To comparatively investigate the stoichiometric characteristics of carbon (C)

nitrogen (N)

and phosphorus (P) in plant organs and soil layers of coniferous forests

we conducted plot surveys in five prefectures/cities (Tianshui

Gannan

Dingxi

Lanzhou

and Wuwei) in Gansu Province on western Loess Plateau. Contents of C

N

P

and their stoichiometric ratios in each plant organ and different depth of soil layers were analyzed

the relationships among components in the coniferous forest ecosystems were analyzed and compared across the five study areas. The results showed that C

N

and P contents in the foliage were higher than in other organs of the trees

and C content reached 511.97-538.66 g/kg. The C content in stems

branches

and roots in Wuwei was 425.04 g/kg

400.58 g/kg

and 400.55 g/kg

respectively

being significantly lower than those in the other four areas. The differences in C:N among study areas were only significant for stems (p < 0.05). Significant differences in C:N among different organs of the conifers were found in Gannan and Lanzhou. The N:P in stems and roots of the conifers were significantly different among study areas

whereas the differences in N:P among organs were only significant in Lanzhou and Wuwei. Differences in the contents and stoichiometric characteristics of soil C

N

and P among the five survey areas were mainly detected in the 0-30 cm soil layers

while the deeper soil layers showed little difference among study areas. In addition

C

N

and P contents in stems of the conifers were significantly correlated with each other

while a significant correlation was only detected between N and P contents in leaves. Soil C and N contents in the surface layer (0-20 cm) showed a significant positive correlation.