集水造林不同密度林分生长研究

在黄土高原 ,集水造林与常规造林相比 ,林木的生长规律和林分的生产力水平有显著的差异 ,其产生的根本原因是集水造林通过增加植树带汇流量改善了林地土壤水分条件。通过对 4种密度 (84 0、1110、2 2 2 0和 3330株·hm- 2 )自然坡面集水造林的 15a生刺槐林及拍光坡面集水造林和常规造林 (密度同为 10 0 0株·hm- 2 )的 9a生刺槐林进行研究 ,表明林分密度越小 (集水面积越大 ) ,微型集水区产流率越高 ,则植树带汇流量越大。以密度为 84 0株·hm- 2 的林分植树带汇流量为 10 0 %计 ,则从小到大其余 3种密度的林分植树带汇流量分别占 93 6 0 %、81 77%和 84 4 3% ,密度最小的林分年均土壤含水率比密度最大的 2林分高约 2 0 %～2 5 % ;集水造林比常规造林植树带年汇流量多 30 %左右 ,土壤水分相差约 10 %。由于水分条件的差异和密度效应 ,各密度林分间及集水造林和常规造林间的树高、胸径和材积生长量差异显著 ,尤其生长总量最为明显 ,从小到大 4种密度林分 15a时树高分别为 12 10、10 31、8 4 5和 7 2 2m ,胸径分别达到 17 14、11 6 1、9 17和6 5 6cm ,林分蓄积量分别为 2 14 5 8、110 2 9、12 1 35和 84 0 3m3·hm- 2 ;集水造林和常规造林 9a时的树高生长分别达到 9 13和 7 0 4m ,胸径生长分别达到     

集水造林防止人工林植被土壤干化的初步研究

本文对采用集水造林措施的两种密度人工刺槐林的产流、土壤水分变化、水量平衡以及林木生长情况与常规造林进行了对比分析,结果表明集水造林能增加植树带径流收获量,提高土壤含水量,使更多的降水渗入到根际区以下的深层土壤,防止了土壤水分长时间持续严重亏缺———土壤干化的发生,以及所导致的林木生长不良等问题。其中,以密度较小的８ｍ２拍光处理的效果最佳,生长季汇集径流量的２０％以上将贮留于土壤中,有效地补充了深层土壤水分,促进了林木生长。     

黄土高原坡面林地不同集水措施对林木光合速率的影响

对山西省方山县峪口镇半干旱山区坡面的刺槐、白榆人工林木的光合速率和叶绿素含量受不同造林措施的影响而变化的规律进行了研究。结果表明,采取一定的集水措施——拍光坡面和在拍光的坡面上喷有机硅以防止雨水渗入而使较多的雨水流入植树穴内,可以有效地提高该地区林木的光合速率和叶片中叶绿素的含量。林木光合速率的变化趋势为:坡面喷有机硅>坡面砸实拍光>自然坡面。经有机硅集水的林木叶绿素含量均高于自然坡面。刺槐提高25%,白榆提高11%。降雨之后效果更为明显,尽管叶绿素含量均明显提高,如自然坡面,刺槐提高11.4%,白榆提高32.5%,但喷有机硅坡面的更为显著,刺槐提高19.2%,白榆提高45.2%。     

松华坝水源区森林微集水区降雨与径流过程分析

微集水区是山区最基本的水文单元,其降雨产流特征研究可以为流域水文的规律研究提供重要的数据支持。针对迤者小流域的森林微集水区进行不间断观测,得出结论:降雨量直接影响微集水区的径流产生量,7月19日24h内降雨量为36.6mm,降雨性产流105.57m3;径流洪峰一般滞后于降雨量峰值,7月19日降雨—径流监测中,最大产流值滞后最大降雨量值2h50min。     

豫南山区典型森林类型径流变化规律研究

采用连续定位观测的研究方法和小集水区技术,对豫南低山区针阔叶混交林等4种林型径流变化规律进行了研究。结果表明,落叶阔叶林、针阔叶混交林、毛竹林以及杉木林等4种林型均具有较强的涵养水源和保育土壤功能,坡面径流系数在1.06%～3.20%之间,土壤侵蚀强度均为微度侵蚀。坡面径流总量,落叶阔叶林〈针阔叶混交林〈杉木林〈毛竹林;水土流失量,针阔叶混交林〉落叶阔叶林〉毛竹林〉杉木林。4种林型坡面径流量与1次降雨量均存在显著的幂函数曲线回归关系,曲线回归相关系数分别达到0.886、0.919、0.913、0.868。针阔叶混交林小集水区年总径流量为547.19 mm,径流系数为34.8%,其中地下径流为498.39 mm,坡面径流仅为48.80 mm;月径流总量与降水量、蒸发量均存在显著的回归关系,可分别用幂函数和指数函数曲线式表示,曲线回归相关系数分别达到0.969、0.758。     

