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1.
为了阐明人工梭梭林土壤碳氮磷密度及其生态化学计量特征演变规律,以吉兰泰荒漠区不同林龄(3,6,11,16年)人工梭梭林为研究对象,分析0—20,20—40,40—60 cm土层土壤有机碳(SOC)、全氮(TN)、全磷(TP)密度和生态化学计量特征。结果表明:(1)4种林龄人工梭梭林0—60 cm土层SOC、TN含量及其密度随林龄增加而升高,而TP含量及其密度随林龄增加而降低。其中,3,6年梭梭林SOC、TN含量及其密度随土层深度增加而升高,TP含量及其密度则与之相反;11,16年梭梭林SOC、TN、TP含量及其密度随土层深度增加而降低。(2)4种林龄梭梭林土壤C∶N、C∶P、N∶P分别为2.24~9.21,1.59~7.05,0.56~0.81,均属于中等变异水平,且变异系数随林龄和土层深度增加逐渐减小,说明土壤C∶N、C∶P、[JP]N∶P趋于平稳状态。(3)林龄、土层深度及其交互作用显著影响SOC含量、SOC密度、C∶N、C∶P,对TN含量、TP含量、TN密度、TP密度、N∶P无显著影响。(4)土壤孔隙度(STP)与SOC密度呈显著正相关关系(P＜0.05),说明土壤孔隙度增加有助于SOC密度增加,提高土壤肥力。在干旱荒漠区建植梭梭林有利于提高土壤肥力,改善干旱荒漠区土壤环境。  相似文献   

2.
荒漠草原中不同密度人工柠条灌丛土壤化学计量特征   总被引：8，自引：2，他引：6  
为了揭示人工灌草结合的生态系统土壤内部C,N,P平衡和循环过程,以荒漠草原为对照(CK),研究了相同林龄不同密度(高密度HD、中密度MD、低密度LD)人工柠条灌丛土壤化学计量特征。结果表明,柠条灌丛0—100cm土层平均有机碳(SOC)、全氮(TN),全磷(TP)和氮磷比(N/P)随密度的增加呈上升趋势,碳氮比(C/N),碳磷比(C/P)呈降低趋势,其中TP的空间变异性较高;垂直方向SOC,C/N和C/P随土层深度的增加呈单峰曲线,TN,TP和N/P在0—40cm土层呈锐减趋势,40cm土层以下缓慢降低并趋于稳定;0—40cm土层TN和TP含量占总含量的61.82%和55.56%,可作为密度变化对人工柠条灌丛土壤养分的敏感指标;相关分析结果发现,人工柠条灌丛土壤N和P含量呈极显著正相关(p0.01),二者均与C/N呈极显著的负相关(p0.01),说明柠条对土壤中N和P两种元素需求相一致。  相似文献   

3.
【目的】秸秆还田是提升农田土壤肥力,改善土壤养分含量及有效性的重要措施。我们分析了东北黑土区不同秸秆还田方式下土壤碳氮磷钾含量和玉米产量的年际变化,并从土壤化学计量特征角度研究了土壤养分的有效性。【方法】依托2012年在东北黑土区建立的秸秆还田长期定位试验,选取秸秆移除(CK)、秸秆混合还入0—20 cm耕层(RI)和秸秆覆盖还田(RC) 3个处理,测定了处理实施1年(2013)、3年(2015)、5年(2017)和8年(2020)后,不同土层土壤有机碳(SOC)、全氮(TN)、全磷(TP)、全钾(TK)含量及玉米产量,计算了土壤化学计量特征(C∶N、C∶P、N∶P),并分析了各指标之间的相关性。【结果】随试验年限的增加,在0—20 cm土层,CK处理SOC含量有所下降,TN含量基本保持不变,而RI和RC处理的SOC和TN含量均有所增加,RC处理下均为最高;RI处理的SOC和TN含量在0—20 cm土层分布相对均匀,RC处理SOC和TN含量在0—5 cm土层中明显增加,尤其在试验5～8年间的增幅明显升高。CK、RI和RC 3个处理的TP和TK含量均随试验年限的增加缓慢升高,处理间无显著...  相似文献   

