Sensor Needs for Effective Measurement of Non-Photosynthetic Vegetation
Abstract
Non-photosynthetic vegetation (NPV) is an important carbon pool in agricultural and non-agricultural environments. In cultivated agricultural environments, NPV manifests itself in the form of crop residues, or the stems, cobs, leaves and other plant parts left in the field after harvest. Modern conservation tillage systems leave substantial quantities of crop residues on the soil surface in comparison with conventional intensive tillage systems, which plow residues under the soil surface. Crop residue cover is an important parameter in agricultural carbon cycle and water quality models. These crop residues, when left intact on the surface, protect the soil from wind and water erosion, reduce evaporation, recycle nutrients, and add organic carbon to the soil surface when they decompose. However, crop residues can be harvested for biofuel feedstock or animal feed and fodder, even in tillage systems which minimally disturb the underlying soil. In rangelands, non-photosynthetic vegetation is an important indicator of rangeland health and soil quality. In non-agricultural settings, NPV can serve as fuel for brush files. As such, the removal of NPV can result in the erosion and transport of soils, and thus, SOC. Current ground-based methods of NPV estimation are tedious and not well-suited for estimating over large areas. Current multispectral spaceborne platforms are not well-suited for estimation of NPV as they lack the appropriate spectral bands in the shortwave infrared (SWIR) portion of the electromagnetic spectrum. The ideal system for measurement of NPV utilizes the Cellulose Absorption Index (CAI), requiring three SWIR bands. Alternatively, estimation of NPV is possible with the Shortwave Infrared Normalized Difference Residue Index (SINDRI) utilizing ASTER bands 6 and 7. While SINDRI is not as effective as CAI, it outperforms the remaining NPV indices and is not as expensive to implement as CAI. SINDRI can also be applied to existing ASTER imagery acquired prior to the SWIR detector failure in April 2008. Future systems incorporating NPV detection bands should have 12-bit or better quantization, a signal-to-noise ratio of > 250, temporal resolutions of < 7 days to ensure cloud-free scenes, and pixel sizes < 60 m.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.B51C0321S
- Keywords:
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- 0402 BIOGEOSCIENCES / Agricultural systems;
- 0428 BIOGEOSCIENCES / Carbon cycling;
- 0480 BIOGEOSCIENCES / Remote sensing;
- 0486 BIOGEOSCIENCES / Soils/pedology