DOI: 10.5061/dryad.dr7sqv9vk
title: Vertical stratification collapses under seasonal shifts in climate

description: Aim: Tropical forests are vertically complex, and offer unique niche
 opportunities in the form of climate-, habitat-, and resource-gradients
 from ground to canopy. Rainforest species organize within this vertical
 spatial gradient and recent macro-ecological research suggests that the
 highest levels of vertical stratification occur in structurally complex
 and climatically stable tropical rainforests. Yet, patterns of verticality
 are typically derived across latitude, linking annual precipitation
 regimes to canopy utilization and vertical stratification of communities
 in space. However, although the tropics are not thermally variable, they
 do have strong seasonality in rainfall—a temporal component that is missed
 in macro-scale studies. We hypothesise that verticality of ecological
 communities responds to seasonality in climate, particularly rainfall.
 Location: Sierra Llorona, Colón Province, Panama. Taxon: Amphibians.
 Methods: We performed 121 ground-to-canopy surveys across the wet and dry
 seasons for amphibians. We calculated species specific and community wide
 vertical height and abundance shifts between seasons, and separately test
 the importance of vertical height and season on the vertical distribution
 of species.   Results: Our results show a clear downward
 shift of 5 m in height in amphibian communities from the wet season to dry
 season. We also observe significant changes in species composition across
 vertical strata in both seasons, driven by nestedness in the dry season
 (loss of species over height), and genuine turnover in the wet season
 (loss and addition of species over height). Main Conclusions: The
 exploitation of canopy microhabitats and resources in the wet season
 resulted in complex patterns of stratification, whereas drying flattened
 the distribution and simplified the composition of arboreal communities.
 As such, pattern and process in the vertical dimension is not static in
 time but rather exists as a dichotomy with inverse patterns between wet
 and dry seasons. Complex, multidimensional distributions of diverse
 rainforest communities can be simplified by climatic constraints—an
 important consideration as anthropogenic climate change increases the
 magnitude of seasonal swings in temperature and precipitation.
description: <strong>Study area</strong> In central Panama, we surveyed an Isthmian-Atlantic Moist Forest located within the Esteban Alphonso Lee Natural Reserve (Lat 9.358555 : Lon 79.7029; 499m a.s.l), which borders the Chagres and Portobelo National Parks. Here, we focused our sampling in older growth areas, with primary canopy tree species including <i>Cedrela odorata</i>, <i>Vatairea erythrocarpa</i>,<i> Dipteryx oleifera</i>, <i>Manilkara zapota</i>, <i>Carapa guianensis</i>, <i>Ficus insipida</i>, and <i>Anacardium excelsum</i>. Our sampling area was confined to an altitude range of 333 – 473m a.s.l (Figure S1).  <strong>Vertical stratification of amphibians </strong> We surveyed for frogs during the wet season (April – December) and dry season (January – March; Figure S2). Using survey methods in Scheffers et al. (2013) and Basham et al. (2019), we conducted vertical, ground-to-canopy surveys for amphibians, with each survey centred on a single canopy tree. Tree selection was randomized; however, each tree had to meet safety standards for arborist single-rope climbing (Jepson, 2000). We did not limit our selection by tree species, and were only limited in selection by safety concerns. We surveyed 45 trees for amphibians in the wet season, and 43 trees in the dry season, totalling 46 trees (Figure S1) (Panama Ministerio de Ambiente Permit SE/A-26-2018). Of trees surveyed in the wet season 4 were not resampled in the dry season and 1 tree surveyed in the dry season was not resurveyed in the wet season. Trees were surveyed on 1 - 3 occasions in each season resulting in 66 wet season surveys and 55 surveys in the dry season. For each tree we surveyed for 10 minutes at the ground, understory (2-4m), sub-canopy (approx. half the maximum height climbed), and canopy (maximum height climbed), with a 20 min roaming survey between the strata totalling to 60 minutes. The 10 minute ground survey consisted of searching through leaf litter and ground habitat in a 4 x 4 m area to standardise to the same search area available during climbing. In above-ground surveys, we searched for arboreal amphibians in tree holes, moss, epiphytes and other microhabitat structures (Heyer, Donnelly, Foster, & Mcdiarmid, 1994), and measured the height above ground of each individual using a laser distance metre (Leica Geosystems, Leica Disto D2; http://www.leica-geosystems.ca). <strong>Vertical stratification of climate</strong> Temperature loggers (Onset, HOBO- Pendant; https://www.onsetcomp.com/products/ data-loggers-sensors/temperature) were installed in sets of three per tree. One was hoisted into the canopy &lt; 20 m, a second was hung in the understory at 2 m, and a third was placed 7 cm below the level of the soil. Each pendant was installed in a PVC pipe to protect it from direct sunlight and rain. We installed three arrays in August 2017 and collected the data in August 2018. From this data we gathered daily mean, maximum and minimum temperature. Rainfall data were sourced from the Agua Clara meteorological station (Meteorology and Hydrology Branch, Panama Canal Authority, Republic of Panama; Figure S1).
description: <strong>Data usage statement</strong>
 This data was collected by the Scheffers Lab at the University of
 Florida at great cost of effort and resources. If downloaded for use in
 publications we would appreciate a notification on its usage and would be
 glad to discuss potential research avenues and collaborations. Please use
 this email for contact : brett.scheffers@ufl.edu.
 <strong>Surveys</strong> This tab
 contains data relating to each sampling occassion, consisting of a
 vertical transect located on a tree. Tree, Season, and Date columns can be
 used to identify the sampling regime for each tree and each season.
 Location can be determined by the longitude and latitude columns which are
 included. Tree height, and the height to which the tree was surveyed are
 also included here.
 <strong>Individual</strong> This
 tab contains data relating to the individuals captured and used in this
 study. Tree, Season, and Date columns can be used to link the survey
 information to the individuals collected on each survey. Species names are
 listed, along with the height at which the individual was
 found.  <strong>Rainfall</strong>
 This tab contains data relating to monthly rainfall, sourced from
 the Agua Clara meteorological station (The Panama Canal
 Authority).
 <strong>Temperature</strong> This
 tab contains data relating to maximum, minimum, and mean daily
 temperatures taken from the soil, understory, and canopy. Data were
 collected from three trees, which can be linked to the survey tab which
 contains their coordinates.