Adapting Pinelands National Reserve to climate change: tree-rings as tools to predict adaptability in seed source tests




Use of Long Term Experimental Forest Provenance Trials for Selection of Future Forests: Tools to Predict Forest adaptation to Climate Change

- Funding through the USFS Northern Research Station

Research Objectives:

Our objective is to help land managers make the correct decision on pitch pine provenances for restoration in the Pinelands National Reserve after disturbances, and to provide a tool that can be extended to other species and other ecosystems. We will use the trend in annual growth increments and earlywood/latewood ratios in a range of seed sources to recommend which seed sources of pitch pine are suited for restoration and reforestation in current and future climates – as contrasted to the local seed source, which was adapted to past climates - in the Pinelands National Reserve. The goal is to improve management decisions to mitigate the effects of climate change and to protect ecosystem function while demonstrating a transferable decision support tool.

Background Local tree populations may not be best suited for optimal carbon fixation under current climactic conditions because of well documented warming trends. Given future projected climate change, it may be more effective to reforest with genetic material from different geographic regions, which may be better adapted to warmer temperatures. Restoration with appropriate provenances adapted to new climate stresses will enhance forest health, carbon sequestration, and ecosystem sustainability, while maintaining historic species community structure, and protecting against invasive species (Ledig and Kitzmiller, 1992).

When planted, progeny of local seed sources were adapted to the climate at New Lisbon, and progeny from further afield were less adapted. Annual increment would reflect the degree of adaptation. The greater the difference between climate at the origin and at the planting site, the greater the differences in growth between the local and the introduced progeny in a constant climate.

However, with global warming, southern progeny should become better adapted to the planting site and the locals, less adapted. We predict that this will be reflected in a trend toward increasing increment for the southern progeny relative to the locals. Because heat sum is the signal for initiation of growth in the spring and photoperiod is the signal for cessation of radial growth in the fall (Kramer and Kozlowski 1960, Larson 1957), in a warming climate the local progeny will begin growth earlier but cease growth at the same time (i.e., at the same photoperiod) so their earlywood/ latewood ratio should increase. We expect a decrease in the earlywood/latewood ratio in southern progeny because they will produce more latewood in an extended fall growing season. The trend for a provenance to the immediate south of the planting site may be one that increases for a period of years, reaches a maximum, and then declines as climate "moves" past the provenance's adaptive peak.

It has been widely demonstrated that heat sum is the signal for initiation of growth in the spring and photoperiod is the signal for cessation of radial growth in the fall. Winter chilling is also an important factor in date of growth initiation (Worrall 1969, Zhang et al. 2007). In experiment after experiment, seed source or provenance tests, like the one at New Lisbon, have shown these predictable patterns (Morgenstern 1996). However, use of this valuable information in tracking changes in response to climate change has not been applied to choice of seed source. Because low temperatures or drought adversely affect shoot extension and leaf development and, thus, lower the level of diffusible auxin, they result in the formation of smaller or radially flattened tracheids of the latewood type (Zimmerman and Brown 1971). Therefore, earlywood/latewood ratios must be adjusted for annual variation in climate.

Typical scene in the provenance study site.

Problem Area

The proposed study applies to RWU-FS-NRS-06 problem area 4, "Climate Change Impacts and Adaptation". This study will directly inform the "facilitated adaptation" program components found in both the WO and R9 Climate Change guidance. Broadly, this work will provide a framework for examining how genetic diversity (from a latitudinal gradient) within individual species can be utilized by managers for adapting forests to climate change. This study will both better our understanding of individual species genetic adaptability and also provide a transferable framework for transferring this methodology to other previously established, long-term, seed source experiments. The results of this study will also be directly applicable to recommendations on pitch pine provenances for restoration in the Pinelands National Reserve after disturbances. For more information on the Pinelands National Reserve try here and here.

Orienting to the 1974 experimental design proved to be a steep challenge.


Kramer, P. J. and T. T. Kozlowski. 1960. Physiology of trees. New York: McGraw-Hill.

Larson, P. R. 1957. Effect of environment on the percentage of summerwood and specific gravity of slash pine. School of Forestry Bulletin no. 63. Yale University, New Haven, CT. 78 p.

Ledig, F. Thomas and J. H. Kitzmiller. 1992. Genetic strategies for reforestation in the face of global climate change . Forest Ecology and Management 50:153-169.

Morgenstern, E. K. 1996. Geographic variation in forest trees: genetic basis and application of knowledge in silviculture. University of British Columbia press, Vancouver, BC. 209 p.

Worrall, J. and F. Mergen. 1967. Environmental and genetic control of dormancy in Picea abies. Physiologia Plantarum 20: 733-745.

Zhang, X., D. Tarpley, and J. T. Sullivan. 2007. Diverse responses of vegetation phenology to a warming climate. Geophysical Research Letters 34: L19405. 5 p.

Zimmerman, M. H. and C. L. Brown. 1971. Trees structure and function. Springer Verlag, NY.