Data from: Seed moisture content as a primary trait regulating the lethal temperature thresholds of seeds.

1) Fire has shaped biological responses of plants and plant communities in
fire-prone systems and is linked to myriad ecological processes but also
frequently puts people and infrastructure at risk. Fuel or
hazard-reduction burning is a common practice aimed at reducing the risk
of high-severity fires, which ideally also incorporates consideration of
biodiversity values. Within fire-prone systems, seed banks are often
critical for plant species’ regeneration, and seeds are typically adapted
to survive the passage of fire and to regenerate in response to cues
associated with natural fire regimes. However, species-specific tolerances
to the heat from fire exist; likely influenced by a range of physical,
physiological, and morphological seed traits. Identification of these
tolerances and associated seed traits may inform fire and
species-management. 2) We determined the lethal temperatures for seeds in
relation to their moisture content, and other key traits that we
hypothesised may be associated with survival. Seeds from 14 native
species, and 4 species invasive to fire-prone Mediterranean climate
Banksia woodlands of southwestern Australia, were exposed to temperatures
between 50 °C and 180 °C for 3 mins, at three different moisture contents.
The temperature at which half the seeds were killed (T50) was estimated
using non-linear log-logistic modelling. Seed mass, seed shape, embryo
type, plant resprouting ability, seed storage syndrome, and
native/invasive status, were measured and modelled for their correlation
with T50. 3) Increased moisture content was a significant predictor of
elevated seed mortality. Seeds with low moisture content (those
pre-conditioned at 15 or 50% RH), were able to survive far hotter
temperatures (median increase of 38 °C and 31°C respectively), than those
with high moisture content (those pre-conditioned at 95% RH). Of other
traits considered, seeds with basal embryos showed significantly lower T50
than other embryo types. 4) Synthesis: Seeds with higher moisture contents
have lower lethal temperature thresholds, leading to higher seed mortality
during fire events when seeds (and soils) are moist. Thermal tolerance
varied among co-existing species within this fire-prone system. These data
suggest potential concern for the impacts of aseasonal burning practices
(i.e. cool/wet season burning), and highlight the importance of taking
seed moisture content into account when planning and implementing
prescribed burning.

1) 火灾塑造了易火系统中植物及植物群落的生物学响应，与无数生态过程相关联，但也频繁将人类及基础设施置于风险之中。燃料或减灾焚烧是降低高烈度火灾风险的常见措施，理想情况下还应兼顾生物多样性价值。在易火系统内，种子库通常对植物物种的再生至关重要，种子一般经演化适应以在火灾中存活，并响应自然火制度（fire regime）相关的信号进行再生。然而，物种间存在对火的耐热性差异，这可能受多种物理、生理及形态学种子性状的影响。识别这些耐热性及相关种子性状可为火灾管理及物种管理提供参考。
2) 我们测定了种子的致死温度及其与含水量的关系，以及我们假设可能与存活相关的其他关键性状。选取澳大利亚西南部易火地中海气候区班克木（Banksia）林地中的14种本地物种及4种入侵物种的种子，在三种不同含水量条件下暴露于50°C至180°C的温度中3分钟。使用非线性对数逻辑模型估算半数种子死亡时的温度（T50）。测量并建模分析了种子质量、种子形状、胚胎类型、植物萌芽能力、种子储存综合征及本地/入侵状态与T50的相关性。
3) 含水量增加是种子死亡率升高的显著预测因子。低含水量种子（预处理于15%或50%相对湿度）比高含水量种子（预处理于95%相对湿度）能耐受更高温度（中位数分别提高38°C和31°C）。在考虑的其他性状中，具有基生胚的种子T50显著低于其他胚胎类型。
4) 综合分析：含水量较高的种子致死温度阈值较低，导致火灾发生时（种子及土壤湿润）种子死亡率更高。该易火系统内共存物种的耐热性存在差异。这些数据表明，非季节性焚烧措施（如凉爽/湿润季节焚烧）的影响值得关注，并强调在规划和实施计划烧除时考虑种子含水量的重要性。