Investigation of underlying causes for early conelet abortion in lodgepole pine seed orchards in Alberta

洛奇波勒松是加拿大西部最重要的经济树种之一，在阿尔伯塔省，洛奇波勒松是仅次于云杉的第二大采伐量，也是省树。与此同时，由于气候变化，山松甲虫的大规模侵扰和随后数千公顷树木的过早死亡，黑松目前正受到严重的压力。艾伯塔省有五个区域性的黑松改良方案，旨在提供适合当地的、生长更快的黑松幼苗，以便在收获后重新造林。然而，与这些树木改良计划相关的一些黑松种子园未能达到其种子产量目标高达80%。确保这些项目有足够的种子用于重新造林是一个主要问题。新发育的雌球果的丧失（称为小果流产）已被确定为这种低种子产量的主要原因。初步研究表明，在2年繁殖周期的早期，颖果的损失发生，似乎受到遗传和种子园所处的场地条件的影响。此外，嫁接树似乎比种子树表现出更高的圆锥花序流产率。然而，流产的根本原因尚不清楚。我们建议采用综合方法，包括遥感、冠层高度和根区环境条件的原位监测和生理测量，以确定观察到的松叶败育的机制。我们还打算提出建议，使果园管理者能够可靠地识别可能遭受高流产率的树木，从而实现种子产量目标。

Lodgepole pine is one of the most economically important tree species in Western Canada, contributing the second highest harvest volume after spruce in Alberta, where it is also the provincial tree. At the same time, lodgepole pine is currently under severe pressure from changes in climate which has facilitated the large-scale infestations of mountain pine beetles and subsequent early death of thousands of hectares of trees. Alberta has five regional tree improvement programs for lodgepole pine which are designed to provide locally adapted, faster growing lodgepole pine seedlings for reforestation after harvesting. However, some of the lodgepole pine seed orchards associated with these tree improvement programs, are failing to meet their seed yield targets by as much as 80%. Ensuring there is enough seed for reforestation from these programs is a major concern. Loss of newly developing female cones (called conelet abortion) has been identified as a major contributor to this low seed yield. Preliminary research has revealed that the loss of conelets occurs early in the 2-year reproductive cycle and appears to be influenced both by genetics and site conditions where the seed orchards are located. Moreover, grafted trees seem to show higher conelet abortion rates that trees originating from seeds. However, the underlying causes for this abortion remain unclear. We propose to use a combined approach, consisting of remote-sensing, in-situ monitoring of environmental conditions, both at canopy height and within the root-zone, and physiological measurements to determine the mechanisms underlying the observed conelet abortion. We also intend to develop recommendations that should allow orchard managers to reliably identify trees likely to suffer high abortion rates, allowing seed yield targets to be met.