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1.
主要通过土柱模拟试验探究不同有机物料对渗滤液的盐分和可溶性有机碳（DOC）以及不同深度土壤盐分、有机质和微生物生物量碳氮的影响,设置有机硅功能肥（WO）、颗粒状有机物料（YP）、粉末状有机物料（GG）、颗粒状有机物料和粉末状有机物料各50%（YG）以及不添加有机物料（CK）共5个处理。结果表明,有机物料的添加提高了渗滤液的EC值及水溶性Ca2+、Mg2+和Na+含量,YP处理的渗滤液盐基离子含量最高,而WO处理的渗滤液中DOC含量最低;与CK处理相比,WO处理显著提高各深度土层的水溶性Ca2+、Mg2+和K+含量,显著降低各深度土层的pH、交换性Na+、碱化度（ESP）和0—20 cm土层的水溶性Na+和钠吸附比（SAR）,但其他有机物料的处理对pH、EC值和盐分等无显著影响;淋洗作用使表层土壤（0—20 cm）盐分向土壤深层移动,淋洗结束后,各处理的土壤EC值、水溶性总盐、交换性Na+和ESP随着土层深度的增加而升高;与CK处理相比,GG和YG处理显著提高0—20 cm土层的有机质含量,分别提高23.97%和20.53%。研究结果为有机物料的添加对盐碱地淋洗过程中盐分和有机质的变化提供了理论的数据参考。 相似文献
2.
民勤绿洲盐生草生境土壤盐分特征及离子组成 总被引：2，自引：0，他引：2
对民勤绿洲盐生草周围不同距离范围内的总体盐分状况、盐分离子组成及离子之间的相关性进行了研究。结果表明,盐生草具有一定的聚盐作用,在其周围形成了一定的"盐岛"效应。在距盐生草0-60 cm范围内,土壤剖面中的土壤盐渍化程度随土层的加深而加重,土壤阴离子主要有Cl-和SO42-,阳离子主要有Na+和Ca2+,土壤盐分主要是氯化钠、氯化钙、硫酸钠和硫酸钙,其次是氯化镁和硫酸镁。其中在盐生草周围0-40 cm范围内,垂直剖面0-20 cm土层土壤全盐含量为0.98~1.52 g/kg,属于非盐渍化土壤,20-40 cm土层土壤全盐含量达到了2.25~2.30 g/kg,属于轻度盐渍化土壤,40-60 cm土层土壤全盐含量达到了3.10~3.16 g/kg,属中度盐渍化;在距盐生草60 cm处,垂直剖面0-40 cm土层土壤全盐含量为0.83~1.86 g/kg,属非盐渍化,40-60 cm土层土壤全盐含量达到了2.43 g/kg,属轻度盐渍化。除HCO3-外,土壤盐分含量与各盐分离子之间均呈极显著正相关。 相似文献
3.
起垄和施肥对冷浸田土壤氧化还原状况的影响 总被引：4，自引：1，他引：3
通过起垄和施肥试验, 研究不同措施对冷浸田土壤氧化还原状况的影响, 以期为冷浸田改良提供数据参考。结果表明, 冷浸田土壤氧化还原电位介于 48.5~ 198.0 mV之间, 远低于正常稻田(450~700 mV)。起垄使0~5 cm土层氧化还原电位有升高趋势, 但使>5 cm土层土壤氧化还原电位降低。冷浸田还原性物质总量变化范围为5.7~15.6 cmol·kg-1(起垄试验)和7.7~16.0 cmol·kg-1(施肥试验), 起垄在短期内会提高土壤还原性物质总量, 增施钾肥、锌肥和硅肥会降低土壤还原性物质总量, 而磷肥用量对土壤还原性物质基本无影响。0~25 cm和25~50 cm土层土壤Fe2+含量平均为3 388.92 mg·kg-1和3 356.39 mg·kg-1; 起垄60 d后, 土壤Fe2+含量随着起垄高度增加而逐渐降低; 与不施肥(CK)、氮磷钾(NPK)处理相比, 施钾量增加20%(NPK2)、增加硅肥(NPK+Si)和增加锌肥(NPK+Zn)可以大幅度降低土壤Fe2+含量; 0~25 cm土层土壤Fe2+含量高于25~50 cm土层。 起垄和施肥使冷浸田土壤Mn2+含量先降低后升高。 相似文献
4.
