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1.
Plant productivity and nitrogen gas fluxes in a tallgrass prairie landscape   总被引：2，自引：1，他引：1  
We explored relationships between plant productivity and annual fluxes of nitrogen (N2) and nitrous oxide (N2O) in a tallgrass prairie landscape in central Kansas. Our objective was to develop predictive relationships between these variables that could be used in conjunction with remote sensing information on plant productivity to produce large-area estimates of N gas fluxes. Our hypothesis was that there are inherent relationships between plant productivity and N gas fluxes in tallgrass prairie because both are controlled by water and N availability. The research was carried out as part of a multi-investigator project, the First ISLSCP Field Experiment (FIFE, ISLSCP = International Satellite Land Surface Climatology Program), directed toward the use of remote sensing to characterize land-atmosphere interactions. Fluxes of N2 (denitrification) and N2O were measured using soil core techniques. Estimates of annual flux were produced by temporal extrapolation of measured rates. Annual aboveground net primary productivity (ANPP) was estimated from measurements of the maximum standing crop of plant biomass. There were strong relationships between ANPP and N gas fluxes, and between a satellite remote sensing-based index of plant productivity (normalized difference vegetation index, NDVI) and gas fluxes. We used these relationships to convert images of NDVI into images of N gas fluxes for one 83 ha watershed and for the entire 15 by 15 km FIFE site. These images were used to compute mean landscape gas fluxes (0.62 g N m-2 y-1 for N2, 0.66 g N m-2 y-1 for N2O) and total N gas production for the two areas. Our flux and production values are useful for comparison with values produced by simulation models and site-specific studies, and for assessing the significance of N gas production to ecosystem and landscape scale processes related to nutrient cycling, water quality and atmospheric chemistry.  相似文献   

2.
Subtropical forest loss resulting from conversion of forest to other land-cover types such as grassland, secondary forest, subsistence crop farms and small forest patches affects leaf nitrogen (N) stocks in the landscape. This study explores the utility of new remote sensing tools to model the spatial distribution of leaf N concentration in a forested landscape undergoing deforestation in KwaZulu-Natal, South Africa. Leaf N was mapped using models developed from RapidEye imagery; a relatively new space-borne multispectral sensor. RapidEye consists of five spectral bands in the visible to near infra-red (NIR) and has a spatial resolution of 5 m. MERIS terrestrial chlorophyll index derived from the RapidEye explained 50 % of the variance in leaf N across different land-cover types with a model standard error of prediction of 29 % (i.e. of the observed mean leaf N) when assessed on an independent test data. The results showed that indigenous forest fragmentation leads to significant losses in leaf N as most of the land-cover types (e.g. grasslands and subsistence farmlands) resulting from forest degradation showed lower leaf N when compared to the original indigenous forest. Further analysis of the spatial variation of leaf N revealed an autocorrelation distance of about 50 m for leaf N in the fragmented landscape, a scale corresponding to the average dimension of subsistence fields (2,781 m2) in the region. The availability of new multispectral sensors such as RapidEye thus, moves remote sensing closer to widespread monitoring of the effect of tropical forest degradation on leaf N distribution.  相似文献   

3.
We applied drone remote sensing to identify relationships between key forest health indicators collected in the field and four Vegetative Indices (VI) to improve conservation management of urban forests. Key indicators of urban forest health revealed several areas of conservation concern including a majority of overstory trees in moderate to severe decline, canopy gaps, anthropogenic dumping, vines overtaking the forest canopy, and invasion by non-native plant species. We found plot-level vegetation index (VI) values of NDVI, NDRE, GNDVI, and GRVI calculated from drone imagery are significantly related to the impact of several of these ecological concerns as well as metrics of forest composition and equitability. Despite the small number of plots, too few to provide a general predictive framework, these findings indicate a substantial potential for drone remote sensing as a low-cost, efficient tool for urban forest management. We discuss how our findings can advance urban forest management and discuss challenges and opportunities for future drone VI research in urban natural areas.  相似文献   

