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15 March 2019, Volume 36 Issue 2 Previous Issue    Next Issue

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Cover 2019, 36 (2):  0-0.  Abstract ( 537 )   PDF (272KB) ( 105 )   Related Articles | Metrics

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Contents 2019, 36 (2):  0-0.  Abstract ( 209 )   PDF (315KB) ( 105 )   Related Articles | Metrics

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Change and Attribution of Reference Evapotranspiration over the Tibetan Plateau during the Period of 1971-2014 WANG Bu wei, ZHANG Xue qin 2019, 36 (2):  269-279.  Abstract ( 2219 )   PDF (5212KB) ( 281 )   It is indispensable to explore the spatiotemporal variation of reference evapotranspiration over the Tibetan Plateau and its driving factors so as to deepen the understanding of regional hydrological process and its response to climate change. The daily data from 75 meteorological stations over the plateau were utilized to analyze the spatiotemporal change of evapotranspiration based on the modified formula of FAO 56 Penman-Monteith, and the contribution of climatic factors to the variation during the period of 1971-2014 was discussed. The main conclusions are summarized as follows: Annual reference evapotranspiration over the Tibetan Plateau tended to an increase, especially in the region south from 33°N from 1997 to 2014 with an average linear trend of 40.16 mm·(10a)-1. It, however, decreased remarkably at the rate of -27.07 mm·(10a)-1 from 1971 to 1996, and the dominant climatic factor resulting in the decrease was the reduction of wind speed, especially in Northern Plateau. Reduction of relative humidity played a crucial role in increasing the reference evapotranspiration from 1997 to 2014. In addition, the biggest contribution factor to the seasonal variation of reference evapotranspiration shifted from the reduction of wind speed (from 1971 to 1996) to the decrease of relative humidity (from 1997 to 2014) and the dominant factor to the summer variation of reference evapotranspiration shifted from the increase of relative humidity (from 1971 to 1996) to the increase of annual mean relative sunshine duration (from 1997 to 2014). References | Related Articles | Metrics

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Soil Nitrogen Mineralization under Pinus sylvestris var. mongolica Plantation on Sandy Soil KONG Tao, ZHANG Ying, LEI Ze yong, WANG Dong li, LIU Yang, YU Ji, WU Dan 2019, 36 (2):  296-306.  Abstract ( 442 )   PDF (1781KB) ( 429 )   The availability of soil nitrogen (N) is a key limiting factor for the productivity and stability of sandy forest ecosystems. In this study, the changes of NH4+-N、NO3--N and mineral N contents and the ammoniation, nitrification and nitrogen mineralization rates of soil under the Pinus sylvestris var. mongolica plantations with 10-60year stand ages were determined. The results showed that the NH4+-N、NO3--N and mineral N contents of soil under the P.sylvestris plantations were increased with the increase of forest stand age in a range of 10-60 years, in which the increase under the plantations with 10-30year stand ages was low, and it was significantly improved under the plantations with 40-60 year stand ages. Soil NH4+-N、NO3--N and mineral N contents were decreased with the increase of soil depth, and they were distributed mainly in 0-20 cm soil layers. The soil ammoniation, nitrification and mineralization rates under the plantations were increased with the increase of forest stand age, and these indexes of the 0-40 cm soil layer was obviously higher than those of 40-100 cm soil layer. The two factor analysis of variance revealed that the effects of forest stand age and soil layer on the mineralization indexes were significant. Soil mineralization indexes had a significant positive correlation with plant height, diameter at breast height, crown width and the contents of soil organic carbon, total nitrogen and alkali nitrogen in the plantations. The redundancy analysis showed that the main environmental factors affecting soil mineralization indexes under the plantations with different stand ages were total nitrogen, total phosphorus and soil organic carbon; the main environmental factors affecting mineralization indexes of different soil layers were alkali hydrolyzable nitrogen, total phosphorus and soil organic carbon. Therefore, the P.sylvestris plantation could be used to improve the soil N in sandy land, the improvement effect of young and middle aged plantations on soil N was small, and that of nearmature forest and mature forest was obvious. The improvement effect of plantation on topsoil was better than that of deep soil. Soil fertility was the main environmental factor affecting soil mineralization index. References | Related Articles | Metrics