为了实现内蒙古河套灌区盐碱土壤快速改良和构建淡化和肥沃的耕层,将脱硫石膏分别与腐植酸(改良剂GF)、糠醛渣(改良剂GH)按2∶3的质量比配制两种钙基型土壤改良剂。采用田间小区试验,以不施用改良剂为对照(CK),研究了两种改良剂不同施用量处理(15、30和45 t/hm2)对收获期土壤盐分离子、养分含量和向日葵产量的影响。结果表明:与CK相比,两种改良剂处理显著降低了0～40 cm土层的pH值和0～20 cm土层的钠吸附比,但20～40 cm土层全盐量有所增加,尤其是改良剂施用量为45 t/hm2的处理。两种改良剂处理均可显著提高0～20 cm土层有机质含量,改良剂GF可提高土壤有效磷和铵态氮含量,改良剂GH可提高土壤速效钾含量。向日葵产量也得到显著提高,主要与土壤pH值、有效磷及铵态氮含量显著相关,在同等施用量条件下,改良剂GF消减土壤盐碱障碍,提高土壤养分含量的效果明显优于改良剂GH,进而获得了较高的向日葵产量。综上所述,改良剂GF施用量为15 t/hm2的处理在短期内能够实现土壤盐碱土壤改良、培肥和增产的效果,可在内蒙古河套灌区及同类地区进行推广应用。 相似文献
5.
以黄土区云雾山典型草原为研究对象,分析4种干扰方式(封育、封育+施肥、封育+火烧和放牧)对土壤理化性质的影响。结果表明:(1)在0-50cm土层,封育、封育+施肥、封育+火烧地的土壤容重随土层深度的增加而增加,放牧地的土壤容重随土层深度的增加而减少。其中,在0-20cm土层,放牧显著高于其他3种干扰方式,封育+施肥显著低于其他3种干扰方式;(2)在0-50cm土层,4种干扰方式的土壤含水量随土层深度的增加而增加,依次为封育+火烧>封育+施肥>封育>放牧;(3)在0-50cm土层,4种干扰方式的土壤有机质、全氮和速效钾含量随土层深度的增加而减少;火烧地的全磷含量随土层深度增加而减少,其他3种干扰方式的全磷含量呈现先增加后减少的趋势。在0-30cm土层,4种干扰方式土壤养分(有机质、全氮、全磷和速效钾)含量为封育+施肥>封育+火烧>封育>放牧,且放牧会导致0-10cm所有养分含量显著降低(P<0.01)。(4)4种干扰方式,有机质与全氮、全磷和速效钾呈极显著的正相关关系(P<0.01)。 相似文献
6.
盐碱地盐分含量高,会对植物生长起抑制作用或直接造成危害,盐碱地的安全利用对保障粮食安全具有重大意义。为探讨化肥减量配施不同有机肥对盐碱地土壤性状及镉形态的影响变化特征,试验在化肥施用减量20%的基础上,设厩肥30000 kg/hm2(AM)、生物有机肥600 kg/hm2(BF)、厩肥30000 kg/hm2+生物有机肥600 kg/hm2(AM+BF)及化肥正常施用量(CK)4种施肥处理,研究不同有机肥配施对土壤性状、镉含量及形态的影响。结果表明:2020年,处理BF较CK土壤镉含量显著降低了16.99%;2021年,处理BF和AM与CK相比,土壤镉含量分别降低了14.06%和10.16%,且差异显著。2020年,与CK相比,处理BF、AM和AM+BF土壤有效态镉含量分别显著降低了67.44%、34.88%和60.47%;2021年,处理BF、AM和AM+BF与CK相比,有效态镉含量分别降低了66.67%、27.27%和51.52%,且差异显著。与CK相比,有机肥配施对土壤中镉形态的分配比例有明显影响,交换态镉降低19.34%～75.69%、有机结合态镉提高45.78%～135.22%、土壤pH提高1.06%～5.81%;阳离子交换量提高5.29%～29.11%、有机质含量提高4.35%～30.14%、土壤容重降低0.76%～9.09%、过氧化氢酶活性提高7.84%～56.02%、脲酶活性提高14.67%～29.07%、碱性磷酸酶活性提高16.54%～40.09%、微生物量碳提高8.02%～25.09%、微生物量氮提高12.28%～33.12%。综上,在盐碱土壤条件下,配施有机肥可改善土壤理化性状、生物学特性,促进土壤交换态镉向有机结合态镉的转化,达到降低土壤有效态镉的目的。 相似文献
7.
