# Ten Years of Experience with Scientific TerraSAR-X Data Utilization
## 3 Results
### Proposal Analysis Overview
#### 3.1.2 Biosphere  
Geoscientific research in the biosphere domain is addressed by 15 percent of the proposals (see Figure 5), the majority of which is concerned with agricultural issues, specifically crop type mapping and monitoring. Most commonly, spatio-temporal backscatter variations are employed for crop type discrimination [57], crop production forecast [58], and mapping of phenological conditions [59]. In addition, surface characteristics like soil moisture [60] and their change due to tillage and harvesting activities are of interest [61]. Further studies map [62] and monitor rice growth [63; 64; 65].  
Mapping and monitoring of forests is another essential issue in biosphere-related applications. Here, high-resolution SAR data are used for the derivation of forest stand attributes, forest structure and biomass estimations. Generally, three basic sources of information from SAR data are utilized: Backscatter, coherence and phase-based approaches [66]. Besides, radargrame  
Figure 5: Thematic fields of biosphere-related TerraSAR-X proposals, sorted by frequency, specifically addressing agriculture, forest, wetland and grassland issues or, more generally, vegetation and land cover.  
estimation by determining tree heights through surface and terrain models [67; 68]. Also, changes of the forest cover over time are investigated, such as the impact of forest fires [69], degradation, deforestation and forest health [70].  
Several proposals target rather general issues of vegetation and land cover mapping such as the assessment of soil erosion processes [71], shrub growth monitoring [72], the detection and characterization of hedgerows [73], or biodiversity monitoring [73; 74].  
Wetlands are threatened by population growth, extension of agricultural land, and general human interventions in the water budget. Goals of the research community are, for example, to assess and better understand the wetland functions to improve land and water management [75]. Proposals and research with focus on need belts [76] and other wetland vegetation [77] belong to this group. Additionally, the possibility of applying differential interferometry for measuring water level and water level changes is investigated [78].  
A relatively small group of proposals addresses mapping and monitoring of grassland. The identification of grassland and especially its conversion into cropland is a relevant topic for studies on sustainable land use [79]. [PERSON] et al. [80] identify the economic use of grassland for hay production. SAR data are used for biomass estimation and monitoring of cutting activities [81].  
Most of the applications in the biosphere group use TerraSAR-X data for monitoring (65 percent of the proposals) and mapping purposes. Compared to 30 percent of the users requesting polarimetric data, SAR interferometry plays a minor role, but still 11 percent utilize InSAR products. Furthermore, change detection is addressed in 9 percent of the proposals. TerraSAR-X data are often synergistically used with other EO data in order to benefit from both the higher spatial resolution and higher frequency of the X-band in combination with other SAR and optical systems. This is evident through the 24 percent of the biosphere proposals describing multisensoral approaches.