The maximum generalized entropy principle demonstrates that a
sediment-starved clear freshwater ecosystem is stabler but more
susceptible to being affected than a sediment-laden turbid system
Abstract
Different types of rivers have their own ecosystems. Based on the
laden-starved sediment content in rivers, they can be classified as
sediment-laden turbid (SLT) and sediment-starved clear (SSC) river
ecosystems. Understanding the evolution process and driving factors of
these two river ecosystems is very important for the protection of their
ecology. Until now, however, there has been no comprehensive study that
integrates biological and nonbiological factors in river ecosystems.
Here, the self-organizing feature map (SOFM) model based on the maximum
generalized entropy principle can integrate the two and conduct research
on the evolution of river ecosystems. First, we can evaluate the
stabilities of the SLT river ecosystem (i.e., the Weihe River
mainstream) and the SSC river ecosystem (i.e., the Weihe River
tributaries at the northern foot of the Qinling Mountains). Second, the
degree of influence of various factors on stability was assessed.
Finally, correlation analysis was added to study the driving
relationship between the internal and external aspects of the ecosystem.
The results showed that the stability of the SLT river ecosystem (mean
value 3.371) was lower than that of the SSC type (mean value 5.343).
However, the SSC river ecosystem was more susceptible to being affected
because more factors could affect its stability. Further study indicated
that although turbidity was the largest connection weight in the two
river ecosystems, the reasons for its increase were different. This
result was due to the increased sediment content in the SLT river
ecosystem and the growth of algae in the SSC ecosystem. The main reason
for this difference was that the SLT and SSC river ecosystems had
different external driving forces. The SLT river ecosystem was mainly
driven by land utilization, and the SSC was mainly driven by
hydrological situations and climate factors. Although there are
differences between the two ecosystems, they may transform into each
other when the external driving force of the river ecosystem changes.
This study emphasizes the importance of external background to the
evolution trend of river ecosystems and the difference in the influence
of internal factors on the stability of river ecosystems.