滇中华山松人工林的水文特征及水量平衡

根据滇中高原的华山松林集水区径流场连续 3a的降雨和径流观测数据 ,进行了华山松人工林的水文特征及水量平衡的研究。结果表明 :( 1)本区域降水量的季节分配不均 ,湿季 ( 6～ 10月 )降水量占全年的 80 % ,降水量主要由大于 10mm以上的降雨带来 ,且降雨强度大部分小于 5.0mm·h- 1。 ( 2 )集水区年平均降雨量 10 0 5.6mm ,在林冠作用面降雨量的分配中 ,林冠截留雨量 2 10 .6mm ,截留率 2 0 .9% ;穿透过林冠层的降雨 74 5.3mm ,树干茎流量 4 9.7mm ,分别占降雨量的 74 .2 %和 4 .9%。 ( 3)集水区径流的月变化滞后于降雨 ,总径流量 172 .2 9mm ,总径流系数 17.13% ,其中 ,地表径流 8.0 3mm ,地下径流 164.2 6mm ;地表径流主要集中在雨季产生 ,一次性降雨对地表径流的影响显著 (R =0 .91)。 ( 4 )土壤蓄水年变化量 11.2mm ,约占年降水量的 1.1% ,但月变化较大 ;系统水量最大的输出是蒸散 ,每年以气态形式返回大气的水量 82 2 .1mm ,占降水量的 81.8% ;在蒸散的水量中 ,林冠截留雨量的直接物理蒸发量 2 10 .6mm ,占总蒸散量的 2 5.6%。     

黑龙江西部低山丘陵坡面集水工程抗旱造林试验

选取4种不同的坡面集水处理(覆膜、撒水泥、刨光、自然坡面)措施,开展了不同坡面集水措施对造林效果影响的试验。结果表明:不同坡面处理措施对土壤含水率、造林成活率及林木生长产生不同影响,其中撒水泥处理措施土壤含水率最高,覆膜处理措施造林成活率最高,且苗木生长效果最好。     

大青杨、银中杨及三角叶杨的繁育技术

杨树以其生长快、成材早、适应性强、木材用途广 ,而成为我国的主要栽培树种。杨树品种繁多 ,根据适地适树的原则 ,我们对小兴安岭主要原料林造林树种大青杨、银中杨、三角叶杨进行了繁育试验 ,以便选育出适合朗乡地区的杨树新品种。1　试验地概况试验地选在黑龙江省朗乡林业局英山苗圃 ,地理坐标为 4 6°5 2′N ,12 8°4 8′E ,海拔高度为35 0m ,地下水位 1 6m ,土壤耕作层 2 5cm ,pH值为 5 6 ,年降水量 6 0 0～ 80 0mm ,无霜期为10 0天 ,≥ 10℃有效积温在 2 0 0 0～ 2 2 0 0℃之间 ,相对湿度在 70 %左右 ,年平均气温 - 0 5～0 5℃。…     

间伐强度对云南松中龄低产林分结构的调整研究

2008年通过对禄丰村林场徐家山林区具有代表性的25 a生塘播云南松人工用材林进行本底调查,依据云南松的林分密度、林木平均胸径、云南松单株林木平均占据的面积和云南松的枯立木百分比等判断该林分为云南松的劣质低产用材林,确定抚育间伐是该林分改造的主要措施。选择相似立地条件的林地,在同一坡向(SE)分别以1 hm2为间伐单位,设置4个研究区,分别设为3块样地及1块对照样地,以研究区内原有林木株数控制进行间伐,间伐的强度样地分别为40%(样地1)、30%(样地2)、20%(样地3)和0%(对照),每个研究区选择林木生长均匀的900 m2(30 m×30 m)作为长期调查研究的标准样地。间伐结束进行第2次调查,1年后进行第3次调查。结果表明:处理1～3间伐前后林木胸径与对照相比,无论其平均值、最小胸径或林木的胸径集中分布范围的下限,均得到了明显的提高,胸径分布较为均匀。云南松的林分质量也相应的得到了提高,达到了间伐的效果。对照样地仅实施下层灌草清理和对部分天然更新的阔叶树伐除,故其云南松林木株数的胸径仍呈左偏态分布,胸径分布极不均匀,林木胸径的分布仍处于自然松散的状态。云南松间伐后,不但林木的胸径得到了普遍的提高,其平...     

