Grazing Grassland Research Articles

Soil C mineralization and temperature sensitivity in alpine grasslands of the Qinghai-Xizang Plateau

Aims Currently, the temperature sensitivity of soil carbon (C) mineralization and the factors that control it are the focus of studies on soil C cycle and global climate change. The main objectives of this study were to: (1) in- vestigate the effects of temperature and land-use (fenced grassland vs. grazing grassland) on soil C mineralization and its temperature sensitivity (Q10) in the grasslands of Qinghai-Xizang Plateau and (2) determine the relation- ships of the rate of soil C mineralization with soil properties (e.g. soil organic carbon content (SOC), soil total ni- trogen content (STN)). Methods Eleven pairs of plots (fenced sites vs. grazing sites) were selected along an east-west transect in northwest of Qinghai-Xizang Plateau. Soil samples were collected at a depth of 0-20 cm, to measure soil C min- eralization rates under a temperature gradient (i.e. 5, 10, 15, 20, and 25 °C) in laboratory. Data for soil C miner- alization rate on the 7th day and 56th day, respectively, were used to assess the short- and long-term effects. Important findings Soil C mineralization rates declined from east to west on fenced sites, but varied slightly on the grazing sites. Soil C mineralization rates increased significantly with increasing incubation temperature, and were strongly related to SOC and STN; higher the SOC and STN, greater the accumulative soil C mineralization. Q10 showed no apparent spatial pattern along the east-west transect, and was not susceptible to land-use with av- erage Q10 values of 1.83 and 1.86 on the fenced sites and the grazing sites, respectively. Moreover, Q10 was not correlated with either SOC or STN. Findings in this study provide new insights on the responses of soil C miner- alization and its temperature sensitivity to land-use change on the Qinghai-Xizang Plateau, contributing important information for evaluating soil C sequestration and its response to warming scenarios in this region.

Grassland Grazing Contracts and Degradation: Relationship and Mechanism

Is there some relation between the degradation and grazing institution? This paper attempts to find internal mechanism among the institution, herdsman behavior and degradation. The behavior of herdsman once was analyzed in private property of grassland, although once opposed. A grazing contract model under uncertainty was built, with which the herding behavior was checked. To analyze the relationship and mechanism between contracts characteristics and grassland degradation, the relation between and different risk preferences were studied under the decentralized equilibrium of the contract through setting the different parameters to show the basic characteristics of the grazing contract. We reach the following conclusions: the risk preferences of the type of pastoral are important to grassland degradation. The fact means the party to a contract is risk-neutral and will lead to overgrazation. Grassland degradation will arise in some situation expected utility maximization, even when both parties are risk averse. The conclusion is similar Elinor Ostrom’s points in 1990 that private property rights of grasslands may not the only, even not the best solution.

Sustainability of grassland-based beef production – Case studies of Danish suckler farms

The grazing of semi-natural grassland (SNG) is encouraged in Europe for the conservation of biodiversity, but little is known about the farming systems including SNG which farmers develop. The purpose of this study was to explore and evaluate at farm level the (1) technical results in terms of animal growth, feed use and carcass quality, (2) landscape biodiversity value, based on case study of ten Danish suckler beef farms with data recording over one year. Herd size varied from 5 to 213 suckler cows. The main conclusion was that an increasing proportion of SNG (up to 45% of net energy in a year diet at herd level) did not obviously imply low technical performances. However, when SNG was used as the entire feed to all animals all year long (over 80% of net energy in a year diet at herd level), performances were lower and meat quality did not fit the requirements of the meat industry, but were considered in alternative market chains. This last type of management (rustic breeds kept permanently on SNG) had the highest use of grassland (one suckler cow and her offspring for roughly every 3ha SNG) and thus the highest biodiversity conservation potential.

