What triggers dormancy in a palo verde

Freeze and Drought

Explanation:

During times of drought, the palo verde's leaves may turn yellow to brown and fall off. ... This is a natural process that does not indicate harm or disease -- thanks to the green bark of the palo verde, photosynthesis can continue after the tree sheds its leaves.

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.