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Field experiments were conducted to characterize the demography of Abutilon theophrasti and Setaria faberi in a conventionally managed 2‐year (maize/soya bean) rotation, and in 3‐year (maize/soya bean/triticale + red clover) and 4‐year (maize/soya bean/triticale + lucerne/lucerne) rotations managed with 72% and 79% lower herbicide inputs respectively. Rates of weed seedling recruitment, seedling survival and adult plant fecundity were determined for populations in each phase of each rotation and used to calculate annual rates of weed population change, Δ. In both years of the study, Δ for A. theophrasti populations declined or remained stable in all three rotation systems. Despite greater rates of seedling survival and fecundity in maize and soya bean in the 3‐ and 4‐year rotations, increases in Δ for A. theophrasti populations were prevented in these systems because of low fecundity in triticale and low seedling survival and fecundity in lucerne. For Setaria faberi populations, Δ remained stable in the 2‐year rotation, increased in the 3‐year rotation in both years, and increased in the 4‐year rotation in 1 year. The results of this study indicate that when herbicide use is reduced, rotations that include triticale and lucerne can facilitate the suppression of A. theophrasti. Rotations that include lucerne can contribute to restraining S. faberi population growth, given adequate levels of seedling mortality in this crop. 相似文献
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松嫩平原羊草草地水淹干扰恢复过程的群落动态 总被引:16,自引:6,他引:10
根据随机取样的测定数据,经过幂函数和多元回归分析及相关检验,揭示了草地水淹干扰对羊草 寸草苔、羊草 杂类草群范数量性状的变化规律。水淹干扰对草地植被的物种组成及其比例有明显的影响。水淹后基本恢复到正常草地的种类数量和生产量配置大约需要6—7年。随着生境水分减少和土壤变干,羊草种群的数量和生物量均以幂函数形式增加,而寸草苔和杂类草的数量和生物量则呈先增后降的变化过程。 相似文献
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Summary The segregation of RFLP and RAPD markers was compared in two oilseed rape (Brassica napus L.) breeding populations from the cross Topas x R4, the latter being a low linolenic mutation line. A total progeny of 68 F2 and 40 microspore derived plants were studied with 25 markers. The results indicated a significant excess of Topas alleles at five RAPD loci in the microspore derived population. This suggests that genomic regions which probably affect microspore culture ability do not have identical distribution in the two population types. 相似文献
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C肉毒杀鼠素在高寒草甸地区灭鼠技术中的应用 总被引:2,自引:0,他引:2
综述C肉毒杀鼠素草原灭鼠应用技术,充分肯定了C肉毒杀鼠素毒力强、适口性好、对非靶动物毒性低、作用缓慢、无二次中毒、易降解和适合规模灭鼠的特点,为鼠害防治提供了新的思路。 相似文献
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The influence of sampling scheme and interpolation method on the power to detect spatial effects of forest birds in Ontario (Canada) 总被引:1,自引:0,他引:1
Spatial ecology is becoming an increasingly important component of resource management, and the general monitoring of how
human activities affect the distribution and abundance of wildlife. Yet most work on the reliability of sampling strategies
is based on a non-spatial analysis of variance paradigm, and little work has been done assessing the power of alternative
spatial methods for creating reliable maps of animal abundance. Such a map forms a critical response variable for multiple
scale studies relating landscape structure to biotic function. The power to reconstruct patterns of distribution and abundance
is influenced by sample placement strategy and density, the nature of spatial auto-correlation among points, and by the technique
used to extrapolate points into an animal abundance map. Faced with uncertainty concerning the influence of these factors,
we chose to first synthesize a model reference system of known properties and then evaluate the relative performance of alternative
sampling and mapping procedures using it. We used published habitat associations of tree nesting boreal neo-tropical birds,
a classified habitat map from the Manitou Lakes area of northwestern Ontario, and point count means and variances determined
from field studies in boreal Canada to create 4 simulated models of avian abundance to function as reference maps. Four point
sampling strategies were evaluated by 4 spatial mapping methods. We found mixed-cluster sampling to be an effective point
sampling strategy, particularly when high habitat fragmentation was avoided by restricting samples to habitat patches >10
ha in size. We also found that of the 4 mapping methods, only stratified ordinary point kriging (OPK) was able to generate
maps that reproduced an embedded landscape-scale spatial effect that reduced nesting bird abundance in areas of higher forest
age-class fragmentation. Global OPK was effective only for detecting broader, regional-scale differences.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献