Species mobility and frequency dynamics in a Swiss limestone grassland

Arbuscular mycorrhiza is an ancient symbiosis between the majority of land plants and fungi
\nfrom the phylum Glomeromycota. Arbuscular mycorrhizal fungi (AMF) colonize plant roots
\nand contribute to the mineral nutrient uptake of the hosts in exchange for carbohydrates. AMF
\nspecies diversity and identity was reported to have a decisive influence on the composition
\nand productivity of natural plant communities. Only around 200 glomeromycotan species
\ndescribed so far were thought to colonize the majority of higher plant species and thus, their
\nhost specificity was thought to be very low.
\nIn this thesis, molecular methods were used to investigate ecological aspects of root
\ncolonizing AMF. The community composition of these fungi was analyzed in two plant
\nspecies-rich grasslands facing different environmental conditions and harboring different
\nplant communities. One site consisting of two meadows located close to each other was
\nsituated in the upper montane zone of the Swiss Alps. The other was located in the lowland in
\nFrance on the edge of the Jura mountains. The roots were analyzed using AMF-specific
\nnested PCR, RFLP screening and sequencing of rDNA small subunit and internal transcribed
\nspacer regions. AMF sequences were analyzed phylogenetically and used to define
\nmonophyletic sequence types.
\nOverall, 27 different AMF sequence types were detected in the root samples from both
\nfield sites. The overlap between the AMF communities in the alpine and lowland site was
\nrelatively small - they shared just six sequence types. These results indicate strong
\ngeographical differences in the AMF community composition, reflecting different
\nenvironmental conditions and plant species communities in each site.
\nThe question was adressed, whether different host plant species co-occurring in the same
\narea host distinct or similar AMF communities. Gentiana verna, G. acaulis and Trifolium spp.
\ngrowing in two alpine species-rich meadows harbored significantly different AMF
\ncommunities, whereas the differences between the two sites were negligible. These results
\nindicate that within a relatively small area with similar soil and climatic conditions, the host
\nplant species can have a major influence on the AMF communities within the roots. In these
\nalpine sites, there was also a focus on green plants from the family Gentianaceae. In contrast
\nto their mycoheterotrophic relatives, the green gentians did not show a high level of
\nspecificity towards AMF. The plants sampled harbored AMF communities comprising
\nmultiple phylotypes from different fungal lineages.
\nIn the lowland site – a calcareous grassland – different culturing methods and their
\ninfluence on the AMF community composition in the roots were adressed. Four plant species
\nwere sampled i) directly in the field, ii) in a bait plant bioassay conducted directly in that
\n
\ngrassland and iii) in a greenhouse trap experiment using soil and a transplanted whole plant
\nfrom that grassland as inoculum. The community composition in their roots was strongly
\ninfluenced by the experimental approach, with additional influence of cultivation duration,
\nsubstrate and host plant species in some experiments.
\nSome fungal phylotypes, e.g. Glomus mosseae and several members of Glomus group B,
\nappeared predominantly in the greenhouse experiment or in bait plants. These phylotypes can
\nbe considered r strategists, rapidly colonizing uncolonized ruderal habitats in early
\nsuccessional stages of the fungal community. Other phylotypes as Glomus badium and
\nGLOM-A16 were detected almost exclusively in roots sampled from plants naturally growing
\nin the grassland or from bait plants exposed in the field, indicating that they preferentially
\noccur in late successional stages of fungal communities and thus represent the K strategy. The
\nonly phylotype found with high frequency in all three experimental approaches as well as in
\nthe alpine site was GLOM A-1 (Glomus intraradices), which is assumed to be a generalist.
\nThese ecological strategies of different AMF species or phylotypes should be considered
\nin AMF experimental work. In greenhouse trap experiments it is difficult to establish a rootcolonizing
\nAMF community reflecting the diversity of these fungi in the field roots, because
\nfungal succession in such artificial systems may bias the results. However, the field bait plant
\napproach might be a convenient way to study the influence of different environmental factors
\non AMF community composition directly under the field conditions.
\nFinally, the co-existence of the Glomeromycota in the root samples with fungi from the
\nbasidiomycotan order Sebacinales was addressed. These fungi are widely distributed and
\nknown to form various types of presumable mycorrhizal associations of different morphology
\n(ecto-, ectendo-, orchid, ericoid, jungermannoid) with a broad range of host plant species.
\nHowever, their presence in plants forming arbuscular mycorrhiza has not been reported yet.
\nTherefore, the root samples originating from the two species-rich grasslands mentioned above
\nwere analyzed with Sebacinales-specific primers for the D1/D2 region of the nuclear 28S
\nrDNA subunit. Fungi from the order Sebacinales were present in the majority of the root
\nsamples from both sites, where they co-existed with the Glomeromycota. In agreement with
\nstudies targeting the Sebacinales in ericoid plants, the phylogenetic analysis of sebacinoid
\nsequences from our samples did not reveal any patterns according to their host plant species
\nor geographical origin.