香梨栽培技术要点

1　严把苗木栽植关 ,确保果园的整齐1.1　选择好授粉树种 ,授粉树种配置应不低于 2 0 % ,生产实际中一般多采用 5∶ 1栽植 ,授粉品种建议选用金二十世纪、新世纪。株行距 5m× 3 m定植。定植时间为 3月底～ 4月初。1.2　挖大坑 ,栽壮苗。新植梨园对新垦荒地、贫瘠土地要挖 0 .8m×0 .8m× 0 .8m的栽植坑 ,将表土和底 (心 )土分别摆放坑两侧。先将一部分表土填入坑底 ,再按每株有机肥 10 kg或 2 kg油渣同心土均匀混合填入 ,最后再填约 2 0 cm的表土 ,填至距地面约 2 0 cm。较肥沃的熟地 ,可挖 0 .6m× 0 .6m× 0 .6m的栽植坑 ,其方法同上。定…     

尖山河流域不同植被类型坡面产流产沙量研究

对云南省玉溪市小尖山流域径流小区进行定位观测试验,对珠江石灰岩溶地区的不同植被类型坡面产流产沙量进行分析,结果表明：①该小流域降雨量年内分配不均,雨季（6—9月）占全年降雨量的83．2％,当降雨量大于5mm或10min雨强大于9mm／h时都会使该流域坡耕地发生产流．②灌草丛和次生林比坡耕地减少产流54．29％和92．06％,比人工林减少产流52．78％和87．13％．4个径流小区的产流大小顺序为：坡耕地〉人工林〉退耕地-灌草丛〉次生林．③土壤侵蚀量随着径流量的增加而增加,灌草丛和天然次生林分别比坡耕地减少土壤侵蚀量95．96％和99．02％,比人工林减少土壤侵蚀量64．60％和91．40％,其大小顺序与产流量一致．坡耕地、人工林、灌草丛的侵蚀量主要是由几次单次侵蚀贡献的,而次生林则是平均贡献．因此次生林防止水土流失的效果最好,在建立人工林时,应该考虑合适的复层结构,乔灌结合才能达到水土保持的最佳效果．     

人工降雨条件下毛竹林地表枯落物固土防蚀效应

对长江三角洲森林生态定位站北亚热带次生毛竹林枯落物水土保持功能进行了模拟研究。结果表明:(1)在室内人工模拟降雨条件下,坡度和雨强是影响坡面侵蚀的重要因素,随着坡度和雨强的增大,泥沙浓度也不同幅度的增大;(2)坡度为5°、10°、15°、20°、26.5°时,裸露坡面和覆盖凋落物的坡面比较,随着坡度增加,覆盖有枯落物的泥沙浓度增幅明显减小,且减少幅度为52.9%～87.1%;(3)在室内人工模拟降雨条件下,雨强为10～50mm/h时,有枯落物覆盖的土壤侵蚀量比裸露坡面分别减少35.58 g/m2、66.82 g/m2、130.32 g/m2、190.62 g/m2和256.16 g/m2。覆盖凋落物的坡面径流量增大幅度相比裸露坡面低25%左右。因此,毛竹林地枯落物可以减少水土流失,有较好的保水保土作用,对控制水土流失有显著效果。     

不同密度杉木幼林系统生产力和生态效益研究

杉木幼林系统是由４个不同密度级处理系列小区组成,栽植密度为１６６５、３３３０、４９９５和６６６０株／ｈｍ＾２（以下分别用Ａ、Ｂ、Ｃ和Ｄ代替）。这些小区土壤质地及地形别无二致,都是用１年生实生苗１９８７年春天定植。８年生时调查了这些幼林系统林木生长、冠层厚度、枝下高以及生态效益等。随着密度由Ａ增加到Ｄ：平均胸径生长量从８．１ｃｍ降到６．６ｃｍ;平均树高生长量由５．９ｍ降至５．４ｍ;平均冠层厚度自４．     

