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Butterfly and grasshopper diversity patterns in humid Mediterranean grasslands: The roles of disturbance and environmental factors
Abstract and Figures
The present paper studies butterfly, grasshopper and vascular plant communities in ten seasonally flooded grasslands with different anthropogenic disturbance regimes (NW Greece). Disturbance intensity was assessed on the basis of disturbance frequency and type (grazing, mowing, trampling, constructions). The distribution patterns of butterflies are regulated by humidity and elevation (Redundancy Analysis). Elevation, flower-heads abundance, low disturbance intensity and plant species richness predict grasshopper species richness well, while the latter together with humidity predict plant species richness (Generalized Linear Models). Chorthippus lacustris, a critically endangered endemic grasshopper species, is positively associated with humid microhabitats with high flower-heads abundance. An indicator value procedure reveals four butterfly species as being typical species for habitats with a pronounced character of hedgerows and tree lines. Conservation management of grassland butterflies should focus on the maintenance of the humid character of the humid grasslands as well as on the maintenance of hedgerows and tree lines. The reduction of human-induced disturbance towards occasional grazing and mowing seems to benefit both butterfly and grasshopper communities. Finally, we suggest the use of grasshoppers as surrogates for vascular plants and vice versa, given their congruent species richness patterns.
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... Grasshopper species richness has been positively correlated with sward height variability (Kruess and Tscharntke, 2002;Fumy et al., 2020), and there are some welldocumented surveys of grasshopper species relying on a mosaic of short and tall patches at different stages of their developmental cycle (Cherril and Brown, 1992;Willott, 1997). Grasshopper abundance is also usually higher in tall and extensively managed swards (WallisDeVries et al., 2007;Marini et al., 2008Marini et al., , 2009Dumont et al., 2009;Kati et al., 2012;Fleurance et al., 2016). ...
... Finally, Walcher et al. (2019) found a significant positive correlation between Orthoptera and vascular plant species richness in semi-natural grasslands of the Austrian Alps. Additionally, Kati et al. (2012) concluded that low disturbance intensity, as well as plant species richness, predict grasshopper species richness in humid Mediterranean grasslands. They even suggested the use of grasshoppers as surrogates for vascular plants and vice-versa, given their congruent species richness patterns. ...
... Also all outliers for grasshopper abundance came from a highly diverse grassland community located on shallow soil in the Italian survey. This grassland hosted many grasshoppers because most species require open and relatively dry and warm grasslands (Marini et al., 2008), conditions which were confirmed by observations made in other Mediterranean grasslands (Kati et al., 2012). The response of grasshopper assemblages to environmental change was recently shown to differ among vegetation communities (Fumy et al., 2020), and it thus becomes obvious that building our indicators from only a limited number of grassland management classes can decrease the precision of their habitat value assessment. ...
We propose a set of indicators to evaluate how grazing by livestock and grassland management can help preserve biodiversity in the insect communities of grassland ecosystems. These indicators can be calculated for any grassland for which management and botanical composition are known, and they do not require advanced knowledge on conservation biology and entomology. Based on the scientific literature and expert interviews, each indicator combines pressure (i.e., 16 management classes) and state variables (i.e., sward botanical composition and several of the plant functional characteristics) to assess the effects on butterfly, bumblebee, and grasshopper abundance and species richness. Each indicator was based on a multicriteria decision tree with fuzzy partitioning to account for uncertainty in the threshold values between different alternatives. The output validation of indicators was performed by comparing decision tree output with standardized measurements from 10 surveys across France, Germany, Switzerland, Wales, and Italy. The prediction of grassland suitability for butterflies was more accurate for butterfly species richness (P < 0.05) than for butterfly abundance (P = 0.10), as even under standardized transect counts, recorders will observe disproportionately more individuals when it is sunny and warm. The sensitivity of the butterfly species richness indicator was then tested using an independent dataset of 395 French grasslands. There were significant differences in predicted species richness (χ215 = 121.16; P < 0.05) among the 16 management classes, and they were ranked consistently in spite of very parsimonious assumptions in the decision tree. The prediction of grassland suitability was good for bumblebee abundance (P < 0.05) and species richness (P < 0.01). This prediction was also successful for grasshopper abundance (P < 0.05) and species richness (P = 0.05), all outliers coming from a highly diverse grassland community located on shallow soil in the Italian survey. This set of indicators can thus provide a cost-effective evaluation of temperate grassland suitability as habitat for three insect taxa. These indicators have more relevance than general insect species richness, and their application does not require any entomological skill. The indicators can help stakeholders to make adequate decisions for insect conservation in grassland ecosystems, but do not have direct applicability to higher conservation value taxa or species.
