寧南山區(qū)典型植物莖葉分解過程及其對(duì)土壤養(yǎng)分和微生物群落的影響
發(fā)布時(shí)間：2018-09-03 17:49
【摘要】：國(guó)家實(shí)施退耕還林還草政策以來,黃土高原植被恢復(fù)略見成效,地上枯落的植物莖葉有了大量的積累。植物莖葉的累積和分解可以改變土壤微環(huán)境,提高土壤養(yǎng)分含量,增加土壤微生物多樣性。作為連接土壤和植被的紐帶,植物莖葉在生態(tài)系統(tǒng)物質(zhì)和能量的循環(huán)中具有重要的作用。本研究選取該區(qū)三種典型草本植被作為研究對(duì)象,采用野外分解袋法模擬植物莖葉的分解,對(duì)植物莖葉分解過程中自身養(yǎng)分變化以及土壤養(yǎng)分和土壤微生物多樣性變化進(jìn)行分析,研究不同植被及處理對(duì)土壤性質(zhì)的影響特征,為黃土高原植被恢復(fù)和生態(tài)系統(tǒng)生物多樣性恢復(fù)提供基礎(chǔ)科學(xué)依據(jù),主要結(jié)論如下:(1)植物莖葉營(yíng)養(yǎng)元素的釋放規(guī)律受季節(jié)性變化明顯,不同處理元素的釋放規(guī)律差異不顯著。植物莖葉中元素的初始含量直接影響其分解速率,BLX的初始氮含量最低,初始木質(zhì)素和纖維素含量均最高,導(dǎo)致BLX和含有BLX組合的處理莖葉分解速率較低,且含有BLX的處理在分解末期養(yǎng)分損失量均較低。各組合處理的初始氮含量較高,所以在分解過程中氮元素基本處于釋放狀態(tài)。各處理有機(jī)碳在分解過程中均出現(xiàn)淋溶、富集、釋放的模式,分解前期易溶性物質(zhì)和易分解碳水化合物的淋失和降解使得有機(jī)碳迅速釋放,分解后期木質(zhì)素、纖維素等難溶物質(zhì)比例增大,使得分解變得緩慢。隨著分解時(shí)間的進(jìn)行,不同處理磷元素的釋放規(guī)律基本一致,基本遵循釋放、富集、釋放的波動(dòng)模式。各組合處理和單種植物處理間磷素富集的起始時(shí)間不同,單種植物處理中CMC和BLX在分解釋放45天后便開始緩慢富集,而各組合處理和TGH在分解釋放90天后才開始富集。到分解390天為止,各處理植物莖葉木質(zhì)素分解不明顯,纖維素在分解前90天無明顯變化,之后分解迅速,CMC莖葉的分解速率最快且分解量也最大。(2)添加植物處理的土壤養(yǎng)分的變化趨勢(shì)和空白土壤的變化趨勢(shì)基本一致,說明植物莖葉分解對(duì)土壤養(yǎng)分的影響主要受外界水熱條件變化的影響。添加植物處理的土壤養(yǎng)分相對(duì)于空白土壤養(yǎng)分都有所增加,說明植物莖葉的分解可以為土壤提供一定的營(yíng)養(yǎng)物質(zhì)。各個(gè)處理間土壤養(yǎng)分的變化差異不顯著,這和植物莖葉自身的化學(xué)組成有密切的關(guān)系。土壤全氮主要來源于植物莖葉分解所形成的有機(jī)物質(zhì),因此土壤全氮和有機(jī)碳具有相似的變化趨勢(shì),土壤全氮和有機(jī)碳含量均在分解135天后才達(dá)到最高值。土壤速效磷含量受水熱條件變化明顯,在夏季雨水充足情況下土壤速效磷含量開始緩慢增加。植物莖葉分解初期土壤銨態(tài)氮含量有所減少,硝態(tài)氮含量有所增加,整個(gè)分解過程土壤銨態(tài)氮含量變化不明顯,植物莖葉的分解對(duì)土壤速效氮的影響主要表現(xiàn)為硝態(tài)氮含量的變化。(3)土壤酶活性受外界環(huán)境因素的影響較大,受植物莖葉分解的影響較小。土壤的初始養(yǎng)分狀況會(huì)在一定程度上影響土壤酶活性,土壤有機(jī)碳、全氮、速效氮等對(duì)土壤脲酶、蔗糖酶、纖維素酶、堿性磷酸酶活性有顯著影響,土壤速效磷含量與土壤堿性磷酸酶活性呈顯著負(fù)相關(guān)關(guān)系。植物莖葉的分解能提高土壤的養(yǎng)分狀況,改善土壤環(huán)境,植物莖葉分解末期,土壤脲酶、蔗糖酶、纖維素酶活性均有所增加,而土壤堿性磷酸酶活性有所減少,這可能與堿性磷酸酶礦化土壤磷素使無機(jī)磷增加有關(guān)。植物莖葉混合分解能更好的提高土壤中酶的活性,改善土壤養(yǎng)分狀況,但各處理土壤酶活性的增加和減少差異均不顯著。(4)土壤微生物生物量受外界環(huán)境條件的影響較大,而土壤和植物莖葉的初始養(yǎng)分含量及其化學(xué)計(jì)量比是導(dǎo)致各處理土壤m(xù)bn和mbc含量產(chǎn)生差異的主要原因。外界水熱條件充足時(shí),適宜微生物生長(zhǎng)繁殖,微生物數(shù)量的增加提高了土壤微生物生物質(zhì)量;分解試驗(yàn)結(jié)束時(shí)土壤m(xù)bn和mbc與植物莖葉和土壤初始養(yǎng)分含量進(jìn)行相關(guān)性分析,結(jié)果顯示植物莖葉分解試驗(yàn)結(jié)束時(shí)土壤m(xù)bc和mbn含量與土壤和植物莖葉初始全氮、全磷、木質(zhì)素含量在0.01水平下均呈正相關(guān)關(guān)系,其中土壤m(xù)bn含量與土壤初始全氮含量呈顯著正相關(guān)關(guān)系,相關(guān)系數(shù)達(dá)0.909(p0.01)。分解前期,植物莖葉中易分解有機(jī)物質(zhì)的釋放補(bǔ)充了土壤中營(yíng)養(yǎng)元素含量,加快了土壤微生物的新陳代謝。微生物利用充足的碳源進(jìn)行自身生長(zhǎng)繁殖,同時(shí)將枯落物碳同化為生物體碳,導(dǎo)致土壤m(xù)bc的增加。隨著植物莖葉分解的進(jìn)行,纖維素、木質(zhì)素等難分解物質(zhì)的積累使后期分解速率越來越慢,土壤對(duì)微生物的供給不及時(shí),土壤m(xù)bc含量就開始降低。同樣,植物莖葉的分解和養(yǎng)分的釋放加速了土壤的礦化作用,微生物的大量繁殖導(dǎo)致土壤m(xù)bn增加,隨著植物莖葉分解的進(jìn)行,土壤中氮素的大量消耗不能滿足微生物的生長(zhǎng)繁殖,導(dǎo)致土壤m(xù)bn的下降。植物莖葉分解后期,各組合處理土壤微生物生物量略高于單種植物處理,但差異不明顯,各組合間土壤微生物生物量差異不顯著,單種植物間土壤微生物生物量差異也不顯著。植物莖葉分解末期,各添加植物樣品的處理土壤m(xù)bn和土壤m(xù)bc含量均略低于空白處理土壤。(5)利用高通量測(cè)序技術(shù)對(duì)不同處理下植物莖葉分解435天后的土壤微生物特征研究發(fā)現(xiàn):添加植物莖葉的處理土壤細(xì)菌和真菌的ace指數(shù)和chao指數(shù)均高于空白處理,simpson指數(shù)小于空白處理,shannon指數(shù)大于空白處理,且在0.05水平下差異顯著,說明植物莖葉的分解能顯著提高土壤細(xì)菌和真菌的豐度,增加土壤細(xì)菌的多樣性。在不同的分類水平下,土壤細(xì)菌的種類以放線菌、變形菌、綠灣菌門、芽單胞菌為主,這幾種細(xì)菌的相對(duì)豐度占土壤中所有細(xì)菌的90%以上,其中放線菌門的相對(duì)豐度占40%左右。在門水平下,土壤真菌的種類主要包括:子囊菌門(ascomycota)、擔(dān)子菌門(basidiomycota)、球囊菌門(glomeromycota)等,這三種門類真菌的相對(duì)豐度占土壤中所有真菌的95%以上,其中子囊菌門的相對(duì)豐度占50%左右。在綱的分類水平下,座囊菌綱(dothideomycetes)、糞殼菌綱(sordariomycetes)、傘菌綱(agaricomycetes)、盤菌綱(Pezizomycetes)、球囊菌綱(Glomeromycetes)等五種真菌相對(duì)豐度占60%-80%。在目的分類水平下,格孢腔菌目(Pleosporales)、盤菌目(Pezizales)、傘菌目(Agaricales)、肉座菌目(Hypocreales)、球囊菌目(Glomerales)等五種真菌相對(duì)豐度占75%-85%。細(xì)菌中的放線菌門和真菌中的子囊菌門在植物莖葉分解過程中起著非常重要的作用;植物莖葉的分解能夠使土壤中真菌的優(yōu)勢(shì)種群個(gè)體數(shù)明顯增多;土壤真菌數(shù)量與植物莖葉分解前期初始基質(zhì)含量有關(guān)。
