Dataset: Drought response strategies of vascular epiphytes in isolated pasture trees in a Costa Rican tropical montane landscape

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Datasets used in analyses for “Drought response strategies of vascular epiphytes in isolated pasture trees in a Costa Rican tropical montane landscape”. There are 4 combined sap flow/microclimate hourly datasets, 2 microclimate daily datasets, and datasets containing PV curve results, water potential, and leaf traits.

Sap flow references: (Burgess et al., 2001; Clearwater et al., 2009)
PV curve references: (Williams et al., 2017)
Leaf trait references: (Gotsch et al., 2022)

Common variables that appear in multiple datasets:
· Site (Upper = Ortega, Middle = Guindon, Lower = Zelmi)
· Species: 4 letter species code
· Ind: Non-unique plant identifier, must be combined with Site and Species for a unique key.
· Timestamp: Hourly as y-m-d h:m:s or daily as y-m-d
· Season: Dry or Wet
· Succulent: Sample comes from leaf succulent species, yes or no
· Type: Growth form of sampled individual (Woody single stem, woody multi stem, or herbaceous)

Sap velocity and microclimate datasets explained
· Sap_L4: The complete dataset after cleaning, baselining, and averaging to hourly intervals
· Sap_L4a: L4 averaged to the level of species within site
· Sap_L5: L4 filtered to the specific wet/dry weeks of interest
· Sap_L5a: L5 averaged to the level of species within site

Sap velocity and microclimate variables:
· EpiID: Unique epiphyte identifier consisting of Site letter, tree identifier, and number from 1-16.
· Sap.vel: Sap velocity (cm/hr)
· LWSup: Leaf wetness (g/m2)
· Solar: Solar radiation (W/m2)
· VPD: Vapor pressure deficit (Kpa)
· VWC.rel: Relative volumetric water content (Proportion)
· Precipitation: Water input to pluviometers (mm)

PV curve variables:
· TLP: Turgor loss point (MPa)
· totE: Bulk modulus of elasticity (MPa)
· CTarea: Hydraulic capacitance before TLP, normalized by fresh area (g m-2 MPa-1)

Water potential variables:
· Month (Feb, Mar, or Apr)
· Midday: Water potential taken at midday (MPa)
· Predawn: Water potential taken at predawn (MPa)
· Difference: Difference between midday and predawn measurements (MPa)
· TLP_mean: Mean turgor loss point of the species within site, calculated from PV curve data (MPa)
· Buffer: Difference between the Midday value and the TLP_mean (MPa)

Leaf traits:
· gmin: Minimum stomatal conductance (mmol m-2 s-1)
· LDMC: Leaf dry matter content (g g-1)
· SLA: Specific leaf area (cm2 g-1)
· Tough: Leaf toughness (g mm-2)
· SD: Stomatal density (# mm-2)
· LT: Leaf thickness (mm)
· LWC: Leaf water content (%)
· HT: Hydrenchymal thickness (mm)

References

Burgess SSO, Adams MA, Turner NC, Beverly CR, Ong CK, Khan AAH, Bleby TM. 2001. An improved heat pulse method to measure low and reverse rates of sap flow in woody plants (Tree Physiology 21 (589-598)). Tree Physiology 21: 1157.
Clearwater MJ, Luo Z, Mazzeo M, Dichio B. 2009. An external heat pulse method for measurement of sap flow through fruit pedicels, leaf petioles and other small-diameter stems. Plant, Cell and Environment 32: 1652–1663.
Gotsch SG, Williams CB, Bicaba R, Cruz-de Hoyos R, Darby A, Davidson K, Dix M, Duarte V, Glunk A, Green L, et al. 2022. Trade‑offs between succulent and non‑succulent epiphytes underlie variation in drought tolerance and avoidance. Oecologia.
Williams CB, Reese Næsborg R, Dawson TE. 2017. Coping with gravity: The foliar water relations of giant sequoia. Tree Physiology 37: 1312–1326.