Rhinanthus: a tool for restoring diverse grassland?

The restoration of species-rich grasslands is often hindered by high residual soil fertility as a result of, e.g., intensive farming. The establishment of a diverse range of target species on such sites requires the reduction of soil fertility or of the vigour of competitive plants. Current methods to achieve these aims are often unsuccessful or complicated and expensive. It has been suggested thatRhinanthus species could be used to decrease the growth of competitive plants and enhance species diversity. We review evidence for this potential and suggest five key attributes that makeRhinanthus species a practical restoration tool.Rhinanthus species are natural components of species-rich grasslands (attribute 1), and seed of some species is relatively low cost and easily obtainable (2). Recent work has shown that certainRhinanthus species reduce the vigour of competitive species, especially agricultural grasses, and allow establishment and persistence of target species (3). We analyze demographic data and show that certainRhinanthus species have the ability for rapid population growth and spread, even in fertile grasslands (4). We also show that it is relatively easy for land managers to limit the population size ofRhinanthus species and prevent damage (e.g. excessive loss in production or invasion by weeds) to grasslands by excessive densities (5). We give suggestions for further research, including: the range of species-poor grasslands into whichRhinanthus can be introduced successfully and whichRhinanthus species should be used; the mechanisms by whichRhinanthus enhances diversity in restored grasslands; whether the ecotype or subspecies ofRhinanthus used affects restoration success; how management methods affect population growth and spread ofRhinanthus; and whether other parasitic plants could be used in habitat restoration.     

Knowledge-based models for predicting species occurrence in arable conditions

This paper explores the potential of rule-based habitat models to predict the occurrence of some common species in arable conditions. Models were developed for 10 arable plant species, 7 Hemiptera species, 8 carabid species and for 5 bird species whose ecology was sufficiently known. Rule sets linking species occurrence to environmental variables were produced using available literature and expert knowledge about ecological requirements of the selected species. Environmental variables described the nature and condition of habitats at various scales, ranging from vegetation quadrat to the landscape in a 1 km radius of species sampling sites. The performance of the 34 models developed was assessed in two areas of England. Results show the rule-based habitat models developed for arable plants and birds were not very successful with Cohen's k values often <0.4 for plants and very close to 0 for all bird species. Conversely, rule-based models performed surprisingly well for carabids and Hemiptera with k values on average >0.4. This suggests that ecological knowledge on these invertebrate species is more complete than we expected. The effect of species prevalence on model performance and the potential application of knowledge-based habitat models in the context of biodiversity assessment are discussed.