Bryophytes on tree trunks in natural forests, selectively logged forests and cacao agroforests in Central Sulawesi, Indonesia

Forest disturbance and transformations into agricultural land alter tropical landscapes at drastic rates. Here, we investigate bryophyte assemblages on trunk bases in natural forest, selectively logged forest and cacao agroforests that are shaded by remnants of natural forest in Central Sulawesi. Overall, bryophyte richness per site did not differ between forest types. However, mosses and liverworts reacted differently in that moss richness was lowest in cacao agroforests, whereas liverwort communities were equally rich in all forest types. In terms of cover, mosses remained unaffected while liverwort cover decreased significantly in disturbed forest. Species composition of bryophytes clearly changed in cacao agroforests as compared to natural forests and selectively logged forests. In particular some drought-sensitive species were rare or absent in cacao agroforests and were replaced by drought-tolerant ones, thus underlining the importance of microclimatic changes. Moreover, differences in bryophyte species composition between large and small trees were only pronounced in cacao agroforests, presumably due to concomitant changes in stemflow of precipitation water. In conclusion, the bryophyte assemblages of selectively logged forests and cacao agroforests were as rich as in natural forest, but species turn-over was particularly high towards cacao agroforests probably due to microclimatic changes. Maintenance of shade cover is crucial to the conservation of the drought-sensitive forest species.     

高海拔林区林下培菌生产鸡腿菇的研究初报

在500m～1200m高海拔林场内进行“林下培菌”生产仿野生鸡腿菇的研究，结果证明，较之传统大棚或菇房设施化栽培，林下培菌生产仿野生鸡腿菇无需占用耕地，彻底解决了当地鸡腿菇栽培中的“菇粮争地”矛盾；可节省出菇棚等固定资产投资70％以上；另外生物学效率为149％，较之传统菇棚栽培提高40％左右；产出的菇品明显具有野生菇的口感和风味。另外，菌糠废料直接被林地树根就地分解利用，提高了林地土壤肥力，改善了林地土壤结构，提高了林地生产力，减少了人工处理菌糠废料的费用，同时，由于保湿的需要以及出菇管理人员的频繁出入林场操作和巡视，最大限度地降低了森林火险的发生概率。     

Leaf structure and function of sweet cherry tree (Prunus avium L.) cultivars with open and dense canopies

Variations in morpho-anatomy, chemical composition, gas exchange and stem water potential (Ψ_stem) were studied in leaves of Prunus avium L. cultivars with different growth habit: Burlat and Summit (upright, dense canopies), and Van (spreading, open canopy). Light transmittance was highest in Van canopies. Therefore, Van allowed an easier penetration of the visible radiation through the canopy, which improves photosynthetic rates, especially at harvest. Conversely, no differences in Ψ_stem were found among cultivars. Van showed the highest leaf mass per unit area and variations in this parameter were mainly associated with alterations in leaf thickness than in leaf density. Leaves of Summit and Van were thicker than those of Burlat, mainly due to increased palisade and spongy parenchyma thickness. However, Burlat leaves had the highest palisade/spongy ratio. Total chlorophyll concentration per area and the chlorophyll a/b ratio were always higher in Van leaves than in the other two cultivars. In contrast, Van leaves had the lowest concentrations of soluble carbohydrates and starch. In dense canopies of Summit and Burlat, light reduction caused a notable increase in the relative concentration of total phenols. The above results provide useful information about the biological behaviour of sweet cherry cultivars with open and dense canopies in order to help the agronomical decisions regarding the local environmental conditions and the consumers’ preference. In particular, it is important to manipulate factors such as orchard exposure, row orientation, plant spacing, training system and pruning, which are able to reduce shading in the canopy.     

