不同密度毛竹林枯落物层水文特性研究

对黄山区4种密度毛竹纯林枯落物层的储量、最大持水量、最大持水率、吸水速率、有效拦蓄量等水文特性参数进行了研究。结果表明:(1)不同密度毛竹林枯落物储量、厚度及自然含水率均存在较大差异;不同林分枯落物储量为3.98 6.00 t·hm-2,其中,以3 000株·hm-2的林分枯落物储量最高。(2)4种密度毛竹林下枯落物最大持水率为317.09%347.58%,密度为3 000株·hm-2时,毛竹林枯落物层最大持水量达到20.70 t·hm-2。(3)4种密度毛竹林枯落物层持水量(S)与浸泡时间(t)的关系为S=alnt+b(a为方程系数,b为方程常数项),其吸水速率(V)与浸泡时间(t)的关系为V=ctd(c为方程系数,d为方程指数);在0 4 h内枯落物吸水速率急剧下降,4 h后明显减缓。(4)密度对毛竹林枯落物水文特性有一定影响,选择适宜的营林密度对于提高毛竹林枯落物层水文生态功能具有重要的作用。     

闽北毛竹林枯落物层持水功能研究

以杉木林和常绿阔叶林为对照,对闽北典型毛竹林(杉竹混交林、毛竹纯林、竹阔混交林)林下枯落物储量、持水特性及其对降雨的拦蓄能力进行研究,结果表明:(1)各林分未分解层、半分解层和已分解层枯落物储量、最大持水量和有效拦蓄差异较大,但均以半分解层最高,分解层次之,未分解层最小;杉木纯林枯落物总储量、最大持水量和有效拦蓄均最高,分别为14.6 t·hm^-2、2.668 mm和1.43mm,竹阔混交林次之,分别为7.0 t·hm^-2、1.298 mm和0.76 mm,毛竹纯林最低,分别仅为4.7 t·hm^-2、0.916 mm和0.58 mm。(2)5种林分各层枯落物持水量与浸泡时间的关系为:S=k ln(t)+p,在0 - 2 h内,枯落物持水量迅速增加,此后增加速度逐渐减缓;其吸水速率与浸泡时间的关系为:V=at^-1+b,在0 - 1 h内,枯落物吸水速率迅速下降,2 h后下降速度逐渐减缓。(3)竹阔混交林枯落物持水能力虽小于杉木纯林但在竹林中最强,对此,在竹林改造和竹林经营过程中应加以重视。     

密度对毛竹林水源涵养能力的影响

以崇阳县毛竹为研究对象,在4种密度(D1)1 300±100、(D2)1 900±100、(D3)2 500±100及(D4)3 100±100株·hm~(-2)毛竹林分内通过标准地设置与调查对毛竹林分水源涵养能力进行了研究。结果表明,虽然不同毛竹林密度林冠层截留率之间的差异不显著,但截留量之间的差异极显著。半分解以及未分解凋落物持水量与浸泡时间之间均为对数方程,半分解以及未分解凋落物吸水速率与浸泡时间之间均为幂函数方程。不同密度凋落物最大持水量0.81~1.21 mm,并随林分密度增加而增加。凋落物总最大持水率380.39%~402.13%。林分有效拦蓄量0.75~0.92 mm,有效拦蓄率292.92%~311.31%,并密度增大而增大。毛竹林土壤土壤含水率11.21%~13.70%,土壤容重1.19~1.34 g/cm~3,毛管总孔隙度52.89%~54.77%,土壤毛管总孔隙度随土层深度的增加而减小,土壤非毛管孔隙度9.39%~10.22%。林分密度对土壤物理性状及其土壤渗透性能影响均不显著。毛竹林土壤饱和蓄水量3 173.35~3286.11 t·hm~(-2),不同密度毛竹林分土壤层饱和蓄水量之间的差异不显著。虽然不同密度毛竹林分土壤毛管蓄水量之间的差异不显著,但非毛管蓄水量差异显著。毛竹林水源涵养总量584.15~626.58 t·hm~(-2),土壤蓄水量、林冠截留量及凋落物持水量分别占96.41%~97.91%、0.79%~1.51%及1.30%~2.07%。     

