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1.
采伐强度对小兴安岭低质林分土壤碳通量的影响 总被引：6，自引：0，他引：6
针对择伐后的小兴安岭低质林分,采用LI-8100碳通量自动监测系统在春、夏、秋、冬4个季节对低质林分土壤碳通量进行观测,运用统计分析方法,分析采伐强度对土壤碳通量、土壤温度与湿度的影响。结果表明:采伐区的土壤碳通量高于对照区,随采伐强度的增加土壤碳通量呈现波动性,从采伐强度22%～47%,碳通量逐渐减小,之后趋于平稳,春、夏、秋、冬4个季节土壤碳通量的最大值出现在低度和中度采伐强度林分条件下;随采伐强度增加土壤温度增加,土壤湿度减少,土壤碳通量与距地表10cm处的土壤温度的关系符合指数模型,土壤碳通量与土壤湿度的关系符合一元二次模型;从标准化回归方程看出,土壤碳通量主要由土壤温度与湿度共同影响,且土壤湿度对碳通量的影响大于土壤温度的影响。采伐强度与土壤碳通量具有负相关性,二者的关系为双曲线。 相似文献
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采伐强度对森林天然更新的影响 总被引：6，自引：0，他引：6
采伐作业时，所选择的采伐强度，对森林天然更新影响非常大的，因地、因林、科学地选择采伐强度和伐后的郁闭度，以便使林林更快，更好地恢复和增长，通过大量调查资料发现采伐强度在２３％－３０％，伐后郁闭度在０．４８－０．６２之间更新的速度最佳。 相似文献
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利用LI-COR-8100土壤CO2通量自动测量系统测定了湖北赤壁幕布山区采伐毛竹林土壤表面CO2通量及5 cm深度的土壤温度、湿度,研究了采伐对毛竹林土壤呼吸的影响,并用壕沟法区分各组分呼吸。结果表明:采伐显著增加了毛竹林的土壤温度,但对土壤湿度无显著影响;采伐能增加土壤呼吸、凋落物呼吸与矿质呼吸,但降低了根系呼吸;土壤总呼吸及组分呼吸与土壤温度呈指数相关(R2=32.63%84.50%),与土壤湿度呈线性相关(R2=40.60%93.50%),运用土壤温度、湿度复合模型能提高预测土壤呼吸的准确性(R2=41.40%96.20%)。采伐毛竹林土壤呼吸的增加主要因为采伐后土壤温度升高所致。 相似文献
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不同强度采伐5年后杉阔混交人工林土壤呼吸速率差异 总被引：1，自引：0，他引：1
【目的】比较不同采伐强度下闽北杉阔混交人工林土壤及其各组分的呼吸速率差异,揭示土壤总呼吸速率季节变化的主要影响因子,以期为区域森林采伐对土壤呼吸速率的影响研究提供科学依据。【方法】以闽北杉阔混交人工林为研究对象,2011年8月实施了不同蓄积量采伐强度(中度择伐34.6%、强度择伐48.6%、极强度择伐67.6%、皆伐)作业试验,并与未采伐对照;2016年7月—2017年7月运用Li-8100 A土壤碳通量自动测量系统,对土壤及其各组分的呼吸速率、土壤5 cm深处的温度和湿度开展了为期1年的定位观测。【结果】未采伐和各种强度择伐5年后,土壤总呼吸速率最大值都出现在7月份,最小值出现在1—3月份;皆伐5年后,土壤总呼吸速率最大值出现在6月份,最小值出现在11月份;各种强度采伐林地的矿质土壤呼吸速率与未采伐林地无显著差异( P >0.05);各种强度择伐林地的凋落物和根系呼吸速率都与未采伐林地无显著差异( P >0.05),而皆伐林地的凋落物和根系呼吸速率都显著低于未采伐林地( P <0.05),分别比未采伐林地(1.45和1.11 μmol ·m^-2 s^-1 )减少了0.93和0.53 μmol ·m^-2 s^-1;各种强度择伐林地的土壤总呼吸速率与未采伐林地无显著差异( P >0.05),而皆伐林地的土壤总呼吸速率显著低于未采伐林地( P <0.05),比未采伐林地(4.39 μmol ·m^-2 s^-1 )减少了1.64 μmol ·m^-2 s^-1;中度、强度和极强度择伐林地5 cm深处的土壤温度与未采伐林地没有显著差异( P >0.05),而皆伐使林地土壤温度显著升高( P <0.05),比未采伐林地(18.52 ℃)增加了4.7 ℃;中度、强度择伐林地的5 cm深处土壤湿度与未采伐没有显著差异( P >0.05),而极强度择伐和皆伐使林地土壤湿度显著降低( P <0.05),分别比未采伐林地(30.67%)减少了2.17%和3.98%;土壤总呼吸速率的土壤温度指数模型拟合效果最优,能解释未采伐和各种强度择伐林地土壤总呼吸变化的77.8%~83.3%以及皆伐林地土壤呼吸变化的35.5%;未采伐、中度、强度和极强度择伐林地土壤总呼吸的温度敏感性参数Q 10 为1.77~2.72,皆伐林地的 Q 10 为1.49。【结论】不同强度采伐5年后,各种强度择伐林地土壤及其各组分的呼吸速率与未采伐林地没有显著差异;皆伐使凋落物呼吸速率、根系呼吸速率和土壤总呼吸速率都显著降低;各种强度择伐没有改变土壤总呼吸速率的季节变化规律,但皆伐使土壤总呼吸速率最大和最小出现时间有所提前;研究区土壤温度是土壤总呼吸速率季节变化的主要影响因子。 相似文献
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择伐对小兴安岭地区针阔混交林土壤呼吸温度敏感性的影响 总被引：1，自引：0，他引：1
利用LI8100土壤二氧化碳排放通量全自动测量系统,测定小兴安岭地区针阔混交林不同强度择伐后4年的林地土壤呼吸速率和土壤温度。运用Q10模型分析择伐后林地土壤呼吸速率对土壤温度的敏感性。结果表明:择伐后林地Q10值高于未采伐林地,较高强度(60%,71%)的择伐使土壤呼吸速率对土壤温度具有高的敏感性。这一现象是3个土壤各组分呼吸对土壤温度响应综合作用的结果。枯枝落叶层呼吸速率对土壤温度的敏感性较差,根呼吸速率和矿质土壤层呼吸速率对土壤温度的敏感性较高。 相似文献
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采伐强度对林分蓄积生长量与更新影响的研究 总被引：18，自引：0，他引：18
通过对大兴安岭、小兴安岭和长白山部分林区不同林型的调查，分析了不同采伐强度对林分蓄积生长量和更新效果的影响，并应用统计学原理，对不同采伐强度与林分年平均蓄积生长量和年平均更新株数进行拟合分析，得出不同林型不同采伐强度与林分蓄积年平均生长量和年平均更新株数的相关关系。结果表明：采伐强度与林分年平均蓄积生长量和更新株数间呈抛物线关系。 相似文献