... Previous studies have documented how environmental factors such as temperature, rainfall and humidity can affect butterfly species richness (Hadley 1994;Stefanescu, Herrando, and Pá ramo 2004;Kati et al. 2012). To determine the influence of abiotic factors on butterfly species richness, we collected daily climate data [maximum temperature ( C), minimum temperature ( C), mean relative humidity (%) and total rainfall (mm)] from the Department of Environment, Bangladesh, which is about 5-8 km away from our study sites. ...
... Although we did not formally quantify disturbance, butterflies seemed to prefer less disturbed habitats within the green spaces, aligned with evidence that disturbance can reduce species richness in urban habitats (Biswas and Mallik 2010;Kati et al. 2012;Jain, Lim, and Webb 2017). During our field survey, we found that high butterfly species richness seemed to coincide with areas less frequently visited by people in both the National Botanical Garden and Ramna Park (pers. ...
Cities currently harbour more than half of the world's human population and continued urban expansion replaces natural landscapes and increases habitat fragmentation. The impacts of urbanisation on biodiversity have been extensively studied in some parts of the world, but there is limited information from South Asia, despite the rapid expansion of cities in the region. Here, we present the results of monthly surveys of butterflies in three urban parks in Dhaka city, Bangladesh, over a 3-year period (January 2014 to December 2016). We recorded 45% (137 of the 305 species) of the country's butterfly richness, and 40% of the species detected are listed as nationally threatened. However, butterfly species richness declined rapidly in the three study areas over the 3-year period, and the decline appeared to be more severe among threatened species. We developed linear mixed effect models to assess the relationship between climatic variables and butterfly species richness. Overall, species richness was positively associated with maximum temperature and negatively with mean relative humidity and saturation deficit. Our results demonstrate the importance of urban green spaces for nationally threatened butterflies. With rapidly declining urban green spaces in Dhaka and other South Asian cities, we are likely to lose refuges for threatened fauna. There is an urgent need to understand urban biodiversity dynamics in the region, and for proactive management of urban green spaces to protect butterflies in South Asia.
... Lepidoptera is a group that has been used to estimate diversity (Gerlach, et al. 2013), despite that they are also describing management in human modified ecosystems. Lepidopteran in open Greek grasslands were influenced by the frequency of grazing and soil moisture retention (Kati, Zografou, Tzirkalli, Chitos, & Willemse, 2012). Salty marshes in Germany also showed reduced species richness with higher sheep densities, showing that moths were more sensitive that plants (grass) when showing grassland deterioration (Rickert, et al., 2012). ...
... After determination, all individuals were released. For the classification of the Orthoptera species we used five-grade ordinal abundance classes adapted to Kati et al. (2012): no individuals, 1-3 individuals, 4-10 individuals, 11-50 individuals, and > 50 individuals per plot and survey (Table 1). ...