Extensively managed pastures harbour rare and endangered species and have a decisive role in maintaining grassland biodiversity. Traditional herding of local robust cattle breeds is considered as a feasible tool for preserving these habitats. We studied the scale-dependent effects of grazing on the species richness and composition of three dry grassland types in the Great Hungarian Plain: Achilleo setaceae-Festucetum pseudovinae and Artemisio santonici-Festucetum pseudovinae alkaline grasslands, and Potentillo arenariae-Festucetum pseudovinae sand grassland. We asked the following questions: (1) Does extensive grazing have a scale-dependent effect on plant species richness of alkaline and sand grasslands? (2) How does grazing affect the proportion of specialists, generalists and weeds in the three grassland types? We sampled ten sites of each grassland type, including five extensively grazed and five non-grazed sites (altogether we had 30 sites). We used a series of nested plots each consisting of 10 plots from the size of 0.01 m² to 16 m². We revealed that grazing has contrasting effects in the three grassland types, and had a considerable effect on their species richness even at small scales. In both alkaline grassland types, total species richness was overall higher in grazed plots but it increased in a similar manner for both ungrazed and grazed habitats across plot sizes. Small-scale heterogeneity likely due to the uneven distribution of grazing, trampling and defecation together with mitigated rate of competition allowed more species to co-exist even at small scales in grazed alkaline grasslands. Grazing increased the richness of specialists, but likely due to the salt stress, establishment of weeds was hampered. Open gaps formed by trampling likely supported the establishment of several specialist species such as Plantago tenuiflora and Puccinellia limosa which are typical to open alkali grasslands. Contrary, in sand grasslands, we did not detect any effect of grazing on total species richness, likely due to the adverse effect of grazing on the species richness of specialists and weeds. In contrast with the former findings we detected significantly higher species richness in 0.01 m² and 0.0625 m² plots in the grazed sand grasslands, but found no differences at larger scales. Whilst species richness of specialists was significantly decreased, richness of weeds was increased by grazing. Decrease in the specialist species richness was likely due to the lack of their evolutionary adaptation to grazing. Degradation caused by grazing and trampling together with the propagule pressure from the neighbouring anthropo-genic habitats resulted in an increased richness of weeds in the grazed sites.

