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

黑松是加拿大西部最重要的经济树种之一，在阿尔伯塔省的收获量仅次于云杉，也是该省的省树。与此同时，黑松目前正受到气候变化的严重压力，气候变化促进了山松甲虫的大规模侵扰，随后数千公顷的树木过早死亡。阿尔伯塔有五个区域性的黑松树木改良计划，旨在提供适应当地情况的、生长更快的黑松幼苗，以便在收获后重新造林。然而，一些与这些树木改良计划相关的黑松种子园未能达到其种子产量目标的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。新发育的雌球花的损失（称为小球花败育）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年生殖周期的早期就发生了连接性的丧失，这似乎受到遗传和种子园所在地的立地条件的影响。此外，嫁接树似乎表现出更高的小孢子败育率，种子起源的树木。然而，这种流产的根本原因仍不清楚。我们建议使用一种组合的方法，包括遥感，原位监测环境条件，在树冠高度和根区，和生理测量，以确定所观察到的小孢子败育的机制。我们还打算制定建议，使果园管理人员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.