4.
Alleviating salinity stress by modifying the physiology of the medicinal plant globe artichoke (Cynara scolymus L.) was investigated in a field experiment using salicylic acid (SA). The objectives were to determine: (1) the physiological response of artichoke under salinity stress, and (2) whether SA can alleviate the adverse effects of salinity by affecting artichoke physiology. The factorial combination of salty water (control, 8 dS/m, and 14 dS/m) and foliar application of SA (control, 0.1, 1 mM) was tested. A 1500-L tank was used in the field to establish the favorable salinity levels. Salinity increased chlorophyll a and total chlorophyll; however, at the medium level of SA, chlorophyll a decreased. Increasing salinity and SA decreased total phenolic contents. Increased salinity increased plant proline and ionic leakage. Interestingly, SA significantly decreased ionic leakage, compared with the control. SA increased proline production at different levels of salinity. SA at 0.1 mM was the most suitable and effective treatment under salinity stress. It is possible to alleviate the stress of salinity on artichoke growth by modifying plant physiology using the appropriate concentration of SA.  相似文献   

5.
Field sampling and satellite remote sensing were used to test the hypothesis that site microclimate variability leading to divergent soil water use by vegetation types is closely associated with variability in annual net primary productivity (NPP) at the landscape scale. A simulation model based on satellite observations of seasonal phenology was used to estimate NPP of grassland, shrubland, and conifer forest vegetation types on the Central California coast near Big Sur. Daily microclimate at the soil surface was monitored over 4 years (2008–2011) for each vegetation type to infer soil moisture controls on plant production. Grassland soils were found to have lower soil organic matter content and were subjected to extreme radiation and wind events, and thereby dry-down faster with daily spring–summer warming than do shrubland or redwood forest soils. This reduced moisture microclimate affected the water stress on grassland plants to reduce NPP fluxes from April to October each year on the Central Coast far sooner than for shrubland or redwood stands. Results from this study suggested that the satellite-observed canopy greenness variations represented can be used to quantify plant production in coastal ecosystems at the landscape scale of defined microclimate variation.  相似文献   

6.
以松花菜品种"力禾65天"为试材,采用重力滴灌灌溉方式,设置微咸水灌水梯度3g·L-1(3K)、5g·L-1(5K),以淡水(CK)为对照,研究不同浓度微咸水胁迫对松花菜生长指标、品质及水分利用效率的影响,以期为设施农业中微咸水资源安全利用提供技术支撑。结果表明:在松花菜生长指标方面,随着灌溉水矿化度的升高,苗期松花菜死苗率增大,营养生长末期(莲座期末期)叶片数和花球直径显著降低,5K处理莲座期末叶片数比CK降低34.78%,花球直径比CK降低32.34%;在产量方面,随着灌溉水矿化度含量的升高,松花菜的产量显著下降,5K处理单株产量比CK降低48.31%;在品质方面,可溶性糖、可溶性蛋白质以及维生素C含量随着灌溉水矿化度含量的升高呈现先增加后降低的变化趋势,排序依次为可溶性糖含量3K>5K>CK,维生素C含量3K>5K>CK,可溶性蛋白质含量3K>CK>5K;叶片叶绿素含量和水分利用效率随着灌溉水矿化度含量的升高而降低,变化规律为CK>3K>5K。  相似文献   

7.
负水头供不同营养液对温室樱桃番茄生长和产量的影响   总被引：2，自引：0，他引：2  
采用负水头灌溉装置,通过调节装置的供水吸力值来持续稳定地控制栽培基质的湿度,供给不同浓度磷酸二氢钾（KH2PO4）营养液配方进行樱桃番茄基质栽培试验,研究营养液中不同磷酸二氢钾浓度对樱桃番茄株高、茎粗、产量、水肥利用效率和根系活力的影响。结果表明：在负水头供水控水技术条件下,适当提高营养液中磷酸二氢钾浓度,有利于增加樱桃番茄株高、茎粗,效果显著;同时可以提高果实产量、水分利用效率和N、K利用效率以及根系活力。负水头供给营养液樱桃番茄栽培生产中,2.5 S处理即340 mg•L-1的KH2PO4浓度可作为推荐用量。  相似文献   

