锡林郭勒草原地上净第一性生产力遥感反演方法初探

探索了利用遥感方法进行牧草消耗量估测，进而进行大面积天然草原地上净第一性生产力估测的方法和技术流程。并以锡林郭勒草原为例，提出了利用MODIS-NDVI反演最高生物量期的牧草采食消耗昔，再利用地面获取的旬度采食系数，推算整个生长季的牧草采食消耗量的思路。在获得草原放牧消耗量基础上，反演了草原净第一性生产力。由于野外测量草原净第一性生产力和消耗量数据的难度较大，所以该方法中的定量分析缺乏对研究区草原净第一性生产力分布特征和消耗量的直接验证，有关反演的方法和可靠性仍有待于进一步验证。     

一种不使用切片机的石蜡制片及其数码照片的光学信息解析

[目的]研究一种不使用切片机的石蜡制片方法,同时提出一种对植物解剖学数码照片进行光学信息解析的方法。[方法]将材料包埋成蜡块,在解剖镜下对材料蜡块进行切片,将切下的薄蜡片卷转移到载玻片上加热,石蜡融化后便将切片展平,再经常规或简化的染色制片程序完成封片。对植物解剖学数码照片处理时,先将其拷入word文档,在文档中获得2份相同的照片,用鼠标选定（刷黑）其中一张,使其成为原照片的＂负片＂,然后复制整个屏幕,将其粘贴到文档中,经剪切等操作后获得处理后的照片。[结果]获得了比较理想的植物解剖学制片。龙爪柳叶片结构的数码照片经过处理后,具有一定的立体感,其角质层和细胞壁等结构及细胞的识别更加容易。[结论]该方法成本低、效率较高,可供初学者或无切片机时使用。对解剖学数码照片进行光学信息解析,能获得普通数码照片无法显示的一些结构信息,显示出光学信息解析的潜力与前景。     

Forty years of lowland monsoon rainforest expansion in Kakadu National Park, Northern Australia

Monsoon rainforest is a key habitat in sustaining the natural and cultural values for which Kakadu National Park is World Heritage listed. The integrity of monsoon rainforest boundaries was thought to have been threatened by an increase in fire and feral animal disturbance over the last few decades. However, as no broad-scale assessment of rainforest boundary change had been undertaken, the rate and even direction of boundary change remained uncertain. In this study changes to the boundaries of 50 monsoon rainforest patches were assessed using temporal sequences of digitised aerial photography, with a view to understanding the relative importance of the drivers of change. Boundaries were compared for each of the years 1964, 1984, 1991 and 2004. Vegetation types were manually classified for each year with a 20 × 20 m point lattice, based primarily on the distance between tree crowns. Transition matrices, size-class distributions and fragmentation indices were calculated. Field samples of a subset of 30 rainforest patches supported the accuracy of the GIS-based mapping of rainforest boundaries. Rainforest patches increased in size between 1964 and 2004 by an average of 28.8%, with an average area increase of 4.0 ha. The expansion is likely to have been primarily driven by increases in variables such as rainfall and atmospheric CO₂, but has been strongly mediated by fire regime. This project has provided land managers with an appreciation of the extent and causes of landscape-scale changes to rainforest boundaries. This will contribute to ‘adaptive management’ programs, especially with respect to fire management.     

Early-stage decomposition of maize litter at different positions in a semi-arid cropland

ABSTRACT

Litter decomposition plays a crucial role in controlling carbon (C) cycling and nutrient turnover in agroecosystems. In this study, the litterbag method was used to investigate the mass loss and nitrogen (N) dynamics of maize litters (culms, leaves and sheaths) at aerial, surficial and belowground positions in the initial 191 d of decomposition. For any tissue, the decomposition rates in the air and on the soil surface were similar, but both were less than the decomposition rates below the ground. The sheaths always decomposed at a lower rate than the other two tissues at any position. During decomposition, the N concentrations for all tissues decreased at both the aerial and the surficial positions but increased for belowground leaves and sheaths in the last months. For the N amount, these three tissues generally exhibited a net N release during the experiment irrespective of the position. Overall, position plays a crucial role in controlling early-stage litter decomposition in croplands, and this role will be modified by litter quality. Therefore, further studies on litter decomposition should fully consider the litter position to comprehensively evaluate the biogeochemical cycles in agroecosystems.     

