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11.
This paper describes the use by family forest landowners of educational programs provided by Washington State University Cooperative Extension (WSUCE), and the associated use of technical assistance programs provided by state and federal agencies and the private sector. Approximately 100,000 family forest owners controlled 19% or over 1.2 M ha of Washington’s forestland and accounted for 29% of the timber harvested in the state on a volume basis in 1998. A variety of public and private assistance and education programs are available to encourage and help family forest owners manage their forests. In 1999 a mail survey was conducted to evaluate use and effectiveness of Washington’s family forest assistance and education programs. Over half of the 872 responding family forest landowners had contact with an extension educator, program or educational material, and about three quarters of these respondents gave an overall rating of the usefulness of extension programs and materials as good or excellent. Respondents attending WSUCE forestry educational programs have larger median land ownership size, are older, have owned their forests longer, have a higher rate of absentee ownership, and are better educated than non-users. They are more likely to actively manage their forests for timber production and exhibit a clearer understanding of the multiple-use capabilities of their forests.  相似文献   
12.
In the Pacific Northwest (PNW) region of the contiguous United States, retention of live (green) trees in harvest units is an integral part of forest management practices on federal lands, yet the ecological benefits that result from various levels or patterns of retained trees remain speculative. The Demonstration of Ecosystem Management Options (DEMO) study was established to address these informational gaps. The experimental design consists of six treatments, each 13 ha in size, replicated at six locations (blocks) in western Washington and Oregon. Treatments represent strong contrasts in retention level (15–100% of original basal area) and pattern (trees dispersed vs. aggregated in 1-ha patches) in mature Douglas-fir (Pseudotsuga menziesii) forests. A wide variety of ecological responses and public perceptions of visual quality have been examined; this paper provides a comprehensive review of the short-term (1–7 years) results of these studies. Level of retention had a strong effect on many responses. At 15% retention, regardless of pattern, microclimate, ecological responses, and public perceptions of visual quality did not differ from those measured in the “clearcut” areas of aggregated treatments. In contrast to level of retention, pattern of retention had limited effect on most measures of biological response. Small changes within forest aggregates were balanced by large changes in adjacent harvested areas, thus on average, responses within aggregated treatments were comparable to those in dispersed treatments. Nevertheless, retaining trees in 1-ha aggregates provided several benefits over dispersed retention. Aggregates greatly reduced damage to and mortality of residual trees (particularly at lower levels of retention) and provided short-term refugia for forest organisms sensitive to disturbance or environmental stress (e.g., bryophytes and late-seral herbs). However, aggregates were susceptible to edge effects (e.g., elevated light and temperature), which may compromise their ability to serve as sources for recolonization of adjacent harvested areas. Collectively, our findings suggest that retention levels >15% are needed to effectively retain sensitive plants and animals, ameliorate harsh microclimatic conditions, and gain public acceptance of retention harvests in these forests. A combination of relatively large (≥1 ha) aggregates and dispersed trees at levels considerably greater than current minimum standards in the PNW may be the most effective strategy for sustaining a broad array of forest values in managed stands.  相似文献   
13.
Amphidromous fish are the biggest contributor to the diversity of fish communities in river systems of Caribbean islands. Among them, Sicydium punctatum Perugia, 1896, which is endemic to the West Indies, represents the vast majority of fish in these rivers. The otolith microstructure and the biometry of S. punctatum postlarvae from Guadeloupe were investigated to explore the dispersal modalities of this species through an appreciation of the growth pattern, the pelagic larval duration (PLD) and the size‐at‐recruitment. The study was made on one cohort of 83 recruited postlarvae, fished at the Capesterre River's mouth on 2 November 2011. The mean (±SD) size‐at‐recruitment of the postlarvae was 24.6 ± 1.3 mm (range of 20.5–28.1 mm, n = 83). We found a mean (±SD) PLD of 72.2 ± 10.5 days (range of 54–101.5 days, n = 67). The growth rate estimated from the otolith increments showed a globally decreasing pattern during the marine larval phase. Growth rates at the beginning of the larval stage were significantly different between hatching periods, suggesting a relation between the hatching period and the growth rate in S. punctatum. This study adds on to the general understanding of the life cycle of S. punctatum in Guadeloupe that will help implement strategies to manage amphidromous fish populations in the Caribbean region.  相似文献   
14.