阿什河上游小流域主要林分枯落物层的持水特性

在阿什河上游的帽儿山实验林场境内,选取代表性的6种林分类型,测定了各林分枯落物层的蓄积量,采用室内浸泡法对持水能力进行研究。结果表明:6种林分枯落物层厚度为2.8 5.5 cm;枯落物总蓄积量为9.27 39.81 t·hm^-2;最大持水量为25.65 136.83 t·hm^-2;最大拦蓄水量为21.02 87.53 t·hm^-2;总有效拦蓄水深为1.72 6.71 mm。6种林分枯落物层的持水能力排序为:兴安落叶松林>针阔混交林>红松林>蒙古栎林>樟子松林>水曲柳林。对6种林分枯落物的持水量、吸水率随浸泡时间的变化进行了回归拟合,表明枯落物持水量与浸泡时间存在对数关系,枯落物吸水速率与浸泡时间存在幂函数关系。     

Effect of wide spacing on increment and branch properties of young Norway spruce

The effects of stand density on increment and branch properties were studied in three spacing experiments of Norway spruce [Picea abies (L.) Karst.]. The stand densities ranged from 350 stems ha⁻¹, regarded as open-grown trees, up to 1,600 stems ha⁻¹, corresponding to the density recommended for forestry practice. Properties of all the branches were measured from the stem apex downwards. The study material included a total of 5,661 branches from 45 trees. Increasing stand density resulted in a decrease in radial increment as well as shorter and narrower crowns, but it had no effect on height increment. The average number of spike knots per tree was 0.87, 0.27, and 0.33 in densities of 350, 700 and 1,600 ha⁻¹, respectively. Additionally, in the widely spaced stands of 350 stems ha⁻¹, the fraction of trees having spike knots was high (over 50%). At a density of 1,600 ha⁻¹, the sample trees had somewhat less branches in a whorl compared with the more widely spaced plots. The most pronounced effect of stand density was the increase in branch diameter with decreasing stand density. At a density of 350 ha⁻¹, the maximum branch diameter of all the sample trees exceeded the diameter limit of quality class B in the European quality requirements for round wood. The results give some indication that trees subjected to severe competition would produce smaller branches per unit of crown projection area. However, the possibilities for reducing branch dimensions relative to stem and crown size through competition appear quite restricted.     

宁夏六盘山不同林龄华北落叶松人工林枯落物水文效应

目的 探究林龄对华北落叶松林枯落物水文效应的影响。 方法 于2017年6月在宁夏六盘山香水河小流域选择4种林龄阶段（16、25、34、43a）的华北落叶松人工林样地,调查林分结构和测量林下枯落物蓄积量、厚度、持水量等指标,分析不同林龄华北落叶松枯落物层持水能力差异。 结果 研究表明：（1）华北落叶松枯落物厚度介于4.5~6.0 cm,总蓄积量在29.08~33.21 t·hm-2,且半分解层蓄积量高于未分解层蓄积量,4种林龄枯落物厚度与蓄积量均表现为成熟林>近熟林>中龄林>幼龄林。（2）各龄林枯落物最大持水量介于79.47~110.05 t·hm-2,成熟林最大;最大持水率变动在273.32%~341.27%,中龄林最大。（3）各龄林枯落物持水量、吸水速率与浸水时间动态变化均类似,枯落物持水过程表现为浸水0.5 h内吸水速率最大,4 h之后吸水速率趋于平缓,10 h后枯落物持水量基本饱和,持水量与浸水时间均呈明显对数关系（R2>0.92）。（4）各龄林枯落物有效拦蓄量在43.64~70.52 t·hm-2之间,成熟林拦蓄能力最强。 结论 综合分析4种林龄枯落物水文效应,成熟林枯落物层水文功能最强。     

