Sampling of insect communities is very challenging and for reliable interpretation of results the effects of different sampling protocols and data processing on the results need to be fully understood. We compared three different commonly used methods for sampling forest beetles, freely hanging flight-intercept (window) traps (FWT), flight-intercept traps attached to trunks (TWT) and pitfall traps placed in the ground (PFT), in Scots pine dominated boreal forests in eastern Finland. Using altogether 960 traps, forming 576 sub-samples, at 24 study sites, 59760 beetles belonging to 814 species were collected over a period of a month. All of the material was identified to species, with the exception of a few species pairs, to obtain representative data for analyses. Four partly overlapping groups were used in the analyses: (1) all, (2) saproxylic, (3) rare and (4) red-listed species. In terms of the number of species collected TWTs were the most effective for all species groups and the rarer species the species group composed of (groups 1-2-3-4) the larger were the differences between the trap types. In particular, the TWTs caught most red-listed species. However, when sample sizes were standardized FWTs and TWTs caught similar number of species of all species groups. PFTs caught fewer species of all species groups, whether the sample sizes were standardized or not. In boreal forests they seem to be unsuitable for sampling saproxylic, rare and red-listed species. However, the PFTs clearly sampled different parts of species assemblages than the window traps and can be considered as a supplementary method. The abundance distribution of saproxylic species was truncated lognormal in TWT and pooled material, whereas unclassified material failed to reveal lognormal distribution in all the trap types and pooled material. The results show that even in boreal forests sample sizes of at least thousands, preferably tens of thousands of individuals, collected by a high number of traps are needed for community level studies. Relevant ecological classification of material is also very important for reliable comparisons. Differences in the performance of trap types should be considered when designing a study, and in particular when evaluating the results.
One of the most important services provided by biodiversity is thought to be the biological control of pests in agricultural landscapes, including aphids on cereals. The food webs potentially contributing to biological control of aphids primarily consist of polyphagous predators, parasitoids and pathogens. The problems of aphid pests have increased greatly since the 1970-ies, possibly as an effect of agricultural intensification, which is thought to have reduced diversity and abundance of these predators and parasites and consequently their biocontrol potential. The main objective of this study was to test this by measuring this potential for biological control of aphids, and relate it to agricultural intensification and predator abundance. We selected 30 farms distributed along agricultural intensification gradients, based on the amount of fertilizers applied per hectare. Estimates of ground-living predator density were obtained using pitfall trapping over a one-week period. Traps were placed inside the cereal fields, 10 m from the margin, in 2 replicates per field. Predation risk due to ground-living predators (biocontrol potential) was estimated by monitoring removal of aphids glued to labels. This was done in the same fields, in the immediate vicinity of the traps, over a period of 2 days. The proportion of aphids eaten per unit time was the response variable. We present the correlations between intensity of agricultural exploitation, predator abundance and biocontrol potential. The outcomes are not straightforward in that intensification begets a reduction in predator density and biocontrol potential. We discuss the potential confounding issues that might have affected our results.
Wetland vegetation in the sub(alpine) zone of the West Carpathians (Poland, Slovakia) was studied with particular reference to the following questions: (i) What are the main types of (sub)alpine fen, bog and spring vegetation above the timberline in the West Carpathians? (ii) Which major environmental gradients are associated with the variation in floristic composition? (iii) What determines the α-diversity of bryophytes and vascular plants in the different vegetation types? Vegetation plots were sampled and direct measurements of certain environmental characteristics recorded. Cluster analysis was used to distinguish the vegetation types, DCA and CCA to reveal the main vegetation gradients and environmental factors, and general regression models to identify the factors determining the α-diversity. Classification at the level of 12 clusters was ecologically and syntaxonomically interpretable. Two associations not mentioned in the most recent vegetation survey of Slovakia were distinguished and the syntaxonomical positions of others revised. The synthesis of collected and published vegetation data for the two countries has modified the classification concept of (sub)alpine wetlands in the West Carpathians. Whereas pH predominantly determined floristic differences among classes, different factors governed the species composition within classes. While the diversity of the vegetation of springs (Montio-Cardaminetea) was mostly determined by water chemistry, altitude and geomorphology appeared to be more important within fens and bogs. The species richness of spring vegetation was more influenced by mineral richness than water pH and for bryophyte richness the slope inclination was also important. The species richness of fens and bogs increased with pH. It is concluded that the ecological gradients influencing the floristic composition and species richness of (sub)alpine wetlands are strongly habitat-dependent.
