naturally contracting mountain meadows in the Pacific Northwest,USA: varying responses of plants and feeding guilds of nocturnal moths

Fire suppression and climate change are leading to habitat fragmentation in temperate montane meadows across the globe, raising concerns about biodiversity loss. Restoration strategies may depend on the rate and nature of species response to habitat loss. We examined the effects of habitat loss and fragmentation on plants and nocturnal moths in natural montane meadows in the western Cascades, Oregon, USA, using generalized additive mixed models, non-metric multidimensional scaling, and multiple response permutation procedure. Historic (1949) rather than current (2005) meadow size explained species richness of herbaceous plants and herb-feeding moths and meadow plant community structure, indicating that loss of meadow species may be delayed by many decades following loss of meadow habitat, resulting in an extinction debt. In contrast, abundance of herb-feeding moths and species richness and abundance of woody plant-feeding moths were related to recent meadow configuration: as meadows are invaded by woody plants, abundance of meadow species declines, and woody plants and associated moths increase. Despite decades of fire suppression and climate change, montane meadows in many temperate mountain landscapes may still be amenable to restoration.     

Domestic pig uprooting emerges as an undesirable disturbance on vegetation and soil properties in a plateau wetland ecosystem

Pig disturbances are recognized as key factors influencing the structure of ecosystems. Cage-free domestic pig (Sus scrofa domestica) searching for food by uprooting vegetation is emerging as a threat to wetlands located in Qinghai-Tibet Plateau. As a unique and fragile ecosystem, the ecological impacts of pig uprooting (PR) here remain unclear. Here, we examined vegetation and soil properties under PR in the meadows of a plateau wetland, Napahai. Quadrat surveys and sampling were taken during the late growing season (September) of 2014 at three sites: one was seasonally flooded (wet meadow) and the other two were unflooded (dry meadows). Compared to controls (pig-undisturbed patches), plant biomass and density decreased (p < 0.001), while soil bulk density increased (p < 0.05) for all sites under PR. In addition, divergent responses to pig disturbances were observed in different sites. In the wet meadow, PR caused a shift in vegetation from Blysmus sinocompyessus, a dominant perennial herb towards the annual hydrophyte Polygonum hydropiper. In the two dry meadows, the dominant species remained unchanged, but nutrients stored in soils were severely reduced by PR, accelerating the soil impoverishment when compared to the wet meadow. Overall, PR impacts on local ecosystems are largely dependent on the moisture characteristics of micro-habitats, and proper management should be taken to counteract ecosystem degradation, especially in dry meadows.     

Predictive mapping of Meadow Pipit density using integrated remote sensing data and an atlas of vascular plants dataset

Capsule The highest densities of Meadow Pipits in Central Europe are found in lowland and upland wet meadows.

Aims To create a large-scale predictive model of Meadow Pipit density.

Methods We analysed factors affecting the density of the Meadows Pipit in Poland using data from 777?×?1?km study plots and a set of 22 environmental variables, including agriculture intensification and habitat-specific plant species as classifiers of meadow types. Predictors were selected using variation inflation factor, then related to species density data using generalized additive models.

Results The best-supported model included 11 variables and was clearly better (Akaike information criterion weight?=?0.47) than other models. The density of the Meadow Pipit reaches its highest levels on large areas of extensively used wet meadows as well as pastures where livestock graze and which show high photosynthetic activity in April.

Conclusion Some aspects of the environment that were not identified from remote sensing data were vital for determining relatively high density. Conservation efforts for preserving Meadow Pipit populations should focus on maintaining wet meadows and extensively grazed pastures. Given the results, the Meadows Pipit may be classified as a good indicator of traditional agriculture.     

How is Regeneration of Plants after Mowing Affected by Shoot Size in Two Species-Rich Meadows with Different Water Supply?

