Thursday, February 13, 2014

Land Use Changes in Central Tibet from 1830-1990. Yak n' barley

Historical documents related to taxes reveal important data on human-environment relationships of the past. The research in this study employed documents from an historical source known in English as the Iron Tiger land decree. The document is titled so after the after the corresponding year in the Tibetan calendar. The researcher sought to compare land use patterns in Tibet from 1830 and 1990. 1990 was a good benchmark since Chinese data collected from earlier in the twentieth century was characterized by unreasonably high estimates surrounding production values.

The land unit in the study is not measured in acres or hectares but rather the kang. The kang refers to the weight of barley required to cultivate a certain area of land, so calculations must be made in order to envision the corresponding area size per kang. The researcher points out that there simply isn’t enough data to look at individual estates and compare them to historical accounts. The study touches briefly on the types of crops and animals found both currently and historically in this region in Tibet which include the following: barley, rapeseed oil for cooking, turnips, potatoes, radishes, yak, dzo (yak-cattle hybrid), sheep, goats, and cattle. Agrarian resources have had huge implications for population growth in the early settlement of Tibet. In addition, the governmental/religious hierarchy of the country are evident in land use changes with monasteries owning huge proportions of the land in certain areas. Because land cultivation in Tibet is largely restricted to low-lying valleys, the researcher used a high resolution digital elevation model (DEM) for charting the territories involves.

Almost all areas experienced increased amounts of cultivated land from 1830-1990. Overall, the primary purpose of this study was to establish a methodology for future studies of land use change in Tibet, so the conclusions largely focus on the establishment that the historical developments in the state of Tibet are intermeshed with changes in land use. So, the implications of the study aren't huge but rather allow for closer looks at the driving forces behind these changes. 

This above figure defines the area of study. 

The above figure denotes the proportions of land ownership amongst various groups as told by the 1830 land decree.
The above figure shows the percent changes in land use from the two benchmarks in the study. 
The above table shows the specific percentages of change for each area in the study. 

Ryavec, Karl. "Land Use/cover Change in Central Tibet, C. 1830-1990: Devising a GIS Methodology to Study a Historical Tibetan Land Decree." The Geographical Journal 167.4 (2001): 342-57.


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  2. I think this presents an interesting way to look at history through the lens of land use change. Seeing how land units can change from kang and the amount of land allocated to certain groups reveals not only the society's relationship and attitude toward the environment but also the social structure to a degree. It would be interesting to this technique applied to other countries today to see how these values have changed and reveal what forces are driving development and change today.

  3. Cool blog. I wonder if climate change has changed the area's production and if researchers can update their project using GIS to model agricultural output. Furthermore, GIS can be used to guide farmers to cultivate the most productive areas while lowering costs, such as irrigation, leakage, and transportation. GIS spatial modeling may even illustrate runoff pollution from agricultural activities.