Climate change effects on shrubland carbon dynamics.

Shrubland ecosystems are potential carbon sink and important habitat of many endangered wildlife species. Intensive agricultural activities during the past century coupled with changing environmental factors have heavily impacted global shrubland affecting their carbon sequestration potential and wildlife habitat. In this study, climate change effects on shrubland carbon dynamics were assessed using remote sensing, ecophysiology, and ecosystem process modeling techniques across an environmental gradient of restoring shrublands of Lower Rio Grande Valley, Texas, USA. Shrubland restoration efficacy and effects of climate variability on carbon stored in shrubs were investigated through remote sensing. A canopy identification algorithm was developed and applied to Digital Ortho Quarter Quadrangle images to estimate shrub density, canopy area, and shrub biomass. From this study, I found higher shrub density with lower biomass for naturally regenerated area compared to that of replanted area. I concluded that current effort on native shrub restoration effectively increases carbon sequestration in vegetation biomass. Next, an assessment of five dominant native shrub species was carried out with a month long drought and salinity treatment to assess shrub’s ecophysiological response to climate change and included: Acacia farnesiana, Celtis ehrenbergiana, Forestiera angustifolia, Parkinsonia aculeata, and Prosopis glandulosa. This study showed that shrub species have developed tolerance strategies to cope with soil water stress but the extent can be species specific. Finally using information of remote sensing and ecophysiological studies, ecosystem process modeling was performed using 3-PG model to predict climate change effects on shrubland productivity and habitat conservation of endangered wildlife species. Overall, I conclude that restoration efforts within the study area shows potential for sequestering carbon in tissue biomass and habitat conservation under the influence of current climate, but future climate change is likely to reduce its carbon sequestration potential with the loss of wildlife habitat