大渡河中游干旱河谷区云南松人工林凋落叶分解和土壤呼吸对增加降水的响应

发布时间：2018-06-16 01:46

本文选题：增加降水 + 云南松人工林　；参考：《四川农业大学》2016年博士论文

【摘要】：由于全球气候的变暖,引起全球降水格局发生了异常变化。其中,降水量大幅增加是降水格局异常变化的一种体现。近几十年来降水增加发生的频率、范围和持续时间都有所增加。森林生态系统是最大的陆地生态系统,土壤碳、氮、水循环过程是森林生态系统中最重要的三种循环过程。降水量的增加通过改变土壤环境因素,进而影响凋落物分解、土壤碳氮、土壤呼吸、土壤有机碳矿化等关键生态过程,势必会对森林生态系统过程造成重大影响。四川省石棉县地处大渡河中游干旱河谷区,全年干、湿季节分明,从上世纪50至70年代和90年代至今,该地区降水量呈上升趋势,尤其2000年初期降水量明显增加,比上世纪90年代降水量增加了48%。云南松(Pinus yunnanensis)是该区域主要的造林树种。本研究于2013年6月至2015年5月,对大渡河中游干旱河谷区石棉县云南松人工林进行增加降水试验,试验设置对照(CK,0 mm·m-2·a-1)、增水10%(A1,80 mm·m-2·a-1)、增水20%(A2,160 mm·m-2·a-1)和增水30%(A3,240 mm.m-2.a-1)4个处理水平。在研究了增加降水对云南松人工林凋落叶分解、土壤碳氮、土壤呼吸和土壤有机碳矿化影响的基础上,初步探讨了云南松人工林土壤碳氮水关系对增加降水的响应。研究主要结果如下：(1)云南松人工林凋落叶分解、土壤呼吸和土壤有机碳矿化及其相关因素均具有不同的季节特征。凋落叶分解、土壤呼吸和土壤有机碳矿化具有湿季快、干季慢的季节特征；土壤温度、土壤湿度、土壤全氮、SMBC和SMBN具有湿季高、干季低的季节特征,土壤硝态氮和铵态氮则具有湿季低、干季高的季节特征；但STOC没有明显的季节特征。(2)增加降水促进了云南松人工林凋落叶分解,促进作用大小表现为A1A2A3。增加降水也促进了凋落叶木质素降解,促进作用大小表现为A3A2A1；A1处理促进了的纤维素降解,A2和A3抑制了纤维素降解。凋落叶各养分元素释放模式没有受降水量增加的影响。增加降水促进了凋落叶C、N、P和K元素的释放,A1处理促进了Ca和Mg元素的释放,A2和A3处理抑制了Ca和Mg元素的释放。凋落叶C/N、C/P和木质素/N随分解时间增加而升高,增加降水提高了凋落叶C/N和C/P,而木质素/N在A1处理下降低,在A2和A3处理下提高。(3)增加降水提高了云南松人工林STOC含量,但这种作用不随增水量的增加而增大；土壤全氮、硝态氮和铵态氮含量均随降水量的增加而降低。在湿季,A1处理提高了SMBC含量,对SMBN含量无显著影响,A2处理提高了SMBC和SMBN含量,A3处理降低了SMBC和SMBN含量；在干季, SMBN含量随降水量的增加而降低,仅A3处理降低了SMBC含量。(4)增加降水提高了云南松人工林土壤有机碳矿化,但这种作用不随降水量的增加而增大。相关分析表明,土壤有机碳矿化与STOC之间没有明显的关系,与SMBC之间有明显的相关关系。增加降水没有改变土壤有机碳矿化与STOC的关系,而A2和A3处理则降低了土壤有机碳矿化与SMBC的关系。(5)在降水量增加下,A1处理对土壤呼吸和土壤碳排放量没有明显影响,A2处理促进了土壤呼吸并增加了土壤碳排放量,A3处理抑制了土壤呼吸并降低了土壤碳排放量。湿季期间增加降水未对土壤温度和湿度造成显著影响,干季期间增加降水提高了土壤湿度,而土壤温度未受到影响。土壤呼吸与土壤温度具有极显著正指数关系,增加降水没有明显影响两者关系；各处理土壤呼吸的温度敏感性(Q1o值)分别为2.13(CK)、2.11(A1)、2.11(A2)和2.53(A3),其中A3处理的Qlo值较CK明显升高∽0.05)。土壤呼吸与土壤湿度具有极显著二项式关系,而在降低温度的影响后,两者之间没有显著相关性关系,增加降水也没有明显改变它们的关系；与土壤温度相比,土壤湿度对土壤呼吸的影响相对较小。土壤呼吸与土壤温度、土壤湿度具有极显著二元线性关系,变异解释量较单因素有明显提高,增加降水降低了土壤温度和土壤湿度对土壤呼吸的综合影响。土壤呼吸与SMBC、SMBN之间有明显的相关关系,A1和A2处理提高了SMBC与土壤呼吸的关系,A3处理降低了两者的关系；仅A1处理提高了SMBN与土壤呼吸的关系。(6)云南松人工林土壤碳水关系中,土壤水分与土壤呼吸之间有明显的相关关系,增加降水没有影响土壤碳水关系。土壤氮水关系中,土壤水分与土壤硝态氮、土壤铵态氮、SMBN之间有明显的相关关系。在降水量增加下,A1和A2处理降低了土壤水分与土壤铵态氮的关系,A1和A3处理降低了土壤水分与SMBN的关系。土壤碳氮关系中,土壤有机碳与土壤氮之间没有明显的相关关系,增加降水也没有影响它们的关系。SMBC与土壤全氮、土壤硝态氮、土壤铵态氮之间存在明显的相关关系；增加降水降低了SMBC与土壤全氮的关系,A2和A3处理降低了SMBC与土壤硝态氮的关系,A1和A2处理提高了SMBC与土壤铵态氮、SMBN的关系,而A3处理仅降低了SMBC与土壤铵态氮的关系。土壤呼吸与土壤氮之间有明显的相关关系,增加降水降低了土壤呼吸与土壤全氮、土壤硝态氮的关系；A3处理降低了土壤呼吸与土壤铵态氮的关系；而A1处理提高了土壤呼吸与SMBN的关系。土壤有机碳矿化与土壤氮之间存在明显的关系,总体上增加降水降低了它们的关系。土壤碳氮水关系中,土壤水分总体与土壤碳氮比之间没有明显的相关关系,增加降水也没有改变它们之间的关系。仅土壤水分与土壤呼吸/全氮、土壤有机碳矿化/SMBN之间存在明显的相关关系,增加降水降低了它们的关系。土壤水分与SMBC/SMBN之间虽没有明显的相关关系,但A2处理提高了两者的相关性。综上,土壤碳氮水关系对增加降水的响应较为复杂,要深入揭示增加降水对土壤碳氮水关系的影响仍需进一步研究。
[Abstract]:Global climate warming has caused abnormal changes in the global precipitation pattern. Among them, a significant increase in precipitation is an embodiment of abnormal changes in precipitation patterns. The frequency, range and duration of precipitation increase in recent decades have increased. Forest ecosystems are the largest terrestrial ecosystems, soil carbon, nitrogen, and water circulation. The process is the three most important cycle process in the forest ecosystem. The increase of precipitation is bound to affect the process of litter decomposition, soil carbon and nitrogen, soil respiration, soil organic carbon mineralization and other key ecological processes by changing the soil environmental factors. It is bound to have a significant impact on the process of forest ecosystem. Sichuan Shimian County is located in the Dadu River. In the arid valley area, the dry season is clear throughout the year. From 50 to 70s and 90s of the last century, the precipitation in this area has been increasing, especially in the early 2000, the precipitation increased obviously, and the precipitation in Yunnan (Pinus yunnanensis) is the main tree species in this region compared with the