Treesearch

Large, high severity fires are becoming more prevalent in Sierra Nevada mixed-conifer forests, largely due to heavy fuel loading and forest densification caused by past and current management practices. In post-fire areas distant from seed trees, conifers are often planted to re-establish a forest and to prevent a potential type-conversion to shrub fields. Typical reforestation efforts promote conifer survival and growth by reducing competing shrub cover, yet the effects of these practices on plant species richness and composition are not well understood. We compared the effects of...

1. The Long-Term Ecological Research (LTER) program has not influenced my basic approach to science. 2. The LTER program has reinforced my approach to mentoring, and it has increased my opportunities to mentor students through the LTER-associated Research Experiences for Undergraduates Program. 3. LTER program has greatly enriched my collaborative network and expanded my research in directions that I would not have otherwise pursued; similarly, I have expanded the research and perspectives of my collaborators. 4. My involvement in the LTER program has changed my perspective in reviewing...

Extensive mortality of whitebark pine, beginning in the early to mid-2000s, occurred in the Greater Yellowstone Ecosystem (GYE) of the western USA, primarily from mountain pine beetle but also from other threats such as white pine blister rust. The climatic drivers of this recent mortality and the potential for future whitebark pine mortality from mountain pine beetle are not well understood, yet are important considerations in whether to list whitebark pine as a threatened or endangered species. We sought to increase the understanding of climate influences on mountain pine beetle outbreaks...

Establishing efficient functional genomic systems for creating and characterizing genetic variation in forest trees is challenging. Here we describe protocols for creating novel gene-dosage variation in Populus through gamma-irradiation of pollen, followed by genomic analysis to identify chromosomal regions that have been deleted or inserted in each F1 individual. Irradiated pollen is used in a controlled, interspecific cross to create F1 progeny that carry deletions and insertions of chromosomal regions. These insertions and deletions result in novel changes in gene dosage that in turn...

Landscape genetics has advanced the field of evolutionary ecology by providing a direct focus on relationships between landscape patterns and population processes, such as gene flow, selection, and genetic drift. This chapter discusses the current and emerging challenges and opportunities, which focus and facilitate future progress in the field. It presents ten conclusions drawn about the current state-of-the-art in landscape genetics. Landscape genomics is one way to fully grasp the various influences that landscape can have on neutral and adaptive genetic variation. A major challenge in...

Landscape genetic studies have focused on terrestrial animals more than any other taxonomic group. This chapter focuses on applications of landscape genetics for understanding connectivity of terrestrial animal populations. It starts with a general introduction covering unique characteristics and challenges of the terrestrial study system. This is followed by an overview of common research questions addressed in terrestrial animals using neutral markers in landscape genetics. These common research questions include detecting and defining barriers, identifying corridors, examining source-sin...

An understanding of soil thermal conductivity after a wildfire or controlled burn is important to land management and post-fire recovery efforts. Although soil thermal conductivity has been well studied for non-fire heated soils, comprehensive data that evaluate the long-term effect of extreme heating from a fire on the soil thermal conductivity are limited. The purpose of this study was to evaluate the long-term impact of fire on the effective thermal conductivity of soils by directly comparing fire-heated and no-fire control soils through a series of laboratory studies. The thermal...

Elements of the natural world, such as mountains, rivers, and forests, are often seen as sacred in many cultural traditions. Recent conservation movements have even begun to draw on spiritual and religious beliefs to promote issues of environmental sustainability. The straightforward assumption in these cases is that sacred beliefs (compared with secular ones) will hold greater sway in alerting people to various environmental perils. However, environmental risk perception is a complex process, and we find that, in some cases, viewing natural resources as sacred may lead to a diminished...

Pacific Northwest forest managers seek estimates of post-timber-harvest woody residue volumes and biomass that can be related to readily available site- and tree-level attributes. To better predict residue production, researchers investigated variability in residue ratios, growing-stock residue volume per mill-delivered volume, across Idaho, Montana, Oregon, and Washington. This project presented unique sample design challenges, and the authors adopted model-based sampling to calculate the growing-stock logging residue ratio for the four-state region and produced models that relate the...

The woody stems of trees perceive gravity to determine their orientation, and can produce reaction woods to reinforce or change their position. Together, graviperception and reaction woods play fundamental roles in tree architecture, posture control, and reorientation of stems displaced by wind or other environmental forces. Angiosperms and gymnosperms have evolved strikingly different types of reaction wood. Tension wood of angiosperms creates strong tensile force to pull stems upward, while compression wood of gymnosperms creates compressive force to push stems upward. In this review,...