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I? . · i> Appendix C FIRE HISTORY OF THE RIO GRANDE NATIONAL FOREST INTRODUCTION Loolc.ing at the landscape of the Rio Grande National Forest (RGNf) reveals that large fires occurred sometime in the past. Walking through the forest reveals even more including evidence of large burned trees in a lower successional stage forest or burned snags in grassy areas where trees never grew again. When did these fires occur? How were they started? Were they started by people, and if so, why? Such questions are not easy to answer but are important in determining the range of variability within specific ecological land unit associations (ELUA's). This document will present a summary of information found in a literature search for locations, dates, and probable causes of some of the larger forest fires. In 1892 it was estimated that 12 percent of tI ,e area in the proposed San Juan Forest Reserve, which included parts of the RGNF, was vegetated in aspen (DuBoiS 1892/. DuBois also said that" all of the Rio Grande side of the range, with the exception of bodies of spruce on the heads of creeks, had been burnt, much of it repeatedly." In 1932 it was estimated that 142,000 acres of the RGNFwas aspen which gives an idea of the extent of early fires (RGNF 1953). REFERENCES TO CLIMATIC CONDITIONS Historic information pertaining to past climatic conditions was found in the literature search. One such document contained a line graph indicating the annual precipitation for Sante Fe, New Mexico from 1850 until 1948 (RGNF 1953) which is attached. The graph indicates that relatively dry conditions prevailed in the years 1850, 1857 to, 1860, 1863,1867,1872,1877, 1879 to 1882, 1889, 1892 to 1894, 1899,1903,1910,1912,1917,1924,1931,1939, and 1943. Another line graph, from 1910to 1948, was compiled from an average of Cumbres, Manassa, Hermit, and Garnett records. A correlation between this graph and the Sante Fe portion of the graph is apparent and can be seen in Figure C-1. Other references to dry conditions indicate that the winter of 1874f75 was dry (Agee 1924). Extreme ~rought was also noted in 1924 and 1931 (RGNF 1953). CAUSES OF FOREST FIRES A number of references indicate that fires were sometimes started by American Indians (Agee 1924, RGNF 1953). Other fires were attributed to sheepmen setting fire to improve forage (Agee 1924) and it was said, "it is safe to say that 75 percent of the fires are set, either accidently or intentionally, by sheep herders" in the early days (DuBois 1892). The vicinity of La Jara Meadows on the Conejcs Peak Ranger District is said to have been burned repeatedly from the 1870's to the 1890's by sheepherders who set C-1 f't.'~""~ ....)0 t" ".. ~ h.