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EES : EES Seminar (effects of gw on trees) 7/18
 投稿日時: 2019-07-12 14:57:30 (578 ヒット)
EES

The Environmental Earth Science Seminar will be held as follows.

Location: D101 in GSES
Date and Time: 16:30-18:00 on July 18th (Thu)
Speaker: Marc Abrams (Department of Ecosystem Science and Management Penn State University)

Title: The impact of global change on tree species growth and dominance in the eastern U.S.

Abstract: Global change processes, including climate and natural and anthropogenic (land-use) disturbances have profoundly impacted tree dominance and growth rates worldwide.  To help decipher the relative importance of various drivers of forest change tree species/genera were partitioned into temperature, shade tolerance, and pyrogenicity classes and applied to comparative tree-census data.  We examined changes during the Euro-American period (ca. 1500 to present), which spans two major climatic periods, from Little Ice Age and the Anthropocene. We found that most tree species and age classes exhibited increasing basal area increment (BAI) and/or ring width index (RWI) in recent years.  This is particularly unusual for trees in the older age classes that we expected to have declining growth in the latter years, as predicted by physiological growth models.  There exists an inverse relationship between growth rate and increasing age class.  The oldest trees within each species have consistently slow growth throughout their lives, implying an inverse relationship between growth rate and longevity. Younger trees (< 60 years of age) within each species are consistently growing faster than the older trees when they were the same age resulting from a higher proportion of fast-growing trees in these young age classes. In contrast, changes in tree dominance were not highly consistent with warming. Instead, post-European settlement disturbance regimes mostly overrode climate signals across the eastern US. In the north, intensive and expansive disturbances resulted in the ubiquitous loss of conifers and a large increase in Acer, Populus, and Quercus in northern hardwoods, whereas to the south, these disturbances perpetuated the dominance of Quercus. Mid-twentieth century fire suppression led to large increases in Acer in the latter case, often leading to significant warm-to-cool shifts in temperature class. These series of studies helped elucidate the wide spread and profound impacts of global change on trees and delivered some unexpected results. The reasons for increasing tree growth in the study region and the main drivers of forest change will be discussed, including the climate-disturbance debate.

If you have any question regarding this seminar, please feel free to contact Shiro Tsuyuzaki (tsuyu@ees.hokudai.ac.jp).

Thank you for reading.
See you in D101 by 16:30 on July 18th (Thu).
Best,
ST

 



Graduate School of Environmental Sceince, Hokkaido University