Nutrient-poor, dry calcareous grasslands in Central Europe harbour an extraordinary high diversity of plants and invertebrates. Consequently, they are of high conservation value. However, changes in agriculture (intensification or abandonment) have resulted in a dramatic reduction of semi-natural grasslands in the twentieth century. Today, dry grasslands are among the most endangered habitats. Furthermore, these grasslands are frequently fragmented and surrounded by forest or intensively cultivated agricultural areas. Semi-natural grasslands are fragile because their maintenance depends on traditional farming techniques. In order to avoid any loss of species by inappropriate land use, it is important to assess the responses of threatened species to particular types of grassland management. Although different types of present and past pasture management are known to affect the species richness and composition of plant communities, knowledge of the effects on invertebrates is limited. In particular, no studies exist on the influence of different types of pasture management on animals with limited mobility, such as gastropods. In the present thesis, I examined the effects of different pasture management practices on the snail community in dry, nutrient-poor grasslands of the Swiss Jura mountains, where extensive grazing with low stocking rate and without use of fertilizers is a traditional form of grassland management. I assessed the snail communities in extensive pastures grazed by horses, cattle or sheep, in cattle pastures with different management intensity and in extensive pastures with different management history in the last 55 years. Furthermore, gastropod species richness and abundance were examined in transects running from extensive pastures through gradual or abrupt forest edges into the forest interior. Grazing by different livestock species did not affect the species richness, abundance and species composition of land snails. However, independent of livestock species, snail species richness, abundance and number of red-listed species decreased with increasing grazing intensity. Furthermore, cattle pastures without fertilizer application and with low grazing intensity harboured more snail species and more threatened snails than pastures with annual addition of fertilizer and higher grazing intensity. Management intensity had also a negative influence on individual snail species (Cochlicopa lubricella, Truncatellina cylindrica, Vitrina pellucida, Helicella itala and Helix pomatia). Former changes in pasture use for a period of 10–40 years altered the present-day snail fauna. Past shrub cover had a negative effect on the total number of snail species and individuals, the number of open-land species and individuals and the number of red-listed individuals. Former use of fertilizer and higher grazing intensity reduced red-listed species and individuals and altered the snail community. The grassland snail communities of the pastures changed distinctly to forest communities at the first bushes or trees of edges towards forest interior irrespective of the type of forest edge. In pastures, at a distance of 10 m from gradual forest edges, more open-land snail species were found than at the corresponding distance from abrupt forest edges. Furthermore, ecotones of gradual forest edges harboured more open-land individuals than those of abrupt forest edges. For the conservation of grassland land snail communities, it does not matter whether pastures are stocked with horses, cattle or sheep, provided the grazing intensity is low. To preserve the threatened snail species in dry, nutrient-poor grasslands, a network of pastures should be managed without fertilization and grazing intensity should not exceed 180 LU.ha-1.d (product of livestock units per hectare and grazing days). Furthermore, to recover the typical grassland snail community in shrub cleared pastures or former fertilized pastures, the connection between intact pastures and grasslands under restoration should be improved by creating and maintaining new semi-natural areas and by exchanging livestock among these areas during the grazing season. Since shadowing of trees and alterations of the microclimate close to the forest edge may reduce the actual size of small grassland fragments, encroaching shrubs should be regularly removed and gradual forest edges created and maintained.

<i>Koeleria macrantha</i> (Ledeb.) Schultes (<i>K. alpigena</i> Domin, <i>K. cristata</i> (L.) Pers. pro parte, <i>K. gracilis</i> Pers., <i>K. albescens</i> auct. non DC.)

Floristic characteristics, syntaxonomy and synecology of grasslands of the order Brometalia erecti on calcareous massifs of central-southern Tuscany are reported. Multivariate analysis was used to compare 64 phytosociological releves made in the years 1997, 2000 and 2001. These pastures occur in areas of the temperate oceanic region, with upper hill to montane thermotype and lower humid to lower hyperhumid ombrotype, in serial contact with woods of Ostrya carpinifolia Scop. and with beech woods on summits. The plant communities surveyed were clasified in the following assciations: i) Cerastio etrusci-Brometum erecti ass. nova ( Phleo-Bromion Biondi & Blasi ex Biondi & al. 1995), identified for serie grasslands on moderate to steep slopes with basic lithosoils in the hill and lower montane belts; it has two variants related to soil chemical and physical characters: comparison with similar vegetation of other Apeninne areas confirms the western connotation and autonomous nature of these communities; ii) Trifolio incarnate-Brometum erecti Oberdorfer & Hofman 1967 ( Bromion W. Koch 1926), known from the Ligurian Apennine downwards; in the area studied it shows a new “Antiapenninic” subassociation named phleetosum ambigui that includes: a mesophilous variant with Arrhenatherum elatius , related to flat or north-exposed stations in the mountain belt; linked to mature soils with high moisture all year, rich in transgressive species of the class Molinio-Arrhenatheretea Tuxen 1937: a subnitrophilous variant with Carlina corymbosa , related to grazing and exclusive to soils wiht high clay component: a transition variant towards xerophilous grasslands. The study confirms the presence of the alliance Phleo-Bromion in Tuscany as an isolated appendage with northern outposts of xerocalcicolous communities widespread in the central-southern Apennine: a similarity with vegetation of northern Tyrrhenian sectors was also observed.

