The pole-cutting practice in the Bamileke country (Western Cameroon)

In the Bamileke country (West Cameroon), farmers use pole-cutting practice for plantation tree and hedge management. Depending on the species, this practice follows certain rules for gathering, conditioning and planting of pole-cuttings. The main function of the living fences determines the length of the cuttings, the space between them, the hedge structure and its latticing with raffia bamboo. Pole-cutting practice enables farmers to set up pigs, goats and sheep enclosures in the crop fields, as well as to demarcate the family lots. Trees stemming from pole-cutting are pollarded to supply the family group with the majority of their wood product requirements. Pole-cutting practice fulfills the needs of several farmers such as rapid delimitation of land, animal enclosures, firewood, construction wood, timber and cutting production. However, this practice needs a fine hedge management. With decreasing sheep and goat herds and the frequent absence of the farmer, techniques of hedge management are changing.

---

Résumé En pays Bamiléké, sur les hauts plateaux de l'ouest du Cameroun, les paysans utilisent la technique des macro-boutures pour la gestion de leur parc arboré. L'utilisation du macrobouturage suit un certain nombre de règles pour la récolte des boutures, leur conditionnement et leur plantation, qui dépendent de l'espèce bouturée. La fonction principale de la haie détermine la longueur et l'espacement des boutures, leur organisation et leur palissage avec du bambou raphia. Cette technique contribue à la construction de haies séparant l'espace cultivé des parcs à bétail d'une part, et marquant les limites de leur concession d'autre part. Elle répond utilement à un certain nombre de besoins: marquage rapide de limites foncières; séparation élevage/agriculture; fourniture de la majeures parties des besoins de la famille en produits forestiers par une taille en tétard. Mais elle réquière une gestion fine des haies. Avec la diminution des troupeaux et l'abscence fréquente du chef de famille, les techniques de gestion du parc arboré évoluent.

     

卧龙自然保护区震后小型陆栖脊椎动物调查

小型陆栖脊椎动物是一类稳定、灵敏、高效的环境指示动物,将它们作为生态环境变化的指针具有诸多的优越性。通过围栏陷阱法对卧龙自然保护区内小型陆栖脊椎动物在原始竹林与人工竹林中的分布情况展开调查,进而对保护区内小型陆栖脊椎动物资源现状进行评估,并科学地评估我区震后的生态环境。本次调查共记录到小型陆栖脊椎动物物种5目7科15种,其中两栖类2目2科2种,爬行类1目1科1种,小型兽类2目4科12种。采集的样品数量达到316只。     

不同高度阻沙栅栏蚀积过程及防沙效益研究

通过对不同高度阻沙栅栏蚀积过程的野外观测,结合同时期区域风况资料,分析了阻沙栅栏前后地表蚀积形态、蚀积量以及蚀积强度的时空变化特征。结果表明,在沙源充足条件下,不同高度阻沙栅栏上风向表现为风沙堆积,下风向风蚀与堆积共存,且程度与栅栏高度有关,栅栏总体蚀积量和蚀积强度的变化趋势与下风向变化趋势相近。其中,60和70cm高度阻沙栅栏风沙堆积量最大,防沙效果最佳,但二者积沙方向存在差别。70cm高度阻沙栅栏上风向积沙较多;60cm高度阻沙栅栏下风向积沙较多。在实际应用中,应依据防护对象合理配置阻沙栅栏并适时加高,避免阻沙栅栏过低或过高,进而影响防沙效果。此外,依据断面形态、蚀积量和蚀积强度的变化,将栅栏前后分为风沙堆积区、风蚀区和蚀积平衡区。     

On-farm research in a silvopastoral project: a case study

The Silvopastoral Project is being implemented by CATIE in the Atlantic humid lowland of Costa Rica, in order to develop alternatives to the current destructive mode of livestock production. The overall approach is briefly described and two superimposed on-farm experiments are discussed in more detail. The main constraints for on-farm research within the project are analysed: the limited previous knowledge of the area and of the local species, the difficulty of achieving a common understanding about research with collaborating farmers, the need for additional staff supervision and the complexity of the statistical analyses. An attempt is made to draw lessons from the ongoing project regarding how to resolve the apparent contradiction between rigorous scientific requirements and questions of immediate value to extension, the compromises to be achieved between different types of evaluation (statistical, risk, etc.) and the potentials and limitations of farmers' participation in research.     

Instant trees: Using giant vegetative stakes in tropical forest restoration

Remnant trees have been widely reported to facilitate tropical forest recovery, however, few restoration strategies can mimic the role such trees play in their absence. This study evaluated the establishment success and growth of planting oversized vegetative ‘stakes’ (>4 m tall) of three species: Ficus pertusa (Moraceae), Bursera simaruba (Burseraceae), and Erythrina poeppigiana (Fabaceae) at three different sites in southern Costa Rica. I found high establishment rates for all species (range 67–100%) with no mortality for Erythrina. This result was coupled with a rapid development of canopy area over 1 yr for Erythrina (7.69 ± 0.86 m²) and Bursera (1.82 ± 0.86 m²), but not Ficus (0.23 ± 0.04 m²). Similar results are reported for height. The study presents an important new addition to the growing body of literature on the use of stakes in tropical restoration, where, oversized stakes may be planted as solitary individuals in restoration sites to mimic the role played by remnant trees in forest recovery.     

