Lu Zhongxian, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences (ZAAS), Hangzhou, PR China
Zheng Rongquan, Institute of Ecology, Zhejiang Normal University, Jinhua, PR China
Chen Guihua and Yao Xiaoming, Jinhua Plant Protection Station, Jinhua, PR China
In the ecological engineering fields in Jin Hua, Zhejiang province, flora diversity was enhanced by populating the bunds and non rice habitats with sesame, Zizania and nectar rich flowering plants. This practice has clearly increased the density of parasitoids and predators (Read: Sesame on bunds). In September 2010 a field day organized by the National Agri-tech Extension Service Center (NATESC), Zhejiang Academy of Agriculture Sciences (ZAAS), the Zhejiang Provincial Bureau of Plant Protection and the Jinhua Plant Protection Station (JPPS) attracted national attention (Read: Jinhua gets national attention) .
We also observed substantial increases in frogs, particularly two species Rana limnocharis and R. nigromaculatta. Frogs are known to be excellent indicators of ecosystem health. Amphibians’ thin skins make them susceptible to environmental contaminants, particularly agricultural chemicals. Many insecticides act as endocrine disruptors, inducing feminizing effects and severely affecting populations. Amphibians are like canaries in the coal mine as indicators of toxic gases in the mines, can serve as indicators of polluted environmental conditions which can have severe health consequences. For more details see http://www.amphibianark.org/the-crisis/amphibians-as-indicators/.
Table 1: Mean densities (numbers per mu or 667 m2) of frogs in ecological engineering and farmers’ fields in Jin Hua.
|R. limnocharis||R. nigromaculatta|
|Crop stage||Eco Eng fields||Farmers’ fields||Eco Eng fields||Farmers’ fields|
|Booting||32.67±3.26||6.67±2.81 **||2.20±0.98||0.67±0.67 ns|
|Milky||46.33±6.28||7.35±3.51 **||5.32±2.1||2.01±1.43 ns|
** means are highly significantly different; ns means not significantly different.
As shown in Table 1 and Figure 1, the ecological engineering fields had 4 to 6 times higher frog densities than the farmers fields. The high densities of frogs may have positive effects on pest populations as they are highly effective predators. Further investigations are being carried out in ZAAS to determine its predation effects.
The high densities of frogs are strong indicators of ecosystem health of the ecological engineering fields. The ecological engineering practices of increasing flora biodiversity and reducing insecticide use seem to have encouraged the return of frog and ecosystem health in Jin Hua. Yields of the ecological engineering fields and that of the farmers’ fields were 10.01 t/ha and 10.03 t/ha, respectively.