本文研究了土壤有机质和陪伴阴离子对黄棕壤、红壤和砖红壤吸附Zn2+的影响。结果表明:土壤有机质含量与吸附Zn2+的数量呈正相关;陪伴阴离子对土壤吸Zn2+量有显著的制约作用,土壤从ZnCl2溶液中吸附的Zn2+数量高于Zn(NO3)2的0.77-1.16倍;△pH值与吸Zn2+量呈直线关系。由解吸情况可以判明红壤胶体表面的高能吸附位占的比例明显大于黄棕壤或砖红壤。 相似文献
8.
探究弃渣与农田土不同混合比例下重构土体粒径特征和水文效应的差异,对于提高采石废弃地重构土体的结构稳定、水资源高效利用以及资源利用化具有重要意义。以采石场弃渣和农田土为重构基质,以0∶10(C1),3∶7(C2),5∶5(C3),7∶3(C4),10∶0(C5)体积比例混合,采用野外土柱模拟方法,探究不同配比下土壤粒径特征和水文效应的差异。结果表明:(1)不同配比下弃渣含量越高,砂粒比重越大、黏粒和粉粒比重越小,砂粒比重最大为61.50%,分散度、偏度、峰态等群体特征参数变化分别为降低、升高、升高,不均匀系数显著降低,曲率系数在1~3波动,分形维数呈不显著降低趋势,土体结构朝不稳定方向变化。(2)混合土壤弃渣含量增大会引起容重变大、毛管孔隙和总孔隙数量减少、非毛管孔隙数量增加等土壤孔隙方面以及田间持水、毛管持水、饱和持水三者下降等土壤持水性能方面的变化,同时,初始入渗、稳定入渗、平均入渗等速率变化以及累计入渗量基本呈增加趋势,稳渗用时呈波动式变化。不同配比下土壤入渗模型拟合R2≥0.856,RRMSE≤0.153,整体上模型拟合效果较好,灰色关联分析结果表明,C5入渗性能最好。(3)弃渣∶农田土以3∶7体积比例混合后的土壤在粒径结构和水文效应2个方面评价结果中表现最佳。[JP] 相似文献
9.
溶质类型与矿化度对半干旱盐渍化地区果园土壤水分有效性的影响 总被引：3，自引：0，他引：3
盐渍化土壤水分有效性是制约土地生产能力的关键因素之一。研究不同盐分类型及矿化度的盐溶液对土壤水分有效性的影响, 可为微咸水合理灌溉以及促进土壤生产潜力的发挥提供科学依据。本研究采用离心法在室内研究了脱水过程中灌溉水的溶质类型(NaCl和Na2SO4)与矿化度(0、1 g·L-1、3 g·L-1、5 g·L-1、10 g·L-1)对半干旱盐渍化地区果园土壤水分有效性的影响。结果表明: 不同矿化度的NaCl和Na2SO4处理均可使田间持水量、暂时萎蔫系数、永久萎蔫系数、迟效水和无效水较对照有所降低。不同矿化度的NaCl处理以及1 g·L-1的Na2SO4处理土壤全有效水和速效水都较对照增加, 3 g·L-1、5 g·L-1和10 g·L-1的Na2SO4处理土壤全有效水和速效水都较对照减小。不同矿化度的NaCl和Na2SO4处理均可使土壤通气孔隙和毛管孔隙相对减少, 非活性孔隙增大, 其中矿化度为5 g·L-1的NaCl和Na2SO4处理对其影响最为明显, 通气孔隙分别较对照减小16.8%和14.8%, 毛管孔隙分别较对照减小5.2%和6.5%, 非活性孔隙分别较对照增加15.7%和14.4%。NaCl对于土壤比水容量和毛管断裂的延迟效果比NaSO4明显。且土壤溶液盐分含量增加, 土壤持水能力下降、供水性能增加而土壤抗旱性降低。 相似文献
10.