Damage by wind-blown sand and its control measures along the Taklimakan Desert Highway in China

Desertification is one of the most serious environmental problems in the world,especially in the arid desert regions.Combating desertification,therefore,is an urgent task on a regional or even global scale.The Taklimakan Desert in China is the second largest mobile desert in the world and has been called the'Dead Sea'due to few organisms can exist in such a harsh environment.The Taklimakan Desert Highway,the longest desert highway(a total length of 446 km)across the mobile desert in the world,was built in the 1990s within the Taklimakan Desert.It has an important strategic significance regarding oil and gas resources exploration and plays a vital role in the socio-economic development of southern Xinjiang,China.However,wind-blow sand seriously damages the smoothness of the desert highway and,in this case,mechanical sand control system(including sand barrier fences and straw checkerboards)was used early in the life of the desert highway to protect the road.Unfortunately,more than 70%of the sand barrier fences and straw checkerboards have lost their functions,and the desert highway has often been buried and frequently blocked since 1999.To solve this problem,a long artificial shelterbelt with the length of 437 km was built along the desert highway since 2000.However,some potential problems still exist for the sustainable development of the desert highway,such as water shortage,strong sandstorms,extreme environmental characteristics and large maintenance costs.The study aims to provide an overview of the damages caused by wind-blown sand and the effects of sand control measures along the Taklimakan Desert Highway.Ultimately,we provide some suggestions for the biological sand control system to ensure the sustainable development of the Taklimakan Desert Highway,such as screening drought-resistant species to reduce the irrigation requirement and ensure the sound development of groundwater,screening halophytes to restore vegetation in the case of soil salinization,and planting cash crops,such as Cistanche,Wolfberry,Apocynum and other cash crops to decrease the high cost of maintenance on highways and shelterbelts.     

不同年限围栏对昭苏退化春秋草地生物量影响的研究

[目的]探明昭苏春秋草场退化草地在不同围栏年限下群落结构的变化情况,为该地区退化草地改良技术提供理论依据.[方法]采用样方法比较研究不同年限围栏封育对退化草地群落结构、草地盖度、生物量演替特征.[结果]在研究样地中,随着围栏时间的延长草地盖度、生物量显著增加,至围栏4a达到最大,而后下降;地上生物量分别是围栏外放牧草地的3.324.41和3.24倍.优良牧草产量和所占比例随着围栏进程的延长不断增加,但丛生小禾草依次降低,高大禾草与生物量变化一致,针茅优势地位不断强化,在围栏6a形成单优势种.[结论]实验反映出围栏封育不是时间越长越好,封育时间过长导致针茅优势度过高,形成针茅的单优势种草地,将抑制其它植物生长发育,进而影响草地生产力的发挥.     

The tree planting and protecting culture of cattle ranchers and small-scale agriculturalists in rural Panama: Opportunities for reforestation and land restoration

To examine the opportunities available for designing diverse tree planting and land restoration initiatives in agricultural landscapes that contain tropical dry forests, the tree planting and protecting practices of cattle ranchers and small-scale agriculturalists were examined in two study sites in rural Panama. Ninety-nine tree species were identified that they utilize, plant, or protect on their land, the majority of which are native to Panama. The farmers had diverse reasons for maintaining trees, including improving the environment, providing food and shade for cattle, and generating a source of wood for construction, furniture, and firewood. Most of the trees mentioned in the study provide multiple uses and values and the majority of farmers wanted to plant additional trees. Some differences in species preferences and motivations for planting and protecting trees were seen between sites, thereby suggesting that land restoration and tree planting projects should be site specific. Our data indicate that there are ample opportunities to increase native tree cover in our study sites and highlight the need to incorporate farmer input into project design, implementation, and evaluation as a necessary and continuous feature throughout projects.     

沙障风荷载作用下嵌固端受力分析

该文应用大涡模拟方法研究不同孔隙度透过性沙障嵌固端受力变化及其周围流场结构特征。结果表明,非透过沙障在相同速度的促发气流下嵌固端受力远高于孔隙沙障,其嵌固端弯矩和剪力最大值分别为40%孔隙率沙障的2倍和1.5倍,为80%孔隙率沙障的16.5倍和14.45倍,沙障嵌固端最大弯矩和剪力值随孔隙率增大而逐渐减小。在持续风力作用下,沙障嵌固端所受弯矩和剪力大大降低,沙障孔隙率为0时,其最大弯矩和剪力值约为其平均值的9.4倍和6.9倍,而沙障孔隙率为80%时,最大弯矩和剪力值分别约为其平均值的2.3倍与2.5倍。沙障孔隙度在一定范围内变化时,其周围流场结构有一定的相似性,以50%孔隙率为分界点可以分为2组,每组沙障嵌固端受力各有其相似的变化特征。研究可为沙障设计插入深度提供理论支撑。     

围栏内外白喉乌头刈割防除探索

[目的]探明不同刈割次数在围栏内外对白喉乌头的防除效果.[方法]设置围栏内外刈割次数实验,采用方差分析比较法(Duncan新复极差法)对围栏内外不同刈割次数样地内白喉乌头的密度、高度、株丛径、有性繁殖丛数进行比较分析.[结果]在不同的生境下采取不同的刈割次数进行防除,当年导致处理问的白喉乌头各监测指标存在显著差异.[结论](1)短时间的围栏封育对白喉乌头的防除效果并不明显.(2)三次刈割可以从根本上解决其有性繁殖带来的蔓延危害.(3)当年的三次刈割即在人为干扰下的长期竞争中使白喉乌头处于劣势,实现防除目的.