联合GF-6和Sentinel-2红边波段的森林地上生物量反演

光谱反射率能反映地物差异,是森林地上生物量（Aboveground Biomass,AGB）遥感反演的理论基础。红边波段处于近红外与红光波段交界处快速变化的区域,能对植被冠层结构和叶绿素含量的微小变化做出快速反应,对植被生长状况较敏感。研究以GF-6和Sentinel-2多光谱影像作为数据源,结合野外调查AGB数据,构建落叶松和樟子松AGB线性和非线性估测模型,通过比较模型精度选择最优模型进行森林AGB反演和空间分布制图。结果表明：GF-6和Sentinel-2影像红边波段反射率与落叶松、樟子松AGB均呈显著相关（P<0.05）,红边波段对AGB估测较敏感。多变量估测模型整体估测效果优于单变量模型,所有模型中多元线性回归模型取得了最优的决定系数（落叶松R²=0.66,樟子松R²=0.65）和最低的均方根误差（落叶松RMSE=31.45 t/hm²,樟子松RMSE=54.77 t/hm²）。相比单个数据源,联合GF-6和Sentinel-2影像构建的多元线性回归模型估测效果得到了显著提升,模型RMSE对于落叶松和樟子松AGB估测分别最大降低了22.9%和11.2%。增加红边波段进行AGB估测能显著提高模型估测精度,三组数据源分别加入红边波段信息后进行建模,模型RMSE得到了显著降低。GF-6拥有800 km观测幅宽和高效的重访周期,可以快速地提供大尺度时间序列数据,在森林地上生物量反演和动态监测方面有着很大潜力。     

Performance of the predator Amblyseius swirskii (Acari: Phytoseiidae) on greenhouse eggplants in the absence and presence of pine Pinus brutia (Pinales:Pinaceae) pollen

In Turkey, the western thrips Frankliniella occidentalis (Pergande) is a key pest affecting eggplants grown in greenhouses for which an appropriate control strategy is under investigation. It was observed in a previous study that the release of the beneficial predatory mite Amblyseius swirskii (Athias‐Henriot) alone did not result in an effective control of thrips on eggplants. Since pollen is known to improve control efficiency of predators, this study was undertaken to investigate if provision of pollen to eggplants can greatly improve the efficiency of A. swirskii in controlling thrips. The experiments were carried out in both greenhouse and low tunnel. The provision of pollen led to a significant increase in the predator population density on the eggplants but did not result in an effective control of the thrips populations. In this paper, various factors are discussed that could have affected the efficiency of the predatory mite in controlling F. occidentalis on eggplants.     

Pinus taeda forest growth predictions in the 21st century vary with site mean annual temperature and site quality

Climate projections from 20 downscaled global climate models (GCMs) were used with the 3‐PG model to predict the future productivity and water use of planted loblolly pine (Pinus taeda) growing across the southeastern United States. Predictions were made using Representative Concentration Pathways (RCP) 4.5 and 8.5. These represent scenarios in which total radiative forcing stabilizes before 2100 (RCP 4.5) or continues increasing throughout the century (RCP 8.5). Thirty‐six sites evenly distributed across the native range of the species were used in the analysis. These sites represent a range in current mean annual temperature (14.9–21.6°C) and precipitation (1,120–1,680 mm/year). The site index of each site, which is a measure of growth potential, was varied to represent different levels of management. The 3‐PG model predicted that aboveground biomass growth and net primary productivity will increase by 10%–40% in many parts of the region in the future. At cooler sites, the relative growth increase was greater than at warmer sites. By running the model with the baseline [CO₂] or the anticipated elevated [CO₂], the effect of CO₂ on growth was separated from that of other climate factors. The growth increase at warmer sites was due almost entirely to elevated [CO₂]. The growth increase at cooler sites was due to a combination of elevated [CO₂] and increased air temperature. Low site index stands had a greater relative increase in growth under the climate change scenarios than those with a high site index. Water use increased in proportion to increases in leaf area and productivity but precipitation was still adequate, based on the downscaled GCM climate projections. We conclude that an increase in productivity can be expected for a large majority of the planted loblolly pine stands in the southeastern United States during this century.     

