Ecosystem Nutrient Use Efficiency, Productivity, and Nutrient Accrual in Model Tropical Communities

• Published in: Ecosystems (New York) Vol. 4; no. 7; pp. 669 - 682
• Main Authors: Hiremath, Ankila J., Ewel, John J.
• Format: Journal Article
• Language: English
• Published: New York, NY Springer-Verlag 01-11-2001; Springer; Springer Nature B.V
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biodiversity; Biological and medical sciences; Ecological function; Ecosystems; Forest soils; Fundamental and applied biological sciences. Psychology; Monoculture; Nutrient availability; Nutrient retention; Nutrient uptake; Nutrient use efficiency; Nutrients; Plant species; Plants; Polyculture; Productivity; Soil ecology; Soil nutrients; Species; Species diversity; Synecology; Terrestrial ecosystems; Productivity; Primary productivity; Ecosystem; Nutrient recovery; Tropical zone; Mixed farming; Nutrient; Models; Ecosystem functioning
• ISSN: 1432-9840; 1435-0629
• DOI: 10.1007/s10021-001-0036-x

Ecosystem nutrient use efficiency-the ratio of net primary productivity to soil nutrient supply-is an integrative measure of ecosystem functioning. High productivity and nutrient retention in natural systems are frequently attributed to high species diversity, even though some single-species systems can be highly productive and effective at resource capture. We investigated the effects of both individual species and life-form diversity on ecosystem nutrient use efficiency using model tropical ecosystems comprised of monocultures of three tree species and polycultures in which each of the tree species was coplanted with species of two additional life forms. Tree species significantly influenced nutrient use efficiency by whole ecosystems in monocultures; however, in polycultures, the additional life forms interacted with the influence exerted by the dominant tree. Furthermore, the presence of the additional life forms significantly increased nutrient uptake and uptake efficiency, but in only two of the three systems and 2 of the 4 years of the study period. These results indicate that the effect of lifeform diversity on ecosystem functioning is not constant and that there may be temporal shifts in the influence exerted by different components of the community. Furthermore, although species (and life forms) exerted considerable influence on ecosystem nutrient use efficiency, this efficiency was most closely related to soil nutrient availability. These findings demonstrate that ecosystem nutrient use efficiency is an outcome not only of the characteristics of the species or life forms that comprise the system but also of factors that affect soil nutrient supply. The results argue against the simple upward scaling of nutrient use efficiency from leaves and plants to ecosystems.