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Soil Water and Salt Migration in Cotton Field in Ridge Furrow Planting andConventional Flat Planting under Drip Irrigation SUN Chi-tao, ZHANG Jun-peng, ZHANG Qian, FENG Di, FENG Guo-yi, SUN Jing-sheng, LIN Yong-zeng 2019, 36 (2):  307-313.  Abstract ( 3198 )   PDF (1371KB) ( 508 )   In this study, two typical cotton planting ways, i.e. the ridge furrow planting and conventional flat planting, were selected in the coastal area with severe soil salinization so as to clarify the effect of different cotton transplanting ways on soil water and salt migration under drip irrigation. The soil moisture content, soil salinity and soil solution conductivity at different sites and depths were investigated before and after drip irrigation. Spatial and temporal distribution characteristics of soil moisture content, soil salinity and soil solution conductivity were analyzed. The result showed that the depth of soil water infiltration and salt leaching in ridge furrow treatment was deeper than that of conventional flat planting treatment, and the soil solution concentration in 0-20 cm soil layer in ridge furrow planting pattern was lower than that of conventional flat planting treatment. There was no significant difference in soil water and salt migration outside the plastic film mulch under the two treatments. The combined drip irrigation technology in ridge furrow planting was more conducive to providing a suitable water and salt environment for cotton growth. This study could provide both theoretical and practical references for cotton cultivation in saline soil. References | Related Articles | Metrics

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Effects of Straw Turnover on Soil WaterStable Aggregates and Soil Carbon Distribution WANG Meijia, WANG Feng, SU Sihui, SU Yehan, SUN Yue, WANG Yingyan, MENG GuangXin, JIANG Ying, QI Hua 2019, 36 (2):  331-338.  doi: 10.13866/j.azr.2019.02.08 Abstract ( 325 )   PDF (1137KB) ( 239 )   In this study,the effects of crop residue turnover on the composition and stability of soil water-stable agglomeration and the distribution of soil organic carbon in aggregates were investigated for giving a reference to crop production and crop residue turnover in the semiarid areas in northeast China. A field experiment including rotary tillage and plough tillage with/without crop residue incorporation treatments (RT,CK1,PT and CK2) was started in 2015. The purposes of this study were to explore the effects of tillage and straw management practices on the ratio of soil aggregates with various sizes,stability of soil waterstable agglomeration,distribution of soil organic carbon (SOC) in 2017 and maize yield from 2015 to 2017. Our results indicated that the residue incorporation could be used to significantly increase the SOC content by 13.90% (RT) and 9.29% (PT),respectively,in 0-10 cm soil layer compared with those without residue incorporation(P<0.05).Compared with PT,the content of water-stable aggregates (>2 mm) and average weight diameter of aggregates (MWD) were significantly increased by 22.05% and 7.78%,respectively,while the content of water-stable aggregates (<0.053 mm) was significantly decreased by 16.81% by RT management (P<0.05).In addition,RT significantly enhanced the SOC of water-stable aggregates in topsoil,and the most improvement was found in the water-stable aggregates>2 mm (P<0.05). There was no significant difference in maize yield in 2016 and 2017. Compared with the yield in 2016,the yield reduction from RT and PT treatments (8.57%-9.72%) was lower than that from CK1 and CK2 (10.84%-12.13%) in 2017. Therefore,the rotary tillage with residue returning practice in dryland farming is recommended with benefits of promoting soil water-stable aggregate formation and increasing SOC content so that give a stable yield for maize production regardless of precipitation variation in northeast China. Related Articles | Metrics

