尾叶桉叶片氮磷钾钙镁硼元素营养诊断指标

采用临界值法对尾叶桉幼林材积生长进行叶片营养诊断,试验结果表明,氮,磷,钾,钙,镁和硼等营养元素的临界浓度分别为15.3g/kg,1.2g/kg,4.2g/kg,16.1g/kg,2.5g/kg和0.019g/kg;最适浓度范围分别为15.3-18.1g/kg,1.2-1.7g/kg,4.2-5.6g/kg,16.1-19.8g/kg,2.5-3.0g/kg和0.019-0.031g/kg,而对树高生长进行营养诊断时,上选结果稍微有些变化,试验还得到各营养元素比值的临界值和最适范围。     

Pito (Erythrina berteroana) and chipilin (Crotalaria longirostrata), (fabaceae) two soporific vegetables of Central America

With more and more Latin Americans emigrating to the United States, their favorite foods are being imported to meet the demand that has arisen here. Two popular vegetables, especially of Guatemala and El Salvador, owe part of their popularity to their sedative effect. If eaten in sufficient quantity, they induce a deep, relaxing sleep. Prominent in these two countries is the tree called pito (Erythrina berteroana) (Fabaceae), the flowers and tender young shoots of which are sold in large quantity, fresh or frozen. The tree is exceedingly common because it is planted widely, both as a living fence and windbreak. Chipilin (Crotalaria longirostrata) of the same family, is valued for its young leaves and shoots, cooked and eaten as “greens” and also combined with beans, chopped meat or scrambled eggs. Chemical analyses show that the foliage is rich in calcium, iron, thiamine, riboflavin, niacin and ascorbic acid. The seeds and roots ofthe plant are undeniably toxic.     

The Cajeput tree—A boon and an affliction

The cajeput tree, native from Australia through Burma, is planted in forestry projects, for reclamation of swamps, and as an ornamental in warm climates; often escapes and invades vast areas of low land. The hard wood is durable underground and under water; checks and warps unless slowly seasoned, but is handsome when finished and prized for cabinetwork. The bark, chemically similar to cork, has many uses. Cajeput oil, obtained from the leaves, is in limited pharmaceutical demand, being more costly than oil of eucalyptus. Formerly acclaimed as an “antiseptic” tree, “subduing malarial vapors,” the cajeput has become in Florida a prime respiratory irritant. Since the pollen is not airborne, the irritant factor is apparently the volatile properly. Florida beekeepers, previously in opposition to the spread of the nectar-rich cajeput because of the unpleasant odor and taste of the honey, now have found it valuable for brood-rearing and salable after standing and blending.     

Spatial ecology and conservation of two sloth species in a cacao landscape in limón,Costa Rica

The spatial ecology of sloths was studied in an agricultural landscape in Limón Province, Costa Rica. Two sloth species, the three-toed sloth (Bradypus variegatus) and the two-toed sloth (Choloepus hoffmanni), actively used and traveled through a cacao agroforest and its contiguous living fence rows and riparian forests. This agroecosystem was embedded in an agricultural landscape dominated by banana and pineapple plantations and pastures with dispersed trees. The two-toed sloth (C. hoffmanni) was found in 101 tree species and used 34 for food; the three-toed sloth (B. variegatus) was found in 71 tree species and used 15 for food. Choice of preferred species differed between the two sloth species. Trees commonly used by sloths for food and/or refuge in the cacao agroforest included Erythrina poeppigiana, Cecropia obtusifolia, Leucaena leucocephala; in the living fence rows, Cordia alliodora, Erythrina poeppigiana, Ocotea sinuata and Trophis racemosa; in the riparian forests, Coussapoa villosa, Cecropia obtusifolia, Hura crepitans, Pterocarpus officinalis and Spondias mombin; and in the pastures with dispersed trees, Cordia alliodora, Coussapoa villosa, Erythrina poeppigiana, Ocotea sinuata and Hura crepitans. This study demonstrates the importance of the cacao agroforest as well as arboreal elements in other land uses in providing resources for sloth conservation in a larger agricultural landscape.     

