IAP大气-植被耦合模式的建立及其模拟

为了充分理解气候与植被之间在不同时间尺度上的反馈作用,需要把动态植被模式耦合到气候模式里.本研究通过引进动态植被模式VEGAS(VEgetation-Global Atmosphere-Soil),在中国科学院大气物理研究所9层(IAP9L)气候模式的基础上,初步建立了一个新的IAP大气一植被耦合模式IAP9L_VEGAS.对该模式积分多年的结果分析表明:IAP9L_VEGAS可以较合理地模拟出植被生态系统生产力和植被、土壤碳库的总量及其季节变化,而且该模式模拟的叶面积指数的全球分布与观测资料十分接近.与未耦合动态植被模式的IAP9L模式模拟结果的比较表明:在非洲和南美等热带雨林地区,IAP9L_VEGAS模拟的叶面积指数比IAP9L中根据经验设置的大3.5以上,更接近观测;此外,IAP9L-VEGAS模拟的降水和近地面气温均较IAP9L更加接近观测实况.     

柠条适应极端干旱的生理生态机制 ——叶片脱落和枝条中叶绿体保持完整性

 为了探讨柠条适应极端干旱的生理生态机制,对盆栽柠条停止浇水造成土壤持续干旱直到叶片完全脱落,然后复水。干旱和复水期间,对土壤、叶片和枝条的相对含水量、叶片和枝条中的叶绿素含量以及超微结构进行了测定和观察。结果表明,干旱脱水过程中叶片中的色素含量下降,枝条中类胡萝卜素含量下降。复水4 d后,叶片中色素含量和枝条中类胡萝卜素含量上升并逐步达到正常水平。超微结构研究表明,柠条嫩枝的亚细胞组织中普遍含有叶绿体。正常条件下,无论是枝条还是叶片的亚细胞组织,叶绿体紧贴细胞壁。叶绿体中的类囊体排列整体有序。随着干旱的加剧,叶绿体脱离细胞壁,向细胞中央靠近。严重干旱造成了叶片叶肉细胞和叶绿体结构不可恢复性的破坏,包括外膜和膜片层结构,类囊体膜解体,淀粉粒消失,部分细胞器裂解成碎片。而嫩枝的亚细胞组织和叶绿体都保持完整。因此,柠条通过叶片脱落减少光照面积来适应极端干旱对自身造成的伤害,通过保持枝条中叶绿体的完整性和一部分叶绿素为复水条件下光合作用的快速恢复提供了保证。     

塔克拉玛干沙漠南缘3种荒漠植物光合特性的比较

在2008年6、7和8月中旬,以塔克拉玛干沙漠南缘固氮植物骆驼刺（Alhagi sparsiftia Shap．）和非固氮植物柽柳（Tamarx ramossimaLedeb．）、花花柴（Karelinia caspica Less．）为研究对象,研究了两种类型植物的净光合速率、光响应、CO：响应模型参数、叶绿素和叶氮...     

光照与紫外辐射对亚热带树木叶片排放CH4的影响

植物排放甲烷（CH4）的来源尚存很大争议,而光照和紫外辐射胁迫可能是植物排放CH4的重要影响因素．本研究选择亚热带常见树种米槠、木荷、浙江桂、罗浮栲、杉木、马尾松和柑橘7种树木为研究对象,利用控制实验研究了光照和增强紫外辐射对树木叶片CH4排放的影响．结果表明：7种树木叶片的平均CH4排放速率在光照条件下（21.176ng·CH4·g^-1DW·h^-1）是在黑暗条件下（9．699ng·CH4·g^-1DW·h^-1）的2．2倍,光照对不同树木叶片CH4排放速率的影响具有显著差异;在高UV-B辐射强度处理下,除浙江桂和柑橘外,其他5种树木的CH4排放速率均显著高于低UV—B辐射强度处理的CH4排放速率;树种及其与光照或UV辐射的交互作用对树木叶片CH4排放速率的都具有显著影响,光照或增强UV辐射强度对排放速率较低的树木种类排放CH4的促进作用更强．     

Adsorption of Cadmium from Aqueous Solution by Ficus religiosa Leaf Powder and Characterization of Loaded Biosorbent