Mowing a meadow is an example of an equalizing process that reduces differences among species by removing aboveground biomass approximately 5 cm above ground. This regular disturbance that affects all plants prevents competitive exclusion of small species and thus allows coexistence of numerous species differing in shoot size. In this paper we search for the mechanism behind this by comparing the shoot biomass of 41 common species in dry and wet species-rich meadows in mown and recently abandoned plots in June (before mowing) and in October. We asked the following questions: i) Do the plants differ in proportion of biomass lost by mowing? ii) Are the mown plants able to compensate for biomass lost by mowing? iii) Is the compensatory ability of mown plants related to their size? iv) Is the compensatory ability of plants related to severity of disturbance (removed biomass)? v) Does water availability in meadows affect these features? Our results revealed that the earlier explanation of equalization of meadow plants after mowing due to the proportionally larger biomass loss in larger plants than small plants does not represent the entire mechanism. Even when larger plants in the wet meadow lost more biomass, the proportion of lost biomass was not dependent on plant size, and compensation ability (growth of mown in comparison with unmown plants) was not related to the lost biomass in this meadow type. On the contrary, the observed pattern could be explained by different compensation abilities of small versus tall plants. In addition, according to our expectations, the compensation for lost biomass in the wet meadow was higher than in the dry one.     

Relationship of plant diversity with litter and soil available nitrogen in an alpine meadow under a 9-year grazing exclusion

Grazing exclusion is widely used globally to restore degraded grasslands. Plant diversity has important impacts on grassland ecosystem functions, including grassland productivity and carbon storage. In this study, we selected a Kobresia meadow on the Qinghai–Tibetan Plateau to investigate how grazing exclusion affects plant diversity. Inorganic nitrogen (NH₄ ⁺ and NO₃ ^?) was also measured because its availability impacts plant growth. We found that plant diversity in the meadow was significantly lower under grazing exclusion (fenced meadow) for 9 years compared with moderate grazing. Accumulated litter was significantly higher under grazing exclusion (386.41 g m^?2) compared with grazing (58.77 g m^?2). Soil inorganic nitrogen at 0–5 cm depth was significantly higher under grazing exclusion (13.60 × 10^?2 g kg^?1) than under grazing (9.40 × 10^?2 g kg^?1). The composition of the four functional groups (grasses, sedges, legumes, and forbs) might alter in response to significant changes in the amount of litter and soil available nitrogen content under grazing exclusion compared with grazing. However, the enhanced soil available nitrogen content showed weak feedbacks on plant diversity. In conclusion, light limitation induced by increased amounts of litter may be the main factor causing decreased plant diversity in grazing-excluded meadows compared with moderately grazed meadows.     

What lies beneath: Why knowledge of belowground biomass dynamics is crucial to effective seagrass management

Conservation of seagrasses meadows is important, because these habitats are ecologically important and under threat. Monitoring and modelling are essential tools for assessing seagrass condition and potential threats, however there are many seagrass indicators to choose from, and differentiating between natural variability and declining conditions poses a serious challenge. Tropical seagrass meadows in the Indo-Pacific, in contrast to most temperate meadows, are characterized by a multi-species composition and a year-round growth. Differences in characteristics between species growing within one meadow could induce uncertainty in the assessment of the dynamics of these meadows if variation in productivity and related biomass turnover timescales are not taken into consideration. We present data on biomass distribution, production and turnover timescales of above- and belowground tissues for three key tropical seagrass species (Thalassia hemprichii, Cymodocea rotundata and Halodule uninervis) in two mixed-species meadows in the Spermonde Archipelago, Indonesia. Seagrass leaf turnover time scales were comparable for the three studied seagrass species and varied between 25 and 30 days. Variation in leaf and rhizome turnover timescales were small (or insignificant) between the two meadows. In contrast, rhizome turnover time scales were around ten times longer than leaf turnover timescales, and large differences in rhizome turnover time scales (200–500 days) were observed between the species. The late-successional species T. hemprichii had much slower rhizome turnover compared to the two early successional species. Furthermore, since rhizome biomass has a much longer turnover time compared to leaf biomass, changes in rhizome biomass reflect effects on seagrass meadows on a much longer timescale compared to changes in leaf biomass for these tropical meadows. We conclude that belowground biomass dynamics are an important proxy to assess long-term effects of environmental stressors on seagrass ecosystems and should be included in tropical seagrass management programmes.     

