Dr. Jim Speer

ISU faculty member co-authors study on tropical tree growth

Stem growth of tropical trees is reduced in years when the dry season is warmer and drier than normal. This is the main finding of a global tree-ring study co-authored by ISU Earth & Environmental Systems faculty member Jim Speer, recently published in Nature Geoscience led by Wageningen University & Research.

The study is based on a new global network consisting of over 14,000 tree-ring data series from 350 locations across the tropics. The researchers found that the effect of drier and hotter years is larger in more arid or warm regions. This suggests that climate change may increase the sensitivity of tropical trees to climatic fluctuations.

The paper is the result of a collaboration bringing together 94 dendrochronologists and tropical ecologists working with tree-rings in the tropics. Speer has chronologies from Zambia included in the paper and he conducts tree-ring work in Zambia and the Dominican Republic that will help to expand this network.

Quotation Marks Graphic
This is a challenging area and one of the geographical frontiers in dendrochronology.
Dr. Jim Speer
Professor of Geography and Geology

“This makes doing dendrochronology in tropical areas more difficult, although the chronologies that we develop are just as important for understanding global climate changes through time. This collaboration is the first effort to bring together all of the research being conducted in the tropics in tree-ring sciences to examine common patterns as well as data gaps in the network.”