Wood productivity of Prosopis flexuosa D.C. woodlands in the central Monte: Influence of population structure and tree-growth habit

A balance between forest production and protection is hard to achieve in arid zones due to their low potential for wood production. Prosopis flexuosa woodlands are the major woody formations in the Monte desert and are currently in a degraded state due to intense use. The main degradation factors in the study area are overgrazing and firewood extraction. We developed allometric models to estimate the aerial biomass of P. flexuosa, compared annual growth rates of one- and multi-stemmed individuals through dendrochronological methods, and estimated the productivity of four structurally different woodlands in the central Monte. Total dry weight was best estimated by power equations. Annual increments in basal area and dry weight were initially larger for multi- than one-stemmed individuals. However, whereas multi-stemmed individuals rapidly decreased their growth rates after 60 years of age, one-stemmed trees maintained steady growth rates during the first 100 years. Depending on woodland density and tree size, total woodland biomass varied between 4000 and 15 000 kg ha⁻¹. Wood productivity was similar in all four woodlands studied (121.6-173.7 kg ha⁻¹ year⁻¹). Our results reveal the importance of tree growth habit to productivity, and suggest that regulated extraction of firewood and poles from old multi-stemmed individuals could optimize wood productivity and contribute to the sustainable use and conservation of these woodlands.     

秦皇岛市气温与近地面臭氧浓度的关系分析

利用2013年1月至2014年12月和2017年1月至2019年6月秦皇岛市近地面臭氧（O₃）浓度数据和气象资料,采用广义相加模型（GAM）,运用回归分析方法和基于R语言的统计分析软件,控制气压、相对湿度、日照时数、总云量等要素的混杂效应及时间变化趋势,分析春季、夏季、秋季、冬季气温与O₃浓度的关系。结果表明：秦皇岛市O₃浓度夏季最高、春季次之,冬季最低,与气温变化趋势基本一致,呈现明显的季节变化。各季气温与O₃浓度呈非线性相关关系,拟合曲线存在拐点,拐点两侧相关效应存在明显差异,主要表现为春季日平均气温高于15.0℃时,气温每升高1℃,O₃浓度增加7.6 μg·m^-3,增长速率是气温低于15.0℃时的4.0倍;夏季日平均气温高于27.2℃时,气温每升高1℃,O₃浓度增加13.9 μg·m^-3,增长速率是气温低于27.2℃时的11.6倍;秋季日平均气温高于21.4℃时,气温每升高1℃,O₃浓度增加47.5 μg·m^-3,增长速率是气温低于21.4℃时的19.1倍;冬季O₃浓度偏低且变化较为平稳,气温对O₃浓度的变化影响不大。由于春夏两季O₃浓度基础值偏高,因此,夏季和春季气温偏高时O₃浓度快速增加现象应引起高度重视。     

Spartina densiflora demonstrates high tolerance to phenanthrene in soil and reduces it concentration

The present study was conducted to investigate the tolerance of Spartina densiflora to phenanthrene, and to test its ability in phenanthrene dissipation. A glasshouse experiment was designed to investigate the effect of phenanthrene from 0 to 1000 mg kg⁻¹ on growth and photosynthetic apparatus of S. densiflora by measuring chlorophyll fluorescence parameters, gas exchange and photosynthetic pigments. We also performed chemical analysis of plant samples, and determined the concentration of phenanthrene remaining in soil. S. densiflora survived to concentrations as high as 1000 mg kg⁻¹ phenanthrene in soil; in fact, there was no significant difference in RGR among the treatments after 30 days. Otherwise, phenanthrene affected photosynthetic apparatus at 100 and 1000 mg kg⁻¹; thus, the lower Φ_PSII could be explained by the declined photosynthetic pigment concentrations. Soil extraction indicated a more marked rate of phenanthrene disappearance in the soil in the presence of S. densiflora.     

