氮添加對(duì)人工油松林葉凋落物分解的影響
發(fā)布時(shí)間：2019-01-17 10:44
【摘要】：凋落物分解是森林生態(tài)系統(tǒng)物質(zhì)循環(huán)和能量流動(dòng)的重要環(huán)節(jié)。目前持續(xù)增加的氮(N)沉降正在顯著影響著森林生態(tài)系統(tǒng)的物質(zhì)循環(huán)和能量流動(dòng)過程。然而對(duì)于N沉降對(duì)凋落物分解的過程和機(jī)制還不是十分清楚。對(duì)此,本研究于2014年至2016年,在宜川鐵龍灣林場(chǎng)對(duì)人工油松林進(jìn)行N添加實(shí)驗(yàn),共設(shè)置4個(gè)N添加處理(0,3,6,9gNm-2a-1),通過埋袋法研究N添加條件下油松葉凋落物分解動(dòng)態(tài)過程變化規(guī)律,所得結(jié)果如下:(1)葉凋落物分解具有明顯的階段性:分解初期(0-60天)凋落葉分解速率較高,中期(60-180天)分解較慢,在后期(180-300天)分解速率有所增高,分解300天后凋落物質(zhì)量殘留率分別為72.66%(CK)、72.40%(N3)、69.08%(N6)、70.11%(N9)。利用Olson指數(shù)衰減模型求得各處理的分解系數(shù),各處理分解系數(shù)k值為0.368(CK)、0.341(N3)、0.424(N6)、0.388(N9)。(2)N添加增加了葉凋落物初始N含量,P含量和NSC含量,對(duì)初始C含量和木質(zhì)素含量影響較小。N添加處理對(duì)凋落物元素和化學(xué)組成含量以及化學(xué)計(jì)量比有不同的作用:N添加促進(jìn)了 C元素的釋放;N3處理凋落物N含量顯著高于CK和N6處理,而初始N含量越高,N釋放速率越快;N添加對(duì)分解過程中P元素的影響較小;N添加對(duì)凋落物NSC降解有促進(jìn)作用;N3處理對(duì)木質(zhì)素降解影響較小,N6和N9處理顯著促進(jìn)了木質(zhì)素降解;分解過程中施N處理的C/N、C/P、木質(zhì)素/N低于CK處理。(3)短期N添加對(duì)表層土壤水穩(wěn)性團(tuán)聚體含量無顯著影響;隨著N添加水平增加,大、微團(tuán)聚體有機(jī)碳含量,大、微團(tuán)聚體中活性和高活性有機(jī)碳含量呈先升高后降低的變化規(guī)律,并在N6處理(6 gNm-2 a-1)下上述各指標(biāo)達(dá)到最大。短期N添加主要通過影響表層大、微團(tuán)聚體中的中活性有機(jī)碳進(jìn)而影響土壤表層有機(jī)碳含量。主成分分析表明,N添加改變了土壤理化性質(zhì),進(jìn)而導(dǎo)致根系生物量增加和凋落物分解,是表層土壤團(tuán)聚體活性有機(jī)碳變化的主要原因。(4)通徑分析表明,不同處理下影響凋落物分解的因素不盡相同,木質(zhì)素含量是影響凋落物分解的主要因素。N添加對(duì)木質(zhì)素降解的影響大小與N添加量以及受之影響的凋落物基質(zhì)質(zhì)量和分解環(huán)境有關(guān)。CK和N3處理會(huì)因?yàn)槿~凋落物N含量的影響使木質(zhì)素降解受到抑制。總之,低N(3 gN·m-2·a-1)添加對(duì)人工油松林葉凋落物分解無影響,中N(6gN·m-2·a-1)和高N(9gN·m-2·a-1)添加加快了葉凋落物分解。利用凋落物初始N含量、C/N、C/P、木質(zhì)素/N并不能夠準(zhǔn)確預(yù)測(cè)凋落物的分解過程,而木質(zhì)素含量能很好地預(yù)測(cè)凋落物分解。
[Abstract]:Litter decomposition is an important link of material circulation and energy flow in forest ecosystem. At present, the increasing nitrogen (N) deposition is significantly affecting the material cycle and energy flow process of forest ecosystem. However, the process and mechanism of N deposition for litter decomposition are not well understood. From 2014 to 2016, the experiment was carried out on artificial Pinus tabulaeformis forest in Tielongwan Forest Farm, Yichuan. The dynamic process of litter decomposition of Pinus tabulaeformis was studied by burying bag method. The results were as follows: (1) the decomposition rate of leaf litter in the early stage (0-60 days) was higher than that in the early stage (0-60 days). The decomposition rate increased in the late stage (180-300 days), and the residual rate of litter weight was 72.66% (CK), (N3) and 69.08% (N6), respectively, in the middle period (60-180 days). 70.11% (N9). The decomposition coefficients of each treatment were obtained by using Olson exponent attenuation model. The decomposition coefficients of each treatment were 0.368 (CK), 0.341 (N3), 0.424 (N6), 0.388 (N9). (2) N, and the initial N content of leaf litter was increased. P content and NSC content had little effect on initial C content and lignin content. N addition had different effects on litter element and chemical composition content and stoichiometric ratio. The N content of litter in N _ 3 treatment was significantly higher than that in CK and N _ 6 treatments, but the higher the initial N content was, the faster the N release rate was, the smaller the effect of N addition on the decomposition of P element, and the effect of N addition on the degradation of NSC in litter. N3 treatment had little effect on lignin degradation, while N6 and N9 treatments significantly promoted lignin degradation. The lignin / N ratio of C / N / P in N treatment was lower than that in CK treatment. (3) Short-term N addition had no significant effect on the content of water-stable aggregates in surface soil. With the increase of N addition level, the content of organic carbon in microaggregates and microaggregates increased first and then decreased, while the content of active and highly active organic carbon in microaggregates increased first and then decreased. Under N6 treatment (6 gNm-2 a-1), the above indexes reached the maximum. Short-term N addition mainly affected the content of soil surface organic carbon by influencing the content of medium active organic carbon in microaggregates. Principal component analysis (PCA) showed that N addition changed soil physical and chemical properties, which led to the increase of root biomass and decomposition of litter, which was the main reason for the change of active organic carbon in surface soil aggregates. (4) path analysis showed that: 1. The factors affecting litter decomposition were different under different treatments. Lignin content is the main factor affecting litter decomposition. The effect of N addition on lignin degradation is related to N addition and the quality of litter substrate affected by N addition and decomposition environment. CK and N3 treatment will cause leaf withering. The degradation of lignin was inhibited by the effect of N content. In conclusion, low N (3 gN m-2 a-1) addition had no effect on leaf litter decomposition in artificial Pinus tabulaeformis forest, but medium N (6gN m-2 a-1) and high N (9gN m-2 a-1) increased leaf litter decomposition. Using the initial N content of litter, C / N / P, lignin / N could not accurately predict the decomposition process of litter, but lignin content could predict litter decomposition very well.
