藏西北高寒牧区气候特征及草地退化原因分析

本文利用藏西北高寒牧区9个气象站1971~2005年共35年的观测资料以及现代气候统计方法,分析了该区域与牧草长势相关的温度、降水、蒸发量等气象因子气候变化特征。分析表明,近35年来,藏西北高寒牧区平均温度、降水量的变化趋势为逐年增加,蒸发量逐年减小;各季节的变化与年变化趋势大致相同;藏西北高寒牧区两大区域,阿里地区的北部和那曲地区的气候特征存在明显差异;从牧草生长最重要的热量和水分条件来看,阿里牧区的气候变化特征朝着干热方向发展,对牧草的生长有不利影响,而那曲牧区气候变化特征为暖湿型,有利于牧草生长。然而,通过对整个藏西北高寒牧区牧草的研究表明,无论是阿里地区还是那曲地区,牧草都呈现出了退化趋势,导致草地退化的主要因素,除自然天气气候因素外,人类活动不可忽视。     

保护性耕作对蚕豆根际土壤微生物数量和酶活性的影响

为明确保护性耕作对蚕豆根际土壤酶活性、微生物的影响,本研究采用传统耕作(Traditional tillage,T)、垄作(Ridge tillage,R)、传统耕作+半量秸秆覆盖(Traditional tillage+Half amount of straw mulching,TS_1)、垄作+半量秸秆覆盖(Ridge tillage+Half amount of straw mulching,RS_1)、传统耕作+全量秸秆覆盖(Traditional tillage+Whole amount of straw mulching,TS_2)、垄作+全量秸秆覆盖(Ridge tillage+Whole amount of straw mulching,RS_2)6个不同处理,研究保护性耕作对蚕豆土壤微生物(细菌、真菌、放线菌)、酶活性(多酚氧化酶、转化酶、酸性磷酸酶)的影响以及它们之间的相关关系,从而为蚕豆生产实践中选择合理的耕作方式奠定科学基础。试验表明:(1)以T为对照,RS_2、TS_2、RS_1、TS_1、R均能在不同程度上提高细菌、真菌、放线菌的数量,其中RS_2效果最为明显。RS_2处理下根际土壤细菌在苗期、分枝期、开花期、结荚期、成熟期较T处理分别提高525.00%、132.55%、294.44%、23.85%、175.00%,真菌较T处理分别提高27.00%、69.39%、156.41%、48.09%、79.55%,放线菌较T处理分别提高138.01%、178.26%、134.29%、100.23%、130.36%;(2)垄作和秸秆覆盖均能提高土壤各种酶的活性,其中RS_2效果最显著。RS_2处理下根际土壤多酚氧化酶在苗期、分枝期、开花期、结荚期、成熟期较T处理分别提高38.34%、43.24%、1.44%、48.96%、123.89%,转化酶较T处理分别提高79.13%、99.66%、50.95%、24.06%、63.00%,酸性磷酸酶较T处理分别提高26.32%、22.65%、25.32%、21.81%、22.38%。(3)土壤微生物数量与土壤酶均呈正相关,其中细菌、放线菌与酸性磷酸酶、转化酶、多酚氧化酶均呈极显著正相关,真菌与酸性磷酸酶、转化酶呈极显著正相关。     

高寒草甸退化对土壤电导率变化影响的研究

土壤电导率是表征土壤水溶性盐的一个重要指标,可反映土壤盐渍化程度.为了研究高寒草甸退化对土壤电导率的影响,以三江源区未退化高寒草甸和退化高寒草甸为研究对象,系统分析了退化高寒草甸的植被特征和土壤特征与土壤电导率的相互关系.结果表明:高寒草甸退化会对土壤电导率产生显著负影响,且土壤电导率与评价高寒草甸的退化指标植被盖度、...     