The suppression of Dendroctonus frontalis and subsequent wildfire have an impact on forest stand dynamics

Question: Interacting disturbance effects from Dendroctonus frontalis outbreaks and wildfire are thought to maintain Pinus spp. composition in the southeastern U. S. Our objective was to assess forest composition, structure, and succession following the interaction of two frequently occurring disturbance events in southern Pinus spp. forests: cut‐and‐leave suppression, a commonly used means for managing D. frontalis outbreaks, and wildfire. Location: Western Gulf Coastal Plain, Louisiana, USA. Method: Pinus taeda stands with cut‐and‐leave suppression and subsequent wildfire were compared to stands undisturbed by D. frontalis but with the same wildfire events twenty years after Pinus spp. mortality. The woody plant community was assessed in three different size classes and used to predict future forest types with the Forest Vegetation Simulator (50 years). Results: P. taeda is the most abundant (> 50%) species of saw‐ and poletimber‐sizes following cut‐and‐leave suppression with wildfire and in stands only with fire. Using canonical correspondence analysis, vegetation assemblages were primarily explained by slope position and elevation (7.6% variation explained). Fire intensity and stand age also accounted for variance in the ordination (4.4% and 3.1%, respectively). Dominant and co‐dominant P. taeda forest types were predicted by the model to be the most abundant forest types in each disturbance regime. In addition, new regeneration represents high hazard for future mortality from D. frontalis. Conclusion: Our study demonstrates that cut‐and‐leave suppression with additional wildfire disturbance maintains P. taeda composition, and does not alter forest composition differently from stands receiving only wildfire. As a result, predicted Pinus spp. basal area under both disturbances is great enough to facilitate future bark beetle disturbance.     

2‐(Undecyloxy)‐ethanol is a major component of the male‐produced aggregation pheromone of Monochamus sutor

The small white‐marmorated longicorn beetle, Monochamus sutor (L.) (Coleoptera: Cerambycidae), is widely distributed throughout Europe and Asia. It is a potential vector of the pine wood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle, the causal agent of the devastating pine wilt disease. Volatiles were collected from both male and female beetles after maturation feeding. In analyses of these collections using gas chromatography (GC) coupled to mass spectrometry, a single male‐specific compound was detected and identified as 2‐(undecyloxy)‐ethanol. In analyses by GC coupled to electroantennography the only consistent responses from both female and male antennae were to this compound. Trapping tests were carried out in Spain, Sweden, and China. 2‐(Undecyloxy)‐ethanol was attractive to both male and female M. sutor beetles. A blend of the bark beetle pheromones ipsenol, ipsdienol, and 2‐methyl‐3‐buten‐2‐ol was also attractive to both sexes in Spain and Sweden, and further increased the attractiveness of the 2‐(undecyloxy)‐ethanol. The host plant volatiles α‐pinene, 3‐carene, and ethanol were weakly attractive, if at all, in all three countries and did not significantly increase the attractiveness of the blend of 2‐(undecyloxy)‐ethanol and bark beetle pheromones. 2‐(Undecyloxy)‐ethanol is thus proposed to be the major, if not only, component of the male‐produced aggregation pheromone of M. sutor, and its role is discussed. This compound has been reported as a pheromone of several other Monochamus species and is another example of the parsimony that seems to exist among the pheromones of many of the Cerambycidae. Traps baited with 2‐(undecyloxy)‐ethanol and bark beetle pheromones should be useful for monitoring and control of pine wilt disease, should M. sutor be proven to be a vector of the nematode.     

Canopy cover and understory composition determine abundance of Vaccinium myrtillus L., a key plant for capercaillie (Tetrao urogallus), in subalpine forests in the Pyrenees

Background: The dwarf shrub Vaccinium myrtillus – with high cover, height, and fruit production – benefits capercaillie (Tetrao urogallus).

Aims: Our aim was to quantify landscape (e.g. elevation, geographic location, and precipitation), site (e.g. overstorey cover and stoniness) and very fine scale factors (e.g. spatial associations in the understorey) that affect cover, height, and fruit production of V. myrtillus in subalpine forests in thePyrenees, with understorey usually dominated by Rhododendron ferrugineum.

Methods: We sampled 155 plots (0.5 m × 5 m) in six sites. For each plot, in the understorey layer, we assessed species cover, height for R. ferrugineum and V. myrtillus, number of total fruits in V. myrtillus, and spatial associations among V. myrtillus and the remaining cover types.

