Environmental drivers of femaleness of an inter-Andean monoecious shrub

Hetero-and conspecific interactions, nutrient availability,
climate, habitat heterogeneity and disturbances can generate variation
and spatial patterns of femaleness in plants. We assessed whether
year, site, plant size, plant density and canopy area of conspecific
neighbors influenced the expression and spatial aggregation of
femaleness in Croton aff. wagneri, a monoecious shrub from dry
shrublands of the inter-Andean valleys in Ecuador. We georeferenced in
two sites (1,700 and 1,400 m.a.s.l) in five 10´10 m plots, within each
site, the position of each Croton reproductive plant during first part
of flowering season in two years, and measured their height, length
and width. The femaleness index of each plant was determined by the
number of female and male buds and flowers. Plant density was
determined for each plot, along with the number of neighbors and the
summed canopy area of conspecific neighbors (at 1.0, 2.0, and 2.5 m
radius, and the five closest plants) from each focal plant. Croton´s
femaleness at the lower elevation site was greater than at the higher
elevation site and increased with plant size and with canopy of the
closest five neighbors. Soil at the lower elevation site had higher
temperatures and lower water content. Aggregate patterns of femaleness
were found in more plots at the lower elevation site. Our results
indicate that location, plant size and canopies of conspecific
neighbors of Croton can affect femaleness and its aggregation and
support the hypothesis that femaleness can be influenced by
facilitative interactions.
Methods
During the winter season, September 2018 to March 2019, HOBO data loggers S-TMB-M006 and S-SMC-M005 (Onset, USA) were used to measure soil temperature and moisture at a depth of 10 cm, with a sampling interval of 5 minutes at each site which recorded 66932 and 48931 soil temperature and moisture samples for higher elevation site (1700 m) and lower elevation site (, respectively.