草丘微地貌对苔草泥炭沼泽枯落物分解的影响

苔草沼泽在北半球高纬度地区广泛分布,草丘微地貌是苔草泥炭沼泽普遍存在的外貌特征,草丘和丘间环境差异可能会引起枯落物分解的异质性。为此,选择长白山区敦化东明林场典型臌囊苔草(Carex schmidtii)沼泽为研究对象,采用分解袋法对臌囊苔草枯落物在草丘及丘间位置的分解差异及其影响因素进行研究。结果表明:草丘和丘间枯落物干重损失具有相似的变化趋势,但丘间枯落物总干重损失(40.20%±4.22%)和分解速率(0.0021±0.0001)d~(-1)均高于草丘枯落物总干重损失(21.70%±2.25%)和分解速率(0.0012±0.0001)d~(-1),且丘间枯落物分解速率具有较大的波动性;草丘和丘间粗孔分解袋枯落物干重损失分别比对应位置的细孔分解袋枯落物干重损失高(1.81%±0.32%)和(2.91%±0.30%),在草丘和丘间枯落物分解速率上,微生物贡献分别是土壤动物贡献的6.37倍和5.65倍,而丘间土壤动物和微生物对枯落物分解速率的贡献分别是草丘的1.79倍和1.59倍。相关分析显示,草丘丘间枯落物干重损失与相应位置积温呈显著正相关(P0.05),而枯落物干重损失与草丘水位呈显著负相关(P0.05),与丘间水位呈显著正相关(P0.05)。本研究表明,在草丘微地貌格局下,不同的水热组合影响土壤动物和土壤微生物分布及群落组成,从而对枯落物分解产生影响,而其丘间不稳定的水分环境则是影响苔草泥炭沼泽枯落物分解的关键环境因子。     

三江平原草甸湿地土壤呼吸和枯落物分解的CO2释放

利用静态箱-碱液吸收法研究了三江平原草甸湿地土壤呼吸和枯落物分解的CO2释放速率,讨论了影响CO2释放的环境因素,估算了枯落物分解的CO2释放对于总释放的贡献.结果表明,生长季,小叶章沼泽化草甸和小叶章湿草甸各部分CO2释放均具有明显的时间变化特征,温度和水分是重要制约因素.两类草甸湿地的平均土壤呼吸速率分别为4.33g·m-2·d-1和6.15g·m-2·d-1,枯落物分解的CO2平均释放速率分别为1.76g·m-2·d-1和3.10g·m-2·d-1,枯落物分解的CO2释放占总释放量的31%和35%,说明在碳素由地上植物碳库转移到地下土壤碳库的过程中,湿地枯落物是一个不可忽略的碳损失源.     

西双版纳热带山地雨林枯落物及其土壤水文功能

研究了云南西双版纳热带不同海拔梯度山地雨林枯落物层及土壤层水文功能.结果表明: 土壤容重随着海拔的增加而降低,土壤总孔隙度、非毛管孔隙度、毛管孔隙度、土壤最大持水率、最大持水量、有效持水量和土壤含水量随海拔的增加而增加,局部有所波动;雨季前期含水量、饱和含水量和有效调蓄水空间随海拔的增加而增加,其中,饱和含水量和土壤有效调蓄水空间在不同海拔区差异均显著(P<0.05).土壤渗透性能与总孔隙度和非毛管孔隙度均呈极显著正相关关系(P<0.01),其中,非毛管孔隙对土壤渗透性的影响更为显著.不同海拔枯落物未分解层厚度均占总厚度的一半以上,枯落物厚度均表现为未分解层＞半分解层;枯落物总蓄积量和半分解层蓄积量占枯落物总蓄积量的比例均随海拔的增加而增加,说明低海拔枯落物分解速度较慢,高海拔枯落物分解速度较快.不同海拔枯落物半分解层和未分解层最大持水量、最大持水率、自然含水率、有效拦蓄率和有效拦蓄量均随海拔的增加而增加,并且各海拔未分解层均高于半分解层,而有效拦蓄量深度随海拔的增加而降低,局部有所波动.综合未分解层和半分解层的变化规律可知,高海拔拦蓄能力较强,低海拔较弱.不同海拔枯落物持水量随着浸泡时间增加而增加;枯落物吸水速率随着浸泡时间增加而降低,12 h后枯落物吸水速率逐渐趋于饱和.不同海拔枯落物持水量与浸水时间可用对数方程表示;吸水速率与浸泡时间可用冥函数方程表示.综合分析各项因子,低海拔热带山地雨林水源涵养能力普遍低于高海拔.     

