Reconstructing Late Holocene Climate through Tree-Ring Analysis of Siberian Larch: Altai Mountains, Western Mongolia

Abstract

Abstract

Dendroclimatology utilizes tree-rings to reconstruct past climate. Tree-ring growth is related to limiting growth factors, which can be either internal (biologic) or external (environmental or climatic). A good tree ring record for climate reconstructions is one that is sensitive to its external surroundings, one that records annual changes in climatic parameters such as temperature and precipitation within its annual growth rings. Siberian larches (Larix siberica) in the Altai Mountains of Western Mongolia are examples of such stressed trees. Larch forests are not ubiquitous in the region, suggesting that they are at the limit of their environmental extent and are expected to be sensitive to changes to climate patterns and periodicities. This study attempts to extend paleoclimate records beyond geographically and temporally limited meteorological data for the Altai Mountains, a NNW-SSE trending mountain range along the western border of Mongolia. Studying the climatic patterns of Mongolia prior to instrumental data puts recently observed changes into a broader climatic context. Tree cores were collected from two small larch forests, both occurring on north-facing slopes and at elevations of 2400 to 2900 m. A total of 34 cores were recovered, yielding a 425-year chronology (A.D. 1584). Based on positive correlations with summer temperatures (June through August), this chronology was used as a summer temperature paleoclimate proxy for Mongolia s Altai Mountains and was related to larger climatic systems such as ENSO.