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1.
以161个公里网格样地为基础,对尖峰岭热带雨林原始林和不同采伐方式(径级择伐和皆伐)下天然更新的次生林凋落物储量、持水量、持水率和吸水速率进行了研究。结果表明,原始林、径级择伐林和皆伐林的凋落物储量分别为6.42,6.29和6.66t/hm2;最大持水量分别为9.55,10.49和11.17t/hm2。3类型森林凋落物最大持水率大小依次为皆伐林(169.2%)>径级择伐林(168.0%)>原始林(155.6%),经Kruskal—Wallis H检验表明,原始林、径级择伐林和皆伐林凋落物最大持水率间差异显著。凋落物持水量和凋落物持水率随着浸泡时间的增加符合W=alnt+b模型而变化,凋落物吸水速率随着浸泡时间的增加依W=at-b模型下降。 相似文献
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不同采集作业方式对森林景观生态的影响 总被引：5，自引：1，他引：5
通过研究人工林伐区不同采集作业方式对森林景观生态的影响,结果表明:皆伐对森林景观生态的影响大于择伐,带状皆伐的影响大于块状皆伐,伐区间隔排列的影响大于连续顺序排列,大面积皆伐的影响大于小面积皆伐;择伐对森林景观生态的影响随择伐强度的增大而增大,且径级择伐影响大于集约择伐;集材作业对森林景观生态的影响与集材方式有关,其影响由大到小依次为手扶拖拉机、手板车、土滑道、绞盘机和架空索道。随集运材道路网密度的增大,其影响也增大。进而提出减少采集作业对森林生态及景观生态影响的对策。 相似文献
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沼泽垦殖前后土壤呼吸与CH_4通量变化 总被引：6，自引：0，他引：6
湿地是陆地生态系统的重要组成部分,在碳的储存中起着重要作用。湿地垦殖后,在相同季节根层土壤温度明显高于沼泽湿地土壤,但垦殖后土壤有机碳、氮素含量明显降低,C:N比值减小,土壤呼吸通量增大,且具有季节性变化。垦殖8年的农田土壤,呼吸通量大于垦殖15年的农田土壤,弃耕后土壤有机碳含量及土壤呼吸强度有所增加,土壤呼吸通量与土壤温度呈显著正相关关系。沼泽湿地土壤为大气CH4的重要源,通量季节性变化明显,沼泽垦殖后农田土壤成为CH4的汇,不同垦殖年限土壤间CH4通量差异性不大。 相似文献
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采伐干扰对东北温带次生林土壤碳矿化和活性有机碳的影响 总被引：1，自引：0，他引：1
在黑龙江东部的张广才岭选择典型次生杂木林进行不同采伐处理,一个生长季后测定了土壤潜在碳矿化速率和活性有机碳含量.结果表明:在28℃条件下经过90d的培养,土壤潜在碳矿化速率和碳矿化总量在所测定的土层中(0-10 cm,10-20 cm,20-30 cm)均表现为:50%强度采伐>皆伐后农作>25%强度采伐≌对照>皆伐后造林的变化趋势,但各处理间差异不显著.土壤易氧化碳含量在3个土层50%强度采伐均显著高于对照.土壤微生物碳含量在0-10 cm和10-20 cm土层,50%强度采伐显著高于对照.在0-10 cm土层,皆伐后造林显著低于对照.水溶性有机碳含量在0-10 cm和10-20 cm土层,50%强度采伐显著高于对照,在20-30cm土层,皆伐后造林显著低于对照,这说明在东北温带次生林中,较大强度的择伐短期内可增加土壤活性有机碳含量.而皆伐后造林可导致土壤活性有机碳出现下降趋势. 相似文献
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高原湿地纳帕海4种湿地利用类型土壤养分和微生物特征研究 总被引：2，自引：0，他引：2
采用实地调查与In-situ取样技术及室内实验分析,对滇西北高原湿地纳帕海现存4种湿地利用类型土壤养分和微生物数量特征进行研究。结果表明:(1)在人为活动干扰下,湿地类型从原生沼泽向沼泽草甸、草甸和垦后湿地演替,土壤有机质和全氮含量呈现明显的衰减下降,其中有机质下降54.06g/kg,全氮下降1.96g/kg。(2)经F检验结果表明:4种湿地利用类型中土壤微生物总数存在显著差异,表现为沼泽草甸>草甸>垦后湿地>原生沼泽;土壤真菌和放线菌呈相同的变化趋势,为沼泽草甸>垦后湿地>草甸>原生沼泽;土壤养分和微生物数量变化均具有明显的空间层次现象,即随土层加深而降低,表聚性明显。(3)除原生沼泽之外的3种湿地利用类型中土壤微生物数量与有机质和全氮含量呈极显著正相关。(4)人为干扰加速纳帕海湿地的逆向演替进程,土壤养分与微生物特征的变化是对人为不同干扰类型与强度的响应。 相似文献
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不同经营措施对油松林枯落物持水性能的影响研究 总被引：3，自引：2，他引：1
为了评价不同经营措施对油松人工林枯落物持水能力的影响,通过带状皆伐、封禁抚育、孔状择伐、修枝抚育、引进灌木这5种措施,并以未封禁作为对照的实验方法,分别在抚育开始、抚育后2a、抚育后4a对枯落物的储量、最大含水量、自然含水量和有效拦蓄量进行了测定和评价。结果表明:(1)枯落物储量和持水性能随抚育时间的延长呈增加趋势。(2)不同经营措施下,抚育后2和4a的枯落物储量大小顺序均为:带状皆伐>封育恢复>孔状择伐>修枝抚育>引进灌木>未封禁枯落物最大含水量在抚育后1~2a内排序为:引进灌木>封育恢复>带状皆伐>孔状择伐>修枝抚育,抚育后2~4a排序为:引进灌木>带状皆伐>封育恢复>孔状择伐>修枝抚育>未封禁自然含水量在抚育后1~2a排序为:封育恢复>引进灌木>孔状择伐>带状皆伐>修枝抚育>未封禁,在抚育后2~4a表现出:引进灌木>封育恢复>孔状择伐>带状皆伐>修枝抚育>未封禁有效拦蓄量变化趋势表现为:带状皆伐>孔状择伐>引进灌木>封育恢复>修枝抚育>未封禁。 相似文献
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以纳帕海湿地原生沼泽作为参照 ,选择人为干扰下的沼泽化草甸 ,草甸和排干湿地开垦的耕地作为研究对象 ,研究人为干扰对纳帕海湿地土壤碳氮变化的影响。两年的定位研究结果表明 :沼泽土壤C/N值较高 ;人为干扰下纳帕海湿地土壤空间结构上土壤有机质 0～ 2 0cm表层与 2 0～ 4 0cm下层相差 4倍 ,水平分布上则随人为干扰加强、沼泽化过程减弱而降低 ,下降幅度高达 2 2 .92 %～ 6 9.6 4 %;土壤全氮及其空间分布呈现与有机质相同趋势 ,两者相关系数r=0 .98;NH 4 N、NO-3 N与全氮和水解氮相关系数分别为r=- 0 .74、r=- 0 .6 5 ,r=- 0 .81、r=- 0 .76。表明了纳帕海湿地沼泽土壤较低的矿化量和对碳的固定及较大的氮累积量 ,以及人为活动干扰后湿地土壤碳氮养分的释放变化。 相似文献