Wheat dwarf virus (WDV, genus Mastrevirus, family Geminiviridae) has a wide host range among Poaceae (Vacke, 1961). Grass species such as Briza media, Poa pratensis, Poa compressa, Bothriochloa ischaemum, Brachypodium pinnatum, Anthoxanthum odoratum, Agrostis capillaries, Phleum pretense, Dactylis glomerata, Lolium perenne, Trisetum flavescens, Cynosurus cristatus, Deschampsia cespitosa, Alopecurus pratensis, Arrhenatherum elatius, Poa trivialis, Apera spica-venti, Elymus caninus, Festuca arundinacea, Bromus inermis, Elytrigia repens and Echinochloa crus-galli were tested for the evaluation of the host range of two WDV strains: WDV-W and WDV-B. Three seedlings of each grass species were exposed to adults of viruliferous leafhopper vector Psammotetix alienus which were removed from the plants after three weeks. Subsequently, non- viruliferous P. alienus were left for acquisition feeding on the infected grass species for seven days, and were then transferred to healthy wheat and barley plants. The leafhoppers from the grasses inoculated by the WDV-W and WDV-B were transferred to wheat and barley plants, respectively. Samples from grasses and cereals (wheat and barley) were collected 30 and 70 days post inoculation, respectively, for WDV detection by DAS-ELISA (Sediag, France). WDV was detected in two A. spica-venti and C. cristatus plants inoculated by each of the WDV strains and in one L. perenne plant inoculated by WDV-W, as well as in wheat and barley plants. The rest of the grass species remained virus-free. Hence, our results confirm two earlier reported WDV hosts, i.e L. perenne (Vacke, 1971) and A. spica-venti (Vacke and Cibulka, 1999) and identify C. cristenus as a new WDV host. To the best of our knowledge this is the first report of C. cristanus as a host and potential reservoir of WDV in agroecosystems.

Modern agriculture has severely impacted the variety of life on earth. Agricultural expansion has cleared >50% of natural habitats on agriculturally usable land, while agricultural intensification has reduced the abundance and diversity of wildlife in farmed areas. Agri-environment schemes (AESs) offer opportunities to restore habitats for wildlife in farmed landscapes across Europe and elsewhere. This could help to (1) reverse declines in species of conservation concern and (2) provide “ecosystem services”, such as pollination, which contribute to human wellbeing. AES interventions have led to increases in the abundance and diversity of wildlife. However, despite the scale of public investment in AESs, the size and significance of those increases are often unclear. Furthermore, the outcomes of AES interventions vary depending on features of the surrounding landscape, especially semi-natural habitat. Research to date has directed the allocation of AES interventions in a broad sense, for example towards landscapes with <20% coverage of semi-natural habitat. Still, there is a lack of specific advice about how and where to restore habitat on farmland to maximise benefits for priority insect species. I present two field studies of the abundance and species richness of night-flying Lepidoptera (moths) in the UK, aiming to develop advice for land managers implementing AESs. Focussing on moths in three distinct habitat specialism groups, I looked at how the benefits of two types of AES interventions were affected by the coverage of semi-natural calcareous grassland (CG) nearby. In the first field study I investigated the benefits of AES interventions that create wide grass margins on the edges of arable fields. I found that grass margins significantly increased the abundance of grassland generalist moths. Furthermore, grass margins benefitted CG-associated moths if there were large areas of CG habitat nearby. Therefore, spatial targeting of AES interventions towards semi-natural habitat has the potential to improve outcomes for biodiversity. In the second field study I investigated the benefits of AES interventions that restore arable fields to species-rich grassland. Restored grassland fields were similar to semi-natural CG in terms of moth abundance and species richness. Furthermore, CG moths were more abundant on restored grassland where CG indicator wildflowers were established. Grassland restoration is a particularly successful AES intervention, especially if the plant community is enhanced to support priority insect species. Finally, I present the first individual-based model to test how the benefits of AES interventions depend on distance from source populations on semi-natural habitat. By simulating larval and adult life-stages of hypothetical insect species, my model provided a set of mechanisms that help to explain my empirical field observations. Ultimately, this thesis presents two of the most robust field studies on the interaction between AES interventions and the landscape context. By interpreting these field studies in light of a supporting model, I produce clear advice for land managers interested in the conservation of moths and the other species with which they coexist.

