毛乌素沙地飞播后植被演替规律研究——以内蒙古乌审旗为例

通过对乌审旗境内飞播后的毛乌素沙地植被进行调查研究,初步得出以下结论:毛乌素沙地的演替规律是,第一阶段为先锋阶段,植被表现为籽蒿+羊柴群落;第二阶段为过渡阶段,植被表现为羊柴+油蒿群落;第三阶段植被表现为羊柴群落。人为干扰在一定程度上决定着羊柴群落的演替,合理放牧和经营管理可使羊柴群落处于相对稳定的阶段。     

应用鱼眼全景像片计算林隙内日照条件的图解方法

林隙生态机理已成现代森林生态学研究的热点，尤其是林隙内光照条件的变化对树种更新和生长具有重要的生态效应。但是，由于林隙结构极为复杂，难以精确地测量林隙上方和周围树冠空隙的透光情况。为此，本文应用鱼眼全景摄影方法拍摄了林隙结构的全景图象，建立了在橡片上直接计算林隙遮蔽效应的数学模型，并在林隙全景像片上绘制出太阳视轨道，就可以定量和直观地表述林隙内日照条件的变化规律。     

A novel method for estimating tree dimensions and calculating canopy volume using digital photography

Studies on plant phenology and browse capacity require effective methods to rapidly quantify plant dimensions such as tree height, height of maximum canopy diameter, height of first leaves, maximum canopy diameter, and diameter of trunk(s) at height of first leaves. Here we describe a method for estimating tree dimensions and calculating canopy volume using a measuring staff (for calibration), a digital camera and our VolCalc software. The method requires a photograph be taken of the measuring staff placed next to an object whose measurements are to be determined. The two objects must be adjacent to one another in the photograph. For rapid analysis, multiple photographs of different objects can be taken over a short period of time using the measuring staff. The method is not limited to plants and can be used to determine, for example, browser height, height at which browsers feed, and primate resource abundance. The method has been tested in the field and provides a fast and precise tree dimension parameter estimation option, where sampling time is of the essence. Test results compare well to alternative methods currently utilised, showing improved precision and faster field data collection times, which are important to researchers and ecologists.     

植被覆盖度的照相测量及其自动计算

植被覆盖度是描述陆地表面植被特征的一个重要参数.快速准确的测量植被覆盖度,对研究植被覆盖与土壤侵蚀关系,植被覆盖的水土保持效益,以及土壤侵蚀预报等具有重要意义.在多年实践的基础上研制出的便携型植被覆盖度摄影仪,适用于野外平地或山坡的植被覆盖度的照相测量,能方便地调节相机距地表面高度和增强相机的拍摄稳定性.同时开发了便携型植被覆盖度摄影仪的配套软件--植被覆盖度自动计算系统(PCOVER),能对获取的植被图像进行自动判读并估算植被覆盖度,实际应用显示有很好的判读精度.     

Forest fragmentation and duration of forest tent caterpillar (Malacosoma disstria Hübner) outbreaks in northern hardwood forests

In northern forests dominated by aspen (Populus spp.), the duration of outbreaks of forest tent caterpillar (Malacosoma disstria Hübner) has been reported to increase with forest fragmentation. This relationship has not been tested in other forest types affected by this widespread native defoliator. From 2002 to 2007, a large-scale outbreak of this insect in the northeastern United States defoliated millions of hectares, with sugar maple (Acer saccharum Marsh.) the primary host. We used digital defoliation maps generated from aerial surveys and national land cover data to assess the effect of fragmentation on outbreak duration in areas of NY, MA, VT, and NH. We found that outbreak duration increased with forest cover and decreased with the forest edge, in opposition to the pattern previously reported for aspen-dominated forests in Canada. This pattern was significant from plot sizes ranging from 100 m to 1000 m in radius. The relationship between FTC and its natural enemies, which was postulated to underlie the effect of fragmentation on outbreaks in aspen forests, may be affected differently in northern hardwood forests, or other factors may be more important in determining outbreak duration in this forest type.     

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。     

秀珍菇菌种复壮方法比较

以从秀珍菇(Pleurotus geesteranus)污染菌包中分离得到的3个秀珍菇菌株为出发菌株,采用挑取尖端菌丝、基内菌丝及气生菌丝3种方法进行复壮处理,共获得处理菌株8个。以出发菌株为对照,比较处理菌株的菌落形态、菌丝生长速度及菌丝生物量,并通过出菇实验以及dsRNA检测,对不同复壮方法的复壮效果进行评价。结果表明:尖端菌丝和基内菌丝挑取法能显著提高出发菌株的菌丝生长速度和生物量,可以缩短出菇周期并提高出菇产量;而气生菌丝挑取法则不能对出发菌株进行复壮,其菌丝生物量和出菇产量反而比出发菌株有所降低。     

基于航空影像的树冠提取方法研究

用高空间分辨率遥感影像对单木树冠进行自动提取和轮廓描绘是近年来林业遥感领域研究的热点。本文以覆盖实验区的航空影像为例,采用面向对象的多尺度分割方法,逐级对植被对象、树冠对象和分树种模式进行分割,有效地提取了影像中的树冠大小信息。     

Medium-term gully headcut retreat rates in Southeast Spain determined from aerial photographs and ground measurements

This paper deals with gully retreat rates at different time scales, whereby the short-term time scale may span a time interval of 1–5 years, the medium-term time scale a time interval of 5–50 years, and the long-term time scale a time interval of more than 50 years. An analysis of high-altitude aerial photographs in combination with ground measurements allowed us to quantify volumetric gully-head retreat rates for 12 permanent gullies in Southeast Spain (Guadalentin and Guadix study areas) over a 40–43 year time interval (medium-term time scale). This resulted in an average retreat rate (V_e) of 17.4 m³ year⁻¹. A power relationship between drainage-basin area (A) and medium-term volumetric gully-head retreat rate, V_e=0.069A^0.380 (R²=0.51, n=21), was found by combining the gully-head retreat rates obtained in this study with those obtained by a dendrochronological method. The exponent (b) and the coefficient of determination (R²) of the power relationships V_e=aA^b increases from the short-term to the long-term time scale, expressing the increasing importance of drainage-basin area in gully development with time. Considerable differences between gully-head retreat rates measured at the short and medium-term time scales at individual gullies showed the importance of land-use changes and unsuccessful management practices on gully-head retreat, and the episodic nature of gully-head retreat when piping and tension cracking are involved. Higher gully-head retreat rates are obtained at the medium-term time scale compared to the short-term time scale but the differences are not significantly different at α=10%. The medium-term methods tend to measure proportionally more high gully retreat rates, but less extreme values compared to the short-term method. This is explained by a more equal distribution of extreme rainfall events both in space and time at a longer-term time scale, and hence a higher probability of measuring the average effect of both small and extreme rainfall events at each gully.