酸沉降类型和喷施方式对木荷和湿地松幼苗生理生态及生长的影响
发布时间：2018-08-20 15:47
【摘要】：酸沉降是目前和将来影响人类福祉的重大环境问题之一,已引起国内外学者的广泛关注。我国南方是继欧美之后的世界第三大酸沉降区,地处长江三角洲的浙江省酸沉降尤为严重。酸沉降威胁着森林生态系统健康,导致林冠稀疏,土壤酸化,甚至造成森林衰退。由于生态系统类型、土壤状况、酸沉降强度、类型和持续时间等不同,酸沉降对森林生态系统的影响存在很大差异。因此,了解大气酸沉降特征及其对亚热带常见树种生理生态和生长的综合影响显得尤为迫切。鉴于此,我们以浙江天童森林生态系统国家野外科学观测研究站为基地,于2010年3月至2011年2月对大气湿性酸沉降进行监测,研究降水酸度和离子组成的动态变化规律。同时,以一年生木荷(Schima superba)和湿地松(Pinus elliottii)幼苗为对象,研究不同酸度(pH 3.5和pH 2.5)、酸沉降类型(SO42-:NO3-分别为8：1和0.7：1)和喷施方式(叶面喷施和土壤灌溉)对幼苗生理生态及生长的影响,并结合土壤化学性质分析,探讨植物对酸沉降的综合响应机理以及导致该森林生态系统衰退的关键因素,以期为酸沉降危害严重地区森林生态系统恢复提供理论依据。研究所取得的主要结果如下：1)天童大气降水酸化程度非常高,雨量加权平均pH值为4.37,酸雨发生率达93.6%。大气降水中阴、阳离子加权平均浓度分别为140.7μeq·L-1和158.9μeq·L-1,具有明显的季节变化规律,冬春季污染显著高于夏秋季。降水中阴离子以S042-和N03-为主,阳离子以NH4+和Ca2+为主,SO42-/NO3-当量比由15年前的4.32—6.42逐渐下降到1.9,说明该地区酸沉降类型由硫酸型向硫酸硝酸复合型转变。海盐对天童大气降水离子组分有一定贡献,但对酸度的影响并不显著。2)重度酸沉降处理(pH 2.5)显著增加土壤全氮含量和交换性酸含量,耗尽土壤交换性盐基离子(特别是钙离子),降低土壤pH值；中度酸沉降处理(pH3.5)下土壤pH值变化不显著,表明土壤对酸沉降有一定的缓冲作用,只有当添加的H+超过了阈值,土壤才发生进一步酸化。短期硫酸型酸沉降处理(SAD)对土壤的酸化作用大于硝酸型酸沉降处理(NAD)。土壤酸化会随着酸沉降的累积而逐渐加剧,土壤终将出现因钙、镁等养分缺失和有毒元素铝的活化而引起的养分失衡状况。3)木荷和湿地松幼苗生理生态和生长对酸度增加的响应不一致。酸沉降对木荷幼苗叶片可见伤害随酸度增加而增大。试验第一年,高强度酸处理通过气孔因素与叶绿素下降等非气孔因素的共同作用,降低木荷叶片光合速率和相对生长速率；次年,酸沉降显著提高木荷叶氮和叶绿素含量,并引起光合速率的小幅增加；但是连续两个生长季的酸沉降处理未引起木荷生物量累积和分配的显著变化。酸处理下湿地松针叶未出现明显受害症状,酸度增加对湿地松光合速率的影响不显著,但增加地上部分生物量分配,进而促进生物量累积。此外,湿地松的快速生长降低了土壤中氮的积累,可缓解酸沉降带来的土壤酸化,因此更能适应酸沉降环境,是南方酸沉降区优质的造林树种。4)幼苗生理和生长对SAD和NAD的响应并不一致。中等强度酸沉降处理下(pH 3.5), NAD对木荷叶片光合作用和生物量累积的抑制效应大于SAD；高强度酸沉降下(pH 2.5), NAD的施肥作用在一定程度上缓解了酸沉降对木荷生理和生长的负效应,并对湿地松侧枝生长和生物量累积产生了更为明显的促进作用。但是,长期过量的氮输入造成的高氮可能会引起植物养分失衡,抵消由于高氮浓度诱导的净光合速率增加的潜力。由以上结果可以发现,由于酸沉降中H6等离子的毒害作用与营养物质施肥效应的不同,决定了植物对不同类型酸沉降响应的差异。5)由于喷施方式的不同,酸沉降通过与植物叶片的直接接触和通过酸化土壤的间接作用对植物生理生态和生长的影响存在差异,且并不同步。叶喷处理对木荷幼苗第一年饱和光合速率的抑制显著大于土壤处理,并引起相对生长速率的下降,说明木荷在短期内受到了直接的酸胁迫伤害；另外,短期土壤喷施(特别是NAD)可显著提高幼苗叶氮和叶绿素含量,进而促进湿地松的生长。然而,酸沉降加剧了土壤酸化,且土壤交换性铝离子和交换性氢离子含量是影响植物生长的主要限制因素。虽然酸沉降通过影响土壤化学性质对林木生长的影响具有一定的时滞性,但其负效应会随着时间延长而逐渐凸显。综合来看,天童大气降水酸化程度非常高,且酸沉降类型逐步由硫酸型向硫酸硝酸复合型转变。林木生长对酸沉降的响应因物种、酸沉降强度、类型和喷施方式的不同而存在很大差异：酸沉降对敏感植物的伤害随酸度增大而加剧；木荷在短期内受到了直接的酸胁迫伤害,但在现有的降水酸度下,长期酸沉降导致的土壤酸化和养分缺失可能是林木生长的主要限制因素；酸沉降的酸化和施肥效应的不同,决定了植物对不同类型酸沉降响应的差异。未来持续酸沉降背景下,特别是酸沉降类型由SAD到NAD的转变,亚热带常绿阔叶林对酸沉降的长期响应值得进一步深入研究。
[Abstract]:Acid deposition is one of the major environmental problems affecting human well-being at present and in the future, which has attracted wide attention of scholars both at home and abroad. South China is the third largest acid deposition area in the world after Europe and the United States, especially in Zhejiang Province, located in the Yangtze River Delta. Acidification may even lead to forest decline. Due to the different types of ecosystem, soil conditions, acid deposition intensity, type and duration, the effects of acid deposition on forest ecosystem are quite different. Therefore, it