Effects of grassland habitat loss on selection of nature’s contributions to people

Abstract

Nature's contributions to people (NCP) are nature's characteristics that are vital for human well-being. During recent years, the maintenance and safeguarding of these contributions has become the key issue in nature conservation. Variety of NCP are related to biodiversity of habitats. Biodiversity, in turn, is highly dependent on landscape composition and environmental conditions of habitats. Land use change, habitat degradation and destruction are the primary causes of biodiversity loss and also degradation of NCP's.

Our study was carried out on calcareous grasslands in Estonian islands Saaremaa, Hiiumaa, Muhu and on the mainland of Western Estonia. A total of 35 study sites were sampled. On each study site, we distinguished three successional stages (subsites): a) open alvar - good-quality alvar grasslands characterised by short herb layer and moderate (up to 30-40%) shrub cover (mostly Juniperus communis) reflecting historical state of alvars; b) shrubland - previously open alvar grasslands that have been overgrown with dense (<60% cover) juniper shrubs (J. communis); and c) afforested alvar - previously open alvar grasslands that have been afforested with Scots pine (Pinus sylvestris) in 1970-80s. We studied the effects of changing landscape structure and environmental conditions and compared the provisioning of pollination, pest regulation, climate regulation, soil quality and cultural benefits on every subsite. To assess the potential to provide pollination we used the abundance and species richness of butterflies and bumblebees as an indicator. Additionally, we observed the species richness and abundance of entomophilous plants to measure the potential to attract pollinators. Pest regulation was assessed using species richness and activity density of ground-dwelling spiders and predatory carabids. For climate regulation we used carbon stock and carbon sequestration potential. Soil fertility was assessed using abundance and richness of soil fauna, soil components (soil nutrients K, P, Mg and soil organic matter) and soil depth. To find out the potential to provide cultural benefits we carried through a survey where respondents were expected to value photos of alvar grasslands with different shrub cover and in different successional stages to determine what kind of landscape people would prefer to visit and what do they value about these sceneries. We also asked how much they would be willing to pay to preserve such habitats.

We documented vast changes in landscape structure and in environmental conditions of grassland habitats as a result of overgrowing or afforestation. These changes had also negative impacts on the sustainable supply of observed NCP's. Ecosystem restoration efforts like LIFE+ program project "LIFE to Alvars" could potentially help to decrease the degradation of alvar grasslands and help to maintain vital ecosystem benefits these semi-natural grassland communities provide.