Abstract
Variation in winter temperature is less well understood than in annual and summer temperatures over long timescales, particularly in low-latitude (0–30° N) montane regions with large spatial and topographic heterogeneity. Understanding these variations could be critical for forest manageemnt in these important tree growing regions. We collected tree-ring cores from Yunnan Province in montane southwest China, to determine how winter temperature has varied in the past and to explore its possible drivers in this region. Six highly correlated site chronologies were combined into a long and well-replicated regional composite (RC) chronology. The RC chronology correlated strongest with mean early winter season temperature (EWST) from November to January during 1959–2015. We applied RC chronology to reconstruct EWST from 1653 to 2015. The reconstruction shows five relatively warm historic intervals (1658–1718, 1743–1755, 1771–1791, 1929–1959, and 1995–2015) and cold intervals (1720–1742, 1792–1852, 1860–1883, 1905–1928, and 1960–1994). The 1950s with six anomalous warm seasons and 1980s with five anomalous cold seasons were the warmest and coldest decades, respectively. The EWST reconstruction generally agreed with other winter temperature reconstructions from nearby areas and with historical documents. Atlantic Multidecadal Oscillation (AMO) might be a key forcing of multidecadal winter temperature variations in montane southwest China over the past three and half centuries. Both warm and cold temperature periods coincide with respective positive and negative phases of AMO. Besides, the cold intervals during the nineteenth and twentieth centuries may also have been influenced by large volcano eruptions in low-latitude regions of south and east Asia. Our EWST reconstruction not only improves our understanding of the trends and variations of winter climate history, but also supports planning for resilience in conservation, agriculture, and forestry management in montane southwest China into the future.
Highlights
Winter temperatures are one of the most critical factors for plant growth and forest dynamics (Körner 2003)
We collected tree-ring cores of A. georgei from northwest Yunnan Province to test the suitability of this species for winter temperature reconstructions and to answer two major research questions: (1) how has the winter temperature varied in the past three and half centuries? and (2) what are the possible drivers of winter temperature variation in this region? We present reconstruction and compare it with other reconstructions to enhance the understanding of the winter climate history of this region at long time-scales
The radial growth of A. georgei was significantly correlated with different winter temperature windows from November to April for raw data (Fig. 3a) and first difference data (Fig. 3b) of the chronology and temperature, and with different summer temperature windows from Jun to September for raw data of the chronology and temperature (Fig. 3a)
Summary
Winter temperatures are one of the most critical factors for plant growth and forest dynamics (Körner 2003). They can determine the post winter performance of plant species (Luedeling et al 2011), shape the geographic range of many forest species (Crumpacker et al 2001), and influence. Extended author information available on the last page of the article species composition and production in most regions (Kreyling 2010). Temperature increase due to global warming is more pronounced in winter than that in summer in high-latitude regions and in low-latitude regions with high elevation (IPCC 2014). Compared with summer temperatures, the variations and changing trends of winter temperatures have received little attention and are poorly understood (George 2014; Wu et al 2013)
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