鉴于日光温室和农田两种土地利用施肥和农艺措施的差异,研究由农田向日光温室转变后深层土壤磷素累积及分布,为评价磷素有效性及淋失状况,指导日光温室磷肥合理施用,降低磷素损失提供理论参考。对黄土高原东北部日光温室及农田磷肥投入和携出状况调查,同时,采集0～400 cm土层土壤剖面样品,测定土壤Olsen-P和CaCl2-P含量,比较两种土地利用方式下养分平衡及深层土壤剖面磷素的累积及分布状况。结果显示,日光温室磷肥年均投入量为897 kg/hm2,显著高于农田,磷盈余量平均为679 kg/hm2,为农田的10.9倍。日光温室0～20 cm土层土壤Olsen-P含量高达400.5 mg/kg,为农田对应土层的44倍;0～40、40～100、100～200、200～300、300～400和0～400 cm土层土壤剖面Olsen-P累积量分别为1637、443、277、378、258和2993 kg/hm2,显著高于农田对应土层累积量(41、54、122、174、163和554 kg/hm2);40 cm以下土层Olsen-P累积量占整个0～400 cm土层土壤剖面累积量的45.3%,磷素出现了明显的淋溶损失现象。土壤剖面各土层CaCl2 -P含量均随Olsen-P含量的增加而增加,二者表现为显著的正相关关系。结果表明,研究区由农田向日光温室转变显著增加了土壤磷素的累积及向深层土壤的淋溶损失。因此,日光温室降低磷肥投入,改善管理措施十分必要。 相似文献
11.
The immediate effect of low and high severity wildfires on the main soil properties, as well as their short‐ and medium‐term evolution under field conditions, was examined. The study was performed with three pine forest soils (two Leptosols and one Humic Cambisol, developed over granite and basic schist, respectively), located in the Atlantic humid temperate zone (Galicia, NW Spain). Samples were collected from the A‐horizon (0–5 cm depth) of the burnt and the corresponding unburnt soils, immediately and 3, 6 and 12 months after the wildfires. Most properties analysed exhibit immediate fire‐induced changes and different evolution depending on fire severity and soil type. In general, immediately after the fire pH and soil properties related to nutrients availability increased and cation exchange capacity decreased, whereas properties related to soil organic matter content (C, N, Fe and Al oxides) had a variable effect depending mainly on the soil studied; all these modifications were accentuated by fire severity. These effects were attenuated in the short term in the soil affected by a low severity wildfire, but they lasted for at least 1 year in the soils affected by high severity wildfires, particularly in the Leptosols. The results showed the importance of the fire as a disturbance agent in the dynamic of nutrients and soil organic matter that is directly related with soil quality in the Galician forest ecosystems. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
12.
The effect of forest fire on soil enzyme activity of spruce (Picea balfouriana) forest in the eastern Qinghai-Tibetan Plateau was assessed. Six specific enzymes were chosen for investigation: invertase, acid phosphatase, proteinase, catalase, peroxidase and polyphenoloxidase. It was found that the activities of invertase and proteinase were reduced by burning, but the activities of acid phosphatase, polyphenoloxidase and peroxidase increased. Meanwhile, burning significantly (P < 0.05) resulted in the decrease of concentrations of available N and K of 0–20 cm depth layer soil, and significantly (P < 0.05) decreased concentrations of organic matter content, total N and P, as well as available N, P and K in soil at both 20–40 and 40–60 cm depths except for available P at 20–40 cm soil depth. These results illustrated that burning could influence the enzyme activities and chemical properties of soil not only of upper but also lower soil layers. Correlation analysis indicated that invertase activities in 0–20 cm depth layer soil were significantly positively correlated with organic matter, total N and P, as well as available N and P. Furthermore, all six enzymes studied were sensitive to fire disturbance, and thus could be used as indicators of soil quality. Our study also showed that soil enzyme activities were associated with soil depth, decreasing from top to bottom in both burned and unburned spruce forests. The distribution pattern of soil enzyme activities suggested that the rate of organic matter decomposition and nutrient cycling depended on soil depth, which had important structural and functional characteristics in nutrient cycling dynamics and implications in plantation nutrient management. The finding that burning effects on enzyme activities and soil properties between different soil layers were homogenized was attributed to the 8-years’ regeneration of forest after burning. 相似文献
13.
