The effect could be physical instead of chemical.
I don't know the termes in English, so I shall use common words.
Each plant has a strength to take water out of the dirt.
When the water in the dirt goes down the plant takes less and less water. When the plant reaches its limit,it wilt. Then the quantity of water in the soil decreases slowly because the plant doesn't take anymore significant quantity of water.
Succulent plant have much higher strength to take out water.
If you put a succulent at the same place the quantity of water will decrease faster and shall not slow down when the citrus reaches its limit, "over drying" the dirt.
The stress is much stronger than without the succulent, provoking a strong bloom ( wich, as said before, is not always a good sign).
Here I see the limit of my English...