Reeds are widely distributed in drought and high salt conditions of northwestern China. Leaf epidermal micromorphology, anatomy, chloroplast ultrastructure and physio-chemical characteristics due to long-term adaptati...Reeds are widely distributed in drought and high salt conditions of northwestern China. Leaf epidermal micromorphology, anatomy, chloroplast ultrastructure and physio-chemical characteristics due to long-term adaptation in the natural habitats of common reed （Phragmites communis Trin.） contrasted considerably among three different ecotypes： dune reed （DR）, Gobi salt reed （GSR） and swamp reed （SR）. The main objective of the present study is to determine the adapting characteristics of morphology, anatomy and physiological responses of thin roots in DR, GSR and SR. The results show that root length density was higher in SR and few root hairs were observed in DR. Cross-section anatomical features show that each ecotype has an endodermis and exodermis, while cortex thickness and proportion of root cortical aerenchyma and stele in root structure varied among the three ecotypes. The stele and xylem share a larger area in DR compared to GSR and SR. GSR has a large proportion of the cortex with radialized distribution of aerenchyma cells spacing, and the cortex has a peripheral, mechanically stiff ring in the exodermis. SEM and TEM microscope images show that GSR has a scle- renchyma ring with high lignification in the exodermis. The physio-chemical parameters show that GSR had a higher level of stress tolerance than DR. These findings indicate that developed water-absorbing tissues were largely distributed in the root structure of DR, and a main framework with supporting function spacing with aerenchyma was dominant in GSR in the long term adaptation to their natural habitats, respectively.展开更多
基金financially supported by the State Key Development Program for Basic Research of China(973 Program,Grant No.2013CB429904)the National Natural Science Foundation of China(Grant No.91125029)
文摘Reeds are widely distributed in drought and high salt conditions of northwestern China. Leaf epidermal micromorphology, anatomy, chloroplast ultrastructure and physio-chemical characteristics due to long-term adaptation in the natural habitats of common reed （Phragmites communis Trin.） contrasted considerably among three different ecotypes： dune reed （DR）, Gobi salt reed （GSR） and swamp reed （SR）. The main objective of the present study is to determine the adapting characteristics of morphology, anatomy and physiological responses of thin roots in DR, GSR and SR. The results show that root length density was higher in SR and few root hairs were observed in DR. Cross-section anatomical features show that each ecotype has an endodermis and exodermis, while cortex thickness and proportion of root cortical aerenchyma and stele in root structure varied among the three ecotypes. The stele and xylem share a larger area in DR compared to GSR and SR. GSR has a large proportion of the cortex with radialized distribution of aerenchyma cells spacing, and the cortex has a peripheral, mechanically stiff ring in the exodermis. SEM and TEM microscope images show that GSR has a scle- renchyma ring with high lignification in the exodermis. The physio-chemical parameters show that GSR had a higher level of stress tolerance than DR. These findings indicate that developed water-absorbing tissues were largely distributed in the root structure of DR, and a main framework with supporting function spacing with aerenchyma was dominant in GSR in the long term adaptation to their natural habitats, respectively.
文摘河流以一定的边界形态承载着水流及物质的输移,受现场量测困难、水文观测站点有限及数字高程模型(digital elevation model,DEM)精度限制,导致分布在江河源区、山区和偏远地区的细小河流断面信息积累极为匮乏,阻碍了河流水文、水动力过程等方面的研究。国际水文协会(IAHS)自本世纪初力倡解决无测站流域水文预测难题,使得高精度提取无测站流域河流水文信息变得越来越重要。ICESat-2 (ice,cloud and land elevation satellite-2)卫星测高任务具有在缺资料地区采集高密度地表点云的能力。该文以黄河中游一级支流皇甫川流域缺资料地区河宽小于10m的细小河流为研究对象,提出了一种利用ICESat-2 ATL03数据提取山区细小河流断面形态的方法。通过光子点云中、高置信度选择、平滑滤波去噪处理和DEM构建,提取了3个不同点位细小河流断面形态并与无人机原位测量结果进行对比分析。结合中、高置信度点云选择和滤波去噪可以有效地去除光子点云噪声,去噪率在63%以上;基于ATL03数据提取的地面点完整度和丰富度优于利用ATL08产品对ATL03分类得到的地面点;基于ATL03数据提取的河流断面形态结果与无人机原位测量结果基本一致(R^(2)>0.96,RMSE=0.69m)。研究结果初步证明了ICESat-2测高数据用于缺资料地区细小河流断面提取的可行性,可为全流域三维河网构建、水文水动力过程模拟等提供技术支持。