Conventional tillage increases soil microbial biomass and activity in the Loess Plateau, China

Land-use change can affect the quantity and quality of soil organic matter (SOM) as well as soil microbial biomass and activity. Land use in the Loess Plateau has undergone great changes in the past five decades. To understand the effects of these changes on soil chemical and biological properties in the Loess Plateau, we determined soil organic carbon (SOC), total nitrogen (TN), soil microbial biomass carbon (SMBC) and soil microbial biomass nitrogen (SMBN), and basal respiration in millet cropland (MC), grazed grassland (GG) and enclosed grassland (EG). Grazing exclusion led to an increase of SOC and TN. Compared with the MC, the two grasslands had higher SOC and TN values in the 0–10 cm layer, but lower values in the 20–30 cm layer. SMBC and SMBN values in the EG were intermediate between the MC and GG. Conversion of cropland to grassland increased soil basal respiration (SR) and metabolic quotient (qCO2), while grazing exclusion resulted in higher SR but lower qCO2. The study suggests that grassland enclosure could increase SOM as well as soil microbial biomass and activity, and conventional cropland might be the optimal land-use type to maintain soil chemical and biological properties in the Loess Plateau, China.

Root Characteristics of Perennial Warm-Season Grasslands Managed for Grazing and Biomass Production

Minirhizotrons were used to study root growth characteristics in recently established fields dominated by perennial C4-grasses that were managed either for cattle grazing or biomass production for bioenergy in Virginia, USA. Measurements over a 13-month period showed that grazing resulted in smaller total root volumes and root diameters. Under biomass management, root volume was 40% higher (49 vs. 35 mm3) and diameters were 20% larger (0.29 vs. 0.24 mm) compared to grazing. While total root length did not differ between grazed and biomass treatments, root distribution was shallower under grazed areas, with 50% of total root length in the top 7 cm of soil, compared to 41% in ungrazed exclosures. These changes (i.e., longer roots and greater root volume in the top 10 cm of soil under grazing but the reverse at 17–28 cm soil depths) were likely caused by a shift in plant species composition as grazing reduced C4 grass biomass and allowed invasion of annual unsown species. The data suggest that management of perennial C4 grasslands for either grazing or biomass production can affect root growth in different ways and this, in turn, may have implications for the subsequent carbon sequestration potential of these grasslands.

Grazed vegetation mosaics do not maximize arthropod diversity: Evidence from salt marshes

Light to moderate grazing in grasslands can create vegetation mosaics of short grazed vegetation and tall ungrazed vegetation. These mosaics have been proposed to maximize plant and animal species richness, yet experimental evidence, especially regarding arthropods is scarce. This study compares abundance, richness and species composition of arthropods in grazed mosaics to those of homogeneous short and tall vegetation.We sampled arthropods on three German coastal salt marshes where grazing with three densities (high, moderate and none) was installed in 1989 on previously intensively grazed plots. Stable vegetation mosaics had developed under moderate stocking densities. We collected spiders, beetles, bugs and moth larvae by suction sampling in a stratified random sampling design.Treatments had caused large differences in plant composition after 20years, which were reflected in the arthropod community. Most species showed a clear preference for either short or tall vegetation, but some species were most abundant in grazed mosaics. Arthropod richness and composition were similar in patches of short vegetation in moderately and highly stocked plots, while patches of tall vegetation were similar to ungrazed plots. Surprisingly, however, grazed mosaics were not richer in species than homogeneous tall vegetation, despite the co-occurrence of species from short, tall and mosaic vegetation.We conclude that, although arthropod richness of salt marshes is greatly enhanced when stocking density is decreased, this cannot substitute ungrazed marshes for conservation of arthropod diversity. However, long term cessation leads to the disappearance of several species, and therefore the possibilities of rotational grazing should be explored.

