Native Plant Society of New Mexico Native Plant Society of New Mexico

Peggy De’Scoville, MS candidate in Natural Sciences at New Mexico Highlands University.

Location: Kit Carson Electric Coop Boardroom, 118 Cruz Alta, Taos, NM 87571

DETAILED DESCRIPTION:
Pinyon and juniper vegetation comprise a large part of New Mexico’s wildland urban interface and are affected by thinning treatments which aim to reduce fire hazard but offer few ecological considerations. Since the Hermit’s Peak/Calf Canyon Fire in 2022, New Mexico’s forests have become a national priority for fire mitigation.

The composition of pinyon-juniper forests in San Cristobal of northern New Mexico is being altered through these fire mitigation treatments and the altered composition appears to be intentional. In fire mitigation prescriptions, juniper is last on the list of trees to keep and local foresters claim that juniper is a weed tree, a bias that has been perpetuated for more than fifty years in pinyon-juniper ecosystems, but which carries little scientific weight. Though the ramifications of removing juniper from the PJ systems are not well understood, it seems that this practice is widespread. Juniper trees are the pioneer species. They pave the way for pinyon by creating favorable microsites for pinyon seedlings who in time may become the climax tree. This is the first study in Forest Service Region 3 to document the concentrated removal of juniper from pinyon-juniper systems.

To understand ramifications of this practice, we analyzed pinyon-juniper forests five years post-treatment in San Cristobal, NM, to quantify forest overstory characteristics, understory vegetation, regeneration, pests and pathogens, and mortality in areas thinned with the composition of pinyon to juniper “Intact,” composition of pinyon to juniper altered “Altered,” and un-thinned “Control”. About 72% of the survey plots had their composition altered by more than 15% post-treatment. Our results show no significant differences between Intact and Altered areas for pinyon regeneration density (TPH), regeneration mortality (%), and understory graminoid cover, or dwarf mistletoe rating (DMR). No juniper regeneration was found in the altered treatments, and juniper regeneration was very low in both controls and Intact. The concentrated removal of juniper does not appear to support forest health or resilience. If fire mitigation thinning must be implemented, we recommend maintaining the composition of the woodland to preserve more of the historic range of variability and thus sustain ecological resilience within PJ forests.

BIO: Peggy has lived in Taos for 25 years. After many years in the hospitality industry of Taos, she made the leap to return to school and join the team working to save NM’s forests. In 2021, she earned her associate degree in pre-science from UNM-Taos and in 2023, a Bachelor of Science in Forestry from New Mexico Highlands University. This spring, she will graduate from NMHU with her Master of Science in Natural Sciences – Environmental Science and Management Concentration. Peggy also works as a leñero for the San Cristobal Mayordomo Project, helping to thin the forest to mitigate high-severity wildfire.

Peggy’s undergraduate research involved the effects of winter defoliation on high-elevation conifers in the Santa Fe National Forest by Janet’s looper moth. Peggy has plans to continue research in the PJ of San Cristobal using tree increment cores and carbon isotope discrimination to understand the physiologic effects of concentrated juniper thinning on the remaining trees.