Results: Overstorey cover negatively influenced V. myrtillus cover, its height, and particularly, the number of fruits, which was also negatively influenced by R. ferrugineum cover. Associations between R. ferrugineum and V. myrtillus were site dependent, while V. myrtillus showed mostly positive associations with grasses and mosses.

Conclusions: Reducing overstorey and R. ferrugineum cover has the strongest positive effect on increasing V. myrtillus fruit production, but with additional positive effects on V. myrtillus cover and height. Increases in grass and moss coverage could favour V. myrtillus.     

The effects of ultraviolet-B radiation on loblolly pine. I. Growth, photosynthesis and pigment production in greenhouse-grown seedlings

One-year old loblolly pine ( Pinus taeda L.) seedlings were grown in an unshaded greenhouse for 7 months under 4 levels of ultraviolet-B (UV-B) radiation simulating stratospheric ozone reductions of 16, 25 and 40% and included a control with no UV-B radiation. Periodic measurements were made of growth and gas exchange characteristics and needle chlorophyll and UV-B-absorbing-compound concentrations. The effectiveness of UV-B radiation on seedling growth and physiology varied with the UV-B irradiance level. Seedlings receiving the lowest supplemental UV-B irradiance showed reductions in growth and photosynthetic capacity after only 1 month of irradiation. These reductions persisted and resulted in lower biomass production, while no increases in UV-B-absorbing compounds in needles were observed. Seedlings receiving UV-B radiation which simulated a 25% stratospheric ozone reduction showed an increase in UV-B-absorbing-compound concentrations after 6 months, which paralleled a recovery in photosynthesis and growth after an initial decrease in these characteristics. The seedlings grown at the highest UV-B irradiance (40% stratospheric ozone reduction) showed a more rapid increase in the concentration of UV-B-absorbing compounds and no effects of UV-B radiation on growth or photosynthetic capacity until after 4 months at this irradiance. Changes in photosynthetic capacity were probably the result of direct effects on light-dependent processes, since no effects were observed on either needle chlorophyll concentrations or stomatal conductance. Further studies are necessary to determine whether these responses persist and accumulate over subsequent years.     

Greenhouse Gas and Energy Life Cycle Assessment of Pine Chemicals Derived from Crude Tall Oil and Their Substitutes

Pine chemicals are co‐products of papermaking that are upgraded into diverse products from inks to adhesives. They can also be utilized for energy purposes. This research investigates the carbon and energy life cycle assessment (LCA) of pine chemicals derived from crude tall oil (CTO). The study goals are to determine the cradle‐to‐gate carbon and energy footprint for CTO‐derived chemicals, compare CTO‐derived chemicals to their likely substitutes, and calculate the carbon and energy effects of shifting CTO resources from current chemical production to biodiesel production. The data collected represent 100% of the U.S. and 90% of the European CTO distillation industry for 2011. This analysis is the first industry‐level LCA of pine chemicals. The carbon footprint for CTO‐derived pine chemical products is 50% lower than the likely mix of alternative products, including hydrocarbon resins for rubber, ink, and adhesive, alkyl succinic anhydride for paper size, and heavy fuel oil for heat. Current and proposed European policies could result in CTO being classified as renewable biomass for energy production, creating incentive to convert CTO into fuel rather than chemicals. The differences in the carbon and energy footprints of utilizing CTO for biodiesel versus chemicals are not meaningful when comparing European CTO biodiesel, which displaces conventional diesel, to European CTO‐derived chemicals, which displace the previously discussed substitutes. Therefore, there is no additional carbon or energy benefit that accrues by diverting CTO from current chemical feedstock applications to use for biodiesel production in Europe.     

利用RAPD标记和单株树大配子体构建马尾松的分子标记连锁图谱

利用300个随机的寡核苷酸引物和马尾松(Pinus massoniana Lamb.)种子的胚乳(大配子体)产生的随机扩增多态性DNA(RAPD)分子标记,进行马尾松标记连锁图谱的构建。经筛选共获得64个稳定的RAPD标记,利用多点连锁分析,其中的48个标记分属于13个不同的连锁群(连锁对),该图谱覆盖的基因组总长度约为692.5cM(centimorgan),标记间平均距离约为14.7cM,它为马尾松连锁图谱的构建提供了一个连锁框架。