CHINA’S WILD WEST - Wildlife Conservation in China: Preserving the Habitat of China's Wild West - page 29

Table 2.1

Weather Stations Used for Assessment of Climatic Trends in the Study Area

Station Name Distance from Study Area Center Elevation (m) Years of Data

Da Qaidam approx. 110 km south 3173 1957-1993

Dulan approx. 355 km southeast 3191 1954-1998

Dunhuang approx. 165 km north-northwest 1139 1962-1993

Jiuquan approx. 270 km northeast 1477 1935-1998

Lenghu approx. 195 km west-southwest 2733 1957-1993

Qilian Tuole approx. 250 km east 3360 1957-1993

Yumen approx. 210 km northeast 1526 1953-1993

If, on the other hand, there is a common perception that precipitation has decreased
when in fact it has not , the implications are quite different. If ground water reservoirs are
drying up, subirrigated pastureland is decreasing in area, and formerly roiling rivers are
evolving into mild rivulets in the absence of any reduction in actual precipitation, the most
parsimonious explanation is that humans have been using surface water faster than it is be-
ing replenished. If local pastoralists are convinced that “it rains less than it used to” when,
in fact, accumulated rainfall assessed over the long term has remained constant, they are
probably reacting to declines in vegetation abundance or vigor whose causes lie elsewhere,
most likely in excessive use by livestock. Thus it is worth taking a small detour into the
world of meteorology and hydrology to examine these claims in more detail.
One would think that, with the seeming unanimity of wisdom that China's west has
been getting drier, it would be easy to find solid evidence in the form of weather records
(which are, in contrast to biological data, relatively straightforward to obtain and interpret).
But strangely enough, the evidence of reduced precipitation simply isn't there. In most
cases, weather records show no discernible change in precipitation amounts over the past
few decades. In the few places where changes appear to have occurred, data indicate a
trend toward a wetter climate, not a drier one.
For example, during our investigations into possible wildlife/livestock conflicts in Aksai
County in western Gansu, we frequently heard pastoralists complain that the climate had gotten
drier since earlier times. 19 This view was shared by one of Gansu's foremost wildlife experts
who, as luck would have it, had lived in Aksai some two decades earlier and had supervised
the vegetation study that, at least nominally, justified the livestock carrying capacity limits and
household allotments that were implemented in the early 1980s. There was little doubt that
vegetation conditions had worsened over time, but how much, if any, of that trend could be
attributed to climatic factors? To find out, we obtained monthly precipitation records through
1993 for the seven weather stations surrounding our study area that had been vetted as most
likely to be accurate by a joint Chinese-American meteorological program. 20
The weather stations that were available and used for the analysis are listed in Table
2.1. In general, there is no evidence of substantial changes in precipitation amounts over
the time-period for which data are available (Figure 2.6). Of the seven stations, two show
significant ( P < 0.05) trends of yearly precipitation on time, and both are positive (Dulan,
about 1.2mm/year, and Qilian Tuole, about 1.5mm/year).