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| C3植物红砂和C4植物珍珠混生光合生理特征及种间相互作用研究 | |
| 其他题名 | Studies on Photosynthetic Characteristics and Interspecific Interactions of C3 Plant Reaumuria Soongorica and C4 |
| 严巧娣 | |
| 出版年 | 2010 |
| 学位类型 | 博士 |
| 导师 | 苏培玺 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | C3和C4植物混生在草地生态系统中较多，但在荒漠生态系统并不多，特别是木本植物（包括半木本植物）混生群落更不多见。而荒漠地区C3与C4植物自然混生群落，特别是木本C3与C4混生群落，是珍贵的植物联合生长类型，对它们适应环境的光合生理特性变化以及种间相互作用的研究具有重要意义。\n \n在我国河西走廊中部砂砾质戈壁荒漠地区，超旱生C3小灌木红砂（Reaumuria soongorica Maxim.）和C4半灌木珍珠（Salsola passerina Bunge）混生在一起，以独特方式——单生（各自单独生长）和联生（2种植物紧密结合在一起生长）——适应高温强光和干旱的严酷环境。本研究通过连续有降水量差异的三年样方调查，结合光合生理特征参数测量，包括气体交换参数以及叶绿素荧光参数，研究不同光合途径的荒漠植物红砂和珍珠在混生群落中不同生存方式下的光合生理特性及其在不同水分条件下的表现；通过种间相互作用指标，以及移除实验后红砂珍珠的光合生理特征参数，进行两者种间关系的初步研究，以探讨C3和C4植物对环境梯度的不同响应，C3和C4荒漠植物适应环境的机理差异，以及C3和C4荒漠植物种间相互作用的方式。\n \n结果表明，红砂和珍珠为优势种的混生群落总盖度及分盖度随年降水量的增加而增大，且两者平均地上生物量和总生物量也随降水量的增加而增大。\n \n混生群落中，两种光合途径荒漠植物对干旱戈壁荒漠极端环境的响应既有相似点又有不同点。相似点：C3植物红砂和C4植物珍珠的净光合速率（Pn）日变化曲线基本均呈双峰型；不同水分条件下，红砂与珍珠的水分利用效率（WUE）日均值均为极端干旱条件（EA）＞7月下旬干旱条件（GA1）＞雨后土壤湿润条件（MS）＞雨后空气湿润条件（MA）＞8月下旬干旱条件（GA2）。不同点：不同水分条件下，红砂的Pn、E、Gs和Fv/Fm日均值均高于珍珠，而珍珠的WUE日均值却高于红砂。表明两种植物在相同的生境下对长期气候和土壤干旱采取了不同的生存策略：C3植物红砂通过维持较高净光合速率、较高蒸腾速率和低水分利用效率来生存，属于避旱型；而C4植物珍珠则通过高水分利用效率来更好的生存于水资源不太丰富的荒漠，属于耐旱型。\n \n在混生群落中，联生红砂的Pn和Fv/Fm日均值均高于单生红砂，而联生珍珠的Pn和Fv/Fm日均值均低于单生珍珠，即红砂与珍珠联生后能提高红砂的光合能力；而不论是红砂还是珍珠，联生方式下的地上地下生物量之比都小于单生，即联生后两者均能更多地增加地下部分发展的比率，提高水分获取能力。这表明两者间存在一定的正相互作用，并且以联生后C4植物珍珠对C3植物红砂的促进作用为主。由混生群落中红砂和珍珠的相对总生物量（RYT）以及邻体相对作用指数（RNE）随年降水量的变化证明，联生红砂和珍珠间的正相互作用一定程度上符合胁迫梯度假说。\n \n移除实验表明，移除后保留红砂或珍珠的Pn、Fv/Fm及WUE都比联生和单生时的有所提高，而E则有所降低，说明剔除地上部分，地下部分的正相互作用更大。\n根据以上研究结果得出，不同植物对干旱戈壁荒漠严酷环境的响应策略不同，植物间的特殊生存方式——联生，可能会缓解或减轻极端环境的不利影响，从而促进植物生长发育。 |
| 英文摘要 | The mixed community of C3 and C4 plants is easily seen in grassland ecosystem, but hardly seen in desert ecosystem, especially mixed communities of woody plants are rarer. In the desert region of China, some C3 and C4 shrubs coexisted in particular manners under some specific habitat and adapted to the extreme arid environment, which is associated with high temperature and intensive radiation. \n \nThe mixed communities of C3 semishrub Reaumuria soongorica and C4 subshrub Salsola passerina of the Heihe River Basin in Hexi Corridor were investigated. It could be found that there were R. soongorica and S. passerina isolated-growing respectively, and also there were R. soongorica and S. passerina closely growing together forming so-called inter-growing manner. The naturally mixed communities of R. soongorica and S. passerina, which is the common phenomenon with certain peculiarities, are the best materials to research the responses of C3 and C4 plants to severe environments in the same habitats and interspecific interactions. The ecological investigation of the mixed community was conducted through consecutive three years that were different in annual precipitation, combined with measurements of photo-physiological characteristics, including gas exchange parameters and chlorophyll fluorescence parameters for the two coexisting C3 (R. soongorica) and C4 (S. passerina) woody species growing in different growing manners under different waer conditions in the Gobi desert of northwestern China. Through the indexes of interspecfic interaction and photo-physiological characteristics of R. soongorica and S. passerina after the removal experiment, the preliminary interactions between the two plants was studied. The study could further provide an important theoretical basis and application information to reveal the adaptive strategies of C3 and C4 desert plants to arid environments in the background of global climate change and explore the role of C3 and C4 plants in the desert ecosystem.