The present investigation evaluates the adsorption effectiveness of Cd(II) ions on Ficus religiosa leaf powder (FRL). The experimental parameters chosen included time, pH, particle size, temperature, adsorbate, anion, and Pb(II) concentrations. The time data followed pseudo‐second‐order kinetics. Cd(II) adsorption increased from 1.38 to 75.17% with the increase in pH from 2 to 4 and further increase in pH to 5.5 resulted in its marginal increase to 77.52%. Based on regression coefficient values, the isothermic data fitted the various models in the order Langmuir > Redlich–Peterson > Temkin > Freundlich model. The maximum loading capacity of FRL was estimated to be 27.14 mg g^?1. The presence of Cl^?, , or Pb²⁺ exhibited adverse effect on Cd(II) uptake. The thermodynamic parameters of enthalpy (ΔH⁰) and entropy (ΔS⁰) were estimated to be 8.31 kJ mol^?1 and 38.22 J mol^?1 K^?1, respectively. SEM‐EPMA of the loaded FRL showed Cd(II) distribution at specific sites. The XRD patterns of Cd(II) loaded FRL sample showed disappearance of some peaks corresponding to β‐Ca(PO₃)₂; shifting of peaks and decrease in %RI corresponding to γ‐CaSO₄ phase. Positive shift of IR bands for the Cd(II) loaded sample was observed.     

Mangrove litter fall: Extrapolation from traps to a large tropical macrotidal harbour

Mangrove litter is a major source of organic matter for detrital food chains in many tropical coastal ecosystems, but scant attention has been paid to the substantial challenges in sampling and extrapolation of rates of litter fall. The challenges arise due to within-stand heterogeneity including incomplete canopy cover, and canopy that is below the high tide mark. We sampled litter monthly for three years at 35 sites across eight mapped communities in the macrotidal Darwin Harbour, northern Australia. Totals were adjusted for mean community canopy cover and the occurrence of canopy below the high tide mark. The mangroves of Darwin Harbour generate an estimated average of 5.0 t ha⁻¹ yr⁻¹ of litter. This amount would have been overestimated by 32% had we not corrected for limited canopy cover and underestimated by 11% had we not corrected for foliage that is below the high tide mark. Had we made neither correction, we would have overestimated litter fall by 17%. Among communities, rates varied 2.6-fold per unit area of canopy, and 3.9-fold among unit area of community. Seaward fringe mangroves were the most productive per unit of canopy area but the canopy was relatively open; Tidal creek forest was the most productive per unit area of community. Litter fall varied 1.1-fold among years and 2.0-fold among months though communities exhibited a range of seasonalities. Our study may be the most extensively stratified and sampled evaluation of mangrove litter fall in a tropical estuary. We believe our study is also the first such assessment to explicitly deal with canopy discontinuities and demonstrates that failure to do so can result in considerable overestimation of mangrove productivity.     

Photosynthetic response to different light intensities, water status and leaf age of two Berberis species (Berberidaceae) of Patagonian steppe, Argentina

Net photosynthetic rate (A) and stomatal conductance (gs) from leaves of Berberis buxifolia and Berberis heterophylla saplings were measured under different conditions of radiation and water availability and for leaves of different ages. Comparative studies of basic physiological performance would give insight how these shrubs survive and grow under this austral extreme ecosystem. B. buxifolia had higher A values than B. heterophylla for all light intensities measured. Values of gs for both Berberis species also declined as light intensity decreased. There was a negative relationship between A and water stress expressed as pre-dawn leaf water potential (ψ_lp) where the reduction in gs was the main factor that reduced A in both species. Also, A and gs of Berberis plants increased rapidly during the first days after leaf unfolding, reached a maximum value when the leaf was completely expanded, and then declined. These results could be used to estimate the responses of saplings to environmental conditions under the dynamic of natural stands in this austral extreme ecosystem and for restoration plans.     

Vegetation-groundwater dynamics at a former uranium mill site following invasion of a biocontrol agent: A time series analysis of Landsat normalized difference vegetation index data

