Conservation management is expected to increase local biodiversity, but uniform management may lead to biotic homogenization and diversity losses at the regional scale. We evaluated the effects of ...renewed grazing and cutting management carried out across a whole region, on the diversity of plants and seven arthropod groups. Changes in occurrence over 17 years of intensive calcareous grassland management were analysed at the species level, which gave insight into the exact species contributing to regional homogenization or differentiation. Reponses were compared between species differing in habitat affinity, dispersal ability, food specialisation and trophic level. Local species richness increased over the sampling period for true bugs and millipedes, while carabid beetles and weevils declined in local species richness. Species richness remained unchanged for plants, woodlice, ants and spiders. Regional diversity and compositional variation generally followed local patterns. Diversity shifts were only to a limited extent explained by species’ habitat affinity, dispersal ability, trophic level and food specialisation. We conclude that implementation of relatively uniform conservation management across a region did not lead to uniform changes in local species composition. This is an encouraging result for conservation managers, as it shows that there is not necessarily a conflict of interest between local and regional conservation goals. Our study also demonstrates that shifts in diversity patterns differ markedly between taxonomic groups. Single traits provide only limited understanding of these differences. This highlights the need for a wide taxonomic scope when evaluating conservation management and demonstrates the need to understand the mechanisms underlying occurrence shifts.
► We grouped species into strategies based on life-history trait combinations. ► Differences in occurrence of strategies in the field revealed two main bottlenecks. ► Current habitat isolation ...strongly limits the distribution of poor dispersers. ► Current autumn management causes too cold conditions during nest founding. ► Life-history strategies are a valuable tool providing mechanistic understanding.
Species’ life-history traits underlie species–environment relationships. Therefore, analysis of species traits, combined into life-history strategies, can be used to identify key factors shaping the local species composition. This is demonstrated in a case-study on ants in chalk grasslands. We developed four life-history strategies based on traits related to reproduction, development, dispersal and synchronization that are documented in the literature. These theoretical strategies reflect different responses to certain environmental conditions. They can be characterized as generalists (G), poor dispersers (D), species whose distribution is limited to sites with high food availability (F) and species that are restricted to sites with high soil temperatures during nest founding (T). Next, we tested whether the occurrence of these strategies differed between six Dutch chalk grasslands and four reference sites situated in Germany and Belgium. We found significant differences in species numbers between sites for strategies D and T but not for strategies F and G. The differences could be explained by differences in connectivity and microhabitat conditions; species richness of strategy D decreased exponentially with increasing distance to the next nearest chalk grassland, while summer soil temperature strongly affected species richness of strategy T. From these relationships we could successfully identify the most relevant bottlenecks for the occurrence of both of these strategies in Dutch chalk grasslands. Management recommendations resulting from this analysis include adapting the management timing in Dutch chalk grasslands and focussing on counteracting habitat isolation. With this case-study we demonstrate that the life-history strategy approach is a valuable alternative to approaches that try to identify key factors by analysing the variation in environmental parameters. The main advantage of the presented alternative is the focus on mechanistically understanding species responses, allowing a comparison of processes rather than occurrences of single species.
The impact of agriculture on wood ants of the
Formica rufa
group was investigated in a small-scale agricultural landscape with many woodland fragments in the east of the Netherlands. An inventory of ...nests was carried out in 1986, and repeated in 2014. The number of nests of
F. rufa
and
F. polyctena
had drastically decreased during the intervening 28 years, especially in small patches of woodland bordering a maize field. The species
F. rufa
, which mainly disperses by flight of the queen, seems to be better adapted to habitat fragmentation than
F. polyctena
, where dispersal is mainly by colony splitting. However, the flying strategy can only be successful in a landscape where most woodland fragments have a good quality habitat; in the study area, the habitat quality had deteriorated. This is ascribed to the development of a tall, nitrophilous vegetation, a result of considerable nitrogen deposition from the atmosphere and the spraying of manure. The regional survival of wood ants in the east of the Netherlands is at risk in the agricultural landscapes we studied. This is due to the increasing probability of colonies becoming extinct and the decreased probability of a queen colonizing habitat patches. However, the negative influence of agriculture on the edge vegetation of patches of woodland can be decreased by leaving a wide strip between the arable land and the woodland that receives no manure.
Lasius brunneus can often be found in deciduous forests, where it nests in old trees. However, the species seems to be rather opportunistic in its choice of a nesting place. Nests can also be found ...in isolated trees, wooden beams (or other wooden pieces) in homes and even in the ground under stones. In this article, I describe the observation of workers, males and females of this ant on the surface of a wood ant nest (of Formica rufa) in late October. The wood ants did not pay attention to the intruders. Possibly, the L. brunneus ants found food inside the wood ant nest, because there was no tree or bush in the neighbourhood where the ants could milk aphids. Generally this species has its wedding flight within the period May-July. It is unusual for sexuals of this species to be active so late in the year.Original Abstract: De boommier, Lasius brunneus Latreille, nestelt doorgaans in oude bomen (fi-guur 1). Het betreft meestal eik (Quercus), maar soms ook een beuk (Fagus), berk (Betula), linde (Tilia), kastanje (Castanea) of es (Fraxinus). De soort komt vooral in loof-bossen voor, al bouwt hij z'n nest ook wel eens in een geisoleerde boom. In huizen wordt hij soms aangetroffen in een oude balk. Meestal betreft het hout met een hoog vochtgehalte dat door een schimmel is aangetast (Brink 2011). In Amerongen (Ut) zat ooit een nest in een balk van een boerderij. Tijdens de bruidsvlucht liepen zo veel gevleugelde mieren tegen de ramen dat ze de kamer verduisterden. De bewoner vroeg me hoe hij van die gevleugelde insecten verlost kon worden. Het advies was eenvoudig: 'zet de ramen maar open'.
