油松球果小卷蛾化蛹行为     

王法  赵战岭  郭鸿儒  孙凡 《东北林业大学学报》2021,49(1):129-131

为了有效防治油松球果小卷蛾(Gravitarmata margarotana)对红松(Pinus koraiensis)的危害,在实验室内对其化蛹行为进行了研究。结果表明:油松球果小卷蛾幼虫无自发的聚集化蛹行为;在土壤及松针中幼虫均能结丝茧并在其中化蛹,但在光滑的容器里不能启动结茧行为,从而化蛹失败。光照对幼虫在土中化蛹场所的选择有影响,在暗区化蛹的数量明显高于光照区;土壤结构对幼虫化蛹场所的选择无影响,在壤土和沙土中化蛹的数量无明显差别。  相似文献   

Saiga antelope calving site selection is increasingly driven by human disturbance   总被引：1，自引：0，他引：1  

N.J. Singh  I.A. Grachev  E.J. Milner-Gulland 《Biological conservation》2010,143(7):1770-1779

Many terrestrial mammalian species aggregate to give birth. Such aggregations are likely to be a response to changing resource and water availability, for predator swamping and avoidance of disturbance. The critically endangered saiga antelope (Saiga tatarica) is one such species. We analysed spatio-temporal locations of saiga calving aggregations in Kazakhstan over the last four decades obtained from aerial and ground surveys, to identify the factors determining the selection of calving sites within the species’ range as well as any changes in these locations over time. Generalized mixed models were employed in a use - availability framework to assess the factors distinguishing calving from random sites and predict suitable areas for calving. Saigas selected sites, with lower than average productivity and low year to year variability in productivity, at an intermediate distance from water sources, and away from human settlements. A significant change in calving locations was observed during the last decade, with calving areas occurring further north and further away from settlements than previously. The results demonstrate that the choice of calving areas is largely driven by environmental factors. However, disturbance also has a significant impact on calving site selection and in recent decades, its influence overrides that of environmental factors. This increase in the influence of disturbance coincides with a precipitous decline in saiga numbers due to poaching, as well as substantial reductions in the intensity of land use for livestock grazing following the breakup of the Soviet Union. Predictive models based on such studies can improve species conservation by guiding the stratification of sampling for effective monitoring and deployment of rangers to protect the females at this critical time.  相似文献   

Resilience of microorganisms and aggregation of a sandy calcareous soil to amendment with organic and synthetic fertilizer     

M. K. Thorsen  D. W. Hopkins  S. Woodward  B. M. McKenzie 《Soil Use and Management》2010,26(2):149-157

Marginal coastal soils are dependent on appropriate land management to prevent soil erosion, as a result of low soil stability combined with exposure to strong winds. An example of such an area is the machair, a fixed dune system utilized for agriculture in the northwest of Scotland, UK. The separate and combined effects of synthetic NPK fertilizer and a traditional soil conditioner (kelp, a seaweed) on soil structure formation, stabilization and biological parameters were studied on a cropped field on the machair. Soil physical properties examined included water retention at 10 kPa matric suction, water stable aggregates (WSA) >1 mm, aggregate stability, and biological properties including ester-linked fatty acid (ELFA) analysis and β-glucosidase activity for microbial biomass and activity, respectively. Significant treatment effects were few and inconsistent between sampling times, but included kelp and/or NPK fertilizer reducing aggregation, water retention, microbial biomass and activity relative to the unamended control treatment. Furthermore, seasonal variation, which could be attributed to changes in soil water content, was stronger than variation in response to fertilizer treatments. Principal components analysis of the ELFA data showed that ploughing promoted fungal biomass relative to bacteria, and confirmed both the absence of consistent synthetic and organic fertilizer effects and the sensitivity of microbial biomass to season. Overall, the study demonstrated the resilience of a calcareous sandy soil to amendment with fertilizer.  相似文献   