Timing of basin inversion on the Isle of Wight: New evidence from geophysical log correlation, seismic sections and lateral facies change in the Palaeogene Headon Hill Formation

Paleogene thickness patterns across the Bouldnor Syncline and Porchfield Anticline in the northwestern Isle of Wight have been deduced using outcrop information, borehole correlation, gamma-ray logs and seismic reflection data. The thickness patterns provide evidence for an early phase of basin inversion at around the Bartonian-Priabonian boundary (Late Eocene) in the Isle of Wight. Paleogene strata older than the Becton Sand Formation show little evidence for significant lateral changes in thickness, even though the boreholes are located at various structural positions around the Bouldnor Syncline and Porchfield Anticline. In contrast, both seismic reflection and borehole data provide evidence for marked thinning of Paleogene strata onto the Porchfield Anticline at around the level of the Becton Sand Formation and basal Headon Hill Formation (Totland Bay Member) which probably results from an episode of basin inversion and growth folding. The inversion event was relatively minor and short-lived and continues to point toward the main phase of the basin inversion being late Oligocene or younger. However, it still has important implications for understanding structural control on sedimentation patterns in the Headon Hill Formation, with the migration of sandy channelised depositional systems into the axis of the Bouldnor Syncline, and the sequence stratigraphic significance of the important Bartonian-Priabonian regression event, which may related to tectonics rather than global sea-level change.     

周期性饥饿再投喂对建鲤（Cyprinus carpio var．Jian）生长、体组成、消化酶的影响

采用周期性饥饿再投喂的方法,研究周期性饥饿再投喂对建鲤（1．5±0．2g）的生长、体组成、消化酶的影响。试验分为10个组,共进行60d。结果表明,在相同的饥饿天数下,延长再投喂天数可以使建鲤的增重率逐渐增加,而且S1F4、S2F8、S4F16组的增重率与对照组无显著性差异（P〉0．05）,9个周期性饥饿再投喂组在摄食期...     

Contrasting shell morphology, ingestion and grazing preferences in the neritid gastropod Smaragdia viridis (L.) on two seagrass species

The neritid Smaragdia viridis represents the only known native marine mollusc that feeds on seagrass tissues in the European coasts, displaying a strong association with the seagrasses Cymodocea nodosa and Zostera marina in southern Spain. Seasonal dynamics, shell and radular morphology, growth and feeding of this gastropod have been studied in relation to each seagrass species for contrasting trends resulting from a different type of substrate and food source. In both seagrass species, stable populations of this gastropod occur at similar densities and displaying similar growth rates. Nevertheless shells of individuals from C. nodosa are narrower than those from Z. marina and some differences, possibly a consequence of increased wearing on C. nodosa, were noted amongst the radulae. In C. nodosa, a pre-ingestive selection for young epidermal tissues occurs as it was previously observed in Z. marina. The ingestion rate is higher in C. nodosa than in Z. marina but the absorption of ingested tissues is lower in the former. If both seagrasses are present, most individuals ingested preferentially Z. marina rather than C. nodosa, probably due to the lower digestibility of the epidermal tissues in the latter. Seagrass beds, especially those of Z. marina, are suffering a strong regression in southern Spain and the presence of stable populations of this neritid may be restricted to other declining seagrass species in the area.     

冰晶增长对热量收支的影响

使用二维云分辨模式研究冰晶增长过程(云水到冰晶的冻结增长和通过水汽凝华冰晶到雪的增长)对热量收支的影响。采用4种冰晶增长参数化方案模拟了热带到中纬度地区的4个降水个例。研究发现:(1)高冰核浓度的ZENG方案和SHEN方案引起对流层中上层辐射加热增多,这与它们模拟的冰晶在对流层中上层增多有关。(2)高冰核浓度的ZENG方案导致模拟区域—平均的局地温度变化在对流层上层出现异常减小值,这与它在热带个例中导致垂直热量通量辐合减少和在中纬度个例中导致潜热加热减少有关。(3)尽管高冰核浓度的ZENG方案引起质量加权平均的辐射加热增多,但是它在热带个例中引起地表感热通量减少和在中纬度个例中引起潜热加热减少,最终导致4种参数化方案计算的模拟区域—质量加权平均的局地温度变化基本一致。     

