Abstract
We determined the influence of nutrient availability on the mechanisms used by plants to acquire nitrogen and phosphorus from the soil. Extracellular acid phosphatase production, mycorrhizal colonization, and N and P uptake capacities were measured in control, N-, and P-fertilized forests in three sites that varied in nutrient status from N limited to relatively fertile to P limited. Nitrogen fertilization increased extracellular phosphatase activity in all sites. Phosphorus additions consistently reduced phosphatase activity, mycorrhizal colonization, and P uptake capacity across sites. Our results indicate that these plants efficiently allocate resources to nutrient acquisition as suggested by an economic model. Investment in acquisition of a nutrient was greatest when that nutrient was limiting to growth, and plants appeared to allocate excess N to construction of extracellular phosphatases to acquire P. This increase in phosphatase production with N fertilization implies that even P-limited systems might respond to N deposition with greater productivity.
Highlights
Nitrogen and phosphorus, either individually or in combination, limit primary productivity in most terrestrial ecosystems, and investment by plants in acquisition of these soil nutrients can have important implications for plant growth and nutrient dynamics
We examined the potential of ecosystems to modify allocation of resources among several nutrient acquisition mechanisms in response to N and P availability
Roots were collected in October 1997 for analyses of extracellular phosphatase; in January and March 1996 and July and October 1997 for mycorrhizal colonization; in June 1998 for P-uptake capacity; and in May 1998 for N-uptake capacity
Summary
Either individually or in combination, limit primary productivity in most terrestrial ecosystems, and investment by plants in acquisition of these soil nutrients can have important implications for plant growth and nutrient dynamics. Economic-based theories suggest that plants optimize growth by allocating more reserves to the acquisition of nutrients that most limit growth (Bloom et al 1985, Read 1991). It follows that plants may use resources that are available in excess to capture those that are not. Because nutrients interact in this manner, it is important to consider the availability of several essential resources (e.g., C, N, and P) simultaneously to adequately assess regulation of N and P acquisition by plants
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