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Effects of NAO on the Extreme Cold Events in Xinjiang in Winter 2019, 36 (2):  348-355.  Abstract ( 535 )   PDF (3398KB) ( 295 )   The frequency and circulation of extreme cold events in Xinjiang in winter were analyzed based on the daily air temperature data from the meteorological stations in Xinjiang,NCEP reanalysis data of the height field,wind field,temperature field and North Atlantic Oscillation (NAO) index during the period of 1961-2016. The variation of extreme cold events in Xinjiang in winter was affected by the Eurasia (EU) wave train transmission,in winter,however,there was no one to one corresponding negative correlation between the NAO phase and the extreme cold events in Xinjiang in winter. In the winter of NAO negative phase,NAO was spread by the EU wave train,and the north wind was weak in north of 70°N. Under this background,the extreme cold events in Xinjiang in winter were more (less) when the geopotential height over the Ural Mountain and its east region was high (low) and the west wind was weak (strong) in 50°-70°N. In the winter of NAO positive phase,NAO was spread by the EU wave train,and the north wind was strong in north of 70°N. Under this background,the extreme cold events in Xinjiang in winter were more (less) when the geopotential height over the Ural Mountain and its east region was high (low) and the west wind was weak (strong) in 50°-70°N. The result showed that the occurrence frequency of extreme cold events in Xinjiang was mainly affected by the interaction of NAO,the geopotential height field over the Ural Mountain and its east region and the west wind in 50°-70°N,of which,the west wind in 50°-70°N in winter and the geopotential height field over the Ural Mountain and its east region were the main affecting factors. References | Related Articles | Metrics

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Photosynthetic Traits of Caragana microphylla and Populus spp. and Their Responses to Climate in the Horqin Sandy Land BAO Yong-zhi, LIU Ting-xi, DUAN Li-min, WANG Guan-li, QI Xiu-jiao, HUANG Tian-Yu, LI Ming-Yang 2019, 36 (2):  420-429.  Abstract ( 435 )   PDF (1KB) ( 527 )   In this paper, the photosynthetic traits of Caragana microphylla and Populus spp. were measured with LI-6400 in field. The adaptability of C.microphylla and Populus spp. and their response to drought and precipitation were lucubrated after comparing and analyzing the differences in photosynthetic traits of these two plant species and the relationship between their physiological characteristics and environmental factors under drought and after precipitation. The results are as follows: ① Under drought, the net photosynthetic rate (Pn), transpiration rate (Tr) and the stomatal conductance (Gs) of the two mixed growing plants were decreased significantly, showing a significant “midday depression”, and the peak value occurred earlier. The “midday depression” of C.microphylla was disappeared after precipitation; ② Pn values of C.microphylla and Populus spp. were mainly affected by physiological factor (Gs) and environmental factor photosynthetically active radiation (PAR). The photosynthetic traits of C.microphylla was mainly affected by stomatal regulation (Gs) under drought, and it was mainly affected by environmental factors (PAR) after precipitation. The photosynthetic traits of Populus spp. were relatively stable under both drought and after precipitation, and they were mainly affected by environmental factors (PAR); ③ To adapt drought environment, C.microphylla maintained a low Tr and a high water use efficiency (WUE), while Populus spp. adapted drought by high Pn and Tr and low WUE. After precipitation, the change of photosynthetic traits of C.microphylla was more significant than that of Populus spp. and the former was more sensitive to precipitation than the latter. In mixed community of C.microphylla and Populus spp., the adaptability of the two plant species to precipitation was significantly different, and C.microphylla had a higher adaptability to environment changes. References | Related Articles | Metrics

