Lifting and storing bareroot blue oak (Quercus douglasii) seedlings

In California today, several species of native oaks are not regenerating adequately. Artificial regeneration is a means of ensuring sufficient recruitment to replace trees that die or are harvested, and restoring areas where trees have been cleared. Until recently, however, no bareroot oak seedlings were being produced in the state and there was little information to guide nursery operators. This study evaluated the potential of bareroot blue oak seedlings to survive and grow after outplanting. Results indicated that 1-0 nursery stock performed well in the field as long as seedlings were planted early enough in the season to take advantage of a favorable growing environment. Late lifting and long storage resulted in planting at a time when soils were already becoming dry and temperatures were hot. As a result, seedlings grew slowly or even died. Seedlings lifted early in the season (December) grew best. Either one or two months of storage had little effect on seedlings lifted at this time of year. However, seedlings lifted in January, February, and even early March performed adequately as long as they were in the ground by early March. In this study, root growth capacity was not a good predictor of subsequent field performance.     

The effects of collection date and pre-storage treatment on the germination of blue oak acorns

Concern about poor natural regeneration of blue oak in California has prompted efforts to artificially regenerate this species. Two studies examined the best time to collect acorns and the effect various pre-storage treatments, including soaking and drying, have on germination. Results indicated that acorns can be successfully collected over a fairly wide interval, extending from late August until late October. Acorns from all harvest dates had high germination, as long as they were not allowed to dry out before storage. However, the earlier the acorns were collected, the earlier they tended to germinate. Soaking acorns for a day prior to storage had little effect. Drying acorns, however, reduced both the rate and amount of germination. A 10% reduction in moisture content resulted in almost 40% less total germination, and all acorns that lost 25% or more of their mositure failed to germinate during the 10-week test interval. To ensure good seed quality, blue oak acorns should be collected directly from tree branches and placed immediately in cold storage.     

Predicting field performance of Douglas-fir seedlings: comparison of root growth potential,vigor and plant moisture stress

Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings were evaluated- by three measurements of seedling quality — root growth potential or RGP, vigor, and plant moisture stress or PMS — and the results were correlated with subsequent field performance. Measurements made by each method were significantly (p 0.05) correlated with first- and second-year survival and terminal height growth. Seedlings from lots that grew many new roots during a 28-day interval in a growth room (RGP evaluation) or that survived for 6 weeks in the growth room and initiated rapid budburst (vigor evaluation) or whose plant moisture stress values remained fairly constant during 1 week after potting (PMS evaluation) had the greatest field survival and height growth.The RGP evaluation was the best predictor of first-year height growth, while the vigor evaluation was the best predictor of first- and second-year survival. All evaluations predicted second-year height growth equally well.These results demonstrate that all three evaluations can be successfully used to predict field performance of Douglas-fir seedlings. Each has its advantages and limitations, and none can be considered best. The one used should be selected on the basis of time constraints, equipment and resources available, and specific objectives, such as whether it is considered more important to estimate field survival or growth.When this research was conducted, both authors were affiliated with the Department of Forest Science, College of Forestry, Oregon State University, Corvallis, OR 97331, USA. Mention of commercial products does not imply endorsement by Oregon State University. This is Paper 2145 of the Forest Research Laboratory, Oregon State University.     

Estimation of metademographic rates and landscape connectivity for a conservation-reliant anuran

Landscape Ecology - Amphibian conservation efforts commonly assume populations are tied to waterbodies that collectively function as a metapopulation. This assumption is rarely evaluated, and there...     

Mercury-Resistant Bacteria Associated With Macrophytes from A Polluted Lake

Although Onondaga Lake in the Syracuse NY area is contaminated with high levels of mercury from past manufacturing operations, macrophytes in the lake have been able to survive, apparently withstanding mercury toxicity. Homogenates of three macrophyte species, Myriophyllum spicatum L., Potamogeton crispus L., and Stuckenia pectinata (L.) Borner, were phenotypically positive for the presence of mercury resistant bacteria. As determined by PCR analysis, the mercury resistant bacteria associated with M. spicatum and S. pectinata also possessed merA, one of the more widely studied essential genes in the mer operon. Analysis of 24 macrophyte taxa isolated from lakes across the United States, as well as biological supply houses, showed that mercury resistant bacteria were associated with all macrophytes. One possible explanation for the association of mercury resistant bacteria with macrophytes is described. This hypothesis suggests that Hg ^r bacteria may potentially ameliorate the negative effects that mercury elicits in macrophytes.