The Besthmenerberg is a small sandy hill (maximum altitude 32 m), which was formed by glaciers during the penultimate ice age. The hill is mainly covered with forest and also with low heath ...vegetation. The nests of all Formica species occurring in the area have decreased over a period of 20 years. Of the encountered species, Formica truncorum, a boreo-alpine species, is very rare in The Netherlands. Its existence is threatened: the number of nests on the Besthmenerberg is decreasing. The number of nests of two other boreo-alpirie species has decreased as well, i.e. F. exsecta and F. pressilabris. This is due to local extinctions and partly to the fusion of nest populations, which belong to a polydomous colony. Fusion and extinction of nest populations are mainly driven by the closing of the canopy as trees and bushes become older. In 2009 the Forestry Service tried to enlarge the habitat of F. truricorum by cutting some trees and bushes. However, this did not improve the situation very much. The habitat of Formica species could be enlarged much more by cutting exotic trees and bushes, like Prunus serotina, Quercus rubra, Amelanchier lamarckii and Pseudotsuga menziesii. They give much shade and do not harbour aphids, which provide essential ant food in the form of honeydew. The cut logs should be removed from the area. However, the help of volunteers will be crucial since the government is decreasing the budget of the State Forestry drastically.Original Abstract: In de omgeving van Ommen komen zeldzame en kwetsbare mieren-soorten voor van het geslacht Formica. Enkele soorten zijn wettelijk beschermd, onder andere de stronkmier. Deze komt in ons land vrijwel uitsluitend in deze regio voor. Op grond van de verspreidings-gegevens van de stronkmier van 1995 is de Besthmenerberg bij Ommen beschouwd als het kerngebied van de regionale metapopulatie. Het aantal nesten is echter gedurende de afgelopen 20 jaar aanzienlijk afgenomen. Dit geldt ook voor de overige Formica-soorten die in dit gebied voorkomen. De afname is te verklaren door de afname van het leefgebied doordat sommige open plekken dichtgroeien met struiken. Bovendien zijn de bomen gegroeid waardoor ze meer schaduw op open terrein werpen. Verder heeft de aanplant van dennen in delen van het terrein bijgedragen aan het uitsterven van mierenvolken. Om de kans op het lokaal voortbestaan van warmteminnende soorten te vergroten is het gewenst dat uitheemse soorten bomen en struiken worden verwijderd en het dichtgroeien van open vegetatie wordt voorkomen.
In the peat bogs of the Bieszczady National Park an inventory of the Black bog ant (Formica picea Nyl.) was made in order to get an impression of the probability of its survival in SE Poland. Three ...habitat networks are distinguished, which are situated too far from each other for (re)colonization by means of flying queens. The largest network includes five peat bogs. In two of them F. picea was found. The species was not found in peat bogs which belong to the other habitat networks. The quality of the peat bogs depends on management strategies, currently challenged by two main threats: desiccation and the influx of nutrients. This process will speed up the succession of the vegetation. As a result dwarf shrubs are encroaching on habitat areas of F. picea, where Sphagnum species are still dominating in the moss layer
In the past, extensive areas in Drenthe (The Netherlands) were covered by peat bogs and wet heath lands, but nowadays only relatively small fragments are left. During the second half of the 20th ...century the quality of these fragments decreased, due to lowering of the water table and the input of nutrients. These factors will have a negative effect on the survival of species which are adapted to these stable type of biotopes, like the Black bog ant. The distribution pattern was analysed within a study area of 750 km^sup 2^, in order to find out if this species will survive in a landscape where its habitat is severely fragmented. Using multiple logistic regression analysis it appears that size and quality of the habitat patches, as well as openness of the environment, contribute significantly to patch-occupancy. No correlation was found between the probability of a patch being occupied and its distance to the nearest occupied patch. It appears that the spatial cohesion of local populations by means of flying queens is weak or absent on the scale of the study area. Only in parts of the area, where the distance between habitat patches is less than 3 km in open field, a habitat network may still exist. However, with ongoing habitat loss a threshold will be passed and the species will ultimately become extinct.PUBLICATION ABSTRACT
Do ants need protecting? Mabelis, A A
Entomofauna,
11/2007, Letnik:
28, Številka:
31
Journal Article
Generally, species can be protected by the conservation and sustainable management of the ecosystems in which they occur. However, some vulnerable and threatened species need special attention. In ...order to protect these species effectively, data should be available on their conservation status, their decline and the threats that are operating. Such data are lacking in the recent Red List of the IUCN. Most ant species mentioned in this list are social parasites. The question arises whether these species can be protected more effectively by protecting and managing the biotope of their more easily found host species. Presently, it is not clear who will collect and interpret the data for making a selection of Red List species. Attention should also be paid to umbrella species, which are important for the survival of other species, and keystone species, which play an important role in an ecosystem.
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