Abstract Detail

Ecophysiology

Marquardt, Paula E. [1], Jennings, Shane [2], Thurston, Ginger [2], Telewski, Frank W. [3].

Dendrochronology and Climate Distinguishes the Sky Island Pines.

Background: Dendrochronology or the analysis of tree rings plays a major role in the study of plant growth responses to climate and other environmental factors. In the Desert Southwest, the variation in ring-width is more dependent on precipitation than temperature. The climate of the Southwest is warm and semiarid, with two dry seasons and two rainy seasons – the summer monsoon and winter precipitation. Our research focused on using two taxa of ponderosa pine as a model system to study changes in woody plant growth based on habitat preference, primarily water availability. The high elevation ponderosa pine forests of the Santa Catalina Mountains consist predominantly of two partially sympatric species, the well characterized five-needled Pinus arizonica, and the mixed needled Taxon X. The main question of the study was to identify the environmental factors determining the distribution of the two species. Methods: Trees of both taxa were cored where the two species overlap (2500 m + 60 m). We applied the technique of cross dating using skeleton plotting to identify distinct patterns of growth in the annual rings of trees, matched growth-ring widths among many wood samples, and accurately identified the calendar year of formation for each tree ring. Data were collected at the transition zone along two south-facing slopes for needle number and tree-ring widths. The objective of the study was to apply dendrochronology to interpret annual ring-widths for the two ponderosa pine species with regard to climatic variables of temperature, precipitation, elevation, and palmer drought severity index which set limits to growth. Results: We showed that the response function of P. arizonica, sampled on a site near its higher (and moister) elevation limit, correlated strongly with summer and spring precipitation, with no correlation with winter precipitation. Surprisingly, the response function of Taxon X, sampled on a site near its arid and lower elevation limit, also correlated most strongly with the monsoon rains in summer; the correlation with winter precipitation was weak. Conclusion: These findings suggest that spring precipitation events can distinguish the two species. Data will be presented also on temperature responses of the two species, and for response differences between age classes and between sites.

Related Links:
http://www.nrs.fs.fed.us/disturbance/climate_change/climate_change_and_ponderosa_pine/

1 - USDA Forest Service, 5985 Hwy K, Rhinelander , WI, 54501, USA
2 - Michigan State University, Plant Biology, 612 Wilson Rd, East Lansing, MI, 48824, USA
3 - Michigan State University, Plant Biology, 612 Wilson Road, East Lansing, MI, 48824, USA

Keywords:
Ponderosae
limiting factor
drought
distribution.

Presentation Type: Oral Paper:Papers for Topics
Session: 25
Location: Salon 16/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 8:00 AM
Number: 25001
Abstract ID:552
Candidate for Awards:None