A Role of farmstead groves to conserve biodiversity in agro-ecosystem

在农场周围建造小树林，以保护房屋免受恶劣气候和自然灾害的影响，并确保燃料和建筑材料的安全。我们试图运用景观生态学技术，从维持和创造生物多样性的角度，明确小树林的作用机制和功能。调查是在岩手县的伊泽扇进行的。果园分布在75%的农田中，形成了典型的乡村景观。林林结构与柳杉人工林相似，但少数林林具有次生林特征。小林的物种多样性指数高于近山次生林，可观测到200种以上的植物。因此，许多植物（如森林种、边缘种、作物田种、内生木本种或归化种）侵入了具有广阔边缘面积的水田和人类影响的小树林。结果表明，土壤和鸟类中种子的物种组成具有丰富的物种多样性，而鞘翅目群落则较为贫乏和简单。考虑了鞘翅目昆虫群落生存的严峻和简单的环境条件。阶地面积与林场规模有一定的分布关系：江户时代以前开发的下层林场多为小规模林场，二战以后开发的上层林场多为大规模林场。近年来，利用GIS分析，各阶地表面的小树林面积逐渐减少。由于农业用地维护、燃料革命、老龄化和城市化对农村社会的影响，农田周围的环境明显变得严峻。

Farmstead groves are built surrounding the farmsteads to protect a house against the severe climate, and the natural disaster, and to secure fuel and building materials. We tried to make a role clear the mechanism and function of groves from the point of maintenance and creation of biodiversity by using the landscape ecological technique. Investigation was done in the Isawa Fan in Iwate Prefecture.1. Grove was in 75% of the farmsteads, and formed typical rural landscape. Structure of the gorves was similar to that of Cryptomeria japonica plantation but a few groves had the characteristics of secondary forests. The species diversity index of the groves higher than that of the secondary forests near the hills, so that we could observed 200 species and more of plants in groves. By the reason, many plants (for example, forest species, margin sp., crop filed sp., endozoochorous woody species or naturalized species) invaded into the groves that had wide margin area enclosed with paddy fields and human impacts. As for such results, the species compositions of seeds in soils and birds were rich species diversity, but coleopteron communities were poor and simple. It considered to the severe and simple environmental conditions for coleopteron communities.2. There was a distributional relationship between terrace surfaces and grove sizes : the groves of small size were frequently occurred on the lowest surface developed before Edo Period and those of large size were dominant on the upper surface developed after the Second World War. In recent years, the area of groves in all terrace surfaces decreased gradually by using GIS. It became clear that the environment to surround farmstead groves was severe by the influence of agricultural land maintenance, fuel revolution, ageing and urbanization upon rural society.