8.
The purpose of this study was to analyze the physiological and morphological response of carnation plants to different levels of irrigation and to evaluate regulated deficit irrigation as a possible technique for saving water through the application of controlled drought stress. Carnations, Dianthus caryophyllus L. cultivar, were pot-grown in an unheated greenhouse and submitted to two experiments. In the first experiment, the plants were exposed to three irrigation treatments: (control); 70% of the control (moderate deficit irrigation, MDI) and 35% of the control (severe deficit irrigation, SDI). In the second experiment, the plants were submitted to a control treatment, deficit irrigation (DI, 50% of the control) and regulated deficit irrigation (RDI). After 15 weeks, MDI plants showed a slightly reduced total dry weight, plant height and leaf area, while SDI had clearly reduced all the plant size parameters. RDI plants had similar leaf area and total dry weight to the control treatment during the blooming phase. MDI did not affect the number of flowers and no great differences in the colour parameters were observed. RDI plants had higher flower dry weight, while plant quality was affected by the SDI (lower number of shoots and flowers, lower relative chlorophyll content). Leaf osmotic potential decreased with deficit irrigation, but more markedly in SDI, which induced higher values of leaf pressure. Stomatal conductance (gs) decreased in drought conditions more than the photosynthetic rate (Pn). Osmotic adjustment of 0.3 MPa accompanied by decreases in elasticity in response to drought resulted in turgor less at lower leaf water potentials and prevented turgor loss during drought periods.  相似文献   

9.
In dryland areas, secondarily treated municipal wastewater could be used in extensive green roof systems. In this study, the effects of water and salt stress on a crassulacean acid metabolism (CAM) plant, Sedum kamtschaticum Fischer, was evaluated under intermittent saline irrigation. The salinity of irrigation water varied from 6.0 to 18.0 dS m?1. A reduction in soil water content and an increase in soil water electrical conductivity (EC) were observed during the irrigation interval (5–17 d) as a result of evapotranspiration (ET). The effect of soil water potential (SWP) on reduction of the ET ratio (ETr) was successfully described with an equation that could be applicable to a wide range of soil salinities and water contents, to estimate ET. In this study, the stress factor was defined as the integration of solute potential, and matric potential less soil water content for optimum growth (less than ?0.1 MPa) with elapsed time. The stress factor rapidly reduced total ET in CAM plants but effectively increased water-use efficiency (WUE). Thus, by using CAM plants for green roofs under intermittent saline irrigation, the need for irrigation water is reduced without a considerable loss of plant biomass.  相似文献   

10.
Paclobutrazol (PBZ) is a member of the triazole plant growth inhibitor group that is responsible for inducing tolerance to a number of biotic and abiotic stresses. An experiment was, therefore, conducted to test whether PBZ application at various concentrations (0, 25, 50, or 75 mg L?1) through foliar spray or soil drench would protect pomegranate (Punica granatum) seedlings cv. Robab, subjected to freezing at ?3°C for 7 hours. PBZ improved the growth rate of pomegranate seedlings subjected to freezing stress and increased relative leaf chlorophyll content, chlorophyll fluorescence ratio, relative water content, soluble carbohydrate content, and enzyme activity of ascorbate peroxidase and guaiacol peroxidase compared with the control at the end of experiment. PBZ ameliorated the injury caused by freezing stress by inhibiting increases in proline content and leaf electrolyte leakage, which suggested that PBZ ameliorated the negative effect of freezing stress. The best protection was obtained from plants treated with PBZ at 50 or 75 mg L?1. The most evaluated parameters were not affected by PBZ application method.  相似文献   

11.
Plant biostimulants are an emerging trend of crop management products which can enhance nutrient uptake, plant growth and productivity under various abiotic stresses. The ability of diluted bee-honey extract (DHE) to enhance the tolerance of onion plants to salinity stress has been investigated. Two-season field experiments were consecutively conducted in 2015/16 and 2016/17 to study the effect of 25–50 g/L DHE foliar application on growth, yield, physio-biochemical attributes, and antioxidative defence of two onion cultivars (i.e. GizaRed and Giza-20) grown on a saline soil (EC = 8.81 dS m?1). Results exhibited that DHE significantly increased biomass production, bulb yield and water use efficiency, leaf photosynthetic and pigments contents. Additionally, DHE applicati\on also improves osmoprotectants, membrane stability index (MSI) and relative water content (RWC), and enzymatic and non-enzymatic antioxidants of both onion cultivars in comparison with untreated control plants. In general, both cultivars showed a similar response to the DHE. Results of this study highlighted the potential impact of DHE as a promising plant bio-stimulant for overcoming the harmful effects of soil salinity stress by increasing the activity of plant antioxidative defence systems  相似文献   

