EVALUATION OF SPATIAL TRENDS IN BIOMASS AND LAI IN HETEROGENEOUS TREE-SHRUB ECOTONES

SEMI-ARID ECOSYSTEMS WHICH DOMINATE MUCH OF THE WESTERN US ARE HIGHLY VULNERABLE TO DISTURBANCE. DROUGHTS FIRE INVASIVE SPECIES AND LAND USE CAN SIGNIFICANTLY ALTER THE FUNCTIONAL PHYSIOLOGICAL STRUCTURAL AND DEMOGRAPHIC PROPERTIES OF SEMI-ARID ECOSYSTEMS. THESE DISTURBANCES HAVE ALSO RESULTED IN REGIONAL CHANGES IN THE DISTRIBUTION OF WATER IN THE HYDROLOGIC CYCLE (E.G. PRECIPITATION SOIL MOISTURE SNOW WATER STORAGE AND RUNOFF). MANY MUNICIPALITIES AND AGRICULTURE ARE RELIANT UPON WATER RESOURCES (TYPICALLY SNOWMELT FROM MOUNTAIN DRAINAGES) FROM WESTERN US SEMI-ARID WATERSHEDS. HOWEVER THERE STILL REMAINS A GAP IN UNDERSTANDING THE RELATIONSHIP BETWEEN VEGETATION DISTRIBUTION SNOW DEPTH AND SNOW WATER EQUIVALENT ACROSS SPACE AND TIME. BIOMASS AND LAI (LEAF AREA INDEX) ARE TWO STRUCTURAL TRAITS THAT ARE LINKED TO THE FUNCTIONAL AND PHYSIOLOGICAL STATUS OF PLANTS AND CAN BE USED TO MONITOR DISTURBANCE AS WELL AS FOR SNOW STUDIES TO CONSTRAIN UNCERTAINTIES IN SNOW DEPTH SNOW ALBEDO SWE AND HENCE SNOW MELT TIMING AND RUNOFF ESTIMATES. STRUCTURAL TRAITS ESTIMATION IN LOW STATURE AND SPARSE VEGETATION COMMUNITIES IS CHALLENGING WITH REMOTE SENSING INCLUDING POINT CLOUD BASED LIDAR AND OPTICAL RESPONSES. EMERGING DATA AVAILABILITY OF FULL-WAVEFORM LIDAR PROVIDES ADDITIONAL DATA MATRICES TO CAPTURE VEGETATION BIOPHYSICAL CHARACTERISTICS IN DETAIL. IN THIS STUDY I WILL UTILIZE PREVIOUSLY-COLLECTED AIRBORNE SNOW OBSERVATORY (ASO) FULL-WAVEFORM DATASETS AND SIMULATED LARGE FOOTPRINT GEDI LIDAR TO QUANTIFY UNCERTAINTIES IN LAI AND BIOMASS ESTIMATES IN REYNOLD S CREEK EXPERIMENTAL WATERSHED (RCEW) ID AND IN GRAND MESA (SNOWEX CAMPAIGN) CO. THIS RESEARCH WILL DEVELOP METHODS AND ALGORITHMS TO REDUCE THE UNCERTAINTY IN QUANTIFYING THESE PARAMETERS FOR WESTERN WATERSHEDS AND WILL ALSO BE APPLICABLE TO OTHER SEMI-ARID ECOSYSTEMS GLOBALLY. THE RESULTS WILL ALSO PROVIDE THRESHOLDS AND CAPABILITIES OF FUTURE NASA LIDAR MISSIONS (E.G. GEDI AND ICESAT-2) AND AIRBORNE EFFORTS TO CONSTRAIN SWE AND RUNOFF MODELS (E.G. SNOWEX ASO UAVSAR).