火干扰作为一种自然扰动现象,对土壤物理、化学、矿化和微生物等土壤性质产生一定影响.在河南具茨山国家级森林公园过火林地和草地,进行土壤样品(0～5和5～10 cm土层)采集,测定表征土壤渗透性和持水能力的指标,研究中度火干扰对不同土层土壤理化特性的短期影响.结果表明:中度火干扰造成草地和林地土壤表层(0 ～5 cm)的土壤密度、含水率和非毛管孔隙度显著下降(P＜0.05),但火烧前后,土壤5～ 10 cm层上述物理特性指标之间没有显著差异(P＞0.05);火烧后草地和林地土壤表层(0～5 cm)有机C和全N显著下降(P＜0.05),而土壤pH、全P和全K显著上升(P＜0.05),相似的现象出现在草地土壤5～10 cm层,火烧前后林地土壤5～ 10 cm层,各化学特性指标没有显著差异(P＞0.05).火烧使草地和林地土壤0～5cm层的土壤初渗率、稳渗率和平均入渗率均显著上升(P＜0.05),而对土壤5 ～10 cm层土壤各渗透特性指标没有显著影响(P＞0.05);火烧使草地和林地土壤0 ～～5 cm层土壤最大持水量和有效持水量均显著下降(P＜0.05),草地和林地最大持水量分别从未过火289.984和390.971t/hm2,下降到258.072和342.386 t/hm2.该研究为开展火烧迹地植被恢复、水土保持和森林经营管理措施的制定,提供科学依据. 相似文献
14.
不同火干扰强度对枫香次生林土壤理化性质的影响 总被引：1，自引：1，他引：0
火干扰是影响森林土壤生态系统结构与功能的重要因素之一。探讨火干扰后森林土壤理化性质的动态特征,为火后植被恢复以及森林可持续经营提供重要的理论指导。2014—2016年在湖南省株洲市枫香次生林内设置16块20 m×20 m样地进行试验,研究4种火干扰强度(对照、低强度、中强度、高强度火烧)后不同时间节点(火烧后3,30,180,360,720天)的枫香次生林的土壤容重(BD)、土壤斥水性(SWR)、有机质(SOM)、pH、全氮(TN)、全磷(TP)和全钾(TK)等指标。通过描述性统计、单因素方差分析和Fisher LSD检验研究了土壤性质在同一时间节点不同火干扰强度之间以及同一火干扰强度下不同时间节点间的显著性差异(p0.05)。结果表明:火干扰后各时间节点下,BD、SWR、pH、TK均随火强度增大而增加,而SOM和TP随火强度增大而降低,不同火干扰间TN均不存在显著性差异。同一时间节点内火干扰土壤与对照相比,低强度火干扰对BD、SWR、pH和SOM的影响不显著,中强度火对部分时间节点下的土壤理化性质有影响,而高强度火对其影响均比较显著。同一强度火干扰后,BD、SWR、pH在不同时间节点间存在显著性差异,BD、SWR、pH在火烧后3天显著增大,然后逐渐减少;BD在火后360天恢复到火烧前状态,而SWR、pH则需720天。SOM仅在高强度火烧后360,720天与其他时间节点间存在显著性差异;火干扰后,SOM与火烧前相比先减少,后逐渐上升,火后360天逐渐恢复到火烧前的水平并维持稳定。中、高强度火干扰后,时间节点跨度越大,TK的差异越显著,而TN和TP仅在高强度火烧后差异显著。研究发现火干扰强度和时间节点对7种土壤性质均有一定影响,其中高强度火干扰对土壤理化性质影响最大。火干扰后短期内引起地力衰退,影响林地土壤养分状况,对土壤生态系统产生重要影响,但随着时间推移,2年后土壤理化性质基本恢复到火烧前的水平。 相似文献
15.
