## 4 Discussion  
We identified four distinct clusters of grassland parcels with biomass trends over 25 years for the Orbroich site. While two clusters remained relatively constant at high NDVI levels, the other two clusters showed marked increases in annual vegetation biomass over time, reaching or nearing the \"constant\" clusters by 2013. For the two increasing biomass clusters, the starting year of increase occurred at different times. By 2013, grassland conditions were less diverse compared to 1989. Several anthropogenic factors may be related to these increases. There has been a decrease in dairy farming in the area coupled with an increase in silage production [28]. This shift from extensively managed grassland (i.e., dairy pasture) to intensive silage grassland may in part explain the trends identified. Additionally, the number of biogas generation plants increased significantly between 2000 and 2017 with the Renewable Energy Sources Act [28]. Across Germany, the area of silage maize for biogas increased by approximately 700,000 ha between 2007 and 2018 [28; 29], which overlaps the timeframe of the increasing NDVI of Cluster 1 for both Orbroich and Wahnbachtal. Grasses and other silage crops are more intensively managed to generate additional biomass for conversion to biogas. In Wahnbachtal, five clusters were identified with two clusters having a relatively constant annual average biomass, two clusters with an increasing biomass, and one cluster with a decreasing trend (Figure 5). A preliminary evaluation examined generalized changes in grassland parcels over time using Google Earth time series imagery. This evaluation indicated that Clusters 1 and 3 were a temporal mixture of grassland and arable uses over the time period. Cluster 1 primarily had early changes from arable to intense grassland uses and Cluster 3 parcels changed from early grassland use to mixed use (e.g., silage, arable, grassland combinations). The parcels in the two temporally constant clusters (4 and 5) have likely been continual pasture and/or meadow (hay) uses over the time period with no mix of arable crops during those years. Parcels examined in Cluster 2 (which had a large increase in biomass over time) also had little or no mixing with arable uses; however, the intensity of grassland use increased over time (e.g., change from pasture to intense meadow (hay) or silage production). This cluster also included some parcels permanently changed from arable to grassland within the 25-year window (but not fluctuating back and forth). Cultural changes in this area from 1989 to 2015 include the addition of nearby biogas plants and an increase in recreational horse riding and farming. These factors may affect grassland management practices to intensify biomass production for biogas or silage. Although distinct clusters of grassland parcels with clear trends over time were observed, there were additional factors influencing the results that should be considered. These factors are listed below and discussed in Supplementary Materials:  
* Designation/definition of grassland polygons;
* Satellite image selection and pre-processing;
* Satellite image normalization;
* Use of NDVI as a proxy for biomass;
* Temporal aspects of metrics for grassland parcel characterization;
* Within-cluster similarity. The integration of more than one hundred satellite images spanning several decades into a single spectrally normalized time series and the subsequent analysis method used are not limited to the specific locations presented here. This investigation on grassland change and local insect abundance is transferable and can be applied to other geographic regions. This could include other locations observed in the insect study of [3; 4; 5], and other studies [30]. However, the interpretation of the temporal trends and their correlation to environmental changes in the landscape will differ depending on the area being studied.