Wetland in Napahai Plateau is situated at 99°37′~99°43′E and
27°49′~27°55′N, 3 260 m above sea level. Study area is composed of
meadow, marshes, open water and surrounding forests. 4 kinds of land use types in NapahaiWetlands were selected to study their
soil
nutrient changes under human disturbances. The results of 2-year
studies in the study area showed that the soil organic matter of marsh
meadow, meadow and
cultivated Wetland
in Napahai reduced by 4.33%, 7.32% and 5.64% and their N reduced by
0.1%,0.33% and 0.16% respectively compared to primary marsh. Except for
the content of soil available P and K was higher in cultivated wetland,
other available soil nutrients had the same declining trends as soil
organic matter and total N did. The results also showed that there were
variances of soil enzyme activity from primary marsh to meadow marsh,
meadow and cultivated wetland. In which, the trends of soil Protease
activities and Catalase all were cultivated wetland>primary
marsh>meadow marsh>meadow, of Urease were cultivated
wetland>meadow marsh>primary marsh>meadow, of Polyphenol
oxidase were cultivated wetland>meadow>primary marsh>meadow
marsh, and of Sucrose weer cultivated wetland>primary
marsh>meadow marsh>meadow. In the study, soil organic matter and
total N of cultivated wetland were higher than thoes of meadow and
marsh meadow affecting actually by cultivation and fertilizer
application, which seems good for the soil quality but caused its
wetland functions losing. The soil
degradation index applied to explanation of soil degradation degree indicated that all
utilization types
were degraded and the cultivated wetland was most degradation type
compared to primary marsh. From which it's suggested that cultivated
wetland must convert to wetland so that the aquatic environment of
Napahai can be restored and conserved.
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