هدف از انجام این تحقیق تعیین ارزش غذایی هفت گونه از علف‌های هرز موجود در مزارع یونجه شامل: تلخه، بومادران و ریش قوش از خانواده کاسنی، یونجه و شبدرشیرین از خانواده بقولات و دم روباهی، علف پشمکی و علف باغ از خانواده گندمیان بود. نمونه‌برداری از گونه‌های مورد مطالعه در مرحله برداشت یونجه از مزرعه (10% گلدهی مزرعه) صورت گرفت. نمونه‌های برداشت شده در مزرعه به مدت 72 ساعت هوا خشک شده و برای انجام آزمایشات مورد استفاده قرار گرفت. ترکیبات شیمیایی، تخمیرپذیری و تجزیه‌پذیری نمونه‌ها با روش آزمایشگاهی تعیین شد. نتایج نشان داد که در بین گونه‌های مورد مطالعه از نظر ترکیبات شیمیایی تفاوت‌های معنی‌داری وجود داشت. یونجه با 3/14و دم‌روباهی با 4/8 درصد بیشترین و کمترین مقدار پروتئین خام را در بین علوفه‌های مورد آزمایش داشتند. بیشترین و کمترین میزان دیواره سلولی مربوط به دم روباهی و شبدرشیرین به ترتیب با 7/58 و 8/33 درصد بود. ریش قوش و تلخه به ترتیب با 8/28 و 5/19 درصد بیشترین و کمترین میزان دیواره سلولی منهای همی سلولز را در بین گونه‌های مورد مطالعه داشتند. با مقایسه میزان گاز تولیدی حاصل از تخمیر علف‌های هرز و یونجه در 96 ساعت پس از انکوباسیون، یونجه و علف پشمکی به ترتیب با 7/249 و 4/166 میلی‌لیتر به ازای هر گرم ماده خشک، بیشترین و کمترین میزان گاز تولیدی را به خود اختصاص دادند. در بین علوفه‌های مورد آزمایش بیشترین مقدار قابلیت هضم ماده آلی و اسیدهای چرب کوتاه زنجیر مربوط به یونجه و شبدرشیرین بود. ناپدید شدن ماده خشک برای شبدر شیرین در ساعات مختلف انکوباسیون بیشتر از بقیه گونه‌ها بود. علف پشمکی کمترین میزان ناپدید شدن را در بین گونه‌های مورد مطالعه داشت. شبدر شیرین و علف پشمکی با 6/32 و 2/23 درصد به ترتیب بیشترین و کمترین مقدار بخش سریع تجزیه‌پذیر ماده خشک را در بین علوفه‌ها داشتند. بخش با پتانسیل تجزیه‌پذیری کم و نرخ ناپدید شدن ماده خشک برای شبدر شیرین بیشتر از بقیه علوفه‌ها به جز یونجه بود. نتیجه کلی اینکه تفاوت بین ترکیبات شیمیایی، پتانسیل تولید گاز و تجزیه‌پذیری یونجه در مقایسه با علف‌های هرز بایستی در تنظیم جیره‌های غذایی نشخوارکنندگان مدنظر قرار گیرد اما آنچه مسلم است ارزش غذایی یونجه با توجه به نتایج به‌دست آمده قابل مقایسه با علف‌های هرز نمی‌باشد

Effects of grassland management on plants and invertebrates in Transylvania, Romania : a threat to local biodiversity hotspots

