Doctoral Dissertation Research: Mountain Pine Beetle and Fire Influences on the Regeneration of Lodgepole Pine in Northern Colorado

博士论文研究：山松甲虫和火灾对科罗拉多州北部黑松再生的影响

• 批准号: 1030845
• 负责人: Thomas Veblen
• 金额: $ 1.2万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1030845&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Mountain; Pine

Since the late 1990s severe mountain pine beetle outbreak (MPB; Dendroctonus ponderosae) and wildland fires have disturbed large expanses of northern Colorado's subalpine forests. The primary MPB host in the region, lodgepole pine (Pinus contorta var. latifolia), is considered a classic fire-adapted species due to its serotinous cone habit (cones which open in response to heat) and ability to establish rapidly following stand replacing fires. However, there is a substantial knowledge gap in how serotinous cones and lodgepole seedling recruitment respond to non-fire related disturbances (MPB epidemics), and how this response may further influence tree regeneration following future fires. Doctoral student Teresa Chapman, under the supervision of Professor Thomas Veblen in the Department of Geography at the University of Colorado Boulder examines how conditioning factors (e.g. site conditions, stand structure, seed availability and climate variability) determine the response of lodgepole pine regeneration to recent disturbance by MPB and fire, and how the current patterns of lodgepole pine regeneration following MPB outbreak may affect forest ecosystem responses to future fire. These questions are answered through a series of four objectives at multiple scales: 1) to compare lodgepole pine regeneration at sites either affected by severe fire in 2002 or by the MPB epidemic since 1996, 2) to investigate through field experimentation the reaction of serotinous cones and lodgepole pine germination to variable litter depth and canopy conditions, 3) to conduct broad scale sampling of post-MPB sites across northern Colorado to generate predictive maps of both regeneration patterns and lodgepole serotiny, and 4) to synthesize the empirically generated results through both the implementation of a stand scale predictive model of tree regeneration and a spatial overlay analysis of current MPB effects and their predicted consequences following future fires. The underlying hypothesis of the research is that current patterns of regeneration following the extensive MPB outbreak could lead to less fire resilient subalpine ecosystems. Understanding the ecological consequences of lodgepole pine tree mortality due to the current MPB outbreak affecting over one million hectares is a major concern among the general public and land managers in the Rocky Mountain region. Basic knowledge of the natural regeneration dynamics of lodgepole pine following severe, infrequent disturbance is essential for both short- and long-term predictions of subalpine ecosystem dynamics. The empirical data generated by this research will provide land managers with an initial basis for evaluating the potential for shifts in forest composition due to the interactions of the MPB outbreak with future fires. The immense extent and severity of both the MPB epidemic and 2002 fires provide a rare, natural experiment to study the regeneration response to such large, infrequent mortality events which may have important impacts on tree species distributions and regional-scale carbon budgets. This research will provide numerous undergraduates at the University of Colorado with field and laboratory research experience and with opportunities to develop senior honors theses.

自 20 世纪 90 年代末以来，严重的山松甲虫（MPB；Dendroctonus ponderosae）爆发和荒地火灾扰乱了科罗拉多州北部大片亚高山森林。该地区的主要 MPB 寄主黑松 (Pinus contorta var. latifolia) 被认为是典型的火适应树种，因为它具有浆果状的球果习性（球果响应热量而张开），并且能够在火灾发生后迅速建立林分。然而，对于浆果球果和黑松幼苗的补充如何应对非火灾相关的干扰（MPB流行病），以及这种反应如何进一步影响未来火灾后的树木再生，还存在很大的知识差距。 博士生 Teresa Chapman 在科罗拉多大学博尔德分校地理系 Thomas Veblen 教授的指导下，研究了调节因素（例如立地条件、林分结构、种子可用性和气候变化）如何决定黑松再生对近期 MPB 和火灾干扰的反应，以及 MPB 爆发后黑松再生的当前模式如何影响森林 生态系统对未来火灾的反应。这些问题通过多个尺度的一系列四个目标得到回答：1) 比较受 2002 年严重火灾影响或自 1996 年以来 MPB 流行影响的地点的黑松再生情况，2) 通过现场实验调查浆果和黑松发芽对不同的凋落物深度和树冠条件的反应，3) 对科罗拉多州北部 MPB 后地点进行大规模采样 生成再生模式和黑松血清的预测图，4) 通过实施树木再生的林分规模预测模型和对当前 MPB 效应及其未来火灾后的预测后果进行空间叠加分析，综合经验生成的结果。该研究的基本假设是，大规模 MPB 爆发后的当前再生模式可能会导致亚高山生态系统的防火能力较差。了解由于目前影响超过 100 万公顷的 MPB 爆发而造成的黑松树死亡所造成的生态后果，是落基山脉地区公众和土地管理者的主要关注点。 关于黑松在严重、不频繁的干扰后自然再生动态的基本知识对于亚高山生态系统动态的短期和长期预测至关重要。这项研究产生的经验数据将为土地管理者提供初步基础，以评估由于 MPB 爆发与未来火灾的相互作用而导致的森林构成变化的可能性。 MPB 流行病和 2002 年火灾的巨大范围和严重性提供了一个罕见的自然实验来研究对这种大规模、罕见的死亡事件的再生反应，这可能对树种分布和区域规模的碳预算产生重要影响。这项研究将为科罗拉多大学的众多本科生提供现场和实验室研究经验以及撰写高级荣誉论文的机会。