Figure 1The
structure of intransitive networks could be divided into five simple
forms: short loop (a), nested loop (b), long loop(c), independent
loop(d) and cross loop(e). The big brace means that the networks have
nested loop always along with structure of long loop, independent loop
or cross loop. Nodes in network represent species (letters), and red
arrows point to less competitive species.
The
structure of the intransitive network was divided into five simple
forms: short loop (only one loop of three species, in Fig. 1a), nested
loop (a large loop embedded with a small loop in Fig. 1b), long loop
(all species fall into the loop, in Fig. 1c), independent loop (there
are at least two loops, and no species shared in them, in Fig. 1d), and
cross loop (at least two loops with shared and unshared species, in Fig.
1e). In the real plant community, the competitive relationship among
species was very complex, and its competitive structure was often not a
single structure. In the sample plots investigated, there were six kinds
of loop-structure combinations of the five simples (in Tab.1), among
which the short network, accounting for 23.04%, while the nested
network, accounting for 76.96%, in 191 intransitive networks. The short
network and the nested network are mutually exclusive, representing
relatively simple network and more complex one, respectively.
Table 1 The kinds of combination of the simple loop structures are
distributed. The short network, accounting for 23.04%, only contains
short loop. The nested network, accounting for 76.96%, contains
combination of other simple structures in addition to nested network,
and there were five kinds of such combinations.