A global meta-analysis of changes in soil carbon, nitrogen, phosphorus and sulfur, and stoichiometric shifts after forestation

Planted forests, established on non-forest lands, play an important role in enhancing terrestrial carbon (C) sequestration. Understanding the changes in soil C, nutrients and stoichiometry in planted forests is important for forest management. We conducted a global meta-analysis of changes in C, nitrogen (N), phosphorus (P) and sulfur (S) and their stoichiometry in mineral soils of planted forest across broad climatic zones from 139 papers. Soil C and N are slightly decreased after forestation on grassland, moderately increased after forestation on cropland, and substantially increased after forestation on barren land. Forestation does not affect total soil P, but the available P is significantly depleted after the forestation of grassland and cropland with N-fixers. Changes in soil nutrients (N, P and S) and shifts in stoichiometry (ratios of C:N, C:P and N:P) are significantly related to soil C dynamics (p < 0.05). Soil C sequestration is the lowest in the boreal zone, and greater under plantation with N-fixing species than under non-fixing species. Changes in soil C and nutrients after forestation mainly differ to prior land use. Compared with forestation of grassland, forestation of barren land is a more effective approach to enhancing C sequestration.