《Land Degradation \u0026amp; Development》2017,28(3):1068-1077
The effects of fire and the conversion to vineyard on soil organic carbon (SOC), and soil aggregate size distribution and stability were studied in a forest of Iran. For this purpose, topsoil was sampled in an unburned area, a portion of the forest burned three years earlier, and a vineyard, all three contiguous and showing similar topographic features. In the burned forest, soil was sampled in areas undergone high, moderate, or low severity. Air‐dried soil samples were sieved to obtain four aggregate size classes, which were subsequently wet sieved. Soil aggregate distribution index, mean weight diameter, geometric mean diameter, and aggregate stability index were determined on both dry and wet specimens. No significant differences in SOC between burned and unburned forest were found, most probably because of the supply of charred biomass to soil, while in the vineyard thirty years of cultivation had removed half of initial SOC. Both severe fire and cultivation had decreased the stability of aggregates and the relative amount of the biggest ones (8 to 2‐cm diameter). However, aggregate stability was significantly lower in the vineyard than in the burned forest, which points out to a stronger impact of prolonged cultivation than a single fire, although severe. Cultivation and severe fire had decreased the proportion of C in macroaggregates, to the advantage of meso (1 to 0.25 mm) and micro (<0.25 mm) aggregates. A hierarchical cluster analysis of all investigated properties and indices demonstrated that cultivation and highly severe fire both were causes of soil degradation. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
16.
大兴安岭北部试验林火影响下土壤有机碳含量的时空变化 总被引：7，自引：0，他引：7
在大兴安岭北部寒温带针叶林地进行严密监控下的秋季野外林火点烧试验。通过样地网格布点和火烧前后对比监测,研究林火影响下土壤(0-10cm)有机碳含量的时空动态。结果显示,林火过后土壤有机碳含量变化的方向和程度因火烧强度和时间阶段而异,各阶段变化的空间格局与林火强度格局相一致。轻、中度火烧对土壤有机碳的即时影响不显著;经过第2年融雪季和雨季后,土壤有机碳含量有显著的小幅递增,平均增幅3.5%～4.2%;至火烧后第3年秋季显著回降。重度火烧后土壤有机碳含量有极显著的即时下降,平均降幅14.6%;经过第2年融雪季和雨季后,变化呈两极分化,大部分点位持续大幅度降低(平均降幅25.4%),个别点位大幅度增高(增幅78.7%);至火烧后第3年秋季,两极分化进一步加剧,降低点位有机碳含量平均降幅39.9%,个别增高点位有机碳含量增幅却高达107.2%。轻、中度火烧土壤有机碳增高的主导因素是植被和枯落物层有机颗粒物、炭化颗粒物以及半腐烂死细根混入等;而其后期回落则主要与表土层塌缩有关。重度火烧土壤有机碳降低的主导因素是表层有机碳燃烧损失和高温挥发损失,以及后期的侵蚀损失等;其后期局部区域大幅增高,主要是洼地有机碳堆积所致。另外,表土塌缩、烧毁、侵蚀均导致采样深度下延,下层土壤对含量指标的"稀释效应"是土壤有机碳含量变化的重要叠加因素。 相似文献
17.
