Local variation of outdoor thermal comfort in different urban green spaces in Guangzhou,a subtropical city in South China

To understand the influence of different urban green spaces on outdoor thermal comfort, researchers have focused on developing a thermal comfort range and estimating neutral and preferred temperatures through questionnaire surveys and microclimatic measurements. The simultaneity of investigation among different sites is often neglected, which decreases the accuracy and reliability of the outcomes. To fill this gap and to better address the local variation of outdoor thermal comfort in different urban green spaces, both surveys and measurements were performed simultaneously at three sites, “central grassland,” “pond-side garden” and “grove” in a subtropical urban local area in warm and cool periods. Remarkable differences in microclimatic conditions, thermal sensations, thermal comfort, and both neutral temperatures and preferred temperatures were observed among the three sites and in the two periods. Preferred temperatures were lower than neutral temperatures among different sites in each period or both periods combined, indicating the instinctive preference of people from relatively hot regions for a cooler thermal state. The grove yielded the best cooling capability but was perceived as the hottest and most uncomfortable site in the warm period. The central grassland with the highest air temperature, conversely, was perceived as the most comfortable site. The subjective perceptions were also reflected by lower neutral and preferred temperatures in the grove than those in the central grassland in the warm period. In particular, for preferred temperatures, up to 8.8 °C operative temperature (T_op) and 4.3 °C physiological equivalent temperature (PET) differences between these two sites were observed. Hence, a high density of trees does not necessarily result in better outdoor thermal comfort. Future urban planning and management, therefore, should emphasize the types and structures of different urban green spaces. To further comprehensively explore the roles of different urban green spaces in outdoor thermal comfort, high synchronicity among sites during investigation is important.     

Interactions of grazing and rainfall on vegetation at Grootfontein in the eastern Karoo§

Rainfall and grazing are primary drivers of vegetation composition in the Nama-Karoo. Increased rainfall increases grassiness, to where Nama-Karoo transitions to grassland. Severe grazing treatments (e.g. continuous or summer-only) increase abundance of grazing-tolerant dwarf shrubs and annual grasses, and decrease perennial grasses. Grootfontein, which is ecotonal between the Nama-Karoo and Grassland Biomes, houses long-term grazing trials. The area has experienced higher-than-average rainfall in recent decades. Plant basal cover data from the 1960s and 2010s allow several hypotheses to be addressed: (1) historical severe grazing (until 1985) will limit subsequent grassiness (grazing legacy effect); (2) severe grazing will preclude increases in grassiness, independent of rainfall (herbivore trap effect); and (3) historically leniently-grazed sites will transition to grassland with increased rainfall (biome shift effect). Rainfall was lower from 1957–1966 (350 mm) than from 2003–2012 (490 mm). The grazing legacy effect was supported based on the abundance of Aristida diffusa, despite all sites becoming much grassier. The herbivore trap effect was not supported. The biome shift effect was supported in that shifts to grassland sometimes occurred. Results suggest that increasing rainfall has prompted a shift to much increased grassiness and decreased abundance of dwarf shrubs, and that grazing had a smaller secondary effect.     

2012年7月9日临朐地区暴雨成因及漏报原因分析

为了更好地研究潍坊市暴雨落区,减少暴雨灾害发生,为以后的暴雨预报工作总结经验,提高预报准确率,特对2012年7月9日临朐地区暴雨过程进行诊断分析。利用气象信息综合分析处理系统 MICAPS 3.1,对常规气象资料进行剖面分析、探空分析,最后对数值预报产品进行检验,得出暴雨的产生和漏报原因。结果表明,此次暴雨产生的重要原因是中纬度短波槽带来的干冷空气与低空急流带来西南暖湿气流的叠加,同时临朐县南部沂山造成的地形影响和弥河的水汽蒸发也是其中重要原因。漏报的主要原因是由于过分依赖数值产品的降水预报和忽略中小尺度系统的演变以及对物理量场分析不深入。通过总结分析得出结论,要做好暴雨的预报必须综合考虑天气实况,重点分析各物理量,同时加强预报员对数值预报产品的订正工作。     

10种亚热带植物冻害调查与分析

在城市风貌塑造过程中,必然要求丰富而多样的园林植物,而低温是限制园林植物引种的核心因子,也是影响园林植物生长的气象灾害因子之一。2016年冬春四川省绵阳市遭遇了40年一遇的霸王级寒潮,引种的亚热带植物受冻害严重。调查与分析了该市10种亚热带植物的冻害情况,并提出挽救与防寒措施指出园林绿化中必须坚持科学引种、适地适树的基本原则。     

亚热带4种典型森林植被土壤固碳细菌群落结构及数量特征

为研究亚热带不同森林植被类型土壤固碳微生物特征及其影响因子,选取毛竹林(Moso banboo groves)、阔叶林(Broad-leaved forest)、杉木林(Chinese fir forest)和马尾松林(Masson pine forest)等4种森林植被为研究对象,以 cbbL为固碳细菌指示基因,利用实时荧光定量PCR (Real-time quantitative PCR)和MiSeq高通量测序为研究手段。结果表明,4种林分土壤的细菌16S rRNA基因和固碳细菌cbbL基因丰度范围分别是5.40×10~(10)～2.81×10~(11) copies·g~(-1)干土和4.55×10~8～3.53×10~9 copies·g~(-1)干土,其中毛竹林显著高于其他三种林分(P0.05);基因丰度显著关联的环境因子是阔叶林土壤的有效磷、不同土层的pH(P0.05)。杉木林土壤固碳细菌多样性显著低于其他3种林分(P0.05),其亚表层土壤高于表层(P0.05);双因子分析表明,林型、土层之间土壤固碳细菌多样性均存在显著或极显著差异。所有土壤具有相似的优势属但相对丰度不同,其中毛竹林和杉木林土壤的甲基化石油杆菌属(Methylibium)和诺卡菌属(Nocardia)占比明显高于阔叶林和马尾松林。冗余分析结果显示,不同林分土壤pH、土壤有机碳、有效磷、全氮差异是影响土壤固碳细菌群落特征形成的主要因素。综上,4种植被对土壤固碳微生物数量及群落结构多样性影响明显,从土壤理化性质、固碳细菌基因丰度、多样性以及结构特征等多维度结果证明,毛竹林对土壤肥力以及固碳细菌影响效果最好,固碳微生物对毛竹林土壤有机质积累贡献大于阔叶林,定量结论有待进一步研究。     