Soil carbon stocks and quality across intact and degraded alpine wetlands in Zoige,east Qinghai-Tibet Plateau

The wetlands on the Qinghai-Tibet Plateau are experiencing serious degradation, with more than 90,000 hectares of marshland converted to wet meadow or meadow after 40 years of drainage. However, little is known about the effects of wetland conversion on soil C stocks and the quality of soil organic carbon (SOC) (defined by the proportion of labile versus more resistant organic carbon compounds). SOC, microbial biomass carbon, light fraction organic carbon (LFOC), dissolved organic carbon, and the chemical composition of SOC in the soil surface layer (0–10 cm), were investigated along a wetland degradation gradient (marsh, wet meadow, and meadow). Wetland degradation caused a 16 % reduction in the carbon stocks from marsh (178.7 ± 15.2 kg C m^?2) to wet meadow (150.6 ± 21.5 kg C m^?2), and a 32 % reduction in C stocks of the 0–10 cm soil layer from marsh to meadow (122.2 ± 2.6 kg C m^?2). Wetland degradation also led to a significant reduction in SOC quality, represented by the lability of the carbon pool as determined by a density fractionation method (L _LFOC), and a significant increase in the stability of the carbon pool as reflected by the alkyl-C:O-alkyl-C ratio. ¹³C NMR spectroscopy showed that the labile form of C (O-alkyl-C) declined significantly after wetland degradation. These results assist in explaining the transformation of organic C in these plateau wetland soils and suggest that wetland degradation not only caused SOC loss, but also decreased the quality of the SOC of the surface soil.     

The role of disturbance in promoting the spread of the invasive seaweed Caulerpa racemosa in seagrass meadows

Human disturbances, such as anchoring and dredging, can cause physical removal of seagrass rhizomes and shoots, leading to the fragmentation of meadows. The introduced green alga, Caulerpa racemosa, is widely spread in the North-West Mediterranean and, although it can establish in both degraded and pristine environments, its ability to become a dominant component of macroalgal assemblages seems greater in the former. The aim of this study was to estimate whether the spread of C. racemosa depends on the intensity of disturbance to the canopy structure of Posidonia oceanica. A field experiment was started in July 2010 when habitat complexity of a P. oceanica meadow was manipulated to simulate mechanical disturbances of different intensity: rhizome damage (High disturbance intensity = H), leaf removal (Low disturbance intensity = L), and undisturbed (Control = C). Disturbance was applied within plots of different size (40 × 40 cm and 80 × 80 cm), both inside and at the edge of the P. oceanica meadow, according to an orthogonal multifactorial design. In November 2011 (16 months after the start of the experiment), no C. racemosa was found inside the seagrass meadow, while, at the edge, the cover of the seaweed was dependent on disturbance intensity, being greater where the rhizomes had been damaged (H) than in leaf removal (L) or undisturbed (C) plots. The results of this study indicate that physical disturbance at the margin of seagrass meadows can promote the spread of C. racemosa.     

Aspect-vegetation complex effects on biochemical characteristics and decomposability of soil organic carbon on the eastern Qinghai-Tibetan Plateau

Background

Meadows and shrublands are two major vegetation types on the Qinghai-Tibetan Plateau, but little is known about biochemical characteristics and its relation to decomposability of soil organic carbon (OC) under these two vegetation types. The present study was designed to evaluate effects of aspect-vegetation complex on biochemical characteristics and decomposability of soil OC.

