Why do long droughts reduce biological productivity in arid and semiarid ecosystems?

In arid and semiarid ecosystems, biological productivity is fundamentally dependent on the availability of moisture. Because these environments are characterized by naturally sparse and variable rainfall, they are highly sensitive to climatic fluctuations.12

Long droughts reduce biological productivity because they deprive plants of the essential water required for growth. In these regions, vegetation typically relies on occasional moisture inputs to thrive; when extended droughts occur, the lack of water prevents this growth, leading to a rapid decline in overall productivity. While these ecosystems are capable of recovering during wetter periods, prolonged drought conditions can lead to lasting damage, such as the loss of perennial plant cover and reduced woody biomass. This reduction in plant life further exacerbates the stress on the environment, as the loss of vegetation cover diminishes the soil fertility typically maintained by shrubs and their associated microbial communities.12