Termiten aus Kolumbien nach Beobachtungen von German O. Valenzuela und Fritz Schremmer

Zusammenfassung Von den vier besprochenen Termitenarten werdenSyntermes aculeosus Emerson undCornitermes acignathus Silvestri zum ersten Mal aus Kolumbien gemeldet.Comatermes perfectus (Hagen) wird zum ersten Mal als Schädling an Kaffeepflanzen beschrieben, die auf frisch gerodeten Urwaldboden angepflanzt wurden. Der Schaden erstreckt sich auf den Wurzelhals 10–12 cm unter bis 5–7 cm über der Erdoberfläche. Dabei wird die Wurzel zum größten Teil vom Stamm getrennt, der allerdings sekundäre Seitenwurzel bildet.Amitermes foreli Wasmann baut große oberirdische Lehmnester auf der offenen Savanne, die an die Kompaßnester in Australien erinnern. Arbeiter und Soldaten vonS. aculeosus werden von den Indianern gegessen.C. acignathus wurde in einem verrotteten Baumstamm gefunden, scheint aber nicht schädlich zu werden.

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Termites from Colombia observed by German O. Valenzuela and Fritz Schremmer

Comatermes perfectus (Hagen) (Kalotermitidae) is an important pest on living coffee plants in young plantations destroying the root collar.Amitermes foreli Wasmann (Termitidae, Termitinae) build large epigeous mud nests in the open savanna similar to the magnetic or compass nids in northern Australia. The workers and soldiers ofSyntermes aculeosus Emerson (Termitidae, Nasutitermitinae) are eaten by Indians in southern Colombia. This species andCornitermes acignathus Silvestri are the first records from Colombia.

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Mit 4 Abbildungen     

Modelling agroforestry systems of cacao (Theobroma cacao) with laurel (Cordia alliodora) and poro (Erythrina poeppigiana) in Costa Rica

The agroforestry systems of cacao (Theobroma cacao) under laurel (Cordia alliodora) and cacao under poro (Erythrina poeppigiana) were studied at CATIE, Turrialba, Costa Rica. An inventory was taken of the organic matter and nutrients (N, P, K, Ca, and Mg) separating the species into their compartments (leaves, branches, trunks and roots). Studies of the litter and of the mineral soil (0–45 cm) yielded these results: Patterns of nutrient accumulation are discussed in relation to the characteristics of these agroforestry systems.     

An extension of Jacobs' method for measuring residual growth strains in logs

Summary Previous methods for measuring residual longitudinal growth strain distributions in logs are reviewed. An extension is given of Jacobs' method for measuring growth strains which yields residual strain information at many points in the cross section other than along the diametrical plank. Some of the longitudinal growth strain distributions measured using the new method are presented.This work was supported in part by NSF Grant ENG-74-02428     

改制毛竹林害虫虫情变动的探讨

改制前的毛竹林，每两年有一年无笋或少有笋、有几个月林内立竹上无叶，竹子上的害虫种类简单，危害不重，有些害虫少发生或不能发生；能发生或危害重的竹子害虫，在生活过程中，习性多少都发生一些变化，如竹织叶野螟有迁飞习性，毛笋泉蝇、毛竹黑叶蜂部分蛹有滞育习性，赭翅双叉端环野螟有同时以小幼虫和老熟幼虫越冬习性，以适应无笋、少叶的营养环境。改制后的毛竹林地被物挖锄，天敌资源锐减，竹林中年年有笋，立竹上终年披叶，使竹子害虫食物条件改善，竹子害虫种类逐年增加，害虫迁飞、滞育习性的比例逐年减少，危害逐年加重。     

The Quantitative Evaluation of Output Efficiency in Different Cropping Pattems

Quantitative indexes such as land equivalent ratio, yield equivalent and value of output equivalent were used to evaluate output efficiencies of different cropping patterns, i.e., sequential cropping, intercrops and crop rotation. Compared to single cropping, land use efficiencies under sequential cropping, intercrops and crop rotation were raised by 62, 38 and 21%, respectively. The unit area yield under sequential cropping, intercrops and crop rotation were raised by 63, 29 and 16%, respectively. The unit area value was also enhanced under sequential cropping and intercrops, 76 and 35% higher than that under single cropping. The paper provides a useful tool for comparing farm output efficiency and build up a theoretical basis for further research on output efficiency of various cropping patterns in the future.