In addition to its direct impact on soil physical and chemical soil properties, fire produces a sudden change in plant cover. The post-fire impact of falling raindrops on unprotected soil surfaces is a major cause of detachment of aggregates, physical degradation and erosion of soils. The aim of this work was to analyse the effects of burning intensity and rain under factor-controlled conditions using unaltered soil samples. Assessed variables were soil organic carbon, aggregate stability and water repellency (0–1 cm mineral soil), as well as soil surface compaction and hydraulic conductivity. Unaltered topsoil cores were obtained in a mature Mediterranean gorse shrubland. We applied two successive treatments: burning (unburned, low and high burning levels) and rain (77 mm/h). The soil properties studied were scarcely affected by burning. However, soils showed high vulnerability to raindrop impact: a) aggregate stability and organic carbon were not significantly affected by burning; b) low intensity burning increased the frequency of samples with moderate water repellency, whereas unburned together with high burning showed more cases of low and extreme water repellency; c) the rain treatment produced a significant decrease in hydraulic conductivity although this response was independent of burning level; d) the highest reduction in hydraulic conductivity was observed in the samples with highest values prior to the rain treatment, and this was related to the highest organic carbon contents, and e) the reduction in hydraulic conductivity could be explained by the development of a thin and friable surface crust, although the cone penetrometer was not sensitive enough to detect this observed phenomenon. 相似文献
18.
This study examined variations in soil organic C content and the activity of acid phosphatase, α-glucosidase, phenol oxidase, chitinase, and l-glutaminase in ultisols of burned and unburned areas in Quercus-dominated forests in Ohio, USA. The low intensity, prescribed fires were conducted in April 2001, with temperature 10 cm above the forest floor averaging 160-240 °C. Sampling was conducted throughout the six month growing season (May-October) of 2003, two years after the fire. Organic C content in these ultisols varied between 20 and 30 g C/kg soil, and varied little through the growing season, except for a late season increase to ∼32 g C/kg soil in the burned areas. When enzyme activity was expressed per unit soil organic C, there was no statistically significant variation among sample dates in soil enzyme activity except l-glutaminase, which demonstrated a distinct maximum in activity in spring. Non-metric multidimensional scaling (NMS) ordination resulted in no clear separation of burned and unburned sample areas based on soil organic C and enzyme activity. When the growing season was divided into three segments (early spring, late spring/early summer, and late summer/early autumn), there was again a lack of separation between burned and unburned areas in the earlier two segments, whereas in the late summer/early autumn segment the burned and unburned areas were clearly separated on the basis of differences in soil organic C and l-glutaminase activity. As environmental factors (e.g. soil temperature, moisture) and substrate availability do not vary in parallel through the growing season in this region, seasonal patterns often differ among enzyme systems based on their predominant control mechanism. Sampling time during the growing season appears to have little effect on holistic judgments of fire effects based on soil enzymes, except under restrictive conditions. 相似文献
19.
Soil macroaggregation in relation to soil organic matter (SOM) and calcium carbonate (CaCO3) content was studied, before and after experimental fires of different intensities, in two environments (under canopy and on bare soil). In 1995, two experimental fire treatments, based on the addition of different biomass amounts, were applied on a set of nine plots at the Permanent Field Station of La Concordia (Valencia, Spain). Three plots were burned with high intensity fire (T1), three with moderate intensity (T2) and three plots were left unburned to be used as control treatment (T3). 相似文献
20.
大兴安岭天然针叶林不同强度火干扰10年后土壤有机碳含量变化 总被引：2，自引：0，他引：2
在大兴安岭呼中国家级自然保护区2000年的火烧迹地上,按植被组合类型(杜香-兴安落叶松林和草类-兴安落叶松林)和火干扰强度不同选择样区进行采样,对土壤有机碳含量变化进行研究。结果表明:火干扰10年后,各样区有机层的有机碳含量均随深度的增加而减少,不同强度火干扰造成各样区各有机层有机碳含量变化不一;矿质层除了重度火干扰杜香-兴安落叶松植被下土壤以外,土壤有机碳均随深度的增加而减小,表层土壤有机碳含量最高;2种植被类型下,矿质土壤的A层和B层有机碳含量随火烧强度的增强而减小,说明在寒温带针叶林地区不同强度火干扰10年后,土壤有机碳并未恢复到火烧之前水平;不同强度火干扰杜香-兴安落叶松样区的有机层和矿质层的有机碳含量呈现相同的变化趋势,均为重度火干扰样区<轻度火干扰样区,反映了有机层对矿质层有机碳的补给作用;不同强度火干扰草类-兴安落叶松样区的有机层和矿质层的有机碳含量并未呈现规律性变化。 相似文献