4.
不同演化阶段白刺灌丛沙堆土壤生态化学计量特征   总被引：1，自引：1，他引：0  
为了阐明灌丛沙堆发育对土壤碳(C)、氮(N)、磷(P)生态化学计量特征的影响,以吉兰泰荒漠区不同演化阶段白刺(Nitraria tangutorun)灌丛沙堆为研究对象,研究0—100 cm土层土壤C∶N∶P化学计量特征在不同演化阶段的变化规律和垂直分布规律。结果表明:(1)白刺灌丛沙堆土壤有机碳(SOC)、全氮(TN)和全磷(TP)随演化阶段(雏形阶段→发育阶段→稳定阶段→衰亡阶段)的变化呈先增后减的变化趋势。演化阶段对白刺灌丛沙堆SOC影响显著(P<0.05),对TN、TP无显著影响(P>0.05),其SOC、TN、TP均值含量在0—100 cm土层分别为0.42~0.58,0.04~0.07,0.22~0.25 g/kg,远小于全国土壤平均水平(11.12,1.06,0.65 g/kg)。(2)白刺灌丛沙堆SOC、TN、TP含量及其生态化学计量比随土层深度增加无明显规律性。(3)土壤SOC、TN、TP含量及其生态化学计量比均属于中等变异,且变异系数随白刺灌丛沙堆演化不断减小。(4)土壤容重、毛管孔隙度、非毛管孔隙度对白刺灌丛沙堆土壤TN、C∶N、N∶P影响显著,而土壤含水量、pH对白刺灌丛沙堆SOC、TN、TP含量及其生态化学计量比无显著影响。各演化阶段白刺灌丛沙堆SOC、TN是调控白刺灌丛沙堆土壤生态化学计量比的主要因素。因此,该研究结果明晰了白刺灌丛沙堆土壤C∶N∶P生态化学计量特征对不同演化阶段的响应,为该区域白刺群落的保护、利用和植被恢复与重建提供科学依据。  相似文献   

5.
采用空间代替时间的方法,选取贵州中部高原山地8,18,26,36年生4个林龄的马尾松人工林为研究对象,通过测定林下土壤有机碳(SOC)、全氮(TN)和全磷(TP)含量,分析不同发育阶段林分土壤养分变化规律及化学计量比特征。结果表明:马尾松人工林土壤SOC、TN、TP平均值分别为12.24,1.94,0.35g/kg,C∶N、C∶P和N∶P平均值分别为6.58,38.70和13.65,C∶N∶P的平均值为39∶6∶1,其养分含量总体不高。随土层深度增加,4个林龄土壤SOC、TN含量降低,但C∶N增加,TP、C∶P和N∶P无明显变化规律。随林龄增加,土壤SOC、TN、N∶P先降低后升高,而TP则持续降低;C∶N除在36年生林分中显著降低外,其余各林分均无显著差异;C∶P无明显变化规律。相关分析表明,SOC、TN是调控马尾松人工林土壤生态化学计量比的主要因素。研究结果可为进一步明确贵州高原山地马尾松人工林土壤养分循环特征提供重要参考。  相似文献   

6.
针叶林混交阔叶树是改善土壤肥力、增强林地养分循环的重要措施,而混交效应受到针叶树种自身特性的影响,马尾松(Pinus massoniana)和湿地松(P.elliottii)是亚热带地区广泛种植的针叶树种,但目前2种针叶林对阔叶树混交的响应特征还不清楚。选取马尾松、湿地松纯林以及木荷(Schima superba)补植后形成的马尾松—木荷和湿地松—木荷混交林为研究对象,采集剖面土壤样品,测定土壤容重、有机碳(OC)、全氮(TN)和全磷(TP)含量,计算碳氮磷储量及化学计量特征,比较不同森林类型间的异同。混交阔叶树显著增加了马尾松林0—60cm各土层OC含量,而湿地松纯林与其混交林间OC含量无显著差异。同时,混交增加了2种针叶林土壤TN含量。马尾松林混交后0—60cm土层碳储量显著增加95.8%,而混交阔叶树对湿地松林土壤碳储量无显著影响。混交阔叶树后马尾松和湿地松林0—60cm土壤总氮储量分别增加了15.8%和28.4%,但混交对土壤磷储量无显著影响。混交显著增加了马尾松林0—40cm各土层C/N,而降低了湿地松林0—10cm土层C/N。混交阔叶树后马尾松林0—20cm土层C/P和0—10cm土层N/P显著增加,而混交仅增加湿地林0—10cm土层N/P。混交阔叶树增加了针叶林土壤氮储量,但对磷储量无显著影响,同时混交改变了土壤碳氮磷生态化学计量特征。与湿地松林相比,马尾松林土壤养分含量、储量及其化学计量特征对混交的响应更敏感。  相似文献   