\n \nThe results showed that, total coverage of the mixed community and the coverage of dominant plant species increased with the increase of annual precipitation; and the average of aboveground, underground and the total biomass of both R. soongorica and S. passerina also increase with the increase of precipitation. \n \nIn the mixed community, there are both similarities and differences between the two desert plants with different photosynthetic pathways responding to severe desert environment. Similar point: the diurnal curve of net photosynthetic rate (Pn) for C3 plant R. soongorica and C4 plant S. passerina were almost bimodal. Under different water conditions, the average daily value of water use efficiency (WUE) for both the two plants were: extremely arid condition (EA) > generally arid condition in late July (GA1) > moist soil condition during post-rain (MS) > moist atmospheric condition during post-rain (MA) > generally arid condition in late August (GA2). Differences are as following: whether isolated-growing or inter-growing, Pn, E, Gs and Fv/Fmof R. soongorica were all higher than S. passerina, while WUE of S. passerina was higher than R. soongorica. It shows that, R. soongorica and S. passerina take different strategies for survival when suffering water scarcity in the same desert habitats: R. soongorica use the means of maintaining a higher net photosynthetic rate and a higher transpiration rate to survive; while S. passerina survive here through the higher water use efficiency.\n \nCompared the same species growing in different manners, it can be found that, when inter-growing, the Pn and Fv/Fm of R. soongorica were both higher than isolated-growing ones, while the Pn and Fv/Fm of isolated-growing S. passerina were lower than inter-growing ones. That is, when inter-growing, the C4 desert plants S. passerina could facilitate the C3 desert plants. \n \nThe above and below ground biomass ratio of both R. soongorica and S. passerina in inter-growing manner were less than isolated ones, showing that when inter-growing, both the two plants could increase the underground part development ratio to improve ability of obtaining water, which may show some positive interaction. The changes of positive interactions between inter-growing C3 plants R. soongorica and C4 plants S. passerina was some extent consistent with “Stress gradient hypothesis”. \n \nAfter neighbor removal treatment, Pn, Fv/Fm and WUE of R. soongorica and S. passerina with removing neighbour vegetation were higher than those of inter-growing ones and isolated-growing ones, while E decreased. It indicated that, the absence of the aerial part for the competition, make the positive interaction of belowground between the two plants is greater.\n \nBased on the above findings, it can be concluded that different plants adapt to the harsh desert environment with different drought-response strategies. Plants coexisting in particular manners—inter-growing manner, may alleviate or mitigate the adverse effects of extreme environments, thus promoting plant growth and development. |
| 中文关键词 | 红砂 ; 珍珠 ; 单生 ; 联生 ; 种间正相互作用 |
| 英文关键词 | Reaumuria soongorica Salsola passerina isolated-growing inter-growing interspecific positive interaction |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286847 |
| 推荐引用方式 GB/T 7714 | 严巧娣. C3植物红砂和C4植物珍珠混生光合生理特征及种间相互作用研究[D]. 中国科学院大学,2010. |
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