Because groundwater recharge in dry regions is generally low, arid and semiarid environments have been considered well-suited for long-term isolation of hazardous materials (e.g., radioactive waste). In these dry regions, water lost (transpired) by plants and evaporated from the soil surface, collectively termed evapotranspiration (ET), is usually the primary discharge component in the water balance. Therefore, vegetation can potentially affect groundwater flow and contaminant transport at waste disposal sites. We studied vegetation health and ET dynamics at a Uranium Mill Tailings Radiation Control Act (UMTRCA) disposal site in Shiprock, New Mexico, where a floodplain alluvial aquifer was contaminated by mill effluent. Vegetation on the floodplain was predominantly deep-rooted, non-native tamarisk shrubs (Tamarix sp.). After the introduction of the tamarisk beetle (Diorhabda sp.) as a biocontrol agent, the health of the invasive tamarisk on the Shiprock floodplain declined. We used Landsat normalized difference vegetation index (NDVI) data to measure greenness and a remote sensing algorithm to estimate landscape-scale ET along the floodplain of the UMTRCA site in Shiprock prior to (2000–2009) and after (2010–2018) beetle establishment. Using groundwater level data collected from 2011 to 2014, we also assessed the role of ET in explaining seasonal variations in depth to water of the floodplain. Growing season scaled NDVI decreased 30% (p < .001), while ET decreased 26% from the pre- to post-beetle period and seasonal ET estimates were significantly correlated with groundwater levels from 2011 to 2014 (r² = .71; p = .009). Tamarisk greenness (a proxy for health) was significantly affected by Diorhabda but has partially recovered since 2012. Despite this, increased ET demand in the summer/fall period might reduce contaminant transport to the San Juan River during this period.     

福建铁观音茶园生态地球化学特征

东南沿海是铅等重金属的地球化学高背景区。该地区广泛分布酸性红壤,酸雨沉降、不适当施肥导致土壤酸化以及由此引发土壤重金属生态风险令人关注。以福建省铁观音主产区为研究区,采集了79个茶园的表层和亚表层土壤样、茶叶样品,测定了重金属元素以及土壤常量元素和理化指标。研究表明,福建铁观音茶园土壤中Hg、Pb、Se、Zn高含量主要由地质背景所引起,土壤常量组分、有机质、酸碱度等理化条件对土壤元素含量有一定的影响;铁观音茶树老叶中As、Cd、Cr、Hg、Se、Pb、F等非植物营养元素含量明显高于嫩叶,显示这些元素随植物生长逐渐累积的特征,而嫩叶中植物生长必需的营养元素Cu、(Ni)、Zn则高于老叶,反映出微量营养元素在茶叶生长部位相对富集的特征;多数情况下土壤与茶叶间元素含量相关性差,说明茶树对土壤元素的吸收累积受到多种复杂因素的影响。研究表明茶叶与土壤Pb、Cr具有显著正相关性,为建立铅污染土壤生态效应预测评价模型提供了基础依据。     

Effect of leaf distribution pattern on the interception storage capacity of leaf litter under simulated rainfall conditions

Rainwater interception by leaf litter is an important part of forest hydrological processes. The objective of this study was to investigate the interception storage capacity (ISC) of woodland leaf litter for three leaf distribution patterns, one flow path, two flow paths, and three flow paths, manually simulated via one-by-one leaf connection in the top leaf litter layer. A random pattern served as the control. Three different slopes (0°, 5° and 25°, representing flat, gentle and steep slopes, respectively) and two contrasting leaf litters (needle-leaf litter, represented by P. massoniana leaves, and broad-leaf litter, represented by C. camphora leaves) with a biomass of 0.5 kg/m² per unit area were applied, at a rainfall intensity of 50 mm/h. Results suggested that leaf distribution pattern greatly impacts litter drainage and hence affects leaf litter ISC. The delaying capacity of litter drainage initiation and ISC of broad-leaf litter were higher than those of needle-leaf litter under the same slope conditions. The maximum ISC (C_max) and minimum ISC (C_min) of leaf litter at flat and gentle slopes were higher than those at steep slope. C_min of the broad-leaf litter was two times higher than that of needle-leaf litter on average. When raindrops reached the litter layer, some were temporarily intercepted by the top litter layer while others infiltrated leaf litter sublayer along leaf edges, and in the process, some rainwater flowed through litter layer and contributed to lateral litter drainage along the potential flow path formed by leaves. The lateral litter drainage of broad-leaf litter was higher than that of needle-leaf litter, and the partitioning of rainwater into lateral litter drainage increased with increases in slope. The difference in leaf litter C_max among different slopes and leaf shapes decreased with flow path increasing. Therefore, leaf distribution pattern notably impact leaf litter ISC, which is similar to leaf shape and slope impacts. On inclined slopes, avoiding leaf accumulation to form flow path is helpful for improving ISC.