Effects of mowing to Solidago altissima populations

Solidago altissima L. is a perennial naturalized plant belonging to Compositae and originated in the temperate eastern North America. Its rhizomes run under-ground and its stem stands straight and grows more than 2m. They have strong vegetative reproductive ability and grow densely in various habitats. They are widely distributed and are now subjected for removal. Generally, it is said that mowing is the most effective way of removal because it is safe and cost effective. The purpose of this study is to understand the influence of mowing on their growth. The study was conducted in Higashi-Hiroshima City, western Japan. Three quadrats (1m×1m) were established in open lands near Hiroshima University. One quadrat was established in a homogenous community with no mowing for the last few years. The remaining two were established in a homogenous community, as well, but with mowing. The former plot is called control plot here and the latter two are called mowing plots. Stem was defined as ramet of the above ground in this study. The numbers, the height and the thickness of ramets in control plot and mowing plots were measured in February 1999. The size of shoots and shoots from original mowed stems in one mowing plot were also investigated in October 1999. As the results, the number of ramets was larger, and the height and thickness of ramets were lower in the mowing plots than the control plot. The thickness of shoots was about half of the original stems. The reactions of this species to mowing might be the result of their priority over producing seeds than their growth. Inherently this species do not have any nature to regenerate by shoots. However it seems they indicate this nature as a reaction to mowing

Vegetation of Mominoki Forest Park, Hiroshima Prefecture

The task of nature parks is not only to preserve precious nature but to provide us with the places for outdoor recreation. Recently some problems on over use have been reported in such parks in Japan. Though it is necessary for conservation of nature to investigate actual vegetation and to examine appropriate management plan in the parks, it was hardly done in Japanese nature parks. We surveyed actual vegetation and human activities in Mominoki Forest Park in Hiroshima Prefecture as a case study of such a research. It remains few climax vegetation in this park, because it was established in a former stock farm. The main vegetation was secondary forest after cutting down and secondary grasslands at the time of establishment. In 1994,most secondary forests developed. A climax wetland forest, Alnus japonica forest still remains. In addition, there were no vegetational covers in artificial lawns due to overuse. We proposed new management plans of vegetation by the basis of this study

Distribution of Dandelions in Higashi-Hiroshima City

The distribution of dandelions (Taraxacum spp.) in Higashi-Hiroshima was described and discussed in relation to the urbanization. It is concluded that two introduced dandelions, Taraxacum officinale and T. laevigatum have been extending their habitation, especially in urban areas. It seems that the native dandelion, T. japonicum lives such special regions as gardens and edges of agricultural lands, where are influenced under human management. The natural hybrids between native and introduced dandelions are frequently found in natural gardens associated with T. japonicum

Twenty-one Years Post-fire Succession in a Small Watershed on Etajima Island, Hiroshima Prefecture, Southwestern Japan 【Article】

This study was conducted in a small watershed in Etajima Island, southwestern Japan to ascertainspecies performance 21 years after the fire using the Braun-Blanquet's method. Five plots were laid outin the burnt area for the interpretation of succession taking the edaphic or topographic conditions into consideration. Two fern species, Gleichenia japonicaand Dicrapnopteris dichotoma, that grew from surviving subterranean organs a year after the fire helped much in the recovery of the vegetation. At theonset of succession, soil erosion was controlled and trees invasion prevented due to the rapid growth anddistribution of these ferns. Vegetation growth showed variations as could be gleaned from the length oftime when the shrub, sub tree and tree layers have pervaded the area. In 1996, the tree layer appeared ina NW-valley side slope (Plot 3) with Pinus densifloraenlarging its crown over other broad-leaved trees.Clethra barbinervis, on the other hand, started developing in the sub tree layer in the plot on valley bot-tom at lower slope (Plot 1), middle valley bottom slope (Plot 2), and NE-valley side slope (Plot 4) in1980, 1989, and 1985, respectively. In 1990, Pinus densifloradeveloped in NW-valley side slope (Plot3) and on the ridge plot (Plot 5). Shrub layer developed in all plots two years after the fire except theplot on the ridge (Plot 5) where shrub appeared after four years

名護市大浦川に植栽したヒルギ科マングローブ植物実生の生残率と死亡要因

[論文] Articl