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通过室内控制培养试验方法,研究了不同温度和冻融循环过程对沼泽湿地土壤有机氮矿化影响。结果表明,湿地土壤中无机氮以铵态氮为主,温度和培养时间显著影响土壤有机氮的矿化,在温度-25~30℃之间,N的矿化速率、硝化速率随温度增加而增加,30℃时矿化速率（1.17mg.kg-1.d-1）和硝化速率（0.79mg.kg-.1d-1）最大。沼泽湿地土壤有机氮矿化培养时间以4~5周较为适宜。冻结温度和冻融次数显著影响土壤有机氮矿化过程,且-25~5℃冻融循环比-5~5℃冻融循环矿化累积量高。冻融循环促进了土壤有机氮的矿化,有利于土壤中有效氮的累积,为春季植物生长提供足够的氮素,对维持生态系统稳定有重要意义。 相似文献
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基于RS和GIS的绕阳河湿地时空演变及其驱动力分析 总被引：1，自引：0，他引：1
基于1975-2007年丰水期TM、ETM+、CBERS遥感数据资料,利用RS和GIS软件提取湿地类型转移矩阵,结合重心模型,分析了自1975年以来绕阳河沼泽湿地的时空演变过程及其驱动力.结果表明:1975-2007年绕阳河沼泽湿地面积占研究区总面积百分比由1.908%下降到0.068%,沼泽湿地主要转出类型为水稻田、裸地;1975-1988年绕阳河沼泽湿地重心向东北方向偏移了1.58 km,1988-2007年向西南方向偏移了3.21 km,32 a间整体向西南方向迁移2.36 km,距河流垂直距离缩短了1.79 km;水稻田的时空变化是沼泽湿地时空演变的直接驱动因子,人口是其最根本的驱动因子,地下水水位埋深、经济活动与沼泽湿地面积呈显著的负相关关系,河流面积与沼泽湿地面积则呈显著的正相关关系.概括来说,人类活动是绕阳河沼泽湿地时空演变的主要驱动力. 相似文献
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洞庭湖区湿地景观变化分析 总被引：3，自引：0，他引：3
洞庭湖湿地是我国最重要湿地系统之一,具有多方面功能和价值,主要由河流、湖泊、水田、沼泽、滩地、库塘等几种类型组成。本文利用1980年、1990年、2000年3个时段的Landsat MSS和TM影像及GIS技术对洞庭湖区湿地景观变化进行研究。结果表明,洞庭湖区湿地总面积呈减少趋势,人工湿地面积有所增加,自然湿地面积减少,其中湖泊面积减少最多。这是人类和自然共同作用的结果,其中人类对湿地的改造是导致变化的主要原因,但洞庭湖的泥沙淤积是湖泊面积减少的根本原因。湿地景观的改变导致该区生态环境质量下降,生态功能退化。 相似文献
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Methane emission from natural mires in the middle and southern taiga zones of Tomsk oblast was studied in the summer and fall of 2006. Methane fluxes (mg C/m2 per h) from different types of mires and different microelements of the surface topography were characterized by the following median values: 0.67 for a forested bog; 4.06 and 2.67 for hollows and elevations (hillocks) of an open (nonforested) mire, respectively; and 0.74 and 2.13 for hollows and ridges of a ridged bog, respectively. Based on these and the literature data on the areas of different types of mires in Tomsk oblast, annual methane emission from mire ecosystems of Tomsk oblast was estimated at about 0.50 × 1012 Tg C. This value comprised 0.3–1.0% of the global emission of methane from wetlands or 0.1% of the global methane emission from all sources. 相似文献
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C. C. Trettin W. M. Aust M. M. Davis A. S. Weakley J. Wisniewski 《Water, air, and soil pollution》1994,77(3-4):199-205
The wetland resources in the southern United States are diverse, being characterized by bottomland hardwoods, forested riparian zones, swamps, marshes, bogs, and fens. Recognizing the importance of the wetland resource, the need to develop information on the diversity of wetland types, and the evolving public debate regarding the protection and management of wetlands, this conference was organized to (1) provide a forum for the presentation and discussion of current research and information on wetland ecosystems, (2) to develop a basis on which to improve wetland conservation and management, (3) to provide a forum to encourage collaboration in the study and management of wetland resources, and (4) to suggest actions that would benefit wetland conservation and management. Twenty-three invited technical papers and three working group sessions addressed topics encompassing the full spectrum of wetland issues, including resource status, ecological and hydrological processes, management