六盘山林区几种土地利用方式植被活体生物量C贮量的研究

通过野外调查测定,研究了六盘山林区天然次生林(杂灌林、山杨和辽东栎林)、农田、草地和人工林(13、18和25年生华北落叶松)植被活体生物量的C贮量.结果表明,天然次生林植被地上生物量C贮量为14.93～25.92 t·hm-2,根系为6.50～7.55 t·hm-2;人工林地上为11.97～45.39 t·hm-2,根系为6.48～7.64 t·hm-2;农田和草地地上分别为0.83和1.09 t·hm-2,根系分别为0.49和1.61 t·hm-2.植被活体生物量C年均积累量,天然次生林地上为2.97～5.15 t·hm-2·a-1,根系为1.67～2.86 t·hm-2·a-1;人工林地上为5.07～6.49 t·hm-2·a-1,根系为1.90～2.10 t·hm-2·a-1;农田与草地地上分别为0.83和1.09 t·hm-2·a-1,根系分别为1.38 和1.03 t·hm-2·a-1.在生长季,草本地上部分C积累呈逐步增长趋势,最高峰在9-10月,10月后下降.细根生物量C的积累量,天然次生林在5、6、9月较高,草地在8月份较低,农田在7和9月较高,人工林在5、9和10月较高.     

干旱风沙区营造人工柠条林对退化沙地土壤水分运动参数的影响

以宁夏盐池沙区退化沙地为研究对象,探讨其在营造人工柠条灌木林后,对土壤水分运动参数的影响,研究结果显示:退化沙地营造人工柠条林后,0～40 cm土层的土壤水分扩散率呈现增加的趋势;0～40 cm土层的土壤基质势明显低于对照天然草地;0～40 cm土层的土壤比水容量随造林密度的增加测定值降低;0～40 cm土层的土壤比水容量林地明显低于对照天然恢复草地;人工柠条林土壤非饱和导水率显著低于对照天然草地,其大小排序为天然草地>2 490丛.hm-2柠条林>1 665丛.hm-2柠条林>3 330丛.hm-2柠条林。     

嘉陵江上游低山暴雨区3种不同植被类型氮循环研究

本文通过对嘉陵江上游低山暴雨区不同植被类型的初步研究。不同植被类型的氮库总储量分别为：6 787.27 kg.hm-2、7 115.39 kg.hm-2、6 951.06 kg.hm-2。其中不同植被类型中活体生物量分别为：136.43 kg.hm-2、210.40 kg.hm-2、169.66 kg.hm-2,凋落物层分别为：31.06 kg.hm-2、38.96 kg.hm-2、40.05 kg.hm-2,土壤（0-40cm）中分别为：6 619.73 kg.hm-2、6 866.03 kg.hm-2、6 741.35 kg.hm-2。不同植被类型土壤中的氮分别占总储量的97.53%、96.50%、96.98%,活体生物量分别占2.01%、2.96%、2.44%,而凋落物层分别仅占0.46%、0.55%、0.58%。结果表明,低山暴雨区3种不同植被类型的N主要分布在土壤中,而在活体生物量和凋落物层中只占很少的一部分。3种不同植被类型树干径流的氮含量分别为：0.44 kg.hm-2、0.553 kg.hm-2、0.851kg.hm-2,林分穿透雨氮含量分别为：12.649 kg.hm-2、12.551 kg.hm-2、13.291 kg.hm-2,地表径流氮的输出量分别为：0.55 kg.hm-2、0.55 kg.hm-2、1.27 kg.hm-2。不同植被类型氮的生物循环：湿地松林吸收量、存留量、归还量、循环系数分别为：37.561 kg.hm-2.a-1、6.497 kg.hm-2.a-1、31.064 kg.hm-2.a-1、82.703%,刺槐林吸收量、存留量、归还量、循环系数分别为：48.976 kg.hm-2.a-1、10.019 kg.hm-2.a-1、38.957 kg.hm-2.a-1、79.543%,混交林吸收量、存留量、归还量、循环系数分别为48.127 kg.hm-2.a-1、8.079 kg.hm-2.a-1、40.048kg.hm-2.a-1、83.213%。吸收量、存留量均是刺槐林〉混交林〉湿地松林,归还量是混交林〉刺槐林〉湿地松林。结果表明,3种植被类型处于良好的养分积累状态,有利于系统的稳定持续发展。     

岷江干旱河谷-山地森林交错区典型人工林细根生物量及其碳储量特征

细根在森林生态系统的物质循环和能量流动中具有十分重要的和不可替代的作用.为了解岷江干旱河谷-山地森林交错带人工林生态系统功能,研究了该区青冈人工林(QF)、人工混交林(BF)、粗枝云杉人工林(SF)、沙棘灌木林(HP)和刺槐人工林(RP)五种典型森林群落细根的生物量及其碳储量特征.不同森林群落细根生物量和碳储量均随着土壤深度增加而降低,并与土壤发育程度和树种有关;细根主要分布土壤表层0～20 cm范围内,平均占细根总量的87%,大于20 cm细根也有分布,仅占细根总量的13%;QF、BF、SF、HP和RP细根的生物量分别为3 820 kg·hm-2、2 036 kg·hm-2、1 855 kg·hm-2、1 816 kg·hm-2和1 144 kg·hm-2,碳储量分别为1.91MgC·hm-2、1.02 MgC·hm-2、0.93 MgC·hm-2、0.91 Mgc·hm-2和0.57 MgC·hm-2.     