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Response of Stoichiometric Characteristics of Nitrogen and Phosphorus in Plant Leaves in an Alpine Grasslands to Nitrogen Deposition in the Tianshan Mountains SU Yuan, LUO Yan, GENG Feng zhan, HAN Wen xuan, ZHU Yu mei, LI Kai hui, LIU Xue jun 2019, 36 (2):  430-436.  Abstract ( 473 )   PDF (1KB) ( 364 )   Atmospheric nitrogen (N) deposition is rapidly increased due to the increase of human activities and climate change, which enhances the N availability and affects the nutrient cycling of plants in alpine grasslands. However, there is still much debate about how the change of nutrient availability affects P content in plants, therefore, the effects of N addition on N and P contents and N∶P stoichiometry in mature and senesced leaves at plant organ level in the Bayinbuluk alpine grasslands in the northwest Tianshanin Mountains in China were examined based on a 10-year field experiment. The nitrogen and phosphorus contents in mature and senesced leaves of Potentilla bifurca, Leymus tianschanicus and Koeleria cristata were measured, and the values of foliar stoichiometry under N addition treatments at levels of 0,3,9 g·m-2·a-1) were estimated. Results showed that there were the significant differences of the values of nutrient concentration and foliar stoichiometry between the mature and senesced leaves. The N contents in mature and senesced leaves were 12.78 mg·g-1 and 6.88 mg·g-1,and the P contents were 0.88 mg·g-1 and 0.46 mg·g-1, respectively. N and P concentrations in mature and senesced leaves were in an order of P.bifurca > L.tiansecalinus > K.cristata. After the N treatments for 10 years, the N contents in mature and senesced leaves were increased by 12% and 48% respectively. It was found that there was a divergent response of P content in leaves, the effect of N addition on foliar P content was different from different plant species, and the P content in senesced leaves was decreased by N addition. N∶P in senesced leaves was increased significantly but not in mature leaves. In addition, the correlations between N and P elements and plant stoichiometry in mature and senesced leaves were different. There was a positive correlation between foliar N and P contents of P.bifurca in mature leaves (P<0.05), but a negative correlation in senesced leaves. Our finds revealed that nitrogen addition affected significantly the nutrient content and stoichiometry in leaves of the three species, but there was a significant difference among species. The increase of N deposition would affect the nutrient cycling of plants in grasslands in the Tianshan Mountains. References | Related Articles | Metrics

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Species Diversity and Co-Occurrence Pattern at Patch Scale in Stipa breviflora Desert Steppe YU Rui-xin, TIAN Na, WANG Xing, WANG Lei, YANG Xin-guo, JIANG Qi, ZHOU Juan 2019, 36 (2):  444-450.  Abstract ( 510 )   PDF (1KB) ( 152 )   Clarifying the species co-occurrence pattern at patch scale is of important significance for understanding the maintenance mechanism of biodiversity in desert steppe fragmentation. According to the degree of soil habitat degradation at patch scale, this study contrasted and examined the species composition and diversity of different patches and the species co-occurrence pattern based on three typical patches in a Stipa breviflora desert steppe. The results indicated that ① Patch A was a consociation and belonged to a community of S. breviflora. Patch B was a community of S. breviflora and Astragalus melilotoides. And Patch C was a community of Sophora alopecuroides + Cynanchum komarovii + Artemisia scoparia).   ② In community structure, the diversity of Patch A and Patch B was similar and higher than that of Patch C where S. breviflora grew.  ③ The analyzed results based on the null model showed that the complexity and intensity of species co-occurrence patterns was in an order of Patch A > Patch B > Patch C. Four of the 16 significant species pairs in patch A had a significant competitive relation, while the species pairs in patch C were reduced to 7 groups, and there was only one significant competitive species pair (A. scoparia and S. alopecuroides) in patch C. Therefore, Non-desertified soil habitat patches were the important prerequisite for the biodiversity maintenance of desert steppe fragmentation. The non-desertified of soil habitat reduced significantly the complexity of community structure within patches and the intensity of interaction between species, which was unconducive to the self-maintenance of the community. References | Related Articles | Metrics

