DOI: 10.5061/dryad.qv9s4mws1
title: Fire effects on tree physiology, growth, and drought vulnerability: Non-structural carbohydrate, hydraulic function, water potential, and tree growth data

description: The mechanistic links between fire-caused injuries and post-fire tree
 function are poorly understood. Current hypotheses differentiate effects
 of fire on tree carbon balance and hydraulic function, yet critical
 uncertainties remain about the relative importance of each, how they
 interact, and whether these physiological impacts have consequences for
 post-fire growth and drought vulnerability. We utilized two prescribed
 burn sites and paired unburned control sites with Pseudotsuga menziesii
 and Pinus ponderosa to examine i) the relative evidence for fire-caused
 changes in hydraulic function (vulnerability to cavitation, hydraulic
 conductance) and carbon dynamics (non-structural carbohydrates; NSC), and
 how such impacts relate to fire injuries, ii) which impacts most likely
 lead to post-fire mortality, and iii) how these impacts affect post-fire
 radial growth and drought vulnerability (water potential, total water
 deficit). We found that fire-caused impacts to NSC were immediate,
 persistent, correlated with crown injury severity, and strongly related to
 post-fire mortality. In contrast, hydraulic impacts were delayed and not
 directly attributable to fire-caused injuries, although some burned trees
 did exhibit signs of increased hydraulic dysfunction and water stress
 prior to death, possibly due to an interaction with direct fire impacts on
 NSC. Fire-caused injuries also showed a strong negative relationship with
 post-fire growth, and tree-level total water deficit was generally higher
 in burned trees, particularly burned trees that experienced a post-fire
 drought treatment. This suggests a period of higher drought vulnerability
 and low growth post-fire, likely until recovery from fire injuries occurs.
 These findings offer a more nuanced understanding of fire’s effect on
 post-fire tree function and mortality and are important in the context of
 increased fire activity in forests globally.
description: # Fire effects on tree physiology, growth, and drought vulnerability:
 Non-structural carbohydrate, hydraulic function, water potential, and tree
 growth data Dataset DOI:
 [10.5061/dryad.qv9s4mws1](10.5061/dryad.qv9s4mws1) ## Description of the
 data and file structure These files include data associated with the
 manuscripts "Fire directly affects tree carbon balance and indirectly
 affects hydraulic function: consequences for post-fire mortality in two
 conifers" (Reed et al., in press), and "Fire-caused injuries may
 result in a period of reduced tree growth and elevated drought
 vulnerability after fire: A case study of two western U.S. conifers"
 (Reed et al., in prep). Data cover two prescribed burned sites (fall-burn,
 spring-burn) and paired unburned control sites in western Montana, USA and
 a total of 160 focal trees (80 ponderosa pine, 80 Douglas-fir). Data (tree
 attributes, non-structural carbohydrates, hydraulic function, water
 potential) were collected both pre-burn and at various timesteps
 post-burn. A drought experiment using rainfall exclusion shelters was
 conducted on half of the study trees, and we include soil moisture data
 taken during the drought treatment. We also include data on radial growth
 collected from tree cores on all study trees (basal area increment), and
 dendrometers on a subset of study trees (raw data included). ### Files and
 variables #### File: fire\_phys\_data.zip **Description:** Contains all
 data files (listed below) **tree_nsc_hydraulics_data.csv** - contains tree
 attribute, fire injury, neighborhood competition, non-structural
 carbohydrate, and hydraulic function (native hydraulic conductivity, P12,
 P50, P88) data SITE = Fall or spring burn (fall; spring) SITE_TREATMENT =
 Burn or control (unburned) site TREE_TAG = Tag number on tree
 TREE_TREATMENT = Drought or control tree; NA=not applicable as these trees
 were not sampled beyond T0 SPECIES = Tree species; PIPO=ponderosa pine
 (*Pinus ponderosa*), PSME=Douglas-fir (*Pseudotsuga menziesii*) TIMESTEP =
 Timestep at which the variable was measured (see sampling_dates.csv for
 detail on sampling dates) REPLACED = Y/N; Was this tree replaced with
 another for T1 sampling? Typically this occurred because the tree either
 died in the fire or did not see fire. Only applies to trees that were
 tagged pre-fire. The trees that served as replacements get NA value.
