Responses in gross primary production of Stipa krylovii and Allium polyrhizum to a temporal rainfall in a temperate grassland of Inner Mongolia, China

In the arid and semi-arid areas of China, rainfall and drought affect the growth and photosynthetic activities of plants.Gross primary productivity(GPP) is one of the most important indices that measure the photosynthetic ability of plants.This paper focused on the GPP of two representative grassland species(Stipa krylovii Roshev.and Allium polyrhizum Turcz.ex Regel) to demonstrate the effect of a temporal rainfall on the two species.Our research was conducted in a temperate grassland in New Barag Right Banner, Hulun Buir City, Inner Mongolia Autonomous Region of China, in a dry year 2015.We measured net ecosystem productivity(NEP) and ecosystem respiration flux(ER) using a transparent chamber system and monitored the photosynthetically active radiation(PAR), air and soil temperature and humidity simultaneously.Based on the measured values of NEP and ER, we calculated the GPP of the two species before and after the rainfall.The saturated GPP per aboveground biomass(GPPAGB) of A.polyrhizum remarkably increased from 0.033(±0.018) to 0.185(±0.055) μmol CO2/(gdw·s) by 5.6-fold and that of S.krylovii decreased from 0.068(±0.021) to 0.034(±0.011) μmol CO2/(gdw·s) by 0.5-fold on the 1st and 2nd d after a 9.1 mm rainfall event compared to the values before the rainfall at low temperatures below 35℃.However, on the 1st and 2nd d after the rainfall, both of the saturated GPPAGB values of S.krylovii and A.polyrhizum were significantly lower at high temperatures above 35℃(0.018(±0.007) and 0.110(±0.061) μmol CO2/(gdw·s), respectively) than at low temperatures below 35℃(0.034(±0.011) and 0.185(±0.055) μmol CO2/(gdw·s), respectively).The results showed that the GPP responses to the temporal rainfall differed between S.krylovii and A.polyrhizum and strongly negative influenced by temperature.The temporal rainfall seems to be more effective on the GPP of A.polyrhizum than S.krylovii.These differences might be related to the different physiological and structural features, the coexistence of the species and their species-specific survival strategies.

未来气候条件下蒙古草原植被的预测分布

蒙古牧民家庭通过适应当地植被分布的特点来维持牲畜的健康状况。因此,预测未来植被变化对于稳定的牲畜放牧和可持续的草原利用至关重要。本研究基于前期研究获得的植被数据预测了2081年至2100年间草原植被,尤其是沙漠草原、草原和草甸草原的分布范围。我们首先基于在蒙古(43–50°N,87–119°E)收集的草原植被数据(2012至2016年,278个样地)划分了不同的群落类型。其次,采用最大熵(MaxEnt)模型进行物种分布建模,其中以荒漠草原、草原和草甸草原的分布数据作为目标变量,使用WorldClim的生物气候数据作为解释变量。最后,采用WorldClim提供的CMIP6下缩放的未来气候预测数据进行未来预测。结果发现,荒漠草原、草原和草甸草原模型的曲线下面积值分别为0.850、0.847和0.873。根据所有情景和所有群落的气候变化,适宜栖息地预计将缩小。潜在适宜区域减少的程度在草甸草原群落中最为显著。上述结果表明,未来气候变化情景下草甸草原群落将转变为草原群落。

蒙古牧场植物群落的组成、分布和环境驱动因素

在蒙古,过度放牧和由此导致的牧场退化仍是比较严重的问题。为解决牧场退化问题,我们试图以区域特征对蒙古牧场群落进行广泛的植被分类;此外,我们试图阐明群落的空间分布和分布的环境驱动因素。在2012-2016年,我们调查了蒙古不同地区的278个地块(10 m×10 m)的植被,这些地块的放牧压力相对于邻近地区较低。使用改进的双向指示物种分析方法(TWINSPAN),将数据分组为植被单元。然后,我们探讨了物种组成和群落分布的区域特征,以及分布与气候变量之间的关系。改进的TWINSPAN将植被数据分为3个集群,每个集群对应一种特定类型的带状植被(即森林草原、草原和沙漠草原)。干旱指数被确定为所有集群分布的重要驱动因素,而经度和海拔是集群组内集群分布的重要决定因素。与东部地区相比,西部地区具有更高的海拔和大陆性特征,在最潮湿的季度平均气温和降水量较低,导致集群组内的物种组成存在差异。物种组成的区域差异反映了植物地理起源的差异。因此,蒙古牧场群落的物种组成和分布模式框架与气候和地理因素相关。