The physiology, genetics, and distribution of ponderosa pine species vary with changes in elevation and environmental conditions

Research Issue

A great need exists for collecting data on tree populations as part of a forest indicator and monitoring system.  The information is important to confirm models for predicting climate change effects on individual forest stands.  Current developments in DNA sequencing methods allow new possibilities for basic research on plant responses to environmental stress including growth, water usage, and cross breeding to form hybrids – and Ponderosa pine species are prime candidates for study.

Our Research

In the desert southwest, significant variations in moisture and temperature occur along steep gradients in elevation.  Notably, the endemic ponderosa pine species vary with changes in elevation and the differences in elevation are repeated throughout the ranges of the species.  The long-term goal of the study is to provide a foundation for future regional studies of species range limitations by water or temperature stress.  This information is vital to further increase our understanding of the movement of tree species within and between climate zones.  Our objective is to study stark transitions in elevation for two species of ponderosa pine differing in habitat preference.  Prior to changes in mortality, we propose to sample adult and seedling age classes of each species at three locations to compare their growth, physiology, and genetic diversity.  Study sites include north and south facing slopes of the Santa Catalina Mountain range where the species co-exist and are potentially hybridizing.  Two of the mountains have experienced fire in the last decade providing us a tremendous opportunity to study the naturally regenerating seedlings of the surviving parental trees.

Expected Outcomes

The research will be of fundamental value to physiologists and geneticists examining the stress response of plant species.  In addition, the conclusions will be useful to land managers for the study aims to describe in detail the spatial distribution of the two pine species.  Such knowledge will provide viable options for long-term improvement of reforestation efforts and sustainable management of natural areas in the desert southwest.

Research Participants

Principal Investigator

• Paula Marquardt, US Forest Service Northern Research Station - Research Plant Geneticist

Research Partner

• Frank W. Telewski, Michigan State University - Professor of Plant Physiology