Use of Canopy Temperature Measurements as a Screening Tool for Drought Tolerance in Spring Wheat

Remotely sensed infrared canopy temperatures provide an efficient method for rapid, non-destructive monitoring of whole-plant response to water stress. Field studies were conducted in 1992 and 1993 to evaluate the potential for using canopy temperatures to screen for drought tolerance in wheat. In both years, 12 spring wheat (Triticum aestivum L.) genotypes were grown under two irrigation levels (well-watered and moisture-stressed) imposed between tillering and anthesis with a line-source sprinkler irrigation system. Canopy temperature measurements were taken in well-watered and moisture-stressed plots between 1330 and 1430 h (MDT) on five clear days in 1992 and seven clear days in 1993 during the late vegetative and early reproductive growth periods following closure of the plant canopy. Genotypes exhibited differences in mean canopy temperatures across the two irrigation levels and two years. Klasic consistently had the highest canopy temperature under moisture-stressed conditions, while Bannock and Pondera had the lowest. Bannock, Yecora Rojo and Klasic had the warmest canopies under well-watered conditions, while Vandal, Amidon and Rick had the coolest. Plot-to-plot variation in canopy temperature under water stress conditions was evident for differences in grain yield. Significant correlations between canopy temperature and yield under moisture-stress conditions and drought susceptibility index values indicated the potential for screening wheat genotypes for drought response.     

Phenological development, leaf emergence, tillering and leaf area index, and duration of spring wheat across Europe in response to CO2 and ozone

Phenological development, leaf emergence, tillering and leaf area index (LAI), and duration (LAD) of spring wheat cv. Minaret, grown in open-top chambers at different sites throughout Europe for up to 3 years at each site, were investigated in response to elevated CO₂ (ambient CO₂×2) and ozone (ambient ozone ×1.5) concentrations.

Phenological development varied among experiments and was partly explained by differences in temperature among sites and years. There was a weak positive relationship between the thermal rate of development and the mean daylength for the period from emergence to anthesis. Main stems produced on average 7.7 leaves with little variation among experiments. Variation was higher for the thermal rate of leaf emergence, which was partly explained by differences in the rate of change of daylength at plant emergence among seasons. Phenological development, rate of leaf emergence and final leaf number were not affected by CO₂ and ozone exposure. Responses of tillering and LAI to CO₂ and ozone exposure were significant only in some experiments. However, the direction of responses was consistent for most experiments. The number of tillers and ears per plant, respectively, was increased as a result of CO₂ enrichment by about 13% at the beginning of stem elongation (DC31), at anthesis and at maturity. Exposure to ozone had no effect on tillering. LAI was increased as a result of CO₂ elevation by about 11% at DC31 and by about 14% at anthesis. Ozone exposure reduced LAI at anthesis by about 9%. No such effect was observed at DC31. There were very few interactive effects of CO₂ and ozone on tillering and LAI. Variations in tillering and LAI, and their responses to CO₂ and ozone exposure, were partly explained by single linear relationships considering differences in plant density, tiller density and the duration of developmental phases among experiments. Consideration of temperature and incident photosynthetically active radiation in this analysis did not reduce the unexplained variation. There was a negative effect of ozone exposure on leaf area duration at most sites. Direct effects of elevated CO₂ concentration on leaf senescence, both positive and negative, were observed in some experiments. There was evidence in several experiments that elevated CO₂ concentration ameliorated the negative effect of ozone on leaf area duration. It was concluded from these results that an analysis of the interactive effects of climate, CO₂ and ozone on canopy development requires reference to the physiological processes involved.     

基于反射率及导数的草原植被冠层光合有效吸收分量高光谱反演

利用ASD便携式野外光谱仪和光量子仪实测了6种草原植被类型关键生育期的反射光谱数据和光合有效辐射值,利用可见光波段处反射率及近红外波段区处一阶导数分别与fPAR建立逐步回归方程,同时,将各波段反射率与各波段导数光谱建立逐步回归方程。结果表明:典型草原光合有效辐射分量与可见光反射率相关性好于近红外波段反射率,其中在405和470 nm波段相关性最好;fPAR与一阶导数相关关系在855和965 nm波段处较强。fPAR与405和470 nm反射率以及965 nm一阶导数的多波段逐步回归分析结果取得了较单波段和NDVI最优的估算效果,R²达0.939。利用高光谱数据进行fPAR估算时,需要综合考虑可见光和近红外波段信息,同时也要充分考虑反射率与反射率导数的方法。水分强吸收的光谱波段具有提高fPAR估算精度的潜力。     

小型渔船单拖网双缝口网板研究

为解决小型渔船单拖网平面矩形网板升阻比偏低、扩张力小、阻力大的问题,研制了双缝口平面矩形网板。14．1kW渔船,网板主尺度1．7m×0．5m,双缝口结构,第一缝口设在距网板前缘0．65m之处,缝口角度33°,缝口间距9cm,缝口尺度0．35cm×0．02m。海上生产试验表明;新型网板扩张力比普通网板提高18．7％以上,增加产量23．8～32．8％,增加产值31．1～40．6％。专家鉴定认为,本研究填补山东省空白,在同级单船底拖网产量中居国内领先水平。     

