Geography Reference
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Figure 7.7 Zokor density (as indexed by dirt mounds they produce) as a function of domestic
sheep density.
2000
1600
1200
800
400
0
0
1
2
3
4
5
6
7
From: Fan et al. 1999
Sheep / Ha / Yr
Source: Adapted from Fan et al. 1999.
the zokor's fossorial nature) and one often ended up with an increased zokor population
(see Figure 7.7). 87 Finally, if in fact the underlying premise regarding cause and effect
was reversed, it can easily be seen that temporary reduction would have had little effect.
If instead of causing grassland degradation, high densities of these species were primarily
a response to existing habitat conditions, then failing to address those conditions simply
left the surviving animals in a veritable paradise: the same, ideal habitat but with that
many fewer conspecific competitors. 88
As research on these species progressed (driven, it can safely be assumed, primarily
by the incentive to kill them more efficiently) and Chinese scientists became increasingly
knowledgeable about ecology and correspondingly less influenced by Maoist ideology,
understanding of the biology deepened. It began to emerge that both species had impor-
tant roles as ecological engineers within the plateau ecosystem, and that a host of plant
and animal species were closely associated, and perhaps even wholly dependent, on the
activities of pikas and zokors. 89 By the late 1990s, it had become widely acknowledged
that pikas in particular (and zokors to a lesser extent) are the architects of unique micro-
ecosystems, and that their loss in any given area would therefore be manifested in a cascade
of other ecological changes. In particular, a number of bird species find shelter or nesting
spots only in the burrows of plateau pikas. One species in particular, the Hume's ground
jay, appears to find acceptable habitat only within pika colonies; an obligate commensal,
it is essentially absent lacking pikas. 90 In addition, pikas form the primary food resources
 
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