KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 古尔班通古特沙漠南缘沙垄不同坡位草本植物对极端降水的响应 | |
| Alternative Title | Response of ephemeral plants to extreme precipitation on different slope positions of the sand dune in the Southern Margin of the Gurbantunggut Desert |
| 臧永新 | |
| Subtype | 博士 |
| Thesis Advisor | 马剑英 |
| 2020-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 理学博士 |
| Keyword | 温带荒漠 不同坡位 极端降水 短命植物 Cold desert Different sand dune slope positions Extreme precipitation Ephemeral plants |
| Abstract | 极端降水是生态系统功能改变的主要驱动因素之一，在气候变化的背景下，极端降水发生的频率将不断增加。 极端降水与局部地形相互作用，可能缓冲或加剧极端降水对植被的影响程度。 本研究于古尔班通古特沙漠南缘沙垄四个不同坡位（西坡底、西坡中、东坡中、东坡底）处， 建立了 65%的减雨和收集雨水的装置系统，在连续四年的时间里， 通过开展测量土壤质地、养分、 水分，短命植物草本层片特征、生物量积累和优势物种的物候、功能性性状、 生物量分配模式等工作， 试图了解极端干旱或湿润如何影响古尔班通古特沙漠南缘沙垄不同坡位短命草本层片的组成和生产力， 地形对极端降水的调节程度，以及生态系统恢复到干旱之前功能状态所需的时间。 以期揭示在研究区极端降水发生频率增加的背景下，荒漠短命草本层片的植被动态。 实验结果如下：（1） 坡位对土壤理化性质、温度和土壤含水量的影响。 沙垄不同坡位土壤质地存在显著（P < 0.05） 的差异，表现为西坡和坡底的土壤质地较细腻（粘粒和粉粒含量高），而东坡和坡中的土壤较粗糙（砂粒含量高）。较高的土壤粘粒含量有助于土壤养分的积累，因此， 沙垄坡底的土壤养分（有机碳、 全氮、全磷）含量均显著（P < 0.05） 高于坡中。 沙垄不同坡位土壤含水量在极端干旱处理下存在显著的差异， 表现为东坡的土壤含水量显著（P < 0.05） 高于西坡，此外，东坡土壤含水量对降水的敏感性显著（P < 0.01） 小于西坡。（2） 降水变化对沙垄不同坡位草本层片特征和地上生物量的影响。 减雨或增雨处理均显著（P < 0.01） 改变了草本层片地上生物量，且相对减少量是相对增加量的 1.23 倍。沙垄不同坡位草本层片地上生产力对减雨处理的敏感性存在差异，西坡显著（P < 0.05） 强于东坡。此外， 沙垄不同坡位草本层片对降水处理具有一定稳定性，体现在草本层片优势物种没有改变，其次物种多样性改变不显著。极端干旱使优势物种尖喙牻牛儿苗（Erodium oxyrhinchum） 地上干物质分配到繁殖器官的量显著（P < 0.05） 增加， 而且显著（P < 0.05） 提高了优势物种种子萌发率。（3） 降水变化对沙垄不同坡位优势物种尖喙牻牛儿苗植物功能性状的影响。 降水处理显著（P < 0.05） 改变了沙垄不同坡位优势物种功能性状（株高、比叶面积、 叶片干物质、 叶片氮含量、 叶片磷含量、 叶片 δ13C、 叶片气体交换特征）， 以及叶片 δ13C 与株高、 比叶面积和叶片干物质的含量的关系。（4） 沙垄不同坡位草本层片特征和地上生产力对极端干旱的恢复力。 极端干旱后的第一年，恢复组草本层地上生物量不到对照组草本层片地上生物量的66.0%，极端干旱后的第二年，恢复组草本层地上生物量达到对照组草本层片地上生物量的 79.6%。以上结果表明： 古尔班通古特沙漠南缘沙垄不同坡位草本植物对极端降水响应敏感，体现在地上生物量的显著改变。草本层植物在极端降水（尤其是极端干旱） 处理下，仍然可以保持稳定： 分别体现在物种通过改变自身功能性状使得草本层丰富度和群落组成保持不变；优势物种通过分配更多的干物质到繁殖器官，并且提高后代的萌发率使得自身的优势地位保持不变。 研究区荒漠草本地上生产力对极端降水的变异以负效应为主； 沙垄西坡草本层片地上生产力对减雨处理的敏感性显著强于东坡。此外， 荒漠草本植物对极端干旱具有较强的恢复力。本研究通过探究极端降水对不同坡位短命草本层片特征、生物量积累和优势物种的物候、功能性性状、 生物量分配特征等多方面的影响，深化了对荒漠草本植物-水分关系的认识和理解。 |
| Other Abstract | Extreme climatic conditions are major drivers of ecosystem function anddynaSlopes and their frequency is increasing under climate change. Climatic conditionsinteract with local slope positions, which might either buffer or exacerbate the degreeof climatic stress. Here we sought to understand how extremely dry growing seasonsaffected the composition and productivity of desert ephemeral communities growing insand dunes from the Gurbantunggut desert, and to which extent did slope positionsmodulate the response. We set up a 65% rain reduction and rainwater harvesting systemon four sand dune slope positions (BW: bottom of sand dune of west; MW: middle ofsand dune of west; ME: middle of sand dune of east; BE: bottom of sand dune of east).In the continuous four years, we measured soil moisture, nutrients and texture,ephemeral layer composition, plant phenology, biomass accumulation and biomassallocation patterns for the dominant species, attempt to understand how extremedrought or wetness affects the composition and productivity of ephemeral plants acrossdifferent slope positions in the sand dune of the southern margin of GurbantunggutDesert, the regulation degree of topography to extreme precipitation, and the timerequired for the ecosystem to recover to its functional state before drought. We hope toreveal the vegetation dynaSlopes of ephemeral layer lamelae under the background ofincreasing frequency of extreme precipitation in the study area. The results as follow:(1) Effect of slope positions on soil soil physical and chemical properties, soiltemperature and soil moisture content. There were significant differences (P < 0.05) insoil texture on different sand dune slope positions: the soil texture of the western slopeand the bottom of the slope were relatively fine (high clay and silt content), while thesoil in the eastern slope and the middle of the slope were relatively