The native bracken fern ( Pteridium aquilinum (L.) Kuhn) has become increasingly invasive in abandoned or undergrazed Alpine grasslands. Bracken stands are generally assumed to be poor in species, but there is still very little information about the impact on the fauna. We recorded Orthoptera communities of 24 sample plots with varying bracken cover. Compared to plots with only sparse or medium bracken cover, species richness was highly significantly lower in densely overgrown plots, while the former two did not differ markedly. Multivariate ordination analyses revealed gradients with unequal orthopteran communities, showing distinct patterns of bracken cover clustering. Based on indicator values, 13 of 23 Orthoptera species turned out to be significantly or marginally significantly associated with a single bracken cover stratum or a combination of two strata, whereby all nine Red List species were primarily restricted to sparse or medium bracken cover. However, some generalist species were found to favor denser bracken stands, such as Tettigonia viridissima , contributing to the local Orthoptera beta diversity. Our data suggest that ongoing rotational sheep grazing with temporary paddocks is regarded as the most preferable management system. However, selected parts of the study area, which have only sparse vegetation and no pressure of bracken or scrub overgrowth, are recommended to be alternately left ungrazed for a few years to allow for the coexistence of different successional stages. Low-intensity bracken control measures, situationally by mowing or uprooting, are considered appropriate and should be pursued.
Implications for insect conservation
Even though most specialized and rare Orthoptera species in Western Europe tend to prefer sparsely vegetated areas, subareas with medium to even dense vegetation cover might promote certain generalist species, leading to a higher local species richness.
... Clearly, the engineering effects of livestock on insect herbivore behavior and populations have the potential to shape grassland ecosystems, but this will require scaling up from our smallscale, short-term microcosm experiment to larger temporal and spatial scales relevant to domestic grazer management and policy. This may help ecologists and rangeland scientists think of livestock not just as an instrument of anthropogenic disturbance (e.g., Kati et al. 2012;Lightfoot 2018), but as community members in a human-modified ecosystem whose ecological interactions are as diverse and context-dependent as those of native grazers, with potential conservation value through their ecosystem engineering effects (Steffen-Dewenter and Tscharntke 2002;Woodcock et al. 2005). ...
Introduced ecosystem engineers are expected to have extensive ecological impacts on a broad range of resident biota by altering the physical–chemical structure of ecosystems. Livestock that are potentially important introduced ecosystem engineers in grassland systems could create and/or modify habitats for native plant-dwelling insects. Yet, there is little knowledge of how insects respond to engineering effects of introduced livestock. To bridge this gap, we tested how domestic sheep affects the behavior and abundance of a native grasshopper Euchorthippus unicolor at both low (11.8 ± 0.4 plant species per plot) and high (19.8 ± 0.5 plant species per plot) diversity sites. Results found grasshoppers shifted their resting and feeding locations from the upper to the intermediate or low layers of vegetation, and fed on more plants species following livestock engineering effects. In the low plant diversity habitats, grazing caused grasshoppers to increase switching frequency, spend more time searching for host plants, and reduce time spent feeding, but had opposite effects on all the three behaviors in the high-diversity habitats. Moreover, grazing engineering effects on behavioral changes of grasshoppers were potentially related to their abundance. Overall, this study highlights native insect species’ behavior and abundance in responses to introduced ecological engineers, and suggests that ecosystem engineers of non-native species have strong and important impacts extending beyond their often most obvious and frequently documented direct ecological effects.
... low vs. high elevation sites), orthopteran communities became also more dissimilar in terms of species composition. These results are consistent with other studies reporting detrimental effects of colder temperatures on orthopteran diversity along elevational gradients (Descombes et al. 2017;Kati et al. 2012). Most orthopteran species are thermophilic and low temperatures limit all their key physiological processes, thus determining a reduced performance and fitness (Schmitz et al. 2016;Willott and Hassall 1998). ...
