Fruit production ofAcacia tortilis andA. nilotica in semi-arid Ethiopia

Dry, dehiscent fruits ofAcacia tortilis provide important fodder for pastoral livestock in dry seasons on the central Borana Plateau, fruits ofA. nilotica may also be useful during drought. Information was needed on fruit yield to assess what these species could contribute to improved calf feeding systems based on local resources. Fruit production of 10 mature trees per species was measured at five sites for seven months during 1988–9 (n=50 per species). Fruit yields varied according to site, season and species x site (each atP<0.001), but there was no main effect of species (P=0.13). Yields were not correlated with trunk diameter at breast height (DBH) or canopy area within or across species (P>0.05 in all cases). Yields ranged from 0 to 40 kg DM per tree overall, with an average of 5.3 kg DM per tree (or 65 g DM/m² of canopy area). This average tree had a DBH of 26 cm and a canopy area of 81 m². Low and highly variable fruit yields appear to constrain enhanced use of these species here. These species warrant further attention in research and development, however, given their strategic value as forage resources in pastoral systems and their ability to persist in variable environments.     

Relationships between diameter and height of trees in natural tropical forest in Tanzania

The relationship between tree height (h) and tree diameter at breast height (dbh) is an important element describing forest stands. In addition, h often is a required variable in volume and biomass models. Measurements of h are, however, more time consuming compared to those of dbh, and visual obstructions, rounded crown forms, leaning trees and terrain slopes represent additional error sources for h measurements. The aim of this study was therefore to develop h–dbh relationship models for natural tropical forest in Tanzania. Both general forest type specific models and models for tree species groups were developed. A comprehensive data set with 2 623 trees from 410 different tree species collected from a total of 1 191 plots and 38 sites covering the four main forest types of miombo woodland, acacia savanna, montane forest and lowland forests was applied. Tree species groups were constructed by using a k-means clustering procedure based on the h–dbh allometry, and a number of different non-linear model forms were tested. When considering the complexity of natural tropical forests in general and in particular variations of h–dbh relationships due to high species diversity in such forests, the model fit and performance were considered to be appropriate. Results also indicate that tree species group models perform better than forest type models. Despite the fact that the residual errors level associated with the models were relatively high, the models are still considered to be applicable for large parts of Tanzanian forests with an appropriate level of reliability.     

Use of native browse by Fulani cattle in central Nigeria

Shrubs and trees browsed by Fulani pastoralists' cattle in two areas of central Nigeria were identified by means of interviews with the pastoralists and observations of browsing cattle. Thirty-nine plant species were identified, many of them indigenous economic trees. The species were ranked by pastoralists according to importance in cattle diet. Chemical analyses of plant parts eaten and investigation of frequency of occurrence of the species in the study areas revealed that the pastoralists' ranking reflected not only the plants' relative abundance but also their nutritive value.

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Zusammenfassung In zwei Untersuchungsgebieten in Zentral-Nigeria wurden Bäume und Büsche, die von Rindern der Fulbe-Pastoralisten gefressen werden, durch Interviews mit den Rinderhaltern und durch Beobachten von weidenden Rindern identifiziert. Neununddreißig Arten wurden so identifiziert, viele davon einheimische Bäume von zusätzlicher wirtschaftlicher Bedeutung. Die Arten wurden von den Rinderhaltern nach ihrer Bedeutung für die Rinderernährung in einer Rangfolge eingeordnet. Chemische Analysen und eine Studie über Häufigkeit der verschiedenen Arten in den Untersuchungsgebieten zeigten, daß die Rinderhalter nicht nur die Häufigkeit, sondern auch den Nährwert der Pflanzen bei der Rangfolge berücksichtigten.

