KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 积雪量变化对荒漠植物凋落物质量损失与养分相对含量的影响 | |
| Alternative Title | The effects of snowfall variation on mass loss and relative nutrient contents of litter decomposition of desert plants |
| 张瑞 | |
| Subtype | 硕士 |
| Thesis Advisor | 张元明 ; 周晓兵 |
| 2019-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 理学硕士 |
| Keyword | 积雪量变化 凋落物分解 养分相对含量 沙漠植物 古尔班通古特沙漠 Snow cover change Litter decomposition Nutrient content Desert plant Gurbantunggut Desert |
| Abstract | 凋落物分解是生态系统中能量流动和养分循环的重要过程， 该过程主要受环境因素和生物因素的影响。冬季积雪可改变地表的水热条件和土壤生物活性，进而影响凋落物的分解。 干旱区荒漠凋落物分解主要受光照的影响， 但冬季积雪是否会显著影响荒漠植物凋落物分解特征，鲜见报道。 本研究以我国最大的固定和半固定沙漠——古尔班通古特沙漠为研究区， 通过设置自然降雪、 加倍增雪和去除降雪实验，研究了冬季地表积雪量变化对荒漠植物凋落物分解的影响。 本研究选择该地区优势种梭梭（Haloxylon ammondendron）和白梭梭（Haloxylon persicum），以及常见种黑沙蒿（Artemisia ordosica）， 粉苞菊（Chondrilla piptocoma） 等 9 种广泛分布的荒漠植物， 模拟 3 种积雪处理（去雪处理、自然条件和加雪处理），采用凋落物分解袋法， 研究了雪被期（2017 年 11 月~2018 年 3 月）和无雪期初期（2018 年 3 月~5 月）荒漠植物凋落物的质量残留和凋落物养分相对含量及其养分比率随分解时间的变化特征， 并分析其影响因素。本研究对因气候变化引起的积雪变化环境下， 预测荒漠生态系统养分循环研究提供一定的数据积累。研究结果表明：（1）凋落物质量残留率和分解率对不同积雪处理的响应因种而异。不同积雪处理显著影响凋落物质量残留率，但对其分解率无显著影响。 9种荒漠植物凋落物中，梭梭凋落物的质量残留率最小（80.19% ~ 92.74%），膜果麻黄凋落物最大（96.21% ~ 98.16%）。 具体表现为：在雪被期， 去雪处理下凋落物质量残留率显著高于其他处理（P＜0.05）；在融雪后无雪被初期， 3 种积雪处理之间凋落物残留率无显著差异。 无论是雪被期还是无雪被期， 3 种积雪处理之间凋落物分解率无显著性差异。（2） 三种积雪处理下不同植物凋落物碳、 氮、 磷相对含量随分解时间呈现出不同的变化趋势， 且受物种差异影响。 凋落物全碳含量随分解时间呈现先增加后下降的趋势，且在雪被期的加雪处理条件下，全碳含量高于其他积雪处理； 凋落物全氮含量表现出整体下降的趋势，且不同植物凋落物全氮含量对不同积雪处理的响应无明显规律； 凋落物全磷含量随分解时间总体呈减少趋势。雪被期的木本植物凋落物在去雪处理下全磷含量显著高于其他处理，而草本植物凋落物在加雪处理下的全磷含量在显著高于其他处理。 在无雪被期，凋落物碳、氮、磷相对含量在三种处理之间无显著差异。（3） 三种积雪处理下，不同植物凋落物木质素和纤维素相对含量变化特征不同。 在木质素方面， 木本植物凋落物总体呈现增加趋势， 草本植物凋落物多为先增加后减少的趋势；在纤维素方面，木本植物和草本植物凋落物表现出一致的规律， 表现为先减少后增加的趋势。（4） 凋落物的分解与凋落物养分含量和养分比率显著相关。 凋落物残留率与凋落物初始养分含量的相关性分析中， 在雪被期， 凋落物质量残留率与凋落物中初始纤维素含量呈显著正相关（P＜0.05），与其他养分含量和养分比率无显著相关性；在实验后期（无雪被期）， 凋落物质量残留率与初始全碳、木质素和纤维素含量呈显著正相关（P＜0.05），与凋落物初始全氮含量呈显著负相关（P＜0.05）。 凋落物质量残留率与凋落物初始碳/氮值和木质素/氮值呈显著正相关（P＜0.05），与氮/磷值呈显著负相关（P＜0.05）。结果发现： 积雪量变化对荒漠植物凋落物的影响主要表现在分解早期冬季雪被期阶段， 积雪覆盖条件促进凋落物分解， 去除地表积雪显著抑制了凋落物分解过程（P＜0.05）。除此之外，地表积雪的存在改变了凋落物在不同分解阶段的分解贡献率。积雪融化后，三种积雪处理之间的凋落物质量损失无显著差异，但凋落物各养分含量和养分比率不同，进而会对下一分解阶段（如夏季光分解阶段）产生影响。研究表明， 荒漠生态系统中凋落物分解的不同阶段主要影响因素不同。凋落物基质质量的影响贯穿整个分解过程， 凋落物在冬季雪被期的分解主要受积雪覆盖的影响（积雪覆盖引起的水分和温度的改变），积雪融化后凋落物的分解可能与微生物分解和光分解相关。 |
| Other Abstract | Environmental and biological factors are two dominant factors to affect litterdecomposition. Snow cover can change the surface hydrothermal conditions anddecomposer activity in winter, which plays important role in litter decomposition. Inthis experiment, litterbags method was used to study the effect of snow cover on litterdecomposition of desert plants in the Gurbantunggut Desert, by simulating changes indepths of snow cover. Nine widely distributed desert plants were selected and threesnow treatments (snow removal, ambient snow and double snow) were conducted inthis area. We measured the change in litter mass residue, decomposition rate and litternutrient content during early snow cover period (November 2017-March 2018) andearly none snow cover period (March 2018-May 2018).The results showed that: The mass residual rate and decomposition rate of litter inthree snow treatments were different along with different species. Haloxylonammodendron had the lowest mass residue rate (80.19% ~ 92.74%) and Ephedraprzewalskii had the highest mass residue rate (96.21% ~ 98.16%). The mass residualrate was significantly higher in snow removal treatment than that in other