筇竹天然林与人工林土壤养分及竹笋品质分析

筇竹是我国特有竹种,其笋味道鲜美营养价值高,具有较高的经济价值,近年来筇竹人工栽培面积不断增加。文章测定分析了四川省雷波县筇竹天然林和人工林的土壤养分状况以及竹笋营养物质含量,结果显示,筇竹天然林竹笋中的抗坏血酸含量和土壤中的有机质及含氮量均显著高于人工林,土壤中的有效磷和有效硅含量则显著低于人工林。与筇竹人工林相比,筇竹天然林的竹笋品质更佳,维生素含量更高;人工栽培筇竹可通过适度增加氮肥施入量、调节土壤中有效氮与有效硅的比例、增施有机肥等方法提高土壤肥力进而提升竹笋品质。     

桉树人工林土壤养分现状与施肥研究

我国华南地区桉树人工林土壤肥力的总体水平较低,氮、磷、钾缺乏且有效性较差,土壤吸水保水能力弱,淋溶严重,微量元素铜、锌、硼等也都普遍处在缺乏或极缺乏水平,以硼的缺乏最为突出。桉树基肥应以无机肥加有机肥施用为主,有机肥和无机肥都并非越多越好,要科学搭配。追肥只要是NPK的合理配比,都能增加产量。根据我国目前土壤肥力水平和经营现状,要获得并保持桉树人工林高产水平就必须大量施肥。施肥能少量增加木材纤维长度,显著增大纤维宽度,但并未降低木片基本密度,相反还略有增加,但差异很小。     

连栽对桉树人工林土壤养分含量的影响

采用时空序列和定位监测相结合的方法,对广西东门林场连栽桉树人工林土壤养分的变化情况进行了研究.结果表明连栽导致桉树人工林多数土壤养分含量不同程度的下降:(1) 土壤的pH值、土壤交换性Ca和速效K在0～20 cm和20～40 cm土层都有不同程度的降低,但不显著;土壤有机质、水解N和全K在0～20 cm土层显著下降,在20～40 cm土层,变化不显著;(2)全N在20～40 cm土层,显著下降,在0～20 cm土层变化不显著;有效P在0～20 cm和20～40 cm土层无显著变化,全P在20～40 cm土层显著上升;交换性Mg在0～20 cm和20～40 cm土层都显著下降;(3) 在0～40 cm土层,全N、水解N、交换性Mg显著下降,土壤pH值、有机质、全K、速效K及交换性Ca有不同程度的下降,但不显著.     

桉树人工林土壤养分效应及其评价

研究了桉树人工林的土壤养分效应,并通过改进的内梅罗(Nemerow)综合指数对土壤肥力进行了综合评价。结果表明:试验地林地土壤属于贫瘠水平,表土层A层土壤肥力综合指标值显著高于中土层B层;不同树种人工林土壤肥力存在着显著差异,依据综合肥力系数大小:柳桉>巨尾桉>赤桉>粗皮桉>巨桉;综合表明桉树人工林土壤养分效应呈正面效应。但由于多因素影响以及时间较短的缘故,而这种养分效应作用不显著。     

桉树人工林土壤呼吸与土壤养分关系研究

为探究桉树人工林土壤呼吸速率与土壤养分含量及其化学计量比之间的关系,本文以尾叶桉、粗皮桉、托里桉、赤桉、尾巨桉5个桉树林分及1个湿加松林分为研究对象,测定并分析土壤呼吸与土壤养分之间的关系。结果表明:土壤呼吸速率年均值为尾叶桉和托里桉林显著高于其他林分,其值分别为3.57±0.41μmol·m-2·s-1与3.72±0.20μmol·m-2·s-1,表现出空间异质性。土壤呼吸速率与土壤有机碳含量无显著相关性。土壤呼吸极小值与表层土壤C/P和N/P表现出显著正相关性。土壤呼吸与土壤化学性质之间的相互关系表现并不明显。     

杉木人工林土壤养分变化规律

该文从不同立地条件、不同发育阶段、不同密度管理和不同轮伐期4个方面具体阐述了杉木人工林土壤养分变化规律。指出:立地不同土壤肥力不同,立地条件越好,土壤养分含量越高;林分发育阶段不同土壤养分含量不同,幼龄林阶段,养分含量越高,中龄林时最低,成熟林时又有所回升;杉木林通过合理间伐,适当降低林分密度,可保持和提高土壤肥力;适当延长轮伐期有利于杉木林的养分归还。在对各种研究结果与结论作简要概括的同时,对当前研究工作存在的问题及今后研究的重点进行了讨论。旨在为今后的研究提供阶梯,以有助于各项研究工作的展开。     