7.
石羊河流域干旱荒漠区人工梭梭林对土壤碳库的影响   总被引：3，自引：0，他引：3  
采用野外调查与室内分析相结合的方法,研究石羊河流域民勤干旱沙区种植人工梭梭林4,13,36年后的土壤有机碳(Soil organic carbon,SOC)、无机碳(Soil inorganic carbon,SIC)、全氮(Total nitrogen,TN)和总碳(soil total carbon,TC)含量及储量变化特征。结果表明:流动沙地种植梭梭后,0-50cm层灌丛下和行间SOC和TN含量总体随造林年限增加而增加,5-50cm层灌丛下SIC含量在13年梭梭林地最高。36,13年林地0-50cm层灌丛下SOC和TN储量均高于行间,而13年灌丛下SIC储量低于行间,4年灌丛下5-50cm层SOC、TN和SIC储量均低于行间。0-50cm层土壤有机碳、无机碳、全氮储量增幅分别为102.44%,24.66%,54.55%,36年林地SOC和TN储量随土层加深先降低后增加,但4,13年和流动沙地SOC、SIC和TN储量均随土层加深而增加。土壤有机碳占总碳比例随造林年限增加而增加。相关分析结果表明,土壤颗粒组成、造林年限、土层深度等与土壤有机碳和全氮储量显著相关(P0.01)。民勤干旱沙区造林提高了土壤碳库截存量,并且随林龄增长而增长。  相似文献   

8.
宁南山区不同年限撂荒梯田土壤碳氮磷化学计量特征   总被引：1，自引：0，他引：1  
为了探究不同年限撂荒梯田对土壤碳氮磷含量及其化学计量特征的影响,为宁南山区撂荒梯田的管理利用和植被恢复提供科学依据。选择宁南山区彭阳中庄示范区不同年限撂荒梯田(2,5,15,17,20 a)为研究对象,通过野外采样与室内测定相结合的方法,对研究区5个不同年限撂荒梯田0—60 cm土壤样品中的C,N,P元素含量及其化学计量比特征进行了分析。结果表明:在0—60 cm土层,不同年限撂荒梯田的土壤C,N分布规律一致,均随土层深度的增加而减小,表层0—10 cm出现了富集现象,且随着撂荒年限增加呈先降低后升高的趋势,其他4层呈波动式下降趋势,土壤全磷含量分布比较均匀。土壤C∶N随着不同撂荒年限的增加呈波动式升高趋势,撂荒20年0—40 cm土层土壤C∶N最高,并与其他各年呈显著性变化(p0.05)。土壤C∶P和N∶P均表现为在表层0—10 cm随着撂荒年限的增加,总体呈现出先降低后升高的趋势,其他各层总体呈现下降的趋势。土壤C∶P和N∶P随土层增加呈减小趋势。土壤C∶N与全N和土壤C含量相关性不显著。土壤C∶P与土壤C含量呈极显著的正相关,与全磷含量呈显著的正相关。土壤N∶P与土壤全N含量呈极显著的正相关,与全磷含量呈显著的正相关。通过上述分析,总体反映出撂荒梯田土壤碳氮磷及其化学计量比受到不同年限和土层深度的双重影响,农地弃耕撂荒演替对土壤肥力有一定程度的改善。  相似文献   