12.
为了筛选出黄瓜潮汐式穴盘育苗最适孔穴型式和营养液浓度,以黄瓜品种中农18号为试材,采用两种类型穴盘(常规、侧开口)和3种浓度(×1、×0.5、×0.25)营养液进行潮汐育苗试验,测定了幼苗矿质元素吸收积累量及表观形态指标等。结果表明:随着营养液浓度逐步提高,黄瓜幼苗矿质元素吸收积累量逐渐增加,N、P、K的吸收积累量增幅达102.6%~125.1%,并促进了叶片叶绿素合成和幼苗株高、茎粗、单株叶面积、地上部干鲜质量等表观参数指标优化。此外,常规穴盘育苗效果总体优于侧开口穴盘。最终,以壮苗指数为主要参考指标,筛选出最佳的孔穴型式与营养液浓度组合,即采用常规穴盘并灌溉完全Hoagland营养液。  相似文献   

13.
Modelling nutrient absorption can contribute to the management of hi-tech cultivation systems in greenhouse horticultural production. Nevertheless, previous studies to understand the kinetics of nutrient absorption, rarely take into consideration the accumulation of salt ions in the nutrient solution. In this project we develop and validate an empirical model for sodium uptake concentration in hydroponic rose (Rosa spp. cv. Kardinal) production. Model development and validation was conducted using a series of experiments in both greenhouse and growth chamber conditions. The model framework takes into account plant developmental stage and external sodium concentration. While model calibration data were collected at levels of sodium up to 40 mol m3 NaCl as root environment salt concentration, model validation was carried out at lower ranges.The proposed model not only shows a high predictive capability, but also provides useful output parameters such as electrical conductivity, which is the main parameter currently monitored for managing nutrient solution in greenhouse cultivation. Incorporated as part of a larger DSS, our model can be used to improve nutrient solution management in production regions that do not have economically valid alternatives other than the use of poor quality (saline) irrigation water.  相似文献   

14.
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15.
为更好探索秋冬茬盆栽彩椒栽培技术,昌平区农业技术推广站示范了椰糠盆栽彩椒营养液循环栽培生产模式。采用自动灌溉、合理的水肥配比、回流液回收利用及栽培管理技术,其中栽培技术内容包括品种选择、培育壮苗、定植及管理、授粉、植株调整、病虫害防治等,实现水肥配比合理化,节省人工;肥效较高,水肥循环利用率达90%,节水50%以上;使作物生长健壮、抗病力强,施药次数减少;667 m~2产量达5 570 kg,比传统栽培模式提高20%,社会、经济和生态效益显著。  相似文献   

16.
Thermal infrared (TIR) remote sensing data can provide important measurements of surface energy fluxes and temperatures, which are integral to understanding landscape processes and responses. One example of this is the successful application of TIR remote sensing data to estimate evapotranspiration and soil moisture, where results from a number of studies suggest that satellite-based measurements from TIR remote sensing data can lead to more accurate regional-scale estimates of daily evapotranspiration. With further refinement in analytical techniques and models, the use of TIR data from airborne and satellite sensors could be very useful for parameterizing surface moisture conditions and developing better simulations of landscape energy exchange over a variety of conditions and space and time scales. Thus, TIR remote sensing data can significantly contribute to the observation, measurement, and analysis of energy balance characteristics (i.e., the fluxes and redistribution of thermal energy within and across the land surface) as an implicit and important aspect of landscape dynamics and landscape functioning.The application of TIR remote sensing data in landscape ecological studies has been limited, however, for several fundamental reasons that relate primarily to the perceived difficulty in use and availability of these data by the landscape ecology community, and from the fragmentation of references on TIR remote sensing throughout the scientific literature. It is our purpose here to provide evidence from work that has employed TIR remote sensing for analysis of landscape characteristics to illustrate how these data can provide important data for the improved measurement of landscape energy response and energy flux relationships. We examine the direct or indirect use of TIR remote sensing data to analyze landscape biophysical characteristics, thereby offering some insight on how these data can be used more robustly to further the understanding and modeling of landscape ecological processes.  相似文献   