     

丽水乡土木本观赏植物资源调查及利用

丽水乡土木本观赏植物资源调查结果表明,已开发应用的乡土木本观赏植物有68科129种,对未开发应用的观赏价值较高的21科30种植物,从生物学、生态学及观赏植物学等方面进行系统研究。     

Carbon stock potentials of woodlands in north western lowlands of Ethiopia

ABSTRACT

This paper examined the potential of dry north western woodlands of Ethiopia (Adi Goshu, Lemlem Terara, and Gemed) for carbon stocks. Allometry equations were used to determine the aboveground, belowground, and dead woods biomasses; litter and herbaceous biomasses were determined using direct harvesting method. The result showed the estimated mean carbon stocks of the aboveground, belowground, and the dead wood biomass for the Untapped Boswellia Papyrifera Woodland (UW) in Lemlem Terara site were significantly higher (P < 0.05) than that of the Adi Goshu site. In the Gemed site, the mean Herb Biomass Carbon (HBC) stock was 1.2 Mg ha^?1, which is significantly highest (P < 0.05) than the other two study sites (Lemlem Terara, 0.42 Mg ha^?1 and Adi Goshu, 0.45 Mg ha^?1) for the Tapped Boswellia Papyrifera Woodland (TW). In UW, the mean soil carbon stock of the Lemlem Terara site (58.19 Mg ha^?1) was significantly (P < 0.05) higher than that of Adi Goshu (33.61 Mg ha^?1). In the case of the total carbon stocks in UW stratum, for the Adi Goshu site, the carbon stock was estimated to be about 55.26 Mg ha^?1 while 96.74 Mg ha^?1 for Lemlem Terara. Therefore, Carbon stock in different carbon pools (aboveground and belowground biomass, dead wood, litter, herbaceous biomass, and soil) has a potential to decrease the rate of enrichment of atmospheric concentration of carbon dioxide.     

通化县林地保护与利用规划的编制与探讨

针对通化县林地保护与利用存在的问题,将林地按照商品林、经济林、水源涵养林和保护区划分为4个功能区,根据每个功能区的经营目标不同,实行分区经营、分级保护,为林地的科学保护与利用提供了依据。     

牡丹江南部地区榛子栽培经营技术

围绕牡丹江南部地区榛子资源的栽培与经营技术等问题,对建园的立地选择、栽植方式、栽植管理、病虫害防治等方面进行了介绍。     

Arbuscular mycorrhizal associations in Boswellia papyrifera (frankincense-tree) dominated dry deciduous woodlands of Northern Ethiopia

This study assessed the arbuscular mycorrhizal (AM) status of Boswellia papyrifera (frankincense-tree) dominated dry deciduous woodlands in relation to season, management and soil depth in Ethiopia. We studied 43 woody species in 52 plots in three areas. All woody species were colonized by AM fungi, with average root colonization being relatively low (16.6% – ranging from 0% to 95%). Mean spore abundance ranged from 8 to 69 spores 100 g⁻¹ of dry soil. Glomus was the dominant genus in all study sites. Season had a strong effect on root colonization and spore abundance. While spore abundance was higher (P < 0.001) in the dry season in all three study sites, root colonization showed a more variable response. Root colonization was reduced in the dry season in the site that was least subject to stress, but increased in the dry season in the harshest sites. Management in the form of exclosures (that exclude grazing) had a positive effect on spore abundance in one of the two sites considered. Spore abundance did not significantly differ (P = 0.17) between the two soil depths. Our results show that in this arid region all trees are mycorrhizal. This has profound consequences for rehabilitation efforts of such dry deciduous woodlands: underground processes are vital for understanding species adaptation to pulsed resource availability and deserve increasing attention.     

深圳市植物物种指数与本地植物指数分析

以文献调研为主,结合野外踏查,对深圳市野生植物和常见栽培植物、建成区内本地植物和外来植物进行了统计分析,得出深圳市"植物物种指数"为0.789,"本地植物指数"为0.701;还分析了深圳植物的区系特点和外来植物的应用现状。       