9.
北京主要河流河岸带实施平原造林工程后,对河岸带植被类型及土壤造成不同程度影响。研究河岸带原有及重建植被类型土壤生态化学计量特征,对河岸生态系统土壤碳氮磷平衡及固碳潜力提升提供科学依据。选取北京温榆河昌平段岸边原有植被类型3种样地(乔木林、乔灌林及草地),重建植被类型2种样地(乔木林与灌木林),共15个样方,采集3层(0—10,10—20,20—30 cm)土壤样品,分析并计算碳(C)、氮(N)和磷(P)含量及计量比。结果表明:原有与重建植被类型的土壤有机碳(SOC)、全氮(TN)、全磷(TP)含量分别为3.810~10.320,0.223~0.700,0.551~0.692 g/kg,C/N、N/P、C/P分别为11.592~25.373,0.373~1.022,5.662~15.493;SOC与TN均在表层聚集,且同N/P、C/P一样表现出随土层深度增加而减少趋势,C/N反之,TP受土层深度影响较小;原有植被类型(乔木林)土壤SOC和TN均高于其他植被类型,在10—20,20—30 cm土层间C/N、C/P均显著低于其他植被类型(P＜0.05);原有植被类型(草地)在0—10 cm土层间N/P最低;重建植被类型(乔木林)土壤TP含量显著低于其他植被类型;重建植被类型(灌木林) C/N显著高于其他植被类型。研究结果揭示了研究区土壤N素为植物生长的限制元素,乔木、乔灌林下土壤有机质释放更多,P有效性更高,固碳潜力强;重建植被类型有机质矿化较慢,固磷能力更强。因而,建议温榆河河岸带采用乔木纯林和乔灌混交模式来积累土壤有机质,提高河岸带生态系统土壤质量及固碳潜力。  相似文献   

10.
为阐明烤烟连作对土壤生态化学计量学特征的影响,采用野外调查与室内分析相结合的方法,对四川泸州烟区正茬和连作1、3、5年土壤的有机碳(SOC)、全氮(TN)、全磷(TP)和全钾(TK)含量及其化学计量特征进行了研究。结果表明:与正茬相比,烤烟连作1年对土壤养分含量无显著影响;连作至第3年时,SOC含量明显下降,而TP和TK含量显著上升;连作至第5年时,SOC含量显著下降了9.89%,TN、TP和TK则分别增加了14.37%、68.84%和27.58%。土壤C/N、C/P、N/P和N/K随连作年限的增加而降低,年均下降4.06%、9.25%、6.51%和2.36%。土壤SOC对C/N、C/P、N/P、N/K贡献为正,而TN、TP、TK对C/N、C/P、N/P贡献为负,土壤养分及其化学计量比的相关性受到各养分的共同影响。总体来看,烤烟在连作3年时即可引起土壤磷钾累积及有机碳降低,使其生态化学计量比发生变化,从而可能影响土壤养分间的平衡供应。  相似文献   

11.
Abstract

The seasonal patterns of foliage nutrient concentrations and contents were monitored for two growing seasons in an 11‐year—old Pinus el1iottii stand. In the first growing season after needle initiation, N, P, K, Mg, and Zn concentrations decreased, but this was followed by an increase in the fall and winter months. Another drop in concentration of all elements, except P, occurred in the second growing season. Decreases in total contents indicated that this drop was a result of translocation to other tissues. In contrast to the mobile elements, the concentration and fascicle contents of Ca, Mn, and Al increased with aging of the needles.

Between‐tree variability was least for N, P, and Zn and the N, K, Mg, Mn, and Zn in the current foliage had consistently lower variation than that in the 1‐year‐old foliage. Between‐tree variation for K was lower in the winter than the spring.

For pine foliage, recommended sampling period for N, P, Mg, and Zn is mid to late summer and for the other elements it is late fall to late winter.

There are several sources of variation that influence the level of nutrients in tree foliage. The most important of these, apart from the tree nutrient status, are seasonal fluctuations, variation between trees, and age of needles . Smaller sources of variation are associated with position of the needles within the crown, diurnal changes, year to year variation, and analytical errors1,2. These variables must be studied in order to develop suitable sampling techniques and in Pinus this has been undertaken for P. banksiana 1, P. taeda 3, P. strobus 4, P. resinosa 4, P. sylvestris 5, and P. radiata 6,7. However, foliage sampling has not been studied in detail for slash pine (Pinus elliottii Englem var. elliottii) and earlier studies with other pines have been largely confined to temperate or cool climates.

