DOI: 10.5061/dryad.5hq26p1
title: Complex long-term dynamics of pollinator abundance in undisturbed Mediterranean montane habitats over two decades

description: Current notions of “pollinator decline” and “pollination crisis” mainly
 arose from studies on pollinators of economic value in anthropogenic
 ecosystems of mid-latitude temperate regions. Comprehensive long-term
 pollinator data from biologically diverse, undisturbed communities are
 needed to evaluate the actual extent of the so-called “global pollination
 crisis”. This paper analyzes the long-term dynamics of pollinator
 abundance in undisturbed Mediterranean montane habitats using pollinator
 visitation data for 65 plant species collected over two decades.
 Objectives are (1) to elucidate patterns of long-term changes in
 pollinator abundance from the perspectives of individual plant species,
 major pollinator groups, and the whole plant community; and (2) to propose
 a novel methodological implementation based on combining a planned missing
 data design with the analytical strength of mixed effects models, which
 allows one to draw community-wide inferences on long-term pollinator
 trends in species-rich natural habitats. Probabilistic measurements
 (“patch visitation probability” and “flower visitation probability” per
 time unit) were used to assess pollinator functional abundance for each
 plant species on two separate, randomly-chosen years. A total of 13,054
 pollinator censuses accounting for a total watching effort of 2,877,039
 flower·min were carried out on 299 different dates. Supra-annual
 unstability in pollinator functional abundance was the rule, with
 visitation probability to flowering patches and/or individual flowers
 exhibiting significant heterogeneity between years in the majority of
 plant species (83%). At the plant-community level, there was a significant
 linear increase in pollinator functional abundance over the study period.
 Probability of pollinator visitation to flowering patches and individual
 flowers increased due to increasing visitation by small solitary bees and,
 to a lesser extent, small beetles. Visitation to different plant species
 exhibited contrasting changes, and insect orders and genera differed
 widely in sign and magnitude of linear abundance trends, thus exemplifying
 the complex dynamics of community-wide changes in pollinator functional
 abundance. Results of this investigation indicate that pollinator declines
 are not universal beyond anthropogenic ecosystems; stress the need for
 considering broader ecological scenarios and comprehensive samples of
 plants and pollinators; and illustrate the crucial importance of combining
 ambitious sampling designs with powerful analytical schemes to draw
 reliable inferences on pollinator trends at the plant community level.
description: Pollinator visitation
 data Raw pollinator
 visitation data for the N = 65 plant species studied. Working.dataset.csv
 
 Characteristics
 of individual plant species Sampling site elevation,
 life form, and corolla type, for individual plant species
 Species.data.csv
 
 R Script
 1 #
 Script 1 # TESTS #1 AND #2 IN TABLE 2 # Section "Individual plant
 species: patch visitation" Script.1.R
 
 R Script
 2 #
 Script 2 # TESTS #3 AND #4 IN TABLE 2 # Section "Individual plant
 species: flower visitation" Script.2.R
 
 R Script
 3 #
 Script 3 # # Section "Visitation probabilities and flowers per
 patch" Script.3.R
 
 R Script
 4 #
 Script 4 # # Section "Supra-annual fluctuations in pollinator
 composition" Script.4.R
 
 R Script
 5 #
 Script 5 # TESTS #5 AND #8 IN TABLE 2 # Section "Community-level
 trends: all pollinators" Script.5.R
 
 R Script
 6 #
 Script 6 # TESTS #6 AND #9 IN TABLE 2 # Section "Community-level
 trends: insect orders" Script.6.R
 
 R Script
 7 #
 Script 7 # TESTS #7 AND #10 IN TABLE 2 # Section "Community-level
 trends: selected genera" Script.7.R