分类： 地球科学 >> 地理学 提交时间： 2021-08-06 合作期刊: 《干旱区科学》
摘要： Soil water deficit is increasingly threatening the sustainable vegetation restoration and ecological construction on the Loess Plateau of China due to the climate warming and human activities. To determine the response thresholds of Amygdalus pedunculata (AP) and Salix psammophila (SP) to soil water availability under different textural soils, we measured the changes in net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), leaf water potential (ψw), water use efficiency (WUE) and daily transpiration rate (Td) of the two plant species during soil water content (SWC) decreased from 100% field capacity (FC) to 20% FC in the sandy and loamy soils on the Loess Plateau in the growing season from June to August in 2018. Results showed that Pn, Gs, WUE and Td of AP and SP remained relatively constant at the beginning of soil water deficit but decreased rapidly as plant available soil water content (PASWC) fell below the threshold values in both the sandy and loamy soils. The PASWC thresholds corresponding to Pn, Gs and Ci of AP in the loamy soil (0.61, 0.62 and 0.70, respectively) were lower than those in the sandy soil (0.70, 0.63 and 0.75, respectively), whereas the PASWC thresholds corresponding to Pn, Gs and Ci of SP in the loamy soil (0.63, 0.68 and 0.78, respectively) were higher than those in the sandy soil (0.58, 0.62 and 0.66, respectively). In addition, the PASWC thresholds in relation to Td and WUE of AP (0.60 and 0.58, respectively) and SP (0.62 and 0.60, respectively) in the loamy soil were higher than the corresponding PASWC thresholds of AP (0.58 and 0.52, respectively) and SP (0.55 and 0.56, respectively) in the sandy soil. Furthermore, the PASWC thresholds for the instantaneous gas exchange parameters (e.g., Pn and Gs) at the transient scale were higher than the thresholds for the parameters (e.g., Td) at the daily scale. Our study demonstrates that different plant species and/or different physiological parameters exhibit different thresholds of PASWC and that the thresholds are affected by soil texture. The result can provide guidance for the rational allocation and sustainable management of reforestation species under different soil conditions in the loess regions.
分类： 地球科学 >> 地理学 提交时间： 2020-11-25 合作期刊: 《干旱区科学》
摘要： Amygdalus pedunculata Pall. is a major species that is widely planted in afforested soils with different textures in the transitional zone between Mu Us Desert and Loess Plateau, China. However, the responses of A. pedunculata to increasing intensity of water stress in different textural soils are not clear. Here, we conducted a soil column experiment to evaluate the effects of different textures (sandy and loamy) on water consumption, water use efficiency (WUE), biomass accumulation and ecological adaptability of A. pedunculata under increasing water stress, i.e., 90% (±5%) FC (field capacity), 75% (±5%) FC, 60% (±5%) FC, 45% (±5%) FC and 30% (±5%) FC in 2018. A. pedunculata grown in the sandy soil with the lowest (30% FC) and highest (90% FC) water contents had respectively 21.3%–37.0% and 4.4%–20.4% less transpiration than those with other water treatments (45%–75% FC). In contrast, A. pedunculata transpiration in the loamy soil decreased with decreasing water content. The magnitude of decrease in transpiration increased with increasing level of water deficit (45% and 30% FC). Mean daily and cumulative transpirations of the plant were significantly lower in the sandy soil than in the loamy soil under good water condition (90% FC), but the reverse was noted under water deficit treatments (45% and 30% FC). Plant height, stem diameter and total biomass initially increased with decreasing water content from 90% to 75% FC and then declined under severe water deficit conditions (45% and 30% FC) in the sandy soil. However, these plant parameters decreased with decreasing water content in the loamy soil. WUE in the sandy soil was 7.8%–12.3% higher than that in the loamy soil, which initially increased with decreasing water content from 90% to 75% FC and then declined under water deficit conditions (45% and 30% FC). The study showed that plant transpiration, biomass production and WUE responded differentially to increasing intensity of water stress in the sandy and loamy soils. The contrasting responses of A. pedunculata to water stress in different textural soils can guide future revegetation programs in the northern region of Chinese Loess Plateau by considering plant adaptability to varying soil and water conditions.
