The unique regional climate characteristics are among the main reasons for the frequent wind-sand activity in arid and cold areas in the agro-pastoral ecotone in Inner Mongolia, China. This paper focuses on the time s...The unique regional climate characteristics are among the main reasons for the frequent wind-sand activity in arid and cold areas in the agro-pastoral ecotone in Inner Mongolia, China. This paper focuses on the time series of temperature and precipitation in spring when sandstorms often occur in the area. Based on meteorological data for a 46-year period from 1959 to 2004, multi-scale variations and abrupt changes in temperature and precipitation were analyzed with the Mexican hat function （MHF） wavelet method, showing the multi-scale variation characteristics of temperature and precipitation, as well as the periods and change points at different time scales. The relationship between temperature and precipitation was obtained using the wavelet analysis method. Obvious staggered features of the variations of spring temperature and precipitation were observed in this agro-pastoral ecotone. The strongest oscillation periods of spring temperature variations were 1 and 22 years, while for precipitation, the strongest oscillation periods of variations were 2, 8, and 22 years. In addition, lower spring temperature corresponded to lower precipitation, whereas higher temperature yielded higher precipitation rate.展开更多
The aboveground primary production is a major source of carbon(C) and nitrogen(N) pool and plays an important role in regulating the response of ecosystem and nutrient cycling to natural and anthropogenic disturbances...The aboveground primary production is a major source of carbon(C) and nitrogen(N) pool and plays an important role in regulating the response of ecosystem and nutrient cycling to natural and anthropogenic disturbances. To explore the mechanisms underlying the effect of spring fire and topography on the aboveground biomass(AGB) and the soil C and N pool, we conducted a field experiment between April 2014 and August 2016 in a semi-arid grassland of northern China to examine the effects of slope and spring fire, and their potential interactions on the AGB and organic C and total N contents in different plant functional groups(C_3 grasses, C_4 grasses, forbs, Artemisia frigida plants, total grasses and total plants).The dynamics of AGB and the contents of organic C and N in the plants were examined in the burned and unburned plots on different slope positions(upper and lower). There were differences in the total AGB of all plants between the two slope positions. The AGB of grasses was higher on the lower slope than on the upper slope in July. On the lower slope, spring fire marginally or significantly increased the AGB of C_3 grasses, forbs, total grasses and total plants in June and August, but decreased the AGB of C_4 grasses and A.frigida plants from June to August. On the upper slope, however, spring fire significantly increased the AGB of forbs in June, the AGB of C_3 grasses and total grasses in July, and the AGB of forbs and C_4 grasses in August. Spring fire exhibited no significant effect on the total AGB of all plants on the lower and upper slopes in 2014 and 2015. In 2016, the total AGB in the burned plots showed a decreasing trend after fire burning compared with the unburned plots. The different plant functional groups had different responses to slope positions in terms of organic C and N contents in the plants. The lower and upper slopes differed with respect to the organic C and N contents of C_3 grasses, C_4 grasses, total grasses, forbs, A. frigida plants and total plants in different growing months. Slope position and spring fire significantly interacted to affect the AGB and organic C and N contents of C_4 grasses and A. frigida plants. We observed the AGB and organic C and N contents in the plants in a temporal synchronized pattern. Spring fire affected the functional AGB on different slope positions, likely by altering the organic C and N contents and, therefore,it is an important process for C and N cycling in the semi-arid natural grasslands. The findings of this study would facilitate the simulation of ecosystem C and N cycling in the semi-arid grasslands in northern China.展开更多
气候变化背景下,为探索黄土高原半干旱区春玉米光合生理过程对土壤水分、温度变化的响应机制,以春玉米为研究对象,于2017年在中国气象局定西干旱气象与生态环境试验基地进行盆栽水分控制试验,在春玉米七叶期设置对照处理(Control,简称...气候变化背景下,为探索黄土高原半干旱区春玉米光合生理过程对土壤水分、温度变化的响应机制,以春玉米为研究对象,于2017年在中国气象局定西干旱气象与生态环境试验基地进行盆栽水分控制试验,在春玉米七叶期设置对照处理(Control,简称“CK处理”,土壤水分为田间持水量的80%)和控水处理(Water Stress,简称“WS处理”,土壤水分为田间持水量的45%~50%)以及3个叶片温度梯度,分别为适宜温度25℃、高温35℃及极端高温40℃(CK处理对应CK-25、CK-35及CK-40;WS处理对应WS-25、WS-35及WS-40),分析春玉米叶片气体交换参数和水分利用效率对土壤水分、温度变化的响应特征。结果表明:在一定的光合有效辐射(Photosynthetically Active Radiation,PAR)范围内,春玉米叶片净光合速率(Net Photosynthetic Rate,Pn)随PAR的增加逐渐增大。水分供给不足时,随着PAR不断增加,WS处理春玉米叶片气孔限制因素向非气孔限制因素转变,光合作用出现明显的光抑制,WS-35处理叶片Pn最大,WS处理叶片Pn在PAR高值区明显小于CK处理,且不同温度梯度下叶片达到光饱和的PAR下降;与CK-40处理相比,WS-40处理春玉米叶片Pn随PAR增大显著减小(P<0.05),光合作用表现出明显的光抑制。水分供给充足时,蒸腾速率(Transpiration Rate,Tr)随温度升高而增大;水分供给不足时,WS-40处理春玉米叶片Tr、气孔限制(Ls)较CK-40处理显著降低(P<0.05),胞间CO_(2)浓度(Ci)显著增加(P<0.05)。WS-40处理春玉米Tr随着PAR的增大而减小,水分利用效率(Water Use Efficiency,WUE)较CK处理高。该研究可为气候变化背景下黄土高原半干旱区春玉米应对极端气候生理特征变化提供参考。展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 100262001)the Advanced University Science Foundation of Inner Mongolia (Grant No. NJzy08044)the Ph. D. Foundation of Inner Mongolia Agricultural University (Grant No. BJ07-27)
文摘The unique regional climate characteristics are among the main reasons for the frequent wind-sand activity in arid and cold areas in the agro-pastoral ecotone in Inner Mongolia, China. This paper focuses on the time series of temperature and precipitation in spring when sandstorms often occur in the area. Based on meteorological data for a 46-year period from 1959 to 2004, multi-scale variations and abrupt changes in temperature and precipitation were analyzed with the Mexican hat function （MHF） wavelet method, showing the multi-scale variation characteristics of temperature and precipitation, as well as the periods and change points at different time scales. The relationship between temperature and precipitation was obtained using the wavelet analysis method. Obvious staggered features of the variations of spring temperature and precipitation were observed in this agro-pastoral ecotone. The strongest oscillation periods of spring temperature variations were 1 and 22 years, while for precipitation, the strongest oscillation periods of variations were 2, 8, and 22 years. In addition, lower spring temperature corresponded to lower precipitation, whereas higher temperature yielded higher precipitation rate.