Native tree regeneration in native tree plantations: understanding the contribution of Araucaria angustifolia to biodiversity conservation in the threatened Atlantic Forest in Argentina

Deforestation is a global process that has strongly affected the Atlantic Forest in South America, which has been recognised as a threatened biodiversity hotspot. An important proportion of deforested areas were converted to forest plantations. Araucaria angustifolia is a native tree to the Atlantic Forest, which has been largely exploited for wood production and is currently cultivated in commercial plantations. An important question is to what extent such native tree plantations can be managed to reduce biodiversity loss in a highly diverse and vulnerable forest region . We evaluated the effect of stand age, stand basal area, as a measure of stand density, and time since last logging on the density and richness of native tree regeneration in planted araucaria stands that were successively logged over 60 years, as well as the differences between successional groups in the response of plant density to stand variables. We also compared native tree species richness in planted araucaria stands to neighbouring native forest. Species richness was 71 in the planted stands (27 ha sampled) and 82 in native forest (18 ha sampled) which approximate the range of variation in species richness found in the native forests of the study area. The total abundance and species richness of native trees increased with stand age and time since last logging, but ecological groups differed in their response to such variables. Early secondary trees increased in abundance with stand age 3–8 times faster than climax or late secondary trees. Thus, the change in species composition is expected to continue for a long term. The difference in species richness between native forest and planted stands might be mainly explained by the difference in plant density. Therefore, species richness in plantations can contribute to local native tree diversity if practices that increase native tree density are implemented.     

次生林下栽植红松及其调控的研究

研究了次生林下栽植红松的生长状况。结果表明其生长优越于原始阔叶红松林和次生林下的红松的天然更新。次生林下栽植红松生长的最适生态条件是无灌,距大立木2m以远及林冠郁闭度0.5—0.6。     

湖南会同林区杉木人工林呼吸量测定

对杉木人工林的CO2排放动态和杉木各木质器官呼吸量进行了测定,结果表明,杉木树干呼吸的季节变化规律为3~7月份随着树木生长和气温的升高,树干呼吸呈上升的趋势,在7月份达年呼吸速率的最大值,CO2为0.376m g/(m3.m in)。8月至12月呈逐渐递减的趋势,在1~3月份树干呼吸基本上维持在一定数值上,并且杉木树干呼吸在杆材生长时期随着年龄的增大而减小;杉木树干呼吸的日变化规律为:一天中杉木树干呼吸基本上是随着温度升高而增大,随着温度降低而减小,中午前后出现午休现象。在杉木树干呼吸日变化曲线中出现两次高峰期,一次是在12:00~16:00时,另一高峰出现在24:00。根据测出的有关参数,用积分方法推导出杉木树干、树枝和树根的年呼吸量CO2分别为9.67t/(hm2.a)、2.21 t/(hm2.a)和2.12t/(hm2.a),结合叶片呼吸速率测定,计算出杉木林年呼吸量CO2为21.523 t/(hm2.a),其中,叶片年呼吸量CO2为7.523t/(hm2.a)。并初步确定杉木树干的维持呼吸占年呼吸的39.7%。     

Decline in local ecological knowledge in the Colombian Andes may constrain silvopastoral tree diversity

Local ecological knowledge (LEK) can play an important role in ecological restoration by guiding landholder decision‐making towards more ecologically oriented land management. Silvopastures are a promising option for restoring ecological function to degraded landscapes because they increase tree cover and diversity, moderating the impacts of cattle production on ecological processes. Some silvopastoralists possess considerable LEK that can shape silvopastoral tree communities, but little is known about the temporal trends of this knowledge base. We followed up on a survey of workers, managers, and owners of silvopastoral farms in the Colombian Andes 6 years later and found that the ability to identify native trees and describe their uses, and interest in tree planting, were significantly lower. Importantly, the likelihood that an individual would plant a species was linked directly to the number of uses they listed for that species. Furthermore, the utility of species became more important for influencing the probability of planting native trees over time, as general interest in planting trees declined. We show that knowledge about the uses of native trees is critical for promoting cultivation of diverse tree species in silvopastoral systems, and that multipurpose trees are most likely to be planted. Moreover, our results suggest that the socio‐economic changes driving declines in ecological knowledge elsewhere, including outmigration and limited transmission of knowledge to younger generations, appear to erode LEK among Colombian silvopastoralists. Preserving LEK is therefore a critical factor for ensuring silvopastoral and other agro‐ecosystems can contribute to efforts to restore ecological integrity to degraded landscapes.     