异噁草酮对土壤微生物和土壤酶活性的影响

本试验检测了异噁草酮处理土壤后土壤中微生物群落数量和土壤酶活性变化,目的在于研究异噁草酮对土壤微生态产生的影响。结果表明:土壤中异噁草酮有效成分浓度为200、500μg/kg和700μg/kg时,促进土壤中细菌和真菌数量增长,该数量在处理7d之内就会明显变化,并且此影响随异噁草酮使用浓度的提高而增强,但异噁草酮对放线菌的数量无显著影响。施用异噁草酮后,土壤酶活性反应程度由高到低的顺序为:转化酶多酚氧化酶过氧化氢酶。本研究中异噁草酮施入土壤后,除对多酚氧化酶有明显抑制作用,且该抑制作用在短时间内可恢复外,对土壤微生物数量和土壤酶活性都有促进作用。     

阴山山脉典型森林植被土壤酶活性与微生物数量的研究

以阴山山脉6种典型森林植被土壤作为研究对象,利用传统稀释涂布平板法对微生物数量计数,并对土壤脲酶、亚硝酸还原酶和羟胺还原酶活性进行测定,探究其相关性。结果表明:不同植被的土壤酶活性和土壤微生物数量均呈显著差异性。脲酶活性中虎榛子最高,为84.90mgNH_3-N/g干土·24h;亚硝酸还原酶活性中白桦最高,为8.82mgNO_2-N/g干土·24h;羟胺还原酶活性中为杜松最高,是10.56mgNH_2OH/g土·5h。土壤微生物数量上都表现为细菌>固氮菌>真菌,均为虎榛子最高。相关性分析表明,土壤脲酶活性与三种微生物数量都呈极显著正相关(P<0.01),羟胺还原酶活性与细菌和固氮菌呈极显著正相关(P<0.01),与真菌呈显著正相关(P<0.05)。总体研究结果证明:在阴山山脉森林土壤生态系统中,除真菌数量外,酶活性、细菌和固氮菌数量表现为落叶阔叶林>常绿针叶林,落叶阔叶灌丛>常绿针叶灌丛,落叶阔叶疏林<常绿针叶疏林,植被类型对土壤酶活性和土壤微生物数量的影响很大。     

东祁连山河谷高寒草地植被群落特征及其与土壤性状的关系

为探究东祁连山河谷高寒草地植被群落特征与土壤性状的关系,根据研究区河谷地形地貌及河谷高寒草地分布特征,选取了分布在河谷山地阳坡上部和下部、河谷山地阴坡上部和下部及河谷水平阶地的5类不同植被类型的高寒草地为研究对象。研究草地植被群落和土壤性状特征及相关关系。结果表明:河谷中不同坡向、坡位高寒草地植被群落优势种不同,河谷阳坡高寒草地以嵩草属植物为主,阴坡以蓼属植物为主;阴坡植被总盖度高,阳坡低;河谷阴坡下部草层高度最高,而水平阶地最小;植被群落总科数、总属数和总种数均表现为坡下部高于上部,阴坡高于阳坡;地上生物量依次为:阴坡下部>阳坡上部>阴坡上部>阳坡下部>水平阶地;0~60 cm土层地下生物量依次为:阴坡下部>阳坡下部>阴坡上部>水平阶地>阳坡上部。不同高寒草地土壤性状之间有显著差异(P<0.05)。相关分析表明,土壤含水量、容重、孔隙度和全氮等指标与植被总盖度、地上生物量、总科数、草地平均高度有显著的相关关系。可见,研究区河谷高寒草地植被与土壤之间的影响主要表现为土壤含水量、容重、孔隙度和全氮与植被总盖度、地上生物量、总科数、草地平均高度间的相互作用。     