Exotic plant species in the southern boreal forest of Saskatchewan

Exotic species possess abilities to harm the ecosystems they invade. This study assesses the density, frequency and cover of exotic plants in roadside right-of-ways, logged areas and wildfire sites within mixedwood sections of the southern boreal forest of Saskatchewan. A total of 23 exotic species were observed including nine species of Gramineae, seven species of Leguminosae and five species of Compositae. Average density of exotic species in areas recently disturbed by timber harvesting or wildfire was 0.2 stems m⁻² with a frequency of 72%. Exotic species adapted for wind dispersal were best represented including common dandelion (Taraxacum officinale), perennial sow thistle (Sonchus arvensis) and annual hawksbeard (Crepis tectorum). Only two exotic species, T. officinale and Canada bluegrass (Poa compressa), were observed in mature forest; both occurred with a frequency of 13% and an average density of 0.002 stems m⁻². A total of 22 exotic species was found in the right-of-ways quadrats with an average density of 117 stems m⁻² and a frequency of 94%. The most frequently observed exotic species in the roadside right-of-way areas were T. officinale, alsike clover (Trifolium hybridum), S. arvensis, creeping red fescue (Festuca rubra) and smooth brome grass (Bromus inermis). These species are either common agricultural weeds or were part of the original seed mixture used to establish a plant cover in the roadside right-of-ways.     

论集体林区林地产权制度变迁的路径

林地产权制度改革是实现林业可持续发展的需要。文中在分析集体林区林地产权制度缺陷的基础上,提出了林地产权制度变迁的路径。     

Plant community and ecological analysis of woodland vegetation in Metema Area, Amhara National Regional State, Northwestern Ethiopia

We studied woodland vegetation in broad-leaved deciduous woodlands of Metema in northwestern Amhara regional state,Ethiopia to determine plant community types and species distribution patterns and their relationships with environmental variables,including altitude,pH,cation exchange capacity,electrical conductivity(EC),and moisture.We used a selective approach with a systematic sampling design.A total of 74 quadrats,each 25m × 25m at intervals of 150 200 m were sampled along the established transect lines.For herbaceous vegetation and soil data collection,five subquadrats each 1m × 1m were established at the four corners and the center of each quadrat.Three community types were identified using TWINSPAN analysis.All three community types showed high diversity(Shannon-Weiner index),the highest in community type II at 3.55.The highest similarity coefficient was 0.49(49%) between community types II and III,reflecting 0.51(51%) dissimilarity in their species richness.The canonical correspondence ordination diagram revealed that the distribution pattern of community type I was explained by moisture while that of community types III and II was explained by EC and altitude and moisture,respectively.Altitude was the most statistically significant environmental variable,followed by moisture and EC in determining the total variation in species composition and distribution patterns while pH and cation exchange capacity were non significant.In conclusion,we recommend that any intervention should take into account these three discrete community types and their environmental settings to make the intervention more successful.     

植物防御与昆虫反防御的规律及其机制研究进展

从植物防御、昆虫反防御以及环境条件对植物与昆虫之间关系的影响三个方面综述了昆虫与植物协同进化的表现和作用机制,并对该领域的未来发展进行了展望。     

南方集体林区林地产权制度历史变迁思考

阐述了我国南方集体林区林地产权历史变迁的概况及其存在的问题,并对极具中国特色的家庭联产承包制度进行了重点分析,同时指出了20世纪90年代以来兴起的股份合作制作为一种较为有效的制度创新,依然存在的缺陷。最后给出了深化改革的思路。     

Potential of indigenous multistrata agroforests for maintaining native floristic diversity in the south-eastern Rift Valley escarpment, Ethiopia

Most studies undertaken in the field of agroforestry have focussed on system design, soil fertility management, and system interactions. Less emphasis has been placed on biodiversity aspects. The aim of this study is to investigate the potential of indigenous, multistrata agroforests for maintaining native woody species diversity in the south-eastern Rift Valley escarpment, Ethiopia. A total of 60 farms, representing three agroforest types (enset-AF, enset-coffee-AF and fruit-coffee-AF), were randomly selected along altitudinal gradients. Enset (Ensete ventricosum) is a perennial, herbaceous monocarpic banana-like plant which serves as a food plant in Ethiopia. The three agroforests are results of the domestication of natural forests and intensification of the landuse systems centuries ago. Sample-based assessment protocols were employed to place sample quadrats and to measure all individuals in the quadrats. A total of 58 woody species, belonging to 49 genera and 30 families, was recorded. Of all woody species identified, 86% were native. The highest proportion of native woody species was recorded in enset-AF (92%), followed by enset-coffee-AF (89%) and fruit-coffee-AF (82%). Among native tree species, Millettia ferruginea and Cordia africana were the most widespread. In all, 22 native woody species were recorded as of interest for conservation, acccording to IUCN Red lists and local criteria. Among them, Pygeum africanum and Rhus glutinosa were categorised as vulnerable in the wild, and in need of conservation priority. The introduction of non-native fruit trees in agroforests can be a threat to maintenance of native woody species. Management strategies favoring enset and coffee will also put other native tree species at risk. A smaller number of native woody species was recorded in fruit-coffee-AF, but a higher mean basal area and stem number. The mean basal area and stem number ranged from 5.4?±?0.5 to 11.7?±?1.0?m^2?ha^?1 and 625?±?84 to 1,505?±?142 stems?ha^?1, respectively. Altitude explained 68 and 71% of the variation in species richness and abundance, respectively. Finally, it is concluded that recognition of the indigenous agroforestry system as an option for maintaining native woody species should be given more attention, to counteract the local threat of these species from the wild.     