大棚黄瓜上烟粉虱成虫动态研究   总被引：1，自引：0，他引：1  

沈斌斌  MUSA P D  任顺祥 《安徽农业科学》2007,35(11):3299-3300

对大棚烟粉虱成虫动态进行了研究.结果表明:烟粉虱成虫的聚集强度随密度的上升而下降;成虫始终处于聚集-扩散-再聚集-再扩散的动态过程之中.烟粉虱成虫在黄瓜植株上部充分展开的幼嫩叶片上数量最大;烟粉虱在大棚黄瓜上呈指数增长,其模型为Nt=2.5642e0.532t,(r=0.9858**).应用最优分割法将烟粉虱成虫动态划分为3个时期,分别为建立期、发展期和暴发期,在种群建立期对烟粉虱实施控制可以获得最佳的效果.  相似文献   

Microbiota accompanying different arbuscular mycorrhizal fungal isolates influence soil aggregation     

Matthias C. Rillig  Emily R. Lutgen  Philip W. Ramsey  John N. Klironomos  James E. Gannon 《Pedobiologia》2005,49(3):43

Arbuscular mycorrhizal fungi (AMF) are key components of ecosystems through their influence on plant communities and ecosystem processes. A major source of information regarding the importance of AMF species richness on process rates are mesocosm experiments using different levels of diversity of AMF as provided by single-species cultures of AMF. Since AMF inocula are generally made available in the form of non-sterile pot culture material, it is possible that AMF symbiosis-associated microbiota are at least partially responsible for some effects hitherto directly attributed to the AMF mycelium. Here, we provide evidence that microbiota associated with single-species cultures of AMF (after long-term pot culture enrichment of 7–8 years) can strongly affect the ecosystem process of soil aggregation. This effect occurred in an AMF isolate specific manner, but in the absence of live and active AMF mycelium. We additionally documented large differences in microbiota communities associated with the different AMF inocula (using PLFA analyses), suggesting that these differences were at least partly responsible for the observed changes in soil aggregation. This result points to AMF–microbiota interactions as a largely unexplored mechanism underlying soil aggregation (and potentially other ecosystem processes). We suggest that a reinterpretation of previous experiments using greenhouse-derived AMF cultures may be necessary, and the need to consider AMF symbiosis-associated microbiota in mechanistic studies of AMF and mycorrhizae in general is emphasized.  相似文献   

Protection of soil carbon by microaggregates within earthworm casts     

Heleen Bossuyt  Johan Six 《Soil biology & biochemistry》2005,37(2):251-258

Earthworms are known to play a role in aggregate formation and soil organic matter (SOM) protection. However, it is still unclear at what scale and how quickly earthworms manage to protect SOM. We investigated the effects of Aporrectodea caliginosa on aggregation and aggregate-associated C pools using ¹³C-labeled sorghum (Sorghum bicolor (L.) Moench) leaf residue. Two incubations were set up. The first incubation consisted of soil samples crushed <250 μm to break up all macroaggregates with three treatments: (i) control soil; (ii) soil+¹³C-labeled residue and (iii) soil+¹³C-labeled residue+earthworms. Earthworms were added after 8 d and 12 d (days) later, aggregate size distribution was measured together with total C and ¹³C in each aggregate fraction. A second incubation was made to assay protected versus unprotected total C and ¹³C from 21-d laboratory incubations of intact and crushed large (>2000 μm) and small (250-2000 μm) macroaggregates and microaggregates (53-250 μm). Eight different pools of aggregate-associated C were quantified: (1) and (2) unprotected C pools in large and small macroaggregates, (3) unprotected C pools in microaggregates, (4) and (5) protected C pools in large and small macroaggregates, (6) protected C pool in microaggregates, and (7) and (8) protected C pools in microaggregates within large and small macroaggregates. In the presence of earthworms, a higher proportion of large macroaggregates was newly formed and these aggregates contained more C and ¹³C compared to bulk soil. There were no significant differences between the samples with or without earthworms in the C pool-sizes protected by macroaggregates, microaggregates or microaggregates within small macroaggregates. However, in the presence of earthworms, the C protected by microaggregates within large macroaggregates was a significant pool and 22% of this C pool was newly added C. In conclusion, these results clearly indicate the direct involvement of earthworms in providing protection of soil C in microaggregates within large macroaggregates leading to a possible long-term stabilization of soil C.  相似文献   