This study reports the variation in elemental concentrations with season, age of foliage, and between slash pine trees growing in a subtropical climate in Florida.  相似文献   

12.
The distribution of zinc, manganese, copper, cobalt, and nickel in Andosols was investigated. Sixty nine soil samples were collected from different horizons of an Andosols profile in Miyakonojo Basin in south Kyushu, Japan, The total contents of heavy metals were determined by digestion and four extraction solutions, 1 M NH4Ac (ammonium acetate) pH 4.5, 0.1 M HCl, 0.01 M EDTA (ethylenediaminetetraacetic acid) pH 6.5, and 0.005 M DTPA (diethylenetri-aminepentaacetic acid) pH 7.3 were used to determine the contents of available Zn, Mn, Cu, Co, and Ni in Andosols in relation to the organic carbon content. The results of the extraction analysis showed that by the use of 0.1 M H Cl high value of extracted heavy metals in the upper layers of the humus horizons were obtained while EDTA extraction yielded a large amount of the above mentioned metals in the high humus horizons. The extractable heavy metals contents were high and these metals closely related to the organic carbon content mostly in the humus horizons in the profile. Where, biocycling process may play an important role in the concentration of heavy metals. Based on the study, it was found that the total content of Zn increased towards the C horizons or pumice layers in the soil profile. Such a trend was also found in the case of the Mn content. While the Cu content in the humus horizons was much higher in the upper part of each humus horizon. According to this study the distribution of heavy metals, Cu (organic matter complexes) in the Andosols profile was more stable than that of Zn (organic matter complexes) in soils. It was shown that Zn in the surface humus horizon was enriched but that some amount was leached under buried conditions. The same phenomenon was also observed in the distribution of Mn in the profile. The movement of Co and Ni in the soil profile was limited, as evidenced by the sharp reduction in the concentrations of these two metals in buried soils.

Hence, it is concluded that the distribution of Zn, Mn, Cu, Co, and Ni was considerably higher in the humus horizons of the Andosols profiles.  相似文献   

13.
Metabolism of theanine, gamma-glutamylethylamide, in rats   总被引：8，自引：0，他引：8  
The metabolism of theanine, one of the major amino acid components in tea (Camellia sinensis), was studied in rats. High-performance liquid chromatography (HPLC) with fluorometric detection was used to evaluate the nature of theanine's metabolites in plasma, urine, and tissues. In the urine samples collected after administration of 100, 200, and 400 mg each of theanine, intact theanine, L-glutamic acid, and ethylamine, these compounds were detected in a dose-dependent manner. When 200 mg of theanine was orally administered to rats, the plasma concentrations of theanine and ethylamine reached their highest levels about 0.5 and 2 h after administration, respectively. It seems most likely that the enzymatic hydrolysis of theanine to glutamic acid and ethylamine was accomplished in the kidney. These results indicate that orally administered theanine is absorbed through the intestinal tract and hydrolyzed to glutamic acid and ethylamine in the rat kidney.  相似文献   

14.
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15.
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16.
The literature on the fluxes of six heavy metals in temperate forest ecosystems is reviewed. Special attention is given to wet and dry deposition and internal flux, to metal budgets for ecosystems and soils, to concentrations in aqueous compartments of the ecosystem and to speciation in soil solutions. Metal fluxes are discussed in relation to pollution load, soil type, tree species and land use. The mobility of Cu and Pb is strongly dependent on the solubility of organic matter. These metals are commonly accumulated in forest soils. Zinc, Cd and Ni are greatly influenced by soil acidity and are often lost in considerable amounts from acidified soils. Chromium is often at balance in forest ecosystems. Implications for metal solubility and budgets in forest soils are discussed in connection with an increase in soil acidification.  相似文献   