precipitation in 90s of the last century. This study is from June 2013 to 2015. In May, Yunnan pine plantation of Yunnan pine plantation in Shimian County, the middle reaches of Dadu River, was tested. The experiment was set up as control (CK, 0 mm. M-2. A-1), water increase 10% (A1,80 mm. M-2. A-1), water increase 20% (A2160 mm. M-2 A-1) and 30% water increase. The precipitation was studied to decompose the litter decomposition of the pine plantation in Yunnan. On the basis of the influence of soil carbon and nitrogen, soil respiration and soil organic carbon mineralization, the response of soil carbon and nitrogen water relationship in Yunnan pine plantation soil to increasing precipitation was preliminarily discussed. The main results were as follows: (1) the litter decomposition of Yunnan pine plantation, soil respiration and soil organic carbon mineralization and related factors have different seasonal characteristics. Litter decomposition, soil respiration and soil organic carbon mineralization have the seasonal characteristics of fast wet season and slow dry season; soil temperature, soil moisture, soil total nitrogen, SMBC and SMBN have wet season high, dry season low seasonal characteristics, soil nitrate nitrogen and ammonium nitrogen have the seasonal characteristics of low wet season and dry season; but STOC has no obvious seasonal characteristics. (2) Increasing precipitation promoted the decomposition of leaf litter in Yunnan pine plantation, which promoted the effect of increasing precipitation as A1A2A3. increased precipitation and promoted the degradation of lignin in litterleaf leaves. The promotion effect was A3A2A1, A1 treatment promoted cellulose degradation, A2 and A3 inhibited cellulose degradation. The release patterns of nutrient elements in litters were not increased by precipitation. Increasing precipitation promotes the release of C, N, P and K elements in leaves of litters. A1 treatment promotes the release of Ca and Mg elements. A2 and A3 treatment inhibits the release of Ca and Mg elements. (3) increasing precipitation increased the STOC content of Yunnan pine plantation, but this effect did not increase with the increase of water content; the total nitrogen, nitrate nitrogen and ammonium nitrogen in soil decreased with the increase of precipitation. In wet season, A1 treatment improved the content of SMBC and had no significant effect on the content of SMBN, A2 treatment improved the content of SMBC and SMBN, A3 The content of SMBC and SMBN decreased, and the content of SMBN decreased with the increase of precipitation in dry season. Only A3 treatment reduced SMBC content. (4) increasing precipitation increased soil organic carbon mineralization in Yunnan pine plantation, but this effect did not increase with the increase of precipitation. Correlation analysis showed that there was no obvious mineralization between soil organic carbon and STOC. There was a significant relationship with SMBC. Increasing precipitation did not change the relationship between soil organic carbon mineralization and STOC, while A2 and A3 treatments reduced the relationship between soil organic carbon mineralization and SMBC. (5) under the increase of precipitation, A1 treatment had no significant influence on soil respiration and soil carbon emissions, and A2 treatment promoted soil respiration and increased soil respiration. Soil carbon emissions, A3 treatment inhibited soil respiration and reduced soil carbon emissions. During the wet season, increasing precipitation did not affect soil temperature and humidity significantly. During the dry season, increasing precipitation increased soil moisture, while soil temperature was not affected. Soil