and conservation, and restoration and creation. Major findings discussed at the conference included the need to distinguish between functions and values, the development of a hydrogeomorphic classification system for assessing wetland functions, and assessment methodologies for planning and implementing effective wetland restoration projects. Papers summarizing the current understanding of wetland soil and vegetation processes in the region highlighted the important role wetlands play in landscape function, yet the understanding of those processes is incomplete. Insights developed from the study of wetlands in the interior southeastern United States have widespread applicability to other regions because of similarities in hydrogeomorphic setting and vegetation communities, and the management and conservation issues. 相似文献
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Interpreting the variations in atmospheric methane fluxes observed above a restored wetland 总被引：1，自引：0，他引：1
Mathias Herbst Thomas FriborgRasmus Ringgaard Henrik Soegaard 《Agricultural and Forest Meteorology》2011,151(7):841-853
The eddy flux of methane (CH4) was measured over 14 months above a restored wetland in western Denmark. The average annual daily CH4 flux was 30.2 mg m−2 d−1, but the daily emission rates varied considerably over time. Several factors were identified that explained some of this variation. (1) Grazing cattle moving through the source area of the eddy flux mast increased the measured emission rates by one order of magnitude during short time periods. (2) Friction velocity exerted a strong control on the CH4 flux whenever there were water pools on the surface. (3) An exponential response of the daily CH4 flux to soil temperature at 20 cm depth was found for most of the study period, but not for parts of the summer season that coincided with a low water level in the river flowing through the wetland. (4) Additional variations in the CH4 emission rates were related to the spatial heterogeneity of the source area. This area covered not only different plant communities but also a gravel road and a river surface, and it had a microtopography that visibly induced a large spatial variability in the wetness of the top soil. It is shown that the control mechanisms for the methane emission from restored wetlands are more complex than those reported for natural wetlands, since they include both management activities and slow adaptive processes related to changes in vegetation and hydrology. On the basis of eddy fluxes of carbon dioxide measured at the same site it is finally demonstrated that the variability in the CH4 fluxes strongly affects the greenhouse gas sink strength of the restored wetland. 相似文献
