Treesearch

The five-needle pines have been an important part of the landscape of North America, but they have been severely affected by the introduction of white pine blister rust (causal agent: Cronartium ribicola). However, most of these species have one or more types of some inherent resistance to this exotic disease, such as major gene resistance (complete resistance), and some forms of partial resistance. Longestablished provenance trials in western white pine (WWP, Pinus monticola), established with unselected populations, allow us to investigate and compare genetic variation in our native...

Genetic variation in needle traits (number of rows of stomata, areal density of stomata, and density of stomata in a row, as well as needle length and needle width), seedling height growth, and early measures of blister rust (causal agent: Cronartium ribicola) resistance were examined among 22 openpollinated families of whitebark pine (Pinus albicaulis) from Crater Lake National Park (CLNP) in Oregon. Needle traits were examined for both the adaxial and abaxial sides. Needle traits were also assessed for 19 of 22 parent trees from CLNP. The adaxial side of the needle on average had more...

Provenance tests of 49 populations of whitebark pine (Pinus albicaulis) revealed moderate genetic differentiation for growth potential (growth under conditions approaching physiological optimum). Moderate genetic differentiation was also detected for survival after more than 10 years under warm-dry climate in the field but not for unconditional expected height, which was considered the best available predictor of fitness. Height was considered unconditional because survival over multiple years was explicitly included in the analysis. Genetic divergence for growth potential and survival was...

Southwestern white pine (Pinus strobiformis, syn. Pinus flexilis var. reflexa) is a high elevation five-needle pine. Pinus strobiformis occurs in mixed species stands across a range of elevations and forest types in western Texas, southwestern Colorado, and throughout New Mexico and Arizona (USA), and continues along the mountains south to central Mexico (Alexander et al. 1984; Looney and Waring 2013; Moreno-Letelier and Piñero 2011; Steinhoff and Andresen 1971) (fig. 1). This species, like all species of North American five-needle pines, is susceptible to infection and mortality from the...

Needle dimensions and stomate densities were measured for 300 seedlings representing a stratified sampling of 30 families of whitebark pine (Pinus albicaulis) from California, Oregon, Washington, Idaho, and Montana (USA), and British Columbia (Canada). The seedlings were selected from a larger common garden trial examining white pine blister rust (WPBR) resistance of 225 families from populations representing much of the geographic range of whitebark pine. The objective was to examine variation in needle characteristics, including needle width, number of stomata, and stomate density, and...

Direct seeding is an emerging technique that could significantly reduce the labor and costs associated with whitebark pine (Pinus albicaulis) restoration, and may be compatible with wilderness values. Because other restoration methods-including outplanting of seedlings-are largely incompatible with maintaining wilderness as "untrammeled and natural," the adoption of direct seeding may open an additional 48 percent of whitebark pine habitat to restoration efforts in the future.

Much of the information available on successional modeling for whitebark pine (Pinus albicaulis) communities is based on research conducted in an ecosystem influenced by maritime conditions (Pacific Northwest). The Greater Yellowstone ecosystem (GYE; Wyoming, Montana, and Idaho, USA) is subjected to more continental climatic conditions and as a result, the dynamics of whitebark pine populations in the GYE may in fact be very different from those of maritime populations. Recent survey work in the GYE shows establishment is common with variable recruitment of young trees in the understory of...

In some Rocky Mountain treeline ecotones, whitebark pine (Pinus albicaulis) serves as a tree island initiator more frequently than Engelmann spruce (Picea engelmannii) or subalpine fir (Abies lasiocarpa). Tree island initiation begins with a solitary krummholz tree, which provides sufficient leeward protection so that another tree may become established, resulting in a tree island. More trees may establish on the lee side over time. Whitebark pine mortality from white pine blister rust (pathogen: Cronartium ribicola) reduces opportunities for such facilitation. Will declines in whitebark...

During the naturalization process of white pine blister rust (WPBR, caused by Cronartium ribicola), susceptible pine genotypes will be selected against, along with any traits that are associated with those genotypes, potentially causing a shift in the suite of traits in the post-selection population compared to the native population. Consequently, identifying associated traits with WPBR resistance is critical for effective restoration planning, especially in a changing climate. We sought to determine whether complete resistance to WPBR in limber pine (Pinus flexilis) is associated with...

North America is a secondary center of diversification of the genus Pinus. Most of these speciation events are fairly recent, producing a pattern of widespread shared polymorphism and fuzzy species boundaries. Among five-needle pines, the relationships among Pinus flexilis, Pinus strobiformis, and Pinus ayacahuite have been particularly difficult to determine. To understand the speciation process and the phylogenetic relationships in this species complex, we evaluated genetic and ecological differentiation using multilocus sequence data and ecological niche model comparisons. Our results...