Water sources of plants and groundwater in typical ecosystems in the lower reaches of the Heihe River Basin

Stable oxygen and hydrogen isotopic compositions （δ18O and δD） of soil water and shallow groundwater of a riparian forest, an artificial shrub forest, and Gobi of the lower reaches of the Heihe River Basin are used to study the recharge water sources of those ecosystems. IsoSource software is used to determine the δ180 values for root water of Populous euphratica and Tamarix ramosissima in the riparian forest ecosystem, Haloxylon ammodendron in the artificial shrub forest, and Reaumuria soongorica in the Gobi, as well as for local soil water and groundwater, and precipitation in the upper reaches of the Heihe River Basin. Our results showed that soil water and shallow groundwater of the riparian forest and the artificial shrub forest were recharged by river water which originated from precipitation in the upper reaches, and strong evaporation occurred in the artificial shrub forest. Soil water of the Gobi was not affected by Heihe River water due to this area being far away from the river channel. The main water sources of Populous euphratica were from 40-60-cm soil water and groundwater, and of Tamarix ramosissima were from 40-80-cm soil water in the riparian forest ecosystem. In the artificial forest, Haloxylon ammodendron used 200-cm saturated-layer soil water and shallow groundwater. The Reaumuria soongorica mainly used soil water from the 175-200-cm depth in the Gobi. Therefore, soil water and groundwater are the main water sources which maintain survival and growth of the plants in the extremely arid regions of the lower reaches of the Heihe River Basin.

Relationship between the Annual Yield of Black-skinned Sugarcane and Meteorological Disasters in Wengyuan County

The GM(1,1)grey model was used to simulate and divide the harvest years of black-skinned sugarcane yield in Wengyuan County during 2006-2021.Based on the meteorological observation data of Wengyuan County during the same period,the impact of major meteorological disasters such as drought,flood and frost in the growth period of black-skinned sugarcane was analyzed.It is believed that the instability of black-skinned sugarcane yield was affected by comprehensive meteorological factors.It is necessary to master the characteristics of local meteorological disasters,conduct scientific cultivation according to local conditions,and continuously improve the meteorological service level of black-skinned sugarcane cultivation.

Analysis on the Variation Characteristics of Temperature in Wengyuan from 1961 to 2018

Based on the monthly average temperature data from Wengyuan national meteorological observation station in Guangdong Province from 1961 to 2018, statistical methods were used for the trend analysis, mutation detection and wavelet analysis of annual average temperature and seasonal average temperature from 1961 to 2018. The results show that the annual, summer, autumn and winter average temperature in Wengyuan all showed a warming trend from 1961 to 2018, among which winter average temperature contributed the most to the increase of annual average temperature, and the increasing trend of average temperature in spring did not pass the significance test. The annual, summer, autumn and winter average temperature in Wengyuan changed significantly in 1994, 1981, 1996 and 1990, respectively. Wavelet analysis shows that the annual average temperature in Wengyuan had periodic oscillations on the time scales of 12-13, 24-25 and 6 years.

二氧化碳浓度增加和气候变暖导致太白山林线树木生长与氮有效性关系减弱

全球气候变暖、大气二氧化碳浓度(C_(a))升高和氮有效性正对全球森林生态系统产生深远影响,尤其是在高海拔林线地区。本研究结合树木生长指标和树轮稳定同位素指标,探讨了太白山林线树种太白红杉(Larix chinensis)对环境胁迫的生理生态响应。研究结果表明,近60年来太白红杉的生长速度显著增加,且该林线树木生长对春季温度特别敏感。太白红杉的潜在水分利用效率(iWUE)的持续上升与大气二氧化碳浓度升高和气候变暖紧密相关,共同促进了树木的生长。1851-1964年,树轮δ^(15)N随树木生长速度的加快逐渐增大;1964年之后转变为不显著的下降,打破了原有的碳-氮平衡。分析结果表明,自20世纪60年代以来气候变暖和iWUE的迅速增加已经取代氮有效性成为树木生长的主要驱动因子。随着树木持续加速生长,氮有效性在未来可能会显著下降甚至供不应求。本研究深入揭示了植物对生长环境变化响应的生理生态机制,这将提高我们预测未来高海拔地区森林生态系统演变的能力。