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Throughout the world, but particularly in tropical regions habitat loss and disturbance are considered detrimental to biodiversity. We examine the effects of disturbance by harvesting, burning and habitat fragmentation on six bird species associated with papyrus (Cyperus papyrus) swamps. The presence or absence of these species was verified in 93 wetlands in southern Uganda between June and August 2003. Disturbance was estimated directly by observation and indirectly from examining vegetation structure. Habitat fragmentation was quantified by delineating swamps on Landsat ETM images and applying ‘Fragstats’ to calculate relevant patch metrics. The occurrence of all six species was affected positively by increased swamp size, but birds were more likely to occur in small swamps at high altitude. The shape and proximity of swamps to neighbouring wetlands had little effect on occurrence. As altitude, habitat fragmentation and disturbance were correlated, determining avian responses to disturbance was problematic. However, the occurrence of all species was affected by disturbance, often showing unimodal responses, if disturbance was not considered in conjunction with habitat fragmentation. When the effects of habitat fragmentation and disturbance were analysed together, only the occurrences of papyrus yellow warbler and white-winged warbler were affected (positively) by disturbance. Results suggest that papyrus-dwelling passerines, except papyrus gonolek, are tolerant of low intensities of disturbance, a novel finding in the tropics. We recommend that policy-makers do not prohibit harvesting, thus generating good will and encouraging rural householders to comply with additional conservation policy. 相似文献
16.
Methane emissions from an acidic bog and a forested swamp in north Wales, U.K., were measured over a 12 month period. Along with the emission, hydrochemistry (DOC, SO4 2- and NO3 -) and physical factors (temperature, water table level) were determined. At the bog site, the methane emission ranged from 0.15 mg m-2 day-1 to 6.39 mg m-2 day-1, having two peaks in spring and late summer. In contrast, high emission was observed in October (38.95 mg m-2 day-1) and November (75.37 mg m-2 day-1)at the swamp site, which is concurrent with leaf litter production and high DOC concentrations. During the remaining months, the flux varied between –1.33 mg m-2 day-1 and 3.05 mg m-2 day-1. Correlation analyses showed that the methane emission from the acidic bog had a positive correlation with soil temperature, and negative correlations with sulfate and nitrate concentrations in the pore-water. However, a correlation with water table level was absent. Methane emission from the swamp exhibited a negative correlation with sulfate concentration. Our results confirm that methane emissions vary substantially between different types of wetlands, and suggest that under certain conditions, hydrochemistry may be a more critical controlling variable for methane emissions than temperature and water table level. 相似文献
17.
亚硝酸盐型甲烷厌氧氧化微生物生态学研究进展 总被引：3，自引：0，他引：3
亚硝酸盐型甲烷厌氧氧化(nitrite-dependent anaerobic methane oxidation,N-DAMO)是指以亚硝酸盐为电子受体将甲烷氧化为二氧化碳的微生物生理过程。虽然目前人们对于N-DAMO的研究主要集中于人工环境,但不断有证据表明N-DAMO菌广泛分布于不同类型生境(如河流、湖泊、湿地和海洋等)中,且在部分生境中已被证实N-DAMO反应的发生。这表明N-DAMO是一种被忽视的甲烷汇,其在全球温室气体减排中可能起着重要作用。本文介绍了N-DAMO菌的分类和生化反应机理,总结了N-DAMO菌在不同自然生态系统中的分布特征与作用强度,浅析了影响N-DAMO菌在自然生态系统中分布和发挥作用的主要环境因子,并探讨了N-DAMO反应作为一种被忽视的甲烷汇在控制温室气体排放中的贡献。 相似文献
18.
