Abstract: Land use change has altered the productivity and water use of plants and soils across diverse ecosystems, but long term and consistently collected datasets documenting these changes are few and far between. He we show 33 years of remotely sensed plant productivity and water use at the W.K. Kellogg Biological Station Long Term Ecological Research site in southwest Michigan, USA. This study site includes 11 different replicated land use treatments ranging from old-growth temperate deciduous forest to intensive row crop agriculture. Utilizing images from 7 Landsat and Sentinel satellites we produced daily estimates of gross primary production and evapotranspiration by applying recently refined light use efficiency and surface energy balance models. Furthermore, we validated these models by comparing our estimates to nearby eddy covariance towers, hand-sampled biomass inventories and catchment scale water budgets from stream gauge data. We found that gross primary production ranged from over 2000 g C m-2 y-1 in the old-growth temperate deciduous forest to less than 1000 g C m-2 y-1 in years when a new rotation of poplar trees was planted. Different agricultural practices impacted productivity timing, especially weed and winter plant cover management strategies. Unmanaged abandoned agricultural fields increased their productivity over the 33-year study period as trees established. For evapotranspiration, we found similar trends with over 800 mm y-1 in the old-growth temperate deciduous forest and less than 500 mm y-1 in years when a new rotation of poplar trees was planted. Differences in evapotranspiration among agricultural management strategies were more muted than the differences in gross primary production. However, the establishment of trees in the abandoned agricultural fields significantly increased evapotranspiration rates over the 33-year study period. Overall, we found that combining remotely sensed images with empirically validated models of plant productivity and water use yielded novel insights into the long-term effects of land use change at this site. Our results shed light on the impacts land use change is having on ecosystem functioning across the Upper Midwest, USA.