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介绍了抚育采伐作业在实际操作中的程序与做法,分析了采伐强度控制、采伐木选择和结束期确定等方面存在的影响抚育采伐成效和降低森林培育效率等有关问题,提出了采伐强度要因地因林制宜、适度放宽,采伐木选择要边选边伐、技术人员跟班作业,结束期要根据经营目标由经营主体自主确定等几项改进措施,以期为不断提高抚育采伐成效提供参考。 相似文献
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不同经营方式对人工林土壤化学性质的影响 总被引：1，自引：0，他引：1
在人工林内分别设置六块采伐样地,采伐强度依次为10％、15％、20％、25％、30％和35％,每块样地设置6、10、14和18m四种带宽,在每条采伐带内取土壤样本,对其化学性质进行测定,分析不同采伐强度、不同带宽对土壤化学性质的影响,从而选择用材林的最佳经营方式. 相似文献
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【目的】以崇礼冬奥核心区华北落叶松人工近熟林为研究对象，探讨目标树抚育间伐采伐木选择方法及其对林分空间结构的影响，为更加合理开展森林经营活动、促进人工林质量提升提供科学依据。【方法】设置并调查6块面积0.09 hm2(30 m×30 m)标准地，按125株·hm-2目标树密度，采用定性与定量指标相结合的方法标记目标树。基于树冠重叠和树冠光竞争高度构建采伐木选择指标，设置不同光竞争截止系数(c)模拟选择采伐木，分析采伐强度变化，运用角尺度、混交度、密集度、交角竞争指数、林层指数和综合空间结构指数分析不同c值下目标树和林分空间结构指标的变化。【结果】c取值在0～1之间时，株数采伐强度和断面积采伐强度在10%～35%范围内变化，且呈随c值增大而降低的相同变化趋势。经模拟采伐后目标树空间结构得到优化，改善幅度随采伐强度增大而增大。综合空间结构指数在c值0.6时达到最大提升幅度45.50%，角尺度和密集度在c值0.7时变化幅度最大，分别为17.93%和46.83%，其他空间结构参数在c值0.6时达到最大变化幅度。抚育间伐可同时优化林分空间结构，对林分树... 相似文献
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《Scandinavian Journal of Forest Research》2012,27(1-4):7-16
The study describes effects of clear‐felling and soil scarification on the N concentration and pH of soil water in experimental plots previously supplied with different doses of N. The experiment is situated in central Sweden in a former Pinus sylvestris L. stand. Over a 20‐yr period, plots were fertilized three times with ammonium nitrate, resulting in total doses of 360, 720, 1080, 1440 and 1800 kg N ha‐1. Soil water was sampled at a depth of 40–50 cm using suction lysimeters, and analysed for N and pH. The study covers one growing season before clear‐felling and six and four growing seasons after clear‐felling and soil scarification, respectively. Statistically significant (p < 0.05) elevations in total N and nitrate‐N concentrations were noted in the fourth to the sixth growing seasons after clear‐felling in the plots that had received 1800 kg N ha‐1, and in the fifth and sixth seasons in the plots that had received 1440 kg N ha‐1. Ammonium‐N concentrations were not significantly affected. After clear‐felling, total N and nitrate‐N increased with time at a higher rate in the plots that had received 1440 and 1800 kg N ha‐1 doses compared with the control. In the sixth post‐cutting season, the nitrate‐N concentration was 0.26 mg l‐1 in the control and between 0.51 and 4.0 mg l‐1 in the various fertilized plots. Before clear‐felling, a linear relationship between pH and fertilizer dose was absent. After clear‐felling, negative relationships prevailed, but they differed significantly from the pre‐cutting relationship only during the fourth, fifth and sixth post‐cutting seasons. In the sixth post‐cutting season, the pH was 6.0 in the control, and 6.1, 5.7, 5.6, 5.2 and 4.3 