『Abstract
Pines (Pinus sylvestris L.) have been widely used for
monoculture forest stands in north-eastern Germany. However, several
studies have discussed the need to convert monoculture into mixed
forest stands such as pine-oak forest. In this study, we evaluated
the impact of 102 years-old pine (P. sylvestris L.) in
monoculture and mixed forest stands of P. sylvestris +
Quercus petraea (Matt.) Liebl. of different ages (10.35,
106 and 124 years-old) on the dynamics of soil organic phosphorus
(Po) pools. The study was carried out in the Northern Germany
Lowlands of Brandenburg. Soil samples were taken from forest floor
and two mineral soil layers at the depths of 0-10 and 10-20 cm.
Different P forms of the sandy soil were obtained by sequential
P fractionation, using acid and alkaline extractants. The soil
total P (STP) ranged from 100 to 183 mg kg-1 whereas
total organic P (TPo) ranged from 77 to 148 mg kg-1.
STP was higher in mixed forest stand than in monoculture and decreased
with soil depth. The TPo and labile-P in both soil layers increased
significantly with increase in age of oak trees. In addition,
TPo content was lower in mineral soil compared to the forest floor
and accounted for more than 50％ of soil total P in the forest
stands. The most available-P fraction-labile-P predominated in
the oldest pine-oak forest stand (P + O124), accounting for 29％
of STP at the 0-10 cm soil depth. The largest P fraction comprised
NaOH-Po and represent 62％ of STP. Results showed that forest transformation
from pure pine monoculture forest into pine-oak mixed forest stands
promoted an increase in the TPo and P available. Furthermore,
the forms of labile available P increased with age of oak trees,
which are capable of maintaining larger fractions of available
P under mixed forest stands.
Keywords: Sequential P extraction; P availability; Forest management;
Pinus sylvestris; Quercus petraea』
1. Introduction
2. Materials and methods
2.1. Site description
2.2. Sampling
2.3. Chemical analyses
2.4. Microbial analysis
2.5. Soil organic P fractionation
2.6. Statistical analysis
3. Results
3.1. General soil properties
3.2. Forest floor
3.3. Sequential organic P fractionation
3.4. Relationship among soil properties and Po fractions
4. Discussion
4.1. General soil properties
4.2. Forest floor
4.3. Sequential organic P fractionation
4.4. Relationship among soil properties and Po fractions
5. Conclusion
Acknowledgements
References
※土壌リンの連続抽出這法は、Bowman and Cole（1978）の方法をSharpley and Smith（1985）とIvanoff et al.（1998）が修正したものを用いている。