枯落物分解及其影响因素

本文从枯落物分解的阶段划分到分解过程中的质量损失、组分变化、性质转变等方面详细讨论了枯落物分解过程、特征及影响因素。枯落物分解主要包括物理淋溶、生物化学分解和破碎过程,其中物理淋溶和生物化学分解分别在分解前期和后期占据主导地位。枯落物分解过程具有阶段性和特征连续性,且普遍按照先快后慢的规律发生质量损失。难分解的物质逐渐累积,导致枯落物腐殖化程度增强,芳香性和吸附性增加,生物可降解性降低。枯落物分解过程营养元素变化多元化,C含量普遍下降,N和P则受各种因素影响或累积或释放。枯落物分解是多重因子综合作用的过程,其中枯落物性质是本质要素,而温度、水分、土壤生物群落等均对枯落物分解产生不同程度的影响。水分的增加可以加快淋溶从而促进枯落物分解,温度的增加在一定程度上可以增强微生物活性;土壤生物对枯落物分解有明显贡献,其中微生物在枯落物分解中占主导地位,土壤动物起到一定的辅助作用。在此基础上,提出枯落物分解机理、影响因子之间的交互作用、枯落物分解对生态变化的反馈等将是未来枯落物分解研究的重点。     

三江平原典型湿地枯落物早期分解过程及影响因素

枯落物分解是湿地物质循环和能量流动的关键环节,是维持湿地功能的重要过程之一。采用分解袋法对三江平原3种典型湿地植物枯落物分解过程及影响因素进行了研究。研究表明,在164d实验过程中乌拉苔草分解速率始终最快;在分解前103d中毛果苔草分解速率大于小叶章,但在103~164d间小叶章分解速率大于毛果苔草;分解164d,小叶章、乌拉苔草和毛果苔草枯落物的失重率分别为初始重的31.98%、32.99%和28.91%。分解过程中小叶章和毛果苔草枯落物中有机碳浓度波动较大,而乌拉苔草枯落物中持续下降;3种枯落物有机碳绝对含量都表现为净释放。小叶章枯落物中N浓度波动较大,绝对含量发生净释放;毛果苔草枯落物N浓度持续增加,绝对含量净增加;乌拉苔草枯落物N浓度先增加后减少,绝对含量发生净释放。3种枯落物中P浓度都先迅速下降后缓慢上升,绝对含量都表现为净释放。3种枯落物中C/N和C/P也相应的发生变化。小叶章和乌拉苔草枯落物分解速率与枯落物C/P显著相关,而毛果苔草枯落物与枯落物N浓度显著相关;对应3种枯落物分解速率的主要环境因子分别为土壤含水量、土壤容重和土壤温度。3种枯落物分解速率和营养物质含量动态受到枯落物自身质量和温湿条件、周围环境营养状况等自然环境条件的共同影响,相比而言,受枯落物质量的影响更大。     

上海市大莲湖池杉林三种优势植物枯落物分解动态

用枯落物分解网袋法,对上海市大莲湖湿地池杉林内3种优势植物池杉(Taxodium ascendens)、孔雀稗(Echinochloa cruspavonis)、日本看麦娘(Alopecurus japonicus)的枯落物进行了190 d的分解培养,测定了分解速率及其C、N、P养分元素释放动态.用收集器法对池杉林枯落物的数量进行了研究.结果表明,池杉林内池杉每年产生枯落物量为5.70t·hm-2,是该林地枯落物的主要来源.3种植物枯落物的分解速率(枯落物的干重量损失)依次为日本看麦娘＞孔雀稗＞池杉.C元素含量在3种植物枯落物中随时间显著下降;N、P元素在池杉枯落物中均有不同程度的富集,而在日本看麦娘和孔雀稗中则没有发生富集现象.     

枯落物覆盖对阔叶红松林土壤蒸发的影响

通过对枯落物覆盖下森林土壤蒸发的观测,研究了不同干重及类型的枯落物对土壤蒸发的影响,及其与含水率的关系。结果表明:土壤含水率相同,枯落物覆盖量越大,土壤蒸发量越小;不同类型的枯落物对土壤蒸发的抑制作用不同,在相同干重的枯落物覆盖下,未分解、半分解和分解的枯落物对土壤蒸发的抑制能力依次减弱。土壤蒸发量与枯落物质量呈对数关系。随土壤含水率的降低,土壤蒸发量减少,含水率在41%～38%时,每下降1%,75g、45g、15g枯落物覆盖下的土壤蒸发量依次减少2.38g、1.43g、1.30g,且在土壤含水率下降过程中,覆盖的枯落物分解程度越高,土壤蒸发速率降低越不显著。     

