| Amphibian has a very important role in ecosystem. Recently there has been considerable discussion within the scientific community about declines in amphibian densities and distributions in many regions around the world. In ecological engineering, recently, on forest roads that run through mountainous areas, many carcasses of amphibians were often found in the side drainage ditches. So, people wish to improve the design of ditches to make prevention of amphibian mortality in roadside ditch based on not changing the engineering safety.In order to study the theory and technology in building ditch, this research will study roadside ditch in QianKeng Reservoir of ShenZhen. It will discuss the effect to amphibian from roadside ditch based on lots of survey from the below point of view: obliquity of slope surface, material, depth, coverage of vegetation. At last, in order to find the index that Juvenile Toads (Duttaphrynus melanostictus) can endure to the environment, a laboratory simulation will show three aspects about the long jump, the high jump and the angle that juvenile toads can hold on the slope of ditch. The result shows:1. The research of fieldwork shows that there are many kinds of ditches in QianKeng Reservoir, and the depth of most ditches are over 45cm built in concrete or mortar laid stone. There are a few lianas near roadside ditch. These can form a good function of flood prevention and drainage in subtropical monsoon climate, also a traditional design purpose.2. Through visual encounter surveys and transect sampling in the reservoir that is disturbed most severity; it also shows there are seven kinds of amphibians which belongs to one order, four families and five genus, all is anura. However, the number of Juvenile Toads that has the weaker activsity ability is the most suitable species, so we will take it as the experimental material.3. Through out the research, we have found that obliquity of slope surface, material, depth, coverage of vegetation are the main factors that can affect the chance of escaping from a roadside ditch. Our research shows that: (1) the less the depth of roadside ditch are, the easier the juvenile toads can escape from them; (2) the invasion of lianas makes it easier to escaping for our experimental material; (3) among all kinds of ditches that we can find in reservoir, the ditch with an angle of 45 does not make any threaten to toads, a 100% escape rendering; (4) it is better to escape from a slope with mortar laid stone than a slope with concrete.4. Laboratory simulation considering the long jump and the high jump shows that the longer the juvenile toads are, the higher indexes are, until the body length reaches 2.75cm. After that value, the indexes maintain at 11cm and 11.3cm. However, the angle simulation seems the index do not have any relation with the body length, the index is always near 72.8°.This study proves that during the building of roadside ditch, the best depth is no more than 11cm, and for ecosystem, the best angle is 45°, in some cases, it can reach to 78°. Increasing the plant invasion can give the amphibian which lives near the ditches a"natural step". At the same time, it is better to choose mortar laid stone to build the ditch, for it is cheaper than concrete and not easy to breed planus which makes the slope smoother.In the end, when building a ditch, it is very important to consider the need of amphibian. It is a good choice to weaken the effect to livers and create a harmonious environment for both human and nature.
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