Theory 40/Desert & Dryland/Woody encroachment
Shrubs Take Grazing Gaps
The claim
Woody encroachment in drylands follows a threshold in grazing removal, because grass roots are what exclude shrub seedlings from surface water.
01Mechanism
Grasses intercept infiltration in the upper soil; when removed, water reaches deeper and favours shrubs.
02Prediction
Encroachment should track grazing pressure.
03Refutation
Encroachment tracking rainfall would remove competition.