基于日光诱导叶绿素荧光探测植被光合对气象干旱的响应     

齐晓雯  苗晨  王鹤松 《中国农业气象》2023,44(2):133-143

干旱是世界范围内最常见、最复杂的气象灾害,一定程度上会削弱陆地生态系统的碳汇功能。开展植被对干旱响应的研究并选择敏感的干旱探测因子,有助于掌握干旱对植被的影响规律、理解植被对干旱胁迫的响应过程和机理。本研究以日光诱导叶绿素荧光（SIF）数据和标准化降水蒸散发指数（SPEI）为基础,利用最大相关系数法分析中国区域内2000-2018年生长季植被光合对气象干旱的响应,比较不同干旱梯度、不同植被对干旱响应的敏感性以及SPEI响应时间尺度的变化特征。结果表明：（1）SIF与SPEI具有很好的相关性,显著正相关的面积达到75.05%,主要分布在东北、西南和青藏高原地区,且大部分地区对SPEI的响应时间尺度以中短期为主。（2）SIF在春季对SPEI显著相关的区域占比最少,夏季达到最高,秋季又略有下降。对干旱响应的时间尺度在春季以短期为主,而夏季响应时间尺度长的区域较春季有所增加。（3）半干旱区对干旱的敏感性最强,干旱区最弱,不同气候区对干旱的响应时间尺度均以短期为主。（4）研究所选植被类型均能较早地对干旱做出响应,其中,草地对干旱最敏感,林地和农田相对较弱,阔叶林比针叶林对干旱更敏感。研究结果表明...  相似文献   

Hydrus-2D模拟起垄覆膜处理对夏玉米生育期水量平衡的影响     

付玉娟  李尧  喻浩洋  吴佳钰  张旭东 《农业工程学报》2023,39(10):76-87

为探究起垄和覆膜处理对辽西北半干旱区夏玉米生育期水量平衡的影响,该研究在建平县节水灌溉试验站将田间试验与Hydrus-2D模拟相结合,探究各典型年夏玉米生育期水量平衡的变化规律。结果表明：Hydrus-2D模型能够有效地对起垄和覆膜处理后夏玉米生育期的下垫面降雨入渗过程进行模拟,各下垫面实测值与模拟值的R²均不小于0.87,均方根误差均小于0.01 cm³/cm³;覆膜后各典型年的蒸发量平均减少52.24 mm,蒸腾量平均增加31.84 mm;覆膜会抑制多日持续降雨期间的深层渗漏速率,促进单日超过40 mm降雨的雨后深层渗漏速率;覆膜能减少作物生育期的农田耗水量（蒸发量,蒸腾量和深层渗漏量之和）,使各典型年的平均农田耗水量减少25.74 mm,增加覆膜垄作处理的覆膜宽度能够进一步减少作物生育期的农田耗水量。因此,在辽西北半干旱区进行起垄和覆膜对缓解该地区的农业缺水紧张情势,丰富农田生育期水分转化结构的相关理论具有重要作用。  相似文献   

Variations in annual precipitation and selenium accumulation by Milk‐Vetch     

U. M. Cowgill 《Journal of plant nutrition》2013,36(1):73-80

Four Se accumulators and two non‐accumulator plants were examined for their Se content in wet and dry years. No significant change in Se quantity was noted in the non‐accumulators in relation to variations in annual precipitation. However, the concentration of Se found in accumulator plants is significantly higher in wet years than in dry ones. Furthermore, in wet years there is a higher percentage of water soluble Se in these plants than in dry ones. The soils supporting these plants were also examined for their Se content. In dry years these soils contain more water soluble Se than in wet ones but, in dry years, this form of Se is less available due to the lack of available moisture. High precipitation may tend to reduce absorption of Se by plants by diluting the water soluble Se present in the soil solution, but it is clear that it also promotes absorption of Se by encouraging vigorous growth of these accumulator plants.  相似文献   