Light modification in a developing silvopastoral system in the UK: a quantitative analysis

Transmitted photosynthetically active radiation (PAR) was measured in eight-year-old silvopastoral stands at three different locations in the UK by using PAR sensors randomly distributed between four adjacent trees planted in a square pattern. Two densities (100 stems.ha^-1 and 400 stems.ha^-1 were compared. The annual carrying capacity (live weight of the animals that a plot supports) was also recorded as an indirect figure of the overall agricultural production of the system. The silvopastoral plots received less radiation than the agricultural plot without trees, the 400 stems.ha^-1 treatment being more shaded than the 100 stems.ha^-1. Over the measurement period, on some special days, a maximum of 30% of the incoming radiation was intercepted on the 400 stem.ha^-1 treatment with the largest trees. The amount of light intercepted was highly correlated with the type of weather and the leaf area development of the trees: the brighter the day and more expanded the leaf area, the higher was the proportion of radiation intercepted by the tree. However, over the measuring period, a small amount of radiation was intercepted by the tree canopies. As a consequence, no differences were observed in the annual carrying capacity. This revised version was published online in June 2006 with corrections to the Cover Date.     

小兴安岭南坡4种林分类型枯落物水文特性研究

对小兴安岭南坡的红松林、落叶松人工林、杨树林和白桦林的枯落物储量、持水量、吸水速率等水文特征参数进行调查分析研究及其持水特性试验,结果表明,红松林下枯落物储量最大53.89 t/hm^2,其后依次为杨树林42.66 t/hm^2、落叶松人工林30.54 t/hm^2、白桦林最小20.03 t/hm^2。在这4种林分枯落物中,红松林的有效拦蓄量为最大,相当于14.56 mm的降雨。经数据分析拟合,得到林下枯落物未分解层和半分解层吸水速率与浸水时间之间存在显著的负指数相关性（R〉0.99）。     

杉木等几种人工林凋落物持水特性研究

对粤西、粤北杉木、马尾松、湿地松、马占相思、尾叶桉、黎蒴和毛竹等7种主要人工林凋落物的持水量、持水率和吸水速率进行测定。结果表明,马占相思、尾叶桉、黎蒴、湿地松、毛竹、马尾松和杉木的凋落物最大持水率分别为284.74%、253.36%、236.47%、226.06%、212.06%、187.68%和181.16%,树种间差异较大。凋落物持水量和持水率均随浸泡时间增加呈对数方程W=a＋blnt增加。7种林分凋落物的吸水速率在浸泡0.5-1.5 h时均为马占相思〉尾叶桉〉湿地松〉毛竹〉黎蒴〉马尾松〉杉木,各林分凋落物吸水速率WA随浸泡时间t的延长呈方程WA=a.t^-b下降。马占相思凋落物水源涵养能力最强,杉木最弱,阔叶树大于针叶树。     

丹江口湖北库区马尾松人工林水文生态效应

采用野外实地观测与室内浸水法,对丹江口湖北库区龙口林场5种类型马尾松林分枯落物蓄水、土壤理化性质和蓄水能力、地表径流和土壤侵蚀等水文效应进行了研究。结果表明：①不同类型马尾松林枯落物层最大持水量间存在显著差异,变化范围在45．83-93．32t·hm^-2,为松柏混交林〉针阔混交林〉低密度马尾松林〉中密度马尾松林〉高密度马尾松林。有效拦蓄量变化范围在29．83-41．79t·hm^-2,为中密度马尾松林〉松柏混交林〉针阔混交林〉低密度马尾松林〉高密度马尾松林。②随着土壤深度的增加,土壤容重呈增加的趋势,而总孔隙度呈逐渐递减的趋势。不同类型马尾松土壤贮水能力差异明显,表现为针阔混交林〉低密度马尾松林〉中密度马尾松林〉松柏混交林〉高密度马尾松林,针阔混交林约是高密度马尾松林的1．25倍。③不同森林类型地表径流量在14．68-29．56m^3·hm^-2之间,土壤侵蚀量在2．01～4．15m3·hm^-2之间,且均以栎类次生林最优,松柏混交林次之,马尾松纯林最低。总体而言,综合利用抚育择伐和人工诱导自然更新的方法,人工诱导马尾松纯林逐步向针阔混交林发育,可更有效提高水土保持功能。     

