林业苗圃杂草种群结构的研究

林业苗圃杂草种群结构的研究结果表明:苗圃地的杂草种群结构受环境条件的影响,不同的覆盖物、不同的时期杂草种群的结构有所差异;苗圃杂草种群的形成有一定的规律,遵循S型曲线的变化规律;杂草种群个体数量的高发生期在10 d左右,一般在6月中旬大量发生;播下林木种子后,立即施用除草剂,能够有效地控制杂草种群,缩短杂草的大量发生期限。     

Soil solarization in an Italian forest nursery

A 2-year field and laboratory study on double-layer solarization in a forest nursery was carried out. The efficacy of controlling soil-borne Pythium spp., Fusarium spp. and Rhizoctonia solani is discussed.     

Extractable sulfate content in Japanese forest soils

The amounts of extractable sulfate in 12 forest soils were measured as a preliminary work to study sulfur dynamics in forest ecosystems. The sulfate content determined by the distillation method varied widely (10–880 × 10⁻⁶ gSg⁻¹) depending on the soil type and the depth. Japanese forest soils were broadly divided into two groups in sulfate level: one retains a large amount of sulfate and the other does not. In general, the surface soils to the depth of 10 cm contained small amounts of sulfate (< 100 × 10⁻⁶ gSg⁻¹), while subsoils contained more. The soil samples with low (< 4.6) or high (6 <) pH (H₂O) retained small amounts of sulfate. Black soils derived from volcanic ash retained great quantities of sulfate. The two levels of sulfate contents in Japanese forest soils suggests that the sulfur dynamics are different in these soils.     

Results from six Pinus taeda nursery trials with the herbicide pendimethalin in the USA

Pendimethalin is used by some nursery managers to control weeds in Eucalyptus and Pinus seedbeds and cutting beds of Pinus. Six trials were implemented in open-rooted seedbeds to test the response of Pinus taeda to postemergence (to the crop) applications of 2.2 kg ha^?1 active ingredient of pendimethalin (the formulation contained 455 g l^?1). No stunting was noticed when treating seedlings with 2.2 kg ha^?1 four to 10 weeks after sowing. In one study, treated seedlings were larger than those not treated. Although the 2.2 kg ha^?1 rate provided good control of the prostrate weed Chamaesyce maculata, pine seedlings developed herbicide galls on the stem near the groundline. The frequency of herbicide galls at 2.2 kg ha^?1 varied by study and ranged from 0 to 28%. At present, it is not known if the frequency of gall formation depends on environmental or genetic differences.     

Relating sulfate adsorption to soil properties in Japanese forest soils

The relationship of sulfate adsorption capacity to the presence of aluminum, iron oxides, and organic carbon in four Japanese forest soils was investigated. Sulfate adsorption capacities were higher in subsoils than in surface soils, and their profiles were the inverse of those of organic carbon content. The black soil derived from volcanic ash had high sulfate adsorption capacity and showed no release of sulfate, while some of the surface horizons of the other soils desorbed sulfate. Oxalate extractable aluminum (Al₀) and iron (Fe₀) and ditionite-citrate-bicarbonate (DCB) extractable iron (Fe_d) were positively correlated with the sulfate adsorption capacity, and their correlation coefficients were almost identical (0.58–0.61). The lack of significant correlation between Al_d and the adsorption capacity suggests that DCB is unsuitable for extracting aluminum compounds which have the ability to adsorb sulfate. In contrast with oxides, organic carbon correlated with sulfate adsorption capacity negatively, and had a negative coefficient in a multiple regression equation, insignificantly. Furthermore, H₂O₂-treated samples containing decomposed organic matter adsorbed more sulfate than untreated samples. These results clearly indicated that organic matter hinders sulfate adsorption. A comparison of theβ value (standard regression coefficient) of organic carbon with that of Al₀ showed that the negative contribution of organic matter to sulfate adsorption capacity was slightly less than the positive contribution of oxides.     

Incorporation of slow-release fertilisers into nursery media

Field application of fertilisers is frequently ineffective in supplying limiting nutrients during establishment of plantation trees in highly weathered soils in the humid tropics. An alternative strategy for more effective delivery of nutrients to establishing trees was investigated in a field experiment on Kolombangara in the Solomon Islands. Under routine operational nursery conditions, cuttings of Gmelina arborea and seeds of Acacia mangium were planted into a coir (composted coconut husks) potting medium to which a range of rates of slow-release fertilisers had been applied. The growth performance of this nursery stock was then measured during the first 14 months following planting in the field. Incorporation of slow release fertilisers into the nursery medium significantly improved the growth of both species in the field, with more than 100% increases in volume index associated with the highest rates of slow release fertiliser application. This strong nutrient response during tree establishment was in sharp contrast to the absence of any effect from much higher rates of surface applied fertilisers that had been observed in previous field experiments on this same soil type. The placement of the slow release fertilisers within the immediate proximity of roots of the establishing trees, and the subsequent effects of this in increasing their abilities to compete with regrowth vegetation for site nutrient resources probably accounted for the high effectiveness of this fertiliser strategy in enhancing tree growth.     

