It is necessary to study the characteristics of the spatial and temporal characteristics and influencing factors of carbon emissions. Doing so holds great significance for optimizing urban spatial patterns and protecting the environment. Based on the ArcGIS and SPSS packages and Pearson correlation coefficient analysis, this study analyzed the carbon emission data, population data, gross domestic product (GDP) data and land use data of 19 districts and counties in Chengdu in 2000, 2005, 2010 and 2015. Based on the analysis, the characteristics of the temporal and spatial distribution and influencing factors of carbon emissions in Chengdu are discussed. We hope to provide a relevant basis for future urban construction and policy making in Chengdu. The research results show that the overall carbon emissions in Chengdu are increasing. Since 2010, the carbon emissions in the central city began to decrease, while the carbon emissions in other major carbon emission areas grew relatively slowly. Population, the economy and land use will affect carbon emissions in Chengdu.

Mixing with different broadleaf trees into the monocultures of Cunninghamia lanceolata is widely adopted as an efficient transformation of the pure C. lanceolata forest. However, it is unclear how native broad-leaved trees influence the belowground ecological environment of the pure C. lanceolata culture plantation in nutrient-poor soil of South China. Herein, we aimed to investigate how a long-time mixing with native broadleaf trees shape soil microbial community of the pure C. lanceolata forest across different soil depth (0-20 cm and 20-40 cm) and to clarify relationships between the modified soil microbial community and those affected soil chemical properties. Using high-throughput sequencing technology, microbial compositions from the mixed C. lanceolata-broadleaf forest and the pure C. lanceolata forest were analyzed. Network analysis was utilized to investigate correlations among microorganisms, and network robustness was assessed by calculating network natural connectivity. Results demonstrated that the content of soil microbial biomass carbon and nitrogen, total phosphorus and pH in mixed forest stand were significantly higher than those in pure forest stand, except for available phosphorus in topsoil (0-20 cm). Simultaneously, the mixed C. lanceolata-broadleaf forest has a more homogeneous bacterial and fungal communities across different soil depth compared with the pure C. lanceolata forest, wherein the mixed forest recruited more diverse bacterial community in subsoil (20-40 cm) and reduced the diversity of fungal community in topsoil. Meanwhile, the mixed forest showed higher bacterial community stability while the pure forest showed higher fungal community stability. Moreover, bacterial communities showed significant correlations with various soil chemical indicators, whereas fungal communities exhibited correlations with only TP and pH. Therefore, the mixed C. lanceolata-broadleaf forest rely on their recruiting bacterial community to enhance and maintain the higher nutrient status of soil while the pure C. lanceolata forest rely on some specific fungi to satisfy their phosphorus requirement for survive strategy.

为探究广州市常见园林植物夏季光合特性及其固碳释氧能力,以广州市园林9种典型园林树种幼苗为研究材料,采用Li-Cor6400便携式光合测定仪测定光合参数特征和光响应曲线,计算各苗木的日固碳释氧能力,分析光合速率影响因素,并以单位绿化面积固碳量作为衡量各树种苗木吸收CO2能力的特征向量进行聚类分析.结果表明:9种的园林树种幼苗单位叶面积固碳量和释氧量分别为6.25～11.93、4.55～8.68 g·m-2·d-1,单位绿化面积固碳量和释氧量分别为1.87～10.37、1.33～7.54 g·m-2·d-1,9个园林树种苗木的光合净固碳量按高低排序可分为3类,单株植物单位绿化面积固碳量较高(9.44～10.37 g·m-2·d-1)的有铁冬青Ilex rotunda、枫香Liquidambar formosana、假苹婆Sterculia lanceolata、糖胶树Alstonia scholaris,中等(7.19～8.38 g·m-2·d-1)的有仪花Lysidice rhodostegia、樟树Cinnamomum camphora,较低(1.87～5.89 g·m-2·d-1)的有杧果Mangifera indica、木油桐Aleurites montana、鱼尾葵Caryota ochlandra.综合考虑植物的光合及固碳特性,在树种配置时,枫香、糖胶树、假苹婆和铁冬青为优选乔木树种.