福建亚热带果园土壤pH值与有效态养分含量的相关性

福建亚热带果园土壤ｐＨ值与有效态养分含量关系密切。其中，柑桔、龙眼园的两者相关性表现较好，而荔枝园的相关性表现较差。相关关系回归方程的最佳函数类型因元素不同而异。ｐＨ值与代换态锰含量的关系符合幂函数方程；ｐＨ值与交换态钙、有效态铁含量的关系较符合指数函数方程；ｐＨ值与交换态镁、有效态锌含量的关系较符合线性函数方程。回归分析表明，果园土壤ｐＨ值小于５．００或大于６．５０时，土壤有效态养分含量变化较大（尤其是代换态锰、交换态钙和有效态铁、铜）。柑桔园及龙眼、荔枝园土壤ｐＨ值的最适范围分别为５．００～６．５０和５．５０～６．５０。     

Dynamics of fine and coarse roots and nitrogen mineralization in a humid subtropical forest ecosystem of northeast India

The present study was carried out to understand whether fine root growth and N mineralization are synchronized in such a manner that helps to conserve N in the humid subtropical forest ecosystem, and to assess whether or not these processes are influenced by human disturbance. The study was conducted in two pairs of undisturbed and disturbed stands of subtropical humid forest in the Jaintia hill district of Meghalaya, northeast India. The amount of fine root (540–754 g m^–2) and coarse root (307–387 g m^–2) mass in the protected stands was higher than those recorded (fine root 422–466 g m^–2, coarse root 247–305 g m^–2) in the unprotected stands. The total annual root production was also higher in the protected stands (1,102–1,242 g m^–2) than the unprotected stands (890–940 g m^–2). The mean concentration of NH₄⁺–N and NO₃^––N was higher in the protected stands than in the unprotected stands. The inorganic-N (NH₄⁺–N and NO₃^––N) concentration was markedly high during the dry period and low during the wet period in all the stands. Inorganic-N concentration, nitrification and N mineralization rates were significantly (P<0.01) higher in the surface (0–10 cm) than the subsurface (10–20 cm) layer. The low and high N mineralization rates observed during the dry and wet periods, respectively, coincided with the lean and peak periods of fine root mass. Disturbance in the forests caused a reduction in fine root mass as well as in N mineralization.     

西太平洋副高演变特征与华南旱涝的关系

通过对1951～2000年西太平洋副高4个特征指数的分析发现,年际尺度上西太平洋副高面积和强度指数有3.5年周期,北界指数有2.6年和5年周期,这和华南降水及其异常变化趋势一致,说明西太平洋副高是影响华南降水最主要因素之一。物理量诊断分析表明,西太平洋副高主要是通过500hPa涡度和850hPa散度和水气通量散度的显著变化来影响华南降水异常分布的。     

《亚热带水土保持》性质及学科分类

根据期刊性质和学科分类方法,以文献数量对《亚热带水土保持》进行分类。结果表明,《亚热带水土保持》2010年刊登的论文以学术性为主,农业基础科学类、农艺学类文献分别占当年文献总量的53.70%和50.93%,其余学科文献量较少,不能划入相应学科,因此应将该刊同时归类为农业基础科学类和农艺学类专业学术期刊。     

Estimating interrill soil erosion from aggregate stability of Ultisols in subtropical China

During raindrop impact soil, aggregates breakdown and produce finer, more transportable particles and micro-aggregates. These particles and micro-aggregates appreciably affect the processes of infiltration, seal and crust development, runoff, and soil erosion. Aggregate stability is, therefore, an important property that may explain, quantify, and predict these processes. This study was designed to develop improved formulae for assessing interrill erosion rate by incorporating the aggregate stability index (A_s) in the prediction evaluations for soil erodibilites of Ultisols in subtropical China. Field experiments of simulated rainfall involving rainstorm simulations with medium and high rainfall intensity were conducted on six cultivated soils for which the soil aggregate stability was determined by the LB-method. This study yielded two prediction equations D_i = 0.23A_sI²(1.05 − 0.85 exp^−4sin θ) and D_i = 0.34A_sqI(1.05 − 0.85 exp^−4sin θ) that allowed a comparison of their efficiency in assessing the interrill erosion rate. A_s is an aggregate stability index, which reflected the main mechanisms of aggregate breakdown in interrill erosion process, θ is the slope angle, I is the rainfall intensity, and q is the runoff rate. Relatively good agreement was obtained between predicted and measured values of erosion rates for each of the prediction models (R² = 0.86^**, and R² = 0.90^**). It was concluded that these formulae based on the stability index, A_s, have the potential to improve methodology for assessing interrill erosion rates for the subtropical Chinese Ultisols. Considering the time-consuming and costly experimentation of runoff rate measurements, the equation without runoff rate (q) was the more convenient and effective one to predict interrill erosion rates on Ultisols of subtropical China.