Thermal ecology of summer-blooming Mediterranean thistles

A study was undertaken between 2020-2024 on the thermal ecology of flower heads (capitula) of 15 species of summer-blooming species of Asteraceae, tribe Cardueae, from hot-dry habitats in the southern Iberian Peninsula. Temperature inside (<i>T</i>_in) and outside (<i>T</i>_out) capitula were assessed under natural field conditions by two complementary sampling and measurement procedures, which provided information on the relationships between the two temperatures at the levels of individual capitula ("continuous recording") and local plant populations ("instantaneous measurements"). Baselines for the<i> T</i>_in–<i>T</i>_out relationship in absence of physiological activity were obtained by exposing fast-dehydrated capitula to a broad range of ambient temperatures. To assess whether capitula of summer-flowering Asteraceae defined a distinct thermal layer in the summer environment, the distribution of capitula in relation to the ground was quantified. Bees visiting capitula were watched and temperature of the air beside the visited capitulum (<i>T</i>_out) was measured.This data repository consist of the following 6 files:<b>inert.capitula.csv</b><br>Delimited text file containing <i>T</i>_in and <i>T</i>_out temperature measurements taken on experimental, dry flower heads of 9 species exposed to different ambient temperatures in the field. Variable names are in the first row of the file.<br><b>instant.measures.csv</b><br>Delimited text file containing <i>T</i>_in and <i>T</i>_out temperature measurements taken on natural, living flower heads of 14 species exposed to natural field conditions ("instantaneous measurements"). Variable names are in the first row of the file.<br><b>continuous.measures.csv</b><br>Delimited text file containing <i>T</i>_in and <i>T</i>_out temperature measurements taken continuously on natural, living flower heads of 12 species exposed to natural field conditions ("continuous measurements"). Variable names are in the first row of the file.<br><b>capitula.height</b><br>Delimited text file containing measurements of the height above the ground (cm) of the capitula of 11 species. Variable names are in the first row of the file.<br><b>bee.visits</b><br>Delimited text file containing measurements of air temperature beside flower capitula being visited by bees. Self-explanatory variable names are in the first row of the file.<br><b>Script.R</b><br>R script to analyze the data