Abstract
Frozen ground may regulate the phenological shifts of dry and cold grasslands at the southern edge of the Eurasian cryosphere. In this study, an investigation based on the MODIS Collection 5 phenology product and climatic data collected from 2001 to 2009 reveals the diverse responses of grassland phenology to interannual climate variability over various frozen ground regions in Mongolia. Compared with middle and southern typical steppe and desert steppe, the spring (start of season; SOS) and autumn (end of season; EOS) phenological events of northern forest steppe with lower air temperature tend to be earlier and later, respectively. Both the SOS and EOS are less sensitive to climate variability in permafrost regions than in other regions, whereas the SOS of typical steppe is more sensitive to both air temperature and precipitation over sporadic permafrost and seasonal frozen ground regions. Over various frozen ground regions in Mongolia; the SOS is mainly dominated by the prior autumn precipitation, and frozen ground plays a vital role in storing the precipitation of the previous autumn for the subsequent grass green-up. The EOS is mainly dominated by autumn air temperature. These findings could help to improve phenological models of grasslands in extremely dry and cold regions.
Highlights
Vegetation phenology has been of increasing interest because it is sensitive to climate warming [1,2,3].Long term in situ records and satellite remote sensing observations have revealed that spring and autumn events of temperate vegetation over the Northern Hemisphere have advanced and been delayed by a couple of days because of global warming, respectively, depending on the locations and datasets used [4,5].Phenology shifts will in turn affect the climate through biogeochemical and biophysical effects [6]
Across Mongolia, the start of season (SOS) of grasslands ranges from early April to late May, and the end of season (EOS) of grasslands ranges from early September to middle October (Figure 2)
This study focused on grassland community rather than specific grass species; the Moderate-Resolution Imaging Spectroradiometer (MODIS) land surface phenology (LSP) data could satisfy the investigation into the relationship of grassland phenology shifts and interannual climate variability in this study
Summary
Phenology shifts will in turn affect the climate through biogeochemical and biophysical effects [6]. Vegetation phenology is controlled by many factors that differ with climate [2]. In humid regions, it is mainly controlled by the degree of winter chilling, photoperiod, and temperature [2,10,11]. It is mainly controlled by the degree of winter chilling, photoperiod, and temperature [2,10,11] In arid regions, it is mainly controlled by air temperature and precipitation (or soil moisture) [12,13,14,15,16,17,18]
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