人为干扰已经成为影响自然保护区自然生态系统的最主要的干扰因素之一.在广东云开山国家级自然保护区选取数量多、影响范围广的受种植、道路、风电以及坟墓等4个干扰类型的土壤为研究对象,研究人为干扰下土壤环境的变化,测定其土壤理化性质特征.结果表明:土壤毛管持水量和毛管持水率呈正相关性,坟墓干扰下样地的毛管持水性最好;土壤总孔隙度变动与土壤容重变动呈现反比例关系.坟墓干扰下的环境土壤稀松、结构性较好,风电干扰下的环境土壤结构性较差,土壤持水性表现较差.全氮和碱解氮这两个指标呈现出一致的趋势,两者总体表现为对照点>干扰点,其中坟墓干扰>种植干扰>风电干扰>道路干扰.有效磷与全磷指标表现出正相关规律,但规律不显著,其中对照点>干扰点.

为了解不同疏伐处理下的荔枝林Litchi chinensis林分改造树种生长差异,采用全砍、回缩、修剪、保留 4 种不同疏伐处理,并套种黧蒴Castanopsis fissa等 9 个乡土阔叶树种,对撂荒荔枝林进行林分改造,分析改造后树种的生长及植物多样性表现,对改造 6 年后树种生长差异进行分析.结果表明:不同疏伐处理以及不同套种方式下改造树种的平均树高、冠幅生长量和胸径生长量均存在差异.其中,修剪套种处理对林分、荔枝个体和套种树种的生长量促进作用最为明显,回缩套种处理次之,全砍套种和回缩套种处理生长量较低.对植物多样性进行分析,发现 4 种改造类型均不同程度地提高了灌木层和草本层植物多样性,说明适当的回缩或修剪有利于草本和灌木的迁入和定居.总体来看,修剪套种和回缩套种方式有最利于改造树种的生长以及植物丰富度的增加.

在东莞燕岭湿地公园选择6 种植物群落,调查其植物组成、枯落物层以及土壤层的持水特性.结果表明:样地植物共有72 种,隶属于45 科64 属;6 种植物群落的乔灌草各层基本上均由3 种植物组成;落羽杉Taxodium distichum群落种植密度最大;各样地枯落物的蓄积量无显著差异,银合欢Leucaena leucocephala群落和黄槐决明Cassia surattensis+红花羊蹄甲Bauhinia blakeana群落枯落物对降水的拦蓄能力最好.黄槐决明+木棉Bombax ceiba群落的土壤容重最大;黄槐决明+红花羊蹄甲和黄槐决明+木棉群落的土壤贮水能力较强;水黄皮Pongamia pinnata群落土壤吸收、贮存降水的能力较强;黄槐决明+木棉群落涵养水源效果较好.

The responses of Cinnamomum camphora and Michelia chapensis to ozone (O-3) exposure in terms of the O-3 injury and changes in the physiological parameters of their leaves were examined in charcoal-filtered (CF) air and O-3 at 1x, 2x, and 4xO(3) ambient concentrations in open-top chambers in an eight-month experimental period. High levels of O-3 exposure led to visible injuries in both species. The increased chlorophyll content in the second month and increased carotenoid content of the 1xO(3) treatment group at the end of experiment were identified as hormetic-compensatory strategies that enhance tolerance and acclimation to O-3 stress. Significant interaction effect between O(3)and tree species with respect to the superoxide dismutase (SOD) activity and proline content suggests that the effects induced by O-3 were highly dependent on the tree species. C. camphora showed more foliar injury symptoms and greater O-3-induced decreases in the chlorophyll, carotenoid, and protein contents than M. chapensis, which suggests that C. camphora is more sensitive to O-3 than M. chapensis.

以杜鹃红山茶Camellia azalea、山茶C.japonica和金花茶C.petelotii3种山茶科植物苗木为试验对象,测定其叶片光合特性参数和叶绿素荧光参数.结果表明:3种山茶科植物光合特性参数差异显著,其中光合速率强弱表现为山茶(4.574μmol·m-2 s-1)>杜鹃红山茶(1.881μmol·m-2 s-1)>金花茶(0.855μmol·m-2 s-1),蒸腾速率强弱表现为山茶(1.774 mmol·m-2 s-1)>杜鹃红山茶(0.608 mmol·m-2 s-1)>金花茶(0.339 mmol·m-2 s-1),气孔导度强弱表现为山茶(0.060 mmol·m-2 s-1)>杜鹃红山茶(0.020 mmol·m-2 s-1)>金花茶(0.010 mmol·m-2 s-1),光能利用率强弱表现为山茶(0.005μmol·mmol-1)>杜鹃红山茶(0.002μmol·mmol-1)>金花茶(0.001μmol·mmol-1).3种山茶科植物叶绿素荧光参数差异显著,其中光下最大荧光产量强弱表现为杜鹃红山茶(1.825)>金花茶(1.611)>山茶(1.442),PSⅡ实际光量子效率强弱表现为山茶(0.095)>金花茶(0.070)>杜鹃红山茶(0.067),表观电子传递速率强弱表现为山茶(7.551)>金花茶(5.697)>杜鹃红山茶(5.477).总体上看,光合能力山茶>杜鹃红山茶>金花茶.

