Since 1997 we have been studying conifers at tropical treelines. Volcanoes in Mexico, ranging from more than 4000 m (~14,000 ft) to more than 5500 m (~18,000 ft) in height, offer sites suitable for dendrochronology. Our primary study location is at 3760 m (~12,340 ft) on Nevado de Colima, an extinct volcano next to the actively erupting Volcan de Fuego de Colima.

Considering its location within the North American Monsoon System (NAMS), in the tropics (latitude 19.5°N), and at treeline, Nevado de Colima is an ideal spot for interdisciplinary studies. It is also a permanent plot site where an increasing amount of data on climate, tree growth, insect outbreaks, and other environmental changes are being recorded and analyzed (see list of publications at the end).

An automated weather station has been operating at our study area since May 2001, recording data at half-hour intervals on a number of environmental variables. Several point and band dendrometers were also installed at the site in May 2001, and were maintained for several years (until funding ran out).

In terms of which dendrometers (point vs. band) to use, we found that bark features are very important. If you are dealing with species that have a relatively thin, non-deeply fissured bark, then band dendrometers are probably the best choice. However, for species that have relatively thick, deep-fissured bark, using point dendrometers at stem locations where most of the bark has been shaved off works best. That's because the deep bark (if not removed) greatly amplifies hydration/dehydration changes compared to true changes in stem size related to wood increment.

The following publications are available on the diverse aspects of this project:

• 2010 Biondi, F., and P. Hartsough. Using automated point dendrometers to analyze tropical treeline stem growth at Nevado de Colima, Mexico. Sensors 10: 5827-5844 (ARTICLE in PDF format - about 0.4 Mb).
   
  
• 2010 Biondi, F. and I. Galindo Estrada. Tree-ring evidence for the 1913 eruption of Volcán de Fuego de Colima, Mexico. In: M. Stoffel, M. Bollschweiler, D. R. Butler, and B. H. Luckman (editors), Tree Rings and Natural Hazards: A State-of-the-Art, Series "Advances in Global Change Research" Vol. 41, Springer, New York, pp. 453-464.
   
  
• 2009 Biondi, F., P.C. Hartsough, and I. Galindo Estrada. Recent warming at the tropical treeline of North America. Frontiers in Ecology and the Environment 7(9): 463–464 (ARTICLE in PDF format - about 0.5 Mb; Supplementary Materials in PDF format - about 0.5 Mb).
   
  
• 2008 Hartsough, P.C., S.R. Poulson, F. Biondi, and I. Galindo Estrada. Stable isotope characterization of the ecohydrological cycle at a tropical treeline site. Arctic, Antarctic, and Alpine Research 40(2): 343–354 (ARTICLE in PDF format - about 1.8 Mb)
  
  
• 2005 Biondi, F., P.C. Hartsough, and I. Galindo Estrada. Daily weather and tree growth at the tropical treeline of North America. Arctic, Antarctic, and Alpine Research 37(1): 16-24 (ARTICLE in PDF format - about 0.8 Mb).
  
  
• 2003 Biondi, F., I. Galindo Estrada, A. Elizalde Torres, and J.C. Gavilanes. Tree Growth Response to the 1913 Eruption of Volcán de Fuego de Colima, Mexico. Quaternary Research 59(3): 293-299. (ARTICLE in PDF format - about 0.3 Mb)
  
  
• 2002 Biondi, F. Treeline Dendroclimatology in the North American Tropics. PAGES News 10(1): 9-10. (ARTICLE in PDF format - about 6 Mb)
  
  
• 2001 Biondi, F.. A 400-year tree-ring chronology from the tropical treeline of North America. Ambio 30: 162-166. (ABSTRACT; ARTICLE in PDF format - about 1.4 Mb)
  
  
• 1999 Biondi, F., I. Galindo Estrada, A. Burton, S.E. Metcalfe, D.R. Cayan, and W.H. Berger. A 400-year tree-ring chronology from the North American Tropics. In T.R. Karl (ed.), Proceedings of the 10th Symposium on Global Change Studies, American Meteorological Society, Boston, MA, pp. 161-162. (ARTICLE in PDF format - about 0.4 Mb)

Pictures of trips and fieldwork related to this study are available from the following links:

Assorted Mexico Pictures

Mexico Trip winter break '02-'03