In a week, growing vegetation(visible JK circled) reveals several such wildlife runs as this.
Disturbance of soil and of knotweed growth is active and current at time of compilation(May 2012).
If one adds the incidences of wildlife "traffic" and disturbance to daily human interaction, then one will expect the result to be constant, aggressive and vigorous JK spread and growth.
It is this consequence that is recorded within these images...the time between cause and effect is dramatically small, when applied to Japanese knotweed.