In mountains, current land-use changes are altering plant communities of semi-natural grasslands with potential cascading effects on associated herbivores. Besides vegetation changes, temperature is also a key driver of insect diversity, and in the European Alps is predicted to increase by 0.25 °C per decade. Understanding herbivore responses to temperature and plant composition changes in mountain environments is of increasing importance. Our study aims at investigating the response to temperature and plant diversity and composition of two key herbivore groups (orthopterans and leafhoppers) belonging to contrasting feeding guilds (chewers vs. sap-feeders). We hypothesized that orthopteran diversity would be driven by temperature while leafhoppers by plant community composition. We selected 15 dry calcareous grasslands ranging from 100 to 1330 m a.s.l. along two independent gradients of plant diversity and temperature. We sampled orthopteran and leafhopper species richness and abundance by sweep-netting. Consistent with their low feeding specialisation, orthopteran species richness and community composition were only driven by temperature. By contrast, leafhopper species richness was not affected by temperature nor by plant diversity but leafhopper community composition was strongly influenced by plant species composition. This response can be explained by the higher host feeding specialisation of many leafhopper species. Species rarity and mobility did not change the response of the diversity of both groups, but orthopteran abundance increased with temperature only for highly mobile species. Altogether, our results suggest that future responses of grassland herbivores to vegetation changes and temperature warming are highly variable and depend on the feeding strategy and specialisation of the focal herbivore group.
Implications for insect conservation
Leafhoppers emerged to be particularly sensitive to potential management or climate-induced change in vegetation composition, while orthopterans are expected to respond directly to temperature warming due to their relaxed association with plant community diversity and composition.
... It is also important for species of conservation concern such as the endangered C. lacustris (Kati et al. 2006). Elevation, flower-heads abundance, low disturbance intensity, and plant species richness predict grasshopper species richness well, while the latter together with humidity predict plant species richness (Kati et al. 2012). A study on the species composition, diversity, abundance, and density of four rangelands types in China, showed that the greatest abundance of grasshoppers was found in mountain rangeland, while the lowest abundance of grasshoppers was caught in alpine shrublands (Sun et al. 2015). ...
Leksono AS, Yanuwiadi B, Afandhi A, Farhan M, Zairina A. 2020. The abundance and diversity of grasshopper communities in relation to elevation and land use in Malang, Indonesia. Biodiversitas 21: 5614-5620. Ecological factors include interactions of the community members with numerous biotic and abiotic factors such as temperature, humidity, precipitation, light intensity, and seasonality show an altitudinal gradient. Most grasshopper species play a role as herbivores and are a good source of protein for other animals such as amphibians, small reptiles, birds, and small mammals. This study aimed to analyze variations in the abundance, richness, and diversity of grasshopper species along an altitudinal gradient. This research was conducted in five locations in Malang District, East Java, Indonesia, namely Bantur, Sumber Pujung Lawang, Pujon, and Poncokusumo. Grasshopper sampling was carried out by the sweeping method using an insect net. Sweepings were carried out on four plots with each plot size of 2 x 10 m2. Sampling was conducted four times from June to August 2020. The data were analyzed using the Shannon Wiener index (diversity analysis) and the Bray-Curtis index. The differences between locations were tested by one-way analysis of variance. Land use was analyzed by ArcGIS, using Landsat imagery 8. The abundance of grasshoppers had a significant negative correlation with elevation. That correlation was positive to species richness and diversity of grasshoppers. That with species diversity was significant, while that with species richness was not significant. The greatest abundance of the grasshopper was found in the middle elevation in Lawang (19.39 ± 2.12). In contrast, the highest species richness and diversity were found in the highest elevation in Poncokusumo (richness = 15.75 ± 1.60 and H '= 2.58 ± 0.11). Land use variation was not significant on abundance, species, richness, and diversity of grasshoppers. Interestingly, the high similarity of the grasshopper compositions in low elevation habitats was detected, indicating that land use in the low land area was remarkable. The abundance of grasshopper had a significant positive correlation with temperature but negatively correlated with humidity. There was no significant correlation among species richness, species diversity with temperature and humidity.
... Delley, 2014) as several known factors were shown to negatively affect orthopterans. Human disturbance has been shown to affect insects (Kati et al., 2012), while an important factor for orthopteran mortality is mowing, as orthopterans are either killed through the mechanical process or exposed to predators due to low grass height (Arlettaz, 1996) or flee to unmown refuges, thereby decreasing orthopteran abundance on the meadow (Buri et al., 2016;Humbert et al., 2012). After regrowth of the vegetation, orthopteran abundance increased again without reaching the initial values. ...
