Variation of vegetation coverage and canopy height may reflect the complex spatial heterogeneity
of nutrient storage and supply capacity, soil moisture, and surface hydrology in the karst terrains
suffering from severe land degradation. To assess the patterns of nutrient limitation under different
vegetation covers in the subtropical karst ecosystems from Guizhou province, southwestern China,
topsoil and leaf samples of dominant treespecies were collected in forest stand (FO), shrub stand
(SH) and shrub-grass stand (SG), respectively. Nutrientconcentrations of both soil and leaf were
determined, and ratios of N to P and vegetation nutrient reuse capacity (VNR) calculated as well
as vegetation coverage, vegetation canopy height and tree density measured across the three stands.
Mean leaf N/P ratio was lowest (16.1 ± 1.4) in FO and highest (33.5 ± 3.2) in SG. Vegetation
nutrient reuse increased with the decline in N and P availability in soils for these three stands.
VNR of N and P ranged from 8.5 to 25.2 mg N g-1 and from 0.4 to 1.1 mg P g-1,respectively, and
appeared lowest in SG (10.4 mg N g-1and 0.5 P mg g-1 on average, respectively) and highest in
FO (22.4 mg N g-1 and 0.9 mg P g-1 on average,respectively). Although there was no substantial
difference in phosphorus reuse efficiencies between plant species and vegetation stands, concentra-
tions of N and P of senesced leaves (SLs) were, respectively, found in positive correlation with the
concentrations of mature leaves. The variation of VNR with elements indicated that P is cycled within
vegetation much more efficiently than N across the stands.This study demonstrated that the karst
vegetations were generally at P-limited or N- and P- co-limited stresses andthat N/P ratio could be
an effective indictor for nutrient limitation in the karst ecosystems at vegetation community level
rather than at tree species level. It is proposed thatphosphorus reuse by mature leaves could be an
adaptation strategy by the dominant species to the low P availability in the karst soil.