Management of forest nursery soils dominated by calcium salts

Soils that contain high levels of calcium salts can affect tree seedling growth in two ways: high total salts can reduce water availability, and excess calcium can affect seedling nutrition. Nutritional problems, such as iron deficiency (lime-induced chlorosis) and phosphorus deficiency, can seriously affect forest nursery production through growth losses, stunting, and sometimes seedling mortality. High calcium soils can be diagnosed by visible symptoms, soil tests, and seedling nutrient analysis. Soil management practices that have been used to treat high calcium soils include site selection and soil mapping, species and stock type selection, fertilization, and soil acidification. Cultural practices, including irrigation, mulching, deep ripping, organic matter amendments, and mycorrhizal treatments, have been used to lessen the adverse affects of high calcium soils.     

Soluble organic nitrogen in forest soils of northeast China

Soluble organic nitrogen (SON) is recognized as a sensitive indicator of soil nitrogen status. The present work was conducted in the temperate forests of northeast China where soils are typically characterized by high organic matter and high organic nitrogen content, and soil sampling was made in early spring just after the freeze-thaw period. The water extracted SON pools in the organic layer of forest soils were measured within the range from 156.0 mg·kg-1 to 292.6 mg·kg-1, a similar magnitude of salt solution extracted SON pools reported in literatures. However, the water soluble SON pools in 0-15 cm mineral soils in present study were much higher (3-10 times) than any other reports, ranging from 58.6 mg·kg-1 to 125.2 mg·kg-1. Water soluble SON varied markedly among the soils under different forests and at different sites. The SON in water extracts were positively and significantly correlated to soil organic matter and total nitrogen contents, but negatively correlated to microbial biomass nitrogen (MBN). The reasons of the abnormally large SON pools and the negative correlations between SON and MBN in the 0-15cm mineral soils in this study were specially discussed.     

Root-associated fungi of healthy-looking Pinus sylvestris and Picea abies seedlings in Swedish forest nurseries

The aim of this study was to assess fungal communities in roots of healthy-looking Pinus sylvestris L. and Picea abies (L.) Karst. seedlings in nine forest nurseries in Sweden using a combination of traditional culturing and direct sequencing of internal transcribed spacer of fungal ribosomal RNA (ITS rRNA) from the roots. Culturing from 1800 surface-sterilised root segments resulted in 2387 fungal cultures representing 42 different taxa. Direct sequencing from 180 root segments resulted in 119 ITS rRNA sequences representing 25 different taxa. In total, 55 different fungal taxa were detected using both methods. Although direct sequencing was more efficient than culturing in detecting different fungal taxa, both methods provided complementary information about fungal communities in roots since each detected rather different groups of fungi. The most dominant taxa detected by culturing were Trichoderma viride Pers. (19.5%), Phoma mucivora Davey & Currah (19.1%), Phialocephala fortinii Wang & Wilcox (17.4%) and Meliniomyces variabilis Hambl. & Sigler (10.2%), while Thelephora terrestris Ehrh. (26.1%), Unidentified sp. NS126 (25.2%) and Heliotales sp. C20 (10.1%) were most commonly detected by direct sequencing. In conclusion, results showed that forest nurseries in Sweden harbour diverse communities of fungi associated with the roots of healthy-looking P. sylvestris and P. abies seedlings. Although fungal communities were often dominated by saprotrophs and endophytes, several facultative pathogens were also detected indicating that under suitable conditions they may be a potential threat to the plants.     

Influence of different nursery container media on rooting of Scots pine and silver birch seedlings after transplanting

Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth.) seedlings were grown in containers filled with growth media based on medium-textured sphagnum peat, coarse perlite and fine sand. The seedlings were then planted into fine and coarse sandy soils in 2.2 l pots, which were subjected to two water-content treatments (only one for birch). After the seedlings had grown five weeks in a greenhouse, rooting into the surrounding soil and shoot growth were measured. Addition of perlite and sand to peat medium slightly affected rooting; thus suggesting minor effects on seedling establishment. However, nitrogen concentration of the seedlings varied between growth media and correlated positively with rooting into the soil. The particle size and water content of the soil affected considerably rooting of the seedlings. Seedling height at the time of planting did not affect rooting or shoot growth. The fact that the fewest out-grown roots occurred in the dry fine sandy soil, suggests that dry soil together with high strength and resistance to root penetration reduce rooting and water uptake by container seedlings most and may thus cause water and nutrient stresses to seedlings after outplanting.     