[Abstract]:Since the state implemented the policy of returning farmland to forests and grasslands, the vegetation restoration on the Loess Plateau has achieved some results, and a large number of plant stems and leaves have accumulated on the ground. The accumulation and decomposition of plant stems and leaves can change soil microenvironment, increase soil nutrient content, and increase soil microbial diversity. In this study, three typical herbaceous vegetations in this area were selected as the research object, and the decomposition of plant stems and leaves was simulated by field decomposition bag method. The effects of vegetation and treatment on soil properties provide basic scientific basis for vegetation restoration and ecosystem biodiversity restoration in the Loess Plateau. The main conclusions are as follows: (1) The release of nutrient elements from plant stems and leaves is obviously seasonal, but the release of nutrient elements from different treatments is not significantly different. The initial nitrogen content of BLX was the lowest, and the initial lignin and cellulose content were the highest, which led to the lower decomposition rate of stems and leaves of BLX and BLX-containing treatments, and the nutrient loss of BLX-containing treatments at the end of decomposition was lower. The leaching, enrichment and release of organic carbon appeared in the decomposition process. The leaching and degradation of soluble substances and carbohydrates in the early decomposition stage made the organic carbon release rapidly, and the proportion of lignin and cellulose in the late decomposition stage increased, which made the decomposition slow. The initial time of phosphorus enrichment was different between the treatments of each combination and the treatments of single plant. CMC and BLX began to enrich slowly after 45 days of interpretation and release, while the combination treatments and TGH began to enrich slowly after 45 days of interpretation and release. Lignin decomposition was not obvious until 390 days after decomposition. Cellulose did not change significantly 90 days before decomposition. After decomposition, the decomposition rate of CMC stem and leaf was the fastest and the decomposition amount was the largest. (2) The change trend of soil nutrients and the change trend of blank soil were basically the same. The results showed that the effect of decomposition of plant stems and leaves on soil nutrients was mainly affected by the changes of external water and heat conditions. The chemical composition of plant stems and leaves is closely related. Soil total nitrogen mainly comes from the organic matter formed by the decomposition of plant stems and leaves, so soil total nitrogen and organic carbon have similar changing trend. Soil total nitrogen and organic carbon content reach the highest value after 135 days of decomposition. Soil available phosphorus content began to increase slowly in summer when rainwater was sufficient. Soil ammonium nitrogen content decreased and nitrate nitrogen content increased at the initial stage of plant stem and leaf decomposition. Soil ammonium nitrogen content did not change significantly during the whole decomposition process. The effect of plant stem and leaf decomposition on soil available nitrogen content was mainly manifested in nitrate nitrogen content change. (3) The activity of soil enzymes is greatly influenced by environmental factors, and is less affected by the decomposition of plant stems and leaves. The initial nutrient status of soil will affect soil enzyme activity to a certain extent. Soil organic carbon, total nitrogen, available nitrogen and so on have a significant impact on soil urease, invertase, cellulase and alkaline phosphatase activity, and the content of soil available phosphorus and soil available phosphorus content. Soil alkaline phosphatase activity was negatively correlated. Plant stem and leaf decomposition could improve soil nutrient status and soil environment. At the end of plant stem and leaf decomposition, soil urease, sucrase and cellulase activity increased, while soil alkaline phosphatase activity decreased, which might be due to alkaline phosphatase mineralization of soil phosphorus. Mixed decomposition of plant stems and leaves could improve soil