Influence of soil properties on the growth of sycamore (<Emphasis Type="Italic">Acer pseudoplatanus </Emphasis>L.) in Denmark

Despite high demand on the timber, sycamore (Acer pseudoplatanus L.) covers only about 2% of the forested area in Denmark, mainly because several examples of failed stands have made foresters reluctant to grow sycamore. In order to optimize the use of sycamore, scientifically based knowledge is needed on the specific demands of sycamore to soil properties. Therefore, 34 stands of sycamore covering a broad range of soil types, tree heights and ages were investigated. Tree height and age were determined on 20 trees in each stand and combined into a site index. In each stand, soil water status, slope and ground cover were determined and soil samples were taken and analyzed for pH, organic carbon, total nitrogen, calcium carbonate, bulk density and texture in the laboratory. The data were analyzed by simple regression supplemented by PCA and MLR. Accordingly, sycamore can grow well on a broad range of soils regarding texture and water content. However, soils with stagnant water within 40 cm of the soil surface are unsuited for sycamore. On well-drained soils, increasing clay content caused better sycamore growth, which was also improved on insufficiently drained soils with calcium carbonate. Increased nitrogen content stimulated sycamore growth while, less productive stands occurred on carbon rich soils indicating that carbon and nitrogen contents can serve as sycamore growth indicators. Bulk density, C/N ratio and pH showed no significant influence on growth. The investigation showed that sycamore could grow well on a broader range of soils than hitherto believed.     

郑州市光肩星天牛寄主植物种类及危害现状调查

2009-2010年,对郑州市城市园林绿化常见树种中易受光肩星天牛危害的寄主植物进行全面调查,以了解郑州市光肩星天牛的分布及危害情况.调查发现,郑州市光肩星天牛分布广泛,有较为明显的空间聚集状态;市区西部、北部聚集区域光肩星天牛较东部、南部密集,虫口密度从西向东、由北往南呈递减趋势;聚集密度由大到小依次为:北部＞西部＞...     

Tree and livestock productivity in relation to tree planting configuration in a silvopastoral system in North Wales, UK

Silvopastoral systems in Europe offer the potential of introducing environmental benefits while at the same time increasing the diversity of farm outputs. The establishment of new silvopastoral systems by planting young trees into existing pasture was investigated at a site in North Wales, UK. Two tree species, sycamore (Acer pseudo-platanus L.) and red alder(Alnus rubra Bong.), were planted into pasture at a range of densities and planting arrangements. Growth of trees planted in farm woodland blocks (2500 stems ha^–1) was compared with the growth of trees planted at 400 stems ha^–1 in clumps and dispersed throughout the plot and at 100 stems ha^–1 (dispersed). Over the first six years after planting, alder trees were significantly taller and larger in diameter than sycamore. Sycamore trees planted at close spacing in farm woodland or clumped arrangements were significantly larger in diameter than widely spaced sycamore at 100 and 400 stems ha^–1. Livestock productivity was unaffected by the presence of trees during the six-year establishment phase of the system. The planting of trees in a clumped pattern appears to combine silvicultural benefits to tree growth with agricultural benefits of maintaining livestock production while trees are established.This revised version was published online in November 2005 with corrections to the Cover Date.     

Relationships between elm spanworm, Ennomos subsignaria, juvenile density and defoliation on mature sycamore maple in an urban environment

Using field surveys, we established sampling procedures for estimating defoliation resulting from elm spanworm, Ennomos subsignaria (Hübner) (Lepidoptera: Geometridae), feeding on mature sycamore maple, Acer pseudoplatanus L. (Aceraceae), in St. John's, Newfoundland and Labrador. We also determined whether densities of E. subsignaria eggs, egg masses, early- or late-instar larvae could predict the amount of defoliation at the end of the larval feeding period. Defoliation estimates acquired by sampling branches from only the lower, mid or upper crown explained ≥80% of the variation in tree-level defoliation, suggesting that density–defoliation relationships established using defoliation data from any crown level would also be useful for predicting tree-level defoliation. In linear regressions, egg and egg mass densities explained ≤20% of variation in defoliation and thus only provide a crude relative estimate of the amount of defoliation that will occur. Early- and late-instar larval density in the lower crown explained 53 and 29%, respectively, of the variation in defoliation in the lower crown, where defoliation levels were highest. Thus monitoring early-instar density in the lower crown should provide pest managers with reliable information for decisions regarding whether to apply suppression tactics while allowing enough time to implement these tactics, if necessary.     

园林绿化和工业用材的优良树种--美国梧桐

美国梧桐广泛分布于北美，适应性广，尤其耐水湿。其树形优美，是良好的庭园绿化树种；生长迅速，也是重要的短周期工业用材树种。     

Growth and nutrition of young European ash (<Emphasis Type="Italic">Fraxinus excelsior</Emphasis> L.) and sycamore maple (<Emphasis Type="Italic">Acer pseudoplatanus</Emphasis> L.) on sites with different nutrient and water statuses

This study aimed to improve knowledge about the nutritional status, site requirements and site classification for European ash (Fraxinus excelsior L.) and sycamore maple (Acer pseudoplatanus L.) by reinvestigating young plantations from 1991/1992 on windfall-affected areas in Bavaria/Germany after another decade. Compared to the first survey in 1995, most stands improved their nutritional status until 2006. With the data set of element concentrations in leaves of ash and sycamore available, the range of adequate nutrition could be determined for these species in the pole stage phase. Both species show considerable height growth on a wide range of sites. Mean annual height growth of dominant sycamore trees increased with rising foliar N or P concentrations but not for Ca, Mg, K, Mn, Fe and Al. For ash, there was no relationship between the foliar nutrient level of any element and mean annual height growth. However, total height around age 20 was favourably influenced by high base saturation and a good water supply at well-drained sites. On acid soils, where nutrients are delivered by subsurface water flow, well-growing stands are found as well. Soil water status according to the state forest soil classification had no significant impact on mean annual height growth. Ash and sycamore show reduced productivity on some (moderately) dry soils and fail on poorly drained moist sites. Based on these results, the classification of forest sites suitable for ash and sycamore within the Bavarian study sites was revised. Dedicated to Professor Dr. Karl-Eugen Rehfuess on his 75th birthday.