不同封育年限荒漠草原土壤呼吸特征及其影响因子研究

发布时间：2018-01-01 10:24

本文关键词：不同封育年限荒漠草原土壤呼吸特征及其影响因子研究　出处：《宁夏大学》2016年博士论文　论文类型：学位论文

【摘要】：土壤呼吸是大气CO2的重要来源之一,对全球尺度的碳循环调控至关重要。草地生态系统已成为陆地最重要的碳库之一,在全球碳循环中具有重要意义。因此,研究草地生态系统碳循环机制,估算草地生态系统碳储量及草地生态系统在全球变化中的贡献和生态价值具有重要意义。本研究以宁夏不同禁牧封育年限荒漠草原为研究对象,采用动态气室法和数理统计分析相结合的方法,基于2014年～2015年两年野外连续观测禁牧围封11a、7a、放牧不封育(CK)荒漠草原土壤呼吸速率及环境因子的基础上,较为系统的研究了宁夏不同封育年限荒漠草原土壤呼吸速率日、季、年时间动态特征,分析土壤呼吸速率与土壤温、湿度等因子的关系,主要研究结果表明如下：(1)在季节尺度上,TN、AN、AP、SOC、SOCD、URE、ALP均表现为封育未封育,AK、pH、TP、CAT、INV表现为封育未封育；土壤养分、有机碳及酶活性的最大值出现在0～40cm土层。不同封育年限荒漠草原土壤有机碳与土壤全氮、有机质、有机碳密度、土壤过氧化氢酶、脲酶、蔗糖酶、碱性磷酸酶活性呈极显著正相关(P0.01)。土壤酶活性与土壤有机质、有机碳、及其他酶活性呈正显著相关(P0.05)。土壤质量综合指数SQI在2014～2015两个生长季内表现为11a7aCK.(2)在不同时间尺度上,不同封育年限荒漠草原土壤呼吸速率均具有较为明显的单峰曲线变化规律,日最大值出在现在12：00～16：00,最小值出现在00：00～6：00;月最大值出现在8～9月,最小值出现在1月,且均表现为封育未封育,2个生长期土壤呼吸均表现为11a7aCK,土壤呼吸2年均值为11a [0.089 g·(m2·h)-1]7a [0.081 g·(m2·h)-1]CK [0.079 g·(m2·h)-1],年度间表现为20142015。(3)不同时间尺度的不同封育年限荒漠草原5 cm-20 cm土壤剖面CO2浓度具有较为明显的单峰曲线变化规律,剖面CO2浓度随土壤深度的增加而增大。在生长季中土壤剖面CO2浓度呈先增大后减小的趋势,在非生长季中呈先减小后增加的趋势,处理间表现为7a11aCK,年最大值在7月,最小值在1月,年度间表现为20142015。土壤CO2浓度与土壤温度、降雨量呈显著正相关(P0.05)。(4)在不同时间尺度上,封育11a、7a和CK荒漠草原土壤呼吸速率与土壤温度和大气温度的响应均表现为极显著的指数相关(P0.001),且温度敏感性系数Q10均随着土层的加深逐渐变大,0～20 cm土层Q10均值表现为11a7aCK;与空气湿度和土壤含水量在日尺度上呈显著一元二次方程回归(P0.05),与降雨量在不同时间变化尺度上存在极显著一元二次方程回归(P0.01)；与空气CO2浓度、5～20cm土壤剖面CO2浓度呈显著一元二次方程相关(P0.05)。由主成分分析得到,0～20 cm土壤水热条件是影响不同封育年限荒漠草原土壤呼吸不同时间变化的主要因子。(5)不同封育年限荒漠草原地上、地下生物量均呈单峰曲线变化,最大值在8月,处理间表现为11a7aCK。土壤呼吸与地上生物量、地下生物量、地上地下总生物量均呈显著正线性相关(P0.05),与土壤pH值、有机质、有机碳、有机碳密度、过氧化氢酶呈负相关关系(P0.05)。(6)2014～2015年净生态系统生产力NEP表现为11a7aCK,且不同封育年限荒漠草原的NEP0,荒漠草地生态系统表现为碳汇,且封育恢复后草地的净生态系统生产力高于放牧不封育草地。综上所述,禁牧封育措施在一定程度上可以提高荒漠草地土壤有机碳含量和土壤酶活性,有效改善土壤质量综合指数,在退化草地植被恢复和改善土壤养分中具有一定作用。随着封育年的增加,土壤呼吸作用增加,随着土层深度的增加温度敏感性系数逐渐增大,围封禁牧11a、7a对土壤呼吸的作用表现出优于放牧未封育。表层土壤水热状况是荒漠草原的土壤呼吸速率的主要影响因子。总之禁牧封育措施可以有效提高干旱区荒漠草原土壤呼吸作用,荒漠草原生态系统在碳循环中表现为碳汇,对全球气候变化具有一定的重要意义。
[Abstract]:Soil respiration is one of the important sources of atmospheric CO2, is crucial to the global scale carbon cycle regulation. The grassland ecosystem has become one of the most important carbon pool of terrestrial, plays an important role in the global carbon cycle. Therefore, study on the mechanism of carbon cycle in grassland ecosystem, plays an important role in estimating the contribution and ecological value in global change carbon storage and grassland ecosystem grass. This study takes Ningxia different grazing exclosure desert grassland as the research object, by using the method of dynamic chamber method and mathematical statistics analysis, from 2014 to 2015 two years of continuous field observation ungrazed exclosure 11a, based on 7a, no grazing enclosure (CK) of the desert soil respiration rate and environmental factors, the more systematic study of Ningxia fencing desert grassland soil respiration rate, season, year dynamic characteristics, analysis of soil respiration Absorption rate and soil temperature, humidity and other factors of the relationship, the main research results show that as follows: (1) in the season scale, TN, AN, AP, SOC, SOCD, URE, ALP showed no fencing enclosure, AK, pH, TP, CAT, INV showed no fencing fencing the maximum value; soil nutrients, organic carbon and enzyme activity in the soil layer of 0 ~ 40cm. The different fencing desert grassland soil organic carbon and soil total nitrogen, organic matter, organic carbon density, soil catalase, urease, invertase, significantly positive correlation with the activity of alkaline phosphatase (P0.01) activity and soil enzyme. The soil organic matter, organic carbon, and its enzyme activity was positively correlated to him (P0.05). Soil quality index SQI in 2014 to 2015 in two growing seasons in the form of 11a7aCK. (2) at different time scales, different