阳春市有着丰富的古树名木资源,通过调查统计,阳春市古树名木共有1675株,隶属于35科69属96种,其中,大戟科、豆科、樟科为优势科.分析了阳春市古树名木的种类与数量、分布特征、生长及环境特征和古树群落分布特征.结果 表明:从分布特征看,生长在乡村的古树为1608株,其数量是生长在城区的24倍,占建档古树名木总株数的96.00％;从生长特征可知,生长势正常的古树有1644株,占建档古树名木总株数的98.15％,衰弱级、濒危级和死亡级古树仅占建档古树名木总株数的1.85％;从生长环境状况来看,1675株古树中生长环境好的有1615株,整体古树生长环境较好;从古树群落分布现状来看,最具代表性的古树群落为古红锥Castanopsis hystrix群落和古荔枝Litchi chinensis群落.总体而言,阳春市古树名木生长环境较好,保存得较完整,可以更好地实施下一步保护措施.

工业、农业和交通等来源引起的土壤重金属污染问题日益突出,土壤环境质量形势严峻,污染土壤的生态修复与治理已然成为亟待解决的科学问题.植物修复技术是修复重金属污染土壤的一种有效途径.基于园林植物对重金属元素的富集和吸收作用,植物修复技术具有经济、生态、环保、对环境破坏力度小、美化环境等优势,已成为众多学者关注的研究热点.文章通过查阅文献资料,对近年园林植物修复重金属污染土壤领域的研究成果进行了梳理与阐述,从园林植物修复土壤重金属的技术、重金属富集园林植物的筛选、植物修复技术的联合应用等方面进行了总结归纳和分析,同时对植物修复土壤重金属污染的发展前景进行了展望.

文章以南澳岛17种典型林分作为研究对象,采用环刀法分别对17种样地进行调查取样,分析比较其土壤的理化特性.结果表明:(1)17种林分中,台湾相思Acacia confusa和柠檬桉Eucalyptus citriodora混交林土壤容重最高,达到1.32 g·cm-3,而最低为台湾相思和鸭脚木Schefflera octophylla混交林,为0.68 g·cm-3.(2)17种林分中,白鹭生态公园相思纯林土壤毛管持水量最高,达到643.17 g·kg-1,最低则为216.26 g·kg-1,为台湾相思和尾叶桉Eucalyptus urophylla混交林.(3)17种林分土壤总孔隙度在46.33％～74.04％之间.(4)土壤有机质含量最高的为枫香Liquidambar formosana纯林,为42.86 g·kg-1,最低是马尾松Pinus massoniana和其它阔叶树混交林,含量只有7.71 g·kg-1.总体而言,台湾相思和鸭脚木混交林土壤疏松,结构性较好,而白鹭生态公园相思纯林土壤物理特性最好,枫香纯林土壤化学特性最好.因此,应加强对混交林的保护及抚育,提高林分质量.