高阿丁枫人工林土壤养分定位研究

采用灰色系统理论,对高阿丁枫人工林土壤肥力定位监测结果进行分析,得知：高阿丁枫人工林的土壤养分含量１９９３～１９９５年呈下降趋势,１９９５～１９９８年有所回升,但总的变化趋势是下降。其中,土壤有机质含量呈上升状态,有效Ｎ含量变化平稳,稍有上升,全Ｎ、有效Ｐ、有效Ｋ则呈下降趋势。因此,高阿丁枫人工林土壤养分含量下降的原因是土壤全Ｎ、有效Ｐ、有效Ｋ呈下降趋势。在高阿丁枫营林生产中,应考虑补充土壤中的Ｎ、Ｐ、Ｋ。     

用土壤养分系统研究法评价杨树人工林土壤养分状况

A study was conducted to evaluate the soil nutrient status of poplar plantation by Soil Nutrient Systematic Approach(SNSA) in Jianghan Plain, Hubei Province, China. Soil physiochemical properties were analyzed in laboratory through collection soil samples of study site. Ten treatments of application different fertilizers were designed such as CK, optimum treatment (N, P,K, Zn), -N(P, K, Zn), -P(N, K, Zn), -K(N, P, Zn), Mg(N, P, K, Zn, Mg), -Zn (N,P,K), 2P(N, 2P, K, Zn), 2K(N, P, 2K, Zn), and 2N 2P 2K(2N, 2P, 2K, Zn) for field experiment to test the effect on tree height, diameter (DBH) growth, and dry weight of poplar.The results showed that there was no significant difference in tree heights between treatments with different fertilizers, diameter growth of poplar trees in treatments of lack of N and Zn was significantly slower than that of trees in optimum treatment, and dry weight of poplar dropped significantly for treatment of CK as well as treatments without application N and Zn. It is concluded that N and Zn were main limiting factor for poplar growth. Results from laboratory analysis and field experiment were uniform perfectly, which proved that SNSA was reliable in evaluating soil nutrient status of poplar plantation.     

滇中高原云南松天然林和人工林土壤呼吸特征的比较

以云南磨盘山国家森林公园云南松天然林和人工林为研究对象,采用LI-6400-09便携式土壤呼吸室对土壤呼吸速率进行连续定位观测。结果表明:(1)两种林分的土壤呼吸速率具有明显的季节变化,均呈单峰曲线趋势;云南松天然林土壤呼吸速率在1.58~4.23μmol·m-2s-1之间,变异幅度为2.68;人工林土壤呼吸速率在1.13~3.34μmol·m-2s-1之间,变异幅度为2.96。(2)土壤呼吸速率的季节变化与不同层次土壤含水量均显著正相关(p0.05),而与不同层次土壤温度的相关性仅在云南松人工林达到显著水平。(3)双因素关系模型拟合结果表明,土壤温度和含水量共同解释了云南松天然林和人工林土壤呼吸速率的80.8%~93.0%和84.2%~85.9%。(4)两种林分土壤呼吸速率与土壤有机质含量相关性不显著(p0.05),土壤全氮含量仅与云南松天然林土壤呼吸相关性显著(R2=0.712,p0.05),而土壤水解氮含量对两林分土壤呼吸的影响均达到显著水平(p0.05),土壤C/N则与两林分呈极显著(p0.01)的负相关关系。因此,与天然林相比,人工林土壤温度、湿度及土壤C、N养分含量等土壤环境因子都存在变化,从而导致云南松天然林和人工林土壤呼吸速率时空变化的差异性。     

天然林择伐作业技术探讨

本分析了天然林合理择伐的各个技术要素的选择与确定，这些技术要素包括择伐方式，择伐强度，择伐周期，应伐木与保留木，采集方式等，为天然林择伐的具体实施提供理论依据。     

天然次生阔叶林转变为杉木人工林对土壤微生物量的影响

在我国南方,天然次生阔叶林转变为杉木人工林是一种常见的管理措施。为研究森林利用方式转变对土壤微生物量的影响,我们在中国科学院会同森林生态实验站比较了天然次生阔叶林、第一代和第二代杉木人工林土壤理化性质和微生物量。杉木人工林土壤有机碳、全氮、铵态氮和微生物量碳氮含量明显低于天然次生阔叶林。第一代、二代杉木人工林土壤微生物量碳仅为天然次生阔叶林的53%和46%,微生物氮为97%和79%。杉木人工林土壤微生物量碳占有机碳的比例也低于天然次生阔叶林土壤,但微生物量氮则相反,为杉木人工林高于天然次生阔叶林。因此可以得出,天然次生阔叶林转变为杉木人工林以及杉木林连栽引起了土壤生物学特性和土壤质量降低。图2表3参36。     