enzyme activity and soil nutrient status, but there was no significant difference in the increase and decrease of soil enzyme activity among treatments. (4) Soil microbial biomass was greatly affected by environmental conditions, while the initial nutrient content and stoichiometry of soil and plant stems and leaves were affected by environmental conditions. The ratio of MBN to MBC was the main reason for the difference of MBN and MBC contents in different treatments. At the end of decomposition test, MBC and MBN contents were positively correlated with soil and plant stem and leaf initial total nitrogen, total phosphorus, lignin content at 0.01 level, and soil MBN content was positively correlated with soil initial total nitrogen content, the correlation coefficient was 0.909 (p0.01). at the early decomposition stage, the decomposition of organic matter in plant stem and leaf was easy. The release of nutrients supplemented the content of soil nutrients and accelerated the metabolism of soil microorganisms. Microorganisms used sufficient carbon sources for their own growth and reproduction, and assimilated litter carbon into biological carbon, resulting in the increase of soil mbc. With the decomposition of plant stems and leaves, the accumulation of difficult-to-decompose substances such as cellulose and lignin led to the subsequent growth of soil microorganisms. Similarly, the decomposition of plant stems and leaves and the release of nutrients accelerated the mineralization of soil. The proliferation of microorganisms led to the increase of soil mbn. As the decomposition of plant stems and leaves proceeded, the large amount of nitrogen consumption in soil could not meet the micro-level. The microbial biomass of each combination was slightly higher than that of the single plant treatment at the late stage of plant stem and leaf decomposition, but the difference was not obvious. there was no significant difference in soil microbial biomass between different combinations, and there was no significant difference in soil microbial biomass between individual plants. (5) Soil microbial characteristics after 435 days of decomposition of plant stems and leaves under different treatments were studied by high-throughput sequencing technique. Ace index and Chao index of soil bacteria and fungi in the treatment of plant stems and leaves were higher than those in the blank treatment, and Simpson index was higher. The number of soil bacteria was less than that of blank treatment, and the Shannon index was higher than that of blank treatment, and the difference was significant at 0.05 level, indicating that the decomposition of plant stems and leaves could significantly increase the abundance of soil bacteria and fungi, and increase the diversity of soil bacteria. The relative abundance of several bacteria accounted for more than 90% of all bacteria in the soil, and the relative abundance of actinomycetes accounted for about 40%. The relative abundance of Ascomycetes is about 50%. At the classification level, the relative abundance of five fungi, including dothideomycetes, sordariomycetes, agaricomycetes, Pezizomycetes and Glomeromycetes, accounts for 60%-80%. The relative abundance of five fungi (Pleosporales, Pezizales, Agaricales, Hypocreales, Glomerales) is 75% - 85%. Actinomycetes in bacteria and Ascomycetes in fungi play an important role in the decomposition of plant stems and leaves. The number of dominant soil fungi increased significantly, and the number of soil fungi was related to the initial matrix content in the early stage of plant stem and leaf decomposition.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：S158;S154.3
本文編號(hào)：2220726