不同轮作方式对马铃薯土壤酶活性及微生物数量的影响

在连续种植2年马铃薯的土壤上进行不同轮作方式田间试验,探讨轮作方式对马铃薯土壤酶活性及土壤微生物数量的影响。试验结果表明:与对照(裸地)相比,小麦-豌豆-马铃薯轮作时土壤过氧化氢酶活性有增加的趋势;豌豆-马铃薯-豌豆轮作条件下,土壤的蔗糖酶活性提高,且在马铃薯成熟期提高幅度最大,为47.95%。轮作条件下土壤多酚氧化酶活性低于连作;轮作方式不同,土壤脲酶活性变化明显,在马铃薯块茎膨大期,豌豆-马铃薯-豌豆轮作方式的土壤脲酶活性比小麦-马铃薯-小麦高14.73%。马铃薯块茎膨大期根区土壤微生物数量测定结果显示:随着连作年限的增加,细菌数量及微生物总量降低,真菌数量升高了54.66%;小麦-豌豆-马铃薯轮作后,土壤中的细菌、放线菌数量最高,分别为6.40×106CFU·g-1和2.22×106CFU·g-1。     

丁草胺对土壤微生物数量和酶活性的影响

在模拟土壤生态系统中研究了丁草胺对土壤微生物数量和酶活性的影响。试验表明,低浓度(2 mg/kg)和中等浓度(4 mg/kg)丁草胺对微生物数量影响不大;而高浓度(10 mg/kg)处理则有明显抑制效应,但在21 d后也基本恢复到对照水平。丁草胺对土壤酸性磷酸酶、碱性磷酸酶、脲酶、蔗糖酶均产生了一定的抑制作用,并随浓度升高而增强,随着时间的延长,抑制作用逐渐消失,酶活性恢复至对照水平。丁草胺对土壤过氧化氢酶的影响与其他酶不同,表现出一定的刺激作用。     

土壤干旱对两品种小麦根际土壤微生物群落组成和酶活性的影响

采用双因素随机试验,在小麦孕穗期、灌浆期和成熟期研究了土壤干旱对两品种小麦根际土壤微生物丰度、多样性及4种酶活性(蔗糖酶、碱性磷酸酶、脲酶和脱氢酶)的影响。试验设4个处理,即分别在土壤干旱和正常水分下种植小麦"矮抗58"(P1)和"泛麦8号"(P2)。结果表明:与正常水分处理(种植P1和P2)相比,孕穗期,土壤干旱处理下小麦P1和P2根际土中普通细菌、革兰氏阴性细菌的丰度显著降低了11.3%和6.9%、8.4%和8.2%;灌浆期,干旱处理下小麦P1和P2根际土中丛枝菌根真菌的丰度明显下降了34.3%和21.8%;成熟期,干旱处理下小麦P1和P2根际土中革兰氏阳性细菌、真菌的丰度显著降低30.9%和8.6%、34.1%和17.3%。土壤干旱对微生物多样性无显著影响,却显著降低了孕穗期和灌浆期的碱性磷酸酶、脱氢酶活性和灌浆期的蔗糖酶活性,提高了成熟期的蔗糖酶活性。"矮抗58"比"泛麦8号"根际微生物多样性更高,但孕穗期其蔗糖酶活性更低。干旱与品种的交互作用对微生物各类群的丰度、多样性和4种酶活性的影响均不显著。综上,土壤干旱主要抑制微生物丰度,而品种间根际微生物多样性差异明显,干旱和品种均...     

高寒草地主要类型土壤因子特征及对地上生物量的影响

以新疆巴音布鲁克高寒草地五种主要草地类型的实测数据为依据,探讨了土壤因子随环境变化的特点及其对地上生物量之间的影响。结果表明:沼泽高寒草甸土壤含水量最大,有机质和速效N、P、K的含量都最高。高寒草原土壤含水量最小,有机质和速效养分的含量最低。土壤含水量与速N存在显著正相关,速P与速N和速K之间分别存在显著正相关,速K和有机质存在显著正相关。土壤含水量和速N含量是影响地上生物量的主要土壤因子,回归方程分别为Y=379.954X+28.238(F=12.562,P<0.05)和Y=0.864X-122.874(F=21.352,P<0.05)。     