分类： 生物学 >> 植物学 >> 应用植物学 提交时间： 2020-05-31 合作期刊: 《干旱区科学》
摘要： Since the Grain for Green (GFG) program was implemented in 1999, most steeply sloping farmlands in the Loess Plateau of China have been returned to forestland and grassland. To understand its impact on the food production, this study analyzed the spatiotemporal changes of food crop production (FCP) in the plateau and quantified the contribution of sown area and yield changes to the total FCP during 1998–2014 using factor decomposition models, and then discussed the impact of GFG program on the FCP based on literature data. With the implementation of GFG program, total sown area in the Loess Plateau quickly deceased by 17.3% from 1998 to 2003, and then gradually restored to 1.03×107 hm2 in 2010. Thereafter, it slightly decreased to 1.02×107 hm2 (94.6% of the area in 1998) in 2014. By contrast, total FCP generally showed an apparent growth trend, averagely increased by 1.71% per year in the whole plateau during 1998–2014. This increase was jointly contributed by the improved yield of individual crops, and the adjustment of cropping structure, i.e., the expansion of high yield maize crop. The factor decomposition analysis results indicate that the sown area shrinkage only reduced the growth rate of total FCP by 0.29% per year during 1998–2014, although a significant impact was found for the early stage of 1999–2003. The results suggest that the implementation of GFG program would not induce an obvious risk of the food security. Therefore, it is suggested that the GFG program should be set as a long-term strategic policy, by not only supporting the conversion of slope farmlands, but also helping local farmers to seek sustainable ways of land use to improve the income and livelihood. It can be combined with the poverty eradication program, to simultaneously achieve the national goals of ecological civilization building and the livelihood improvement of rural people in the Loess Plateau. Considering rainfall limitation, the conversion of slope farmlands should be prioritized to grasslands.
分类： 环境科学技术及资源科学技术 >> 环境科学技术基础学科 提交时间： 2020-04-23 合作期刊: 《干旱区科学》
摘要： Since the Grain for Green (GFG) program was implemented in 1999, most steeply sloping farmlands in the Loess Plateau of China have been returned to forestland and grassland. To understand its impact on the food production, this study analyzed the spatiotemporal changes of food crop production (FCP) in the plateau and quantified the contribution of sown area and yield changes to the total FCP during 1998–2014 using factor decomposition models, and then discussed the impact of GFG program on the FCP based on literature data. With the implementation of GFG program, total sown area in the Loess Plateau quickly deceased by 17.3% from 1998 to 2003, and then gradually restored to 1.03×107 hm2 in 2010. Thereafter, it slightly decreased to 1.02×107 hm2 (94.6% of the area in 1998) in 2014. By contrast, total FCP generally showed an apparent growth trend, averagely increased by 1.71% per year in the whole plateau during 1998–2014. This increase was jointly contributed by the improved yield of individual crops, and the adjustment of cropping structure, i.e., the expansion of high yield maize crop. The factor decomposition analysis results indicate that the sown area shrinkage only reduced the growth rate of total FCP by 0.29% per year during 1998–2014, although a significant impact was found for the early stage of 1999–2003. The results suggest that the implementation of GFG program would not induce an obvious risk of the food security. Therefore, it is suggested that the GFG program should be set as a long-term strategic policy, by not only supporting the conversion of slope farmlands, but also helping local farmers to seek sustainable ways of land use to improve the income and livelihood. It can be combined with the poverty eradication program, to simultaneously achieve the national goals of ecological civilization building and the livelihood improvement of rural people in the Loess Plateau. Considering rainfall limitation, the conversion of slope farmlands should be prioritized to grasslands.
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