Homestead tree holdings: Composition,uses and challenges in Checheche Growth Point,South East Lowveld,Zimbabwe

Understanding homestead tree holdings is important for developing local conservation and livelihood strategies. However, relative to urban homesteads, tree holdings in rural African homesteads remain little studied, especially in semi-arid settings. Using ecological and household surveys, this paper examines homestead tree composition, uses and challenges in Checheche, Zimbabwe. In total, 1,594 trees were encountered across 147 homesteads. Nearly, all homesteads (99%) had trees, and most of them were primarily planted for fruits and shade. Fuelwood, traditional medicines, windbreak and homestead decoration were considered as secondary benefits. Overall, tree density was approximately 112 trees/ha, with an average of 11 ± 7.1 trees per homestead. Homestead tree holdings were explained by age and gender of respondent, homestead ownership and importance attached to and knowledge of trees. Challenges to tree planting mentioned include termites, diseases, livestock damage, high temperatures, water shortages and poor quality soils. Overall, this study shows that homestead tree planting is widespread in semi-arid rural settings but constraints to tree planting ought to be addressed to optimise the benefits from trees. Further research is needed to fully understand the socioecological context that explains tree survival, as a basis for developing interventions for enabling homestead tree planting.     

香根草——优良的水土保持植物

结合近５年来的野外定点观测、盆栽试验和室内分析结果以及国内外有关香根草（Ｖｅｔｉｖｅｒｉａｚｉｚａｎｉｏｉｄｅｓ）的研究资料,系统总结了香根草的生物学特性、生态适应性、作用与用途、应用发展历史和推广应用前景,并提出了今后推广香根草工程应采取的主要措施,以期能为在华南山区,尤其在广东,开展水土保持和建立以香根草为纽带的生态农业提供参考     

Uses, management, and economic potential ofDacryodes edulis (Burseraceae) in the Humid Lowlands of Cameroon

Dacryodes edulis is one of the most preferred tree species by farmers in the humid lowlands of Cameroon. The fruit of the species figures prominently in cross-boundary trade between Cameroon, Nigeria and Gabon. Although there exist empirical data on the volume of trade of the fruit at this level, no data are available at the farm level. A field survey was undertaken to identify uses, management, and farmers’ improvement objectives and to quantify, at the farm-level, the economic potential of the species. The results of the survey indicate thatD. edulis is widely planted and found mainly in tree crop fields and in home gardens. The fruit is highly consumed and traded. The farm-level value of fruit production reaches $US161 a year per grower or collector. The dead branches of the species are used as firewood and its bark is used as medicine. Desired improvement objectives include increased fruit size, good tasting fruit, high yield and reduced time to bearing.     

Testing a facilitation model for ecosystem restoration: Does tree planting restore ground layer species in a grassy woodland?

Planning for the restoration of degraded ecosystems has a strong basis in facilitation successional theory, which, as applied in restoration practice, states that planting of structurally dominant tree species will assist the entry of other native species into a restored community. In Australia, tree planting has been widely applied in restoration of grassy woodland ecosystems. Trees have been postulated to reduce the cover and diversity of weed species, thus facilitating recolonization of native woodland species (indirect facilitation). The expected outcomes of this process include reduced species richness and abundance of exotic plant species and increased species richness and abundance/dominance of natives in areas beneath tree canopies, with these trends strengthening with time. To assess whether this was occurring, we carried out a comparative analysis of species assemblages found underneath and outside of planted tree canopies in sites replanted with juvenile canopy tree species 3–5 or 8–10 years previously. We sampled revegetated stands of Cumberland Plain Woodland, an endangered ecological community in Western Sydney, Australia. We found that neither the number nor abundance of native ground layer species beneath canopies increased as a result of trees being planted at sites of both ages. Where seed is limited, we predicted an increase in abundance of existing native species under planted tree canopies. On this point, the results were mixed and showed some natives with an increased abundance while others decreased. Exotic species richness showed the reverse of the expected pattern, being greater under tree canopies. These findings lend no support to the theory of indirect facilitation. We conclude that simple facilitation models may be inadequate to support planning of grassy woodland restoration and that those models incorporating successional time lags and restoration barriers are likely to be more informative about the development of communities initiated by tree planting.     