Microbial biomass in subtropical forest soils： effect of conversion of natural secondary broad-leaved forest to Cunninghamia lanceolata plantation

Conversion of natural secondary broad-leaved forest to Cunninghamia lanceolata plantation is a common management practice in subtropical China. In this study, we compared soil physico-chemical properties, microbial biomass in one natural secondary broad-leaved forest and two C. lanceolata plantation sites to estimate the effects of forest conversion on soil microbial biomass at the Huitong Experimental Station of Forestry Ecology, Chinese Academy of Sciences. Concentrations of soil organic carbon, total nitrogen, NH4^＋-N and microbial biomass carbon and nitrogen were much lower under C. lanceolata plantations as compared to natural secondary broad-leaved forest. Soil microbial biomass C in the first and second rotation of C. lanceolata plantations was only 53%, 46% of that in natural secondary broad-leaved forest, and microbial biomass N was 97% and 79%, respectively. The contribution of microbial biomass C to soil organic C was also lower in the plantation sites. However, the contribution of microbial N to total nitrogen and NH4^＋-N was greater in the C. lanceolata plantation sites. Therefore, conversion of natural secondary broad-leaved forest to C. lanceolata plantation and continuous planting of C. lanceolata led to the decline in soil microbial biomass and the degradation of forest soil in subtropical China.     

Forest structure and C stocks in natural Fagus sylvatica forest in southern Europe: The effects of past management

Managed forests often differ substantially from undisturbed forests in terms of tree structure and diversity. By altering the forest structure, management may affect the C stored in biomass and soil. A survey of 58 natural stands located in the south-westernmost limit of European beech forests was carried out to assess how the C pools are affected by the changes in tree structural diversity resulting from past management. The mean tree density, basal area and the number of large trees found in unmanaged forests were similar to those corresponding to virgin beech forests in Central Europe, whereas large live trees were totally absent from partially cut stands. Analysis of the Evenness index and the Gini coefficient indicated high structural diversity in the three stand types. The results of the Kolmogorov–Smirnov test used to compare the diameter distributions of each group revealed significant differences between stand types in terms of distributions of total tree species and of Fagus sylvatica.

The mean C stocks in the whole ecosystem – trees, litter layer and mineral soil – ranged from 220 to 770 Mg ha⁻¹ (average 380 Mg ha⁻¹). Tree biomass (above and belowground), which averaged 293 Mg C ha⁻¹, constituted the main C pool of the system (50–97%). The statistical test (Kolmogorov–Smirnov) revealed differences in the distribution of C pools in tree biomass between unmanaged and partially cut stands. As a consequence of the presence of large trees, in some unmanaged stands the C stock in tree biomass was as high as 500–600 Mg C ha⁻¹. In the partially cut stands, most of the C was mainly accumulated in trees smaller than 20 cm dbh, whereas in unmanaged stands the 30% of tree C pool was found in trees larger than 50 cm dbh. Furthermore, many unmanaged stands showed a larger C pool in the litter layer. The C content of mineral soils ranged from 40 to 260 Mg C ha⁻¹ and it was especially high in umbrisols. In conclusion, the implementation of protective measures in these fragile ecosystems may help to maintain the highly heterogeneous tree structure and enhance the role of both soils and trees as long-term C sinks.     

黑龙江省森工国有林区天保工程成就浅析

本文通过对管护经营责任制、森林覆盖率的提高、安置富余职工、产品结构调整、经济发展、社会稳定等方面的论述 ,分析了黑龙江省森工国有林区天然林保护工程取得的成就 ,指出了存在的问题。     

Effects of eucalypt residue management on nutrient leaching and soil properties

Effects of harvest residues on nutrient leaching and soil chemical properties were studied in a lysimeter experiment. Treatments were: (A) forest floor litter and harvest residues, other than branches, incorporated into the soil, (B) as A, but with branches cut in 20 cm long bits and placed on the soil surface, (C) as B, but with bits incorporated into the soil, (D) as B, but with branches chopped into chips, (E) as C, but with branches chopped into chips, (F) forest floor litter and harvest residues on the soil surface, with branches cut in 20 cm long bits, (G) as F, but with branches chopped into chips, and (H) absence of harvest residues (control). Treatments were applied in zero-tension lysimeters containing 25 kg of soil. Leachates were collected for a 6-year period. At the end of the experiment, lysimeters were dismantled and soil was divided in four layers. Residues, other than branches, increased N leaching, as compared with the control. Branches on the soil surface reduced N leaching when cut in chips. Branches incorporated into the soil reduced leaching independently of their size. Organic residues on the soil surface showed similar effect to those incorporated into the soil. However, harvest residues on the soil surface increased leachate volume, and reduced Ca and P losses. Such a placement of residues led to high contents of Ca and P in the 0–5 cm top soil layer. Contents of organic C, total N and base cations were not affected by the treatments.     

