Pollen morphology of selected tundra plants from the high Arctic of Ny-(A)lesund, Svalbard     

YAO Yifeng  ZHAO Qi  BERA Subir  LI Xiaoli  LI Chengsen 《极地研究(英文版)》2012,23(2):103-115

Documenting morphological features of modem pollen is fundamental for the identification of fossil pollen, which will assist researchers to reconstruct the vegetation and climate of a particular geologic period. This paper presents the pollen morphol- ogy of 20 species of tundra plants from the high Arctic of Ny-Alesund, Svalbard, using light and scanning electron microscopy. The plants used in this study belong to 12 families： Brassicaceae, Caryophyllaceae, Cyperaceae, Ericaceae, Juncaceae, Papav- eraceae, Poaceae, Polygonaceae, Ranunculaceae, Rosaceae, Salicaceae, and Scrophulariaceae. Pollen grain shapes included： spher- oidal, subprolate, and prolate. Variable apertural patterns ranged from 2-syncolpate, 3-colpate, 3-（-4）-colpate, 3-（-5）-colpate, 3-colporate, 5-poroid, ulcerate, ulcus to pantoporate. Exine ornamentations comprised psilate, striate-perforate, reticulate, mi- croechinate, microechinate-perforate, scabrate, granulate, and granulate-perforate. This study provided a useful reference for com- parative studies of fossil pollen and for the reconstruction of paleovegetation and paleoclimate in Svalbard region of Arctic.  相似文献   

Nitrogen Uptake and Use Efficiency of Invasive Spartina alterniflora and Native Phragmites australis: Effect of Nitrogen Supply          下载免费PDF全文

Hua Qing  Ying Cai  Yan Xiao  Yihan Yao  Shuqing An 《洁净——土壤、空气、水》2015,43(2):305-311

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吐哈盆地北缘中侏罗世植物化石稳定碳同位素的古环境意义   总被引：2，自引：1，他引：1  

肖良  漆亚玲  马文忠  李相传  郭俊锋  孙楠  姚肖永 《沉积学报》2017,35(3):489-498

新疆吐哈盆地北缘三道岭煤田中侏罗统西山窑组的植物化石属于Coniopteris-Phoenicopsis植物群的典型组合。从该植物群中挑选出优势属种,分别为似银杏、拟刺葵、枝脉蕨以及斯堪尼狭轴穗,对其进行稳定碳同位素分析。前3种为叶片化石,它们的δ13C值分布在-21.66‰~-23.83‰,属于典型的C3植物。最后一种为繁殖器官化石,其δ13C值为-20.91‰,比叶片的值高。将δ13C值根据公式转换为大气CO₂的δ13C_a值,发现基于银杏类叶片获得的现代和中侏罗世的δ13C_a值与其他方法获得的值相似。这说明银杏类叶片是重建地质历史时期δ13C_a的一类可靠植物,为今后研究中生代-新生代δ13C_a变化提供了一个简便而可行的方法。C_i/C_a比值是一重要的植物生理生态特征值,因此进一步将银杏类化石叶片的δ13C值换算成C_i/C_a。化石似银杏的C_i/C_a值为0.6,而现生银杏的C_i/C_a为0.63,二者相似。虽然三道岭地区中侏罗世的CO₂浓度约为现在的4.5倍,但是化石和现生银杏类植物的C_i/C_a值仍然保持恒定,表明银杏植物的气孔参数对CO₂变化比较敏感,是重建古CO₂浓度的良好指示植物。这也为判断一种植物能否用来重建古CO₂浓度提供了一种简便而有效的检测方法。  相似文献   

喀斯特适生植物固碳增汇策略   总被引：5，自引：1，他引：4  

吴沿友 《中国岩溶》2011,30(4):461-465

通过分析喀斯特地区的土壤化学性质,明确了喀斯特地区植物的固碳增汇的限制因素为岩溶干旱、低营养、高pH、高重碳酸盐等。通过对喀斯特适生植物和非适生植物的无机碳源、氮源的利用以及对低营养的响应差异分析,总结出了喀斯特适生植物交替、高效利用碳酸氢根离子作碳源的开源固碳增汇策略,以较低的营养成本获取较高的光合固碳能力的低成本倍增固碳增汇策略,以及掠夺式吸收限制性的铵态氮和补偿式吸收硝态氮来实现固碳增汇作用的以氮增汇策略等;提出了喀斯特适生植物固碳增汇能力的利用途径,可最大限度挖掘出喀斯特地区植物的固碳增汇潜能。   相似文献   

An Ex Situ Salinity Restoration Assessment Using Legume,Saltbush, and Grass in Australian Soil          下载免费PDF全文

Mohammad S. I. Bhuiyan  Anantanarayanan Raman  Dennis Hodgkins  David Mitchell  Helen Nicol 《洁净——土壤、空气、水》2016,44(7):840-848

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Saguaro Distribution under Nurse Plants in Arizona's Sonoran Desert: Directional and Microclimate Influences*     

《The Professional geographer》2013,65(4):505-512

Abstract

The saguaro cactus, an icon of the American southwestern desert, defines the extent of the Sonoran Desert through portions of its range. Saguaros rely upon nurse plants for establishment and survival in the harsh temperature and moisture regime of the desert. Freezing temperatures limit the range of the saguaro to the north in Arizona. However, nurse plants extend the range of saguaros by providing more moderate conditions beneath their canopies. This study focuses on precisely these small, highly localized temperature variations, which, we suggest, are linked to regional-scale patterns of distribution of the species, particularly in marginal, cold-limited locales.