Methods

Two hills were randomly selected; both with vegetation being naturally divided into southward meadows and northward shrublands by a ridge, and soils were sampled at depths of 0–15 and 15–30 cm, along contours traversing the meadow and shrubland sites. Particulate (particle size 2–0.05 mm) OC and nitrogen (N), microbial biomass C and N, non-cellulosic sugars, and CuO lignin were analyzed, and OC mineralization was measured for 49 days at 18 and 25 °C under laboratory incubation, respectively.

Results

More than half of soil OC was present as particulate fraction across all samples, indicating the coarse nature of soil organic matter in the region. Averaging over depths, shrublands contained 87.7???114.1 g OC and 7.7???9.3 g N per kg soil, which were 63???78 and 26???31 % higher than those in meadows, respectively. Meanwhile the C/N ratio of soil organic matter was 11.4???12.3 under shrublands, being 29???40 % higher than that under meadows. Soil OC under meadows was richer in noncellulosic carbohydrates and microbial biomass in the 0–15 and 15–30 cm depths but contained less lignin in the 15–30 cm depth. Ratios of microbially- to plant-derived monosaccharides and between acid and aldehyde of the vanillyl units were greater in soils under shrublands, showing more abundant microbially-derived sugars and microbially-transformed ligneous substances in OC as compared to meadow soils. By the end of 49 days’ incubation, total CO₂–C evolution from soils under meadows was 15.0–16.2 mg g^?1 OC averaging over incubation temperatures and soil depths, being 27–55 % greater than that under shrublands. Across all soil samples over two sites, total CO₂ ? C evolved per g OC at either 18 or 25 °C was closely correlated to enrichments of noncellulosic carbohydrates and microbial biomass. This indicates that the greater soil OC decomposability under meadows was associated with its larger abundances of readily mineralizable fractions compared with shrublands. However, temperature increase effect on soil OC decomposability did not differ between the two types of vegetation.

Conclusions

Our findings suggest that the aspect-vegetation complex significantly affected pool size, biochemical characteristics, and decomposability of soil OC on the northeastern edge of Qinghai-Tibetan Plateau. However, the response of soil OC decomposability to temperature was similar between southward meadows and northward shrublands.     

Nitrous oxide emissions from two alpine meadows in the Qinghai–Tibetan Plateau

Nitrous oxide (N₂O) emission was measured in a Kobresia humilis meadow and a Potentilla fruticosa meadow in the Qinghai–Tibet Plateau from June 2003 to July 2006. Five treatments were setup in the two alpine meadows. Two bare soil treatments were setup in the K. humilis meadow (BSK) and in the P. fruticosa meadow (BSP) by removing the above- and belowground plant biomass. Three plant community treatments were setup with one in the K. humilis meadow (herbaceous community in the K. humilis meadow-HCK) and two in the P. fruticosa meadow (herbaceous community in the P. fruticosa meadow-HCP, and shrub community in the P. fruticosa meadow-SCP). Nitrous oxide emission from BSP was estimated to be 38.1?±?3.6 μg m^?2 h^?1, significantly higher than from BSK (30.2?±?2.8 μg m^?2 h^?1) during the whole experiment period. Rates from the two herbaceous blocks (HCK and HCP) were close to 39.5 μg m^?2 h^?1 during the whole experimental period whereas shrub community (SCP) showed significant high emission rates of N₂O. Annual rate of N₂O emission was estimated to be 356.7?±?8.3 and 295.0?±?11.6 mg m^?2 year^?1 from the alpine P. fruticosa meadow and from the alpine K. humilis meadow, respectively. These results suggest that alpine meadows in the Qinghai–Tibetan Plateau are an important source of N₂O, contributing an average of 0.3 Tg N₂O year^?1. We concluded that N₂O emission will decrease, due to a predicted vegetation shift from shrubs to grasses imposed by overgrazing.     

