蜜环菌不同特化菌体的HPLC-DAD图谱比较

采用麦芽汁液体培养基培养蜜环菌获得菌丝体，采用麦芽汁半固体培养基培养蜜环菌获得蜜环菌菌素、皮壳状菌丝和子实体。以高效液相色谱-二极管阵列检测法（High Performance Liquid Chromatography-Diode Array detector，HPLC—DAD）比较四种菌体的甲醇提取物的成分差异。液体培养的蜜环菌菌丝体与固体培养的蜜环菌菌素、皮壳状菌丝和子实体的蜜环菌素类成分有明显差别。图谱分析表明，菌素与皮壳状菌丝的成分接近，与子实体和液体培养菌丝体之间有较大差别。     

Relationship between vegetative and rhizome characters and final rhizome yield in micropropagated ginger plants (Zingiber officinale Rosc.) over two generations

Correlation and path analysis for yield and yield contributing characters in two types of micropropagated ginger plants (plantlets directly regenerated from aerial stem explants and plantlets regenerated from aerial stem derived callus) were carried out over first and second generations in two varieties viz. var. ‘Jamaica’ and var. ‘Varada’. Irrespective of the regeneration method, the in vitro derived plants showed high positive correlation and maximum positive direct effect of circumference of cormlets, length of cormlets and number of cormlets with the rhizome yield in the first generation. But tiller number exhibited negative correlation and negative direct effect with the rhizome yield in the first generation. In the second generation of the aerial stem regenerated plants, tiller number, number of nodes per cormlets, circumference of cormlets, number of cormlets and plant height exhibited high positive correlation and maximum direct effect with rhizome yield. However, in the second generation also, the callus regenerated plants showed the same trend as in the first generation. Even though the tiller number showed positive significant correlation with rhizome yield, it showed negative direct effect with the yield.     

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。     

我国农业无人机航空植保技术现状与发展趋势分析

无人机航空植保技术是一种现代化的施药方式,适合复杂地形和小面积作业,在我国南方水田、丘陵山地等地有着较好应用前景.但目前,我国无人航空植保技术的研究还处于初级阶段.本文在介绍国外无人机航空植保技术现状的基础上,分析了我国无人机航空植保技术的发展水平及存在的问题,并提出无人机植保施药技术的发展方向与技术需求,仅供参考.     

Length and classification of natural and created forest edges in boreal landscapes throughout northern Sweden

Forest edges have numerous implications for structure and function of forest ecosystems. Previous studies on edge quantity have used broad classifications. However, edge influence is driven by the contrast in vegetation structure between adjoining ecosystems, and thus we need detailed site-specific data to assess the role of edges in forests. We studied the variability of sharp edges in 28 boreal landscapes (4 km × 4 km) across an 830 km gradient throughout northern Sweden. Our objectives were: (1) to compare the length of natural and created edges, (2) to classify edges in detail by edge origin, maintenance and forest attributes, and (3) to examine relationships between length of edge and landscape variables. Data were collected using stereo-interpretation of high spatial resolution colour infrared aerial photographs, in combination with line intersect sampling and plots. The length of edge varied from 12 to 102 m ha⁻¹ among landscapes, with an overall mean of 54 m ha⁻¹. Created edges dominated most landscapes (mean 33 m ha⁻¹) and had greater variability than natural edges (mean 21 m ha⁻¹). Maintained edges (e.g. roads, agricultural land) were more abundant than regenerating edges caused by logging. Thirty percent of total edges adjoined narrow linear features. Seventy percent adjoined wider patches and showed high variability (35 classes). Overall, high-contrast edges towards mature forest dominated, i.e. ones that may experience strong edge influence. The amount of edge increased with percent of landscape affected by disturbance, and decreased with latitude and elevation. This study shows that edges are both abundant and highly variable in boreal forests and that forestry is the main driver behind edge creation. Detailed classification of edges based on site-specific forest and patch attributes may help to estimate edge influence at landscape level, and can guide experimental design for examining the impact of edges on structure and function of forest ecosystems.     

Feedbacks between fuel reduction and landscape homogenisation determine fire regimes in three Mediterranean areas

In densely populated areas like the Mediterranean, wildfire extent is mostly limited by fire suppression and fuel fragmentation. Fire is known to spread more easily through high fuel loads and homogenous terrain and it is supposed to reduce fuel amount and continuity, creating a negative feedback. Here we combine information from administration fire records, satellite imagery fire scars and land use/cover maps to asses the effects of fire on landscape structure and vice versa for three areas in Catalonia (NE Spain). We worked with three spatial focuses: the actual fire scar, 1 km² squares and 10 km² squares. In these regions agriculture land abandonment has lead to increased fuel continuity, paralleled by an increment of fire size. We confirm that fire spread is facilitated by land use/cover types with high fuel load and by homogeneous terrain and that fire reduces fuel load by transforming forests into shrublands. But we also found that fire increased landscape homogeneity, creating a positive feedback on fire propagation. We argue that this is possible in landscapes with finer grain than fire alone would create. The lack of discontinuities in the fuel bed diminishes the extinction capacity of fire brigades and increases the risk of large fires. We recommend that fire management should focus more on conservation of the traditional rural mosaic in order to prevent further increases in fuel continuity and fire risk.     