Effects of livestock grazing on the spatial heterogeneity of net soil nitrogen mineralization in three types of Mongolian grasslands

Small-scale soil heterogeneity relates to productivity and biodiversity and is crucial to understand. Soil heterogeneity could be affected by vegetation structure, and large mammal grazers could modify it through herbivory and excretion. The objective is to clarify the effects of livestock grazing on the small-scale (∼3 m) soil heterogeneity in three types of Mongolian grasslands. We sampled soils from inside (ungrazed) and outside (grazed) exclosures in three vegetation types: forest-steppe, shrub-steppe, and desert-steppe. We measured laboratory rates of soil net nitrogen (N) mineralization and net nitrification and geostatistically analyzed heterogeneity. Average rates of net N mineralization and net nitrification were lower at shrub-steppe and desert-steppe and were decreased by grazing. Semivariograms showed vegetation-induced heterogeneity in ungrazed plots, except for net nitrification at forest-steppe. We found linear change with distance under dense and uniform vegetation at forest-steppe, 1.3 m patch under patchy vegetation at shrub-steppe, and linear change, but with much smaller semivariance, under sparse and poor vegetation at desert-steppe. At forest-steppe, grazing randomized the spatial patterns of net N mineralization and net nitrification. At shrub-steppe and desert-steppe, grazing greatly decreased the semivariances of net N mineralization and net nitrification as well as their averages, and the soil heterogeneity was virtually disappeared. Grazing in Mongolian grasslands homogenized the spatial patterns of net N mineralization and net nitrification, irrespective of their original spatial patterns determined by the differences in vegetation structure.

Effects of long-term management practices on grassland plant assemblages in Mediterranean cork oak silvo-pastoral systems

The assessment of the effects of long-term management practices is relevant in understanding the current patterns of plant assemblages in semi-natural ecosystems. We hypothesized that the variety of management practices across different farming systems under the same ecological conditions directly and indirectly shapes these patterns via the long-term changes induced in soil features. The aims of this paper were to evaluate the influence of two sets of variables describing long-term management practices and soil features on plant assemblages and their importance in the context of Mediterranean silvo-pastoral systems. The analysis of variance revealed that richness and grazing value were not affected at all by grazing livestock species and soil tillage frequency and that they both showed relatively high absolute values for the specific context under study. Trifolium subterraneum was a key species in contributing to grassland grazing value and habitat biodiversity. The Canonical Correspondence Analysis highlighted the influence of management practices and soil features on plant assemblage composition, which was significantly affected by grazing livestock species and stocking rate and by soil pH and K content. The Redundancy Analysis showed that soil pH and related features were in turn affected by stocking rate, supporting our hypothesis that management practices influenced plant assemblage composition directly and indirectly via their long-term effects on soil features. The results also highlighted that a systemic analytical perspective applied at a grazing system scale can be effective in addressing sustainable grassland management issues in Mediterranean silvo-pastoral systems.

Experimental investigation on soil carbon, nitrogen, and their components under grazing and livestock exclusion in steppe and desert steppe grasslands, Northwestern China

Livestock grazing is one of the main causes for the change of soil organic carbon (SOC) and total nitrogen (TN) in the arid and semi-arid parts in northern China. This paper examined the SOC, TN, and their components of the local steppe and desert steppe, considering continuous grazing and 4-year livestock exclusion, respectively. In steppe where livestock is excluded, both SOC and TN in the topsoil (0–0.20 m) are found to remain unchanged; however, significant growths are found in microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), particulate organic carbon (POC), and particulate organic nitrogen (PON). On the contrary, both POC and PON progressively decrease at the continuous grazing sites, attributed to the reduction of the mass proportions of soil particulate fraction in the top 0.10 m soil. In the desert steppe where grazing is excluded, the SOC, TN, and their components of the topsoil increase. However, at the continuous grazing sites, POC and PON in the 0.10 m topsoil are reduced, caused by the decrease of C and N content in soil particulate fraction. Besides, microbial quotients were lower in the continuous grazing sites in the two grasslands. It is also found that both MBC and POC are more sensitive to human-induced activities than SOC, and thus could serve as earlier indicators of the soil-fertility variation caused by short-period grazing management.