Surviving in Changing Seascapes: Sediment Dynamics as Bottleneck for Long-Term Seagrass Presence

Changes in the seascape often result in altered hydrodynamics that lead to coinciding changes in sediment dynamics. Little is known on how altered sediment dynamics affect long-term seagrass persistence. We studied the thresholds of sediment dynamics in relation to seagrass presence by comparing sediment characteristics and seagrass presence data of seven separate seagrass meadows. All meadows had a long-term (>20 years) presence. Within these meadows, we distinguish so-called “hotspots” (areas within a meadow where seagrass was found during all mapping campaigns) and “coldspots” (with infrequent seagrass presence). We monitored static sediment characteristics (median grain size, bulk density, silt content) and sediment dynamics (that is, bed level change and maximum sediment disturbance depth), bioturbation (that is, lugworm densities and induced fecal pit and mound relief), and seagrass cover. We statistically analyzed which sediment characteristic best explains seagrass cover. Densely vegetated hotspots were shown to have lower sediment dynamics than sparsely vegetated hotspots and coldspots, whereas static sediment characteristics were similar (grain size, bulk density). The vegetation cover was either low (2–15%) or high (>30%) and sediment dynamics showed a threshold for vegetation cover. From this correlative finding, we postulate a self-sustaining feedback of relatively dense seagrass via sediment stabilization and accordingly a runaway feedback once the seagrass cover becomes too sparse. The sensitivity for sediment dynamics shown in our study implies that future existence of seagrass meadows may be at risk as ongoing climate change might directly (increased environmental extremes) or indirectly (changing seascapes) negatively affect seagrass beds.     

Plant community response to nitrogen and phosphorus enrichment varies across an alpine tundra moisture gradient

Background: The extent to which nutrient availability influences plant community composition and dynamics has been a focus of ecological enquiry for decades.

Aims: Results from a long-term nitrogen (N) and phosphorus (P) addition experiment in alpine tundra were used to evaluate the importance of the two nutrients in structuring plant communities in three communities that differed in their snow cover amounts and duration and soil moisture characteristics.

Methods: A factorial N and P experiment was established in three meadows differing in initial vegetation composition and soil moisture. Plant and soil characteristics were measured after 20 years, and the dissimilarity among meadows and treatments were measured using permutational analysis of variance.

Results: Plant species richness declined uniformly across the three meadow types and in response to N and N + P additions, while both evenness and the Shannon diversity index finding indicated that nutrient additions had the highest impact on moister habitats. Overall, N impacts overshadowed changes attributed to P additions, and the N and N + P plots in wet meadow sites were the least diverse and scored the lowest dissimilarity averages among treatments. Dissimilarity estimates indicated that the control and P plots in the dry meadow community were more distinct in composition than all other plots, and especially those in the moist or wet meadows. Above-ground biomass of grasses and sedges (graminoids) increased with N additions while forbs appeared to show responses dictated in part by the graminoid responses. The most abundant grass species of moist and wet meadow, Deschampsia cespitosa, dominated N and N + P plots of the wet sites, but did not show a N response in moist areas in spite of its general abundance in moist meadow. Competition from other plant species in the moist areas likely diminished the D. cespitosa response and contributed to the resilience of the community to nutrient enrichment.

Conclusions: Initial community composition, as influenced by the specific moisture regime, appears to control the extent to which changes in nutrient resources can alter plant community structure. Long-term fertilization tends to support most but not all findings obtained from shorter-termed efforts, and wet meadows exhibit the largest changes in plant species numbers and composition when chronically enriched with N.     

