Water Resources Professional Project Reports

Document Type

Technical Report

Publication Date

10-2016

Abstract

This project was designed to understand the potential impacts of climate change on soil moisture and the resiliency of ponderosa pine in the forested region of the Cebolla Canyon watershed (Cebolla), located in eastern New Mexico. Much of the watershed is administered as public domain land by the U.S. Bureau of Land Management (BLM). This project aims to help BLM managers understand how climate change is projected to impact ponderosa pine seedling establishment and mature ponderosa pine productivity in Cebolla.

Current and potential future soil moisture regimes in Cebolla were simulated on three hills using HYDRUS-1D. The soil moisture regimes were compared to those of a ponderosa pine forest (PPF) reference site and a pinyon-juniper woodland (PJW) reference site where measured soil moisture data was available. Soil moisture for all sites was interpreted relative to its θcrit, a site specific soil moisture value that depends on soil properties and the minimum soil-water potential at which ponderosa pine can extract water from the soil. The projection for seedling establishment was measured by the shallow soil moisture which was lower than θcrit more often in Cebolla than the PPF site, indicating that Cebolla soils are drier than ideal for seedlings. Mature ponderosa pine productivity was measured by the deeper soil moisture regime which had over 900 consecutive days out of 1825 below θcrit and became progressively drier as temperatures were increased. The results suggest that ponderosa pine resiliency is low. There are indications that current thinning treatments have sustained ponderosa pine, but the impact of thinning treatments in the future remains uncertain and small changes in θcrit significantly alter the projection of ponderosa pine resiliency. Therefore, a monitoring program is recommended to obtain measured meteorological, soil moisture, and soil water potential data in Cebolla. These data would improve the BLM’s understanding of soil moisture changes and projections for ponderosa pine resiliency as the climate changes.

Keywords

climate change, soil moisture, resiliency, ponderosa pine, Cebolla Canyon, Cebolla Canyon watershed, eastern New Mexico, soil moisture regimes, pinyon-juniper woodland

Comments

A Professional Project Report submitted in partial fulfillment of the requirements for the degree of Master of Water Resources, Water Resources Program, University of New Mexico.

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