条斑紫菜离体组织再生苗的研究   总被引：1，自引：0，他引：1  

梅俊学  费修绠 《海洋科学》2000,24(6):39-43

条斑紫菜叶状体离体组织（切块）在一定培养条件下,其营养细胞经过一系列的变化可产生出幼茵。本研究发现切块越小出苗越早、单位面积离体组织出苗量越多。成熟叶状体上靠近雌雄性细胞的区域与其他部位的营养细胞相比形成幼苗较早,离这一区域越远的细胞成苗越晚。离体组织细胞成苗的适宜水温为１５￣１７℃。在２０￣２５℃下部分细胞进行不规则分裂形成深紫红色的细胞团。当降温至１７℃时,它们仍可转化为幼苗。  相似文献   

Interaction between water flow and oxygen deficiency on growth in the infaunal brittle star Amphiura filiformis (Echinodermata: Ophiuroidea)     

H. C. Nilsson 《Journal of Sea Research》2000,44(3-4)

Interactions between ‘oxygen concentration’ (normoxia: >80% oxygen saturation, and hypoxia: 18% oxygen saturation) and ‘water flow velocity’ (low: 0.1 cm s⁻¹, and moderate: 0.5 cm s⁻¹) were studied on growth rates in the brittle star Amphiura filiformis in a flow-through aquaria system. Effects of ‘sublethal predation’ on growth rates were investigated as ‘number of amputated arms’ (1 and 3 arms) and ‘amputation of the disk’. A significant interaction between oxygen concentration and water flow velocity was observed in mean arm regeneration rate, but in both flow velocities higher mean arm regeneration rates were observed in normoxia compared to hypoxia. In hypoxia a positive response in arm regeneration rate was observed in moderate flow compared to low flow velocity. In normoxia, however, no response to flow velocity was observed. The latter observation indicates that Amphiura filiformis is able to maintain the ventilation of the burrow at low flow velocities, but in low oxygen concentrations hydrodynamic forces seem to affect growth. A significant interaction between oxygen concentration and disk amputation was observed in both arm and disk regeneration rates, indicating that the disk is the major organ for gas exchange in this species. The number of arms amputated, however, did not affect mean arm regeneration rate. The results obtained in this study suggest that the secondary production in subtidal infaunal populations could be negatively affected by low oxygen concentrations and that this response is even more negative in combination with low flow velocities in the near-bottom water.  相似文献   

黄海和东海沉积物有机质活性及营养盐再生潜力初探   总被引：9，自引：0，他引：9  

陈建芳  金海燕  刘小涯  李宏亮  林以安  潘建明 《地球化学》2005,34(4):83-90

2000年秋季和 2001年春季,对黄海和东海 6个站位的水柱和沉积物样品进行了营养盐、沉积有机碳、有机碳同位素和氨基酸分析.结果表明, 表层沉积物的有机碳含量和有机质活性存在较明显的季节性变化,这主要由春秋两季表层水体生物量的差异引起.在泥质堆积区 E2、 E4、 E5站,春季表层沉积物有机碳的含量与活性均较高,而同期底部沉积物向上的营养盐梯度也明显增大, 显示有机碳的含量及活性与营养盐再生有密切关系.  相似文献   

微拟球藻原生质体制备与再生     

马晓磊  张琳  杨官品  朱葆华  潘克厚 《海洋科学》2012,36(2):19-23

综合考虑酶混合液处理时间和初始细胞密度两个因素,选取终浓度为4%半纤维素酶和2%崩溃酶的酶混合液对一株海洋经济微藻——微拟球藻(Nannochloropsis oculata)进行原生质体的制备与再生,Calcofluor White染料染色可在荧光显微镜下观察到完整的原生质体细胞。实验结果表明:同一初始密度藻细胞酶处理1～3 h制备率较高;酶处理相同时间较高初始密度(2×107～3×107cells/mL)的藻细胞制备率较高,并且原生质体在再生培养基上可再生,生长趋势与野生型细胞一致。考虑到酶处理时间过长或者密度过大会对原生质体的再生产生影响,本实验选择最适酶处理时间为1h,初始细胞密度为2×107cells/mL。  相似文献   

Disturbance,geomorphic processes and recovery of wildfire slopes in North Tyrol     

Oliver Sass  Michael Heel  Karl‐Friedrich Wetzel  Arne Friedmann 《地球表面变化过程与地形》2012,37(8):883-894

Wildfires in the sub‐alpine belt of the Austrian Limestone Alps sometimes cause severe vegetation and soil destruction with increased danger of secondary natural hazards such as avalanches and debris flows. Some of the affected areas remain degraded to rocky slopes even decades after the fire, raising the question as to whether the ecosystems will ever be able to recover. The mean fire interval, the duration of recovery and the role of geomorphic processes for vegetation regeneration are so far unknown. These questions were tackled in a broad research approach including investigation of historical archives to determine the frequency of historical wildfires, mapping vegetation regeneration on 20 slopes of different post‐fire ages, and soil erosion measurements on two slopes. To date, > 450 historical wildfires have been located in the study area. The mean fire interval per square kilometre is c. 750 years, but can be as low as 200–500 years on south‐facing slopes. Vegetation regeneration takes an extremely long time under unfavourable conditions; the typical window of disturbance is between 50 and 500 years, which is far longer than in any other wildfire study known to us. Soil erosion constantly increases in the years after the fires and the elevated intensity can be maintained for decades. A two‐part vegetation regeneration model is proposed depending upon the degree of soil loss. In the case of moderate soil erosion, spreading grassland communities can slow down shrub re‐colonization. In contrast, after severe soil destruction the slopes may remain degraded for a century or longer, before rather rapid regeneration occurs. The reasons are not fully understood but are probably governed by geomorphic process intensity. The interdependence of vegetation regeneration and geomorphic processes is a paradigm of ecology–geomorphology interaction, and is a unique example of a very long‐lasting disturbance response caused by wildfire in a non‐resilient ecosystem. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Land use/cover, landforms and fragmentation patterns in a tropical dry forest in the southern Pacific region of Mexico   总被引：1，自引：0，他引：1  

