5. Conclusions and implications
1. Human land-use activitieswere associatedwith lower soil N concentrations
and higher total soil K and available-P concentrations.
2. The stoichiometric changes and their relationships with other soil
properties such as soil respiration suggest the limitation of N in the
ecosystems of this estuary. A soil N:P ratio lower than global ratios
and a lower soil N concentration in rice cropland despite N fertilization
also suggest N limitation.
3. Anthropogenic transformations of land use were associated with a
lower available N:P ratio, an effect related to increases in fertilization
under a natural N limitation and also in accordance with the lower P
solubility than N and with the tendency of human activities to favor
more-productive ecosystems with low N:P ratios able to support
species with high rates of growth.
Conflict of interest
There is no conflict of interest.
Acknowledgment
This work was supported by grants from the National Science
Foundation of China (31000209), Spanish Government grants CGL2010- 17172/BOS and Consolider-Ingenio Montes CSD2008-00040, Catalan
Government grant SGR 2009-458 and European Research Council
Synergy grant ERC-SyG-2013-610028, IMBALANCE-P.