Airborne bacteria play important roles in air pollution, human health and biogeochemical cycles. However, their spatial variation and determinant factors in forest environments are poorly understood. In this study, we selected five forest types in the Liuxihe National Park, South China, to analyze how near-surface bacterial community structure is related to the forest community structure and soil physicochemical properties. The results indicated that the dominant communities were mainly constituted by seven bacterial genera of the phyla Proteobacteria (49.7%–55.4%) and Firmicutes (44.2%–49.8%), including Exiguobacterium (42.0%–46.4%), Citrobacter (20.7%–25.8%), Acinetobacter (20.1%–22.1%), and Pseudomonas (7.8%–8.9%) etc. However, differences in the composition and diversity of the airborne bacterial communities were evident among the five forests, especially with respect to the dominant taxa. The relative abundance of Enterococcus and Bacillus in coniferous and broad-leaved mixed forest (MF), broad-leaved mixed forest (BF), and pure Cunninghamia lanceolata forest (CL) was significantly higher than that of the other forests, while the relative abundance of Citrobacter was significantly lower. The relative abundance of Citrobacter, Acinetobacter, and Pseudomonas in Proteobacteria were significantly negatively correlated with plant diversity and acid phosphatase activity but positively correlated with soil pH and soil available potassium. Contrastingly, the correlation between the relative abundance of most genera of Firmicutes and the above environmental factors is just the opposite of that for Proteobacteria. We provide direct evidence that native plant communities in the middle stage of succession, compared to planted forests and forest open space, generally had higher airborne bacterial diversity. Airborne bacterial diversity showed a significantly positive correlation with plant diversity (p < 0.05). Over all, soil pH, soil available potassium, and soil available phosphorus contributed to a high rate of the diversity of the airborne bacterial community in near-surface, followed by the plant diversity of the arbor layer and the near-surface air temperature. These results extended our understanding of the ecological patterns of airborne bacteria in forest ecosystems.

The increasing concentration of surface ozone (O3) was observed during recent decades in the world, which affects tree roots and forest soils. Meanwhile, the impact of ozone on tree roots is greatly affected by soil condition. However, there is a lack of knowledge about the possible effects of ozone on tree roots and soil processes. In this study, The influences of surface ozone (O3) stress on the root biomass, morphology, nutrients, soil properties, and soil enzyme activity of Elaeocarpus sylvestris and Michelia chapensis seedlings were examined at four O3 concentrations (charcoal-filtered air, 1 × O3 air, 2 × O3 air, and 4 × O3 air). Elevated O3 concentrations were found to significantly increase the root C content, N content, C/P ratio, and N/P ratio, and significantly decrease the root biomass, number of root tips, and root C/N ratio of both species. The soil organic matter content, pH, total N content, and urease and catalase activities of both species tended to increase. The limitation in root growth and responses in the root structure of E. sylvestris induced by elevated O3 concentrations led to increased bulk density and decreased soil porosity and void ratio. These profound effects of O3 concentrations on the roots and soil characteristics of these two species underscore the importance of research in O3 science.

为探究树种的防火能力,科学选择防火林带树种,提高生物防火林带的树种多样性,对28种防火林带树种的理化指标进行测定,应用因子分析和聚类分析方法对其抗火性能进行综合排序与分类.结果表明,树叶热值与灰分、挥发分与固定碳之间呈极显著相关关系,热值与挥发分之间、灰分与挥发分之间呈显著相关关系;综合排序表明鸭脚木、夹竹桃、米老排、大叶相思、深山含笑、黧蒴、木荷、红花油茶、铁冬青、台湾相思、醉香含笑、凤凰木为抗火性较好的12个树种.聚类分析结果表明,抗火性强的树种有4种,夹竹桃、鸭脚木、大叶相思、铁冬青;抗火性较强的树种有7种,黧蒴、米老排、醉香含笑、台湾相思、深山含笑、木荷、山杜英;抗火性中等的树种有6种,西南木荷、乌桕、凤凰木、红花油茶、土沉香、樟树;抗火性较弱的树种有8种,枫香、柠檬桉、黄葛榕、马占相思、观光木、红苞木、红锥、山乌桕;抗火性弱的树种有3种,多花山竹子、蝴蝶果、假苹婆.

以马尾松(Pinus massoniana)与乡土树种黧蒴(Castanopsis fissa)、红锥(Castanopsis hystrix)、枫香(Liquidambar formosana)、荷木(Schima superba)和假苹婆(Sterculia lanceolata为研究对象设计混交盆栽试验,研究叶片光合和全株光合特征参数的差异.结果 表明:枫香对马尾松、黧蒴的光合作用有一定的促进作用,各树种的光合能力基本表现为从对照组到单混种组到双混种组依次上升的变化趋势.双混种组合的实际光合能力相比理论值平均提高15.62％.马尾松+黧蒴+枫香组合的光合作用提升程度最大,是本次试验的最佳组合.

