Effects of environmental variables on seedling distribution of rare and endangered Dacrydium pierrei

Abstract

on the seedling-sapling distribution of Dacrydium pierrei to get reference for its adaptive management with the intense extreme climate change.Keywords: Environment; seedling-sapling; soil moisture; PCA; GMM; Dacrydium pierrei IntroductionClimate changes in China are basically consistent with global warming, the spatial distribution and temporal variation of precipitation variability are large [1], the relative humidity of the ground has decreased in most parts of China [2]. Fog and haze weather, acid rain phenomenon, the shortage of water resources, land desertification and the reduction of forest biodiversity being caused by climate change have become an important topic in the world. The impact of rising temperatures on the environment and ecology is profound [3]. Climate change has a significant impact on the distribution of Chinese plants [4]. Vegetation distribution is determined by their parents distribution as well as by complex environmental factors [5][6]. Seedling-sapling may be the most important stage in the whole life history of plants [7]. Compared with the adult trees, seedlings have stronger sensitivity to the environment [8] Abstract: Because growth environment is affected by climate change, Dacrydium pierrei resources are becoming less and less. Therefore, understanding the effects of environmental variables on seedling-sapling distributions can help gain insight into changes in population recruitment in the context of climate change. The seedlingsaplings distribution and variability of Dacrydium pierrei in environmental variables at Bawangling, Hainan, China, was surveyed over a 3-year period. In addition, laboratory experiments measuring the effects of soil moisture on seedling emergence were conducted to identify seedling development characteristics; principal component analysis (PCA) and Gaussian mixture model (GMM) were used to assess how different factors influenced Dacrydium pierrei seedlings-saplings distribution. The results demonstrated that the influence degree of seedling-sapling distribution is soil temperature>litter thickness>available phosphorus>canopy density> available potassium>nitrate nitrogen; a large number of seedling-saplings occurring at altitudes 1140-1300 m; a GMM trained with a C 2 -L 3 -H 4 -A 5 -I 6 combination yielded an accuracy of 72.23% in simulating seedling-saplings distribution; temperature and precipitation have strong impact on seedling-sapling distribution, with increasing soil moisture, seedling emergence shows a positive relationship. This study focuses more on developing a new method for research