Abstract
Abstract. The identification and surveillance of agricultural management and the measurement of biophysical canopy parameters in grasslands is relevant for environmental protection as well as for political and economic reasons, as proper grassland management is partly subsidized. An ideal monitoring tool is remote sensing due to its area wide continuous observations. However, due to small-scaled land use patterns in many parts of central Europe, a high spatial resolution is needed. In this study, the feasibility of RapidEye data to derive leaf area index (LAI) time series and to relate them to grassland management practices is assessed. The study area is the catchment of river Ammer in southern Bavaria, where agricultural areas are mainly grasslands. While extensively managed grasslands are maintained with one to two harvests per year and no or little fertilization, intensive cultivation practices compass three to five harvests per year and turnover pasturing. Based on a RapidEye time series from 2011 with spatial resolution of 6.5 meters, LAI is derived using the inverted radiation transfer model PROSAIL. The LAI in this area ranges from 1.5 to 7.5 over the vegetation period and is estimated with an RMSE between 0.7 and 1.1. The derived LAI maps cover 85 % of the study area’s grasslands at least seven times. Using statistical metrics of the LAI time series, different grassland management types can be identified: very intensively managed meadows, intensively managed meadows, intensively managed pastures, and extensively managed meadows and moor. However, a precise identification of the mowing dates highly depends on the coincidence with satellite data acquisitions. Further analysis should focus therefor on the selection of the temporal resolution of the time series as well as on the performance of further vegetation parameters and indices compared to LAI.
Highlights
The identification and surveillance of agricultural practices, especially of management intensities, is relevant for a range of ecological, conservation, and political issues
Due to the small-scaled land use patterns in the alpine areas of central Europe, the used remote sensing images need a high spatial resolution, which becomes increasingly feasible with relatively new sensors such as RapidEye, Landsat 8, and, soon, Sentinel-2
The preprocessing of the level 1B data consisted of a transformation into UTM (WGS 84 datum) projection by using a nearest neighbor algorithm; orthorectification using RPCs associated with the RapidEye data and a 30 m Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM); precise georeferencing using ground control points; and a topographic and atmospheric correction using ATCOR (Richter and Schläpfer 2012)
Summary
The identification and surveillance of agricultural practices, especially of management intensities, is relevant for a range of ecological, conservation, and political issues. Mostly large-scale biomes such as semi-arid or subtropical grasslands have been assessed (Numata et al 2007, Kurtz et al 2010) Another issue is the temporal resolution of grassland observations, since with high spatial resolution data the coverage of a certain study area at regular intervals is often impeded, especially in areas prone to frequent cloud cover such as the Alpine area. While the canopy light absorption, which is the process influencing VI levels, can be diminished e.g. by droughts or senescence, the actual biomass status can be better represented by LAI Descriptive statistics such as the range or the accumulated LAI are directly comparable between sites as the resulting numbers are absolute values.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