A growing food demand and advanced agricultural techniques increasingly affect farmland ecosystems, threatening invertebrate populations with cascading effects along the food chain upon insectivorous vertebrates. Supporting farmland biodiversity thus optimally requires the delineation of species hotspots at multiple trophic levels to prioritize conservation management. The goal of this study was to investigate the links between grassland management intensity and orthopteran density at the field scale and to upscale this information to the landscape in order to guide management action at landscape scale. More specifically, we investigated the relationships between grassland management intensity, floral indicator species, and orthopteran abundance in grasslands with different land use in the SW Swiss Alps. Field vegetation surveys of indicator plant species were used to generate a management intensity proxy, to which field assessments of orthopterans were related. Orthopteran abundance showed a hump-shaped response to management intensity, with low values in intensified, nutrient-rich grasslands and in nutrient-poor, xeric grasslands, while it peaked in middle-intensity grasslands. Combined with remote-sensed data about grassland gross primary productivity, the above proxy was used to build landscape-wide, spatially explicit projections of the potential distribution of orthopteran-rich grasslands as possible foraging grounds for insectivorous vertebrates. This spatially explicit multitrophic approach enables the delineation of focal farmland areas in order to prioritize conservation action. © 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd
The current technical report presents the results of a research project in two Natura 2000 sites, namely the National Park of Oeta Mountain (GR2440004) and Tymphristos mountain (GR2430001). OITI project concerned the Orthoptera community of the two mountains and specifically their endemic and/or threatened species. It presents the objectives of the study, the methods and protocols used during fieldwork, and the research findings as follows: overview of the threats and pressures recorded in the study area, inventory of the recorded orthoptera fauna in the two protected areas, a thorough ecological overview of target species, presenting their conservation status (distribution, population status, habitat preferences , pressures and threats). The study suggests the inclusion of 11 important orthoptera species in the Standard Data Forms (SDFs) of the Natura 2000 sites, evaluates the ecological importance of the study area in terms of Orthoptera fauna conservation, and provides an evaluation of the pressures/threats that need to be addressed. It concludes to a conservation guideline relevant to (a) providing permissions for projects that cause land use change on target species habitats, such as renewable or tourist infrastructure, (b) livestock grazing management, (c) biomonitoring of target species, (d) Natura 2000 area expansion.
Grassland insects face some of the most severe declines in species diversity and total abundance, in part due to agriculture. Livestock grazing is the largest agricultural land use and can have both positive and negative effects on insect communities and populations. A global synthesis is needed to guide butterfly conservation and provide recommendations for scientists, managers, and other stakeholders seeking to use grazing as a tool for butterfly conservation. Here I review 115 studies that evaluate how cattle grazing affects butterfly communities and species. I discuss how various aspects of cattle grazing affect butterfly community and species responses. Thirty-five studies concluded cattle grazing has positive effects on butterflies, while 20 concluded cattle grazing has negative effects. Thirty-six were inconclusive or found no effect of grazing. Conclusions depended heavily on the management chosen as well as environmental and evolutionary factors. Eighty-five studies (74%) were located in Europe, providing a useful framework for the rest of the world, but also creating opportunities for further research.
Implications for practice
Low to moderate grazing intensity is the most beneficial grazing management strategy for butterflies. There is also potential for rotational grazing to provide benefits, but more research is needed. It is important to have variation in grazing management and other disturbance types in the landscape (mowing, prescribed fire, etc.) to accommodate differing habitat needs of butterfly species. Cattle grazing has potential as a land-sharing opportunity to promote grassland butterfly diversity in agroecosystems.