不同立地条件对飞播成苗的影响

以商洛市飞播林地为对象,通过调查、分析,研究了植被盖度、土壤类型和坡向对飞播造林成苗效果的影响,结果表明,不同植被盖度、土壤类型和坡向分别都会对飞播成苗面积比例和成苗地幼苗密度造成影响,植被盖度0.3～0.7,沙壤土和阴坡地的飞播造林成苗效果最好,它们二者在植被盖度为0.3～0.7时,分别是28.28%和2175株·hm-2,在沙壤土分别是32.6%和2631株·hm-2,阴坡地分别是38.5%和2 424株·hm-2;为取得最好的飞播效果,应选择一定的植被盖度范围、土壤类型和坡向。     

有机肥对沙地樟子松幼龄林、中龄林生长的影响

为探明有机肥对沙地樟子松生长的影响，在沙地樟子松幼龄林、中龄林连续4年进行带状沟施有机肥（生物炭、猪粪和牛粪），测量单株树高、胸径和材积。结果表明：不同配比的有机肥可以促进沙地樟子松幼龄林和中龄林树高、胸径和单株材积生长，幼龄林最佳施肥量为生物炭66.67 kg·hm-2、猪粪66.67 kg·hm-2、牛粪17.80 kg·hm-2，中龄林最佳施肥量为生物炭53.33 kg·hm-2、猪粪200.00 kg·hm-2、牛粪200.00 kg·hm-2。因此合理施肥能促进沙地樟子松幼龄林、中龄林的生长。     

吉林省西部地区苇塘鱼、蟹养殖试验

吉林省西部苏打型盐碱苇塘鱼、蟹养殖试验结果表明:鱼、蟹年平均产量为1 425.9 kg·hm-2和123.9 kg·hm-2,年平均经济效益1.591万元·hm-2,投入产出比平均为1.001.95;土壤含盐量年平均下降26.17%,土壤有机质含量年平均增加12.07%,全氮、全磷和全钾的含量平均提高55.06%、25.99%和29.86%;芦苇地表生物量年平均提高9.71%。该模式可在吉林省西部中低产苇塘的开发利用中推广应用。     

麻竹山地笋用林施用有机肥和生长调节剂的产量效应

对山地麻竹笋用林采用回归正交试验设计,施用有机肥和生长调节剂,分析研究了笋林的出笋量和经济效益.结果表明:不同处理麻竹林竹笋产量、挖笋数量、竹笋个体质量分别为11 451 ～25 440 kg·hm-2、7 840 ～15 360个·hm-2、1.41 ～1.66 kg·个-1;有机肥和生长调节剂对竹笋产量和数量的影响较为显著,竹笋产量和数量随有机肥施用量的增加而升高;经分析,竹笋产量、数量与施肥关系回归方程拟合良好;麻竹最佳施肥方案为有机肥2 484.8 kg·hm-2,生长调节剂用量为6.006 L·hm-2;竹笋最高产量的施肥量为有机肥2 482.35 kg·hm-2,生长调节剂用量为6 L·hm-2.各处理麻竹施肥收益的变化范围为-5 699.5 ～7 310.2元·hm-2,麻竹施肥对竹林经营收益影响显著,竹林施用有机肥和生长调节剂与竹林收益回归方程拟合良好.     

乌兰布和沙漠东北部土壤水分植被承载力

根据乌兰布和沙漠东北缘的自然环境特点和植物生理生态特征,基于水量平衡原理建立土壤水分动态模型,模拟计算该区植被在不同叶面积指数下的土壤水分动态变化和保证植物生存前提下的土壤水分亏缺值,评价该区土壤水分植被承载力.结果表明:自然条件下乌兰布和沙漠东北缘土壤蒸发占降水的比例在流动沙地和半固定沙地大于60%,固定沙地为44.8%;在叶面积指数低于1.7 m2·m-2时,土壤水分亏缺水平较低,叶面积指数继续升高时, 土壤水分亏缺大幅度增加.从而确定该区土壤水分植被承载力为叶面积指数1.7m2·m-2.     

川西南干热河谷地区引种巨尾桉人工林生态经济效果的初步研究

1999年 7月 ,从广西引进半年生巨尾桉组培苗 ,在攀枝花市仁和地区试种 34hm2 。测定结果 2 4年生巨尾桉林分的平均胸径为 6 1cm ,平均树高为 6 6m ,平均立木蓄积量为 32 33m3 ·hm-2 ;林分生物量及生产力分别为 2 5 85t·hm-2 和 10 77t·hm-2 ·a-1;林地枯枝落叶累积量及其最大吸水量分别为 7 11t·hm-2 和37 0t·hm-2 ,分别比草坡地高 2倍～ 5倍 ;林地土壤 (0～ 4 0cm)容量为 1 36g·cm-3 ～ 1.4 5g·cm-3 ,比草地略低 ;土壤总孔隙度及通气度分别为 5 1 2 9%～ 6 2 32 %和 19 5 5 %～ 2 6 38% ,分别比草地略高 ;土层最大、毛管及最小持水量分别为 34 93%～ 4 5 31%、31 5 4 %～ 39 82 %、2 1 94 %～ 2 6 32 % ,相应比草地略高 ;林内日平均气温及日较差分别为 2 2 2℃～ 2 3 1℃和 4 4℃～ 8 9℃ ,分别比草地低 0 2℃～ 2 4℃ ;林内空气相对湿度日均值为 80 %～ 88% ,比草地高 3%～ 16 %。初步显示出巨尾桉人工幼林的生态经济效益     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.