The conservation of biodiversity and natural resources relies to a large extent on the establishment of&#13;\nprotected areas. However, protected areas often fail to meet the objectives that lead to their establishment,&#13;\ndue to poor control over the manifold, legal and illegal human activities within protected areas,&#13;\ninsufficient knowledge about system characteristics, in particular with respect to disturbance regimes,&#13;\nand due to inappropriate management strategies and means of implementation.&#13;\nThe study investigates the responses of large herbivores to anthropogenic disturbances in Queen&#13;\nElizabeth National Park (QENP), Uganda. Unique features of QENP are high human population densities&#13;\nwithin and outside the park and a high degree of habitat fragmentation, resulting from natural (topography,&#13;\nlakes, channel) and anthropogenic (villages, roads, cattle pastures) factors. Outstanding&#13;\ndisturbances are man-made fires that frequently devastate large parts of the park. Fire frequency and&#13;\nseverity have increased over the last decades, leading to widespread and long-lasting loss of herbivore&#13;\nfeeding grounds.&#13;\nThe study is based on the assumption that the present fire regime, in combination with other anthropogenic&#13;\ndisturbances adversely affects the population development of the abundant large grazers in&#13;\nQENP under the local geo-ecological conditions. The main goals of this study are (1) to establish spatial&#13;\nand temporal habitat utilisation patterns of buffalo (Syncerus caffer), Uganda kob (Kobus kob thomasi)&#13;\nand hippopotamus (Hippopotamus amphibius) in relation to the prevailing fire regime and other&#13;\nanthropogenic disturbances, and (2) to provide baseline data for the elaboration of a fire management&#13;\nplan.&#13;\nThe study area is dominated by grassland in the central parts and bush-land with variable densities of&#13;\nbushes towards the water. Most of the study area is surrounded by water. Point surveys were conducted&#13;\nto estimate the distribution and abundance of the focal species, using Distance sampling. Environmental&#13;\nand anthropogenic factors were quantified by distances from each observation point using a&#13;\nGeographic Information System (GIS). All geo-referenced data were subject to multiple regression&#13;\nanalyses. Regression models for several stages of vegetation development before and after burning&#13;\nwere used to evaluate the spatial and temporal relationship between different disturbance factors and&#13;\nlarge herbivore abundance.&#13;\nThe effects of increasingly frequent fires over the last decades in the study area are the spread of fire&#13;\nclimax plant species such as Acacia sieberiana and shrubs of Acacia hockii, the spread of Imperata&#13;\ncylindrica, a widely indigestible grass species, and species-poor overgrazed grasslands in the main&#13;\ndistribution area of Uganda kob.&#13;\nThe distribution of Uganda kob is generally restricted to open grasslands and near to water in the&#13;\nNorth and East of the study area. Their movements in postfire-periods largely depend on the locality of&#13;\nburnt areas. Fresh pasture after burns is highly attractive to Uganda kob in all stages of postfire-development.&#13;\nHowever, adult males can suffer from food shortage after burns due to their strong attachment to their mating grounds (leks). Uganda kob does not show significant avoidance with regard to&#13;\nhuman activities, villages and roads. They are mostly affected by the decrease of suitable pasture in&#13;\nparts of the study area due to the encroachment of Imperata cylindrica. The data collected show that&#13;\ndensity of Uganda kob has significantly reduced in the western part of the study area where they were&#13;\nwidely distributed two decades ago. In addition, the combination of frequent fires and heavy grazing&#13;\nafter burns led to a loss of high quality grass species in their main distribution areas.&#13;\nThe distribution patterns of buffalo are characterised by an accumulation of large herds in the central&#13;\ngrasslands of the study area, while smaller herds occupy bush-land closer to the water. In postfireperiods&#13;\nbuffaloes prefer tall grass savanna in the southern part of the study area. They utilise postfire&#13;\npasture in burnt areas only in advanced stages of vegetation development. Buffaloes are affected by&#13;\nall quantified anthropogenic disturbances. They clearly avoid the vicinity of villages. The main road&#13;\nthrough the park restricts the movements of buffalo herds. Adverse effects of the habitat fragmentation&#13;\nbecome evident when home ranges of buffalo herds are burnt to a large extent. One of the outstanding&#13;\nthreats to buffalo is, however, competition with life-stock. Over the last decades buffaloes have&#13;\nnearly disappeared in areas with live-stock occupancy. Furthermore, inter-specific competition is probable&#13;\nbetween buffalo and hippopotamus in their feeding grounds along the water in postfire-periods.&#13;\nHippopotamuses are still abundant in large numbers in the study area. At present, they seem not to be&#13;\naffected by anthropogenic disturbances, apart from poaching.&#13;\nThe equilibrium of population sizes of the mega-herbivores hippopotamus and elephant (Loxodonta&#13;\nafricana) is important for maintaining the savanna structure in the study area, and in consequence for&#13;\nthe viability of other herbivores. Since elephants are not abundant in high numbers, the spread of&#13;\nbushes is one of the aspects to be monitored with respect to habitat availability (open grasslands) for&#13;\nother large herbivores. Appropriate fire management strategies could regulate the grassland-bushland&#13;\nmosaic in the study area.&#13;\nFire management is a tool to avoid adverse and amplify advantageous effects of fire on the habitats of&#13;\nherbivores. Recommendations for fire management in terms of controlled burning and protection from&#13;\nfires are given on the base of habitat classification that specifies temporal, spatial and functional aspects&#13;\nof the habitat use of large herbivores in time and space. The dynamic interrelations of anthropogenic&#13;\nand natural factors described may additionally contribute to adaptive strategies for the protection&#13;\nof wildlife in QENP.