in the plots supplied with 360, 720, 1080, 1440 and 1800 kg N ha‐1 doses, respectively. The absolute difference in pH between the sixth growing season after clear‐felling and period before clear‐felling increased linearly with increasing fertilizer dose (p < 0.05, R 2 = 0.79). Before clear‐felling, nitrate‐N was elevated only in the plots that had received 1800 kg N ha‐1. After clear‐felling, nitrate‐N seemed to increase in all fertilized plots, but the increase began first in the plots receiving the highest fertilizer dose. It was not until the fifth and sixth growing seasons after clear‐felling that nitrate‐N concentrations appeared elevated in all fertilized plots compared with the control. It seems likely that nitrification caused the increases in nitrate‐N because nitrate‐N accounted for most of the variation in pH in the fourth to the sixth growing seasons. Disc trenching was simulated around some of the lysimeters so that 50% of the soil was disturbed. This did not significantly affect the N concentration or pH of the soil water during the first 4 yrs after scarification. 相似文献
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测定了海南岛霸王岭热带山地雨林不同择伐强度经营试验初期土壤 C、N含量及其储量 ,结果表明 :原始热带山地雨林土壤 C、N背景值分别为 10 8.91t· hm-2 、9.58t· hm-2 ,表层 50 cm土壤 C储量占深 10 0 cm土层 C储量的 77.6 % ,相应的 N储量占 73.8% ;30 %、50 %择伐强度经营 5个月后林地土壤 C储量分别比原始林降低 4 .5%和 5.3% ,但 30 %强度经营林地土壤 C/N接近未采伐的原始林。结果可作为对热带山地雨林选取持续经营模式的动态参考指标 相似文献
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《Scandinavian Journal of Forest Research》2012,27(2):179-191
The effects of felling season, log storage and kiln drying on stemwood discoloration of sixty mature silver birches ( Betula pendula ) were studied and provided with CIEL*a*b* colour coordinates. The colour differences were expressed as j E* including split up of j L*, j a* and j b*. The results showed that fresh wood colour depends on the felling season: light and pale colours were recorded for samples taken from autumn- and winter-felled trees, whereas the colour of fresh wood was considerably darker if the felling took place in the spring or summer. After storage, notable changes in colour were observed. After drying, all samples showed low lightness, moderate redness and relatively high yellowness under the drying conditions used in the study regardless of the felling season or duration of storage. The main colour component responsible for the discoloration was lightness, while chroma values redness and yellowness played a minor role. 相似文献
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在森林生态系统中 ,火是一种相当普遍的自然现象 ,森林火灾和森林水文二者有着密切的关系。森林火灾对水的影响是间接的 ,主要表现为火烧后植被、地被物、土壤以及生态环境的改变影响水分循环过程、水质、水生生物等方面。火对水文的影响有大有小 ,它取决于火强度和频度。轻度野火或计划火烧对水文可能不产生明显影响 ,但是 ,频繁的或严重的野火却可以导致乱砍滥伐所造成的类似水文变化 相似文献
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小兴安岭天然针阔混交林择伐后土壤呼吸动态变化 总被引：6，自引：2，他引：4