[Abstract]:Since the state implemented the policy of returning farmland to forests and grasslands, the vegetation restoration on the Loess Plateau has achieved some results, and a large number of plant stems and leaves have accumulated on the ground. The accumulation and decomposition of plant stems and leaves can change soil microenvironment, increase soil nutrient content, and increase soil microbial diversity. In this study, three typical herbaceous vegetations in this area were selected as the research object, and the decomposition of plant stems and leaves was simulated by field decomposition bag method. The effects of vegetation and treatment on soil properties provide basic scientific basis for vegetation restoration and ecosystem biodiversity restoration in the Loess Plateau. The main conclusions are as follows: (1) The release of nutrient elements from plant stems and leaves is obviously seasonal, but the release of nutrient elements from different treatments is not significantly different. The initial nitrogen content of BLX was the lowest, and the initial lignin and cellulose content were the highest, which led to the lower decomposition rate of stems and leaves of BLX and BLX-containing treatments, and the nutrient loss of BLX-containing treatments at the end of decomposition was lower. The leaching, enrichment and release of organic carbon appeared in the decomposition process. The leaching and degradation of soluble substances and carbohydrates in the early decomposition stage made the organic carbon release rapidly, and the proportion of lignin and cellulose in the late decomposition stage increased, which made the decomposition slow. The initial time of phosphorus enrichment was different between the treatments of each combination and the treatments of single plant. CMC and BLX began to enrich slowly after 45 days of interpretation and release, while the combination treatments and TGH began to enrich slowly after 45 days of interpretation and release. Lignin decomposition was not obvious until 390 days after decomposition. Cellulose did not change significantly 90 days before decomposition. After decomposition, the decomposition rate of CMC stem and leaf was the fastest and the decomposition amount was the largest. (2) The change trend of soil nutrients and the change trend of blank soil were basically the same. The results showed that the effect of decomposition of plant stems and leaves on soil nutrients was mainly affected by the changes of external water and heat conditions. The chemical composition of plant stems and leaves is closely related. Soil total nitrogen mainly comes from the organic matter formed by the decomposition of plant stems and leaves, so soil total nitrogen and organic carbon have similar changing trend. Soil total nitrogen and organic carbon content reach the highest value after 135 days of decomposition. Soil available phosphorus content began to increase slowly in summer when rainwater was sufficient. Soil ammonium nitrogen content decreased and nitrate nitrogen content increased at the initial stage of plant stem and leaf decomposition. Soil ammonium nitrogen content did not change significantly during the whole decomposition process. The effect of plant stem and leaf decomposition on soil available nitrogen content was mainly manifested in nitrate nitrogen content change. (3) The activity of soil enzymes is greatly influenced by environmental factors, and is less affected by the decomposition of plant stems and leaves. The initial nutrient status of soil will affect soil enzyme activity to a certain extent. Soil organic carbon, total nitrogen, available nitrogen and so on have a significant impact on soil urease, invertase, cellulase and alkaline phosphatase activity, and the content of soil available phosphorus and soil available phosphorus content. Soil alkaline phosphatase activity was negatively correlated. Plant stem and leaf decomposition could improve soil nutrient status and soil environment. At the end of plant stem and leaf decomposition, soil urease, sucrase and cellulase activity increased, while soil alkaline phosphatase activity decreased, which might be due to alkaline phosphatase mineralization