enclosure grassland soil respiration rate of desert life have with single peak curve pattern is more obvious, Japan the maximum value At 12:00 to 16:00 now, the minimum value appeared at 00:00 ~ 6:00; month maximum value appeared in 8~9 months, the minimum value appeared in January, and showed no fencing fencing, 2 growth periods of soil respiration were 11a7aCK, soil respiration 2 years mean 11a [0.089 g (M2 h) -1]7a [0.081 g (M2 - h) -1]CK [0.079 g (M2 h -1]), the annual performance between 20142015. (3) of different time scale of different fencing desert steppe has the single peak curve changes obviously 5 cm-20 cm soil CO2 concentration, CO2 concentration profile with soil depth increase in the growth season increased. Soil CO2 concentration decreased, the increase in the growth of non Ji Zhongcheng decreased trend between the performance of the 7a11aCK, the annual maximum in July and minimum in January, the annual performance between 20142015. soil CO2 concentration and soil temperature, rainfall was significantly Positive correlation (P0.05). (4) in different time scales, enclosure 11a, 7a and CK in response to soil respiration rate and soil temperature in desert steppe and atmospheric temperature showed extremely significant correlation index (P0.001), and the temperature sensitivity coefficient Q10 with soil depth increases gradually from 0 to 20. Cm Q10 11a7aCK represented the mean soil water; a significant quadratic equation with one unknown regression in scale with the air humidity and soil moisture (P0.05), and exist at different time scales of rainfall change significantly quadratic equation with one unknown regression (P0.01); and the air concentration of CO2, 5 ~ 20cm soil profile CO2 the concentration of a significant quadratic equation with one unknown correlation (P0.05). Obtained by principal component analysis, 0 ~ 20 cm soil water and heat condition is the main factor affecting different fencing desert grassland soil respiration in different time. (5) different fencing desert grass in situ, underground biomass were The single peak curve, the maximum value in August, treatments showed 11a7aCK. soil respiration and aboveground biomass, belowground biomass, aboveground total biomass showed a significant positive linear correlation (P0.05), and soil pH value, organic matter, organic carbon, organic carbon density, there was a negative correlation between the catalase (P0.05). (6) from 2014 to 2015 net ecosystem productivity NEP performance for 11a7aCK, and different fencing desert steppe NEP0 desert grassland ecological system for carbon, and after the restoration of net ecosystem productivity of grassland grazing is not higher than that of grassland. In summary, fencing measures can improve grassland soil the organic carbon content and soil enzyme activity in the desert to a certain extent, improve the soil quality index, in the restoration and improvement of soil nutrient in certain degraded grassland vegetation. With the increase of enclosure years, soil respiration increased Plus, with the gradual increase of the soil depth temperature sensitivity coefficient increased, the fenced 11a, the effect of 7a on soil respiration showed better than grazing grazed. Water and heat conditions of surface soil is the main effect of desert steppe soil respiration rate factor. In short enclosure measures can effectively improve arid soil respiration in desert steppe effect of desert steppe ecosystem in the carbon cycle for carbon, has a certain significance to global climate change.

【学位授予单位】：宁夏大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S812.2

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