Nitrogen and phosphorus status and their influence on aboveground production under increasing nitrogen deposition in three successional forests

Relationships of phosphorus fractions to organic carbon content in surface soils in mature subtropical forests, Dinghushan, China

“…The results did not support the hypothesis that continuous accumulation of soil organic C could essentially lead to binding of the P pool, thus reducing soil P availability and leading to P limitation on plant growth (Schlesinger et al 1998;Huang et al 2012). Soil extractable Po (Al-Po and Fe-Po) contents might linearly increase with the accumulation of soil organic C, but the increased soil extractable Po was not transferred from soil extractable Pi (soluble Pi, Al-Pi and Fe-Pi) or residual Pi or Po fraction in the surface soil.…”

“…This result seems inconsistent with the study by Zhou et al (2006), which reported that surface-soil organic C stock accumulated rapidly at site 5 between 1979 and 2003. However, it is possible that soil organic C content at all study sites had accumulated at a high rate, possibly due to the continuously high atmospheric N deposition (~40 kg N/ha.year) (Mo et al 2008;Huang et al 2012) rather than to the stand development. Gleixner et al (2009) reviewed soil C stock changes with stand development in many biomes and found that chronosequence estimates of soil organic C accumulation (-4.5 to 17.6 g C/m 2 .year) were generally much lower than the estimates based on repeated sampling (32-165 g C/m 2 .year).…”

“…Recently, Huang et al (2012) proposed that the continuous accumulation of soil organic C might have occluded P in its organic form, thereby decreasing soil P availability in forest ecosystems in this area, as the site with a relatively higher soil organic matter pool possessed a relatively lower soil soluble P pool.…”

“…It can also maintain soil P availability by providing binding sites (Kang et al 2009). However, some studies have suggested that an accumulation of soil organic C (or organic matter) may decrease soil P availability due to the inclusion of P in organic form (Huang et al 2012;Schlesinger et al 1998). For example, Schlesinger et al (1998) proposed that P was limiting plant growth in soil at an early stage of development (110 years) on Rakata Island, Indonesia, perhaps as a result of the observed rapid accumulation of organic P. Wang et al (2006) found that soil organic C concentration was positively related to the concentrations of soil soluble organic-P fractions, whereas it was negatively related to the concentrations of soil soluble inorganic-P fractions in depressional and riparian freshwater wetlands in North-east China.…”

Human-induced nitrogen–phosphorus imbalances alter natural and managed ecosystems across the globe

“…Increases in nitrogen deposition have also been observed in some tropical regions 10 , areas that, despite being complex and heterogeneous, are usually less nitrogen-limited than temperate regions. Some recent studies have already observed increases in soil N:P ratios due to N deposition in tropical forest 11 .…”