is urgent to understand the characteristics of Atmospheric Acid Deposition and its comprehensive effects on the physiological ecology and growth of common subtropical tree species. Based on the Tiantong Forest Ecosystem National Field Scientific Observation and Research Station in Zhejiang Province, the atmospheric wet acid deposition was monitored from March 2010 to February 2011 to study the dynamic changes of precipitation acidity and ion composition. The effects of different acidity (pH 3.5 and pH 2.5), acid deposition types (SO42-: NO3-8:1 and 0.7:1, respectively) and spraying methods (foliar spraying and soil irrigation) on seedling physiology, ecology and growth were studied. Combined with the analysis of soil chemical properties, the comprehensive response mechanism of plants to acid deposition and the key factors leading to the decline of forest ecosystem were discussed. The main results are as follows: 1) The acidification degree of Tiantong atmospheric precipitation is very high, the weighted average pH value of precipitation is 4.37, and the incidence of acid rain is 93.6%. The average concentrations of anion and cation weighted in the precipitation are 140.7 mu eq.L-1 and 158.9 mu e, respectively. Q L 1 showed obvious seasonal variation, and the pollution in winter and spring was significantly higher than that in summer and autumn. Atmospheric precipitation ion ion ion ion components contributed to a certain extent, but had no significant effect on acidity. 2) Heavy acid deposition (pH 2.5) significantly increased soil total nitrogen content and exchangeable acid content, depleted exchangeable base ions (especially calcium ions), and decreased soil pH; moderate acid deposition (pH 3.5) did not significantly change soil pH, indicating that soil pH. Soil has a buffer effect on acid deposition, and further acidification occurs only when the added H + exceeds the threshold value. Soil acidification by short-term sulfuric acid deposition (SAD) is greater than that by nitric acid deposition (NAD). Nutrient imbalance caused by the activation of toxic element Al. 3) Physiological ecology and growth of Schima superba and Pinus elliottii seedlings were inconsistent with the increase of acidity. In the following year, acid deposition significantly increased the contents of nitrogen and chlorophyll in Schima superba leaves and caused a slight increase in photosynthetic rate. However, acid deposition did not cause significant changes in biomass accumulation and distribution of Schima superba during the two successive growing seasons. In addition, the rapid growth of Pinus elliottii reduced the accumulation of nitrogen in the soil and alleviated the acidification of the soil caused by acid deposition, so it was more suitable for the acid deposition environment in southern China. 