17.
Sandstorms which distribute a great number of particles are a special atmospheric occurrence and are uncommon in northern China. This study was conducted to determine, for the first time, the concentration of organochlorine pesticides (OCPs) in sandstorm depositions. Samples were collected from urban areas of Beijing and a total of eight OCPs were measured. All samples contained OCP residues. The total hexachlorocyclohexane (HCHs) concentration ranged from 20.6 to 59.8ng g?1 and the total dichlorodiphenyltrichloroethane (DDTs) concentration ranged from 12.0 to 14.3ng g?1. Furthermore, increasing HCH contamination was observed from the northwest to the southeast and a uniform distribution of DDT contamination was discovered in Beijing. Analysis of the sources of contamination showed that HCHs in the sandstorm depositions were derived from a relatively old source of lindane, and DDTs mainly originated from an old source of dicofol in Beijing. The preliminary pollution assessment of the samples indicated that HCH levels might be categorized as low pollution and DDT levels might be categorized as no pollution. The present study suggests that sandstorm depositions may not produce the special risk of adverse health effect from OCPs for the residents of Beijing, China.  相似文献   

18.
Replacing native plant types with introduced cultivars may have unexpected cropping system consequences. Native species and introduced cultivars may vary in their ability to form mycorrhizal symbioses with soil fungi and consequently affect phosphorus (P) nutrition. Low-input cropping systems often depend on mycorrhiza for adequate nutrition and growth, while high-input systems minimize the benefit of and need for colonization. Studies in wheat (Triticum aestivum L.) suggest that improving cultivars reduced the ability to form mycorrhiza. This study was conducted at six sites in the province of Chiquimula, Guatemala, to determine the difference in mycorrhizal infection rates between two maize (Zea mays L.) cultivars—‘Cushpeño,’ a native, open-pollinated variety, and ‘HB-83,’ an introduced, improved hybrid. The ‘HB-83’ was colonized at a significantly lower percentage (67%) than was ‘Cushpeño’ (72%; α = 0.0137). A strong negative correlation (r = ?0.953) existed between Mehlich-3 extractable soil P and differences in mycorrhizal colonization rates between the two genotypes. The full impact of lower colonization rates of the introduced hybrid on sustainability of the village agricultural system needs further investigation.  相似文献   

19.
The results of residue determinations of the growth promotors carbadox, tylosin, and virginiamycin in kidney, liver, and muscle from pigs in feeding experiments are described as well as the analytical methods used. Residues of the carbadox metabolite quinoxaline-2-carboxylic acid were found in liver from pigs fed 20 mg/kg in the diet with a withdrawal time of 30 days. No residues were detected in muscle with zero withdrawal time. The limit of determination was 0.01 mg/kg for both tissues. No residues of virginiamycin and tylosin were found in pigs fed 50 and 40 mg/kg, respectively, in the diet, even with zero withdrawal time. Residues of tylosin of 0.06 mg/kg and below were detected in liver and kidney from pigs fed 200 or 400 mg/kg and slaughtered within 3 h after the last feeding.  相似文献   

20.
Abstract

To investigate the activity of free cadmium (Cd2+), copper (Cu2+), lead (Pb2+), and zinc (Zn2+) ions and analyze their dependence on pH and other soil properties, ten contaminated soils were sampled and analyzed for total contents of Cd, Cu, Pb, and Zn (CdT, CuT, PbT, and ZnT, respectively), 0.43 MHNO3‐extractable Cd, Cu, Pb, and Zn (CdN, CuN, PbN, and ZnN, respectively), pH, dissolved organic matter (DOC), cation exchange capacity (CEC), ammonium oxalate extractable aluminum (Al) and iron (Fe), and dissolved calcium [Ca2+]. The activity of free Pb2+, Cd2+, Cu2+, and Zn2+ ions in soil solutions was determined using Donnan equilibrium/graphite furnace atomic absorption (DE/GFAA). The solubility of Cd in soils varied from 0.16 to 0.94 μg L‐1, Cu from 3.43 to 7.42 μg L‐1, Pb from 1.23 to 5.8 μg L‐1, and Zn from 24.5 to 34.3 μg L‐. In saturation soil extracts, the activity of free Cd2+ ions constituted 42 to 82% of the dissolved fraction, for Cu2+the range was 0.1 to 7.8%, for Pb2+ 0.1 to 5.1% and for Zn2+2 to 72%. The principal species of Cd, Cu, Pb, and Zn in the soil solution is free metal ions and hydrolyzed ions. Soil pH displayed a pronounced effect on the activity of free Cd2+, Cu2t, Pb2+, and Zn2+ ions.  相似文献   

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