种植方式对青海湖流域人工草地植被和土壤养分特征的影响

为探究多年生人工草地在青海湖流域的适应性和稳定性,本研究以青海草地早熟禾(Poa pratensis. Qinghai)和青海中华羊茅(Festuca sinensis. Qinghai)单播及混播人工草地为研究对象,分析不同种植方式下人工草地植被和土壤养分特征的变化。结果表明：青海草地早熟禾+青海中华羊茅混播草地和青海草地早熟禾单播草地的生物量和盖度高于青海中华羊茅单播草地,且在生长旺期(8月),青海草地早熟禾+青海中华羊茅混播草地生物量最高,为586.2 g·m^-2;青海草地早熟禾单播、青海中华羊茅单播和青海草地早熟禾+青海中华羊茅混播草地间土壤有机质、全氮、全磷、硝态氮、铵态氮和土壤含水量在相同土壤深度下差异不显著,但土壤氮、磷及有机质间存在显著的相关性。综上所述,在青海湖流域建植青海草地早熟禾+青海中华羊茅混播型人工草地可以获得较高的产量,但需在种植和管理过程中协调好土壤氮、磷间的关系。     

我国人工林生产力问题的研究（Ⅰ）—影响我国人工林生产力的自然因素评价

以桉树、杉木、马尾松、落叶松及樟子松等为对象 ,利用样地调查资料 ,结合已有研究成果 ,对造成我国人工林生产力低下的多种自然因素 ,进行了系统地分析研究。结果表明 ,按人工林现实分布格局及立地质量水平 ,全国人工林气候—立地生产潜力 (材积 )平均为 8 6m3 hm2 ·a ;现有人工林由于大面积幼龄林的存在 ,所带来的生产力总体水平下降的幅度为 31%～ 35 %。     

Spatial pattern and regeneration dynamics in a temperate Abies–Tsuga forest in southwestern Japan

This article reports the regeneration dynamics of a temperate Abies–Tsuga forest in Kirishima Yaku National Park, southwestern Japan, and examines the influence of species coexistence mediated by gap disturbances on biomass production. All trees taller than 2 m in a 1-ha plot were monitored over four growing seasons. Three growth-form groups occupied different vertical layers. Evergreen conifers and deciduous broad-leaved trees tended to be spatially segregated from evergreen broad-leaved trees, which formed thickets in the understorey. The regeneration of understorey evergreen broad-leaved trees was affected by canopy gaps. The recruitment of conifers and deciduous broad-leaved species was not observed during the four growing seasons. This suggests that regeneration is sporadic and the present environmental conditions are not favorable for these canopy species. The mortality and unsuccessful recruitment of conifers and deciduous trees appeared to cause fluctuations in the productivity of the stand. However, an abundance of canopy gaps accelerates the regrowth of shorter species, and the fluctuation of productivity resulting from the population dynamics of canopy species would be partly mitigated by the regeneration of evergreen understorey species. The horizontal and vertical heterogeneity of the temperate mixed forest was a result of the patch structures of the three growth-form groups. The different regeneration patterns among the three groups, which were driven by interactions of species-specific regeneration niches and disturbance regimes, might be an important factor in maintaining the aboveground productivity in a transitional mixed forest between warm-temperate and cool-temperate zones.     

四川盆地中山地带日本落叶松林分生产力研究

本文根据日本落叶松人工林林分蓄积量、生产力与林龄、立地条件、林分密度等因子的关系,选取21个样地,采用标准地调查、树干解析方法对其人工林的蓄积量、生产力以及与立地条件之间的关系进行了较为系统的研究。研究表明:日本落叶松人工林在四川盆地中山地带生长良好,林分生产力与林分所处立地条件、林分密度、经营管理等密切相关。     

Evaluation of Populus deltoides clones under nursery,field and agrisilviculture system in subhumid tropics of Central India

Populus deltoides Bartr., a native of North America, is generally grown in India above latitude 28 °N. One hundred and six clones were evaluated for four years at Raipur situated at 21°12N latitude and 81°36E longitude. These were grown on vertisol soil. Based on growth and survival performance in the nursery for two successive years, nineteen clones were selected for field evaluation. The best five clones (G3, G48, 65/27, D121 and S7C1) were planted in an agrisilviculture system at a spacing of 4 × 4 m with soybean grown as an intercrop. After 4 years these clones had an increment of DBH by 66.5 to 77.5% and of height by 42.2 to 78.6% within one year when compared to that observed at 3 years of age. In rank order of growth the best five clones were 65/27 > G3 > D121 > G48 > S7C1. Total biomass varied between 20.9 to 35.8 Mg ha^–1 in different clones. Among the tree components, stemwood accounted for 52–61% of the total biomass, followed by branches (20–25%), bark (9–13%) and leaves (7–10%). No significant variation between net primary productivity and photosynthetic efficiency was found in different clones. Soybean productivity decreased as the trees aged, reaching 40.5 to 58.1% in 4-year-old trees.     

Factorial analysis on forest canopy density restoration in the burned area of northern Great Xing＇an Mountains, China

The restoration of forest landscape has drawn much attention since the catastrophic fire took place on the northern slope of Great Xing‘an Mountains in 1987. Forest canopy density, which has close relation to forest productivity, was selected as a key factor to find how much the forest quality was changed 13 years after fire, and how fire severity, regeneration way and terrain factors influenced the restoration of forest canopy density, based on forest inventory data in China, and using Kendall Bivariate Correlation Analysis, and Distances Correlation Analysis. The results showed that fire severity which was inversely correlated with forest canopy density grade was an initial factor among all that selected. Regeneration way which did not remarkably affect forest canopy density restoration in short period, may shorten the cycle of forest succession and promote the forest productivity of conophorium in the future, Among the three terrain factors, the effect of slope was the strongest, the position on slope was the second and the aspect was the last.     

