Double Exposure

A trove of photographs taken by a legendary plant hunter is providing a unique look at environmental change in western China over the last century. By revisiting spots where Ernest Henry “Chinese” Wilson took his snaps in the early 1900s, Chinese researchers have been able to document “remarkable” climate shifts and ecosystem changes.

Wilson, an English botanist born in 1876, traveled to western China five times from 1899 to 1918, a research team reports in PLoS ONE. He collected about 65,000 plant specimens – and took more than 1,000 photos, mostly between 1908 and 1910. In 1997, researchers began collecting the old pictures, and in 2004 embarked on a 7-year odyssey to revisit the spots where Wilson snapped 250 of the images. Then, they compared their photos with Wilson’s.

The images revealed “an obvious warming trend over the 100 years, not only in specific areas but throughout the entire Western China,” they write. Snow packs had disappeared from some alpine scenes, for instance. And “we also noted remarkable vegetation changes. Out of 62 picture pairs… 39 indicated vegetation has changed to the better condition, 17 for degraded vegetation and six for no obvious change.” Forests have replaced farmlands in some areas, for instance, although they also showed alpine meadows degraded by overgrazing. (Click here to see the picture pairs.)

The pictures also highlighted rapid urbanization, and “also the disappearance of traditional cultures.” Some towns photographed by Wilson, however, had been completely destroyed by earthquakes.

There’s also a lesson to be seen, the researchers conclude. “The historically ecological changes in the past century of Western China inform us that sustainable development is possible in such a human dominated vulnerable region,” they write, although “there are many great challenges to approach the balance of development and protection.” David Malakoff | October 1, 2011

Source: Chen, H., Yin, K., Wang, H., Zhong, S., Wu, N., Shi, F., Zhu, D., Zhu, Q., Wang, W., Ma, Z., Fang, X., Li, W., Zhao, P., & Peng, C. (2011). Detecting One-Hundred-Year Environmental Changes in Western China Using Seven-Year Repeat Photography. PLoS ONE, 6 (9) DOI: 10.1371/journal.pone.0025008

Image Wikimedia Commons

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