Detecting dryness and wetness signals from tree-rings in Shenyang, Northeast China

For drought and flood forecasting, it is critical I hat we understand regional rainfall patterns as well as their potential underlying forcings, particularly in urban regions with greater long-term anthropogenic influences compared to rural areas. To achieve this, three Chinese pine (Pinus tabulaeformis) tree-ring width chronologies were developed from the metropolitan, suburban, and rural sites near Shenyang city of Northeast China and used to study regional dryness and wetness variability in the past 232 yr. January-May precipitation (1771-2002) was successfully reconstructed from the tree-rings, although urban factors caused a slightly reduced response of the tree-rings to precipitation. Our reconstruction captures certain local rainfall variability and dryness/wetness signals, such as three unusually dry decades (1920s, 1850s and 19605), an unusually dry half-century (1850-1899) and some significant cycles (2-8 yr and similar to 20 yr) associated with them. It also reveals a relatively equal number of dry/wet events (38.79% wet years versus 35.78% dry wars) and a recent drying trend. Our study also indicates the feasibility of using urban tree-rings to reconstruct dry/wet patterns in city environments. (C) 2011 Elsevier B.V. All rights reserved.