Phenological Response of an Arizona Dryland Forest to Short-Term Climatic Extremes

Remote Sensing

Jessica Walker⁴  Kirsten de Beurs³  Randolph Wynne¹  Alfredo R. Huete² 

[1] Department of Forest Resources and Environmental Conservation, Virginia Polytechnic Institute and State University, 310 West Campus Dr., Blacksburg, VA 24061, USA; E-Mail:;id="af1-remotesensing-07-10832">1Western Geographic Science Center, U.S. Geological Survey, 520 North Park Ave., Tucson, AZ 85719, U;Department of Geography and Environmental Sustainability, The University of Oklahoma, 100 East Boyd St., Norman, OK 73019, USA; E-Mail:;Western Geographic Science Center, U.S. Geological Survey, 520 North Park Ave., Tucson, AZ 85719, USA

关键词: dryland forests;    phenology;    STARFM;    data fusion;    Landsat;    MODIS;   

DOI  :  10.3390/rs70810832

来源: mdpi

【 摘 要 】

Baseline information about dryland forest phenology is necessary to accurately anticipate future ecosystem shifts. The overarching goal of our study was to investigate the variability of vegetation phenology across a dryland forest landscape in response to climate alterations. We analyzed the influence of site characteristics and climatic conditions on the phenological patterns of an Arizona, USA, ponderosa pine (Pinus ponderosa) forest during a five-year period (2005 to 2009) that encompassed extreme wet and dry precipitation regimes. We assembled 80 synthetic Landsat images by applying the spatial and temporal adaptive reflectance fusion method (STARFM) to 500 m MODIS and 30 m Landsat-5 Thematic Mapper (TM) data. We tested relationships between site characteristics and the timing of peak Normalized Difference Vegetation Index (NDVI) to assess the effect of climatic stress on the green-up of individual pixels during or after the summer monsoon. Our results show that drought-induced stress led to a fragmented phenological response that was highly dependent on microsite parameters, as both the spatial autocorrelation of peak timing and the number of significant site variables increased during the drought year. Pixels at lower elevations and with higher proportions of herbaceous vegetation were more likely to exhibit dynamic responses to changes in precipitation conditions. Our study demonstrates the complexity of responses within dryland forest ecosystems and highlights the need for standardized monitoring of phenology trends in these areas. The spatial and temporal variability of phenological signals may provide a quantitative solution to the problem of how to evaluate dryland land surface trends across time.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.