Arboreal microclimates across Philippines elevation gradient

The dataset provides microclimate time series for climate loggers in the canopy, the understory, and inside Asplenium bird's nest ferns along an elevation gradient spanning 900 m to 1900 m on Mt. Banahaw, the Philippines. Trait characteristics were additionally collected for the ferns in which microclimate were monitored.

Methods
The data were collected along an elevation gradient spanning 900 m to 1900 m a.s.l. on Mount Banahaw in southern Luzon, the Philippines. The gradient is characterized by dipterocarp and montane rainforest from 900 m to 1700 m and mossy and Pinus forest above 1700 m a.s.l.

Microclimate Data

We monitored temperature in the understory, canopy, and inside BNFs every 200 m in elevation using temperature data loggers (Maxim Hygrochron ibutton Model DS1923; http://www.maxim-ic.com/). We placed a pair of temperature loggers in four to five trees per elevation. In each tree, loggers were placed in the upper canopy, which varied across elevations and transects from an average of 11.75 m to 18.75 m, and directly below, suspended 1 m above the ground (hereafter ‘understory’). Paired canopy-understory loggers were separated by a minimum of 100 m to reduce spatial autocorrelation.

Along two 50 m transects at each elevation from 900 m to 1700 m, we quantified the abundance and the vertical distribution of BNFs by counting all BNFs that were visible from the transect and recording their height above ground using a laser distance meter (Leica Geosystems, Leica Disto D2; http://www.leica-geosystems.ca). We then calculated relative height of each BNF by dividing the height above ground by the average canopy height of the given elevation and transect. Average canopy height was obtained by surveying a total of 59 canopy trees for heights (14 trees at 900 m, five at 1100 m, 13 at 1300 m, five at 1500 m, 11 at 1700 m, five at 1900 m and six at 2100 m elevation).

We randomly selected a subset of 50 BNFs along one of the surveyed transects at each elevation for which we monitored microclimates. Data loggers were placed under detritus at the center of each fern. For these BNFs, we collected additional data on their habitat and morphological characteristics, including canopy cover (directly above fern), aspect, average length of the five longest fronds, fern size, and number of leaves. Fern size was measured as the width multiplied by the height of the humus-root ball. Data loggers recorded temperature at 15–20-minute intervals from May through September 2011 for canopy and understory microhabitats and June through August 2011 for BNF microhabitats. Habitat and morphological measurements and microclimate data were obtained for 50 BNFs. Due to technical malfunctions of data loggers, elevations were not represented equally (900 m: n = 8; 1100 m: n = 16; 1300 m: n = 15; 1500 m: n = 10; 1700 m: n = 1).

Precipitation data

Precipitation data was collected at 1100 m a.s.l.