Review on antibacterial biocomposites of structural laminated veneer lumber

In this review, the characteristics and applications of structural laminated veneer lumber made from planted forest wood is introduced, and its preparation is explained, including various tree species and slab qualities, treatments for multiple effects and reinforced composites. The relevant factors in the bonding technology and pressing processes as well as the mechanical properties, research direction and application prospects of structural laminated veneer lumber made from planted forest wood are discussed.     

Restricted fence method for covariate selection in longitudinal data analysis

Fence method (Jiang and others 2008. Fence methods for mixed model selection. Annals of Statistics 36, 1669-1692) is a recently proposed strategy for model selection. It was motivated by the limitation of the traditional information criteria in selecting parsimonious models in some nonconventional situations, such as mixed model selection. Jiang and others (2009. A simplified adaptive fence procedure, Statistics & Probability Letters 79, 625-629) simplified the adaptive fence method of Jiang and others (2008) to make it more suitable and convenient to use in a wide variety of problems. Still, the current modification encounters computational difficulties when applied to high-dimensional and complex problems. To address this concern, we proposed a restricted fence procedure that combines the idea of the fence with that of the restricted maximum likelihood. Furthermore, we propose to use the wild bootstrap for choosing adaptively the tuning parameter used in the restricted fence. We focus on problems of longitudinal studies and demonstrate the performance of the new procedure and its comparison with other procedures of variable selection, including the information criteria and shrinkage methods, in simulation studies. The method is further illustrated by an example of real-data analysis.     

SHORT COMMUNICATION: Do farmers reduce genetic diversity when they domesticate tropical trees? A case study from Amazonia

Agroforestry ecosystems may be an important resource for conservation and sustainable use of tropical trees, but little is known of the genetic diversity they contain. Inga edulis, a widespread indigenous fruit tree in South America, is used as a model to assess the maintenance of genetic diversity in five planted vs. five natural stands in the Peruvian Amazon. Analysis of five SSR (simple sequence repeat) loci indicated lower allelic variation in planted stands [mean corrected allelic richness 31.3 (planted) and 39.3 (natural), P = 0.009]. Concerns regarding genetic erosion in planted Amazonian tree stands appear valid, although allelic variation on-farm is still relatively high.     

A comparison of species composition and stand structure between planted and natural mangrove forests in Shenzhen Bay,South China

Aims For assisting faster restoration of damaged or severely disturbed coastal ecosystems, selected mangrove species have been planted on previously mangrove-inhabited sites of the tropical and subtropical coasts of southern China. The objective of this study was to understand the stand dynamics of the planted mangroves and their functional traits in comparison with natural mangrove forests under similar site conditions.Methods Species composition, stand density, tree size distribution, and aboveground production were investigated along three transects in a 50-year-old planted mangrove stand and three transects in an adjacent natural mangrove stand in Shenzhen Bay, South China. Measurements were made on tree distribution by species, stand structure, and aboveground biomass (AGB) distribution. Analyses were performed on the spatial patterns of tree size distribution and species association.Important findings We found that the planted and natural mangrove stands did not differ in stand density, average diameter at breast height (DBH), species composition, and AGB. Spatial distribution of AGB and frequency at species level were also similar between the planted and natural stands. However, the traits in stand structure were more variable in the planted stand than in the natural stand, indicating higher spatiotemporal heterogeneity in the development and succession of planted mangroves. Geostatistical analyses show that both DBH and AGB were spatially auto-correlated within a specific range in the direction perpendicular to coastline. More than 60% of the variance in these attributes was due to spatial autocorrelation. The Ripley's K -function analysis shows that the two dominant species, Kandelia obovata and Avicennia marina, clumped in broader scales in the natural stand than in the planted stand and displayed significant interspecific competition across the whole transect. It is suggested that interspecific competition interacts with spatial autocorrelation as the underlying mechanism shaping the mangrove structure. This study demonstrates that at age 50, mangrove plantations can perform similarly in stand structure, spatial arrangement of selected stand characteristics and species associations to the natural mangrove forests.     

