Response of Coniferous Forest Ecosystems on Mineral Soils to Nutrient Additions: A Review of Swedish Experiences

Nitrogen (N) is the only nutrient that promotes forest growth when given individually. An extra stem growth of 15 m 3 ha -1 is obtained during a 10 yr period following an application of 150 kg N ha -1 . Larger growth increases have often been the result of more intensive N fertilization. Lime or wood ash give a minor growth stimulation on sites with a carbon (C) to N ratio below 30 in the humus layer, while the opposite effect prevails on N-poor sites. Nutrients given as soluble fertilizers are readily taken up by trees. Boron deficiency may be induced in northern Sweden after N fertilization or liming. The ground vegetation may be altered by single-shot N fertilization, but long-term effects occur only for intensive regimes. Lime or wood ash may modify the flora if soil pH is significantly altered: the change will be in response to N availability. Fruit-body production of mycorrhizal fungi is disfavoured by chronic N input, but also by lime or ash. However, the mycorrhizal structures on root tips are less affected. Faunistic studies are not common and those present are mostly devoted to soil fauna. A practical N dose of 150 kg N ha -1 has no clear effect, but higher doses may reduce the abundance in some groups. Hardened wood ash does not significantly affect the soil fauna. Lime favours snails and earthworms, while other groups are often disfavoured. The response of aquatic fauna to terrestrial treatments has hardly been studied. N fertilization generally results in insignificant effects on fish and benthic fauna. Lime and wood ash reduce the acidity of the topsoil, but practical doses (2-3 t ha -1 ) are too low to raise the alkalinity of runoff unless outflow areas are treated. N fertilizer use in forestry and N-free fertilizers lack effects on acidification. N fertilization may, however, be strongly acidifying if nitrification is induced and followed by nitrate leaching. N fertilization often results in increased long-term C retention in trees and soil, but does not promote significant N 2 O losses. N may temporarily reduce CH 4 oxidation in soil, but there are indications of a long-term opposite effect. Lime and poorly hardened wood ash may cause losses of C from N-rich soils. Only a few per cent of added N are leached to surface water following practical N fertilization, while N-free fertilizers do not induce N leaching. Soil incubations and soil-water studies suggest an increased risk for nitrate formation and leaching where lime or wood have been added to N-rich soils, but increased leaching to surface water has not been observed. Wood ash causes a temporal increase in bioavailability of cadmium (Cd). Other fertilizers may indirectly increase the availability of heavy metals. Wood ash may contain radioactive caesium 137Cs, but addition of such ash does not increase radioactivity in plants and soil.     

Temporal patterns of seedling mortality by pine weevils (Hylobius abietis) after prescribed burning in northern Sweden

Damage by the large pine weevil, Hylobius abietis (L.), is a major threat to conifer plantations throughout Eurasia, but damage is usually less severe in northern areas. However, pine weevil damage seems to increase if the sites are burnt. The aim of this study was to determine the effects of variations in the time of planting (with respect to the total age of the clear-cut and the time since burning) on pine weevil damage to seedlings on burnt sites in northern Sweden. The study also explored whether there is an optimal time for planting at which damage levels are reduced to acceptable levels. Ten sites were selected in an inland area of northern Sweden where pine weevils are normally scarce. The sites were dry–mesic and represented a range of times since clear-cutting and since burning. The sites were planted in June 1998, 1999 and 2000 with 1-year-old container-grown seedlings of Norway spruce [Picea abies (L.) Karst.]. Pine weevil damage was reduced if planting was done no earlier than 3 years after clear-cutting and no earlier than 2 years after burning. Planting too soon after burning, irrespective of the age of the clear-cut, resulted in unacceptably high damage levels.     

Effect of edge stands on the development of young Pinus sylvestris stands in southern Finland

Abstract

The quantitative effect of pine-dominated edge stands in southern Finland on the density and growth of pine saplings was addressed in the study. The cumulative effect of a mature edge stand on the development of a pine sapling stand with variable cutblock sizes was also estimated. The data were acquired from 10 study sites with a Scots pine sapling stand with a current dominant height of 1–6 m and an adjoining middle-aged to mature edge stand dominated by Scots pine. Tree level models were constructed to describe and simulate the structure and development of the sapling stands. The results indicated that dividing an average regeneration area (2 ha) into smaller cutblock units (1.0–0.5 ha) appreciably increased the edge stand effect. Total stand volume growth was 6% lower on 1 ha cutblocks, and 31% lower on 0.5 ha blocks, than on 2 ha blocks.     

