There are many negative effects on the prairies and these are; over grazing (ranching), where the animals such as buffalo are kept in a certain area to feed on the grass and its roots to an extent that there is nothing left for re-growing to occur so the soil cannot bind together and the wind blows huge amounts of dry soil away. From the times of the Native Americans there were 60 million bison and buffalo which were ranched but both the Native Americans and Europeans have made these animals almost extinct. This means that the biodiversity of the natural species has changed due to the effects of the humans. The main change of the area has been to do with cultivation. Deforestation and removal of natural vegetation has cleared the land but left no protection for the soil as there is no cover from rainfall and there are no deep roots to bind the soil and bring moisture into the soils, this strains the aquifers as they are now depended on to bring moisture. With large numbers of European settlers coming over from as early as the 16th century they have over cultivated an area they have very little knowledge about. The methods of ploughing and the gradual introduction of large machinery makes the soils vulnerable to erosion as intense mono cultivation has been introduced putting a huge demand on the soil as the large machines kill vegetation and compact the soils and when the land is ploughed in autumn the moisture in the soil is exposed and evapotranspiration occurs and the soil becomes dry and the wind simply blows it away, this causes the ‘dust bowl’ where over time the amount of eroded soil blown away increases to an extent that huge amounts of top soil form dust storms which cover large areas cause huge problems for people, they are very similar to sand storms and can damage and destroy crops, animals and property. The Europeans also burnt a lot of the land in mosaics but as these people had little knowledge about the land they burnt far too much at once and have left the land unable to recharge/re-grow. Eutrophication is where large amounts of fertilisers are put into the soil to boost growth of plants and fertility of the soil, this can change the soil dramatically as when the soil is fertile there will be extensive cultivation on it and when the crop is grown and harvested the soil will be left and not be fertile, there will be no method of managing the soil so the soil is left to erode, also with large amounts of irrigation; salinisation is going to occur which draws salts up through the soil via capillary actions and once the soil is dry, salt pans appear and the soil is infertile. Tourism and rapidly growing populations have a huge effect as they trample the land and use it for urbanisation, this destroys the land which can never return to its normal state so the land is changed forever, 90% of the natural temperate grasslands have been lost, and now the grasslands are fragmented due to the above factors.
Positive effects that will help manage the grasslands are; the replanting of trees (afforestation) and vegetation (fallow land), these all act as wind breaks and crop cover to reduce the amount of top soil eroded and blown away, this can happen with the aid of eutrophication where nutrients such as nitrates are put back into the soil and along with good irrigation allow plants and trees to grow fast. An example is the leguminous pea plant which is nitrogen fixing and provides crop cover and helps bind the soil together to reduce erosion. When these crop cover plants die they will be easily retained by the soil and the nutrients returned straight into the soil to keep it fertile. Contour ploughing aided with zero tillage helps reduce erosion and also minimises loss in fertility of the soils and the area size is controlled. Contour ploughing with strip cropping also helps reduce the area used and also allows the area to be managed carefully and when harvest comes if only the ears of the crop are collected it leaves the stem for crop cover to protect the land from erosion.
The government of both America and Canada have had huge input as schemes have been introduced to help maintain the land and prevent further loss, national parks have been set up in Kansas where the grasslands are carefully managed and maintained, the prairie farm rehabilitation administration (PFRA) has also been set up as a group that will monitor the grasslands and ensure their future. This group also educates farmers with new methods of farming to help farmers with cultivation but also ways in which they can protect the soil, to reduce the dust bowl. Finally farmer diversification can help the grasslands as if there is no farming occurring, the amount of soil erosion will be greatly reduced or just changing the methods of farming will change the state of the prairies. These methods an schemes will cost the government but they will have to invest as the state of the grasslands is always changing and could be lost forever changing the whole ecosystem.