rough (high sandcontent). The higher soil clay content contributes to the accumulation of soil nutrients.Therefore, the content of soil nutrients (total organic carbon, total nitrogen, total phosphorus) at the bottom of the sand dune was significantly (P < 0.05) higher thanthat in the middle. Under extreme drought treatment, the soil water content on differentsand dune slope positions showed significant differences, which was manifested as thatthe soil water content on the eastern slope was significantly (P < 0.05) higher than thatof the western slope, and the sensitivity of the soil water content of the eastern slope toprecipitation was significantly (P < 0.01) lower than that of the western slope.(2) Effects of precipitation on the characteristics and aboveground biomass (ANPP)of ephemeral layer on different sand dune slope positions.The ANPP of ephemeral layerwas significantly (P < 0.01) changed by both precipitation reduction and precipitationenhancement, and the relative decrease was 1.23 times of the relative increase. Therewas a difference in the sensitivity of the ANPP of ephemeral layer on different sanddune slope positions under the treatment of rainfall reduction, and the western slopewas significantly (P < 0.05) stronger than the eastern slope. We observed plantcommunity richness and composition were not affected, indicating that the compositionof the ephemeral layer in this desert ecosystem may resist under extreme conditions.Additionally, extreme drought increased biomass allocation to reproductive organs andsignificantly (P < 0.05) increased the seed germination rate of the dominant species.(3) Effects of precipitation on the functional traits of the dominant species ondifferent sand dune slope positions.The precipitation treatment significantly (P < 0.05)changedthe functional traits (height, SLA: specific leaf area, LDMC: leaf dry mattercontent; LNC:leaf nitrogen content; LPC: leaf phosphorus content; leaf δ13C;characteristics of gas exchange ) of dominant species in different slope positions of thesand dune and the relationship between leaf δ13C and height, SLA、 LNMC).(4) The resilience of ephemeral layer characteristics and the ANPP to extremedrought on different sand dune slope positions. The first year after extreme drought, theANPP of the drought recovery group was less than 66.0% of that of the control group;the second year after extreme drought, the ANPP of the drought recovery group was79.6% of that of the control group.The above results show that the ephemeral layer in different slopes of sand dunewere sensitive to the extreme precipitation, which was reflected in the significantchange of the ANPP. At the same time, under the treatment of extreme precipitation(especially extreme drought), the ephemeral layer plants could still remain stable, whichwas reflected that the species could change their functional traits to make the ephemerallayer richness and community composition remain unchanged; dominant speciesmaintained their dominance by allocating more dry matter to their reproductive organsand increasing the germination rate of their offspring. The variation of productivity ofdesert herbaceous overland to extreme precipitation in the study area was mainlynegative; the western slope was significantly stronger than the eastern slope. In addition,desert herbs have a strong resilience to extreme droughtThis study deepened the understanding of desert ephemeral layer plant-waterrelationship by exploring the influence of extreme precipitation on the ephemeral layercomposition, plant phenology, biomass accumulation and biomass allocation patternsfor the dominant species on different sand dune slope positions. |
| Subject Area | 生态学 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15470 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 臧永新. 古尔班通古特沙漠南缘沙垄不同坡位草本植物对极端降水的响应[D]. 北京. 中国科学院大学,2020. |
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