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|Data by Research Category|
Dataset: Biodiversity plant response, Summer 1999
Pilot study to examine feasibility of measuring individual species response to competing vegetation removal
The experimental area is the `Biodiversity Site' a 250 m x 250 m area located on the NMSU Chihuahuan Desert Rangeland Research Center, immediately northeast of the intersection of the Summerford powerline road and the road running along the southern boundary of the Jornada Experimental Range and the CDRRC. The area was gridded into 25 m x 25 m plots; because of some existing environmental gradients (the area slopes to the east, and mesquite abundance varies from north to south) blocks were established and treatments were randomly assigned to plots within blocks.
field data sheetsMethods:
Ten random individuals of eight plant species were measured. The species of interest were the two most dominant species in each of four classes: shrubs (Larrea tridentata and Flourensia cernua), sub shrubs (Xanthocephalum microcephalum and Zinnia acerosa), succulents (Yucca baccata and Opuntia violacea), and perennial grasses (Muhlenberiga Porteri and Dasyochloa pulchella). Forty-eight plots were surveyed; the plots were divided into six sections of eight plots each. Each section contained a control plot and seven plots that had received a specific removal treatment. The treatments consisted of: the removal of all shrubs; removal of all sub shrubs; removal of all perennial grasses; removal of all succulents; removal of Larrea tridentate, Zinnia acerosa, Yucca baccata, and Muhlenberiga Porteri; removal of Prosopis glandulosa, Zinnia acerosa, Yucca baccata, and Muhlenberiga Porteri; or remove all subordinates of each class, everything except Larrea tridentate, Zinnia acerosa, Yucca baccata, and Muhlenberiga Porteri. The plants to be measured were selected from a random number table after first performing a rough count to determine the number of individuals in the plot, except for Dasyochloa pulchella which was extremely abundant in most plots. For this species the plot was subdivided into 25-5 meter square sub plots, the sub plot to be sampled was then selected from the random number table and the individual plant was chosen within the plot by one member of the team turning their back to the sub plot and flipping a coin over their shoulder while the other member of the team watched to see where the coin fell, the nearest plant was then measured. For all other species one member would hold the numbers to be sampled while the other member of the team counted off the plants while walking around the plot, when a plant to be measured was called the counting was stopped while the individual plant was measured. Three measurements were taken on each plant: first the longest diameter of the canopy, followed by the longest perpendicular diameter, and the height from the highest part of the canopy to the ground immediately below.
Analysis of variance approach tolook for differences among treatments.