The importance current and historical landscape structure and biodiversity on the provision of ecosystem services in cultural landscapes with high conservation values

Abstract

Calcareous semi-natural alvar grasslands in Estonia have lost up to 80% of their area since the 1930s due to changes in human activities and land use. Recently, under the European Union LIFE+ Nature project "Life to alvars", this situation has improved as 1500ha of these semi-natural grasslands have been recovered. These changes over time in landscape structure have strong effects on biodiversity and ecosystem processes, resulting also on profound impacts on the provision of ecosystem services (ES) and human well-being. However, for many ecosystem characteristics, changes in the landscape do not have immediate effects but are manifested after a considerable time-lag. Not considering this differences in the ES responses to changes over time can cause an over or underestimation of the ES supply. We investigated the effects of changing landscape structure on the supply of ES in cultural landscapes with high conservation values. We propose that the presence of time-lags for the supply of ES depends on its link to biodiversity due to intrinsic ecological dynamics.

We studied 41 calcareous grasslands in west Estonia which are part of the "life to alvars" project but have not been yet restored. For each grassland, we calculated the landscape structure (area and connectivity) using historical (1930) and current (2010) land use and vegetation maps. We also assessed three ES with different links to biodiversity. The link to biodiversity was given by the different combination of indicators used to calculate the service. Pollination, with a strong link to biodiversity, was calculated as the average of abundance and richness of wild pollinators (butterflies and bumble bees) previously standardized. Carbon sequestration, with a weak link to biodiversity, was calculated as the standardized amount of soil organic carbon. Soil fertility was assessed using the average of two standardized sets of indicators. One set with a strong link to biodiversity (abundance and richness of soil biodiversity) and another set with a weak link to biodiversity (soil depth, P, K, and soil organic matter content). First, we analysed if the landscape structure had significantly changed over time using generalized linear models. Then, we analysed using boosted tree regressions the relative importance of the historical and the current landscape in the provision of ecosystem services.

Our results show that the landscape has suffered a significant area and connectivity loss since 1930. Regarding the importance of historical and present landscape on the provision of ES, the results show that ES with a weak link to biodiversity could show time-lagged responses as the historical landscape was more important than the current landscape, contrary to what happened to those strongly linked to biodiversity ES. Hence, incorporating the ES link to biodiversity and historical and present landscape when assessing ES provision could prevent potential misestimations of ES.