DOI: 10.5061/dryad.63xsj3vfp
title: Setting the benchmark: Patterns of forest structure after wildfire in temperate, montane forests across a multi-century chronosequence

description: Many forest types are shaped by wildfire, which can reset ecological
 succession and modify species trajectories. Novel fire regimes are
 increasing globally, posing a major threat to forests. Understanding the
 successional dynamics of forests after wildfire is critical to develop
 evidence-based ‘benchmarks’ of forest structure to inform appropriate
 ecological management and restoration. However, this understanding is
 limited in intact forests over long periods, including those where old
 growth forest is sometimes used as a reference state. Several large,
 high-severity wildfires burned significant areas of the Mountain Ash
 (Eucalyptus regnans) forests in south-eastern Australia ≤1900, and in
 1926/1939 and 2009. Here, we take advantage of this fire history to
 implement a natural experiment to better understand the patterns and
 environmental drivers of variation in forest structure at 84 sites across
 a multi-century chronosequence. We explored inter-specific differences
 across major plant lifeforms in relation to stem size and density, and
 their relative interactions over time. Our findings indicate that: 1.
 Early-successional forests ≤10 years after wildfire in 2009 are
 characterised by a high, but variable, density of homogeneous-sized stems
 (≥7000 stems ha-1). In contrast, old-growth stands (≤1900 stand age) were
 characterised by the lowest number of stems, that were the least variable
 in density, but had the greatest variability in stem size, relative to
 other stand ages. 2. Environmental factors including slope and elevation
 influenced patterns of stem density, with the direction of the influence
 varying across lifeforms. 3. Interspecific relationships between
 individual plant lifeforms varied across the chronosequence, and were more
 negative in early-succession (2009 stand age), relative to
 late-succession. Synthesis: Our findings demonstrate that rates of
 self-thinning in forests following wildfire (that occur within historical
 fire-regimes), may result in a ~50-60% decline in stem count in the
 several decades between early-successional forests and mature (1926/1939
 stand age) forests, and then again between mature and old-growth forests.
 Self-thinning is a critical forest function, and represents one pathway
 through which structurally complex old-growth forests develop, providing
 significant ecological values. These empirical insights provide a
 benchmark to guide evidence-based restoration of montane forests in the
 face of predicted novel fire regimes.
description: # Setting the benchmark: Patterns of forest structure after wildfire in
 temperate, montane forests across a multi-century chronosequence Dataset
 DOI: [10.5061/dryad.63xsj3vfp](https://doi.org/10.5061/dryad.63xsj3vfp) ##
 Description of the data and file structure Data underpinning: **\ \
 Setting the benchmark: Patterns of forest structure after wildfire in
 temperate, montane forests across a multi-century chronosequence** Elle
 Bowd~1~, David Lindenmayer~1~ ~1~Fenner School of Environment and Society,
 The Australian National University, Canberra, ACT, 2601 ### Files and
 variables #### File: Stem_density_Oct25_Dryad.RData.xlsx 1. Sheet name:
 Stemsize_count | Sheet name: Stemsize\_count | 
 
 | | :-------------------------- | :---------------------------------- | |
 **Variables** | **Description** | | SiteCode | Site name | | Standage |
 Stand age (&lt;1900, 1926/1939,2009) | | Sum\_Stems | Count of stems | |
 Stem\_size | Size of stems (categorical measure) | 
 
 2. Sheet name: Stemcount_lifeform | Sheet name: Stemcount\_lifeform | 
 
 | | :------------------------------ |
 :------------------------------------------ | | **Variables** |
 **Description** | | SiteCode | Site name | | Standage | Stand age
 (&lt;1900, 1926/1939,2009) | | Acacia | Count of Acacia stems pooled
 across sizes | | Eucalypt | Count of Eucalypt stems pooled across sizes |
 | Shrub | Count of Shrub stems pooled across sizes | | Tree | Count of
 Tree stems pooled across sizes | | DEM\_m | Elevation in m | | Slope\_deg
 | Slope | | TWI\_ind | Topographical wetness index | | N\_aspect |
 North/Non-north aspect | 
 
 3. **Sheet Name: Stemcount_lifeform_stemsiz**e | Sheet
 Name: Stemcount\_lifeform\_stemsize | 
 
 | | :---------------------------------------- |
 :----------------------------------------- | | Variables | Description | |
 SiteCode | Site name | | Standage | Stand age (&lt;1900, 1926/1939, 2009)
 | | Lifeform | Lifeform (Acacia, Eucalypt, Tree or Shrub) | | DBH\_cm |
 Diameter at breast height (DBH) in cm | | Sum\_Stems | Count of stems |