Ecology of hemiparasitic Orobanchaceae with special reference to their interaction with plant communities

Abstract

A parasite species has multiple roles in its habitat at the individual and the plant community levels, as deduced from studies on model hemiparasitic species. A parasite population can reduce the overall productivity and fecundity of susceptible species while fostering resistant species. For example, the population of forbs can increase at the expense of Rhinanthus-susceptible grasses. Reduction in host productivity by the parasite is due to both resource abstraction and suppression of host photosynthesis. Mathematical modelling described the spatio-temporally dynamic negative feedbacks between parasite and host community that can result in cycling of community composition. Parasites can also be active in nutrient recycling in the plant community. Other interactions are less obvious. The parasites interact with soil microorganisms, may benefit from host association with mycorrhizal fungi and may interact directly and indirectly with other organism including pollinators.