Using temperature effect on seepage variations as proxy for phenological processes of basin-scale vegetation communities

The identification of vegetation community growth season is critical for measuring the response of ecosystems to climate change. In this study, vegetation community growth season is measured via fixed-point monitoring of dynamic short-time processes of rock-fissure seepage in the Taihang Mountain Region (TMR). The hydrometeorological data used in the study are obtained from tipping-bucket flowmeters and automated weather stations in the region. Significant differences are noted in daily rock-fissure seepage for different growth seasons. The study shows that during growth seasons, seepage processes in the TMR study area vary with air temperature. Although seepage in the region gradually decreases from 06: 20 to 17: 00 h, it increases from 18: 00 to 06: 00 h. Analysis shows a significant (R-2 > 0.8) negative correlation between seepage and air temperature during growth seasons. For nongrowth seasons, however, seepage processes exhibit near-harmonic variations with air temperature. Also, although seepage during nongrowth seasons gradually increases from 02: 30 to 12: 30 h, it gradually decreases from 13: 30 to 02: 20 h. A significant (R-2 > 0.8) positive correlation also exists between seepage and air temperature during nongrowth seasons. During seasonal crop rotations, however, significant disorders and inconsistencies occur in the seepage processes in the study area. The observed seasonal variations in daily rock-fissure seepages could lay the scientific basis for the adapting trends in crop growth seasons to climate change. Information on this process is critical for crop production and food security for the millions of people in China and beyond. Copyright (C) 2012 John Wiley & Sons, Ltd.