Stream fish distributions are commonly linked to environmental disturbances affecting terrestrial landscapes. In Great Plains prairie streams, the independent and interactive effects of watershed impoundments and land cover changes remain poorly understood despite their prevalence and assumed contribution to declining stream fish diversity. We used structural equation models and fish community samples from third‐order streams in the Kansas River and Arkansas River basins of Kansas, USA to test the simultaneous effects of geographic location, terrestrial landscape alteration, watershed impoundments and local habitat on species richness for stream‐associated and impoundment‐associated habitat guilds. Watershed impoundment density increased from west to east in both basins, while per cent altered terrestrial landscape (urbanisation + row‐crop agriculture) averaged ~50% in the west, declined throughout the Flint Hills ecoregion and increased (Kansas River basin ~80%) or decreased (Arkansas River basin ~30%) to the east. Geographic location had the strongest effect on richness for both guilds across basins, supporting known zoogeography patterns. In addition to location, impoundment species richness was positively correlated with local habitat in both basins; whereas stream‐species richness was negatively correlated with landscape alterations (Kansas River basin) or landscape alterations and watershed impoundments (Arkansas River basin). These findings suggest that convergences in the relative proportions of impoundment and stream species (i.e., community structure) in the eastern extent of both basins are related to positive effects of increased habitat opportunities for impoundment species and negative effects caused by landscape alterations (Kansas River basin) or landscape alterations plus watershed impoundments (Arkansas River basin) for stream species.  相似文献   
15.
The potential of veterinary antibiotics (VAs) to impact human and environmental health requires the development and evaluation of land management practices that mitigate VA loss from manure-treated agroecosystems. Vegetative buffer strips (VBS) are postulated to be one management tool that can reduce VA transport to surface water resources. The objectives of this study were to (1) investigate oxytetracycline (OTC) and sulfadimethoxine (SDT) sorption to agroforestry buffer, grass buffer, and cropland soils, (2) evaluate differences in VA sorption to soils collected from different vegetative management and soil series, and (3) elucidate relationships between soil properties and VA sorption. Sorption/extraction isotherms for OTC were well-fitted by the Freundlich isotherm model (r 2 > 0.86). OTC was strongly adsorbed by all soils and the VA was not readily extractable. OTC and SDT solid to solution partition coefficients (K d) values are significantly greater for soils planted to VBS relative to grain crops. Significant differences in OTC and SDT K d values were also noted among the soil series studied. Linear regression analyses indicate that clay content and pH were the most important soil properties controlling OTC and SDT adsorption, respectively. Results from this study suggest that agroforestry and grass buffer strips may effectively mitigate antibiotic loss from agroecosystems, in part, due to enhanced antibiotic sorption properties.  相似文献   
16.
Clonal propagation of sugarcane(interspecific hybrids of Saccharum)is conducive to spread of systemicdiseases, such as ratoon stunting disease,caused by Leifsonia xyli subsp. xyli. This important disease iscontrolled by obtaining and plantinghealthy seed-cane. In Louisiana, commercialseed-cane initially produced through tissueculture is available to sugarcane farmersand is being widely planted. Long-termacceptability of this seed-cane productionmethod depends on the production of healthyplants that do not differ significantly inphenotypic and yield characteristics fromthe clones originally selected and releasedas commercial cultivars. To determinewhether tissue culture affects yield or itscomponents, three cultivars, CP 70-321, LCP85-384, and HoCP 85-845, were compared inthree successive crops initially plantedwith stalks from three sources: plantsderived from callus culture of the leafroll above the apical meristem, directregeneration from the apical meristem, andconventional bud propagation. Stalks ofplants derived from both explant sourceswere typical of seed-cane farmers wouldpurchase for planting that had beenpreviously rogued for phenotypic variantsand increased by bud propagation.Differences in yield components amongtissue culture explant sources and budpropagated cane only occurred in CP 70-321.Stalk diameter and stalk weight were lowerand stalk population was higher for plantsderived from leaf roll callus compared tobud propagated cane. Yield components weresimilar for plants derived from an apicalmeristem and bud propagation. Individualplant phenotypic variants resulting fromsomaclonal variation were not observed inany of the cultivars derived from eitherexplant source. In summary, genotype andexplant source affected persistent, uniformphenotypic variation resulting from tissueculture that changed some yield components. However, apical meristem culture wassuitable for production of seed-cane, assugarcane derived by meristem culture ofthree cultivars did not differsignificantly from the original germplasmfor any measured yield trait.  相似文献   
17.