Earthworms, spiders and bees as indicators of habitat quality and management in a low-input farming region—A whole farm approach

The benefits of low input farming on biodiversity and ecosystem services are already well-established, however most of these studies focus only on the focal field scales. We aimed to study whether these benefits exist at the whole farm scale, to find the main environmental driving effects on biodiversity at the whole farm scale in farms of different grassland grazing intensity, applying three well-known species diversity indicator groups of different ecological traits.Edaphic (earthworms), epigeic (spiders) and flying (bees) taxa were sampled in each identified habitat type within 18 low-input farms in Central Hungary, 2010. The number of habitat types, the number of grassland plots, the cumulative area of grasslands and habitat type had an effect on the species richness and abundance of spiders, while grassland grazing intensity influenced the species richness of bees. Both bees and spiders were sensitive to vegetation and weather conditions, resulting in more bees on flower-rich farms and those having higher temperature; and more spiders on farms with more heterogeneous vegetation structure and in low-wind areas. Relatively few earthworms were found in the whole study, and their abundance was not influenced by any of the farm composition and management variables.We conclude that local field management (grazing intensity of grassland patches) can have a farm scale effect, detectable on species diversity indicators that have high dispersal ability and strong connection to grasslands as important foraging sites (bees). However, other farmland biota (spiders) is also strongly determined by farmland composition and habitat diversity, therefore the maintenance of a mosaic within-farm habitat structure is strongly recommended. The application of earthworms as farmland composition or management indicators is strongly restricted because of their special needs of soil conditions.

Effects of Land-Use Change on Water in Andean Páramo Grassland Soils

Mountain environments, including the Andean páramo grasslands of Ecuador, are important water source areas. They are often sites of programs and policies intended to achieve multiple management objectives, such as carbon sequestration, biological conservation, and water resource protection; yet such environments are often data poor. This creates challenges for programs that compensate landowners for protecting ecosystem services and uncertainty regarding which land uses are compatible. For example, does afforestation for carbon sequestration complement or hinder efforts to protect water resources in Andean páramos? We compared characteristics of high-elevation soil profiles at sites in two Ecuadorian páramo study areas and measured soil–water properties to assess whether changes in land use affected the soil hydrology. Using a space-for-time substitution, we compared soils in plantations of pines and Polylepis racemosa in grasslands with different grazing and burning regimes. Methods included soil description in soil pits; soil moisture measurement in soil pits and across surface transects; tracer studies of soil–water movement; and laboratory determination of bulk density, particle size, and humic acid composition. Of the land uses examined, only afforestation significantly affected soil moisture, whereas soil properties did not differ among grassland burning and grazing regimes. The results suggest that afforestation of páramos hinders the production of water and they underscore the need for further investigation to inform the trade-offs needed in managing páramo landscapes to support multiple ecosystem services.

围封对内蒙古大针茅草地土壤碳矿化及其激发效应的影响

土壤呼吸及其控制机理是全球变化研究的重点之一,其中土壤呼吸的温度敏感性和激发效应是近年来的研究热点。以长期围封的大针茅草地(Fenced grassland, FG)和自由放牧草地(Grazing grassland, GG)为对象,通过不同温度(5、10、15、20、25℃和30℃)和添加混合凋落物的室内培养途径,探讨了长期围封对草地碳矿化(或土壤微生物呼吸)的温度敏感性和激发效应的影响。实验结果表明:在培养42 d内,长期围封的大针茅草地的土壤碳矿化累积量高于自由放牧草地;土壤碳矿化量随温度的升高而升高,围封对大针茅草地土壤碳矿化的温度敏感性的影响不显著,<em>Q</em>₁₀值介于1.1-1.9之间。添加混合凋落物使土壤碳矿化表现出了明显的激发效应,且自由放牧草地的激发效应高于长期封育草地;在培养的前7 d,土壤激发效应随着培养温度升高而增强,激发效应最高值达6.38;但在整个培养期(42 d)土壤激发效应15℃为最大。从长远角度看,中间温度更有利于土壤激发效应以及土壤碳矿化。在相同的有机物质输入状况下,长期围封大针茅草地的激发效应更低,可能是大针茅草地在长期围封状况下仍然具有碳固持效应的重要机制之一。;In recent decades, the carbon (C) cycle and soil respiration of terrestrial ecosystems have been become hot topics for the global climate change, and research focused on the temperature sensitivity and priming effects of soil microbial respiration (or soil C mineralization) has increased rapidly since 2000. In this study, we focused on long-term fenced <em>Stipa grandis</em> grassland (FG) and grazing <em>Stipa grandis</em> grassland (GG) in Inner Mongolia, China, investigating the impact of land-use change on the temperature sensitivity and the priming effects of soil microbial respiration by incubating soils in the laboratory under a temperature gradient (5, 10, 15, 20, 25 and 30℃) and with substrate addition (mixed litter). The incubation experiment was continued for 6 weeks, and the rates of soil C mineralization were measured throughout using our newly developed equipment. The results showed that the amount of soil C mineralization was higher in GG than that in FG duration the 6-weeks incubation. The rates of soil C mineralization increased significantly with increasing incubation temperature for both GG and FG (temperature coefficient (<em>Q</em>₁₀) values ranged from 1.1 to 1.9), however, the <em>Q</em>₁₀ values for GG and FG were not significantly different. After mixed-litter addition, the rates of soil C mineralization not only in GG but also in FG increased significantly, and showed the apparent priming effects of C mineralization. Compared with long-term fenced grassland (FG), grazing grassland (GG) had higher priming effects, which even after only 7 d were 6.38 times higher. Moreover, the priming effects increased with increasing incubation temperature in the first week, although these effects were the highest at 15℃ duration the 42 d of incubation. These findings suggest that, on a longer time scale, medium temperatures should promote soil C mineralization. On the whole, long-term grazing exclusion depressed the priming effect of soil microbial respiration and resulted in less C emission under the same mixed litter input. This is probably one of the mechanisms underlying the capacity of long-term fenced grasslands to sequester CO₂ in Inner Mongolia.