【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】：2017
【分類號(hào)】：S714
本文編號(hào)：2409981
[Abstract]:Litter decomposition is an important link of material circulation and energy flow in forest ecosystem. At present, the increasing nitrogen (N) deposition is significantly affecting the material cycle and energy flow process of forest ecosystem. However, the process and mechanism of N deposition for litter decomposition are not well understood. From 2014 to 2016, the experiment was carried out on artificial Pinus tabulaeformis forest in Tielongwan Forest Farm, Yichuan. The dynamic process of litter decomposition of Pinus tabulaeformis was studied by burying bag method. The results were as follows: (1) the decomposition rate of leaf litter in the early stage (0-60 days) was higher than that in the early stage (0-60 days). The decomposition rate increased in the late stage (180-300 days), and the residual rate of litter weight was 72.66% (CK), (N3) and 69.08% (N6), respectively, in the middle period (60-180 days). 70.11% (N9). The decomposition coefficients of each treatment were obtained by using Olson exponent attenuation model. The decomposition coefficients of each treatment were 0.368 (CK), 0.341 (N3), 0.424 (N6), 0.388 (N9). (2) N, and the initial N content of leaf litter was increased. P content and NSC content had little effect on initial C content and lignin content. N addition had different effects on litter element and chemical composition content and stoichiometric ratio. The N content of litter in N _ 3 treatment was significantly higher than that in CK and N _ 6 treatments, but the higher the initial N content was, the faster the N release rate was, the smaller the effect of N addition on the decomposition of P element, and the effect of N addition on the degradation of NSC in litter. N3 treatment had little effect on lignin degradation, while N6 and N9 treatments significantly promoted lignin degradation. The lignin / N ratio of C / N / P in N treatment was lower than that in CK treatment. (3) Short-term N addition had no significant effect on the content of water-stable aggregates in surface soil. With the increase of N addition level, the content of organic carbon in microaggregates and microaggregates increased first and then decreased, while the content of active and highly active organic carbon in microaggregates increased first and then decreased. Under N6 treatment (6 gNm-2 a-1), the above indexes reached the maximum. Short-term N addition mainly affected the content of soil surface organic carbon by influencing the content of medium active organic carbon in microaggregates. Principal component analysis (PCA) showed that N addition changed soil physical and chemical properties, which led to the increase of root biomass and decomposition of litter, which was the main reason for the change of active organic carbon in surface soil aggregates. (4) path analysis showed that: 1. The factors affecting litter decomposition were different under different treatments. Lignin content is the main factor affecting litter decomposition. The effect of N addition on lignin degradation is related to N addition and the quality of litter substrate affected by N addition and decomposition environment. CK and N3 treatment will cause leaf withering. The degradation of lignin was inhibited by the effect of N content. In conclusion, low N (3 gN m-2 a-1) addition had no effect on leaf litter decomposition in artificial Pinus tabulaeformis forest, but medium N (6gN m-2 a-1) and high N (9gN m-2 a-1) increased leaf litter decomposition. Using the initial N content of litter, C / N / P, lignin / N could not accurately predict the decomposition process of litter, but lignin content could predict litter decomposition very well.
【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】：2017
【分類號(hào)】：S714
【引證文獻(xiàn)】
相關(guān)碩士學(xué)位論文 前1條
1 史君怡;間伐和林下引種對(duì)人工刺槐林群落特征的影響[D];西北農(nóng)林科技大學(xué);2018年
，本文編號(hào)：2409981
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