 STATUS = Tree status at the time of sampling; L=live, D=dead END_OUTCOME =
 Tree status at the end of the study DBH = Diameter (cm) at 1.3 m;
 collected pre-fire (T0) and at final sampling timestep; NA=data not
 re-collected because tree was dead HEIGHT = Height (m); collected pre-fire
 (T0) and at final sampling timestep; NA=data not re-collected because tree
 was dead CROWN_RATIO = Live crown ratio (%); compacted; NA=data not
 collected at this timestep (if STATUS='L'), or not collected
 because tree was dead CROWN_FUEL_BASE_HT = Live crown fuel base height
 (m); NA=data not collected at this timestep (if STATUS='L'), or
 not collected because tree was dead BARK_THICKNESS = Bark thickness at DBH
 (cm); only collected pre-fire (T0); NA=data not included because tree was
 dead INSECTS = Noted presence of beetles/defoliators post-fire (not
 collected at all timesteps); SBW=spruce budworm, RTB=red turpentine
 beetle; NA=insect presence/absence not recorded at this timestep SLOPE =
 Slope (%) where tree is located; percent; NA=data not collected (if
 REPLACED='Y'), or not included because tree was dead
 LITTER_DEPTH = Depth of litter (cm) at dripline on north side of tree
 (unless otherwise noted); NA=data not collected at this timestep
 DUFF_DEPTH = Depth of duff (cm) at dripline on north side of tree (unless
 otherwise noted); NA=data not collected at this timestep SCORCH_HT =
 Height (m) of scorch on focal tree; collected approximately 3 weeks
 post-fire (T1); NA=not collected (if SITE_TREATMENT='control'),
 or not included because tree was dead CROWN_SCORCH = Percent volume crown
 scorched (%); visually estimated; includes needles consumed; collected
 approximately 3 weeks post-fire (T1); NA=not collected (unburned site)
 CROWN_KILL = Percent (%) of buds killed in fire; visually estimated;
 collected approximately 3 weeks post-fire (T1); NA=not collected (unburned
 site) CKR = Cambium kill rating (0-4); number of quadrants around the base
 of a tree with dead cambium; collected in summer 2024; NA=not collected
 (unburned site) FIELD_COMMENTS = Comments from collection of tree data in
 the field at each timestep; NA=no comments included COMPETITION_INDEX =
 Hegyi index (Hegyi 1974); calculated within 5 m of focal tree; NA=not
 collected for these trees because they were replaced XYLEM_TOTAL_SUGARS =
 Percent (%) total sugars in the main stem xylem; NA=not collected due to
 sampling error XYLEM_STARCH = Percent (%) starch in the main stem xylem;
 NA=not collected due to sampling error PHLOEM_TOTAL_SUGARS = Percent (%)
 total sugars in the main stem phloem; NA=not collected due to sampling
 error PHLOEM_STARCH = Percent (%) starch in the main stem phloem; NA=not
 collected due to sampling error ROOTS_TOTAL_SUGARS = Percent (%) total
 sugars in coarse roots; NA=not collected at this timestep ROOTS_STARCH =
 Percent (%) starch in coarse roots; NA=not collected at this timestep
 NSC_COMMENTS = Comments from NSC collection or analyses; NA=no comments
 NATIVE_K = Specific hydraulic conductivity (kg s-1 m-1 MPa-1); branches
 sampled from top 1/2 of crown, terminal branches unless otherwise noted
 (green branches, live bud); NA=not collected due to sampling error
 NATIVE_K_SCORCH = Specific hydraulic conductivity (kg s-1 m-1 MPa-1) from
 scorched branches (ponderosa pine only) with live buds; NA=not collected
 at this timestep HYDRAULICS_COMMENTS = Comments from hydraulics sample
 collection or analyses; NA=no comments P12 = (MPa) from same branches as
 native_k measurements; green branches with live buds; NA=not collected at
 this timestep P12_SCORCH = p12 (MPa) from same branches as native_k_scorch
 measurements; scorched branches with live buds; NA=not collected at this
 timestep P50 = p50 (MPa) from same branches as native_k measurements;
