镇海棘螈产卵场微生境选择

Spawning ground microhabitat selection by the Chinhai spiny newt(Echinotriton chinhaiensis)

镇海棘螈(Echinotriton chinhaiensis)为国家一级重点保护野生动物,其种群面临着生境退化及丧失的重要威胁。产卵是决定镇海棘螈种群数量增长的关键环节之一,了解其产卵选择的微生境偏好可以更有针对性地保护该物种。本研究旨在确定影响镇海棘螈产卵场微生境选择的关键环境变量,同时为该物种的产卵生境保护、改造和重建提供科学基础。本文于2021年3-5月(繁殖期)在浙江省宁波市北仑区林场对镇海棘螈产卵位点(n=105)与非产卵位点(n=70)处的18个微生境变量进行调查。采用拟合优度卡方检验判断3种无序分类变量的差异性,并利用生境喜好系数对生境选择性进行分析。采用二元逻辑斯蒂回归模型对15个数值型变量进行分析,确定影响镇海棘螈产卵微生境选择的关键变量。结果显示镇海棘螈繁殖期间对产卵场微生境有明显偏好,通常产卵于朝向水坑、落叶层较厚(5.19±0.18 cm)、坡度较陡(18.64°±1.18°)和土壤含水量较低(33.51%±1.87%)的土壤基质上。此外,在大型遮蔽物中,镇海棘螈偏好选择体积较小的石块和乔木(2,994.63±316.17 cm^(3))作为遮蔽且离遮蔽物较近(54.27±3.84 cm)的生境产卵。直接的遮蔽物——落叶层和大型遮蔽物(石块和乔木)的体积均在镇海棘螈产卵选择上起着最重要的作用,其次为到最近大型遮蔽物的距离。镇海棘螈在选择产卵微生境时,需要同时兼顾遮蔽物特性、水源条件、微气候环境等多个方面的需求,遮蔽条件是决定镇海棘螈产卵场选择的关键因子。建议对产卵场周边落叶阔叶林进行重点保护。

Aim:The Chinhai spiny newt(Echinotriton chinhaiensis)has received a first-class National Protected Wildlife status in China.Its population is under severe threats such as habitat degradation and habitat loss.Spawning is crucial for the population growth of E.chinhaiensis.Therefore,understanding the preference of spawning sites can be crucial for protection and integrated management of the Chinhai spiny newt and its spawning ground.In this paper,we carried the study to identify the main environmental variables that affected the selection of spawning ground microhabitat of E.chinhaiensis,and to provide baseline data for spawning ground protection,transformation and reconstruction.Methods:From March to May 2021,we investigated 18 microhabitat variables of spawning sites(n=105)and non-spawning sites(n=70)of E.chinhaiensis at the Forest Farm of Beilun District,Ningbo City,Zhejiang Province during its breeding period.Goodness of fit test was utilized to analyze the differences between 3 disordered categorical variables,and the habitat preference index was used to analyze the habitat selection.To examine patterns in microhabitat selection of E.chinhaiensis,we used Binary Logistic Regression Model to analyze 15 numerical variables.Results:The results indicated that,generally,E.chinhaiensis preferred to spawn on steep terrain with soil tilting towards the puddles(18.64°±1.18°),deeper leaf litter(5.19±0.18 cm),less soil water content(33.51%±1.87%).In addition,eggs of E.chinhaiensis were often spawned near small rocks or trees(54.27±3.84 cm in a distance),which provided shelter(2,994.63±316.17 cm^(3)in volume).Leaf litter depth and volume of large shelter(rocks or trees)were both the most important in determining the spawning microhabitat of E.chinhaiensis,secondary importance was distance to nearest large shelter.Conclusions:E.chinhaiensis selected microhabitat for spawning that simultaneously meet the requirements of shelter characteristics(leaf litter depth,large shelter tape,volume of large shelter,distance from large shelter),water feature(spawning site aspect,slope),microclimate(soil water content,substrate type).Variables related to shelter are important characteristics for choosing the microhabitat by E.chinhaiensis.For effective species conservation,we recommend protection of deciduous broad-leaved forest around spawning ground.