基金supported by the National Key Basic Research and Development Program of China (2016YFC0500703)the National Natural Science Foundation of China (31572452, 41573063, 31870438)
文摘The aboveground primary production is a major source of carbon(C) and nitrogen(N) pool and plays an important role in regulating the response of ecosystem and nutrient cycling to natural and anthropogenic disturbances. To explore the mechanisms underlying the effect of spring fire and topography on the aboveground biomass(AGB) and the soil C and N pool, we conducted a field experiment between April 2014 and August 2016 in a semi-arid grassland of northern China to examine the effects of slope and spring fire, and their potential interactions on the AGB and organic C and total N contents in different plant functional groups(C_3 grasses, C_4 grasses, forbs, Artemisia frigida plants, total grasses and total plants).The dynamics of AGB and the contents of organic C and N in the plants were examined in the burned and unburned plots on different slope positions(upper and lower). There were differences in the total AGB of all plants between the two slope positions. The AGB of grasses was higher on the lower slope than on the upper slope in July. On the lower slope, spring fire marginally or significantly increased the AGB of C_3 grasses, forbs, total grasses and total plants in June and August, but decreased the AGB of C_4 grasses and A.frigida plants from June to August. On the upper slope, however, spring fire significantly increased the AGB of forbs in June, the AGB of C_3 grasses and total grasses in July, and the AGB of forbs and C_4 grasses in August. Spring fire exhibited no significant effect on the total AGB of all plants on the lower and upper slopes in 2014 and 2015. In 2016, the total AGB in the burned plots showed a decreasing trend after fire burning compared with the unburned plots. The different plant functional groups had different responses to slope positions in terms of organic C and N contents in the plants. The lower and upper slopes differed with respect to the organic C and N contents of C_3 grasses, C_4 grasses, total grasses, forbs, A. frigida plants and total plants in different growing months. Slope position and spring fire significantly interacted to affect the AGB and organic C and N contents of C_4 grasses and A. frigida plants. We observed the AGB and organic C and N contents in the plants in a temporal synchronized pattern. Spring fire affected the functional AGB on different slope positions, likely by altering the organic C and N contents and, therefore,it is an important process for C and N cycling in the semi-arid natural grasslands. The findings of this study would facilitate the simulation of ecosystem C and N cycling in the semi-arid grasslands in northern China.
文摘气候变化背景下,为探索黄土高原半干旱区春玉米光合生理过程对土壤水分、温度变化的响应机制,以春玉米为研究对象,于2017年在中国气象局定西干旱气象与生态环境试验基地进行盆栽水分控制试验,在春玉米七叶期设置对照处理(Control,简称“CK处理”,土壤水分为田间持水量的80%)和控水处理(Water Stress,简称“WS处理”,土壤水分为田间持水量的45%~50%)以及3个叶片温度梯度,分别为适宜温度25℃、高温35℃及极端高温40℃(CK处理对应CK-25、CK-35及CK-40;WS处理对应WS-25、WS-35及WS-40),分析春玉米叶片气体交换参数和水分利用效率对土壤水分、温度变化的响应特征。结果表明:在一定的光合有效辐射(Photosynthetically Active Radiation,PAR)范围内,春玉米叶片净光合速率(Net Photosynthetic Rate,Pn)随PAR的增加逐渐增大。水分供给不足时,随着PAR不断增加,WS处理春玉米叶片气孔限制因素向非气孔限制因素转变,光合作用出现明显的光抑制,WS-35处理叶片Pn最大,WS处理叶片Pn在PAR高值区明显小于CK处理,且不同温度梯度下叶片达到光饱和的PAR下降;与CK-40处理相比,WS-40处理春玉米叶片Pn随PAR增大显著减小(P<0.05),光合作用表现出明显的光抑制。水分供给充足时,蒸腾速率(Transpiration Rate,Tr)随温度升高而增大;水分供给不足时,WS-40处理春玉米叶片Tr、气孔限制(Ls)较CK-40处理显著降低(P<0.05),胞间CO_(2)浓度(Ci)显著增加(P<0.05)。WS-40处理春玉米Tr随着PAR的增大而减小,水分利用效率(Water Use Efficiency,WUE)较CK处理高。该研究可为气候变化背景下黄土高原半干旱区春玉米应对极端气候生理特征变化提供参考。
