栗茶间作模式下茶树根系的基础特性

对安徽枞阳县周潭镇大山村中国森林生态网络大山试验示范区的栗茶间作茶园和单作茶园茶树根系的特征进行了试验研究。结果表明:栗茶间作促进了茶树根系的生长。间作茶园茶树根系的干重、吸收根比例、比根长和根系生理活性明显大于单作茶树根系;间作茶园茶树根系在土壤中的分布比单作茶树根系更深、更均匀;间作茶园内茶树和栗树根系在土壤空间中各自具有相对不同的生态位。栗茶间作具有较好的生态学基础,是一种可持续发展的茶园经营模式。     

间作对安吉白茶生长与叶绿素荧光动力学特性的影响

探讨薄壳山核桃与茶间作后安吉白茶生长和叶绿素荧光动力学特性差异，为构建薄壳山核桃和安吉白茶高效复合栽培提供理论依据。薄壳山核桃与安吉白茶间作分别以乔木树冠下(T1)、树冠缘(T2)、树冠外(T3)和纯安吉白茶园(T0)等4个测定点，测定10年生安吉白茶茶树新芽数、新稍生长量和单位面积产量等生长指标，结合茶树速生期(7—9月)叶绿素荧光动力学参数指标，分析探讨林茶间作不同光照条件下安吉白茶生长与叶绿素荧光动力学特征。结果表明(1)林茶间作茶树的新芽数、新梢长度等生长指标均显著高于纯茶园，其中乔木冠缘茶树生长指标较优；间作茶园茶树的百芽鲜(干)质量显著高于纯茶园，单位面积茶树新芽鲜质量以冠缘、冠外显著高于冠下和纯茶园，茶树新芽干质量为冠缘处最高，其次为冠外，冠下与纯茶园较低；(2)通过各测定点叶绿素荧光动力学OJIP曲线分析，7—8月高温强光下薄壳山核桃冠缘处茶树的荧光信号强度较强，8月纯茶园茶树的荧光点位显著低于间作茶树，9月各测定点茶树荧光曲线重合度较高。薄壳山核桃冠缘、冠外茶树相对可变荧光差异曲线(ΔV_t)波动较小，冠下茶树荧光的J相在7月快速下降但在9月却陡然...     

不同郁闭度对茶树净光合速率及茶园生态因子的影响

以安徽省金寨县栗茶间作园为研究对象,对不同郁闭度条件下茶树的净光合速率及茶园生态因子进行测定。结果表明:6月,露地茶园(对照)茶树的净光合速率在13∶00时出现"光合午休"现象,而有遮荫的茶园均未出现"光合午休"现象。在遮荫情况下,气温、土壤温度均低于露地茶园,且郁闭度越大温度越低;而空气湿度和土壤湿度均高于对照纯茶园,且郁闭度越大湿度越大。在郁闭度0.3的林下最有利于茶树生长和茶叶品质的提高。     

茶园间种泡桐生态及经济效益的研究

前言茶树原产于我国云贵高原亚热带—热带湿润季风地区。在强光、高温、低湿条件下,茶树生长不良,茶叶品质下降。近二十多年来,世界主要产茶国家先后致力于改变茶园生态环境而提高茶叶品质的研究。我国早在唐代、宋代就有了茶粮间作、茶桐间作的记载。1959年云南普文农场在热带茶园成功地建立了橡胶与茶树间作的胶茶人工群落。1970—1985年唐荣南、王融初分别成功地建立了湿地松与茶树、葡萄与茶树的人工群落。本试验试图选用强阳性、深根落叶阔叶树——泡桐与茶树间作,建立多层次的复合生态系统,改善茶叶品质,促使茶叶稳产高产,同时提供部分优质木材,取得较高的经济效益。     

北方茶林间作对茶树叶片组织结构和产量的影响

在山东泰安部分茶园做了间作板栗和银杏试验,结果表明,茶林间作郁闭度在0.3~0.4之间时,茶树叶片较对照上表皮增厚27%、栅栏组织增厚15.3%、全叶增厚3.1%,有利于抗旱、抗寒;茶林间作郁闭度在0.4~0.6之间海绵组织与栅栏组织的比值大、叶质柔嫩、持嫩性好,夏季茶叶产量可较对照提高89.8%;茶园间作银杏对茶树生长和鲜叶产量较有利。     

板栗、茶树间作观察与分析

板栗、茶树间作观察与分析板栗为喜光深根性高大落叶乔木，枝叶疏展，春季始叶于４月中下旬，秋季落叶始于１０月下旬，是我地采收秋果的主要经济树种之一。茶树为耐阴浅根性常绿灌木，是早春采制碧螺春茶的经济作物。一般而言，两者具有良好的共生条件。两者间作能提高单...     

