Acid rain is a complex phenomenon that can result either from natural or anthropogenic causes. Within the broad term “acid rain” several different processes can be grouped, namely acidic rain, fog, hail and snow. These processes affect nearly all ecosystems within its reach, from marine to terrestrial ones.
In particular, the negative impact of acid rain in terrestrial ecosystems arises both from its deleterious effects on soil and from a direct effect upon plant organs, such as leaves and roots.
In this chapter, the major consequences of acid rain on soils will be discussed, mainly focusing on the chemistry of nitrogen, oxygen and sulphur that is involved in nutrient depletion and transformation.
The impact of acid rain in the physiology and anatomy of several species with economic importance will be presented, with particular emphasis in plant seedlings, plants’ growth and life cycle. The physiological responses of plants to acid rain, and the signalling pathways involved will also be considered.