珙桐的生物生态学特性和栽培技术

珙桐是一种残遗种,为我国所特有,只零星分布于长江流域一带湿润亚热带山地,被列为国家一级保护植物。由于它的棕红色头状花序下具有两枚大型的白色苞片,形似白鸽,有中国鸽子树之称,早已成为国外著名的园林观赏树种。我国有不少单位开展引种试验研究,还未得到推广。本文概括地报导了它的地理分布、生物生态学特性和栽培技术,希望能使它在园林绿化事业中占据应有的地位。     

Survival and growth responses of eight Everglades tree species along an experimental hydrological gradient on two tree island types

Questions: How are the early survival and growth of seedlings of Everglades tree species planted in an experimental setting on artificial tree islands affected by hydrology and substrate type? What are the implications of these responses for broader tree island restoration efforts? Location: Loxahatchee Impoundment Landscape Assessment (LILA), Boynton Beach, Florida, USA. Methods: An experiment was designed to test hydrological and substrate effects on seedling growth and survivorship. Two islands – a peat and a limestone‐core island representing two major types found in the Everglades – were constructed in four macrocosms. A mixture of eight tree species was planted on each island in March of 2006 and 2007. Survival and height growth of seedlings planted in 2006 were assessed periodically during the next two and a half years. Results: Survival and growth improved with increasing elevation on both tree island substrate types. Seedlings' survival and growth responses along a moisture gradient matched species distributions along natural hydrological gradients in the Everglades. The effect of substrate on seedling performance showed higher survival of most species on the limestone tree islands, and faster growth on their peat‐based counterparts. Conclusions: The present results could have profound implications for restoration of forests on existing landforms and artificial creation of tree islands. Knowledge of species tolerance to flooding and responses to different edaphic conditions present in wetlands is important in selecting suitable species to plant on restored tree islands     

Field boundaries as barriers to movement of hover flies (Diptera: Syrphidae) in cultivated land

Field boundaries play an important role as refuges, food sources and corridors for invertebrates and vertebrates, and increasing farmland fragmentation impacts on these functions. However, hedgerows and other structures can also impede dispersal by flying insects. The current work uses the pollen of Phacelia tanacetifolia in hover fly guts as a marker to assess hover fly movement in farm landscapes. In the United Kingdom and New Zealand, Phacelia pollen was found in the guts of Ephisyrphus balteatus and Metasyrphus corollae (United Kingdom) and Melanostoma fasciatum (New Zealand) at distances up to 200 m from the source, when there were no barriers between the flowers and the traps used to catch the flies. The rate of decline over distance in the proportion of flies containing pollen was similar for the two countries. The extent to which four replicated field boundary types impeded hover fly movement was tested using post-and-wire fences, lines of poplars (Populus spp.) with gaps, dense poplars and controls (no potential barriers). Phacelia was planted on one side of each boundary, and along the centre of the control plots. The relative presence of the pollen in flies on both sides of the barriers showed that both types of poplar boundary restricted the movement of the flies, but the fence had no effect. In a separate experiment, gravid females of M. fasciatum were captured at a greater height on a shade-cloth fence than were non-gravid females and males. The implications of this work include the functioning and persistence of metapopulations and the influence of field boundaries on population recovery of beneficial invertebrates following pesticide-induced mortality. If field boundaries contribute to a temporal asynchrony between pest and natural enemy populations, this needs to be considered along with the well-established roles of boundaries as refugia for, and sources of, beneficial arthropods.     

木麻黄抗逆性研究进展

木麻黄(Casuarina equisetifolia)是热带、亚热带常绿乔木, 天然生长于滨海疏松沙土中, 为多用途速生树种。长期生长在恶劣的沿海气候和环境中使其具有较强的抗盐、抗风、耐瘠薄、抗涝能力。木麻黄已广泛种植于我国东南沿海, 主要用于防风固沙、盐碱地改良和干旱地区绿化等, 在防御沿海自然灾害、改善生态环境方面发挥了巨大作用。杂交和盐碱地露地育苗等技术使木麻黄的抗寒性 也得到了较大提高。本文就近年来木麻黄抗非生物胁迫的研究进行了综述, 旨在为合理开发和利用木麻黄资源提供参考依据。