资兴市不同森林恢复与发展模式水源涵养功能初探

采用野外调查与长期定位监测相结合的方法,整体系统地研究了资兴市为恢复雪灾受损森林资源构建的不同森林经营模式水源涵养功能,旨在定量分析不同森林恢复与发展模式水源涵养功能大小,为其可持续发展提供数据支撑。研究结果表明:监测期间,各林分不同雨强条件下林冠层截留量各不相同,差异明显,最大的是M8,达54.8 mm,最小的是M6,仅48.59 mm;各林分灌草层持水量存在差异,M6(3.168 mm)最大;枯落物层持水量差异明显,M8(31.838 mm)最大,M6(23.13 mm)最小;林地土壤贮水能力M8与M6、M7之间差异显著,M6与M7之间差异不大。各林分水源涵养总能力大小为M8(1 123.624 mm)CK8(1 068.543 mm)M7(1 047.623 mm)CK7(1 039.983 mm)M6(1 001.815 mm)CK6(965.779mm),以M8水源涵养能力最大,达到1 123.624 mm,约占年降雨量的84%,各模式林分引用了适生树种,具有完整的林冠层、灌草层和枯落物层,形成了多功能复层混交林,改变了林分对降雨的再分配,水源涵养总能力较强。各模式水源涵养能力略强于对照,但由于项目执行时间不长差异较小。     

准格尔旗黄土丘陵区人工林水文生态效益评价研究

就黄土丘陵区主要植被类型人工油松成熟林、人工油松中龄林、人工油松幼龄林、人工沙棘林、人工柠条林、天然草坡的枯落物容水特征和林地土壤水分物理性质进行了测定,并以坡耕地作对照。结果表明：人工油松成熟林的枯落物吸水量为22．6t／hm2,是中龄林和幼龄林的5～9倍,是灌木林的2．4～3倍,是天然草地的10倍多。0～40cm土层土壤最大持水能力油松成林、油松幼林、浦松中龄林、人工沙棘林、人工柠条林、天然草地、农耕地依次为2260．05、1935．6、1935．6、1820．1、1597．65、1666．05、1600．2t／hm2;油松成林、油松幼林、油松中龄林、人工沙棘林、天然草地0—40cm土层土壤最大持水能力分别比对照农耕地提高659．85、335．4、335．4、219．9、65．85t／hm2。在土壤总孔隙度、毛管孔隙度、毛管最大持水量、土壤最大持水能力等水土保持及水源涵养功能指标诸方面,人工油松林均优于灌木林和天然草地。     

北亚热带6种森林类型凋落物分解过程中有机碳动态变化

运用凋落物野外分解模拟实验的方法,对北亚热带地区6种主要森林类型凋落物分解过程中有机碳的变化进行了研究,结果表明:(1)6种土地利用类型森林凋落物分解过程中,有机碳相对含量在分解初始阶段都呈现增加的趋势,表现为凋落物有机碳相对含量的积累过程;分解开始的第3～4个月后,凋落物有机碳相对含量下降;经过1 a的分解周期以后,粗放经营毛竹林凋落物有机碳相对含量变化最大,下降11.7%;(2)集约经营毛竹林凋落物有机碳数量从分解开始就减少,而其它几种类型分解初期有机碳数量都表现一个净积累的过程,然后才逐步释放;经过1 a分解周期以后,粗放经营毛竹林凋落物53.8%的有机碳净释放;凋落物有机碳释放速率由高到低的顺序为:粗放经营毛竹林、早竹林、杉木林、天然次生林、集约经营毛竹林、马尾松林;(3)6种土地利用类型森林凋落物在分解过程中,有机碳剩余率随时间变化的模型都极其显著地符合分解指数模型,因此都可以用指数方程表达;(4)影响凋落物分解的环境因子所发挥的作用不尽相同,凋落物的分解速率和温度之间呈现显著的正相关关系.     

