| Wildfire has both positive and negative effects on the process of forest ecosystem succession.Research on the ecological effects of wildfires on wildlife is becoming critically important for humanity because the number of large and intense fires is increasing with climate change.The impact of wildfire on an ecosystem should be analyzed as an ecological process,where the assessment depends on specific spatio-temporal scales.As an indicator group of ecological environment,birds are an important indicator of habitat service function.However,there is still a lack of research on the impact of wildfire on bird diversity in China.Northwest Yunnan is one of the most fire-prone regions in China,and it is also one of the regions with the richest bird diversity.Pinus yunnanensis forest is the main vegetation type in this region,and it is a fire-dependent ecosystem.Research on the impact of wildfire on bird diversity is important for avian conservation and effective forest management in this type of ecosystem.A forest fire occurred in February 2013 at Dafengba,Dali,southwest China.One month after the fire,an assessment of fire severity and its impacts on avian communities has been performed,providing an initial blueprint for discussing the changes of bird diversity in the years after the fire.Therefore,based on this data,we conducted a new survey in situ to evaluate the long-term effects of different fire severities on the overall diversity of birds as well as on each functional guild.The following two scientific questions were explored:（1）How different fire severity affect the diversity of the bird communities and do these effects change with time?（2）How different fire severity affect the diversity of different functional guilds.To ensure compatibility among studies,we adopted the same bird survey design and methods.At 8th breeding season for birds after the fire,we performed repeated bird counts in 198 sample points,set up with a fixed radius of 80m,distributed within land patches burned at different severity according to the burn severity index:unburned area（control area）,low severity,moderate severity,and high severity area.The effects of different fire severity on bird diversity were analyzed at the landscape and patch scale usingα,βandγdiversity metrics for avian diversity.The results demonstrate that:（1）The effects of wildfire on bird diversity depend on the specific spatial-temporal scale.The burned areas hold significantly higherγdiversity of birds than the unburned areas,but opposite forαdiversity in both the 1stand the 8thyear after fire.Bird diversity significantly decreased in the high severity areas as compared to the unburned areas in the both periods.However,there was a tendency to recovery in the high severity areas,showing a significantly higher avian diversity at the8thyear than the 1styear after the fire.Moreover,similarities of the avian composition among different fire severities were higher in the 8ththan the 1styear after fire.（2）The wildfire could significantly increase the diversity of the larger,granivores,and ground nesters,and significantly decrease the diversity of omnivores,nectarivores,insectivores,shrub nesters,open-cup nesters,and cavity nesters.However,these effects weakened with time.Conclusion:The effects of wildfire on bird diversity in a Pinus yunnanensis forest depend on spatio-temporal scales.The effects of different fire severity on diversities of all birds and different functional guilds were various.Avian diversity in burned areas had a tendency to recover to the level of unburned areas with the succession of vegetation after fire.High severity burning could significantly decrease avian diversity and this negative impact could last for long periods than other relatively light severities.In order to avoid the occurrence of high severity burning and promote the improvement of regional biodiversity,it is recommended to carry out planned burning to reduce the fuel load. |
