Native vegetation is the key resource upon which rangelands are built, and restoring rangeland ecosystems are one of the most critical challenges facing rangeland managers today. This experimental fire research project, in collaboration with the USFWS and the Sevilleta LTER, is intended to provide FWS and other land managers of southwestern grasslands and rangelands with information about vegetation recovery following fire under different seasonal conditions and burning treatments. This experimental research will enable the FWS to more effectively set project objectives for prescribed burning on the Sevilleta NWR to benefit not only wildlife habitat, but to better align the timing and intensity of fire to benefit the reestablishment of the dominant native grama grasses Bouteloua eriopoda and B. gracilis. Since its creation in 1973, management has been devoted to restoring the Sevilleta NWR to the natural conditions that might have been seen around the turn of the century. The Sevilleta NWR is an ideal place for research because climatic conditions, plant species composition and net primary production following wildfire have been well documented by the Sevilleta LTER. Additional experimental research is needed, however, to better inform managers about the timing and use of fire as an ecosystem restoration and management tool. Data collection and analysis will be continued by the Sevilleta LTER beyond the requested funding period.
The goal of this experiment is to determine the effects of dormant season burns on plant community composition and aboveground standing crop in desert grassland. Experimental burning treatments and sampling sites are located in a long-term unburned area of Chihuahuan desert grassland dominated by B. eriopoda. The experimental design is completely randomized, with four treatments replicated five times. Treatments are spring (dormant season), summer (growing season) and fall (dormant season) fires and unburned. This experiment was initiated in June 2007 with one year of pre-treatment data. The first set of prescribed fires was carried out starting in fall 2007 (November) with the spring (March) and summer (June) fires in 2008. Replicates are randomly assigned to 20 .24-ha plots. Ten meters of unburned area separates the plots. Seasonal fire treatments were repeated in November 2016, April 2017 and June 2017, and the control plots remaining unburned.
Plant community composition and percent cover of individual plant species is monitored semiannually (spring and fall) in ten permanently marked 1m2 subplots in each treatment plot (n=200). Aboveground net primary production is estimated periodically by harvesting all vegetation in 10 randomly located 0.1m2 subplots in each treatment plot in each plot at the end of the growing season, drying and weighing. Other response variables measured occasionally include several soil parameters (moisture, organic matter content, and field available nitrogen (NO3-N and NH4-N)).
Data were visually checked to ensure accuracy.
Species composition was sampled semiannually (spring and fall) each year. Prescribed fires occurred in November 2007, March 2008, and June 2008. Seasonal fire treatments were repeated in November 2016, April 2017 and June 2017, and the control plots remaining unburned.