Fire effects on tree physiology, growth, and drought vulnerability: Non-structural carbohydrate, hydraulic function, water potential, and tree growth data
Data files
May 06, 2025 version files 6.13 MB
-
fire_phys_data.zip
6.12 MB
-
README.md
10 KB
Abstract
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.
Dataset DOI: 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