苗圃落叶松枯梢病的化学防治

本文介绍了苗圃落叶松枯梢病的发生规律及化学防治方法。     

除草醚与阿特拉津混用除草试验

通过本试验表明：除草醚和阿特拉津混合使用，不但对苗木生长无害，而且还能提高除草效果，降低除草成本２０％，克服了长期使用除草醚造成的弊端。     

除草剂对徐州山地林下主要杂草的防除

通过对徐州市林场侧柏人工纯林林下植被进行抽样调查,选取形成林火地面易燃物的主要杂草一年蓬、野燕麦为研究对象,用农达(草甘膦异丙胺盐41%水剂)、MCPA(2甲4氯钠盐13%水剂)、精禾草克(精喹禾灵5%乳油)3种防除效率较高的除草剂进行试验。结果表明,农达和MCPA不同浓度混合溶液具很好的防除效果。从生态环境、防除效果和经济成本等因素综合考虑,200倍农达稀释液与200倍MPCA稀释液的混合液对一年蓬和野燕麦防除效果最佳,可应用在森林防火隔离带的建设中。     

吉林省林业苗圃土壤养分状况评价

本文通过不同区域点位土壤测试。对吉林省林业苗圃土壤养分状况、酸碱反应进行了评价。根据已掌握的土壤肥力状况。指出科学施肥对改良苗圃土壤。特别是对改良养分含量较低、碱性较强的西部苗圃的土壤具有重要意义。     

苗圃地鸟害生物防控技术研究

对吉林市江密峰苗圃的鸟类、种群数量及有害或有益状况进行调查,并采用驯化雀鹰进行生物防控鸟害技术研究,结果表明:该苗圃有鸟类24种,隶属3目11科,戴胜等10种鸟类主要捕食苗圃地害虫,属于益鸟。在真正啄食种子的14种鸟类中,危害程度存在明显差异,绝大部分危害较轻,严重危害种子的主要是燕雀和家鸽。使用雀鹰驱赶苗圃地中的鸟类,效果十分理想,不仅种子受损率降到经济允许指标以下,而且很少有鸟类受到伤害。     

Field determination of unsaturated hydraulic conductivity of forest soils

This study introduces a field method to determine unsaturated hydraulic conductivity which is applicable to sloping terrain with a limited water supply. A single steel ring infiltrometer and an artificial rainfall simulator are used in this method to reduce the amount of water required to attain a steady-state flux condition. Six tensiometers and a time domain reflectometry (TDR) are employed as the soil capillary pressure head and the volumetric soil water content measurement devices, respectively. Water contents measured by the TDR are corrected using a simple calibration method suggested by Hook and Livingston (1996). Unsaturated hydraulic conductivities are computed based on the instantaneous profile method using capillary pressure head and water content changes measured during a drainage process. The proposed method was applied to a forest soil profile in Rokko Mountain range. Results showed that the relationships between the unsaturated hydraulic conductivity and capillary pressure head developed by the proposed method coincide well with those measured by the conventional steady-state laboratory experiment. The proposedin-situ method is the effective simple means to determine unsaturated hydraulic conductivities of forest soils, since this method is enough accurate and consuming less amount of water and time. This research was partly supported by a Grant-in-Aid for Scientific Research (No. 08760149) from the Ministry of Education, Science, Sports, and Culture, Japan.     

Active organic carbon pool of coniferous and broad-leaved forest soils in the mountainous areas of Beijing

In order to explore the effects of different forest types on active soil carbon pool, the amounts and density of soil organic carbon (SOC) were studied at different soil horizons under typical coniferous and broad-leaved forests in the mountainous area of Beijing. The results showed that the amount of total SOC, readily oxidizable carbon and particulate organic carbon decreased with increasing depths of soil horizons and the amounts at depths of 0–10 cm and 10–20 cm in broad-leaved forest was clearly higher than that in coniferous forests. The trend of a decrease in SOC density with increasing depth of the soil horizon was similar to that of the amount of SOC. However, no regular trend was found for SOC density at different depths between coniferous forest and broad-leaved forests. The ratio of readily oxidizable carbon to total amount of SOC ranged from 0.36–0.45 and the ratio of particulate organic carbon to total amount of SOC from 0.28–0.73; the ratios decreased with increasing depths of soil horizons. Active SOC was significantly correlated with total SOC; the relationship between readily oxidizable carbon and particulate organic carbon was significant. A broad-leaved forest may produce more SOC than a coniferous forest.     

