Browsing by Subject "Skylark"

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Fernerkundungsgestützte Analyse und Bewertung ökologischer Auswirkungen des Anbaus von Bioenergiepflanzen auf die Agro-Biodiversität anhand der Modellierung der Habitatansprüche der Feldlerche (Alauda arvensis)
(2017) Schlager, Patric; Schmieder, Klaus
For the first time in 2002, the transformation of the conventional energy system into a system based on renewable energies was politically and legally decided in Germany. On the regional level numerous communities and municipalities followed this decision by voicing their own political resolutions, addressing the coverage of energy consumption with renewable energies. Their implementation is accompanied by a spatial expansion of bioenergy crops which lead to a controversial discussion about food safety, biodiversity and landscape change. Framed by the above mentioned discussion, this study assesses potential changes of skylark (Alauda arvensis) occurrence caused by a spatial expansion of bioenergy crops in the municipality of Schwäbisch Hall, Germany. The skylark was selected due to the comprehensive state of research about skylarks, their endangerment (“Red list of German breeding birds”), and the status as umbrella species for open agricultural landscapes (skylarks typically avoid vertical structures like hedges or edges of forests). The latter emphasizes their role as representatives for other species which are potentially affected by an expansion of bioenergy crops. This study is based on a stratified bird monitoring scheme of Baden-Württemberg, which was developed during a project that aimed to set up an indicator for species richness and was financed by the Bundesministerium für Ernährung, Landwirtschaft und Verbraucherschutz (BMELV). From the bird monitoring scheme, the stratum, which covers the municipality of Schwäbisch Hall, was extracted and served as a base for the development of a Generalized Linear Habitat Model of the skylark. In order to assess potential habitat changes caused by an expansion of bioenergy crops, Schwäbisch Hall was mapped with an airborne remote sensing technology in 2011. The resulting aerial images were transformed into orthophotos and later classified (focusing on agricultural areas) with an object oriented image analysis approach. Based on the outcomes of the habitat association model and the land use classification, skylark territories were predicted for 1 km² plots covering Schwäbisch Hall. For an in-depth understanding of ecological impacts from expanded bioenergy cropping, a bioenergy scenario was developed considering § 17 BBodSchG (national soil protection act) and regional food security. Based on the scenario, skylark territories were predicted for 1 km² plots covering Schwäbisch Hall. The most reasonable habitat association model resulted in a negative binomial Generalized Linear Model with the predictors winter sown crops and mean patch size per plot. Model performance was assessed by Wald z-statistics with p-values, ANOVA, explained variance, theta, residuals, AIC, and independent field data. Field data was only available for one plot. Therefore, the field data only indicate model performance. The comparison of the model predictions with the field data resulted in an accuracy of 92.21%. The land use classification resulted in the following five classes: 1. winter sown crops (33985.78 ha), 2. maize (9621.36 ha), rapeseed (2952.36 ha), unidentified crops (7244.18 ha), and grassland (30720.88 ha). Grasslands were not mapped by remote sensing techniques, but taken from a digital landscape model. Accuracy assessment showed an overall accuracy of 89.16 % and 0.78 kappa statistics. Prediction of skylark territories based on the land use classification of 2011 resulted in 46269 territories, or a mean density of 8.4 territories per 10 ha on agricultural areas and 5.4 territories per 10 ha on agricultural and grassland combined areas. The scenario assumed a three partite crop rotation (maize, rapeseed, winter sown crops) and a mean value of 0.17 ha per inhabitant for food security. Areas for fodder production were considered in course of the calculation of food security because Schwäbisch Hall is characterized by many livestock farms, which made it necessary to avoid conflicts between potential bioenergy sites and areas for fodder production. Considering the above mentioned assumptions, Schwäbisch Hall has a bioenergy potential of 5955 ha for maize and 15033 ha for rapeseed cropping. The results of the bioenergy scenario were randomly distributed to the land use polygons which resulted from the remote sensing analysis. With that, prediction of skylark territories based on the bioenergy scenario was feasible. Skylark territories for the bioenergy scenario resulted in 36472 territories, or a mean value of 6.8 territories per 10 ha on agricultural areas and 4.3 territories per 10 ha on agricultural and grassland combined areas. Considering both land use options, skylark territories declined by 8797 in total numbers or by 19.43 % in relative numbers. In addition to the land use options described above, landscape structure and territory distribution were analyzed based on six landscape units (Naturräumliche Haupteinheiten) covering the municipality of Schwäbisch Hall. The analysis revealed an agriculturally dominated northwestern part, with high numbers and mean values of skylark territories, and a grassland/forest dominated southeastern part, with lower numbers and mean values of skylark territories. The relative decline of these territories between the two land use options within the landscape units resulted approximately in 22 % in the northwestern and approximately 11-15 % in the southeastern part. The results indicate that an expansion of bioenergy crops will have negative effects on breeding birds in open agricultural landscapes which already suffer from degraded habitat conditions. Based on the assumptions of this study, skylark territories will decline by approximately 20 % in comparison to 2011. Yet, considering the results of the indicator report of the German National Strategy on Biodiversity (BMU 2010) and the European Bird Census Council the baseline of 2011 already represents a degraded situation in terms of habitat quality for agricultural breeding birds.