本文關(guān)鍵詞： N成對(duì)標(biāo)記 MCMC數(shù)值優(yōu)化模型 氮初級(jí)轉(zhuǎn)化速率 保氮機(jī)制　出處：《土壤》2017年02期 　論文類(lèi)型：期刊論文

【摘要】：利用~(15)N穩(wěn)定同位素成對(duì)標(biāo)記法并結(jié)合MCMC數(shù)值模型,研究了戴云山國(guó)家級(jí)自然保護(hù)區(qū)天然毛竹林(BF)及其鄰近黃山松 杉木林(NF)土壤氮素初級(jí)轉(zhuǎn)化速率,以評(píng)估該地區(qū)森林生態(tài)系統(tǒng)土壤氮狀態(tài),并分析其保氮機(jī)制。結(jié)果表明:BF土壤NH_4~+-N的總產(chǎn)生速率(以N量計(jì),13.16μg/(g×d))是NF土壤的2倍(6.25μg/(g×d)),其中黏土礦物對(duì)NH_4~+-N的解吸作用是BF產(chǎn)生NH_4~+-N的主要過(guò)程(55%),而NF主要以有機(jī)氮的礦化作用為主(56%)。BF土壤氮素初級(jí)礦化速率為5.56μg/(g×d),顯著高于NF的3.40μg/(g×d)。土壤氮素初級(jí)礦化速率與土壤全氮含量顯著正相關(guān)(P0.05),而與C/N比表現(xiàn)顯著負(fù)相關(guān)(P0.05)。BF與NF土壤NH_4~+-N總產(chǎn)生量的90%均被土壤微生物的同化作用以及黏土礦物的吸附作用所消耗。兩種土壤的硝化作用微弱,BF土壤總硝化速率(以N量計(jì),0.23μg/(g×d))與NF土壤(0.26μg/(g×d))相差不大。兩種林地土壤硝化作用均以有機(jī)氮的異養(yǎng)硝化為主,自養(yǎng)硝化過(guò)程可忽略不計(jì)。BF與NF土壤中NO_3~ -N消耗速率均超過(guò)了產(chǎn)生速率,表明BF與NF土壤均能有效降低NO_3~ -N的潛在淋失風(fēng)險(xiǎn),其中BF土壤中NO_3~ -N的消耗以微生物的同化作用為主(58%),而NF土壤以NO_3~ -N異化還原為NH_4~+-N過(guò)程為主(68%)。戴云山國(guó)家級(jí)自然保護(hù)區(qū)兩種亞熱帶森林土壤的氮轉(zhuǎn)化過(guò)程均以NH_4~+-N轉(zhuǎn)化為主,產(chǎn)生的絕大多數(shù)NH_4~+-N會(huì)迅速通過(guò)微生物對(duì)NH_4~+-N的同化作用以及黏土礦物對(duì)NH_4~+-N的吸附作用固持到有機(jī)氮庫(kù)中;自養(yǎng)硝化過(guò)程微弱,使得無(wú)機(jī)氮主要以NH_4~+-N的形式保存于土壤中,同時(shí)酸性土壤環(huán)境有效削弱了NH_4~+-N的揮發(fā)損失。此外,相對(duì)較高的NO_3~ -N微生物同化速率以及異化還原為NH_4~+-N速率,進(jìn)一步有效降低了NO_3~ -N的淋溶損失以及反硝化作用的氣態(tài)損失風(fēng)險(xiǎn),使該地區(qū)森林土壤能夠在多雨的條件下有效保持氮素,滿足植物的生長(zhǎng)需求。
[Abstract]:With the method of stable isotope pairwise labeling and MCMC numerical model, the primary nitrogen conversion rate of natural Phyllostachys pubescens forest in Dayunshan National Nature Reserve and its adjacent forest of Pinus tabulaeformis was studied. To assess the soil nitrogen status of forest ecosystems in the region, The results show that the total production rate of NH4- N (measured by N = 13.16 渭 g / g 脳 dU) is 2 times higher than that of NF soil (6.25 渭 g / g / d), and the desorption of NH4- N by clay minerals is the main process of NH4- N production in BF, while NF mainly consists of NH4- N in BF. The primary mineralization rate of nitrogen was 5.56 渭 g / g 脳 d1, which was significantly higher than that of NF 3.40 渭 g / g 脳 d.There was a significant positive correlation between soil nitrogen primary mineralization rate and soil total nitrogen content (P0.05), but a significant negative correlation with C / N ratio (P0.05N). BF was negatively correlated with NF soil NH4- N level. 90% of the total production was consumed by soil microbial assimilation and clay mineral adsorption. The nitrification of the two soils was weak and the total nitrification rate (measured by N = 0.23 渭 g / g / g / d) was similar to that of NF 0.26 渭 g / g / d ~ (-1). Soil nitrification in woodland was dominated by heterotrophic nitrification of organic nitrogen. The autotrophic nitrification process was negligible, and the consumption rate of NO3- N in soil of NF and BF exceeded the production rate, which indicated that both BF and NF soil could effectively reduce the potential leaching risk of NO3 ~ + -N in soil. The consumption of NO3 ~ -N in BF soil was mainly caused by the assimilation of microbes, while in NF soil, no _ 3 ~ + -N was mainly reduced to NH _ 4 ~ -N. The nitrogen transformation process of the two subtropical forest soils in Dayunshan National Nature Reserve was mainly composed of NH _ 4 ~ -N conversion. The vast majority of NH4- N produced will be rapidly consolidated into the organic nitrogen pool through the assimilation of NH4- N by microbes and the adsorption of NH4- N by clay minerals, and the autotrophic nitrification process is weak, so that inorganic nitrogen is mainly stored in the soil in the form of NH4- N. At the same time, the volatilization loss of NH4- N was effectively weakened by acidic soil environment. In addition, the relatively high assimilation rate of NOS3 ~ -N and the rate of alienation reduction to NH4- N were also relatively high. Furthermore, the leaching loss of no _ 3- N and the gas loss risk of denitrification can be reduced effectively, so that the forest soil in this area can effectively maintain nitrogen under the condition of heavy rain, and meet the plant growth needs.
【作者單位】： 南京師范大學(xué)地理科學(xué)學(xué)院;戴云山國(guó)家級(jí)自然保護(hù)區(qū)管理局;江蘇省地理環(huán)境演化國(guó)家重點(diǎn)實(shí)驗(yàn)室培育建設(shè)點(diǎn);江蘇省地理信息資源開(kāi)發(fā)與利用協(xié)同創(chuàng)新中心;南京師范大學(xué)虛擬地理環(huán)境教育部重點(diǎn)實(shí)驗(yàn)室;
【基金】：國(guó)家重大科學(xué)研究計(jì)劃項(xiàng)目(2014CB953803) 江蘇高校優(yōu)勢(shì)學(xué)科建設(shè)工程項(xiàng)目資助
【分類(lèi)號(hào)】：S714
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本文編號(hào)：1496776