4. The response of seedling physiology and growth to SAD and NAD was not consistent. Under moderate acid deposition (pH 3.5), the inhibition effect of NAD on Photosynthesis and biomass accumulation of Schima superba leaves was greater than that of SAD; under high acid deposition (pH 2.5), NAD fertilization alleviated the physiological effect of acid deposition on Schima superba leaves to some extent. Negative effects on the growth and biomass accumulation of Pinus elliottii lateral branches were more prominent. However, long-term excessive nitrogen input may cause nutrient imbalance and offset the potential for increased net photosynthetic rate induced by high nitrogen concentration. The difference between the toxicity of ions and the effect of nutrient fertilization determines the difference of plant responses to different types of acid deposition. 5) Because of the different spraying methods, the effects of acid deposition on plant physiology, ecology and growth are different and not synchronous through direct contact with plant leaves and indirect action of acidified soil. The inhibition of saturated photosynthetic rate of Schima superba seedlings in the first year was significantly greater than that of soil treatment, and the relative growth rate was decreased, indicating that Schima superba was injured by direct acid stress in a short period of time. In addition, short-term soil spraying (especially NAD) could significantly increase leaf nitrogen and chlorophyll content of seedlings, thereby promoting the growth of Pinus elliottii. Soil acidification is aggravated by acid deposition, and exchangeable aluminum and hydrogen ions are the main limiting factors for plant growth. Although acid deposition has a time lag effect on tree growth by affecting soil chemical properties, its negative effects will gradually become prominent with time. The response of tree growth to acid deposition varies greatly with species, acid deposition intensity, types and spraying methods. The damage of acid deposition to sensitive plants increases with the increase of acidity; Schima superba is subjected to acid deposition in a short period of time. Soil acidification and nutrient deficiency caused by long-term acid deposition may be the main limiting factors for tree growth under the existing precipitation acidity, and the differences in response of plants to different types of acid deposition depend on the acidification and fertilization effects of acid deposition. The long-term response of subtropical evergreen broad-leaved forest to acid deposition deserves further study.