马尾松舞毒蛾卵块空间分布型及其应用的研究     

干文奎  黄祖惠 《西南林学院学报》1991,11(2):221-225

马尾松舞毒蛾卵块的空间分布型,用聚集度指标度量适合聚集分布。Iwao的回归分析法与Taylor幂法则也是确定聚集型分布的好方法,结果都说明是聚集型的。由此可确定抽样调查的最适抽样数,编制序贯抽样分析表,用于预测预报和防治效果的检验。  相似文献   

卧龙自然保护区功能区的模糊划分   总被引：5，自引：0，他引：5  

史军义  史蓉红 《四川林业科技》1998,19(1):6-16

自然保护区功能区的划分是保护区规划和建设的一项十分重要的基础工作。长期以来,我国自然保护区功能区的划分一直采用人为定性划分方法,主观随意性较大,缺乏科学依据。卧龙自然保护区的功能区,是１９８４年人为确定以磨子沟大桥为界,以西划为核心区,以东划为试验区。实践证明,这种划分不符合卧龙的实际,结果未能发挥出功能区划分应有的作用,本文在大量调查,计算和分析的基础上,选择出旅游、农业活动、距离公路的远近,海  相似文献   

大豆蛋白酶解物的抗消化性及离子强度对其聚集的影响     

张彬  刘贺  徐婧婷  郭顺堂 《大豆科学》2011,30(4):632-637

分别采用体积排阻色谱和Folin-酚法测定了经酸性蛋白酶(蛋白酶M、胃蛋白酶)、中性蛋白酶(蛋白酶A、蛋白酶N)、枯草杆菌碱性蛋白酶Alcalase酶解后制得的大豆肽经过模拟体内消化之后分子量的变化,以及离子强度对酶解物聚合的影响.大豆肽的高效液相色谱体积排阻色谱图显示,50％左右的大豆肽的分子量集中在10～30 kD...  相似文献   

Soil organic carbon and aggregation under poplar based agroforestry system in relation to tree age and soil type     

Naveen Gupta  S. S. Kukal  S. S. Bawa  G. S. Dhaliwal 《Agroforestry Systems》2009,76(1):27-35

The poplar based agroforestry system improves aggregation of soil through huge amounts of organic matter in the form of leaf biomass. The extent of improvement may be affected by the age of the poplar trees and the soil type. The surface and subsurface soil samples from agroforestry and adjoining non-agroforestry sites with different years of poplar plantation (1, 3 and 6 years) and varying soil textures (loamy sand and sandy clay) were analyzed for soil organic carbon, its sequestration and aggregate size distribution. The average soil organic carbon increased from 0.36 in sole crop to 0.66% in agroforestry soils. The increase was higher in loamy sand than sandy clay. The soil organic carbon increased with increase in tree age. The soils under agroforestry had 2.9–4.8 Mg ha⁻¹ higher soil organic carbon than in sole crop. The poplar trees could sequester higher soil organic carbon in 0–30 cm profile during the first year of their plantation (6.07 Mg ha⁻¹ year⁻¹) than the subsequent years (1.95–2.63 Mg ha⁻¹ year⁻¹). The sandy clay could sequester higher carbon (2.85 Mg ha⁻¹ year⁻¹) than in loamy sand (2.32 Mg ha⁻¹ year⁻¹). The mean weight diameter (MWD) of soil aggregates increased by 3.2, 7.3 and 13.3 times in soils with 1, 3 and 6 years plantation, respectively from that in sole crop. The increase in MWD with agroforestry was higher in loamy sand than sandy clay soil. The water stable aggregates (WSA >0.25 mm) increased by 14.4, 32.6 and 56.9 times in soils with 1, 3 and 6 years plantation, respectively, from that in sole crop. The WSA >0.25 mm were 6.02 times higher in loamy sand and 2.2 times in sandy clay than in sole crop soils.  相似文献