Mowing may bring about vegetation change,but its effect is strongly modified by hydrological factors

We assessed the effect of long-term (11 years) mowing with a hand scythe on the distributions of plant species and species turnover within meadow communities dominated by Carex acutiformis and C. acuta in a small lowland river valley subjected to annual flooding. We hypothesized that mowing would trigger the process of species exchange toward multispecies communities according to the abiotic environmental gradients, as has been reported for traditionally used wet meadows. We found that mowing had a much greater impact on the increase in plant species abundance in wetter, subjected to deeper and longer flooding, zone of the valley than in its drier part. The treatment and hydrology had no substantial effect on the sedges and cryptogams while the graminoids and the forbs were the least stable components of the plant communities. We found that annual management was conducive to the appearance of numerous seedlings of Alnus glutinosa in the part of wetland situated close to the valley edge. Surface flooding was found to be a driving force modifying the impact of mowing on sedge meadows. This “hydrological resetting impulse” created a specific floristic reset of the community, bringing it to the more simplified forms. Mowing every 4–5 years at the beginning of August is advisable to protect sedge meadows distributed in flooded small lowland river valleys.     

Assessing long-term spatial changes of natural habitats using old maps and archival sources: a case study from Central Europe

Landscapes intensively farmed over a long time period represent a threat for natural habitats and high levels of biodiversity. Information on the historical land use and spatial changes of natural habitats can help to explain the causes of a number of contemporary phenomena, which are important for the development of effective conservation and ecosystem management. This case study from the Czech Republic shows that archival written sources describing landscape quality, including vegetation cover, allow the reclassification of old maps to the level of natural habitat categories (sensu Natura 2000), with the aim of analyzing historic changes in land cover. Significant natural habitat decreases began by the middle of the 19th century. Over the course of 250 years, this area of formerly widespread natural wet meadows has declined by 99 %. An area of water vegetation was reduced by 95 %, willow carrs by 98 %, and a mosaic of willow carrs, wet Cirsium meadow, and alder carrs has decreased by 100 %. These decreases were caused by the conversion of meadows, pastures, and ponds into arable lands. Areas of oak-hornbeam forest, acidophilous oak forest, and thermophilous oak forest were primarily converted into monocultures of coniferous trees. Similarly, the areas with alluvial forests decreased. We conclude that old maps and other archive materials, despite their coarse accuracy, can serve as useful tools for disclosing natural habitat changes and their causes, providing a foundation for formulating biodiversity conservation strategies.     

Why are many anthropogenic agroecosystems particularly species-rich?

Species-rich meadow and pasture habitats are recognised by the European Union Habitats Directive as targets for biodiversity conservation. High species richness is hypothesised to be associated with diversity in plant functional traits and life-history strategies, which are potentially restricted in situations of extremely high and low biomass production. However, variability in functional traits has yet to be investigated across a broad biomass range in nature. We measured variability in a range of functional traits and Grime's competitor, stress-tolerator, ruderal (CSR) strategies for species comprising lowland meadows, subalpine pastures, abandoned grassland and field margins at sites in northern Italy, alongside peak above-ground biomass. The factor most highly and positively correlated with species richness was strategy richness (the number of CSR strategies; Pearson's r = 0.864, P < 0.0001, n = 39), followed by variance in traits involved in leaf resource economics and the timing of flowering. Species richness, trait variance and strategy richness were greatest at intermediate biomass. Thus whilst extremes of biomass production were associated with relatively few taxa exhibiting similar trait values and specialised strategies, greater species richness was apparent in meadows and pastures in which species exhibited divergence in resource economics trait values, reproductive timing and strategy richness.     

Seagrass Herbivory Levels Sustain Site-Fidelity in a Remnant Dugong Population

Herds of dugong, a largely tropical marine megaherbivore, are known to undertake long-distance movements, sequentially overgrazing seagrass meadows in their path. Given their drastic declines in many regions, it is unclear whether at lower densities, their grazing is less intense, reducing their need to travel between meadows. We studied the effect of the feeding behaviour of a small dugong population in the Andaman and Nicobar archipelago, India to understand how small isolated populations graze seagrasses. In the seven years of our observation, all recorded dugongs travelled either solitarily or in pairs, and their use of seagrasses was limited to 8 meadows, some of which were persistently grazed. These meadows were relatively large, contiguous and dominated by short-lived seagrasses species. Dugongs consumed approximately 15% of meadow primary production, but there was a large variation (3–40% of total meadow production) in consumption patterns between meadows. The impact of herbivory was relatively high, with shoot densities c. 50% higher inside herbivore exclosures than in areas exposed to repeated grazing. Our results indicate that dugongs in the study area repeatedly graze the same meadows probably because the proportion of primary production consumed reduces shoot density to levels that are still above values that can trigger meadow abandonment. This ability of seagrasses to cope perhaps explains the long-term site fidelity shown by individual dugongs in these meadows. The fact that seagrass meadows in the archipelago are able to support dugong foraging requirements allows us to clearly identify locations where this remnant population persists, and where urgent management efforts can be directed.     

