Role of Bryophytes in Ecology and Plant Succession

The ability of bryophytes to stabilize soil, to trap and hold moisture, to exchange cations, and to tolerate desiccation together with their high totipotency makes them a very important contributor in plant succession and ecology.

Succession is an orderly sequence of changes in an open habitat in which organisms interact with the environment for development of a stable and climax community.

Plant succession taking place on a particular habitat is called a sere, its various intermediate stages are called seral stages, and the communities representing the stages are called seral communities.

The importance of bryophytes in ecology and plant succession is outlined below: 

As aids in soil conservation: 

Mosses prevent sheet erosion of soil. They grow densely forming a mat or carpet-like structure. It bears the impact of the falling raindrops, holds much of the rainwater, and thus the amount of run-off water is considerably reduced. The intertwined moss stems and the underground rhizoids firmly binds the soil particles together to a considerable depth of around 6 to 8 inches. This minimizes soil erosion even on steep hill sides.

Formation of soil and vegetation cover: 

In a xeric succession which begins on a bare rock surface the bryophytes, mosses in particular, form an important seral community. The bryophytes and the lichens in the primary succession led to soil formation through accumulation of organic matters and prepare rocky out crops for secondary succession of herbs, shrubs, and trees. The pioneer community is the crustose lichen and followed by the first seral community, the folios lichen. Acid secreted by lichens attack the rock and provide bits of soil. Additional soil particles maybe formed by weathering or be blown in from somewhere else. Thus, the accumulation of soil particles, organic matter, and humus results in the development of a fine soil layer over the underlying rock. This favors the entrance and colonization of mosses, thus beginning the moss stage.

Funaria hygrometrica is the first to colonize the high pH and high potash substratum. It is followed by Polytricum juniperinum, P. piliferum, Ceratodon sp., Tortula sp., and Grimmia sp. These mosses have an added advantage due to presence of minute green leaf-like structures with accelerated photosynthesis and presence of slender multicellular branched rhizoids that compete with folios lichens for absorption of water and nutrients. The increased rate of photosynthesis and absorption produces organic matter at higher pace thus accelerating the soil formation process.

Bog succession: 

Mosses play an important role in bog succession from open water to climax forest. Moses, like Sphagnum, grow over the water surface with their intertwined stems forming a thick mat together with the dead and partiality decayed gametophytic tissue. This provides a substratum for the germination of seeds or propagules of many floating and rooted hydrophytes. In course of time the partially decomposed Sphagnum and the hydrophytes form a dense surface covering over the water forming the so-called quacking bogs. Later bogs are converted into swamps capable of supporting relatively large trees and eventually such swamps are replaced by forest growth. The 'feather mosses' like Hylocomium splendens and Thuidium delicatulum, serve as seed beds for native forest trees and wildflowers.

Rock builders: 

Certain mosses growing in association with other aquatic plants contain large amount of calcium carbonate. The plants bring about decomposition of bicarbonate ions by abstracting free carbon dioxide. The insoluble calcium carbonate precipitates and hardens, forming calcareous rock like deposits. This deposition grows and extends over areas of several 100 square feet. This travertine rock deposits are extensively used as building stone. 

Peatland ecology:

Bryophytes play an important role information of peatland. The factors for the development of peat as follows:

Nutrient absorption capacity: Nitrates and phosphate are the limiting factors in peat formation. Bryophytes can absorb nitrates and phosphate very easily then other vascular plants. 

Water holding capacity: Bryophytes can absorb water and hold it for longer period of time. Some morphological structures help them in this purpose. This enables continuous photosynthetic activity even in the dry season. 

Decomposition: In peat and, growth rate of peat moses is greater than their decomposition rate. This happens only if there is oligotrophication.

Acidification: Some peat moses like Sphagnum secret uronic acids. Protons are liberated from the uronic acid resulting in acidification of the environment.

Water Retention and Purification:

Bryophytes have the ability to absorb and retain large amounts of water, helping to regulate water cycles. They also aid in purifying water by filtering out impurities and excess nutrients.