稻草编织物覆盖对坡耕地红壤水土流失的影响

通过自然降雨条件下的径流小区试验,研究了水稻编织物在坡耕地红壤水土流失控制上的作用.结果表明:稻草编织物覆盖能有效地减少水土流失,稻草编织物覆盖的小区径流量为697.67 m3,侵蚀量为6.44 t/hm2,而无覆盖的小区产生径流量为1 728.19 m3,侵蚀量为111.98 t/hm2,径流量是覆盖处理的2.48倍,侵蚀量是覆盖处理的17倍.降雨因子与径流量及侵蚀量的关系研究表明:雨强越大,径流量就越大;雨强大也导致侵蚀量增加;侵蚀量不仅与径流量有关,还与人类活动相关.     

梁山慈竹在退耕还林中的水土保持效应研究

利用小型径流观测场对比观测降雨时间集中的梁山慈竹林和未退耕种植红薯的耕地的17次降雨、10次水土流失过程进行效益对比,分析侵蚀量、径流量与降雨因子的关系。结果表明,退耕还梁山慈竹林的穿透降水率为89.14%,茎流率平均为1.57%,林冠截持降水率为9.29%;凋落物层的最大持水量约为27.54 t.hm-2,相当于水深2.4～3.3 mm,占降水量的14.46%～19.88%;与未退耕地相比,梁山慈竹林的平均径流量比耕地减少24.6%,而耕地侵蚀量约是林地的4.7倍,林地降水的泥沙侵蚀平均减少量达到78.56%。梁山慈竹有较好的水土保持作用,能够明显地减少地表径流和泥沙侵蚀。     

Characteristics of runoff and sediment generation of forest vegetation on a hill slope by use of artificial rainfall apparatus

We studied the impact of forest vegetation on soil erosion,surface runoff, and sediment generation by using field simulated rainfall apparatus. We measured runoff and sediment generation of five 4.5 × 2.1m runoff plots (a bare soil as a control; two Pinus tabulaeformis forestplots and two Platycladus orientalis forest with row spacing of 1 m × 1m and 1.5 m × 1.5 m, respectively) in Beijing Jiu Feng National ForestPark under three rainfall intensities (0.42, 0.83, 1.26 mm per minute).Forest vegetation significantly reduced soil erosion and sediment yield.Mean total runoff volume in the four tree stand plots was 93% of that inthe control plot, demonstrating the limited effectiveness of forest vegetation in runoff control. With increasing rainfall intensity, runoff reductionin forest plots declined from 28.32% to 2.1%. Similar trends in runoff coefficient and the relationship between runoff volume and rainfall duration was observed. Mean total sediment yield and mean sediment yield reduction rate under different treatments was 55.05% and 43.17% of those in the bare soil control plot, respectively. Rainfall intensity playedan important role in runoff and sediment generation processes, and had agreater impact on runoff than on soil erosion and sediment generation.When considering several factors in runoff and sediment transport processes, the P. tabulae form plot with row spacing at 1 × 1 m had a greater effect on soil and water conservation than did other forested plots.     

Local and regional environmental variation influences the growth of tropical trees in selection trials in the Republic of Panama

Native Neotropical trees are being increasingly planted for restoration purposes and timber production, but we lack species-specific data on growth responses to different regional climates and local environmental variation. We used regression trees and variance components to quantify the effects of within- and among-site environmental variation on the basal area (BA) of 21 Neotropical and two exotic tree species at three selection trials in the Republic of Panama. Sites represented distinct regional climates in which annual rainfall varied from 1100 to 2226 mm, with dry seasons of 4.1–6.7 months. Local environmental variables included measures of slope steepness and position, soil texture, soil color, and indicators of soil condition, such as subsoil rockiness.     

林地径流调控工程抗旱能力及效益研究

半干旱区降雨不足、供需错位,导致林木供水不足,造成土壤干化、植物生长发育困难甚至衰败,林地径流调控工程技术的发展为解决上述问题提供了技术支撑.对安定区退耕还林、荒坡林地径流调控工程林草生长量及后续土壤水分进行了调查分析,结果表明:2010～2011年遭遇10个月旱灾后,同等林木需水量设计的隔坡水平阶径流调控工程,2m土...     

