Data from: Vertical niche usage and trait associations in Gabonese amphibians
Data files
May 21, 2024 version files 1.68 MB
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Climate_data.csv
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Individual_capture_data.csv
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README.md
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Traits_scaled_data.csv
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Tree_survey_data.csv
Abstract
Tropical forests are vertically complex, and offer unique niche opportunities in the form of resource, climate, and habitat-gradients from the forest floor to the canopy. Rainforest amphibians organize within this vertical space and the highest levels of vertical stratification occur in structurally complex and climatically stable tropical rainforests. Amphibians have diversified into numerous habitat and climatic niches, which has led to the development of a wide variety of morphological, behavioural, physiological, and reproductive traits. However, a lack of data regarding the vertical niche space used by amphibian species has prevented a nuanced analysis of traits and vertical height. We performed 74 ground-to-canopy surveys for amphibians at Baposso Village, Ngounie Province, Gabon, and describe the vertical stratification patterns of the assemblage in terms of richness, abundance, and species specific vertical niche usage. We analyse the relationships between amphibian traits with vertical height using linear mixed effects models, finding strong support that frogs with bigger toes in relation to their length access greater height in the canopy. We also see differences in the vertical heights of species according to their reproductive modes, highlighting the importance of reproductive mode diversity for the vertical stratification of amphibian assemblages.
README: Data from: Vertical niche usage and trait associations in Gabonese amphibians
This data was collected by Edmund Basham 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 : edmund.basham@gmail.com
Surveys
This contains data relating to each sampling occasion, consisting of a vertical transect located on a tree. Tree code and Date (UK format throughout- DD/MM/YYYY) columns can be used to link surveys to individuals. Location can be determined by the longitude (decimal degrees) and latitude (decimal degrees), and elevation (meters above sea level) which are included. The start time of the survey (24hr throughout), total height (meters) of the tree, and the max height climbed (meters) to which the tree was surveyed are also included here.
Individuals
This contains data relating to the individuals captured and used in this study. Tree code 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 (meters) at which the individual was found. The raw trait values of Mass (g), Snout to Vent Length (mm), Mouth Width (mm), Toe Disc Width (mm), and Tibia Length (mm) are included here.
Traits
This contains the scaled and averaged trait data for all species, including ratio traits. NA results represent traits which were unable to be sampled in an individual.
Climate
This contains data relating to temperature taken at 30 minute intervals, as well as maximum, minimum, and mean daily temperature (Celsius), columns 1 - 5.
Secondly, represented by "rh" in columns 6 - 10, humidity (%) was taken at 30 minute intervals, as well as maximum, minimum, and mean daily results. Dewpoint (Celsius) is also included here in column 11.
Temperature were taken at separate trees (identified by the tree code column) from the soil, understory, and canopy, whereas humidity were only recorded at the understory and canopy. These are denoted by the "Strata" column. Data can be linked to the survey tab by tree code which contains their longitude and latitude coordinates. NA results represent summary columns which are only populated at the times where averages or maximum/minimum values are inputted. All values have a recorded time and date. Finally, the values of temperature and humidity range are included which are the maximum - the minimum values per day.
Methods
In southern Gabon, we surveyed a Dense Moist Forest (Verhegghen et al. 2012) located around Baposso Village, Ngounie Province, which borders the Monts Birougou Ramsar site (Lat 20°85′00″ N: Lon 12°13′50″; 650 – 800 m a.s.l, Figure 1). We focussed our sampling in older growth areas with mature trees, with primary canopy tree species including Mutombo, Wapaka, Posso, and Paduc. Temperature and humidity were measured at the site using climate loggers deployed in two arrays. One array comprised three temperature loggers (HOBO Temperature Pendant); the soil (10 cm below the surface), 2 m height in the understory, and 25 m height in the canopy. The second array utilised climate loggers (HOBO U23 Pro v2) in the understory and canopy which record humidity in addition to temperature. Loggers were protected from sunlight and weather by installation within a PVC T-Joint pipe which allowed airflow.
We surveyed for frogs during the wet season of 2022 (October – November). We conducted vertical, ground-to-canopy surveys for amphibians, with each survey centred on a single canopy tree. Tree selection was randomized; however, trees were required to be a minimum of 20 m apart and 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 74 trees at night for amphibians. 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 minute 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. Above-ground, we searched for arboreal amphibians in tree holes, moss, epiphytes and other microhabitat structures (Heyer et al. 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).
Encountered amphibians were photographed, weighed, and measured for snout-vent length (SVL), mouth width (hereafter: mouth), tibia length (hereafter: tibia), and toe disc width (3rd digit from inside thumb).