respiration and soil temperature had a very significant positive exponential relationship with soil soil temperature, and increased precipitation. The temperature sensitivity (Q1o) of soil respiration (Q1o) was 2.13 (CK), 2.11 (A1), 2.11 (A2) and 2.53 (A3), respectively. The Qlo value of A3 treatment was significantly higher than that of CK. Soil respiration and soil moisture had a significant binomial relationship with soil moisture, but there was no significant correlation between them after reducing the effect of temperature. The relationship between soil moisture and soil temperature has little effect on soil respiration. Soil respiration and soil temperature and soil humidity have a very significant two yuan linear relationship, and the variation of soil moisture is significantly higher than that of single factor, and the increase of precipitation reduces soil temperature and soil humidity. There was a significant correlation between soil respiration and SMBC and SMBN. A1 and A2 treatment improved the relationship between SMBC and soil respiration, A3 treatment reduced the relationship between the two. Only A1 treatment improved the relationship between SMBN and soil respiration. (6) there was a relationship between soil water and soil respiration in the soil water relationship of Yunnan pine plantation soil. In the relationship of soil nitrogen and water, there was a significant correlation between soil moisture and soil nitrate nitrogen, soil ammonium nitrogen and SMBN. Under the increase of precipitation, A1 and A2 treatment reduced the relationship between soil moisture and soil ammonium nitrogen, A1 and A3 treatment reduced soil moisture and SMBN. In the relationship between soil carbon and nitrogen, there is no significant correlation between soil organic carbon and soil nitrogen, and increasing precipitation does not affect the relationship between.SMBC and soil total nitrogen, soil nitrate nitrogen and soil ammonium nitrogen; increasing precipitation reduces the relationship between SMBC and total nitrogen in soil, A2 and A3 treatment reduce SMBC and SMBC The relationship between soil nitrate nitrogen, A1 and A2 treatment increased the relationship between SMBC and soil ammonium nitrogen and SMBN, while A3 treatment only reduced the relationship between SMBC and soil ammonium nitrogen. There was a significant correlation between soil respiration and soil nitrogen, and increased precipitation decreased the relationship between soil respiration and soil total nitrogen and soil nitrate nitrogen; A3 treatment reduced soil respiration. The relationship between soil ammonium nitrogen and soil nitrogen, and A1 treatment improved the relationship between soil respiration and SMBN. There was a significant relationship between soil organic carbon mineralization and soil nitrogen. In general, increasing precipitation reduced their relationship. In the relationship between soil carbon and nitrogen water, there was no significant correlation between soil moisture and soil carbon and nitrogen ratio, and no precipitation increased. There is a significant correlation between soil moisture and soil respiration / total nitrogen, soil organic carbon mineralization, /SMBN, and the relationship between soil moisture and SMBC/SMBN. Although there is no significant correlation between soil moisture and SMBC/SMBN, A2 treatment improves the correlation between the two. The response of increasing precipitation is more complicated. It is still necessary to further reveal the effect of increasing precipitation on soil carbon, nitrogen and water.
【学位授予单位】：四川农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S714

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