Seedling indices of four tree species in nursery and their correlations with field growth in Tamil Nadu, India

Selection of quality seedlings in nursery is important for raising fast-growing trees for production of fuelwood and other products. In order to identify the morphophysiological variables that can be used in nursery for selection purpose, a study on growth, drymatter production, and rate of photosynthesis was undertaken with seedlings of four tree species, viz, Acacia nilotica, Albizzia lebbeck, Dalbergia sissoo and Eucalyptus camaldulensis. The species varied significantly in growth, drymatter production and photosynthetic rate in nursery. E. camaldulensis was the fastest in growth and A. nilotica had maximum number of leaves. Total drymatter production was maximum in D. sissoo followed by A. lebbeck. The rate of photosynthesis was maximum in D. sissoo followed by A. nilotica and lowest in A. lebbeck. Among the various seedling attributes, height, number of leaves per plant, rootweight and photosynthetic rate exhibited significant correlations with seedling drymatter. Seedling diameter showed weak positive correlations with drymatter of both seedlings as well as two-year old field trees. However, number of leaves per plant, rootweight, shootweight and leafweight showed significant correlations with two-year field tree drymatter, the strongest correlation (r = 0.96, P = 0.001) was found between number of leaves per plant and field tree drymatter. Although plant height and leaf photosynthetic rate showed a positive correlation with two-year field growth, the relationship was statistically non-significant. The study reveals that maximum value for leaf number and dryweight of seedling components such as root, shoot and leaf can be used as criteria for selecting nursery stocks for field planting in semiarid conditions.This revised version was published online in November 2005 with corrections to the Cover Date.     

Biogeochemical cycling in forest soils of the eastern Sierra Nevada Mountains,USA

We review some of the unique features of biogeochemical cycling in forests of the eastern Sierra Nevada Mountains, USA. As is the case for most arid and semi-arid ecosystems, spatial and temporal variability in nutrient contents and fluxes are quite high. “Islands of fertility” are common in these forests, a result of spatial variations in both litterfall and decomposition rates. Dry summer conditions greatly inhibit biological activity in the O horizon, and thus most annual litter decomposition takes place beneath the snowpack when moisture is available. Snowmelt duration is shortened near tree boles because of local warming, resulting in earlier drying of the O horizon, significantly lower decomposition rates, and increased O horizon mass. Water and nutrient fluxes vary spatially because of snowdrift in winter and surface runoff over hydrophobic soils in summer and fall. Moisture variability in the vertical as well as the horizontal dimension has significant consequences for nutrient fluxes. Because of the very dry summers, rooting in the O horizons is absent in these forests, and thus competition between microbes and trees for nutrients in that horizon is non-existent. Nutrients mineralized from the O horizon and not taken up by plants enrich runoff through the O horizons over hydrophobic mineral soils, resulting in very high concentrations of inorganic N and P in runoff waters. Substantial temporal variations in water and nutrient fluxes occur on a seasonal (with snowmelt being the dominant hydrologic event of the year), annual, and decadal basis. The most significant temporal variation is due to periodic fire, which we estimate causes annualized N losses that are two orders of magnitude greater than those associated with leaching and runoff. We hypothesize that fire suppression during the 20th century may have contributed to the deterioration of nearby Lake Tahoe by allowing buildups of N and P in O horizons which could subsequently leach from the terrestrial ecosystem to the Lake in runoff. In general, we conclude that biogeochemical cycling in these forests is characterized by greater spatial and temporal variability than in more mesic forest ecosystems.     

不同功能区林下土壤多环芳烃分布特征及来源分析

以乌鲁木齐工业区、交通区、居民区和公园区的林带作为试验采样区,分别从各功能区林带土壤中多环芳烃(PAHs)的含量、组成、污染情况、来源4个方面,分析了土壤中16种PAHs污染特征。结果表明:乌鲁木齐不同功能区林下土壤平均PAHs的含量为(375.76±32.96)ng·g^-1,其中交通区>工业区>居民区>公园区。低环和高环PAHs含量分别占32.02%和67.98%。工业区林带和交通区林带土壤以4环和3环为主,居民区和公园区以5环为主。工业区和交通区林带土壤以轻度污染为主(42.90%和37.50%);而公园区和居民区以轻度污染(60.00%和66.67%)和未污染(40.00%和33.33%)为主。工业区林带土壤组分中占比最高和最低的分别是茚并(1,2,3-cd)芘(IcdP)占16.01%和?(Chr)占0.98%,交通区林带占比最高和最低的分别是荧蒽(Fla)占16.01%和苊(Ace)占0.49%,居民区林带分别是荧蒽(Fla)占15.66%和?(Chr)占0.21%,公园区林带分别是茚并(1,2,3-cd)芘(IcdP)占19.48%和?(Chr)占0.84%。以煤、木、草等生物质燃烧为污染源的样地最多的是公园区;以汽车尾气、石油燃烧为污染源的样地最多的是交通区。各功能区PAHs的来源主要为煤、生物质等的不完全燃烧。