Loblolly pine growth and soil nutrient stocks eight years after forest slash incorporation

Incorporation of forest slash during stand establishment is proposed as a means of increasing soil carbon and nutrient stocks. If effective, the increased soil carbon and nutrient status may result in increased aboveground tree growth. Eight years after study installation, the impact of forest slash incorporation into the soil on soil carbon and nutrient stocks, foliar nutrients and loblolly pine growth are examined on mineral and organic sites on the North Carolina Lower Coastal Plain. Treatments include leaving forest slash on the surface and flat planting (control); V-shear and bedding (conventional), mulch forest slash followed by bedding (strip mulch) and mulch forest slash and till into the soil followed by bedding (strip mulch till). After eight years, mulching and/or tillage did not have a significant impact (p > 0.05) on soil bulk density or soil chemical properties (pH, cation exchange capacity, soil nutrients). Additionally, neither tree foliar nutrients nor stand volume were significantly impacted. However, significant effects were observed for soil phosphorus contents and stand volume between the control plots and the other treatment plots. For example, the mean stand volumes on the mineral site were 24.49 ± 1.28, 38.16 ± 2.90, 44.59 ± 3.07 and 46.96 ± 2.74 m³ ha⁻¹ for the control, conventional, strip mulch and strip mulch till plots. These observations are more likely due to the effect of bedding rather than mulching or tillage of the forest slash. These results are consistent for the mineral and the organic sites. Considering the greater expense to install the mulch and tillage treatments, the lack of a treatment effect on soil carbon and nutrient stocks and tree growth does not justify these treatments on these sites.     

The bird communities of a natural secondary forest and a Lophostemon confertus plantation in Hong Kong, South China

The avifaunas of a 30–40-year-old secondary forest and a 25–30-year-old Lophostemon confertus plantation were compared using the point count method over 1 year. Similar total numbers of bird species were recorded in the secondary forest (44 spp.) and the plantation (46 spp.) but many of those in the plantation were typical of non-forest habitats in Hong Kong and the number of forest-associated species was higher in the secondary forest. The mean total bird density in the secondary forest (44.5 ha⁻¹) was much higher than in the plantation (12.4 ha⁻¹). The Great Tit Parus major, Light-vented Bulbul Pycnonotus chinensis and Japanese White-eye Zosterops japonica were the three most abundant species at both the sites but their mean annual densities were all much higher in the secondary forest. There were relatively more granivores and insectivores and fewer insectivore-frugivores in the plantation. Twelve species were confirmed breeding in the secondary forest and none in the plantation.     

阿尔山林区人工林经营中存在的问题及对策

本文根据阿尔山林区实际情况，分析了阿尔山林区人工林生长规律及经营中存在的问题，并针对存在的问题，提出对策。     

Comparison of water quality in two catchments with different forest types in the headwater region of the Hun River,Northeast China

In the headwater catchments of the Hun River,Northeast China, secondary forests(SF) have been replaced by plantations since the 1960 s. Concern has been growing over this loss and the decline in water quality caused by the plantations. To test the effects of plantations on water quality, we selected two separate catchments covered by SF and Pinus koraiensis plantations(KP) to monitor physical and chemical properties of various hydrological variables including throughfall, stemflow,through-litterfall and runoff(flowing out of outlets of the catchments). The physical properties of water declined after water flowed through the two catchments as compared with rainwater. The pH of runoff in both catchments also dramatically decreased. The concentrations of Cl^-, NO_3^- and NH_4^+ in the runoff from the two catchments were similar(concentrations of Cl-and NH_4^+ in both catchments were similar to those in rainwater). Total P concentration in runoff of the SF catchment was higher than that of the KP catchment(P concentrations in both catchments were also higher than in rainwater) because P concentrations in litter and soil of the SF catchment were higher than those in the KP catchment. In summary, the rainwater became acidic in both catchments, but the responses of most water quality variables were similar in the two catchments, suggesting that appropriate ratios of KP in SF are feasible for secondary forest recovery and for preserving water quality(KP did not cause a decline in quality) in the headstream regions in Northeast of China.