然而19世纪一连串的变化将他们本就困窘的境地变得更加糟糕：森林急剧退化使他们无法捕猎，很多人经营的盐业生意因为盐税而受影响。

Yet their plight was made worse by a series of 19th-century changes, including rapid deforestation, which stopped them from hunting, and the imposition of a tax on salt, which many had traded.

youdao

由于自然和人为因素的共同作用，黑土的质量发生了严重的退化，数量也急剧减少。

Because of complicated function of natural and artificial factors, the quality and quantity of black soil decreased and degenerated heavily.

youdao