Urban density does not impact tree growth and canopy cover in native species in Melbourne,Australia

Trees provide multiple ecosystem services in urban centers and increases in tree canopy cover is a key strategy for many municipalities. However, urban trees also experience multiple stresses and tree growth can be impacted by urban density and impervious surfaces. We investigated the impact of differences in urban form on tree growth in the City of Merri-bek, a local government area in metropolitan Melbourne, which is the temperate climate zone. Merri-bek has a gradient in population density and urban greenness from north to south, and we hypothesized that tree growth in the southern areas would be lower because trees were more likely to have less access to water with high levels of impervious surfaces. We selected three common native evergreen species, Eucalyptus leucoxylon, Melaleuca linariifolia, and Lophostemon confertus that exhibit differences in climate vulnerability and assessed the tree canopy expansion in four urban density zones in Merri-bek between 2009 and 2020 using aerial image analysis. The differences in urban form did not significantly influence tree canopy growth and all species showed similar canopy expansion rates. However, smaller trees showed a greater relative canopy increase in the ten years, whereas larger trees had a greater absolute canopy growth. Thus, older and larger trees should be protected and maintained to achieve the canopy expansion. Our study indicated that differences in urban form are unlikely to have major impacts on the growth and canopy expansion of well adapted native tree species in open, suburban centers.     

基于近地高光谱与TM遥感影像的冬小麦冠层含水量反演

为探讨利用近地高光谱和TM遥感影像数据评估作物冠层水分状况的可行性,以北京顺义通州为研究区域,以冬小麦为研究对象,首先基于Landsat TM5的光谱响应函数,利用地面实测的冬小麦全生育期冠层高光谱窄波段反射率数据来模拟TM5卫星宽波段反射率,然后利用模拟的TM5数据的NIR波段(第4波段)和2个SWIR波段(第5和7波段)反射率分别构建水分指数(WI)和归一化差异水分指数(NDWI),并利用地面实测数据建立冠层叶片含水量(LWC)和等效水厚度(EWT)的遥感估算模型,最后选取最优的水分估算模型,利用TM5卫星遥感影像数据对研究区域小麦冠层水分含量进行反演与应用。结果表明,利用TM5数据中SWIR第5波段比第7波段构建的水分指数更有优势;WI对估算LWC的效果较好,而NDWI在EWT估算方面效果较好,应用TM5宽波段模拟数据模型验证的冬小麦冠层含水量的r2和RMSE分别为0.57和0.51、3.89%和0.024。同时从TM遥感影像的反演结果来看,开花期的冬小麦冠层水分高于拔节期。     

黄淮冬麦区晚霜冻易发时段冠层内最低气温分布及估算

利用2016年和2017年3月中旬?4月下旬两次典型低温过程中,冬小麦田间不同高度逐小时气象观测数据,分析晚霜冻易发时段冬小麦冠层内最低气温出现高度及其变化规律,构建基于150cm高度处气象因子和地表0cm温度的冠层内最低气温估算模型。结果表明：（1）与150cm高度相比,两次典型低温过程中0℃以下气温在冠层高度附近出现时间更早,持续时间更长且温度更低;（2）最低气温总是出现在4/5冠层高度附近,并在2：00?6：00时段,尤以5：00左右发生频率最高;（3）冠层内最低气温与150cm高度处相对湿度、风速的相关性通过了0.01水平的显著性检验,与不同高度气温、不同土壤深度地温的相关性也通过了0.001水平的显著性检验,与地温的相关性随着土壤深度的增加而逐渐降低;（4）冠层内最低气温与150cm高度处气温、风速、相对湿度,以及0cm地温的偏相关系数大小排序表现为,气温＞风速＞地温＞相对湿度;利用以上因子构建基于多元线性回归函数的冠层内最低气温估测模型,其估测值与实测值拟合结果的决定系数达到0.967,均方根误差为0.915。说明基于气象台站常规观测数据构建冠层内最低气温估测模型具备一定可行性,可为冬小麦晚霜冻害的监测预报提供数据支持。