斑嘴鸭人工孵化技术及雏鸟的生长发育研究

对11枚斑嘴鸭的卵进行人工孵化及育雏试验,结果表明:雏鸟早期生长发育阶段大致可划分为3个时期,第1时期是快速生长期,第2时期是急速生长期,第3时期是缓速生长期;斑嘴鸭的体重、翅长、跗蹠、体长、尾长、嘴长变化与日龄相关显著。     

眷恋如意湖迟迟不肯南迁的斑嘴鸭

正过了小雪节气,先前到达贺兰县如意湖城市湿地公园的红嘴鸥、普通鸬鹚、苍鹭等5种陆生野生鸟儿们,早已陆续踏上了向南迁徙的归程,唯独剩下了、来的最早的26只斑嘴鸭种群,逗留在如意湖景观亲水平台廊桥处两处芦苇丛中。栖息在此的斑嘴鸭,每天上午八点半左右,有两、三只从芦苇荡游出,在冉冉升起太阳的映衬下,水面上留下了游动的细长的波纹轨迹,鸟儿好似是探路,     

爱鸟护鸟 让春天更时尚

正4月26日的宁夏沙湖景区,来自全国各地的观鸟爱好者屏住呼吸,利用长枪短炮观察着远处湖水中的各种鸟类。"每年4月底,我们都会在沙湖周边开展鸟类调查。"宁夏观鸟协会秘书长李志俊介绍,除了苍鹭、斑嘴鸭等鸟类,近年来白尾鹞、玉带海雕等大中型猛禽也不时在沙湖"亮相",说明沙湖水域的生态环境质量正在不断改善,也提高了沙湖在候鸟迁徙领域中的研究价值。     

浅谈密云县清水河湿地保护小区的保护恢复建设与管理

<正>一、清水河湿地保护小区资源概况清水河湿地保护小区位于密云水库上游的北庄镇,全长近15000米,形成水面150万平米,涉及北庄、东庄、朱家湾等7个行政村。主要以河漫滩、溪流湿地和鱼塘为主,是密云水库流域重要的湿地生态系统,具有重要的生态功能效益和保护价值。清水河湿地保护小区现有动植物资源十分丰富,生态效益明显,是候鸟迁飞路线的重要停歇地和中转站。鸟类就达70多种,包括大天鹅、灰鹤、苍鹭、赤麻鸭、斑嘴鸭、灰雁等,白鹳、黑鹳、鸳鸯等。     

酒泉市肃州区发现黑鹳

酒泉市肃州区首次发现黑鹳。2只黑鹳栖息于泉湖镇四坝海子一处鱼塘边的芦苇丛中,与夜鹭、黑翅长脚鹬、斑嘴鸭、普通燕鸥、白骨顶、黑水鸡、小鸊鷉、凤头鸊鷉等混群,受人为因素干扰大。另在酒泉市北大河流域也发现了1只黑鹳。     

与环境共生 与人类同行——新疆的鸟

鸟类与人类同样因地球环境而生，与万物共同组成我们的世界。从这个意义上讲，鸟与人皆为“地球村”的“村民”。 鸟对人类的贡献俯仰可拾—— 野生鸟类是家禽的来源。家鸡是从原鸡驯化来的，家鸭是从绿头鸭、斑嘴鸭以及白眉洋鸭驯化来的，     

洪湖：野性回归

洪湖的荷花叫红莲,是中国三大莲种之一。夏季洪湖荷花盛开,鲜嫩的荷茎是一种非常美味的水生植物,当地百姓喜欢采之为食。这幅画面也反映了湿地丰富的生产力。洪湖的春天是从大块大块的破冰开始的。2005年2月的一个早晨,天际曙色初露,一群早起的斑嘴鸭小心翼翼地在冰面上行走,踉     

永修野生动物驯养繁殖产业带动林农致富

随着野生动物养殖业的发展,江西省永修县各地驯养繁殖野生动物的积极性逐渐提高。办理许可证开展养殖业的农户逐年增加。该县林业部门加强宣传,积极引导,并及时办理野生动物驯养繁殖、经营的相关手续．提供技术咨询和指导。截至目前,全县驯养繁殖和经营单位发展到9家,驯养的鸿雁、灰雁和斑嘴鸭等物种,市场供不应求,远销广东、浙江等省,带动了当地林农增收致富。     