应用TM卫星像片进行树种分布解析的研究

本文论述了ＴＭ卫星像片的图像处理技术，以日本北海道苫小牧地区森林为例，进行不同树种的计算机自动分类，并给出多光谱图像上不同年龄树种的灰度与年龄之间的相关图。研究结果表明：云杉属、冷杉、落叶松的反射率随年龄增大而降低，用最大似然法监督分类，可以很好地区分不同树种，得出苫小牧地区森林分布情况的遥感图像。     

Evaluation of direct and diffuse radiation densities under forest canopies and validation of the light diffusion effect

In order to consider the effects of light quality on the growth of understory plants, both the direct and diffuse components of solar radiation must be evaluated. However, the basis for choosing the threshold between the two components of radiation has not been systematically determined. We evaluated the basis and methods for separating direct and diffuse radiation under field conditions. Daily courses of direct and diffuse photosynthetic photon flux densities (PPFDs) over and under canopies were measured with quantum sensors and were predicted from hemispherical photographs. We proposed a new variable, called the diffuse coefficient of canopy (dc), to compensate for the increase in the diffuse radiation component as the sunlight passes through the overstory canopy. dc was highly correlated with canopy coverage (cc) (dc = 0.01cc – 0.3, r ² = 0.95). For woodland sites, PPFD can be predicted from hemispherical photographs according to the following equations: W _dir = S _out( – dc) ^M sin and W _dif = S _out (0.271 – 0.294( – dc) ^M ) sin, where W _dir and W _dif are the direct and diffuse radiation components in woodland sites, S _out is the extraterrestrial PPFD normal to the solar beam, is the atmospheric transmittance, M is the optical airmass number and is the solar elevation. The daily courses of PPFD and sunflecks under canopies can be estimated from hemispherical photographs when the effects of dc are considered.     

Light distribution in scattered-trees open woodlands in Western Spain

We have studied the percentage of radiation transmitted through the tree canopy to the underlying pasture and crops in dehesas of Southwest Spain by means of fish-eye photographs taken at different distances from the tree. Thirty-six trees were studied covering all the diametric classes (0.1–14 m canopy width) of two stands, with mean density of 19 mature trees ha⁻¹. Intercepted light decreased with distance following an logistic curve, indicating a rapid increase in the light availability with distance from the tree. For mature trees, radiation was constant beyond 20 m. Applying a multivariable regression light equation, distance, stem diameter and canopy width explained more than 88% of the light variability for each orientation studied. A simple model was built up from light equations, tree growth curves and allometric relationships. From this model, we have estimated that radiation available for crops and pasture decreased up to 21% due to the presence of trees in a standard dehesa with 24 mature trees ha⁻¹ and 13% of canopy cover. In addition, we have generated different radiation maps of virtual dehesas differing in tree age, density and arrangement, which could be useful to determine optimal tree planting schemes and consequent pruning and thinning regimes.     

Effect of management on the spatial spread of mountain pine beetle (Dendroctonus ponderosae) in Banff National Park

To evaluate control measures, the spread of mountain pine beetles, Dendroctonus ponderosae, in management and monitoring regions in Banff National Park was analyzed for years 1997 to 2004. The Park allowed mountain pine beetles to follow their natural course in a monitoring zone (74,041 ha), whereas in a management zone (45,997 ha) an extensive eradication program was established in 2001 which included baiting mountain pine beetles and cutting and burning all colonized trees. We used data collected from an annual aerial survey and the geo-referenced location of trees that were cut and removed to assess if the area colonized and the spatial extent of mountain pine beetles differed between the two zones. After 4 years, the control measures did not significantly affect the area colonized by mountain pine beetles, and in 2004 mountain pine beetles were still expanding in both zones, although at a slow rate (1.23 ha per year). The spatial extent and the rate at which 500 m × 500 m cells (25 ha) were colonized were much reduced in the management zone. Thus, the management program appeared to have reduced the success of long distance movement as measured by colonizing new 25 ha cells, but short distance dispersal remained successful as indicated by the continued increase in area colonized. The effectiveness of control measures was probably limited by the number of colonized trees that were missed and by survival rates determined by other untested factors.