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Sugar pine (Pinus lambertiana) is a major component of the mixed-conifer forests found in the Sierra Nevada Mountains of California, USA. In the past several decades, sugar pine mortality has increased due to an introduced pathogen, white pine blister rust (caused by Cronartium ribicola). This study described stand development patterns in the mixed-conifer forests and quantified stand and tree growth response to the loss of sugar pine. Stratification patterns tended to follow patterns of shade tolerance with the more shade tolerant species found in lower canopy positions. Growth response was analyzed following the initial entry of blister rust and after more recent sugar pine mortality. Following the initial wave of mortality induced by blister rust, overstory trees and most individual species increased overall basal area growth. Although most species also responded to recent sugar pine mortality (occurring within the past ten years) by increasing basal area growth, the increase was only significant for white fir. Mortality of sugar pine has favored other conifer species, leading to changes in species dominance and negative effects on understory growth of sugar pine; release of these trees could improve overstory recruitment of sugar pine. However, due to the increased growth of white fir, any management strategies aimed at restoring sugar pine must also consider white fir management.
We established long-term alpine monitoring in southwestern British Columbia (BC) by following the protocol outlined in the Global Observation Research Initiative in Alpine environments (GLORIA). Monitoring sites were located on the Mount Arrowsmith Massif on Vancouver Island (Arrowsmith Biosphere Reserve) and in close proximity to Whistler Mountain (Garibaldi Provincial Park) in the summer of 2006. The aim of the GLORIA project is to develop a long-term, world-wide database of standardized observations of alpine biodiversity, vegetation patterns and mountain-top temperature. In both the Arrowsmith and Whistler target regions, the most dominant species in terms of cover were woody plants and included mountain hemlock (Tsuga mertensiana), white mountain-heather (Cassiope mertensiana) and subalpine fir (Abies lasiocarpa) in order of cover percentage. Thirty-nine vascular plant species were common to both target regions, 36 species were inventoried only in the Arrowsmith region and 28 species were only recorded in the Whistler region. No conclusive trends in species numbers were evident from baseline data. With plans to monitor and resurvey at five-year intervals, the sites established in this project document current plant species composition, and allow for a long-term assessment of changes in biodiversity attributable primarily to change in climate.
We explored geographic patterns and synchrony of Oregon white oak (Quercus garryana) acorn production over 8 years from Vancouver Island, British Columbia to Medford, Oregon. We divided our data into geographic areas: Puget-Willamette Trough, Columbia Gorge-East Cascades (Eastside) xeric, Eastside mesic, Cascade Mountain foothills, Roseburg, and Medford to compare annual acorn production among areas. We observed high within-area synchrony, but synchrony across areas was only apparent in 2004 and 2006 (high production), and 2005 (low production). Correlogram analysis indicated significant acorn crop correlation throughout the Puget-Willamette Trough, but synchrony was higher over greater distances among stands than among trees. Relationships between acorn production and mean monthly temperature or precipitation were examined with correlation analyses for each month between floral initiation and acorn maturation over 8 years of observations. Acorn production in the Puget-Willamette Trough was negatively correlated with spring precipitation, possibly due to an effect on floral processes, and winter temperature, which might relate to bud chilling requirements. In Eastside uplands, June precipitation positively correlated with current acorn production, but negatively correlated with the following year's production suggesting a climatically mediated depression by one year's production on that in the following year. Eastside production negatively correlated with precipitation in March suggesting precipitation interferes with floral processes at that time. We developed predictive linear regression models for the two analysis areas with largest sample sizes. Oregon white oak masting is similar to that in other white oaks in terms of periodicity and the effects of spring weather, but is also influenced by other weather related factors following floral induction.
Water dynamics in decaying conifer logs of four species (Abies amabilis [Pacific silver fir], Pseudotsuga menziesii [Douglas-fir], Thuja plicata [western red cedar], and Tsuga heterophylla [western hemlock]) were studied in the Coast Range of Oregon. Measurements were made of throughfall, leachate, runoff, and absorption for logs during their 6th through 8th year of decay. During this period 47–70% of the throughfall landing on the logs evaporated, 18–35% flowed through the log and leached out, 3–29% ran off the surface, and absorption accounted for 3–11%.
Together absorption and evaporation intercepted 60% of the throughfall impacting the logs. Although the second year of the study had twice as much precipitation as the first, the partition of the fluxes was essentially identical. Direct measurement of the changes in log weight allowed calculation of water stores and the evaporative component; the latter proved to be the largest fraction of the water balance, with the majority of losses during the cool, wet, winter period.