Interrelationship among slope steepness,tillage practice and rainfall properties with surface runoff and soil loss on Mollisols in Northeast China     

Shuai Chen  C. Lee Burras  Lili E 《Archives of Agronomy and Soil Science》2013,59(13):1860-1872

ABSTRACT

Soil erosion and rainfall-induced runoff are well studied yet remain somewhat unpredictable from one natural rainfall to the next, due to interactions between erosion parameters. This study quantified the relationship between annual (2011–2016) and individual (2016) rain events with overland flow (runoff) and soil loss in China’s northern ‘corn-belt’. Two tillage practices and slopes were evaluated (no-till and conventional till, 5° and 7° slopes). Results showed 54 rainfall events for a total of 394 mm precipitation ranging between May and October 2016. Runoff occurred 13 times in the conventional till with 7° slope, accounting for 25.9% of the precipitation volume and caused 15.6 t ha^?1 erosion. It occurred twice in the no-till with 5° slope plot and caused 0.2 t ha^?1 erosion., Thus the no-till with 5° slope treatment is the best tillage system to protect soil in Mollisols in Northeast China. Broad analysis coupled with a detail review of three rainfall events demonstrates that water either runs off plots quickly or rapidly infiltrates while sediment moves in a pulsing manner.  相似文献   

The decomposition of turfgrass clippings is fast at high air humidity and moderate temperature     

Karin Kauer  Henn Raave  Tiina Köster  Rein Viiralt  Merrit Noormets  Indrek Keres 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):224-234

Abstract

In grassland areas where herbage production has no economic value, the cut grass is often left on the sward surface where its decomposition is influenced by weather conditions. Although the influence of temperature and humidity on decomposition has been investigated under controlled lab conditions, experimentation has generally been under ideal moisture conditions that have not tested the combinations of climatic limitations that might occur in the field. The decomposition of mown turfgrass clippings deposited at different times of vegetation period was studied in situ using nylon bags during the first 8 weeks after deposition to investigate the effect of weather conditions (the air temperature, relative humidity, precipitation) on decomposition. Decomposition is the highest in the case of high air humidity and temperature of 10°C. Limiting factors for decomposition at temperatures above 10°C is the air humidity and below 10°C the air temperature. The general tendency was that the rate of decomposition increased with increasing air temperature up to 10°C, but with further increases of air temperature the decomposition rate slowed down. Relative air humidity had a variable impact (at the beginning of the decomposition process (weeks 1–2) the influence was negative, during weeks 3–8 of the decomposition process the effect was positive), and hence had no generalized relationship with decomposition over the studied decomposition period (weeks 1–8). The most significant influence of weather conditions on the decomposition rate was recorded directly after cutting. If the cutting was done during hot weather conditions, the material was drying fast and therefore decomposed slowly. Our results indicate that for fast decomposition of clippings it is important to maintain the freshness of material. Lower decomposition rates occurred during conditions of hot and dry weather, and also cooler (temperature near to 0°C) weather, and can be compensated as soon as favourable weather arrives.  相似文献   

Effect of long-term intensive rice cultivation on the available silica content of sawah soils: Java Island,Indonesia     