The large ground‐dwelling bush cricket Decucus verrucivorus is widespread in continental Europe, but declining at the northern edge of its range This paper defines the species' habitat requirements in northern Europe by describing the distribution of each of the seven nymphal instars and adults in relation to vegetation structure within a chalk grassland in southern England First instars were strongly associated with short, sparse turf, reflecting the oviposition behaviour of females Subsequent early instars were also found in short, open turf, but at the fifth moult a distinct shift in distribution to dense grass tussocks occurred Late instars and adults were strongly associated with these structures, probably to avoid vertebrate predators Mean temperatures within tussocks were lower than in short turf, but these highly mobile stages actively thermoregulate by basking on the sides of tussocks In contrast, areas of short turf may be crucial for the development of the smaller and less mobile early instars and eggs It is concluded that a fine mosaic of closely‐grazed turf, dense tussocks and intermediate structures must be created and/or maintained at the species northern‐most sites, if its present distribution is not to contract

A loosely tufted perennial with short rhizomes from which arise vegetative shoots. Culms 15-60 (-100) cm high, slender, erect, 2-3-noded, solitary, smooth. Leaves with dull glaucous to mid-green adaxial and abaxial surfaces, hairless; blades usually 4-20 (-28) cm long, 2-4 (-7) mm wide, with minute acroscopic teeth on the margins, with a slender boat-shaped tip; ribs numerous, closely packed, less obvious on the abaxial surface; sheaths smooth, entire, soon splitting, dark reddish-brown at base; ligules up to 1.5 mm long, membranous, blunt with irregular margins. Culm leaves 3 or 4, uppermost with long sheaths. Panicles 410 (-18) cm long, lax, roughly pyramidal, with up to 20 branches, and up to 60 spikelets, sparsely divided, spreading, with scabrous hair-like pedicels 5-20 (-50) mm long and slightly thickened below the spikelets. Spikelets 4-7 mm long and wide, loosely scattered and drooping, broadly elliptic to broadly ovate, laterally compressed, generally purplish-brown, usually breaking up at maturity beneath the lemmas but many spikelets remaining undispersed on the branches and shed from the panicle intact, 4-9 (-12)-flowered. Glumes slightly unequal, deeply concave, hooded at the apex, boat-shaped, 2.5-3.5 mm long, with 3-5 veins, firmly membranous, dull-purple with white and shiny margins. Lemmas 3.7-4.1 mm, strongly cordate at the base, bluntly keeled in the lower half, closely overlapping, rounded on the back, with 7-9 veins, variegated purple and green, with hyaline margin. Paleas flat, thin, almost as long as the lemma, with two keels, narrowly winged. Lodicules 2, linear-lanceolate, acute. Grain enclosed within the papery lemma and palea, c. 2 mm long, rounded on the back, flattened on the front; mean oven-dry weight 0.53 mg. The root system is a dense mat of whitish fibrous roots. The primary roots are up to 1 mm in diameter and are largely unbranched, but there is a dense network of branching secondary roots. The root mass is fairly vertical with an average root length of c. 40 cm. The species produces pale brown rhizomes up to 13 cm long and 1.5 mm in diameter. Native. Subspecies media occurs throughout the range; subspecies elatior (Sibth. & Sm.) Rohlena occurs in south-east Europe.

Question: Do water gradients produce patterns of responses to stress and competition similar to those induced by nutrient gradients? Location: French Alps. Methods: We established a split-plot design in a calcareous grassland, with watering and fertilization as main plot treatments and competition as subplot treatment. We followed individual and competitive responses of transplants of the three potential dominant grass species: Bromus erectus, Brachypodium rupestre and Arrhenatherum elatius, in all plots during two growing seasons. Changes in natural relative abundances of the three grass species were also monitored. Results: The growth and the relative abundance of A. elatius were primarily stimulated by nutrient addition and those of B. rupestre by water addition, whereas B. erectus decreased in abundance and had a very low flexibility with enhanced resource supply. Competition intensity increased for all species with both watering and fertilization and the ranking in competitive responses did not change with treatments: A. elatius > B. rupestre > B. erectus. Conclusions: Patterns of dominance were efficiently explained by stress tolerance abilities and competitive responses for dry and poor sites, and wet and rich sites for B. erectus and A. elatius respectively, whereas competitive responses were poor predictors of dominance for B. rupestre in wet and nutrient-poor sites. Further studies are needed to assess the potential role of other processes, such as increasing competitive effect on light with increasing age as well as interference, to explain the dominance of this conservative competitor type of species in wet and nutrient-poor sites.

