Long-term study of tree cholla demography in the Los Pinos mountains, Sevilleta National Wildlife Refuge

This study was initiated in 2004 by TEX Miller to quantify
individual-level demographic rates of tree cholla cacti
( Cylindriopuntia imbricata ) at the Sevilleta
National Wildlife Refuge, Socorro Co., NM. This data package spans
2004-2018, though the study is maintained through the present. In each
year, censuses were conducted over several days in the last week of
May and/or the first week of June. Individuals were marked with
aluminum tags and tracked longitudinally through time, with annual
measures of survival, size, reproductive output, and interactions with
insect herbivores and mutualists (extra-floral nectar-feeding ants).
For the years 2004-2008, plants were grouped into spatial blocks (T1,
T2, T3) lacking defined boundaries. Beginning in 2009, the study
design changed to 30m x 30m plots (Plots 1-8) with an entirely new
cohort of individuals that does not overlap with the 2004-2008 data.
From 2009 onward, plots were searched each year and new plants were
added to the census as they were discovered. Seedlings typically
require several years of growth before they are detectable in our
census, so counts of new plants in a given year do not necessarily
reflect recruitment in that year. The data frame is set up such that
one row is a transition year (May of year t to May of year t+1) for
one individual; this means that all but the first and last years’
observations occur twice, once as the start of a transition year and
once as the end.