《Soil Science and Plant Nutrition》2013,59(6):745-753

Abstract

The dramatic increases in rice productivity and cultivation intensity through the implementation of green revolution (GR) technology using high yielding varieties (HYVs) of rice and chemical fertilizers were not long lasting in Indonesia. The stagnancy of rice productivity in recent years without any scientific reasons presents a challenge for agronomists and soil scientists in Indonesia. This study describes the effects of long-term intensive rice cultivation on the change in available silica (Si) in sawah soil. The term sawah refers to a leveled and bounded rice field with an inlet and an outlet for irrigation and drainage. Soil samples collected by Kawaguchi and Kyuma in 1970 and new samples taken in 2003 from the same sites or sites close to the 1970 sites were analyzed and compared. From 1970 to 2003, the average content of available Si decreased from 1,512 ± 634 kg SiO₂ ha^?1 to 1,230 ± 556 kg SiO₂ ha^?1 and from 6,676 ± 3,569 kg SiO₂ ha^?1 to 5,894 ± 3,372 kg SiO₂ ha^?1 in the 0–20 cm and 0–100 cm soil layers, respectively. Cultivation intensity differences between seedfarms planted with rice three times a year and non-seedfarms rotating rice and upland crops appeared to affect the changing rates of available Si within the study period. In the 0–20 cm soil layer, the average content of available Si decreased from 1,646 ± 581 kg SiO₂ ha^?1 to 1,283 ± 533 kg SiO₂ ha^?1 (?22%) and from 1,440 ± 645 kg SiO₂ ha^?1 to 1,202 ± 563 kg SiO₂ ha^?1 (?17%) in seedfarms and non-seedfarms, respectively. Differences in topographical position also influenced the decreasing rate of available Si in this study. Using similar management practices and cultivation intensity, upland sampling sites lost more Si compared with lowland sites. Planted rice under a rain fed system with no Si addition from rain water in an upland position may be a reason for the higher loss of Si, particularly in non-seedfarms. The Si supply from irrigation water might have contributed to the slowdown in the decreasing rate of available Si in Java sawah soils.  相似文献   

ASSESSING LAND DEGRADATION RISK THROUGH THE LONG‐TERM ANALYSIS OF EROSIVITY: A CASE STUDY IN SOUTHERN SPAIN     

E. V. Taguas  E. Carpintero  J. L. Ayuso 《Land Degradation \u0026amp; Development》2013,24(2):179-187

Despite the high variability of the precipitation regime characterizing the Mediterranean area, the records of rainfall depth are usually not appropriate for long‐term calculations of erosivity and soil losses, because they do not reveal details of short lengths or long durations (daily, monthly). In this work, we present a simple approach to calculate annual erosivity through monthly precipitation records. The study area (olive groves on steep slopes) has a high erosion risk associated to the main soil land use, combined with an irregular and erosive rainfall regime. The relationships between rainfall data at intervals of 10 min for a period of 3 years, daily rainfall records over 10 years and a long‐term monthly dataset of 60 years were checked to calculate the annual erosivity values through daily data, Fourier's index and modified Fourier's index values. A good, adjusted linear relationship between modified Fourier's index and the erosivity was found, which allowed us to optimize the use of the 60‐year monthly data series and to carry out a long‐term analysis of the erosivity quantiles in the study area. The estimated mean erosivity showed a return period of between 2 and 5 years and a variation coefficient of over 50 per cent, which illustrate its high variability and frequency. This approach to calculate erosivity and the use of quantiles could be applied in other areas with month‐long data series in order to study and model the erosion risk using suitable temporal periods. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

基于标准化降水指数的河南省近45年干旱时空特征分析     

商东耀  张志红  岳元  胡程达  王琪 《干旱地区农业研究》2021,39(4):162-170

依据河南省45个气象站近45年逐月降水资料,以标准化降水指数作为干旱指标,详细分析河南省范围内干旱强度、影响范围、发生频率的时空演变规律。结果表明:(1)在过去45 a中河南省干旱具有明显的周期性且近年来有增强的趋势;从干旱发生站次比上来看,年尺度干旱站次比呈阶段性先增后减的变化趋势,且在全省范围内多发全域性、局域性干旱,分别为11、12 a;春季、夏季、秋季三季干旱站次比呈现上升趋势,上升率分别为1%·10a~(-1)、5.5%·10a~(-1)、9.6%·10a~(-1),其中,夏旱多为区域性干旱,春、秋两季多为全域性干旱,分别为13、12 a。(2)全省平均干旱频率为9.83%,秋季干旱频率高于其他三个季节,为17.53%;河南省东部商丘地区、西部三门峡地区是年、季尺度干旱高发地区,年尺度干旱强度与干旱站次比在时间上变化规律一致,都存在2～6 a的周期性。(3)年尺度干旱强度呈现增强趋势,20世纪90年代干旱强度最高,不同季节中干旱强度都表现为增强的趋势,为此河南省未来发生全域性干旱的风险依然很高。  相似文献   

