Fig 1.
Illustration of the distribution of rock outcrops and soil patches in karst area.
Soil patches can support the growth of vascular plants, while various outcrops can receive and redistribute atmospheric water and nutrients to soil patches.
Table 1.
General features of the sampled outcrops and the tree canopy coverage.
Fig 2.
(a) Collection systems for rock runoff water; (b) collection systems for input water falling on rock surface; (c) determination of rock projected area, and (d) sampling of epiliths.
Table 2.
Summary of collection time, volume, number, and chemical analyses for samples.
Fig 3.
Organic carbon and nutrient concentrations (mean ± standard error) in input water.
RDE, AFE, SFE are as defined in the text. Different lowercase letters indicate significant differences between two systems (P<0.05); different uppercase letters indicate significant differences between two seasons (P<0.05) in the same ecosystem.
Fig 4.
Organic carbon and nutrient concentrations (mean ± standard error) in exported water.
All designations are as above, except * represents a significant difference (P<0.05) between input (Fig 3) and export.
Table 3.
Factors correlated with organic carbon and nutrient concentrations in outcrop runoff water and their significance levels at different times.
Table 4.
Annual TOC and nutrients received by rock outcrops and exported to nearby soil patches per m2 of rock projected areas (mean ± standard error) in the three karst ecosystems.
Table 5.
Ratios of the annual input of total organic carbon (TOC) and nutrients per m2 of rock projected area (INP) to those of the epiliths pool (POOL), ratios of annual runoff exportation of TOC, and nutrients per m2 of rock projected area (EXP) to those of the annual input (INP) for the three ecosystems.
Table 6.
Estimated ratios of TOC and nutrients received annually from rock runoff water to those received from atmospheric deposition by soil patches with different outcrop to soil area ratios (R/S) in the three ecosystems.
Fig 5.
Theoretical model showing the amounts of organic matter and nutrients received by soil patches from atmospheric deposition and from rock outcrops’ runoff along an outcrop’s proportion gradient.