樱类品种观赏性状初步研究

以宁波仗锡樱花基地引种的15个樱类品种为试材,研究其在宁波地区的开花物候期和观赏性状表现。结果表明:在宁波露地栽植条件下,多数品种的始花期集中在3月下旬—4月中旬,各品种单株花期12～21 d不等,总花期维持20～35 d之间。始花期以东京樱最早,虎尾樱最晚,红叶樱、冈目、关山较晚;花期以关山最长,八重红大岛次之,虎尾樱最短。重瓣品种中白菊樱、关山、八重红大岛和普贤象花大、色艳、花型美丽、花量大、植株健壮;单瓣品种中一叶樱、染井吉野和东京樱花量大、开花时间早、生长势好,可推广种植。     

土壤铜形态与环境因素的关系及其对黑麦草生长的影响

采用盆栽试验研究酸度与氮素水平对土壤易溶态铜形态的影响,以及土壤铜含量与形态对黑麦草生长的影响。结果表明,土壤水溶态铜、有机碳结合态铜、离子态铜与铜处理水平呈极显著正相关关系,相关系数分别达到0.70、0.96、0.61。土壤酸度影响土壤中各形态铜的含量,随pH值降低土壤水溶态铜、离子态铜均显著增加,在pH4.7土壤上二者的含量随铜处理浓度的不同分别为pH6.0土壤上的1.6～6.3倍和39～148倍,两种土壤上水溶态铜、离子态铜含量差异达显著水平。铜处理水平、水溶态铜、有机碳结合态铜、离子态铜含量均强烈影响黑麦草的生长和其对铜的吸收,牧草鲜重与各形态铜呈极显著负相关,相关系数分别为-0.73、-0.76、-0.71、-0.72,而植株铜含量则与各形态铜间呈极显著正相关关系,相关系数分别为0.61、0.87、0.56、0.87。土壤氮素水平影响土壤溶解有机碳的含量,但对土壤各种铜的形态及牧草对铜的吸收并无显著影响。     

Excess dietary cholesterol may have an adverse effect on growth performance of early post-larval Litopenaeus vannamei

One experiment was conducted to determine the nutritive value of cholesterol for post-larval shrimp, Litopenaeus vannamei. Four isoenergetic and isonitrogenous diets supplemented with four levels of cholesterol (D1, D2, D3 and D4 with 0, 0.5%, 1% and 2% cholesterol, respectively) were fed to triplicate groups of L. vannamei shrimp (mean initial wet weight 0.8 mg) for 27 days. After the trial, shrimp fed the D1 diet had the best growth performance (final body weights: FBW; weight gain: WG; specific growth rate: SGR), while there was no significant difference between diet treatments with respect to survival. The whole body crude protein level in the shrimp decreased with the increase in dietary cholesterol levels, while the whole body crude lipid level in shrimps in the D4 diet treatment was significantly higher (P < 0.05) than in other diet treatments. Dietary analysis indicated that the D1 diet contained 0.92% cholesterol prior to supplementation, which may have satisfied the dietary cholesterol requirement of post-larval L. vannamei; excess dietary cholesterol may thus lead to adverse effects on the growth performance of post-larval shrimp.     

Uterine biology in pigs and sheep

There is a dialogue between the developing conceptus (embryo-fetus and associated placental membranes) and maternal uterus which must be established during the peri-implantation period for pregnancy recognition signaling, implantation, regulation of gene expression by uterine epithelial and stromal cells, placentation and exchange of nutrients and gases. The uterus provide a microenvironment in which molecules secreted by uterine epithelia or transported into the uterine lumen represent histotroph required for growth and development of the conceptus and receptivity of the uterus to implantation. Pregnancy recognition signaling mechanisms sustain the functional lifespan of the corpora lutea (CL) which produce progesterone, the hormone of pregnancy essential for uterine functions that support implantation and placentation required for a successful outcome of pregnancy. It is within the peri-implantation period that most embryonic deaths occur due to deficiencies attributed to uterine functions or failure of the conceptus to develop appropriately, signal pregnancy recognition and/or undergo implantation and placentation. With proper placentation, the fetal fluids and fetal membranes each have unique functions to ensure hematotrophic and histotrophic nutrition in support of growth and development of the fetus. The endocrine status of the pregnant female and her nutritional status are critical for successful establishment and maintenance of pregnancy. This review addresses the complexity of key mechanisms that are characteristic of successful reproduction in sheep and pigs and gaps in knowledge that must be the subject of research in order to enhance fertility and reproductive health of livestock species.     