A long-standing objective of ecology has been to explain the basis for diversity patterns. Empirical evidence suggests that regional variation in richness of both animals and plants depends strongly on energy availability. The generality of the richness-energy hypothesis is limited by the paucity of analyses of invertebrates, which are much more diverse than the more thoroughly investigated vertebrate taxa. In this study, we consider two groups of North American Lepidoptera for which large-scale distribution data are available: the Papilionidae (swallowtail butterflies) and forest lepidopterans (moths based on the Canadian Forest Insect Survey). Energy, as measured by potential evapotranspiration (PET), statistically explains between 61 and 72% of the variability in the richness patterns of the Lepidoptera we have examined. It is the single best predictor of the richness of these groups, and the relationships have a very similar form to richness-PET relationships observed earlier in vertebrate taxa. After PET, Papilionidae richness is related to topographical heterogeneity. These patterns are true both within and among biomes. These results suggest that the richness-energy hypothesis applies generally to both vertebrates and insects in cold and temperate regions.
Pairwise comparisons between occupied and apparently suitable, yet unoccupied, Bacrocnema sites in the San Juan Mountains of southern Colorado indicated that occupied sites have a greater diversity of nectar source genera than unoccupied sites. This suggests a means of improving the efficiency of search efforts for additional populations of this butterfly. -Authors
The effect of drought on embryonic development and on hatching was studied in 13 European Tettigoniidae species. Drought can affect development in three different ways: (1) Embryonic development proceeds slower than if the eggs are in contact with water; (2) it stops (for final diapause) in an earlier embryonic stage; (3) it affects maintenance and termination of the initial embryonic diapause. In many Tettigoniidae species, the initial diapause is prolonged, and may last several years. Without draught stress, between 1 and 7 cold treatments in the laboratory, and with eggs of the Tettigonia-species between 1 and 6 winters in the field were necessary to enable all eggs to complete initial diapause. In Central European species, the number of eggs maintaining initial diapause significantly increased when the eggs had no contact with water at the time when they should recover from diapause. In contrast, termination of initial diapause in Tettigonia caudata from Greece, when the environment became favorable for growth again, was highest in that group of eggs that had lost most water in a preceding period of drought. The importance of the prolonged initial diapause for the survival of unpredictable adverse conditions is discussed.
This paper presents a new and simple method to find indicator species and species assemblages characterizing groups of sites. The novelty of our approach lies in the way we combine a species relative abundance with its relative frequency of occurrence in the various groups of sites. This index is maximum when all individuals of a species are found in a single group of sites and when the species occurs in all sites of that group; it is a symmetric indicator. The statistical significance of the species indicator values is evaluated using a randomization procedure. Contrary to TWINSPAN, our indicator index for a given species is independent of the other species relative abundances, and there is no need to use pseudospecies. The new method identifies indicator species for typologies of species releves obtained by any hierarchical or nonhierarchical classification procedure; its use is independent of the classification method. Because indicator species give ecological meaning to groups of sites, this method provides criteria to compare typologies, to identify where to stop dividing clusters into subsets, and to point out the main levels in a hierarchical classification of sites. Species can be grouped on the basis of their indicator values for each clustering level, the heterogeneous nature of species assemblages observed in any one site being well preserved. Such assemblages are usually a mixture of eurytopic (higher level) and stenotopic species (characteristic of lower level clusters). The species assemblage approach demonstrates the importance of the 'sampled patch size,' i.e., the diversity of sampled ecological combinations, when we compare the frequencies of core and Satellite species. A new way to present species-site tables, accounting for the hierarchical relationships among species, is proposed. A large data set of carabid beetle distributions in open habitats of Belgium is used as a case study to illustrate the new method.
We describe a new species of long-eared bat, genus Plecotus, from the island of Sardinia (Italy). The new species is clearly distinguishable from other European Plecotus species by its mitochondrial 16S rRNA gene (4.1–9.6% sequence divergence) as well as by a unique combination of morphological characters such as brownish colour of dorsal pelage, a relatively large thumb and thumb claw, an almost cylindrical form of the penis and the characteristic shape of the baculum. The most important morphological diagnostic character is a relatively long (≥ 18 mm) and wide (≥ 6 mm) tragus. The new species is currently known from three localities on Sardinia. In addition to the new species we discovered a lineage of P. auritus, which is substantially differentiated from continental P. auritus at subspecific level (1.2–2.7% of sequence divergence of the 16S rRNA gene). The existence of these two endemic bat taxa on Sardinia highlights the island's importance in the conservation of the European bat community.