氮添加对天山高寒草原土壤酶活性和酶化学计量特征的影响

为探究氮添加对高寒草原生态系统土壤酶活性的影响,于2018年在中国科学院巴音布鲁克草原生态系统研究站,选择4个氮添加水平(对照,N0,0 kg·hm^-2·a^-1;低氮,N1,10 kg·hm^-2·a^-1;中氮,N3,30 kg·hm^-2·a^-1;高氮,N9,90 kg·hm^-2·a^-1),开展土壤酶活性对氮添加响应的研究,分析土壤酶活性对氮添加的响应特点,土壤酶化学计量比以及土壤酶活性与土壤环境因子的关系。结果表明:与对照相比,氮添加在N3水平显著增加β-1,4葡萄糖苷酶(βG)、β-D-纤维二糖水解酶(CBH)和β-1,4木糖苷酶(βX)酶活性(P<0.05),N1和N3水平显著增加碱性磷酸酶(AKP)活性(P<0.05),N3水平显著降低多酚氧化酶(PPO)活性(P<0.05),氮添加对亮氨酸氨基肽酶(LAP)活性影响不显著,N3水平下显著增加N-乙酰-β-D氨基葡萄糖苷酶(NAG)活性(P<0.05)。相关分析表明,8种土壤酶活性均与土壤有机碳(SOC、NAG除外)和总磷(TP)显著相关,与土壤总氮(TN)不相关。研究区土壤酶活性C∶N∶P化学计量比为1∶1∶1.2,与全球生态系统的土壤酶活性C∶N∶P的比值1∶1∶1相偏离,表明该研究区土壤微生物生长受磷素限制。冗余分析(RDA)进一步揭示出土壤有机碳和土壤全磷含量是影响土壤酶活性的主要因子。     

氮添加对天山高寒草原土壤酶活性和酶化学计量特征的影响

为探究氮添加对高寒草原生态系统土壤酶活性的影响,于2018年在中国科学院巴音布鲁克草原生态系统研究站,选择4个氮添加水平（对照,N0,0 kg·hm^-2·a^-1;低氮,N1,10 kg·hm-2·a^-1;中氮,N3,30 kg·hm^-2·a^-1;高氮,N9,90 kg·hm^-2·a^-1）,开展土壤酶活性对氮添加响应的研究,分析土壤酶活性对氮添加的响应特点,土壤酶化学计量比以及土壤酶活性与土壤环境因子的关系。结果表明：与对照相比,氮添加在N3水平显著增加β-1,4葡萄糖苷酶（βG）、β-D-纤维二糖水解酶（CBH）和β-1,4木糖苷酶（βX）酶活性（P < 0.05）,N1和N3水平显著增加碱性磷酸酶（AKP）活性（P < 0.05）,N3水平显著降低多酚氧化酶（PPO）活性（P < 0.05）,氮添加对亮氨酸氨基肽酶（LAP）活性影响不显著,N3水平下显著增加N-乙酰-β-D氨基葡萄糖苷酶（NAG）活性（P < 0.05）。相关分析表明,8种土壤酶活性均与土壤有机碳（SOC、NAG除外）和总磷（TP）显著相关,与土壤总氮（TN）不相关。研究区土壤酶活性C∶N∶P化学计量比为1∶1∶1.2,与全球生态系统的土壤酶活性C∶N∶P的比值1∶1∶1相偏离,表明该研究区土壤微生物生长受磷素限制。冗余分析（RDA）进一步揭示出土壤有机碳和土壤全磷含量是影响土壤酶活性的主要因子。     

Effects of freezing intensity on soil solution nitrogen and microbial biomass nitrogen in an alpine grassland ecosystem on the Tibetan Plateau,China