Carcasses are potentially a valuable source of DNA for genetic studies of Pacific salmon (Oncorhynchus sp.). They can be collected at spawning grounds across a wide geographic area and include populations in streams in which it is logistically difficult or too intrusive to sample spawning fish. However, the quality and quantity of DNA from salmon carcasses is highly variable. Using a standardized set of microsatellite loci, we investigated the relationship of amplification success and genotyping errors to time since death and locus size in Chinook salmon (O. tshawytscha) carcasses. Amplification success declined rapidly from death, smaller loci had greater amplification success than larger loci, and genotyping errors were present in 5% of scored samples. Salmon carcasses can be a valuable source of genetic information; however, the level of effort needed to produce accurate and reliable data with microsatellite loci is considerable. Ideally, field collections should be frequent and focus on fresh carcasses. Data replication should also be incorporated into analyses to reduce amplification failures and genotyping errors. New techniques and markers should improve future cost-effectiveness when analyzing degraded tissue samples. However, we recommend that an evaluation of cost and time be performed at the onset of any population genetic study using salmon carcass tissues, regardless of the technique used.
Roadkill is the main cause of mortality for the endangered subspecies of American badger found in British Columbia (Taxidea taxus jeffersonii). Badgers sometimes use culverts to pass under roads, so more culverts might be associated with less roadkill risk. Risk may also be associated with the presence of Jersey barriers, which potentially trap badgers on roadways. We compared 39 1-km highway segments where roadkills occurred to 39 random segments, to see if they differed in the number of culverts and bridges useable by badgers or in the presence or distance covered by Jersey barriers. About 18% of structures in random segments and 40% in roadkill segments were impassable to badgers. Compared to random segments, roadkill-associated segments were less likely to have at least two structures/km passable by badgers (26% of roadkill segments vs. 59% of random segments; χ2 = 8.877, P = 0.003). This supports the notion that badger roadkill risk is lower where an adequate supply of culverts or bridges exists. The presence or amount of Jersey barrier was not related to roadkill risk. This may reflect a lack of effect, or may relate to a difficulty in detecting trends given the few Jersey barriers in our study area and their apparently disproportionate use where badger habitat is poor and where options exist to avoid barriers. Increasing the opportunities for badgers to pass under highways through culverts should reduce mortality and aid recovery. We recommend repairing or retrofitting existing structures, making entrances more visible, installing drift fencing where appropriate, installing more culverts, and investigating culvert or landscape characteristics associated with the use of culverts by badgers.
We photo-verified the presence of a wolverine (Gulo gulo) in California for the first time in 86 years during February 2008. Herein we document the process of determining the origin of this wolverine using genetic, stable carbon (δ13C) and stable nitrogen (δ15N) isotope information. The wolverine's origin was significant because it is a state-threatened species and California represents a historically unique genotype of wolverines in North America. We obtained both photographs and noninvasively-collected genetic evidence (scat and hair). DNA analysis revealed the animal was a male and not a remnant of a historical California population. Comparison with available data revealed the individual was most closely related to populations from the western edge of the Rocky Mountains. This represents the first evidence of connectivity between wolverine populations of the Rocky and Sierra Nevada Mountain Ranges.
Snowfences are specialized windbreaks that divert drifting snow so it will accumulate in a predictable location. They are used commonly in areas with significant snowfall such as the Great Plains and upper mid-west, but are very uncommon in eastern Washington. The purpose of this planting was to display establishment and initial growth in this portion of the country using technologies developed elsewhere. Snowfence demonstrations in southeastern Idaho and a small-scale dry land test plantings near Ritzville, Washington led to an interagency snowfence demonstration project north of Davenport, Washington. The project demonstrated new establishment technology and the value of living snowfences in this dry cropland region. Sixteen snowdrift sites in Lincoln County were identified by road maintenance personnel from the Washington State Department of Transportation. In April 2003, we planted 532 trees and installed fabric mulch on four 268-meter long rows at the selected demonstration site. While the project's primary purpose was to demonstrate feasibility, the trees' yearly growth was also documented. After five years tree height, crown width, and survival rates (100%) were greater than expected, suggesting that living snowfences can be successfully established in this area of the country. Also after five years, the snowfence started to catch drifting snow. The successful establishment and growth of this demonstration planting resulted in living snowfence demonstrations near Anatone, Washington and Athena, Oregon. Landowners and professionals working with landowners were encouraged to incorporate windbreaks into their conservation measures.