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

樟子松是加拿大西部最重要的经济树种之一，其采伐量仅次于艾伯塔省的云杉，也是该省的主要树种。与此同时，松树目前正受到气候变化的严重压力，气候变化为山松甲虫的大规模侵扰和随后数千公顷的树木过早死亡提供了便利。艾伯塔省有五个针对樟子松的地区性树木改良计划，旨在为当地适应的、生长更快的樟子松幼苗提供收获后重新造林的机会。然而，与这些树木改良计划相关的一些樟子松种子园，未能达到种子产量目标高达80%。从这些项目中确保有足够的种子用于重新造林是一个主要问题。新发育的雌性球果的丧失(称为球果败育)已被认为是造成种子产量低的主要原因。初步研究表明，小球果的丢失发生在两年繁殖周期的早期，似乎受到遗传和种子园所在地点条件的影响。此外，嫁接树似乎表现出比种子起源的树更高的圆锥体败育率。然而，这次流产的根本原因尚不清楚。我们建议使用一种组合的方法，包括遥感、对冠层高度和根区内的环境条件的现场监测，以及生理测量来确定所观察到的球果败育的机制。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.