Effects of grazing and fencing on carbon and nitrogen reserves in plants and soils of alpine meadow in the three headwater resource regions

Knowledge about carbon and nitrogen in plants and soils and response to fence and graze in alpine ecosystems is still rudimentary because of extremely geographic situation. The purpose of this study was to compare the difference among carbon, nitrogen concentration, and content of unit area and dynamics of above- and below-ground biomass, soil organic carbon and total nitrogen between fencing and grazing alpine meadow. The results showed that total carbon and C: N radio in the aboveground tissue were significantly higher in fenced and ungrazing grassland (FU) than those in free grazing grassland (FG). In addition, the order of total carbon and nitrogen concentration of aboveground tissue of different function groups were not identical between them; The total carbon storage (TCS) per unit of aboveground tissue, roots and 0–30 cm soil layer increased after being fenced for 5 years from free grazing grassland (9255.17 g/m2) to fenced and ungrazing grassland (12637.10 g/m2) by 26.79%. The corresponding total nitrogen storage (TNS) increased by 751.42 g/m2. Furthermore over 95% TCS (TNS) come from 0–30 cm soil layer. However there were no significant differences between fenced and ungrazing grasslands of 10 years and 5 years. Therefore fenced to exclude grazing by Tibetan sheep and yaks was an alternative approach to sequester C to the soil in alpine meadow systems.

The biodiversity and stability of alpine meadow plant communities in relation to altitude gradient in three headwater resource regions

Kobresia pygmaea meadow community diversities in relation to altitude gradients (4200, 4300, 4400, 4450) on free grazing grassland was studied in the range of Chenduo county, Yushu prefecture, Qinghai province. Species richness and diversity index of vegetations in the four altitudes were comparatively analyzed. The results showed that the shape of species richness responsive curves to altitude gradient is “Bell-shape”. There were the same 11 common species in the four communities. The relative abundance of K. pygmaea decreased along increasing altitude. Moreover, the fuzzy membership functions were used to calculate the degree of stability, showing medium altitude > high altitude > low altitude, which suggested that grass land vegetation in low altitude of the sampling site had lower diversity, and the grade of species vulnerability risks may be decided with the help of the degree of stability. Key words : Alpine meadow, Yangtze, Yellow and Yalu Tsangpo river source region, altitude gradient, species diversity, membership functions.