Cattle grazing and conservation of a meadow-dependent amphibian species in the Sierra Nevada

World-wide population declines have sharpened concern for amphibian conservation on working landscapes. Across the Sierra Nevada''s national forest lands, where almost half of native amphibian species are considered at risk, permitted livestock grazing is a notably controversial agricultural activity. Cattle (Bos taurus) grazing is thought to degrade the quality, and thus reduce occupancy, of meadow breeding habitat for amphibian species of concern such as the endemic Yosemite toad (Anaxyrus [ = Bufo] canorus). However, there is currently little quantitative information correlating cattle grazing intensity, meadow breeding habitat quality, and toad use of meadow habitat. We surveyed biotic and abiotic factors influencing cattle utilization and toad occupancy across 24 Sierra Nevada meadows to establish these correlations and inform conservation planning efforts. We utilized both traditional regression models and Bayesian structural equation modeling to investigate potential drivers of meadow habitat use by cattle and Yosemite toads. Cattle use was negatively related to meadow wetness, while toad occupancy was positively related. In mid and late season (mid July–mid September) grazing periods, cattle selected for higher forage quality diets associated with vegetation in relatively drier meadows, whereas toads were more prevalent in wetter meadows. Because cattle and toads largely occupied divergent zones along the moisture gradient, the potential for indirect or direct negative effects is likely minimized via a partitioning of the meadow habitat. During the early season, when habitat use overlap was highest, overall low grazing levels resulted in no detectable impacts on toad occupancy. Bayesian structural equation analyses supported the hypothesis that meadow hydrology influenced toad meadow occupancy, while cattle grazing intensity did not. These findings suggest cattle production and amphibian conservation can be compatible goals within this working landscape.     

Land-use,environment, and their impact on butterfly populations in a mountainous pastoral landscape: species richness and family-level abundance

Extensive grasslands are considered to be of high biodiversity value, but are under threat from intensification and abandonment. We studied butterfly species richness and abundance in 47 hay and grazing meadows in the Picos de Europa, northern Spain in 2004. Nine transects were walked around the perimeter of the meadows from the 1 June to 28 July with butterflies recorded to species or species-group. Land-use, abiotic, and sward variables were also recorded. Change in meadow extent was estimated by comparing a digital map of open meadows with a cadastral map with 1950s provenance. We found: A decrease in open area, mostly attributable to reduction in grazing meadows. 75 or more butterfly species with species richness principally, and positively, influenced by altitude and presence of scrub in the body of the meadow. Hay meadow management was a positive influence on richness of satyrids. When all butterflies were considered together, the only significant factor influencing abundance was Plantago lanceolata (−ve). For sub-groups of the butterfly community there was no consistent pattern, although P. lanceolata was identified as a (−ve) factor in relation to hesperiid, nymphalid, satyrid, and Viola-feeding fritillary groups. Several regression models included components that could be linked to abiotic influences (water, aspect, altitude) but many were indicative of abandonment or relaxation of management intensity (scrub, Pteridium aquilinum, Asphodelus albus), sward components, fragmentation (distance to nearest meadow, number of meadows within 100 m), and land use (hay management, summer grazing). The results are discussed in relation to changing socio-economics, including the potential impact of tourism, and the need for financial instruments to support extensive farming.