17.
李德美  李绍华 《园艺学报》2006,33(2):366-369
 以生长势不同的酿酒葡萄品种赤霞珠和梅鹿辄为试材, 采用基于地物光谱特性的遥感技术获得地块内不同生长势(包括新梢长度、新梢日生长速度、单株叶面积、N-Tester指数) 小区的归一化植被指数(NDVI) 间存在显著差异, 并且NDVI与葡萄新梢长度、新梢日生长速度、植株叶面积以及N-Tester指数间具有显著或极显著的相关性。因此, 采用NDVI评价地块内葡萄长势差异性具有应用前景。  相似文献   

18.
冬季干旱胁迫后复水对鼠茅草生理特性的影响   总被引：1，自引：0，他引：1  
本文通过模拟试验研究了冬季干旱胁迫后复水对鼠茅草生理特性的影响,试验设置了干旱胁迫和正常水分处理,采用PVC管基质栽培鼠茅草,冬季干旱胁迫结束后复水采集鼠茅草样品,测定分析了鼠茅草干旱胁迫后复水及对照处理的鼠茅草叶片及根系的生理生化指标。结果表明,干旱胁迫后复水与正常水分处理相比,叶绿素a含量、总叶绿素含量、生物量、各级根长与根表面积显著降低,叶绿素b指标无显著差异。MDA、可溶性蛋白、电解质渗透率指标显著增加,这说明鼠茅草干旱胁迫复水后仍存在一定的胁迫,冬季干旱胁迫后复水对鼠茅草的生长有一定的抑制作用。试验还表明在不具备冬季灌溉条件下,冬季断水60 d后复水对鼠茅草的生长指标有一定的影响,但不危及生命,可适当断水,在开春后应及时灌溉,以提高光合作用,增加生物量。  相似文献   

19.
为了探明菜豆中期与后期生长对CO2加富与亏缺灌溉的生理响应,试验设两个CO2水平:正常大气浓度和倍增CO2浓度,两个灌溉水平:自然灌溉12次和亏缺灌溉6次,研究CO2加富及亏缺灌溉对菜豆生长的影响。结果表明,CO2加富显著提高菜豆生长中期株高与干质量,净光合速率(Pn)与胞间CO2浓度(Ci)分别显著降低15.48%、37.67%,气孔导度(Gs)显著提高95.83%,菜豆生长后期的叶绿素a/b(Chla/b)显著提高12.29%,水分利用效率(WUE)显著提高46.51%,Ci显著降低12.87%。CO2加富显著提高亏缺灌溉下生长中期菜豆的株高与干质量,但显著降低根冠比,显著提高叶绿素含量以及Gs;CO2加富下生长后期的核酮糖-1,5-二磷酸羧化酶(Rubisco)及果糖-1,6-二磷酸酶(FBPase)活性分别显著提高78.05%与88.69%,CO2加富使亏缺灌溉下碳酸酐酶(CA)与FBPase活性分别显著提高83.73%与64.84%。综上所述,CO2加富提高菜豆生长中期对亏缺灌溉的适应性,对生长后期影响作用减小。  相似文献   

20.
The use of NOAA-AVHRR NDVI time series from July 1981 to December 2000 was evaluated for the assessment of the functioning of a wetland macrosystem, the Paraná River Delta. The spatial resolution of the dataset was 8 by 8 km. Spatial and temporal variations in NDVI pattern were analyzed and evidences for El Niño/South Oscillation events identified. We studied five wetland units (WUs) classified on the basis of landscape pattern and dominant hydrologic regime. Spearman rank correlations were performed among the NDVI time series of the different WUs. NDVI time series were correlated with water level in the Paraná River and with records of local rainfall. In order to obtain a synthetic model of NDVI patterns, the autocorrelation functions (ACF) were estimated for each of the WUs. Results indicated that monthly mean NDVI values for all WUs showed a similar annual seasonal pattern, suggesting a control from the plant annual cycle on the NDVI signal. Besides, two general NDVI patterns were identified. The first pattern is represented by WUs under fluvial hydrologic regime. This is subjected to a significative interannual variability associated mainly to ENSO events. The second pattern corresponds to WUs with a very regular NDVI patterns. It includes wetlands which water input corresponds to tides or to rainfall. The ENSO had no significant influence on this pattern. This study suggests that NOAA-AVHRR NDVI long time series might provide valuable information about functioning of the large scale fluvial wetlands like those associated with South America basins.  相似文献   

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