黑龙江省野生浆果植物资源的开发利用

介绍了黑龙江省野生浆果资源的概况和特点 ,提出开发利用的原则与对策。     

病原菌毒素对植物的致病作用

病原菌在侵染植物的过程中产生的毒素一向被认为是致病的重要因子，然而对毒素致病作用的确定却是一个复杂的问题，毒素在一般生物测定中表现出来的对植物组织的伤害与破坏作用并不一定代表其具备致病力的密切相关，但是对于具体毒素在相应病种中的作用程度及对致病力的贡献大小还需要一些更严格的试验予以确定。     

Nutritive value of botanical fractions of Moringa oleifera and Moringa stenopetala grown in the mid-Rift Valley of southern Ethiopia

Nutritive value of botanical fractions (leaves, twigs, pods and whole forage) of Moringa oleifera and Moringa stenopetala were evaluated based on chemical composition, in sacco dry matter (DM) degradability, in vitro gas production and in vitro organic matter digestibility. The objective was to characterize the nutritive value of the different morphological fractions in order to determine their potential as alternative sources of livestock feed. The crude protein content (g/kg DM) was highest (P < 0.05) in M. oleifera leaves (361.2) followed by M. stenopetala leaves (334.4) and lowest in M. oleifera twigs (79.1) and M. stenopetala pods (89.2). The fiber (NDF, ADF and ADL) contents were higher (P < 0.05) in the twigs and pods than the leaves and whole forage in both species. The different morphological fractions of both species had high mineral content, although the Na content was low or marginal in most fractions except whole forage and green pods of M. stenopetala. The in sacco DM degradability ranked the morphological fractions in the order of leaves > whole forage = pods > twigs after 24 h of incubation time. The potential degradability (A + B) was highest (P < 0.05) in M. oleifera twigs (97.9 %) and M. stenopetala leaves (98.5 %) and lowest in the pods of both species (64.4–69.5 %) with intermediate values in all other fractions. No significant differences were observed in the instantly fermentable fraction (a) and rate of gas production (c), whereas lower (P > 0.05) insoluble but slowly fermentable (b) and potential gas production (a + b) were recorded in the pods than in the other morphological fractions of both species. The study showed that the different morphological fractions of the two Moringa species are good source of nutrients with high degradability which could be used as potential supplements to low quality tropical roughages.     

吉林大学前卫南校区园林植物种类结构的研究

吉林大学前卫南校区共有木本植物16科28属51种，其中乔木树35种7879株，针叶树8种1556株，占19．7％；阔叶树27种6323株，占80．3％；花灌木16种16332株；各种绿篱长11425m，绿篱总面积为16370m^2；草坪面积为200000m^2；花卉总面积为11184m^2，其中1a生草花面积为8202m^2，宿根花卉面积为2982m^2。吉林大学前卫南校区园林植物种类结构还不十分合理，今后应进一步调整。     

麻阳西晃山野生观赏植物资源与利用

湖南省麻阳县西晃山有着丰富的野生观赏植物资源。在初步调查的基础上,对西晃山野生观赏植物的观赏类型、科属组成及多样性等进行了初步分析,发现西晃山有422种野生植物具有观赏价值,其中有不少的珍稀种类及观赏价值极高的植物种类。同时对野生观赏植物资源的开发利用提出了建议。