The influences of elevated ozone (O-3) concentrations on biomass, leaf gas exchange, fluorescence parameters, and leaf physiological and biochemical traits were examined in Elaeocarpus sylvestris and Michelia chapensis seedlings under four O-3 conditions for a growing season in open-top chambers (OTCs). The four O-3 concentrations were charcoal-filtered air (CF) (20 ppb), 1 x O-3 air (40 ppb), 2 x O-3 air (80 ppb), and 4 x O-3 air (160 ppb), respectively. The significant decrease in the root/shoot (R/S) ratios of both species indicated that under O-3 stress root biomass was more negatively affected than shoot biomass for both tree seedlings. Along with the loss of chlorophyll and carotenoid contents, decrease in the superoxide dismutase (SOD), and enhanced level of lipid peroxidant, the light-saturated net photosynthesis rate (P-nmax) of E. sylvestris, the effective quantum yield of PSII photochemistry (Y(II)) and the electron transport rate (ETR) of both species decreased, suggesting that impaired photosynthesis occurred. The negative effect of O-3 on physiological and biochemical parameters was greater for M. chapensis than for E. sylvestris. As the O-3 concentration increased, the leaf mass per area (LMA) of E. sylvestris decreased, while that of M. chapensis increased. Therefore, the increased SOD activity as a hormetic-compensatory response, the increases in LMA and longer vegetative period contributed to the good adaptability and high tolerance of M. chapensis.

以马尾松Pinus massoniana与乡土树种荷木Schima superba、黧蒴Castanopsis fissa、红锥Castanopsis hystrix、枫香Liquidambar formosana和假苹婆Sterculia lanceolata为研究对象进行混交试验,研究苗木叶片超微弱发光特征的差异.结果表明,各树种的超微弱发光特征值大小总体表现为对照组<单混种组<双混种组,各树种混种后树种的超微弱发光特征值均有不同程度提高,所有组合中,马尾松+黧蒴+枫香组合超微弱发光特征值最高.从聚类分析结果来看,马尾松+黧蒴+荷木、马尾松+枫香+荷木、马尾松+红锥+荷木、马尾松+红锥+黧蒴以及马尾松+红锥+枫香等组合,各树种内部相互联系程度高,代谢旺盛,树种组合抗性好,生命力强,是马尾松纯林林分改造的理想树种搭配选择.

大学生亚健康问题是高等教育关注的焦点问题,学生心理和生理的健康状况是高校良好教学质量和水平的重要保障.针对当前大学生普遍存在的亚健康问题,以华南农业大学非农专业学生为研究对象,分析大学生的情绪症状现状,以提高学生身心健康状况和综合实践能力为目标,整合观赏植物认知、园艺种植实操、课前课后体验评价三大模块,提出围绕园艺疗法理念的农事训练实践教学体系,从实践教学层面提高大学生身体素质和健康水平,为提高高校实践训练教学水平提供参考.

基于珠三角洲气候灾害频发的大背景,通过综合分析国内外红树林湿地及其生态系统的相关研究成果,主要讨论了极端气候对其产生的消极影响,同时探讨了其对气候因子的响应途径与机制,旨在对珠三角区域红树林在极端气候事件作用下,为进一步量化其景观格局动态变化与干扰因子间关系的研究建立基础.

以花叶鹅掌柴、龙船花、白蟾、狗牙花、软枝黄蝉和红背桂6种园林灌木为材料,研究人工模拟干旱胁迫环境对植物光合指标和叶绿素荧光动力参数的影响,结合主成分分析法综合评价其抗旱能力.结果 表明,(1)干旱胁迫处理期间,6种灌木的净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)、和蒸腾速率(Tr)持续下降,复水后软枝黄蝉的Ci未能得到有效恢复,其余植物各光合指标均有回升.(2)光合系统Ⅱ(PSⅡ)的有效光化学量子产量(Fv'/Fm')、实际光化学量子效率[Y(Ⅱ)]、表观光合电子传递速率(ETR)、光化学淬灭(qP)随着胁迫强度加重而降低,复水后各项指标均有所恢复,其中花叶鹅掌柴的Y(Ⅱ)、ETR和qP、毛杜鹃的Fv'/Fm'和Y(Ⅱ)、龙船花和红背桂的Fv'/Fm'、狗牙花的ETR均恢复至对照水平.6种灌木的非光化学淬灭(NPQ)持续上升,复水后白蟾有所下降,但仍显著高于对照,其余植物均恢复到对照水平.(3)主成分分析结果表明,6种园林灌木的抗旱性强弱顺序为花叶鹅掌柴＞白蟾＞狗牙花＞红背桂＞软枝黄蝉＞龙船花.