1992—2012年东北水稻生育期变化分析

生产实践中水稻生育期变化是气候条件和品种更新等因素共同作用的结果。利用东北地区13个农业气象站点1992—2012年水稻试验观测资料,分析水稻生育期的变化及其与东北变暖趋势、水稻品种调整的关系。结果表明：水稻生长季平均气温和≥10℃积温在1992—2001年呈显著增加趋势,水稻生长季积温的差别最大可达500℃?d,从2002年开始升温趋势减缓,并略有下降。相应地,2002—2012年与1992—2001年的物候期基本上呈现相反的变化特征,其中抽穗期、乳熟期、成熟期在1992—2001年明显提前,分别提前了3.1、2.9、4.5 d/10a,移栽期、分蘖期、成熟期则在2002—2012年呈现出明显的推迟趋势,分别推迟了4.6、4.7、2.0 d/10a;生育期的变化受多种因素影响,但播种-移栽期、乳熟-成熟期在1992—2001年分别缩短了0.7、1.6 d/10a,而在2002—2012年则分别延长了2.9、2.8 d/10a;总的来说,1992—2012年水稻全生育期整体延长了3.7 d/10a,其主要归因于营养生长期的延长。在试验资料比较完整的12个站点所做的分析表明,在东北水稻种植的生产实践中,不断地通过品种调整适应气候条件的改变,多数站点水稻实际生育期与品种审定生育日数差别较小,说明其品种的选择能够与当年的气候条件较好地匹配,充分利用了当地的气候资源。延吉站、梅河口站、通化站随着气候的持续波动又显示出水稻实际生育期与品种审定生育日数偏差增大的趋势,宁安站和前郭尔罗斯站的水稻种植品种的审定生育日数几乎没有改变。因此,迫切需要对东北气候变化的科学事实和水稻种植适应气候变化的生产实践进行系统的总结,为东北水稻生产适应气候变化提供科学支撑。     

“双评价”视角下基于FLUS模型的武汉大都市区土地利用模拟和城镇开发边界划定研究

城镇开发边界的划定对于保障资源合理利用、促进城镇有序发展具有重要意义。国内现有研究多以规划实践的技术探讨为主,但对资源环境的定量化评估不足,且较少在大都市区尺度开展研究。本文以武汉大都市区为研究案例,提出在耦合多种要素构建“双评价”体系的基础上,结合FLUS模型进行土地利用模拟和城镇开发边界的划定,并运用景观格局指数等对结果进行分析校验。结果表明:① 土地利用模拟KAPPA系数为0.95,总体精度为0.96,能较好的反映未来用地变化情况,且结果显示城镇建设用地呈蔓延式扩张,有必要通过划定边界来控制城镇开发;② 根据模拟结果划定城镇开发边界,能够避免城镇建设集中占用生态或农业价值较高的区域,并在优化形态的基础上改善武汉大都市区的城镇空间布局,有很强的适用性;③ 驱动体系评价表明,相较于单一因子库,“双评价”因子库精度更高,且更能优化景观格局,促进建设用地斑块集聚发展并填补建成区空白,更符合区域发展诉求;④ 扩张结果评价表明划定结果与武汉大都市区的未来发展模式吻合,未来空间管控应重点关注临空港片区、阳逻片区、光谷-未来城片区、纸坊片区扩张的潜在价值。本研究验证了FLUS模型在武汉大都市区内应用的有效性,为规划管控及建设用地布局优化提供一定参考。     

4种微量金属元素对绿色巴夫藻生长、叶绿素a及大小的影响

把 4种微量金属离子以不同的浓度添加到绿色巴夫藻的培养液中 ,结果表明 :Hg2 +和Pb2 +浓度分别在 5μg/L和 2 0 0 μg/L时 ,对绿色巴夫藻的生长有较好的促进作用 ,同时也使叶绿素a的含量提高 ;Hg2 +≥ 2 0 μg/L时 ,绿色巴夫藻的生长受到抑制 ,叶绿素a的含量降低。Pb2 +所有的试验浓度都使绿色巴夫藻生长加快 ,叶绿素a的含量提高 ;Co2 +在 1μg/L时对绿色巴夫藻的生长有最好的促进效果 ,但当Co2 +≥ 5μg/L时 ,开始对生长出现抑制作用 ,而Co2 +所有的试验浓度都使叶绿素a的含量降低 ;Mn2 +浓度在 10 0 μg/L时 ,对促进绿色巴夫藻生长的效果最佳 ,4 0 0 μg/L的浓度开始对生长出现抑制作用 ,但所有Mn2 +的试验浓度对叶绿素a含量的变化影响不显著。 4种微量金属元素都使绿色巴夫藻略微变小。