Question:Do water gradients produce patterns of responses to stress and competition similar to those induced by nutrient gradients?Location:French Alps.Methods:We established a split‐plot design in a calcareous grassland, with watering and fertilization as main plot treatments and competition as subplot treatment. We followed individual and competitive responses of transplants of the three potential dominant grass species: Bromus erectus, Brachypodium rupestre and Arrhenatherum elatius, in all plots during two growing seasons. Changes in natural relative abundances of the three grass species were also monitored.Results:The growth and the relative abundance of A. elatius were primarily stimulated by nutrient addition and those of B. rupestre by water addition, whereas B. erectus decreased in abundance and had a very low flexibility with enhanced resource supply. Competition intensity increased for all species with both watering and fertilization and the ranking in competitive responses did not change with treatments: A. elatius &gt; B. rupestre &gt; B. erectus.Conclusions:Patterns of dominance were efficiently explained by stress tolerance abilities and competitive responses for dry and poor sites, and wet and rich sites for B. erectus and A. elatius respectively, whereas competitive responses were poor predictors of dominance for B. rupestre in wet and nutrient‐poor sites. Further studies are needed to assess the potential role of other processes, such as increasing competitive effect on light with increasing age as well as interference, to explain the dominance of this conservative competitor type of species in wet and nutrient‐poor sites.

The physiological potential for acquisition of atmospheric ammonia (NH3) was investigated in three European meadow grasses (Arrhenatherum elatius, Bromus erectus and Brachypodium pinnatum) competing in chalk grasslands. Experiments were carried out with plants cultivated for about three months on a soil–sand mixture at high root nitrogen supply or in nutrient solutions at low root nitrogen supply. Two different root nitrogen regimes were applied to the solution‐grown plants: 130 μmol NO3 plant−1 wk−1 (approx. 50 kg nitrogen ha−1 in three months); or 130 μmol NO3− plus 130 μmol NH4+ plant−1 wk−1. Each regime was combined with two levels of NH3 fumigation (0 and 70 nmol mol−1 air for 24 d). Uptake of gaseous NH3 in the shoots was investigated under controlled environmental conditions including NH3 concentrations ranging from 0 to 30 nmol mol−1 air. Concurrently, photosynthesis, glutamine synthetase activity, nitrogen allocation, biomass allocation and apoplastic cation composition were measured. For A. elatius, the influence of photorespiration on NH3 acquisition was also assessed. Independently of plant nitrogen status, ammonia compensation points in A. elatius and B. erectus plants were &lt;0.5 nmol mol−1. The total leaf conductance to NH3 absorption remained constant at increasing NH3 concentrations, showing that the capacity for assimilation was unaltered. Whereas internal factors in the leaves did not cause differences in the potential for NH3 acquisition between the species, other factors of NH3 acquisition were quite different: B. erectus had higher stomatal conductance and, thus, higher NH3 uptake rates per unit leaf area compared to A. elatius and B. pinnatum; higher stomatal conductances of B. erectus were to a large extent offset by a lower leaf area per plant, resulting from a lower growth rate and thicker leaves than in the two other species. The rate of photorespiration in Arrhenatherum constituted at least 15% of the net photosynthetic rate. Surprisingly, suppression of photorespiration indicated that NH3 uptake was supported by photorespiration. Bromus responded to fumigation with 70 nmol NH3 mol−1 air for 24 d by lowering the root∶shoot ratio and increasing the nitrogen concentration in the stem dry matter. The total leaf conductance to NH3 uptake decreased in all three species upon exposure to NH3, while the stomatal conductance was unaffected. The NH3 exposure caused lower apoplastic concentrations of H+, Mg2+ and Ca2+ in A. elatius and B. erectus.