The altitudinal gradient in diversity of dung beetles (Scarabaeidae) was studied in a Mediterranean mountain chain located in Central Anatolia to (i) determine if there are altitudinal differences between the main taxonomic groups, (ii) describe the seasonal variations in these assemblages and (iii) assess whether closed habitats influence dung beetle diversity differentially at different altitudes. Beetles were collected throughout a year at 14 localities between 469 and 1810 m above sea level in three different types of habitats. Dung beetle assemblages at 400 to 1200 m did not vary greatly in species richness, abundance and biomass. However, they varied in composition, with the assemblages dominated by species of Scarabaeinae up to 900 m, whereas in the mid-mountain assemblages (from 900 m to 1600 m) the numbers of species of Aphodiinae was higher. The decline with increase in altitude in richness, abundance and biomass of both small and large species of Scarabaeinae up to 1500 m, together with the constancy of these parameters in the case of Aphodiinae, accounts for the changes in the composition from the lowland to mid-mountain localities. Unlike at other Mediterranean localities, the open/closed structure of the habitat only slightly influences these assemblages independently of altitude or season. The general seasonal pattern follows the classical Mediterranean bimodal pattern associated with summer drought, but the patterns are more complex when the seasonal responses of the different groups and at different localities are analysed separately. We propose that the interplay between local climatic conditions (mainly temperature) and evolutionary conserved species preferences accounts for both the current seasonal and altitudinal gradients and the changes in species composition in terms of Aphodiinae and Scarabaeinae.
Although it is well known that bats commonly forage in riparian areas, which provide water resources and insect concentrations, the role that the physical structure of riparian areas plays in influencing local bat communities is less certain. In 2000–2002, we used acoustic monitoring to determine bat species presence at 338 riparian sites in northwestern Georgia, USA. We used a 2-dimensional nonmetric multidimensional scaling (NMDS) ordination to assess how separations among species were partially associated with riparian conditions. Our NMDS analysis found some degree of habitat partitioning among bat species occurring in northwestern Georgia and was dictated in part by riparian condition. Myotis grisescens and M. septentrionalis were associated with low-elevation lotic waterways, whereas M. lucifugus, Lasiurus borealis, and Eptesicus fuscus were associated with high-elevation lentic waterways with sparse canopy cover. However, riparian conditions had weak relations with NMDS axes, possibly resulting in coincidental associations in some cases. Regression tree analysis indicated that higher bat species richness was associated with apparently uncommon small, high-elevation waterways with sparse canopy cover as well as larger streams and rivers that had wetlands adjacent to them. Including high-elevation waterways with existing management recommendations for endangered M. grisescens foraging areas (large, low-elevation streams and rivers) will be the most effective conservation strategy to benefit the most bat species in northwestern Georgia and probably elsewhere in the southern Appalachians.
I review the effects of habitat fragmentation on carabid beetles (Coleoptera, Carabidae) and examine whether the taxon could be used as an indicator of fragmentation. Related to this, I study the conservation needs of carabids. The reviewed studies showed that habitat fragmentation affects carabid assemblages. Many species that require habitat types found in interiors of fragments are threatened by fragmentation. On the other hand, the species composition of small fragments of habitat (up to a few hectares) is often altered by species invading from the surroundings. Recommendations for mitigating these adverse effects include maintenance of large habitat patches and connections between them. Furthermore, landscape homogenisation should be avoided by maintaining heterogeneity of habitat types. It appears that at least in the Northern Hemisphere there is enough data about carabids for them to be fruitfully used to signal changes in land use practices. Many carabid species have been classified as threatened. Maintenance of the red-listed carabids in the landscape requires species-specific or assemblage-specific measures.