饲粮蛋白质水平对育成期母貂生长性能、营养物质消化代谢及血清生化指标的影响

本文旨在探讨饲粮蛋白质水平对育成期母貂生长性能、营养物质消化代谢及血清中与氮代谢相关的生化指标的影响。选择健康（５０±３）日龄断奶的雌性水貂 ６０只,平均体重为（０．５７７±０．０７３）ｋｇ,随机分成 ６组,每组 １０个重复,每个重复 １只,单笼饲养。６组水貂分别饲喂蛋白质水平为 ２８％、３０％、３２％、３４％、３６％、３８％的试验饲粮。在水貂 ６５、８０、９５、１１０日龄时各进行 １次消化代谢试验,分析各日龄水貂的蛋白质消化率、脂肪消化率、氮沉积、蛋白质生物学价值、饲料转化率及体增重等指标。结果表明：５０～６５日龄,３８％蛋白质组体增重极显著高于２８％和 ３２％蛋白质组（Ｐ＜０．０１）,３８％蛋白质组饲料转化率极显著优于 ２８％和 ３２％蛋白质组（Ｐ＜０．０１）;５０～１１０日龄,３２％和 ３４％蛋白质组体增重显著高于 ２８％蛋白质组（Ｐ＜０．０５）。９５日龄时,３２％、３４％和 ３８％蛋白质组的蛋白质消化率极显著高于 ２８％和 ３０％蛋白质组（Ｐ＜０．０１）。１１０日龄时,３４％蛋白质组蛋白质生物学价值和净蛋白质利用率极显著低于其他试验组（Ｐ＜０．０１）。１１０日龄时,３８％蛋白质组尿素氮含量极显著高于其他各组（Ｐ＜０．０１）;３４％和３６％蛋白质组总氨基酸含量显著高于 ２８％蛋白质组（Ｐ＜０．０５）。综合试验中的测定指标,建议５０～６５日龄,水貂饲粮蛋白质水平为 ３６％ ～３８％;６６～８０日龄,水貂饲粮蛋白质水平为 ３４％ ～３６％;８１～１１０日龄,水貂饲粮蛋白质水平为 ３２％ ～３４％。     

Below‐Canopy distribution of photosynthetically active radiation and its relation to seedling growth in a boreal Pinus sylvestris stand

A simulation model was used to predict the spatial distribution of direct and diffuse photosynthetically active radiation below a heterogenous canopy of a Pinus sylvestris stand in eastern Finland. Seedling growth was related to both measured and predicted radiation. The model predicted rather well the overall pattern of radiation distribution beneath the canopy. All the growth parameters of Pinus sylvestris seedlings (height, current height increment and mean height increment) correlated positively with the amount of both measured and predicted radiation. The correlation between seedling growth and irradiance was better for predicted diffuse radiation than for total radiation. This was probably because diffuse radiation, being symmetrically distributed around trees, correlates more strongly than direct radiation with other factors affecting seedling growth.     

不同窝箱环境对育成期水貂生长性能的影响

选择45日龄健康公母水貂各50只,随机分为5组,每组10个重复,其中A、AB、AC、AD组均为新型窝箱且构造各不相同,E组为传统窝箱。结果表明:窝箱环境对母貂的体重没有显著影响(P>0.05);AD组公貂的体重明显低于其他各组,与E组差异显著(P<0.05);不同组别水貂采食量所呈现的差异性基本上与水貂体重所呈现的差异性大体一致;窝箱环境对水貂干物质和蛋白质消化率没有显著性作用(P>0.05);不同组间母貂的氮代谢水平基本一致(P>0.05),E组公貂食入氮和粪氮最高,但在氮沉积和净蛋白利用率上与其他各组不存在显著性差异(P>0.05);AC窝箱干净度最高,各组间不存在显著性差异(P>0.05)。由此得出:窝箱环境不能影响饲粮营养物质的消化代谢能力,但能影响公貂的采食量及体重。