 green branches with live buds; NA=not collected at this timestep
 P50_SCORCH = p50 (MPa) from same branches as native_k_scorch measurements;
 scorched branches with live buds; NA=not collected at this timestep P88 =
 p88 (MPa) from same branches as native_k measurements; green branches with
 live buds; NA=not collected at this timestep P88_SCORCH = p88 (MPa) from
 same branches as native_k_scorch measurements; scorched branches with live
 buds; NA=not collected at this timestep **water_potential_data.csv** -
 contains water potential (mid-day, pre-dawn) data collected on the same
 trees as in tree_nsc_hydraulics_data.csv SITE = Fall or spring burn (fall;
 spring) SITE_TREATMENT = Burn or control (unburned) site TREE_TAG = Tag
 number on tree TREE_TREATMENT = Drought or control tree; NA=tree was
 replaced before treatment TIMESTEP = Timestep at which the variable was
 measured (see sampling_dates.csv for detail on sampling dates)
 PREDAWN_WATER_POTENTIAL = Pre-dawn water potential (MPa); NA=not collected
 due to sampling error MIDDAY_WATER_POTENTIAL = Mid-day water potential
 (MPa); NA=not collected due to sampling error WATER_POTENTIAL_COMMENTS =
 Notes associated with water potential measurements; NA=no comments
 **soil_moisture_data.csv** - contains volumetric soil water content data
 associated with drought experiment; data collected on same trees
 as in tree_nsc_hydraulics_data.csv YEAR = Year of sampling; sampling
 occurred in either July of 2023 or June of 2024 SITE = Fall or spring burn
 (fall; spring) SITE_TREATMENT = Burn or control (unburned) site TREE_TAG =
 Tag number on tree TREE_TREATMENT = Drought or control tree
 SOIL_MOISTURE_VWC = Volumetric soil water content (%) at 12 cm depth
 **radial_growth_bai_data.csv** -  contains radial growth (basal area
 increment; BAI) data; data collected on same trees
 as in tree_nsc_hydraulics_data.csv SITE = Fall or spring burn (fall;
 spring) SITE_TREATMENT = Burn or control (unburned) site TREE_TAG = Tag
 number on tree YEAR = Growth year BAI = Basal area increment (cm^2); NA=no
 data because tree had died **dendrometer_data_fall_sites.csv** - contains
 raw data collected from dendrometers on a subset of the fall-burned trees
 listed in tree_nsc_hydraulics_data.csv TREE_TAG = Tag number on tree SITE
 =  Fall or spring burn (fall; spring) SITE_TREATMENT = Burn or control
 (unburned) site TREE_TREATMENT = Drought or control tree DATE_TIME = Date
 and time of recorded measurement DATA_STARTING_0 = Dendrometer data (µm),
 adjusted to start at 0 when first installed; blank=no data collected due
 to dendrometer error COMMENTS = Comments associated with dendrometers
 **dendrometer_data_spring_sites.csv** - contains raw data collected from
 dendrometers on a subset of the spring-burned trees listed
 in tree_nsc_hydraulics_data.csv TREE_TAG = Tag number on tree SITE =  Fall
 or spring burn (fall; spring) SITE_TREATMENT = Burn or control (unburned)
 site TREE_TREATMENT = Drought or control tree DATE_TIME = Date and time of
 recorded measurement DATA_STARTING_0 = Dendrometer data (µm), adjusted to
 start at 0 when first installed; blank=no data collected due to
 dendrometer error COMMENTS = Comments associated with dendrometers
 **sampling_dates.csv** - contains data on the sampling dates for all
 physiological measurements and tree attribute data TIMESTEP = Timestep
 label at which the variable was measured SITE = Fall or spring burn (fall;
 spring) SITE_TREATMENT = Burn or control (unburned) site MEASUREMENT =
 Description of measurement DATE = Sampling date
 **variable_descriptions.csv** - variable descriptions for all data files
 Filename = Name of .csv file Variable = Variable name used in data file
 Units = Units of variable Precision = Precision of variable Description =
 Description of variable