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Dynamic State of Desert Vegetation Productivity and Its Relationship with Water-Heat Factors in China LIU Xue-jia, DONG Lu, ZHAO Jie, DU Zi-qiang, ZHANG Hong 2019, 36 (2):  459-466.  Abstract ( 518 )   PDF (1KB) ( 438 )   In this paper, the CASA (Carnegie-Ames-Stanford Approach) model was used to estimate the NPP of desert vegetation in its growing season from 1982 to 2015, and the linear regression and GIS spatial analysis methods were applied to analyze the spatiotemporal variation of NPP. The purposes of the study were to explore the net primary productivity of desert vegetation and its correlation with water-heat factors in China’s arid regions in recent three decades. The sliding correlation coefficient was used to analyze the relationship between NPP and water-heat factors. The results showed that:   ① The average NPP per unit area was 42 g·m-2·a-1, and the overall level of NPP was low. Spatially, it was higher in the northwestern and eastern margins but lower in the central, southern and mid-eastern regions;  ② The average annual NPP of desert vegetation was 5.78×1013 g·a-1. For the interannual variation, the linear change rate of the total NPP of desert vegetation was 1.64×1012 g·(10a)-1 (P=0.054) in China from 1982 to 2015, desert vegetation was generally improved, but the total change trend was staged. The total amount of NPP showed an extremely significant growth trend (1.25×1012 g·a-1, P<0.01) during the period of 1982-1993, it was significantly decreased from 1993 to 2006 (-0.64×1012 g·a-1, P<0.01), and increased slowly during the period of 2006-2015 (0.17×1012 g·a-1, P>0.05). From the perspective of spatial change, 47.65% NPP of desert vegetation was in an increase trend, which was mainly distributed in the Alashan Plateau, north piedmont of the Tianshan Mountains, western marginal zone of the Tarim Basin, southeastern marginal zone of the Qaidam Basin, south piedmont of the Altun Mountains, and Kunlun Mountains;  ③ From the perspective of the change of correlation between desert vegetation NPP and climatic factors with the time, the sliding correlation coefficient between NPP and temperature was negatively correlated with the time, but positively correlated between NPP and precipitation and dryness. There was no significant variation of sliding correlation coefficient between NPP and total solar radiation with the time. In general, the correlation between desert vegetation and water-heat factors was further weakened during the study period, that is, the desert vegetation NPP was increasingly insensitive to the change of climatic factors.  References | Related Articles | Metrics

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Spatiotemporal Differentiation of Ecosystem Services in the Shiyang River Basin from 2005 to 2015 WANG Bei, ZHAO Jun, ZHONG Jun-tao 2019, 36 (2):  474-485.  Abstract ( 761 )   PDF (3414KB) ( 261 )   The study on ecosystem services has become as a hot topic and frontier in the field of ecology. The Shiyang River Basin was taken as the research object to estimate the ecosystem services including the water conservation, soil retention, water purification, biodiversity sustaining, carbon storage and food supply based on GIS technology and methods in 2005, 2010 and 2015. Moreover, the evolution of the spatiotemporal pattern of ecosystem services, change of ecosystem services based on land use types and compartment of ecosystem functions were explored and studied. The results firstly showed that:  ① these ecosystem services presented the spatially differential characteristics, the spatial pattern of water conservation, biodiversity maintenance and carbon storage presented the characteristics that the “lowvalue zones were located in the northeast, and the highvalue zones were mostly distributed in the southwest”. In addition, the distribution of highvalue zones of water purification was fragmentary. And the highvalue zones of food supply were located in Wuwei, Yongchang and Minqin basins; ② Among the different land use types, grassland and cultivated land played the main role of providing ecosystem services; ③ The basin was divided into three ecological functional areas, namely Qilian ecological conservation area, watershed oasis ecological function area and desert ecological function area. The study and analysis of the spatiotemporal differentiation of ecosystem services in the Shiyang River Basin provided the support of data and methods for relevant research, and also the scientific references for determining the goal of watershed ecological protection and construction. References | Related Articles | Metrics