The associations between feeding activities and environmental variables inform animal feeding tactics that maximize energetic gains by minimizing energy costs while maximizing feeding success. Relevant studies in aquatic animals, particularly marine mammals, are scarce due to difficulties in the observation of feeding behaviors in aquatic environments. This data scarcity concurrently hinders ecosystem-based fishery management in the context of small toothed-cetacean conservation. In the present study, a passive acoustic monitoring station was deployed in an East Asian finless porpoise habitat in Laizhou Bay to investigate potential relationships between East Asian finless porpoises and their prey. The data revealed that porpoises were acoustically present nearly every day during the survey period. Porpoise detection rates differed between spring and autumn in concert with activities of fish choruses. During spring, fish choruses were present throughout the afternoon, and this was the time when porpoise vocalizations were the most frequently detected. During autumn, when fish choruses were absent, porpoise detection rates decreased, and diurnal patterns were not detected. The close association between fish choruses and finless porpoise activities implies an “eavesdropping” feeding strategy to maximize energetic gains, similar to other toothed cetaceans that are known to engage similar feeding strategies. Underwater noise pollution, particularly those masking fish choruses, could interrupt finless porpoises’ feeding success. Fisheries competing soniferous fishes with finless porpoise could impact finless porpoise viability through ecosystem disruption, in addition to fishing gear entanglement.  相似文献   
18.
Genome-wide association studies (GWAS) are useful to facilitate crop improvement via enhanced knowledge of marker-trait associations (MTA). A GWAS for grain yield (GY), yield components, and agronomic traits was conducted using a diverse panel of 239 soft red winter wheat (Triticum aestivum) genotypes evaluated across two growing seasons and eight site-years. Analysis of variance showed significant environment, genotype, and genotype-by-environment effects for GY and yield components. Narrow sense heritability of GY (h 2  = 0.48) was moderate compared to other traits including plant height (h 2  = 0.81) and kernel weight (h 2  = 0.77). There were 112 significant MTA (p < 0.0005) detected for eight measured traits using compressed mixed linear models and 5715 single nucleotide polymorphism markers. MTA for GY and agronomic traits coincided with previously reported QTL for winter and spring wheat. Highly significant MTA for GY showed an overall negative allelic effect for the minor allele, indicating selection against these alleles by breeders. Markers associated with multiple traits observed on chromosomes 1A, 2D, 3B, and 4B with positive minor effects serve as potential targets for marker assisted breeding to select for improvement of GY and related traits. Following marker validation, these multi-trait loci have the potential to be utilized for MAS to improve GY and adaptation of soft red winter wheat.  相似文献   
19.
20.
Volatile flavor components of stored nonfat dry milk.   总被引:1,自引:0,他引:1  
Nonfat dry milk (NDM) is widely used both as an ingredient in other preparations and for direct consumption. Flavor quality of NDM is a critical parameter because it can directly impact final product quality. Flavors can be formed in NDM during subsequent storage. Identification of compounds responsible for storage-induced flavors is necessary to correlate sensory quality with potential sources of the flavors. Six NDM samples were selected for volatile flavor analysis based on sensory analysis and storage time. Volatile components were extracted by direct solvent extraction/high vacuum distillation. Volatile extracts were separated into neutral/basic and acidic fractions and analyzed by gas chromatography-olfactometry (GCO) and aroma extract dilution analysis (AEDA). A variety of aldehydes, ketones, and free fatty acids were responsible for generation of flavors in stored NDM. The following compounds exhibited high aroma impact by AEDA: 3-(methylthio)propanal (boiled potato); o-aminoacetophenone (corn tortilla); 2,5-dimethyl-4-hydroxy-3(2H)-furanone and 2-methyl-3-hydroxy-4H-pyran-4-one (burnt sugar); butanoic acid (cheesy); pentanoic acid (sweaty); acetic and hexanoic acids (sour/vinegar); octanoic, decanoic, and dodecanoic acids (waxy); p-cresol (cowy/barny); 3-methylindole (fecal); dimethyl trisulfide (cabbage); (E,E)-2,4-decadienal (fried/fatty); furfuryl alcohol (rubber/vitamin); phenylacetic acid (rose-like); and 1-octen-3-one (mushroom).  相似文献   
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