treatments(P< 0.05). No significant difference in the mass residual rate were found among thethree treatments in the early none snow cover period. In addition, litter decompositionrate did not significantly vary among the three snow treatments during the experimentpeoriod (180 days).It is also showed that The change in contents of carbon (C), nitrogen (N) andphosphorus (P) in litters along with decomposition time in three snow treatmentsdepend on specific species. Total carbon content increased first and then decreased withdecomposition time, and higher content was observed in double snow treatment thanother treatments in early decomposition. Total nitrogen content showed an overalldownward, and the response of nitrogen content was different in three snow treatments.Total phosphorus content decreased with decomposition time. The total phosphoruscontent of woody plant litter in early decomposition stage (snow cover stage) wassignificantly higher than that of other treatments under snow removal treatment, whilethat of herbaceous plant litter under double snow treatment was significantly higherthan that of other treatments. There was no significant difference in the contents of C,N and P between the three treatments at the later stage of decomposition (the early stageof snow-free period).The content of lignin and cellulose in litter of different plants changed differentlyunder three treatments. The lignin content of litter of woody plants showed an overallupward, while that of herbaceous plants increased first and then decreased. The contentof cellulose in plant litter decreased first and then increased.A significantly positive correlation was found between litter mass residue ratesand initial cellulose content in litter at early decomposition (snow cover stage) with nosignificant correlation between litter mass residue rates and other nutrient contents andratios. At the later stage of the experiment, the mass residual rate of litter decompositionwas positively correlated with the initial total carbon, lignin and cellulose content (P<0.05), and negatively correlated with the initial total nitrogen content of litter (P< 0.05).The mass residual rate of litter was positively correlated with the initial C/N andlignin/N of litter (P< 0.05), and negatively correlated with N/P (P< 0.05).In conclusion, the effects of snow treatment on litter was mainly reflected in theearly stage of decomposition in winter. Removal of snow significantly inhibited theprocess of litter decomposition (P< 0.05), and litter decomposition was faster under thecondition of snow cover.In addition, snow cover changed the contribution rate of litterdecomposition at different decomposition stages. After snow melting, no significantdifference was found in litter decomposition among the three snow treatments. We inferthat the driving factors are different in different stages of litter decomposition in desertecosystem. The effect of litter quality runs through the whole decomposition process.The decomposition of litter was mainly affected by snow cover in winter, while thedriving factors after snow melting were related to microbial decomposition andphotolysis. |
| Subject Area | 植物学 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15355 |
| 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 | 张瑞. 积雪量变化对荒漠植物凋落物质量损失与养分相对含量的影响[D]. 北京. 中国科学院大学,2019. |
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