采用LI-8100土壤CO2排放通量全自动测量系统,针对小兴安岭带岭林业局东方红林场不同择伐强度的针阔混交林样地,测定林地生长季土壤呼吸速率以及10cm土深处的温度和湿度,探讨生长季土壤呼吸的日变化、季节变化和年通量。结果表明：土壤呼吸日变化动态与土壤温度日变化动态基本一致,呈明显的单峰曲线。采伐强度不同间接影响着土壤呼吸速率。研究表明：针阔混交林土壤呼吸速率均值在0．6—8．2μml·m^-2·s^-1之间,高于同纬度其他地区;雨季（6月、7月、8月、9月）土壤呼吸明显大于旱季（5月、10月、11月）;针阔混交林生态系统土壤呼吸不同月份通量值在1．68～18．82mol·m^-2之间,最大值和最小值分别出现在7月和11月。与北半球温带森林生态系统土壤呼吸变化趋势基本一致。2006年针阔混交林生态系统土壤呼吸通量为84．37mol·m^-2,与朝鲜半岛硬阔混交林土壤呼吸相似,但比一些热带地区的结果偏大。 相似文献
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《Forest Ecology and Management》1998,108(3):251-260
In East Kalimantan (Indonesia), impacts of conventional (CNV) and reduced-impact logging (RIL) on forest ecosystems were compared on the basis of pre- and post-harvesting stand inventories. There was a positive and significant correlation between the proportion of trees damaged by felling and the density of trees felled. Logging intensity ranged from 1 to 17 trees ha−1(9–247 m3 ha−1) and averaged 9 trees ha−1 (86.9 m3 ha−1). The study has shown that with RIL techniques, logging damage on the original stand can be significantly reduced by 50% compared with conventional logging. However, this 50% reduction in logging damage, was dependent on the felling intensity. With a felling intensity of 8 stems ha−1 or less, RIL techniques only damaged 25% of the original tree population whereas 48% were damaged with conventional techniques. Above this felling intensity (i.e. 8 stems ha−1), the effectiveness of RIL in limiting forest damage was significantly reduced, mainly because of the increasing felling damage. Moreover, the removal of all harvestable timber trees, leaving only few potential crop trees, will result in a seriously depleted residual stand. Because of the high damage involved by high felling intensity, leaving few potential crop trees, and the yield capacity of the remaining stand, acceptable harvesting volume will not be reached within the felling rotation of 35 years. It is concluded that silvicultural system based on diameter limit alone, as is the Indonesian system (TPTI), cannot be compatible with sustainability and more sophisticated harvested-selection rules are needed. 相似文献
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通过刺五加林上层木不同强度的间伐,营造红松刺五加混交林和抚育时保留刺五加的3种技术措施,增加刺五加的贮量,保证了红松的正常生长。在不同强度间伐试验中,刺五加贮量分别增加了56%和13%;在红松造林地进行保留刺五加的抚育试验中,每亩刺五加贮量分别达到42102g和15301g。 相似文献
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次生阔叶林改建为食用菌原料林后的群落恢复和林分生长 总被引：6，自引：0，他引：6
选择12年生林相较好的天然次生阔叶林,通过择伐更新和皆伐人促更新2种经营方式定向培育食用菌原料林。研究发现,择伐经营的经济效益较高,且有利于群落的快速恢复,经过7a的封育,林分蓄积量已达到择伐前的水平。皆伐人促更新获得的食用菌材虽较择伐利用高出40%左右,但因经营强度过大,保留的幼树受损严重而不利于伐后林木的生长与恢复,封育期内蓄积增长量分别为择伐更新和对照未经营区的64 7%和73 41%。动态监测结果显示,采用择伐和皆伐人促更新措施后群落恢复较快。疏伐后因透光度的急剧增加,阳性和中性树种大量侵入,地面芽植物和1年生植物的比例增高。到第7a时,高位芽植物的比例已接近未经营区的状态,乔、灌、草各层的物种多样性指数高于未经营的天然阔叶林,物种均匀度则与其相近。研究还发现,2种更新经营方式对土壤养分的损失较小,经过7a的恢复,林地土壤肥力已基本达到原有天然林水平。 相似文献