Natural wetlands are a significant source of atmospheric methane, an important greenhouse gas. Compared with numerous papers on measurements of methane emission from natural wetland surfaces, there are few reports on methane configuration and distribution within wetland soil profiles. By using a newly designed gas sampler, we succeeded in collecting free‐phase gas from beneath the water table down to 120 cm in a peat. The volumetric percentage of methane in the gas phase increased with depth and was generally more than 50% beneath the zone within which the water table fluctuates. The volume of the gas phase in the peat beneath the water table was estimated to be from 0 to 19% with significant variation with depth, suggesting uneven distribution of gas bubbles. Using the volume ratio of the gas and liquid phases and methane concentration data in the gas phase, as well as assuming that methane was in equilibrium (based on Henry's Law between the two phases), we calculated that ～60% of the methane accumulates in the form of bubbles. These results suggest the importance of ebullition in methane emission, which might be a major cause for the reportedly large variation of methane emission in both space and time. Most importantly, our results show the need to consider gaseous‐phase methane for understanding the production, transport and emission mechanisms of methane in wetlands, which has been overlooked to date. 相似文献
19.
Huai Chen Ning Wu Yanfen Wang Yongheng Gao Changhui Peng 《Water, air, and soil pollution》2011,217(1-4):173-183
Methane fluxes in alpine ecosystems remain insufficiently studied, especially in terms of the magnitude, temporal, and spatial patterns. To quantify the mean methane emission of alpine ecosystems, methane fluxes were measured among six ecosystems and microsites within each ecosystem at Zoige National Wetland Reserve. The average methane emission from Zoige Plateau was 2.25 mg CH4 m?2?h?1, which fell into the range of methane emission rate reported by a number of studies in other alpine wetlands. Prevailing ecosystem types had important impacts on the methane flux on the landscape scale. In the wet ecosystems, the microsites had different methane emissions resulting from the differences in the depth of water table and associated vegetation characteristics. The identification of the microsites based on their vegetation characteristics thus allows upscaling of methane emissions in these ecosystems. However, in the dry ecosystems showing even methane uptake, the spatial variation in the methane fluxes was low and the vegetation has a poor predicative value for the methane fluxes. There, the soil porosity linked to the gas diffusion rate in soil would be the key factor explaining methane fluxes. 相似文献
20.
Shen Yu 《Soil biology & biochemistry》2009,41(12):2394-2405
Wetlands are subject to changes in soil moisture as a result of both short-term seasonal climate variations and long-term changes in regional water resource management, both of which can modify the dynamics of ground and surface water inputs. In the New Jersey Pinelands, forested wetlands that differ in both plant communities and soil structure occur along a topographic and hydrological gradient associated with an unconfined aquifer. Proposed groundwater withdrawals may affect water content of soils along this gradient. We hypothesized that prolonged changes in soil moisture would alter net nitrogen mineralization and nitrification rates in proportion to the amount of moisture change, and that these changes would be similar for the different soils along the drainage catena. Soils from two catenary sequences of wetlands, including pine-dominated (driest landscape position), hardwood-dominated, and Atlantic white-cedar-dominated (wettest landscape position) communities were used in long-term laboratory incubations (36 weeks). Production of NH4+-N, NO3−-N, and dissolved organic N were measured under two sets of conditions: constant moisture levels of 100%, 60% and 30% water-holding capacity (WHC), and fluctuating moisture levels (alternating 2 week periods at 100% and 30% WHC). In soils from most of the wetlands, we observed increases in net mineralization and nitrification when constant low-moisture conditions were established, but not under fluctuating conditions. Contrary to expectations, responses to the drying treatments varied between wetland types and between replicate wetlands of each type. Under constant-moisture conditions, nitrification increased more in cedar swamps than in either type of pine wetland. Under all conditions, soils from all the wetlands within one of the catenas produced more inorganic and organic soluble N than did the wetlands from the other catena, suggesting that area-wide effects are as important as wetland type in regulating production of soluble N. Within both catenas, pine-hardwood wetlands generated more soluble N under all moisture conditions than did either pine-dominated or cedar wetlands. Our results suggest that changes in soil moisture due to management of water resources will affect N cycling in wetland soils, but that the magnitude of the effects, and the potential for large releases of nitrate, will depend on the specific soil properties of affected wetlands. 相似文献