The change of freeze-thaw pattern of the Tibetan Plateau under climate warming is bound to have a profound impact on the soil process of alpine grassland ecosystem;however,the research on the impact of the freeze-thaw action on nitrogen processes of the alpine grassland ecosystem on the Tibetan Plateau has not yet attracted much attention.In this study,the impact of the freezing strength on the soil nitrogen components of alpine grassland on the Tibetan Plateau was studied through laboratory freeze-thaw simulation experiments.The 0–10 cm topsoil was collected from the alpine marsh meadow and alpine meadow in the permafrost region of Beilu River.In the experiment,the soil samples were cultivated at –10°C,–7°C,–5°C,–3°C and –1°C,respectively for three days and then thawed at 2°C for one day.The results showed that after the freeze-thaw process,the soil microbial biomass nitrogen significantly decreased while the dissolved organic nitrogen and inorganic nitrogen significantly increased.When the freezing temperature was below –7°C,there was no significant difference between the content of nitrogen components,which implied a change of each nitrogen component might have a response threshold toward the freezing temperature.As the freeze-thaw process can lead to the risk of nitrogen loss in the alpine grassland ecosystem,more attention should be paid to the response of the soil nitrogen cycle of alpine grasslands on the Tibetan Plateau to the freeze-thaw process.     

异噁唑草酮对玉米根际土壤微生物量碳、氮和酶活性的影响

为明确异噁唑草酮对玉米根际土壤微生物碳、氮及酶活性的影响, 采用田间试验的方法, 以1倍、5倍和10倍田间推荐剂量为供试除草剂剂量, 测定了异噁唑草酮土壤封闭处理对玉米根际土壤微生物量碳、氮及土壤脲酶、过氧化氢酶、蔗糖酶、脱氢酶和中性磷酸酶活性的影响。结果表明:推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮含量无显著影响, 5倍和10倍推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮含量具有抑制作用。推荐剂量的异噁唑草酮对玉米根际土壤脲酶、过氧化氢酶和蔗糖酶影响较小, 5倍和10倍推荐剂量的异噁唑草酮对其具有明显的抑制作用。异噁唑草酮对土壤脱氢酶活性具有抑制作用, 且施用剂量越高, 抑制作用越强。异噁唑草酮对土壤中性磷酸酶活性的影响表现为前期促进, 后期抑制, 且施用剂量越大, 促进或抑制作用越强。研究表明:推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮及土壤脲酶、过氧化氢酶和蔗糖酶活性的影响较小, 但对土壤脱氢酶、中性磷酸酶活性有影响。     

Effects of fencing on vegetation and soil restoration in a degraded alkaline grassland in northeast China

In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent（DSE）/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application.     

CO_2,CH_4 and N_2O flux changes in degraded grassland soil of Inner Mongolia,China

The main purpose of this study was to explore the dynamic changes of greenhouse gas(GHG)from grasslands under different degradation levels during the growing seasons of Inner Mongolia, China.Grassland degradation is associated with the dynamics of GHG fluxes, e.g., CO_2, CH_4 and N_2O fluxes. As one of the global ecological environmental problems, grassland degradation has changed the vegetation productivity as well as the accumulation and decomposition rates of soil organic matter and thus will influence the carbon and nitrogen cycles of ecosystems, which will affect the GHG fluxes between grassland ecosystems and the atmosphere. Therefore, it is necessary to explore how the exchanges of CO_2,CH_4 and N_2O fluxes between soil and atmosphere are influenced by the grassland degradation. We measured the fluxes of CO_2, CH_4 and N_2O in lightly degraded, moderately degraded and severely degraded grasslands in Inner Mongolia of China during the growing seasons from July to September in 2013 and 2014. The typical semi-arid grassland of Inner Mongolia plays a role as the source of atmospheric CO_2 and N_2O and the sink for CH_4. Compared with CO_2 fluxes, N_2O and CH_4 fluxes were relatively low. The exchange of CO_2, N_2O and CH_4 fluxes between the grassland soil and the atmosphere may exclusively depend on the net exchange rate of CO_2 in semi-arid grasslands. The greenhouse gases showed a clear seasonal pattern, with the CO_2 fluxes of –33.63–386.36 mg/(m·h), CH_4 uptake fluxes of 0.113–0.023 mg/(m·h) and N_2O fluxes of –1.68–19.90 μg/(m·h). Grassland degradation significantly influenced CH_4 uptake but had no significant influence on CO_2 and N_2O emissions. Soil moisture and temperature were positively correlated with CO_2 emissions but had no significant effect on N_2O fluxes.Soil moisture may be the primary driving factor for CH_4 uptake. The research results can be in help to better understand the impact of grassland degradation on the ecological environment.     

