大量消亡 meaning in English

mass extinction

In the area of dl + wl , paddy fields expanded and have become increasingly important ; while in the area of pf + dl + wl , including mpfs and fpfs , there has mainly only been a quantitative change , namely woodlands have withered away with dry lands and paddy fields have rapidly expanded
农地摸式逐步变为水田十旱地十林地型；在原来是水田十星地十林地的地方，包括山区型和坝区型，则主要是量的变化，即旱地和水田面积的迅速扩张以及林地面积的大量消亡。
That favorable water environment benefited , not only by the rather large percentage of forest cover with quite strong capacity of water conservation in mountain areas , but also by the comparatively lower gravity of soil erosion in the loess plateau in the middle and lower yellow river basin while numerous lakes and swamps still existed at that time and maintained a huge water storage
中古华北之所以仍能保持良好的水环境，并非由于彼时降水远比后代丰富，而是因为山区森林植被仍然良好，具有较强的水源涵蓄能力；黄土高原水土流失不甚严重，黄河决溢移徙较少、危害较轻，湖泊沼泽尚未因泥沙淤填而致大量消亡，可以潴积巨量的水源。