Habitat Segregation of the Weeds as an Indicator of the Soil Hardness
スポンサーリンク
概要
- 論文の詳細を見る
1. To analyze the structure of weed communities, the concept of habitat segregation is a most important problem to solve. The phenomenon of habitat segregation of weeds was divided into two groups based on their relationship between the life form and habitat, one is homogeneous habitat segregation and the other heterogeneous habitat segregation. The first is that in which the same species occurs in different life form and a different habitat, and the second is that in which different species occurs in different habitat, and different life form in many cases. 2. Since the spring in 1951, the authors have investigated the habitat segregation of the weeds in cultivated fields and roadways, and special attention was focused on the latter. As for the measurement of soil hardness, the authors used the soil hardness-tester designed by Yamanaka. 3. As the places for the investigations we selected three regions of granitic sandy soil (at Takasu, Hiroshima), so-called Kanto loam (at Oome, Tokyo) and a meadow soil, river bed type (at Tomizu Odawara). 4. In the three regions mentioned above, the authors investigated the weed communities on fields and play-grounds, results are as follows; habitat segregation of the roadside weeds is not influenced by chemical components of their bed soils, but by soil hardness influenced by artificial factors; the treading of men and wheels. 5. Most of habitat segregation, according to the soil hardness, were of the heterogeneous habitat segregation. 6 In the three regions mentioned above, the authors investigated the average cover degree of each species and soil hardness in a large number of quadrats, and from the results the main growing range of weeds due to the soil hardness is classified into following 3 parts, that is, "soft" "hard", and "very hard". "Soft" (index of soil hardness 0-11, absolute hardness 0-1.7cm/kg^3) to which belongs the main growing range of weeds on cultivated land. In the habitat of "very hard" of soil hardness weeds are very much trampled and pressed (index 25-30, absolute hardness 28-115cm/kg^3, and occasionally, to index 32, at stands of more than 30 in index, the growth of weeds is very poor, and usually almost bare). For example, the tracks of wheels and the passage of the pupils on the play-ground belong to "very hard " habitat, and here the following weeds grow; Eleusine indica GAERTN., Juncus tenuis WILLD., Polygonum aviculare L., Eragrostis ferruginea BEAUV., Poa annua L., Plantago asiatica L. In Middle-valued "hard" habitat (index 11-25, absolute hardness 1.7-28cm/kg^3), there grow most of roadside weeds. And some of the weeds on this habitat alter their life forms if they invaded the field of "very hard". 7. Each species of weeds has a different growing range and occurs in a restricted habitat segregation. 8. Moreover, soil moisture has a tendency to have an inverse value to soil hardness. The pH and chemical components of the soil such as P_2O_5 and CaO do not seem to be much of an influencing factor governing habitat segregation.
- 横浜国立大学の論文
- 1954-07-10
著者
関連論文
- Habitat Segregation of the Weeds as an Indicator of the Soil Hardness
- The Mosses of the Ongul Island and Adjoining Coastal Areas ofthe Antarctic Continent