崂山风景区公路边林茶间作对茶鲜叶铅含量的影响

研究了崂山风景区几条主要旅游公路两侧茶园中间作不同经济林树种对茶鲜叶Pb含量的影响。结果表明,调查区域单一种植的茶园的茶鲜叶均存在不同程度的Pb污染,离公路较近的茶园Pb污染较重,但茶园离公路的距离与茶叶Pb含量之间不存在显著相关关系。不同形式的林茶间作可以降低茶叶鲜采叶的Pb含量,茶园距公路愈近,或间作树种树冠覆盖率愈高,这种影响愈明显。公路边茶园临公路一侧建立林果隔离带也可有效地降低茶叶Pb含量。     

夷陵区茶杉混交型生态茶园建设与探讨

<正>夷陵区委、区政府非常重视茶区生态化建设,并将茶Camellia sinensis O.Ktze.杉Cunning lanceolata(Lamb.)间作、茶栗Castanca mollis-sima Blanco间作等作为退耕还林、农业产业化项目的主要经营模式来抓。近10年来,投入上千万资金扶持茶区生态化建设,目前已成林的混交茶园达0.33万hm2。茶区邓村乡从1990年开始营造     

茶叶与气象

茶叶是一种老少皆宜的饮品,它对气象条件特别敏感,若想达到最佳的饮用效果,必须考虑四季气候。云雾山中出名茶茶树是我国热带、亚热带地区最为普遍的经济树种,最适宜生长在温暖湿润、有遮荫的山区,弱光、遮荫的环境,既能促进茶叶内芳香物质的形成,又能抑制产生茶叶涩味的茶多酚类物质的积累,从而提高茶叶的品质。山区多云雾。这些悬浮在空气中的小水滴能够变太阳的直接辐射为散射辐射,使光量减少,强度削弱,适应了茶树喜弱光、耐荫的特性。高山云雾里,空气相对湿度一般在90%左右,茶树叶面蒸腾少,叶内粗纤维也少,加之降水充沛、土壤墒情好,既有利于茶树梢上的芽叶形成,又能使芽叶柔嫩,色味俱佳。山区的地形和植被,形成了良好的遮荫环境,使茶园里的太阳直接辐射时间减少,从而有利于茶树的生长和茶叶品位的提高。由此可见,自古流传的“云雾山中出名茶”的说法是有科学和事实依据的。您会贮存茶叶吗?茶叶的外形、颜色和内在质量受环境因素制约较大,影响茶叶色、香、味的环境因素主要是湿度、温度、光线三个气象因素。茶叶对湿度的要求非常高,室内空气湿度一般都大于70%,而茶叶里的含水量却不能超过5%;0℃-5℃的环境下,茶叶能较长时间保持原来的色泽和香味。茶叶最适合...     

油茶-茶复合模式对茶树光合特性的影响

为了揭示油茶-茶复合模式的生理生态学理论基础,分析了油茶-茶复合模式和纯茶模式内茶树叶光合特性日变化及季节变化的差异情况,并对茶树光合特性与生态因子进行了多元线性逐步回归分析。结果表明:纯茶模式内茶树净光合速率的日变化曲线为双峰曲线,即午休现象较为明显,而复合模式的为单峰曲线;从整体上看,纯茶模式内茶树叶片的净光合速率高于复合模式;气孔导度的日变化曲线,纯茶呈单峰曲线,而复合模式的呈双峰曲线;胞间CO2浓度的日变化曲线与净光合速率的基本相反,纯茶和复合模式的蒸腾速率表现为先上升后下降的变化趋势。多元线性回归分析结果表明,两种模式下影响净光合速率的主要因子都有气孔导度、胞间CO2浓度、蒸腾速率、空气相对湿度及空气温度,而油茶-茶复合模式的茶树还受到光合有效辐射的影响。     

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.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.