TY  - JOUR
A1  - Reinermann, Sophie
A1  - Gessner, Ursula
A1  - Asam, Sarah
A1  - Kuenzer, Claudia
A1  - Dech, Stefan
T1  - The Effect of Droughts on Vegetation Condition in Germany: An Analysis Based on Two Decades of Satellite Earth Observation Time Series and Crop Yield Statistics
JF  - Remote Sensing
N2  - Central Europe experienced several droughts in the recent past, such as in the year 2018, which was characterized by extremely low rainfall rates and high temperatures, resulting in substantial agricultural yield losses. Time series of satellite earth observation data enable the characterization of past drought events over large temporal and spatial scales. Within this study, Moderate Resolution Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) (MOD13Q1) 250 m time series were investigated for the vegetation periods of 2000 to 2018. The spatial and temporal development of vegetation in 2018 was compared to other dry and hot years in Europe, like the drought year 2003. Temporal and spatial inter- and intra-annual patterns of EVI anomalies were analyzed for all of Germany and for its cropland, forest, and grassland areas individually. While vegetation development in spring 2018 was above average, the summer months of 2018 showed negative anomalies in a similar magnitude as in 2003, which was particularly apparent within grassland and cropland areas in Germany. In contrast, the year 2003 showed negative anomalies during the entire growing season. The spatial pattern of vegetation status in 2018 showed high regional variation, with north-eastern Germany mainly affected in June, north-western parts in July, and western Germany in August. The temporal pattern of satellite-derived EVI deviances within the study period 2000-2018 were in good agreement with crop yield statistics for Germany. The study shows that the EVI deviation of the summer months of 2018 were among the most extreme in the study period compared to other years. The spatial pattern and temporal development of vegetation condition between the drought years differ.
KW  - drought
KW  - time series
KW  - heat wave
KW  - agriculture
KW  - climate extremes
KW  - climate change
KW  - crop statistics
KW  - MODIS
KW  - Germany
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225165
VL  - 11
IS  - 15
ER  - 
TY  - JOUR
A1  - Thonfeld, Frank
A1  - Gessner, Ursula
A1  - Holzwarth, Stefanie
A1  - Kriese, Jennifer
A1  - da Ponte, Emmanuel
A1  - Huth, Juliane
A1  - Kuenzer, Claudia
T1  - A first assessment of canopy cover loss in Germany's forests after the 2018–2020 drought years
JF  - Remote Sensing
N2  - Central Europe was hit by several unusually strong periods of drought and heat between 2018 and 2020. These droughts affected forest ecosystems. Cascading effects with bark beetle infestations in spruce stands were fatal to vast forest areas in Germany. We present the first assessment of canopy cover loss in Germany for the period of January 2018–April 2021. Our approach makes use of dense Sentinel-2 and Landsat-8 time-series data. We computed the disturbance index (DI) from the tasseled cap components brightness, greenness, and wetness. Using quantiles, we generated monthly DI composites and calculated anomalies in a reference period (2017). From the resulting map, we calculated the canopy cover loss statistics for administrative entities. Our results show a canopy cover loss of 501,000 ha for Germany, with large regional differences. The losses were largest in central Germany and reached up to two-thirds of coniferous forest loss in some districts. Our map has high spatial (10 m) and temporal (monthly) resolution and can be updated at any time.
KW  - forest
KW  - canopy cover loss
KW  - drought
KW  - Sentinel-2
KW  - Landsat-8
KW  - disturbance index
KW  - time series
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-255306
SN  - 2072-4292
VL  - 14
IS  - 3
ER  -