基于遥感影像研究极端暴雨条件下新成切沟发生发展规律

土壤侵蚀严重破坏土地资源,是全球性的环境问题,切沟侵蚀是土壤侵蚀的重要表现形式,近年来极端暴雨频发加剧了切沟侵蚀的发生和发展。为了研究气候变化条件下新成切沟的形成与发育规律,该研究以陕北子洲岔巴沟流域王武沟小流域为研究区,基于无人机航摄影像,以2017年陕北\     

视屏遥感图像外摄成像技术研究

介绍了通用照相方式成像的技术方法和具体步骤,指出了为获取高质量的图像而在实际工作中应注意的问题及可采取的措施。通用照相方式作为视屏遥感图像成像的一种方法,有其极为广泛的实用价值。     

秋水仙素注射大蒜花苞诱导四倍体的研究

为获得染色体加倍的大蒜植株,用0.05%、0.10%、0.15% 和0.20% 的秋水仙素注射苍山糙蒜和金蒜3 号的花苞,并在不同生长调节剂组合的MS 培养基上培养花苞内形成的气生鳞茎,当再生体系建立后,对根尖进行倍性鉴定。结果表明,MS 基本培养基添加0.05 mg·L-1 NAA 和2.0 mg·L-1 KT 能诱导较多的气生鳞茎萌发,直径4～5 mm 的气生鳞茎萌发率最高,且苍山糙蒜气生鳞茎的萌发率整体比金蒜3 号高。秋水仙素注射花苞后,金蒜3 号的花苞死亡率远远高于苍山糙蒜。随着秋水仙素浓度增大,花苞内形成气生鳞茎数不断降低,染色体加倍率升高。苍山糙蒜以0.20% 秋水仙素浓度处理下四倍体诱导率最高,为7.69%;金蒜3 号以0.15% 秋水仙素浓度处理下四倍体诱导率最高,为11.76%。     

A comparison of different survey methods for assessing gap parameters in old-growth forests

Examining the actual state of canopy gaps in forests is critically important for evaluating forest community structure and dynamics, and for comparing gap disturbance regimes in different forests. We, therefore, re-examined our own previously published data from three studies of three different gap survey methods - the Belt transect method, the canopy coverage census method, and an aerial photography method - in order to ascertain how gap parameters (area, size and density of gaps, and related gap characteristics) obtained from these methods differ from each other. We found that the Belt transect method is easy to apply and practical in the field, and the method used for gap measurement is simple. Mean gap size and size distribution obtained using the Belt transect method were not different statistically from those of the other gap survey methods, and quantified gap parameters were in the range recorded for other forests of the world. For preliminary studies of gap dynamics in different forest types, an easy, speedy and workable gap survey method is needed. In addition, surveying a large number of gaps and a large area improve the accuracy of the method. We conclude that the Belt transect method is most suitable method for preliminary gap surveys in the field.     

Soil carbon mapping using on-the-go near infrared spectroscopy, topography and aerial photographs

Efficient tools for accurate soil carbon (SC) mapping are imperative for large scale assessment of total SC stocks and their changes in time as well as for site-specific tailoring of agricultural management practices. On-the-go near infrared (NIR) reflectance spectroscopy has been used recently in aid to the conventional, laborious and expensive soil analyses, since NIR measurements are taken in-situ quickly and non-destructively. However, NIR spectrum data need to be effectively calibrated with conventionally measured SC. Our objectives are to compare calibration approaches, including pre-processing transformations (Savitzky-Golay derivatives, standard normal variate and mean centering) and multivariate statistical methods (principal component regression, partial least squares, partial least squares leaving one-outlier-out) for using NIR spectra data as SC predictor, to evaluate NIR reliability in predicting SC under low carbon contents typical for Midwest Alfisols; and finally to compare predictions of SC by using three sources of auxiliary information (NIR spectral data, visible-NIR reflectance obtained from aerial photographs and topographical features). No improvements in calibration accuracy were observed when using pre-processing transformations. Partial least squares (RMSE = 1.90) tended to perform better than principal component regression (RMSE = 1.96); especially when spectral-NIR outliers are dropped (RMSE = 1.68). Our results suggested that visible-NIR data from aerial photographs used along with topographical attributes outperformed on-the-go spectral NIR data. Topographical data improved prediction in the models with aerial photograph visible-NIR data; however no improvement was noticed when used with spectral-NIR data. Though, NIR spectral data is frequently used as a proxy for SC prediction, we notice that this auxiliary information is not well suited under all scenarios. Particularly, when SC levels are low and the range of SC data is narrow, as in this study, NIR was only moderately successful in predicting SC.     

Trends in Decision Support Systems for Cropping Systems Analysis: Examples from Nebraska

SUMMARY

Over the past 20 years, decision support systems (DSS) have been applied to a number of important problems in cropping systems analysis. Seven interrelated information technologies are currently driving new opportunities for decision support systems: global positioning systems (GPS), sensors for direct field measurements, variable rate application technology, remote sensing, data communication systems, geographic information systems (GIS), and personal computers. These technologies were used in three modeling examples designed to develop DSS at three different levels: competition between individual plants in an uneven stand (modeled at hourly time steps and sub-meter resolution), historical analysis of county-level yields (100 year sequence at multi-kilometer resolution), and yield map modeling (daily time step for a 64 ha field). In each case, a sequential analysis of model predictions helped identify additional data or algorithms needed to model the system at its appropriate scale. Continued progress in system modeling combined with projected growth in computer power, near-term improvements in remote sensing and precision farming equipment, and new developments in the automation of data exchanges over the Internet should all contribute to expanded use of DSS for cropping systems analysis in the future.