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The growth process, palaeoecological features and the function of organisms in reef-building of the Jukoupu bioherm in Hunan are discussed in detail. The bioherm is divided into 10 micro facies. Organisms are very abundant in the reef. Thirty-two genera belonging to 7 phyla have been recognized. They make up 5 communities composed mainly of stromatopoids, corals and algae, each of which has its own salient ecological features. An analysis of all communities shows that the organic functions are very complex. The same organisms may possess diverse functions simultaneously as the reef growth enters the late stage. The growth process of the reef may involve five stages: (l) biostrome stage, (2) stabilization stage, (3) frame-type reef-building stage, (4) binding and covering-type reef-building stage, and (5) baffle-type reef-building stage.

Phylloid algae are important reef-builders in the late Carboniferous. This paper focuses on the paleoecology of phylloid algae in the Late Carboniferous on well-exposed reefs in Ziyun County, Guizhou Province. Phylloid algae growing closely packed are attached via holdfast or similar structure to substrate. They were growing in environments such as shallow water, photic zone and below the wave base with medium energy currents. They have a variety of morphological forms, such as single cup-shaped, cabbage-shaped and clustering cup-shaped. The thalli are of certain tenacity and intensity. In the areas dominated by phylloid algae, other marine organisms are relatively scarce. Obviously, phylloid algae are stronger competitors for living space than other co-occurring organisms.

Pennsylvanian phylloid algal reefs are widespread and well exposed in south Guizhou, China. Here we report on reefs ranging from 2 to 8 m thickness and 30–50 m lateral extension. Algae, the main components, display a wide spectrum of growth forms, but are commonly cyathiform (cup-shaped) and leaf-like (undulate plates). The algal reef facies is dominated by boundstone. Algal thalli form a dense carpet whose framework pores are filled with marine cement and peloidal micrite. The peloidal matrix is dense, partly laminated or clotted with irregular surfaces and often gravity defying. Algal reefs in Guizhou differ from examples reported to date by the high biodiversity of organisms other than phylloids: e.g., the intergrowth of algae with corals (some of which are twice the size of algal thalli) and numerous large brachiopods. This contrasts to previous views that phylloid algal “meadows” dominated the actual seafloor, excluding other biota. Also, the pervasive marine cements (up to 50%) including botryoidal cement are noteworthy. Algal reefs developed at platform margins, a depositional environment similar to that of modern Halimeda mounds in Java, Australia and off Bahamas, and to that of time- equivalent examples reported from the Canadian Arctic Archipelago. Whereas nutrients appear decisive in the growth of Halimeda reefs, algal reefs reported herein seemingly grew under conditions of low nutrient levels. Overall, algal reefs in Guizhou challenge previous views on growth forms, diversity patterns, and depositional environments and add to the spectrum of these partly puzzling biogenic structures.