Stages in the Terraforming of Mars: the Transition to Flowering Plants

Abstract

The process of the biological terraforming of Mars can be compared to the process of primary ecological succession on terrestrial barren rocks. Each stage in the succession alters the environment in such a way that the next stage in the process becomes possible. The initial stage in terraforming Mars will be dominated by microorganisms and lichens. The initial stage will begin the process of removing carbon dioxide from the Martian atmosphere, adding oxygen and nitrogen, and adding organics to the regolith to produce a true Martian soil. The second stage will be dominated by bryophytes, simple plants such as mosses and liverworts, which will draw down the carbon dioxide level of the Martian atmosphere and raise the level of oxygen. The carbon dioxide removed will be locked up in peatlands and permafrost. The critical limiting factors for the introduction of flowering plants are the level of oxygen in the atmosphere and the lack of animal pollinators. The majority of flowering plants require a minimum oxygen level of 20 to 50 mbar. Most flowering plants require these minimal oxygen levels to support aerobic respiration in their roots and germination of their seeds. Many flowering plant species also must have animal pollinators to complete reproduction. Certain aquatic plants and arctic plants, however, are highly tolerant of anoxic conditions. Some of these same arctic plants can successfully reproduce without animal pollinators by employing one or more alternate reproductive mechanisms such as vegetative propagation, apomixis, autogamy and anemophily. Thus by judicious selection of existing terrestrial plants and possibly genetic engineering, it may be possible to circumvent critical limitations and introduce flowering plants to Mars at an earlier stage in terraforming.