Satellite Evidence of Phenological Differences Between Urbanized and Rural Areas of the Eastern United States Deciduous Broadleaf Forest |
| |
Authors: | Michael A White Ramakrishna R Nemani Peter E Thornton Steven W Running |
| |
Institution: | (1) Department of Geography and Earth Resources, Old Main Hall 5240, Utah State University, Logan, Utah 84322-5240, USA , US;(2) NTSG/Forestry, University of Montana, Missoula, Montana 59812, USA , US;(3) National Center for Atmospheric Research,, Climate and Global Dynamics Division, Boulder, Colorado 80307, USA , US |
| |
Abstract: | We used a 10-year record (1990–99) of composited and cloud-screened reflectances from the Advanced Very High Resolution Radiometer
(AVHRR) to test for phenological differences between urban and rural areas in the eastern United States deciduous broadleaf
forest (DBF). We hypothesized that well-documented urban heat island effects would be associated with alterations in temperature-sensitive
vegetation phenology. Our objectives were thus (a) to investigate possible differences in the start of the growing season
(SOS) and end of the growing season (EOS) between the urban and DBF land covers, (b) to investigate related differences in
greenness amplitude and fractional cover, and (c) to develop a generalized additive model (GAM) to predict the spatial variation
of observed differences. By analyzing individual 1° latitude by 1° longitude blocks, we found that, on average, urbanization
is associated with a growing season expansion of 7.6 days. Most of this effect is caused by an earlier SOS in urban areas.
In all cases, urban regions had lower fractional cover and greenness amplitude. The GAM model failed to produce a viable model
for differences in EOS, probably because it is dominated by photoperiod controls with only a minor temperature impact. SOS
differences were predicted with an accuracy of about 2.4 days, with a GAM consisting of smoothed functions of mean annual
average temperature, urban fractional cover, and the urban vs DBF greenness amplitude difference. We speculate that evidence
of a phenological response to warming indicates that global warming, without reduction in DBF vegetation cover and greenness
amplitude, may increase carbon sequestration in mesic deciduous forests.
Received 6 June 2001; accepted 23 October 2001. |
| |
Keywords: | : phenology urbanization urban climate Advanced Very High Resolution Radiometer (AVHRR) normalized difference vegetation index (NDVI) deciduous broadleaf forest |
本文献已被 SpringerLink 等数据库收录! |
|