Leopoldo Galicia  Alba Esmeralda Zarco-Arista  Karla Ivette Mendoza-Robles  José Luis Palacio-Prieto  Arturo García-Romero 《Singapore journal of tropical geography》2008,29(2):137-154

In spite of widely documented studies of deforestation rates and land use/cover changes in tropical dry forests in Mexico, relatively little is known about fragmentation patterns in such forests. This study defines the spatial distribution of landforms and land use/cover types the lower Papagayo River basin and examines their influence on fragmentation patterns and biological diversity in a tropical dry forest in that southern Pacific region. The land use/cover map was constructed from aerial photographs, Landsat TM imagery (2000) and fieldwork. Landform units were defined based on altitude, slope, lithology and morphology. Landscape fragmentation parameters were obtained using FRAGSTATS (version 3.3) considering the numbers of patches, mean, minimum and maximum patch size, edge density, total edge and connectivity. Results show tropical dry forest to be remnant vegetation (~11 per cent), characterized by isolation and low connectivity. Land use/cover types have different effects on fragmentation patterns. Agriculture and cattle raising produce similar numbers of patches, but with a different mean size; and human settlements have a scattered distribution pattern. The abandonment of rural agricultural livelihoods has favoured the expansion of secondary tropical dry forest characterized by continuity and high connectivity, which suggests a high regeneration potential from land abandonment. It can be concluded that tropical dry forest fragmentation and recovery at regional scales depend on such landscape attributes as lithology, slope, geomorphology and management.  相似文献   

Tree Planting:How Fast Can It Accelerate Post-fire Forest Restoration?——A Case Study in Northern Da Hinggan Mountains,China     

LI Xiuzhen  HE Hong S  WANG Xugao  XIE Fuju  HU Yuanman  LI Yuehui 《中国地理科学(英文版)》2010,20(6):481-490

In 1987,a catastrophic fire burned over 1330000 ha in the densely forested area of the Da Hinggan Mountains in the northeastern China.After the fire,intensive management including burned trunk harvesting and coniferous tree planting had been conducted to accelerate forest restoration.To study the long term effect of these activities on forest recovery,we used a simulation modeling approach to study long-term(300 years) forest dynamics under current planting and natural regeneration scenarios.Results indicat...  相似文献   

水空间管理与水资源的可持续性   总被引：26，自引：12，他引：14  

邓伟  翟金良  闫敏华 《地理科学》2003,23(4):385-390

水资源的赋存需要特定的空间结构,水空间对于维系水资源系统的完整性、保障水循环和水资源的可再生能力、实现水资源的可持续开发利用具有重要作用。 由于人类活动极大地干扰了地球表层系统,水空间结构遭到严重破坏,破坏了水资源支撑社会经济发展的可持续能力。水空间的丧失极大地改变了流域尺度上的水循环过程,加剧了水资源的负均衡性。科学规划水空间,建立水资源安全的水空间格局和预警系统,以实现水资源的可持续性利用,保障资源、环境与社会经济协调发展。  相似文献   

非表征理论视角下的城市再生方式——广州创新创业空间案例     

赵美婷  王泳捷  沈珺琳  江荣灏  王敏 《世界地理研究》2020,29(4):834-844

以非表征理论为切入点，本文以广州创新创业空间为案例，探讨情感空间和身体等要素在促进城市再生进程中的作用。研究发现：各主体在孵化器/众创空间的建设发展过程中邂逅，通过身体实践作用于物质空间构成创新创意空间关系网络和城市再生体系，重构创新创业空间的文化内涵并培育创新情感和创造行为，为创意产业的发展和地方感的重构提供物质基础以及赋予其多元的地方意义。而后，创意阶层的日常生活实践重塑了社区环境促进微空间的再生产，实现资本积累以完成第一轮时空修复，并随着其社会影响范围的扩大成为新城市文化，促进第二轮时空修复的完成。上述结论回应了非表征理论看待世界的方式和填补了非表征理论在宏观尺度研究上的空缺，为城市再生提供了新的实践切入点。  相似文献   

考虑剩余剪应力的滑带土强度再生试验          下载免费PDF全文

王辉  高东源  吴博 《中国地质灾害与防治学报》2020,31(1):102-106

用改造的直剪仪研究了滑带土再生强度与滑动面剩余剪应力比PRSS和强度再生时间的关系。结果表明,滑带土强度再生与上覆滑体压应力关系不大,但较高的剩余剪应力比PRSS妨碍滑带土强度再生,滑带土强度有效再生的界限PRSS在55%到70%之间。剩余剪应力比PRSS小于等于55%时,90 d时滑带土再生强度可达到慢剪强度的70%以上,PRSS大于等于70%时,90 d时滑带土再生强度不足慢剪强度的25%。滑带土强度再生过程中,黏聚力和内摩擦角增速不一致,PRSS小于等于55%时,黏聚力C在前30 d增速较快,30 d时增至慢剪强度[C]的44.6%,此后增速均明显放缓,90 d时其值为慢剪强度[C]的49%。内摩擦角φ在前90 d增速基本一致,90 d时其值占慢剪强度[φ]的90.4%。黏聚力和内摩擦角90 d以后均趋于稳定。  相似文献