In order to better understand the life history of Ocotillo, a re-sampling of Ocotillo plants originally marked and studied in 1991 was done in the southeast corner of the Sevilleta National Wildlife Refuge. All plants measured in 1991 were re-censused and re-tagged with new numbers. Measurements of plant height and branch number were repeated along with measurements pertaining to overall plant size.
To compare Sevilleta Ocotillo populations with the population from 1991, documented in SEV054. The purpose of the study is to find out how the groups of Ocotillo measured in 1991 have changed with respect to size (due to growth) and number. We are quite interested in looking at recruitment in the different groups because of geographical differences (soil, sunlight differences) between sites. Our hypothesis is that plants that can be re-identified will have increased in size since 1991. We also expect there to be recruitment in the groups of plants sampled, but that this could vary from site to site.
We looked for plants with metal number tags given to them in 1991(#1-500), we recorded this number if it could be located, then placed a new metal number tag on the plant(#501-1199). Plants that had lost the 1991 tag were measured and given a new tag. Plants too young to have been measured in 1991 were also tagged and measured. Using a tape measure height and width of the base of the plant (diameter of base) measurements were made. The number of branches at the base of the plant and the number of branch tips were counted. The number of reproductive stems was determined by counting stems with evidence of flowering in that or a previous year. The proportion of dead stems was estimated as a function of the total number of stems on the plant. Plants at the periphery of each group or population were marked by GPS as well. Measurements from 1991 that were not repeated in 2003 were: "Population #" this was determined to be an arbitrary designation by Ms. Redfern. "stems" was determined to be confusing and contradictory when combined with other measurements made in 1991. "buds" ; "flowers"; "fruit", all three were left out because it was decided a measure of reproductive stems present would be more informative in regard to reproduction within the groups of plants. "leaf" was not measured because leaves can come out many times a year as a function of precipitation. "dying" was instead measured as proportion of dead stems present on the plant. Dead stems on a plant do not indicate that the plant is dead or actively dying."#flowering stems" was measured as reproductive stems in 2003.
There are a number of plants sampled in 2003 that were not matched up to plants from 1991. There are also some plants that are presumed new since 1991, and therefore have no 1991 number. Sample 681 from 2003 was recorded 2 times. This error was not resolved.It is important to note that not all measurements made in 1991 were repeated in 2003. This was because it was decided that a number of these measurements were not important given the ammount of time that had passed between the two measurement periods, and the life history of the plant. Also, in 2003 measurements were made that were not done in 1991. It was felt that measurements would be more informative in the long term for life history and demography of Fouquieria splendens.
Additional Study Area Information
Study Area Name: South Gate
Study Area Location: Valle del Ojo de la Parrida - about 2km north of the south boundary on the east side of the refuge
Elevation: 1538 m