In order to understand the influence of ecological restoration models on the exchange and distribution of soil base ions in the karst mountain area

the typical yellow rendzina was taken as study object and the effects of ecological restoration pattern

which including arable land (AL)

Grassland (GL)

the intercropping system of forest and grass (ICS)

and the grassland converted from cropland (CGL)

on the cation exchange capacity (CEC) and the exchangeable base contents were studied. The results showed that the CEC vary between 26.52 and 44.90 cmol/kg and decreased with the increase of profile depth. CEC of each soil layer was significantly lower in CGL than in ICS

GL

and AL (P<0.05). The CEC of ICS was the highest in 0—10 cm and 10—20 cm soil layers. The size order of exchangeable base cations was Ca2+ > Mg2+ > K+ > Na+

and Ca2+

Mg2+ were the major exchangeable bases

because Ca2+

Mg2+

K+

and Na+ accounts for 91.92%

6.04%

1.03%

and 1.01% of the total content of exchangeable bases

respectively. The contents of Mg2+

K+

and Na+ were higher in the surface layer than those in deeper layers and decreased with the increase of soil depth regardless of restoration patterns. Under different ecological restoration modes

the content of each base ion in CGL was significantly lower than in ICS

Al and GL (P<0.05)

but the content of each base ion varied with the soil depth. The distribution rule of soil total exchangeable base (TEB) was not obvious at the soil depth. The order of soil TEB in different ecological restoration modes was different with the increase of profile depth

in 0—10 cm

10—20 cm soil layer

and 40-60 cm (mother rock) layer

GL was the highest and CGL was the lowest. The soil base saturation (BS) in this area changed between 42.58% and 65.02% and gradually increased with the increase of soil depth. BS were the largest in GL

and followed by those in AL

ICS

and CGL. Correlation analysis showed that CEC

base ion content and organic matter

total nitrogen and alkaline nitrogen were all significantly and positively correlated. Redundancy analysis (RDA) shows that soil physical and chemical factors could only explain 45.3% of the changes in cation exchange. The changes in soil cation exchange were affected by other factors besides the basic physical and chemical factors. In general

CGL was significantly lower than other recovery models in the ability of fertilizer supply and buffer and GL had better performance. In the early stage of restoration

the soil fertility and buffer capacity decreased

but it will be improved gradually with the process of ecological restoration.