Patterns and causes of temporal variation in tree seed production

树木的群集行为（定义为空间同步和时间偶发的种子作物生产）在生态学中具有极其重要的意义（例如，鹿和啮齿动物的戏剧性营养效应；食食性鸟类种群的爆发；风病物种的花粉通量等）。这在林业中也很重要——植被事件的不可预测性倾向于种植这种更昂贵但更可靠的再生选择。到目前为止，人们唯一能达成共识的说法是，丰年是一个地区存在的，年际花粉和胚珠的产生密切相关，一个地区内的大多数物种彼此不同步，天气无疑起着主要作用（为芽分化提供资源和/或线索）。提出的研究有许多目标，包括对纬度、海拔、经度和生活史特征（如空中种子库）的依赖的全球检查，以及一些松树物种的强制性鸟类传播。我将把我正在进行的数据集从6年扩展到11年，测量从科罗拉多州到北冰洋（Inuvik）以及从阿拉斯加内陆到纽芬兰的68个林分中云杉（Picea glauca）和非常接近的恩格尔曼云杉（P. engelmannii）的每基面积的卵细胞球果；然后我会用这些数据来测试基于资源的，基于线索的，或者资源和线索的组合的繁殖模型。此外，我将在阿尔伯塔省西部、马尼托巴省中部和魁北克省西北部的年轻白云杉林中进行一系列实验，通过在正常年份诱导水分胁迫，在非常干燥的年份进行灌溉，在杆年去除未成熟的雌性球果，以及在杆年安装人工球果簇来模仿真实球果的阴影，来比较资源和天气因素在控制年度繁殖产量方面的影响。最后，我将在四个空间上独立的北方森林区域将每基面积的球果和燃烧面积联系起来，以确定大火年之后是否通常会有肥大作物。

Masting behavior (defined as the spatially synchronous and temporally episodic production of seed crops) in tree species is of tremendous importance in ecology (e.g. dramatic trophic effects for deer and rodents; eruptions of granivorous bird populations; pollen flux in anemophilous species; etc). It is also quite important in forestry-the unpredictable nature of masting events has favored the more expensive but more reliable regeneration option of planting. As of now the only consensual statements one might make are that a mast year is of regional extant with inter-annual pollen and ovule production closely linked, most species within a region are not synchronized with one another, and weather undoubtedly plays a major role (generating resources and/or cues for bud differentiation). The proposed study has a number of objectives including a global examination of the dependence on masting on latitude, altitude, longitude, and life history traits such as aerial seedbanks and obligate bird dispersal of some Pine species. I will extend my on-going data set from 6 to 11 years, measuring ovulate cones per basal area of Picea glauca (white spruce) and the very close-related P. engelmannii (Engelmann spruce) in the same 68 stands from Colorado to the Arctic Ocean (Inuvik), and from interior Alaska to Newfoundland; and then I will use these data to test models of reproduction that are resource-based, cue-based, or a combination of resource and cue. Further, I will compare the effect of resources vs weather cues in governing annual reproductive output in a series of experiments in young white spruce stands in western Alberta, central Manitoba, and northwest Quebec by inducing water stress during normal years, irrigation during very dry years, removal of immature female cones during mast years, and installation of artificial clusters of cones to imitate the shading of real cones during mast years. Finally, I will relate cones per basal area and area burned in four spatially independent regions of the boreal forest to ascertain if big fire years are typically followed by mast crops.