保护性耕作方式对土壤微生物生理类群和酶活性的影响

通过设置在甘肃省定西市安定区李家堡乡的田间定位试验,研究了不同耕作方式下（NTS、TS、NT、T）土壤微生物生理类群数量和酶活性及其相关性。结果表明：与传统耕作（T）相比,保护性耕作方式（NTS、TS、NT）能显著增加土壤微生物生理类群数量,增强酶活性。不同的保护性耕作方式下,土壤微生物生理类群数量和酶活性存在显著差异...     

Artificial root exudates and soil organic carbon mineralization in a degraded sandy grassland in northern China

Plant root exudates contain various organic and inorganic components that include glucose, citric and oxalic acid. These components affect rhizosphere microbial and microfaunal activities, but the mechanisms are not fully known. Studies concerned from degraded grassland ecosystems with low soil carbon（C） contents are rare, in spite of the global distribution of grasslands in need of restoration. All these have a high potential for carbon sequestration, with a reduced carbon content due to overutilization. An exudate component that rapidly decomposes will increase soil respiration and CO2 emission, while a component that reduces decomposition of native soil carbon can reduce CO2 emission and actually help sequestering carbon in soil. Therefore, to investigate root exudate effects on rhizosphere activity, citric acid, glucose and oxalic acid（0.6 g C/kg dry soil） were added to soils from three biotopes（grassland, fixed dune and mobile dune） located in Naiman, Horqin Sandy Land, Inner Mongolia, China） and subjected to a 24-day incubation experiment together with a control. The soils were also analyzed for general soil properties. The results show that total respiration without exudate addition was highest in grassland soil, intermediate in fixed dune and lowest in mobile dune soil. However, the proportion of native soil carbon mineralized was highest in mobile dune soil, reflecting the low C/N ratio found there. The exudate effects on CO2-C emissions and other variables differed somewhat between biotopes, but total respiration（including that from the added substrates） was significantly increased in all combinations compared with the control, except for oxalic acid addition to mobile dune soil, which reduced CO2-C emissions from native soil carbon. A small but statistically significant increase in pH by the exudate additions in grassland and fixed dune soil was observed, but there was a major decrease from acid additions to mobile dune soil. In contrast, electrical conductivity decreased in grassland     

那曲高寒退化草原有毒杂草控制技术研究

采用两项国家发明专利产品"灭狼毒"、"灭棘豆",对狼毒、棘豆占优势的那曲退化草原进行有毒杂草防除试验,以探求防除最佳时间、最佳浓度,确定"灭狼毒"、"灭棘豆"使用的技术规范。并通过比较有毒杂草密度、多度、盖度、生物量等指标以及其他伴生种的群落学特征在药物喷洒前后的变化,得到如下结果:(1)喷洒1年后狼毒、棘豆的密度和生物量显著下降;(2)在最佳时间和最佳药量喷洒的情况下,有毒杂草的死亡率至少在80%以上;(3)喷药前后物种组成和物种丰富度的变化不大,但主要物种的相对多度或相对数量显著降低,同时有毒杂草的植株矮化。根据试验结果得到技术规程如下:"灭狼毒"的最佳喷药时间为6月下旬—7月上旬,即在狼毒的盛花期。"灭棘豆"的最佳喷药时间在7月上旬—7月中旬,即棘豆的盛花期。最佳药物使用量:"灭狼毒"的用量为1 050 mL/hm2,"灭棘豆"的用量为1 200 mL/hm2。喷药时应选择晴朗、小风(风力2~3级)的天气,使用原药直接超低量喷洒,不用加水稀释。