Effects of foliage and traffic intensity on runoff and sediment in skid trails after trafficking in a deciduous forest

After ground-based skidding operations, soil particles are rearranged closer together resulting in increased bulk density, reduced total porosity, and decreased infiltration capacity. The aim of the present study was to assess and quantify runoff and sediment in both leafed and leafless periods (foliage) over a 1-year duration following three levels of skidder traffic intensity (low, medium, high) performed in the Hyrcanian forests, Iran. By increasing traffic frequency, soil bulk density increased significantly, whereas total porosity decreased as compared to undisturbed (control) plots. After trafficking, runoff and sediment yield were significantly affected by foliage and traffic frequency. Regardless of foliage, mean total runoff and sediment increased with increasing traffic frequency performed on the skid trail. Mean runoff in the low, medium, and high traffic plots in the leafless period were 95.5, 54.2, and 21.7% higher than the values of runoff in the leafed period, respectively. Mean sediment yield in the low, medium, and high traffic plots in the leafless period was 7.1, 5.1, and 3.3 times higher than the values of sediment in the leafed period, respectively. Based on regression analysis, the runoff and sediment response to rainfall for the control plots and three traffic intensity classes were linear and statistically significant for both leafless and leafed periods. The total runoff in the high traffic intensity plot was 239.8 mm (62%) during the leafless period, and 38% of total runoff (148 mm) occurred during the leafed period. The sediment response to runoff over both leafless and leafed periods at all the traffic intensity classes and control plots were significantly linear. Restricting ground-based skidding operations to trail segments where the machine traffic is less than 4 (low)—9 (medium) traffic cycles can be effective to reduce runoff and sediment over compacted soil after machine-induced traffic.     

Using multi-source remote sensing data to classify larch plantations in Northeast China and support the development of multi-purpose silviculture

Due to increasing timber demands, large areas of secondary forests have been converted to larch plantations(LPs) in Northeast China because the secondary forests could not produce timber as much as LPs.However, there are a series of ecological problems such as lower soil fertility, reduced water-holding capacity and acidification of surface runoff water occurring in LPs because of the single-species composition of LPs.Therefore, a guidance on how to transform LPs into larch-broadleaf mixed forests(LBMFs) at a large spatial scale is needed for local foresters.First, Landsat time series data set and SPOT-5 images were combined to map the spatial–temporal distribution of LPs in Northeast China.Then, the topographical characteristics of LPs in 2010 s were determined.Furthermore, three sub-regions of LPs were divided closely linking to their ecosystem services and forest management aims.Finally, detailed information on how to transform the LPs into LBMFs was given according to the three subregions.The results showed that the area of LPs increased during 1980 s and 2010 s, and reached 2.61 million ha in2010 s.Of which, 0.72 million ha(27.6%) and 1.89 million ha(72.4%) LPs distributed in slopes less than 5° and greater than 5°, respectively.Of the LPs(72.4%) in slopes greater than 5°, 48.7 and 23.7% located in downslope(LPs locating at the down slope of adjacent secondary forests in the same aspect) and upslope(LPs locating at the up slope of adjacent secondary forests in the same aspect), respectively; 0.10 million ha(3.8%) located in slopes greater than 25°.The LPs were divided into Sub-Regions-Ⅰ, Ⅱ, Ⅲ according to slopes.For Sub-region-I(top role is to produce timber), self-fertilizing shrub species can be introduced after clean cutting for young-aged LPs, and release thinning can be applied for middle-aged LPs, fast growth thinning for near-matured LPs, and clear cutting for matured LPs.For Sub-Region-Ⅱ(the priority is to provide water conservation combined with timber production), the LPs should be induced into LBMFs.The LPs located the downslope positions in Sub-Region-Ⅱ can be transformed to LBMFs by natural regeneration of broadleaved tree species after thinning because of enough seed sources of broadleaved tree species from the secondary forests locating the upslope positions.The LPs located the upslope positions or the region where seed sources of broadleaved tree species are unavailable in Sub-Region-Ⅱ must be induced to LBMFs by artificial regeneration.For Sub-Region-Ⅲ(the preference is only for water conservation because the slope is greater than 25°), the LPs should be particularly protected from intensive disturbances, and induced into LBMFs by natural regeneration.