河北塞罕坝地区鸭科鸟类的调查

2018年11月至2021年3月调查了河北塞罕坝地区湿地鸭科鸟类,共记录鸭科6属16种,旅鸟10种,占总种数的62.5%,夏候鸟6种,占总种数的37.5%。古北种11种,占总种数的68.75%,全北种4种,占总种数的25%,古北—东洋种只有1种,占总种数的6.25%;绿头鸭和斑嘴鸭为常见种;国家二级保护鸟类有3种。     

313只野生鸟类放归东洞庭湖

11月15日上午,在东洞庭湖华容县二门闸望君洲滩涂上,当地80余名干部和新时代文明实践志愿者一起小心翼翼地打开保育箱,将一年来华容县林业部门查获和收容的313只野生鸟类放归大自然。当天放飞的野生鸟类有大白鹭、苍鹭、草鹭、斑嘴鸭、山斑鸠、黑水鸡、白骨顶鸡、稚鸡等8个类别。其中大白鹭为国家二级重点保护动物。     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Boron in forest trees and forest ecosystems

This review critically examines the role of boron (B) in forests in view of recent findings on B nutrition and the continuing occurrence of B deficiency. Many perceptions about the role of B in plants and its uptake and mobility have been altered since the last review on B in forest trees in 1990. Now there is evidence for a fundamental role of B in the formation of the pectic structure in primary cell walls in plants, and further roles in membrane function are being explored. In plants, channel-mediated B uptake, active B uptake and B uptake by mycorrhizas have been shown, B transporters have been identified, and B retranslocation has been shown. We explore these findings and their consequences on forest trees and on ecosystems that they dominate. Particular emphasis is placed on B retranslocation and B in mycorrhizal symbiosis, given their importance in trees.     

Survival and Growth of Picea abies Regeneration after Shelterwood Removal with Single- and Double-grip Harvester Systems

Three stands in Sweden were followed for 7 yrs to study the survival and growth of Norway spruce [Picea abies (L.) Karst.] regeneration after shelterwood removal with single- and double-grip harvester systems. The height of all seedlings within circular plots was recorded before and after final cutting. The tallest seedling and one randomly selected seedling on each circular plot were permanently marked and their annual height growth was measured each year during the period 1993-1999. No significant differences between single- and double-grip harvester systems were found with respect to their effects on regeneration density, survival or annual height growth. The annual height growth of the individual seedlings after shelterwood removal was significantly correlated with seedling height before shelterwood removal. Significant differences were found in annual height growth between seedlings with high and low vitality. Logging damage did not affect the annual height growth. Several practical conclusions were drawn. First, the choice of harvester system does not affect seedling height growth or survival after shelterwood removal. Secondly, the removal of a 200 m³ shelterwood with 200 stems ha^-1 does not seem to constitute a serious problem for seedling survival and growth. Finally, estimated vitality and seedling height both seem to be fairly good predictors of postrelease survival and growth.     

Development of Pinus sylvestris Main Stems Following Three Different Precommercial Thinning Methods in a Mixed Stand

Reducing competition by point cleaning may be an attractive alternative to conventional precommercial thinning in forestry. In this study, survival and development of main stems of Scots pine (Pinus sylvestris L.) following point cleaning were examined in a mixed stand of mainly Scots pine and birch (Betula pendula Roth and Betula pubescens Ehrh.) in northern Sweden. Treatments studied were: no precommercial thinning, conventional precommercial thinning, point cleaning of all secondary stems, and point cleaning of only the secondary stems that were higher than the main stem, within a radius of 0.8 m from the main stem, respectively. A randomised complete block design with three replicates was used. Measurements taken 13 growing seasons after these treatments showed that conventional precommercial thinning was the best treatment for retaining Scots pines as main stems. However, conventional precommercial thinning resulted in the poorest timber quality of the remaining Scots pines in terms of stem taper, thickest branch diameter and relative live crown height. In conclusion, point cleaning has to be followed by a complementary cleaning operation if the objective is to retain Scots pines as main stems in such mixed stands.