Influence of plantation site and wastewater sludge fertilization on the performance and foliar nutrient status of two willow species grown under SRIC in southern Quebec (Canada)

Salix discolor Mühl. (Sd) and Salix viminalis L. (Sv) were planted under short-rotation intensive culture (SRIC) on three unirrigated abandoned farmland sites with different drainage conditions, one well-drained (S₁) and the other two poorly-drained (S₂, S₃). One dose of dried and granulated sludge equivalent to 150 (T₁) kg of “available” N ha⁻¹ was applied to some plots in the spring of the second season while others were left unfertilized (T₀). The aims of the experiment were (i) to investigate plant response (growth and productivity) to plantation site conditions and sludge application; (ii) study nutrient status by foliar analysis. Over three seasons, growth in height and aboveground biomass were greater for S. viminalis than for S. discolor on all sites. S. viminalis planted on poorly-drained site 2 had the highest biomass yield (45.28 t ha⁻¹). Both species showed best height and diameter growth on poorly-drained sites. For both species, best performances were obtained on wastewater sludge fertilized plots. Comparative foliar analysis suggested that unfertilized sandy soil (S₁) and low foliar nitrogen concentration and content were limiting factors in the performance of the two species. Soil nitrate concentration increased as a result of sludge application. Heavy metal accumulation from sludge does not represent a risk to the environment. It was concluded that S. viminalis had the best productivity on clay sites, and that a moderate dose of dried and pelleted sludge (150 kg of “available” N ha⁻¹) may be a good fertilizer during the establishment of willows in SRIC, and may reduce nitrate leaching.     

淮北地区氮肥群体最高生产力水稻钾素吸收利用特征

以淮北地区有代表性的34个中熟中粳品种为试材,设置7个氮肥水平(0、150.0、187.5、225.0、262.5、300.0、337.5 kg hm~(–2)),得出各品种的最高产量,将该最高产量定义为氮肥群体最高生产力。在此基础上,明确处于顶层水平(≥10.50 t hm~(–2))、高层水平(9.75~10.50 t hm~(–2))、中层水平(9.00~9.75 t hm~(–2))和底层水平(≤9.00 t hm~(–2))水稻品种的钾素积累、分配及转运特征。结果表明,4个生产力等级水稻品种地上部植株、茎鞘和叶片的含钾率在拔节期最高;抽穗期顶层水平品种的这3个参数高于其他3个等级的品种;穗部含钾率差异不显著。随着氮肥群体生产力等级的提高,钾素总积累量增多;拔节前底层水平钾素积累量最多,两年平均为120.56 kg hm~(–2),比例占50.56%,顶层水平为最少,两年平均为108.02 kg hm~(–2),比例占35.99%;拔节至抽穗期和抽穗至成熟期顶层水平钾素阶段积累量及比例显著高于其他3个等级。移栽至拔节期,钾素积累速率为中层底层高层顶层水平,拔节后则为顶层高层中层底层水平。叶片的钾素转运量及转运率明显高于茎鞘;顶层水平叶片的钾素转运量高于其他3个等级,高层水平叶片的转运率最高;穗部增加量随生产力等级的递增而变大;抽穗到成熟期,茎鞘、叶片对穗的钾素转运贡献率表现为底层最高,中层次之,顶层最低。4个等级水稻品种籽粒生产率和百千克籽粒吸钾量差异不显著;钾素偏生产力和钾收获指数均表现为顶层高层中层底层水平。总之,氮肥群体最高生产力越高,水稻中后期植株钾素积累量及器官对钾素的吸收利用效率越显著。抽穗后保持较高的钾素吸收利用及转运效率是高产水稻品种的重要特征。     

立地条件和林分结构对有林地生产力的影响

通过分析有林地生产力与立地条件和林分结构中各因子的关系,探索制约有林地生产力的主要因素.结果表明:不同立地质量中Ⅰ类地单位蓄积量最高(268.86±20.24 m3/hm2),不同坡向中东坡单位蓄积量最高(269.78±38.54 m3/hm2),不同树种组成中10杉类型单位蓄积量最高(259.33±14.62 m3/hm2);有林地生产力与林分年龄、林分密度正相关,相关系数R分别为0.590、0.460;有林地生产力与海拔、坡度相关性不显著.以上结果说明立地质量、坡向和树种组成对有林地生产力影响显著;有林地生产力与林分年龄、林分密度相关,与海拔、坡度无关.     

Attributes of wheat cultivars for late autumn sowing in genes expression and field estimates

Due to the growing interest in Central and Eastern Europe on cropping of wheat in optional late autumn terms, called facultative, genetic research and field evaluation were taken on four spring cultivars: Tybalt (NL), Monsun (DE), Ostka Smolicka (PL) and Bombona (PL), currently being recommended by breeders. The PPD gene analyze, expression level of dehydrine genes (WCS120 and WDHN13) in cooling test, and qPCR for RNA isolation and analyses of WCS120 and WDHN13 gene expression at the BBCH12 stage of wheat were estimated. Molecular analysis of PPD-D1 gene confirmed the presence of photoperiod sensitive allele ppd-D1b in all tested genotypes. The highest level of NRE WCS120 gene was detected in cultivars Tybalt and Bombona. Two-year field experimental study assessed the growth, development and productivity of facultative and spring crops of studied cultivars. Based on our results from field experiments and result of molecular analysis of alleles of PPD-D1 gene, the tested genotypes can be considered as potentially facultative genotypes.