三、何謂地景格局(landscape pattern)？請說明我們當前觀察到某一區域的地景格局的現狀是如何受到一些重要力量交互作用影響而形成？(提醒：variability in abiotic conditions such as climate, topography, and soils; biotic interactions; past and present patterns of human settlement and land use; dynamics of natural disturbance and succession)(20分)