Travinné ekosystémy jsou významnou součástí středoevropské krajiny. Polopřirozená travinná společenstva dnes tvoří v Evropě místa s vysokou biodiverzitou, jsou velmi náchylná k degradaci a k jejich efektivní ochraně je nutné znát vlivy různých typů managementu. Neodmyslitelnými obyvateli těchto ekosystémů jsou také zástupci rovnokřídlého hmyzu (Orthoptera), kteří zde hrají důležitou roli v potravní síti. Zároveň jsou vhodným indikátorem změn stanovištních podmínek, a to zejména struktury vegetace, čehož lze využít při zjišťování dopadů různých managementových opatření. Jedním z nejběžnějších a zároveň pro hmyz nejméně vhodných typů péče je dnes mechanizovaná seč. Nevhodná péče o travinné ekosystémy může ovlivňovat druhovou bohatost jak v měřítku lokálním tak i v měřítku krajiny. Snížení negativního dopadu seče ve prospěch biodiverzity lze docílit několika způsoby - např. zmírněnou intenzitou zásahu, a to posunutím nebo vynecháním první seče, nebo ponecháním neposečených ploch., Grasslands are an important part of the Central European landscape. Seminatural grasslands are considered to be biodiversity hotspots in Europe, with high conservation value. However, they are very unstable, and for their effective conservation it is necessary to know how different management systems affect the progression of the ecosystem. Orthopterans play an important role in the food web and they are also a good indicator of changes in habitat conditions, particularly in the vegetation structure, which can be used in determining the impact of different types of conservation management. Nowadays, one of the most common and least insect-friendly type of care is mechanized hay harvesting. Improper care can affect the species richness (both, on the local and landscape scale). The negative impact of mowing can be reduced in favour of biodiversity in several ways, as described (e.g., mitigating the intensity of the process by delaying or omitting the first mowing, or leaving uncut refuges)., and Oto Kaláb.
Meaningful ecological studies on insect communities require sampling protocols that take into consideration temporal fluctuations in abundance and species composition. Bees with their specific requirements for nutrition and nesting are good indicators of landscape structure and overall biodiversity, provided the ecological and seasonal patterns they show are taken into consideration. The present two year study traced the ecological and seasonal patterns on 2 km2 of a southern slope in the Swiss Alps, ranging from 1150 to 1550 m above sea level. The study area consisted mainly of grassland under different regimes, mostly hay meadows and pastures. By direct netting at five monthly intervals in each year a total of 247 bee species were recorded. This comprehensive sampling scheme identified one of the most diverse bee faunas in Central and Northern Europe, consisting of a statistically estimated 280 species. Most species were rare with 14.6% represented by a single individual. Ecological analysis of the bee community showed that the primitively eusocial species were over represented among the abundant species and the parasitic species among the rarest.
Both abundance and species richness were subject to marked seasonal variations. A substantial turnover in species composition as well as changes in ecological patterns were observed. More than 25% of all species were recorded in only one of the two years, in particular many of the parasitic species. Singletons accounted for a higher proportion when individual years rather than the pooled data were analysed. All these findings underline the importance of season-long sampling and sampling over more than one year if bees are to be used as indicators in ecological and studies on bee communities.
One way of reducing the rapid decline in biological diversity in agricultural landscapes is to establish wildflower areas. The species richness and abundance of heteropteran bugs in twenty 1- to 4-year-old wildflower areas and winter wheat fields were compared, and the effects of succession in the wildflower areas investigated. Vegetation and environmental parameters (plant species richness, vegetation structure, flower abundance, field size, surrounding landscape) and their effects on bug species were explored. Total species richness and abundance of bugs were significantly lower in wheat fields than in wildflower areas but did not differ in the wildflower areas of different ages. The numbers of zoophagous bugs in the wildflower areas were positively correlated with the age of the wildflower areas. Correspondence analysis showed that the bug species composition in the winter wheat fields was very similar but strongly separated from that in the wildflower areas. The species composition of bugs in the wildflower areas became increasingly dissimilar with advancing successional age. In a partial canonical correspondence analysis, the bug assemblage was significantly associated with the number of perennial plant species, the number of annual plant species and vegetation structure, which accounted for 13.4%, 12.6% and 7.2% of the variance, respectively. As wildflower areas clearly increased heteropteran diversity on arable land and bug species composition changed with increasing successional stage, the establishment of a mosaic of wildflower areas of different age is recommended as it enables the survival of heteropteran bugs with different life history traits.
Altogether 71 samples collected in 1968–2004 from the Rokytná and Loučka rivers were used to estimate proportional fish species richness from single-pass electro-fishing and probabilities of detection for individual fish species. Mean estimated species richness from single-pass sampling (p ́s1) was 95.4% and 96.2% of estimated total species richness for Rokytná and Loučka rivers, respectively. However, p ́s1 values for individual sites ranged from 71.4% to 100% of estimated total species richness. Additional species unique to the second pass were collected in 38% (Rokytná) and 22% (Loučka) of the samples. When assessing the fish assemblage structure by a multivariate technique (PCA), considerable inaccuracy between the single-pass and two-pass electro-fishing data was also observed. Decisions regarding standardized sampling effort and whether to conduct one or more electro-fishing passes must be based on study objectives. For more accurate evaluations of fish assemblage structure two-pass electro-fishing is recommended. Three-pass electro-fishing did not produce significant increase of species richness.