Data from: Distinct diversity Trajectories of Boreal wood-inhabiting fungi following fire vs. clear-cutting

Here, we describe the data and methods supporting a study on how
disturbances such as forest fires and clear-cutting influence
wood-inhabiting fungal diversity trajectories in boreal Scots pine (Pinus
sylvestris) forests in Northern Sweden. The research contrasts two
chronosequences, one under rotational management (clear-cutting, soil
scarification, and thinning) and one unmanaged and fire-origin. Two
contrasting disturbance regimes – wildfire and clear-cutting – are common
in boreal forests, and create fundamentally different conditions for
succession of wood-inhabiting fungi. We investigated (i) how species
richness and community composition change after these two disturbances,
and (ii) which stand-level characteristics drive diversity trajectories.
In two chronosequences – managed clear-cut (1–109yr since clear-cut; n=18)
and unmanaged fire (4–375yr since fire; n=18) – we combined fruiting-body
surveys with DNA metabarcoding to quantify species richness of
wood-inhabiting fungi, including total number of species, Agaricomycete
and red-listed species. To identify drivers, we measured deadwood
attributes and forest structural complexity using terrestrial laser
scanning. Species richness, including red-listed species, was highest in
unmanaged fire stands. Unmanaged fire stands had ~55 more total species
than managed clear-cut stands at comparable time since disturbance
(≤109yr), and ~156 more species in stands >109yr. Communities
differed markedly between chronosequence types. Managed clear-cut stands
harbored a subset of species found in unmanaged fire stands, and nearly
all red-listed and indicator species were exclusive to unmanaged fire
stands. Total and Agaricomycete species richness increased with time in
both chronosequences without saturating. Red-listed species richness
remained low and did not increase with time in managed clear-cut stands,
but was higher and increased with time in unmanaged fire stands.
Conditional random forest models identified spruce deadwood percentage,
deadwood volume, and forest structural complexity as dominant diversity
drivers, with deadwood quality replacing forest structure as the best
predictor for red-listed species. Species richness rose steadily with
deadwood volume, leveling at ~50m³ha⁻¹ for total species and
>100m³ha⁻¹ for red-listed species. Synthesis: Clear-cutting altered
fungal recovery trajectories differently from fire. While fires leave
standing and fallen dead trees that host fungal communities for centuries,
clear-cutting removes these legacies and simplifies forest structure,
resulting in a lack of recovery of red-listed species. These contrasting
disturbance pathways shape boreal fungal communities through their effects
on deadwood and structural continuity. Retaining high deadwood volumes and
structural complexity can help maintain fungal diversity in managed
forests, however maintaining old-growth stands is essential for conserving
highly diverse communities and red-listed species.

本研究聚焦瑞典北部北方针叶林带的欧洲赤松（Pinus sylvestris）林分，阐述了用以解析林火与皆伐等干扰如何影响木质栖生真菌多样性演替轨迹的数据集与研究方法。
本研究对比两类时间序列样地：一类为轮伐经营林（包含皆伐、土壤松耙整地与疏伐措施），另一类为天然火起源的未经营林分。
林火与皆伐作为两类截然不同的干扰类型，在北方针叶林带中广泛分布，二者为木质栖生真菌的群落演替塑造了本质迥异的生境条件。
本研究旨在解答两个核心科学问题：其一，两类干扰后物种丰富度与群落组成将发生何种变化；其二，哪些林分尺度的特征能够驱动真菌多样性的演替轨迹。
针对两类时间序列样地——皆伐经营林（皆伐后1~109年，样本量n=18）与火起源未经营林（火后4~375年，样本量n=18）——本研究结合子实体调查与DNA宏条形码（DNA metabarcoding）技术，对木质栖生真菌的物种丰富度进行定量分析，涵盖物种总数、伞菌纲（Agaricomycetes）物种与红色名录物种的丰富度。
为明确多样性驱动因子，本研究借助地面激光扫描技术测定了枯倒木特征与森林结构复杂度。
包括红色名录物种在内的总物种丰富度，在火起源未经营林分中达到最高水平。
在干扰后时长相当（≤109年）的林分中，火起源未经营林分的总物种数较皆伐经营林分多出约55种；而在干扰后时长＞109年的林分中，二者的物种数差距进一步扩大至约156种。
两类时间序列样地的真菌群落组成存在显著差异。
皆伐经营林分仅包含火起源未经营林分中部分物种，且几乎所有红色名录物种与指示物种均仅存在于火起源未经营林分中。
两类时间序列样地中，总物种丰富度与伞菌纲物种丰富度均随时间推移持续上升，未出现饱和趋势。
皆伐经营林分中的红色名录物种丰富度始终处于较低水平，且未随时间推移出现显著上升；而火起源未经营林分的红色名录物种丰富度则相对更高，且随时间持续增长。
条件随机森林（Conditional random forest）模型结果显示，云杉枯倒木占比、枯倒木蓄积量与森林结构复杂度是影响真菌多样性的核心驱动因子；其中，枯倒木质量可替代森林结构，成为预测红色名录物种丰富度的最优指标。
物种丰富度随枯倒木蓄积量的增加呈稳步上升趋势，总物种丰富度在枯倒木蓄积量达到约50m³ha⁻¹时趋于平稳，红色名录物种丰富度则在蓄积量超过100m³ha⁻¹时达到平稳。
研究总结：皆伐与林火对真菌群落恢复轨迹的影响存在本质差异。林火会保留存活与枯倒的枯立木与倒木，这些基质可为真菌群落提供长达数百年的栖息环境；而皆伐会清除这类生境遗留物，同时简化森林结构，导致红色名录物种无法完成群落恢复。
两类截然不同的干扰路径通过影响枯倒木资源与结构连续性，塑造了北方针叶林带的真菌群落组成。在经营林分中保留高蓄积量的枯倒木与结构复杂度，有助于维持真菌多样性；但要保护高度多样的真菌群落与红色名录物种，维持原始老龄林分则是必不可少的措施。