Converting oak woodland or savanna to vineyards may stress groundwater supply in summer

Water resources are important to land-use planning, especially in regions where converting native oak woodlands or savannas to wine grape vineyards may affect the amount of water available for restoring salmon runs. Research has shown that woodland conversion to grasslands (for possible rangeland grazing) leads to greater and more sustained stream flow and groundwater recharge; however, little information is available about woodland conversion to vineyards. To inform resource managers and planners, we developed a water balance model for soil and applied it to vineyards, native oak woodlands and annual grasslands to evaluate their relative use of groundwater. We applied the model to Sonoma County, using climate data from 1999 to 2011, and determined that oak tree canopy coverage of 40% to 60% results in annual groundwater extraction equivalent to that of an established irrigated vineyard. However, vineyard groundwater use far exceeded that of oak woodlands in late summer to early fall, which could further stress already affected groundwater resources. We also evaluated the prediction sensitivity of the model to key parameters associated with rain levels, soil water-holding capacity and irrigation management.

Hemicryptophytes plant species as indicator of grassland state in semi-arid region: Case study of W Biosphere Reserve and its surroundings area in Benin (West Africa)

In semi-arid region managers are facing rapid degradation of grassland. There is a need to determine indicators to be used to detect early change occurring in the grassland for their sustainable management. Thereof, in this study, we explored the reliability of the use of hemicryptophytes as indicator of grassland state in semi-arid region within W Biosphere Reserve and surrounding areas (Benin). Plots of 10 m X 10 m were installed along a land use gradient (from communal lands to the protected area via the buffer zone) in three vegetation types for plant biomass harvesting and hemicryptophytes traits measurement. The hemicryptophyte density, biovolume, tussock size, contact frequency, contribution to total plant biomass and grassland grazing value were assessed and compared between land uses. Findings showed that hemicryptopyte traits were significantly different with the land use type. Hemicryptophyte biovolume and hemicryptophyte contribution were strongly correlated, respectively, with total biomass production and grazing value. The study highlights the relevance of hemicryptophyte as indicators of grassland state that could be used by grassland managers for grassland monitoring, restoration and sustainable use.Keywords: Grassland monitoring, hemicryptophyte traits, indicators, land use

Species of Drosophila (Diptera: Drosophilidae) attracted to dung and carrion baited pitfall traps in the Uruguayan Eastern Serranías

This study investigates the species richness and abundance of Drosophila Fallen, 1823 attracted to dung and carrion baited pitfall traps in natural areas with heterogeneous habitats at the Sierra de Minas, Eastern Serranias, southeastern Uruguay. Collecting was carried out on a monthly basis (May 2002 through April 2003). Drosophilids accounted for 0.84% (n = 131) and 3.61% (n = 158) of the Diptera collected from dung (n = 15,630) and carrion (n = 4,382) pitfall traps, respectively. A total of 12 species were identified, 11 of which belong to the subgenus Drosophila (the richest) and one to the subgenus Sophophora Sturtevant, 1939. Over 90% of the Drosophila specimens collected belong to five species of the subgenus Drosophila, namely D. gaucha Jaeger & Salzano, 1953, D. immigrans Sturtevant, 1921, D. mediovittata Frota-Pessoa, 1954, D. aff. nappae Vilela, Valente & Basso-da-Silva, 2004, and D. ornatifrons Duda, 1927. Drosophila cardini Sturtevant, 1916 is recorded for the first time from Uruguay. Drosophila abundance and species richness in the four habitats sampled in the Uruguayan Eastern Serranias, namely woodlands sierra, riparian forest, pine plantation and grazing grassland, were considered to be a function of habitat conservation. Diversity indices were low in all habitats. Different habitats supported particular coprophilous and necrophilous Drosophila species. The woodland sierra represents the most preserved habitat, and contributed with the highest species richness observed. Drosophila ornatifrons was the dominant species, with a restricted habitat distribution. On the other hand, grazed grassland, an environment modified by livestock management, had the lowest species richness: only a few specimens of D. repleta Wollaston, 1858. Regarding species composition, significant differences were found in some pairwise comparisons of groups of Drosophila species that included D. ornatifrons. Fly attraction to dung can be exploited as an alternative and/or complementary collecting method in ecological studies of Drosophila assemblages in natural areas.