Timing and intensity of precommercial thinning in Pinus sylvestris stands

The effects of timing and intensity of precommercial thinning were studied in three Scots pine artificially regenerated stands on Vaccinium forest sites in southern Finland. A two-level factorial design (3×3) was used in each stand: thinning at dominant height of 3, 6 and 9 m to 1000, 1600 and 2200 stems ha^?1. The effects of the treatments were analysed after a period of 23–25 yrs when the dominant height was 14–15 m. Early thinning resulted in the highest standing volume and amount of merchantable wood, and also in slightly accelerated height development. Thinning to 1000 stems ha^?1 caused a considerable production loss, but there were no differences between the densities of 1600 and 2200 stems ha^?1. Branches became thicker after early thinning, but the differences between the treatments were negligible for crop trees. Crown ratio was lowest as the result of early or moderate thinning (2200 stems ha^?1).     

绵阳官司河流域3种不同林分枯落物层储量及持水特性分析

对绵阳官司流域不同林分枯落物储量及持水量进行研究,结果表明：3种不同林分枯落物的储量顺序为松柏混交林（8.09t.hm-2）〉马尾松林（7.77 t.hm-2）〉柏木纯林（3.07 t.hm-2）,持水能力的大小顺序为柏木纯（3 709 g.kg-1）〉松柏混交林（3 392 g.kg-1）〉马尾松林（312 2 g.kg-1）,虽然林分不同,但在持水过程中均表现出相似性,即1 h前吸水量最大,并在2 h~4 h间达到较稳定的状态。各林分地表枯落物对降雨有效拦蓄量的大小顺序为马尾松林〉松柏混林〉柏木纯林。     

Effect of wide spacing on tree growth, branch and sapwood properties of young Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] in south-western Germany

The influence of stand density on Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] is conceptually understood, but for wide spacings not well quantified, particularly in Europe. This study used 41 trees from 7 different locations in south-western Germany to compare important tree- and branch-level attributes across three different densities, namely 100, 200, and 1,200 stems ha⁻¹. In general, there were only a few tree and branch attributes that were significantly different between the 100 and 200 ha⁻¹ densities. Crown projection area and diameter of the thickest branches were the most important differences between the 100 and 200 ha⁻¹ densities. The most obvious and significant differences in this study were between 100 and 1,200 ha⁻¹ densities, where nearly every examined tree and branch attributes were statistically significant. However, relative sapwood area, the number of branches, branch angle, and the occurrence of spike knots were insensitive to stand density. Although the two lowest stand densities in this study represent rather extremely wide spacings, these results still have important implications for the development of effective thinning regimes for Douglas-fir in south-western Germany. Important management recommendations from this study include thinned stands should be maintained to at least 200 stems ha⁻¹ to maintain high log quality and stand stability. Furthermore, even at stand densities exceeding more than 1,200 trees ha⁻¹ planted trees, artificial pruning may even be necessary to produce high quality logs.     