We sampled 291 saguaros over thirty populations in Arizona, in the northern portion of their range. Saguaros establish under the south side of their nurse's canopy in the coldest parts of their range more often than expected, while a significant distributional bias is not observed in those in warmer, more moderate plots. To further investigate air temperature as a possible factor in the directional bias of saguaro establishment, we collected microclimate data under the north and south sides of the canopies of two common nurse plants, Cercidium microphyllum (a tree) and Ambrosia deltoidea (a shrub) in Phoenix, Arizona. South sides of nurses have significantly higher minimum temperatures than do the north sides. Survivorship in the coldest areas appears to be greatest under the south side of a nurse's canopy, where warmer wintertime microclimatic conditions occur. We suggest that within-canopy microclimatic variability under a single nurse plant may be reflected in regional distributional and in the survivorship patterns of saguaros throughout Arizona.  相似文献   

Trading in the dark – The medicinal plants production network in Uttarakhand     

Tim Pauls  Martin Franz 《Singapore journal of tropical geography》2013,34(2):229-243

Medicinal plant cultivation and gathering can play a vital role in the course of livelihood diversification for the marginalized population living in remote areas. However, this requires an integration of the respective production networks that allows the producers a fair and reliable income and does not endanger rare plant species. This paper analyses the situation within the Indian state of Uttarakhand, and identifies structures and entities hindering medical plant cultivation and its potentials. Based on the broad network understanding of the Global Production Network approach, the case study focuses on the middlemen and their hidden embeddedness. It shows how governmental organizations and in particular non‐governmental organizations and farmers' institutions can help to overcome clandestine structures of illegal trade and contribute towards a redesign of the medicinal plant network in a more equitable and transparent way.  相似文献   

Ornamental plants and the production of nature(s) in the Spanish real estate boom and bust: the case of Alicante     

María Hernandez  Alfredo Morales 《Urban geography》2013,34(1):71-85

The Spanish real estate boom and bust of the 2000s caused immense economic, social, and environmental changes across the country. Massive urbanization, however, does not necessarily entail the end of nature and natural processes, instead marking a radical transformation of environments and societies. Through a political ecology approach, we analyze how ornamental species have become a fundamental part of new natures induced by urbanization in the Spanish province of Alicante. We connect the economic and ecological characteristics of ornamental plants like the palm tree to urbanization and real estate trends in Alicante. Our evidence indicates that, in Alicante, economic recession and environmental crises (manifested in the pests affecting palm trees) have mutually reinforced one other, creating a new geography of ecological desolation in many areas.  相似文献   

A SIMPLE SOIL MOISTURE INDEX TO FORECAST CROP YIELDS     

Scott A. Isard  Mark R. Welford  Steven E. Hollinger 《自然地理学》2013,34(6):524-538

Neutron probe soil moisture measurements obtained biweekly during the growing season between 1982 and 1991 from multiple depths under grass-covered plots at 17 Illinois Climate Network sites are used to forecast crop yields. A Soil Moisture Index (SMIX) that combines the effect of intensity, duration, and timing of drought or excessively wet conditions was computed by integrating the quantity of available soil moisture throughout the rooting zone over the growing season. Relationships between the SMIX values and crop yields are evaluated at county, regional, and statewide scales. Coefficients of determination (r ²) for relationships between the SMIX values and maize, soybeans, and hay yields at the statewide level are 0.88, 0.74, and 0.81, respectively, when the period of integration is terminated at the end of the growing season. This new soil index can be employed to forecast yields as early as 12 weeks before harvest for the state of Illinois. However, predictions with RMSE ≤ 10% of the mean yield can be achieved only for SMIX integration periods ending 5, 9, and 6 weeks before harvest for maize, soybeans, and hay, respectively. Nomograms are presented for using the relationships between the SMIX values and crop yields to forecast Illinois's major crops well before harvest.  相似文献   

土壤溶解性有机质对植物吸收-输送-贮存重金属的影响研究现状与进展   总被引：1，自引：0，他引：1  

沈亚婷 《岩矿测试》2012,31(4):571-575

土壤溶解性有机质对重金属生物地球化学循环中的生物可利用性起着重要作用。近年来,在土壤溶解性有机质对植物吸收、输送和贮存重金属过程的影响研究领域,国际上主要聚焦于以下三个探索方向:①土壤溶解性有机质与重金属形成配位体,改变重金属在土壤中的迁移性和植物根际环境的作用机理研究;②土壤溶解性有机质可突破植物细胞内重金属吸附点位的限制,通过控制植物细胞壁-重金属复合体的形态及重金属在细胞壁内外的吸收平衡,来干预重金属穿过细胞壁进入植物体的动力学过程研究;③土壤溶解性有机质-重金属的络合形态影响重金属在植物体内的输送和贮存作用过程与机理研究。本文基于研究溶解性有机质和重金属的植物过程中,水体溶解性有机质研究多而土壤溶解性有机质研究少的现状,针对溶解性有机质异质性的研究难点和溶解性有机质与植物亚细胞结构的配位特征的复杂性与局限性,从极性、官能团、配位结构等角度,分析并评述了土壤溶解性有机质和重金属生物地球化学中,植物吸收、输送和贮存重金属过程的研究现状和未来发展趋势。  相似文献