Ensemble modelling of climate change risks and opportunities for managed grasslands in France

The Pasture Simulation model (PaSim) was used to simulate agronomic and environmental services at 12 grassland sites in France, comparing near past climate conditions (1970–1999) and projections for near (2020–2049) and far future (2070–2099). Modelled climate change impacts were assessed using statistical and threshold-based analysis on managed (intensive, extensive) grasslands (permanent, sown), comparing shallow and deep soils, and for an ensemble of emission scenarios, climate models, and downscaling/initialization methods.Results show a significant drift of all sites towards more arid climates by the end of the century. Significant reductions in annual water drainage and herbage protein content are projected, together with new opportunities for annual and seasonal herbage production, in spring and winter especially. Simulated future conditions also show an increased interannual and seasonal variability of production. Contrary to expectations, current natural conditions reflecting large water availability are not expected to reduce future risks of negative climate change impacts on grassland systems. Notably, milk production from aftermath grazing of permanent grasslands established on deep soils at Mirecourt (humid site) is estimated to fall down below one-third of the current median value in four out of 30 years (∼13%) for 2070–2099, whereas similar shortfalls were not observed with the baseline climate.Balancing risks and opportunities, permanent extensive grasslands can be viewed as a trade-off between the continuity of grassland service provision and the mitigation of greenhouse gas emissions.

The effect of plant spatial pattern within a patch on foraging selectivity of grazing sheep

Plant spatial pattern has been considered as one of the most important factors influencing forage selection of herbivores in natural grasslands. Previous work has emphasized the effects of spatial distribution patterns of food resource at the scale of whole plant communities. Our objective was to explore whether changes in spatial patterns of food within a patchy site affected forage selection of sheep within and among patches. We conducted a manipulative experiment using three native plant species of different palatability and abundance to artificially create three different quality patches in each treatment. We compared the effects of aggregated and randomly dispersed patterns, within high, medium, and low quality patches respectively, on sheep forage selection. Effects of plant spatial patterns within a patch on sheep forage selection of the patch itself strongly depended on the patch quality. For high quality patches, random dispersion of food resources significantly decreased sheep consumption of the palatable plant within the patch. This effect was reversed in low quality patches, and was not significant in medium quality patches. Changes in plant spatial patterns within high quality patches greatly influenced sheep forage selection of other patches. However, changes in plant spatial patterns within medium or low quality patches significantly influenced foraging responses of sheep only for high quality patches. We therefore conclude that high quality resource sites are the most influential and susceptible foraging areas. Our results highlight the importance of high quality resource sites when considering grazing grassland conservation and management.

Action versus Result-Oriented Schemes in a Grassland Agroecosystem: A Dynamic Modelling Approach

Effects of agri-environment schemes (AES) on biodiversity remain controversial. While most AES are action-oriented, result-oriented and habitat-oriented schemes have recently been proposed as a solution to improve AES efficiency. The objective of this study was to compare action-oriented, habitat-oriented and result-oriented schemes in terms of ecological and productive performance as well as in terms of management flexibility. We developed a dynamic modelling approach based on the viable control framework to carry out a long term assessment of the three schemes in a grassland agroecosystem. The model explicitly links grazed grassland dynamics to bird population dynamics. It is applied to lapwing conservation in wet grasslands in France. We ran the model to assess the three AES scenarios. The model revealed the grazing strategies respecting ecological and productive constraints specific to each scheme. Grazing strategies were assessed by both their ecological and productive performance. The viable control approach made it possible to obtain the whole set of viable grazing strategies and therefore to quantify the management flexibility of the grassland agroecosystem. Our results showed that habitat and result-oriented scenarios led to much higher ecological performance than the action-oriented one. Differences in both ecological and productive performance between the habitat and result-oriented scenarios were limited. Flexibility of the grassland agroecosystem in the result-oriented scenario was much higher than in that of habitat-oriented scenario. Our model confirms the higher flexibility as well as the better ecological and productive performance of result-oriented schemes. A larger use of result-oriented schemes in conservation may also allow farmers to adapt their management to local conditions and to climatic variations.