马尾松林分结构对枯落物层和土壤层水文效应的影响

[目的 ]通过监测不同林分结构马尾松林枯落物层和土壤层的水文效应,探究影响其效应的主要结构因子及相关关系,为马尾松林抚育经营管理提供参数。[方法 ]在三峡库区九岭头林场选取9块马尾松林样地,调查其林分结构参数,即叶面积指数、胸径、冠幅、角尺度、Margltf丰富度指数及林木竞争指数等,分别采用室内浸泡法和环刀法对枯落物层和土壤层持水特性进行定量研究,运用Pearson相关分析、主成分分析、冗余分析等方法分析林分结构对枯落物层和土壤层水文效应的影响及其相互关系。[结果 ]林木竞争指数、叶面积指数、林分密度与土壤最大持水量和枯落物层总有效蓄水量呈显著正相关(P<0.05),Margltf丰富度指数与土壤最大持水量呈显著正相关,而与枯落物层总有效持水量不相关。林分结构的变量组合分别解释了马尾松林枯落物层和土壤层水文效应的54.06%和61.80%。[结论 ]林分结构与枯落物层和土壤层水文效应密切相关,即林木竞争力越强,林木生长状况越好,林分蓄积量越多,枯落物层和土壤层的水文效应越好。     

不同间伐抚育强度对华北落叶松人工林林下凋落物的影响研究

文章以塞罕坝地区华北落叶松人工林为研究对象,主要研究在不同间伐抚育强度下其林下凋落物的现存量和持水量的变化情况。试验选取立地条件和成林状况基本一致的林分进行研究,设置弱度、中度、强度3种不同程度的间伐抚育强度与未间伐抚育林分进行对比研究,研究结果发现:伐后林分凋落物现存量表现为未伐(6.747t/hm2)弱度(6.209t/hm2)中度(5.121t/hm2)强度(3.922t/hm2),各林分持水量表现为未伐弱度中度强度,依次是2.527t/hm2、2.218t/hm2、1.690t/hm2、1.251t/hm2,且均是半分解层大于未分解层,平均持水量与凋落物现存量表现趋势一致。     

麻竹人工林水文生态效应

在福建南靖连续4a对1995年春在杉木采伐迹地上营造的株行距为3m×4m、4m×5m和5m×6m3种密 度的麻竹试验林进行水文生态效应观测。结果分析表明:(1)麻竹林冠截持量与降水量和林分密度均呈正相关,而 秆茎流和林内降水量与降水量呈正相关,与林分密度呈负相关。密度为825丛·hm-2的麻竹林的年林冠平均截持 量和截持率为155.2 mm和14．61％,林内平均降水量和降水率为829．0 mm和78．11％,竹秆茎流量和茎流率为 77.3mm和7.31％。(2)麻竹林地表枯落物具有吸持其自身干质量2．8倍水量的潜在能力。(3)3种密度麻竹林的 0-60 cm土壤层最大潜在蓄水量为315．3-326．3 mm,略低于毛竹林367．9mm。(4)麻竹林地表径流和泥沙流 失量与降水量呈正线性相关,与林分密度呈负相关;竹林密度为825丛·hm-2的麻竹林年地表平均径流量、土壤侵 蚀模数是密度为330丛·hm-2的麻竹林的0．55、0．45倍,其NO3-、NH4 、PO43-、K 等养分年流失量则分别是密 度为330丛·hm-2的麻竹林的0．58、0．49、0．36、0．49倍。     

Soil organic matter in European forest floors in relation to stand characteristics and environmental factors

Published data on the quantities of organic matter in the forest floor (SOM_fl) of European forest stands were collated. Studies of SOM_fl were included if the total sampled surface was at least 0.15 m², the surface of a single sample was at least 100 cm², live material was sorted out, and ash or carbon content was determined. Data from 59 forest stands were compared with regard to stand characteristics and environment. Using a single variable, tree genus was most important for the amount of SOM_fl (R ² _adj = 0.34). The amounts in spruce stands (41 × 10³ kg ha^?1) were significantly higher than those in larch, Douglas fir, oak and birch stands (4–11 × 10³ kg ha^?1). The best significant multiple model was genus combined with stand age and basal area (R ² _adj. = 0.72). The importance of litter quantity and quality for differentiating the tree genera is discussed.