【学位授予单位】：华东师范大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S792.99;S791.246
，
本文编号：2194164
[Abstract]:Acid deposition is one of the major environmental problems affecting human well-being at present and in the future, which has attracted wide attention of scholars both at home and abroad. South China is the third largest acid deposition area in the world after Europe and the United States, especially in Zhejiang Province, located in the Yangtze River Delta. Acidification may even lead to forest decline. Due to the different types of ecosystem, soil conditions, acid deposition intensity, type and duration, the effects of acid deposition on forest ecosystem are quite different. Therefore, it is urgent to understand the characteristics of Atmospheric Acid Deposition and its comprehensive effects on the physiological ecology and growth of common subtropical tree species. Based on the Tiantong Forest Ecosystem National Field Scientific Observation and Research Station in Zhejiang Province, the atmospheric wet acid deposition was monitored from March 2010 to February 2011 to study the dynamic changes of precipitation acidity and ion composition. The effects of different acidity (pH 3.5 and pH 2.5), acid deposition types (SO42-: NO3-8:1 and 0.7:1, respectively) and spraying methods (foliar spraying and soil irrigation) on seedling physiology, ecology and growth were studied. Combined with the analysis of soil chemical properties, the comprehensive response mechanism of plants to acid deposition and the key factors leading to the decline of forest ecosystem were discussed. The main results are as follows: 1) The acidification degree of Tiantong atmospheric precipitation is very high, the weighted average pH value of precipitation is 4.37, and the incidence of acid rain is 93.6%. The average concentrations of anion and cation weighted in the precipitation are 140.7 mu eq.L-1 and 158.9 mu e, respectively. Q L 1 showed obvious seasonal variation, and the pollution in winter and spring was significantly higher than that in summer and autumn. Atmospheric precipitation ion ion ion ion components contributed to a certain extent, but had no significant effect on acidity. 2) Heavy acid deposition (pH 2.5) significantly increased soil total nitrogen content and exchangeable acid content, depleted exchangeable base ions (especially calcium ions), and decreased soil pH; moderate acid deposition (pH 3.5) did not significantly change soil pH, indicating that soil pH. Soil has a buffer effect on acid deposition, and further acidification occurs only when the added H + exceeds the threshold value. Soil acidification by short-term sulfuric acid deposition (SAD) is greater than that by nitric acid deposition (NAD). Nutrient imbalance caused by the activation of toxic element Al. 3) Physiological ecology and growth of Schima superba and Pinus elliottii seedlings were inconsistent with the increase of acidity. In the following year, acid deposition significantly increased the contents of nitrogen and chlorophyll in Schima superba leaves and caused a slight increase in photosynthetic rate. However, acid deposition did not cause significant changes in biomass accumulation and distribution of Schima superba during the two successive growing seasons. In addition, the rapid growth of Pinus elliottii reduced the accumulation of nitrogen in the soil and alleviated the acidification of the soil caused by acid deposition, so it was more suitable for the acid deposition environment in southern China. 4. The response of seedling physiology and growth to SAD and NAD was not consistent. Under moderate acid deposition (pH 3.5), the inhibition effect of NAD on Photosynthesis and biomass accumulation of Schima superba leaves was greater than that of SAD; under high acid deposition (pH 2.5), NAD fertilization alleviated the physiological effect of acid deposition on Schima superba leaves to some extent. Negative effects on the growth and biomass accumulation of Pinus elliottii lateral branches were more prominent. However, long-term excessive nitrogen input may cause nutrient imbalance and offset the potential for increased net photosynthetic rate induced by high nitrogen concentration. The difference between the toxicity of ions and the effect of nutrient fertilization determines the difference of plant responses to different types of acid deposition. 5) Because of the different spraying methods, the effects of acid deposition on plant physiology, ecology and growth are different and not synchronous through direct contact with plant leaves and indirect action of acidified soil. The inhibition of saturated photosynthetic rate of Schima superba seedlings in the first year was significantly greater than that of soil treatment, and the relative growth rate was decreased, indicating that Schima superba was injured by direct acid stress in a short period of time. In addition, short-term soil spraying (especially NAD) could significantly increase leaf nitrogen and chlorophyll content of seedlings, thereby promoting the growth of Pinus elliottii. Soil acidification is aggravated by acid deposition, and exchangeable aluminum and hydrogen ions are the main limiting factors for plant growth. Although acid deposition has a time lag effect on tree growth by affecting soil chemical properties, its negative effects will gradually become prominent with time. The response of tree growth to acid deposition varies greatly with species, acid deposition intensity, types and spraying methods. The damage of acid deposition to sensitive plants increases with the increase of acidity; Schima superba is subjected to acid deposition in a short period of time. Soil acidification and nutrient deficiency caused by long-term acid deposition may be the main limiting factors for tree growth under the existing precipitation acidity, and the differences in response of plants to different types of acid deposition depend on the acidification and fertilization effects of acid deposition. The long-term response of subtropical evergreen broad-leaved forest to acid deposition deserves further study.
【学位授予单位】：华东师范大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S792.99;S791.246
，
本文编号：2194164
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