of soil phosphorus. Mixed decomposition of plant stems and leaves could improve soil enzyme activity and soil nutrient status, but there was no significant difference in the increase and decrease of soil enzyme activity among treatments. (4) Soil microbial biomass was greatly affected by environmental conditions, while the initial nutrient content and stoichiometry of soil and plant stems and leaves were affected by environmental conditions. The ratio of MBN to MBC was the main reason for the difference of MBN and MBC contents in different treatments. At the end of decomposition test, MBC and MBN contents were positively correlated with soil and plant stem and leaf initial total nitrogen, total phosphorus, lignin content at 0.01 level, and soil MBN content was positively correlated with soil initial total nitrogen content, the correlation coefficient was 0.909 (p0.01). at the early decomposition stage, the decomposition of organic matter in plant stem and leaf was easy. The release of nutrients supplemented the content of soil nutrients and accelerated the metabolism of soil microorganisms. Microorganisms used sufficient carbon sources for their own growth and reproduction, and assimilated litter carbon into biological carbon, resulting in the increase of soil mbc. With the decomposition of plant stems and leaves, the accumulation of difficult-to-decompose substances such as cellulose and lignin led to the subsequent growth of soil microorganisms. Similarly, the decomposition of plant stems and leaves and the release of nutrients accelerated the mineralization of soil. The proliferation of microorganisms led to the increase of soil mbn. As the decomposition of plant stems and leaves proceeded, the large amount of nitrogen consumption in soil could not meet the micro-level. The microbial biomass of each combination was slightly higher than that of the single plant treatment at the late stage of plant stem and leaf decomposition, but the difference was not obvious. there was no significant difference in soil microbial biomass between different combinations, and there was no significant difference in soil microbial biomass between individual plants. (5) Soil microbial characteristics after 435 days of decomposition of plant stems and leaves under different treatments were studied by high-throughput sequencing technique. Ace index and Chao index of soil bacteria and fungi in the treatment of plant stems and leaves were higher than those in the blank treatment, and Simpson index was higher. The number of soil bacteria was less than that of blank treatment, and the Shannon index was higher than that of blank treatment, and the difference was significant at 0.05 level, indicating that the decomposition of plant stems and leaves could significantly increase the abundance of soil bacteria and fungi, and increase the diversity of soil bacteria. The relative abundance of several bacteria accounted for more than 90% of all bacteria in the soil, and the relative abundance of actinomycetes accounted for about 40%. The relative abundance of Ascomycetes is about 50%. At the classification level, the relative abundance of five fungi, including dothideomycetes, sordariomycetes, agaricomycetes, Pezizomycetes and Glomeromycetes, accounts for 60%-80%. The relative abundance of five fungi (Pleosporales, Pezizales, Agaricales, Hypocreales, Glomerales) is 75% - 85%. Actinomycetes in bacteria and Ascomycetes in fungi play an important role in the decomposition of plant stems and leaves. The number of dominant soil fungi increased significantly, and the number of soil fungi was related to the initial matrix content in the early stage of plant stem and leaf decomposition.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：S158;S154.3
【相似文獻(xiàn)】
相關(guān)碩士學(xué)位論文 前1條
1 李鑫;寧南山區(qū)典型植物莖葉分解過程及其對(duì)土壤養(yǎng)分和微生物群落的影響[D];西北農(nóng)林科技大學(xué);2016年
，本文編號(hào)：2220726
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