Arachnid communities of alpine grassland, of screes and woodlands near the timberline and of the nival zone have been compared along a transect from the northern to the southern border of the Dolomites. The region is zoogeographically interesting because of differences of the ice cover during glaciation, which was less severe in the southern area. Along the whole transect spider communities in grasslands and at the timberline zone show approximately the same composition. Endemic species, e.g, Harpactea grisea (Canestrini 1868), Amaurobius ruffoi Thaler 1990, Coelotes mediocris Kulczynski 1887, Cybaeus intermedius Maurer 1992 and Eudasylobus ligusticus Roewer 1923 occur mostly on the southernmost station, which remained free of ice. Re-immigrants over short distance are scarce, e.g., Coelotes mediocris at Passo Rolle and Coelotes solitarius L. Koch 1868 in the Puez area. Endemic species were not found in the alpine grassland of the northern Dolomites, which suggests severe impact of glacial events on the local fauna. Central alpine species, i.e., Erigonella subelevata (L. Koch 1869), Metopobactrus nadigi Thaler 1976, Meioneta orites (Thorell 1875), Pardosa blanda (C.L. Koch 1833) and Pardosa mixta (Kulczynski 1887) are still present at the southernmost boundary of the Alps. Nunataks in the northern and central area of the Dolomites allowed speciation effects within the nival fauna: Lepthyphantes brunneri Thaler 1984, Lepthyphantes merretti Millidge 1974, Megabunus armatus (Kulczynski 1887). Further zoogeographically interesting records are Cryphoeca nivalis Schenkel 1919 and Xysticus bonneti Denis 1938.
The river marsh areas 'Niedervieland' and 'Ochtumniederung' in Bremen comprise about 3500 ha. They are characterised by extensive grassland-utilisation, high water levels and a dense ditch system. The grasshopper fauna is relatively species-poor with only 22 registered species. Some of the most abundant species are Chorthippus albomarginatus, Ch. biguttulus and Conocephalus dorsalis. From a nature conservation point areas most valuable for grasshoppers are wet fallows and wetland meadows accommodating Stetophyma grossum and Tetrix subulata, as well as sandy soils with records of species like Oedipoda caerulescens and Tetrix tenuicornis. The destruction of valuable grassland areas on about 760 ha required extensive compensation measures such as flooding of grassland, creation of ditches and banks or the development of sandy soils and wet fallows. Efficiency controls for 5 to 10 years showed an increase of numbers of species and individuals in nearly every investigation area. Tetrix subulata and Stetophyma grossum expanded in wet grassland. Comparing studies in surrounding grassland areas showed a general increase of grasshopper species and individuals. Chrysochraon dispar newly invaded the river marsh. Other grasshopper species like Chorthippus biguttulus, Tettigonia viridissima, Metrioptera roeseli or Ch. apricarius have extended their distribution area. This increase is obviously connected to climatic changes, having also affected other animal groups in Northern Germany: thermophilic animal species are presently extending their distribution areas. The results show that efficiency controls have to be conducted on the long term and that the results have to be compared to data from surrounding areas.
Farmland has undergone some of the most extensive changes of any biotope in Britain over the past 40 years. The post-war drive for agricultural self-sufficiency, augmented by improved mechanization and the introduction of synthetic agro-chemicals in the 1950s, has led to drastic intensification of agriculture in lowland Britain (Mellanby, 1981; Sly, 1981). In addition to the well-documented loss of large areas of both farmed and non-agricultural semi-natural habitats (Anon., 1984), the area and quality of smaller, interstitial areas of uncultivated land within the arable landscape has been decimated.