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.
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.
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.
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