Response of hydrological drought to meteorological drought in the eastern Mediterranean Basin of Turkey     

Türkan BAYER ALTIN 《干旱区科学》2021,13(5):470-486

The hydrographic eastern Mediterranean Basin of Turkey is a drought sensitive area. The basin is an important agricultural area and it is necessary to determine the extent of extreme regional climatic changes as they occur in this basin. Pearson's correlation coefficient was used to show the correlation between standardized precipitation index(SPI) and standardized streamflow index(SSI) values on different time scales. Data from five meteorological stations and seven stream gauging stations in four sub-basins of the eastern Mediterranean Basin were analyzed over the period from 1967 to 2017. The correlation between SSI and SPI indicated that in response to meteorological drought, hydrological drought experiences a one-year delay then occurs in the following year. This is more evident at all stations from the mid-1990 s. The main factor causing hydrological drought is prolonged low precipitation or the presence of a particularly dry year. Results showed that over a long period(12 months), hydrological drought is longer and more severe in the upper part than the lower part of the sub-basins. According to SPI-12 values, an uninterrupted drought period is observed from 2002–2003 to 2008–2009. Results indicated that among the drought events, moderate drought is the most common on all timescales in all sub-basins during the past 51 years. Long-term dry periods with moderate and severe droughts are observed for up to 10 years or more since the late 1990 s, especially in the upper part of the sub-basins. As precipitation increases in late autumn and early winter, the stream flow also increases and thus the highest and most positive correlation values(0.26–0.54) are found in January. Correlation values(ranging between –0.11 and –0.01) are weaker and negative in summer and autumn due to low rainfall. This is more evident at all stations in September. The relation between hydrological and meteorological droughts is more evident, with the correlation values above 0.50 on longer timescales(12-and 24-months). The results presented in this study allow an understanding of the characteristics of drought events and are instructive for overcoming drought. This will facilitate the development of strategies for the appropriate management of water resources in the eastern Mediterranean Basin, which has a high agricultural potential.  相似文献   

Assessing the response of dryland barley yield to climate variability in semi-arid regions,Iran     

Mohammad KHEIRI 《干旱区科学》2021,13(9):905-917

Precipitation and temperature are the most abiotic factors that greatly impact the yield of crop, particularly in dryland. Barley, as the main cereal is predominantly cultivated in dryland and the livelihood of smallholders depends on the production of this crop, particularly in arid and semi-arid regions. This study aimed to investigate the response of the grain yield of dryland barley to temperature and precipitation variations at annual, seasonal and monthly scales in seven counties of East and West Azerbaijan provinces in northwestern Iran during 1991-2010. Humidity index (HI) was calculated and its relationship with dryland barley yield was evaluated at annual and monthly scales. The results showed that the minimum, maximum and mean temperatures increased by 0.19°C/a, 0.11°C/a and 0.10°C/a, respectively, while annual precipitation decreased by 0.80 mm/a during 1991-2010. Climate in study area has become drier by 0.22/a in annual HI during the study period. Negative effects of increasing temperature on the grain yield of dryland barley were more severe than the positive effects of increasing precipitation. Besides, weather variations in April and May were related more to the grain yield of dryland barley than those in other months. The grain yield of dryland barley was more drastically affected by the variation of annual minimum temperature comparing with other weather variables. Furthermore, our findings illustrated that the grain yield of dryland barley increased by 0.01 t/hm² for each unit increase in annual HI during 1991-2010. Finally, any increase in the monthly HI led to crop yield improvement in the study area, particularly in the drier counties, i.e., Myaneh, Tabriz and Khoy in Iran.  相似文献