Reproductive maturity in boreal trees, Northwest Territories, Canada

In boreal North America, much of the landscape is covered by fire-adapted forests dominated by serotinous conifers. For these forests, reductions in fire return interval could limit reproductive success, owing to insufficient time for stands to reach reproductive maturity i.e., to initiate cone production. Improved understanding of the drivers of reproductive maturity can provide important information about the capacity of these forests to self-replace following fire. Here, we assessed the drivers of reproductive maturity in two dominant and widespread conifers, semi-serotinous black spruce and serotinous jack pine. Presence or absence of female cones were recorded in approximately 15,000 individuals within old and recently burned stands in two distinct ecozones of the Northwest Territories (NWT), Canada. Our results show that reproductive maturity was triggered by a minimum tree size threshold rather than an age threshold, with trees reaching reproductive maturity at smaller sizes wher...

在北美北方地区，大部分景观被火适应森林覆盖，这类森林以具延迟开裂特性的针叶树（serotinous conifers）为主导。对于这些森林而言，火回归间隔的缩短可能会限制其繁殖成功，原因在于林分缺乏足够时间达到生殖成熟——即启动球果生产。深入理解生殖成熟的驱动因素，可为揭示这些森林在火灾后的自我更新能力提供重要信息。本研究评估了两种优势且广布的针叶树（半延迟开裂的黑云杉（semi-serotinous black spruce）和具延迟开裂特性的杰克松（serotinous jack pine））生殖成熟的驱动因素。研究在加拿大西北地区（NWT）的两个不同生态区中，对老龄林分和近期火烧林分里的约15000株个体，记录了其雌球果的存在与否。结果表明，生殖成熟由最小树木大小阈值而非年龄阈值触发，且树木在...