林地枯落物最佳蓄积量确定方法的探讨

本文根据最优化理论原理,在综合考虑森林枯落物抑制土壤蒸发、控制土壤侵蚀及影响土壤矿质层温度三个主要的生态因子的前提下,提出了确定林地枯落物最佳蓄积量的方法。研究工作中,依此确定出华北落叶松人工林和辽东栎林地的枯落物最佳蓄积量分别为16.0吨/公颐和10.5吨/公顷。通过改变模型中的参数,本方法可用于任何立地环境中去。     

三江平原沼泽湿地枯落物分解及其营养动态

分解袋法研究了三江平原典型沼泽湿地枯落物的分解速率和N、P营养动态.湿地枯落物的分解速率（0.000612～0.000945 d^-1）在群落间差异显著,分解480d,分别损失初始重的45.36%（Carexpseudocuraica）、35.32%（Carex lasiocarpa）、33.72%（Deyeuxia angustifolia）和29.13%（Deyeuxia angustifolia-Shrub）,即随淹水深度由大到小、淹水时间由长到短,枯落物分解由快到慢,说明湿地的淹水状况是影响枯落物分解速率的主要因素.分解过程中,漂筏苔草和毛果苔草枯落物N浓度持续上升,N在枯落物中积累;小叶章枯落物N浓度在第1个月快速下降而后缓慢上升,分解使枯落物释放N.各类枯落物P浓度的变化大致呈不同程度的降低趋势,分解使湿地枯落物均发生P释放.结果表明,微生物的营养需求状况决定了湿地枯落物N、P的动态变化,而其积累或释放的强度则可能与枯落物初始C：N和C：P的大小有关.     

三江平原小叶章湿地枯落物初期分解动态

通过4周淋洗分解试验，探讨了微生物活动和淋洗作用对三江平原沼泽湿地沼泽化草甸小叶章和湿草甸小叶章枯落物初期分解的影响.结果表明：两种小叶章植物初期分解的质量损失分别占当年分解物质损失量的59％和22％，28 d分解后枯落物残留量明显降低，并呈先快后慢的变化过程.两种枯落物中N、P含量均有明显下降，N含量分别下降了约3265%和2455%，P下降了36.71%和45.15％.抑制微生物处理的枯落物N、P含量较不抑制处理高，但差异不显著；抑制和不抑制微生物处理下枯落物释放到淋洗液N、P含量变化也不相同，但差异未达到显著水平.表明小叶章初期分解主要受淋洗作用的影响.两种小叶章植物的分解速率和养分损失速率差异均未达到显著水平.     

Wetland loss dynamics in southwestern Barataria basin,Louisiana (USA), 1945–1985

We determined spatial associations of wetland loss rates in a 950-km² study area in the southwestern Barataria basin of Louisiana's Mississippi River delta plain for four intervals spanning 40 years, 1945–1985. A geographic information system was used to analyze spatial and temporal changes.Annual wetland loss rates increased over the 40 years; the rate of increase in annual rates accelerated through 1980 and then began to decelerate. The average annual rate of wetland loss for the entire study area increased from 0.2%/yr during 1945–1956, to 1.2%/yr for 1956–1969, 1.9%/yr for 1969–1980, and 2.0%/yr for 1980–1985. Wetland loss was not uniform throughout the study area. Eight sub-areas were identified as having different densities and/or causes of loss. Processes implicated in the differing loss rates include sea level rise, shoreline erosion, accelerated subsidence along natural levees, canal modification of hydrologic flows, interference of dredged material with sheet flow, and saltwater intrusion. In some areas, several processes are believed to operate together to induce wetland degradation and wetland loss.     

The influence of weight loss on serum osteoprotegerin concentration in obese perimenopausal women

Objective: To assess the influence of weight reduction therapy on serum osteoprotegerin (OPG) concentration in obese patients and compare these results with normal‐weight controls. Research Methods and Procedures: Forty‐three obese women (BMI, 36.7 ± 4.1 kg/m²; mean age, 50.1 ± 4.5 years) were studied. The control group consisted of 19 normal‐weight women (BMI, 24.2 ± 2.1 kg/m²; mean age, 53.8 ± 5.2 years). In all patients, serum concentrations of OPG, C telopeptide of type I collagen containing the cross‐linking site (CTX), osteocalcin, parathormone, 25‐(OH)‐D₃ (vitamin D), and total calcium and phosphorus were assessed before and after a 3‐month weight reduction therapy. Results: In obese subjects, serum concentrations of OPG, 25‐(OH)‐D₃, osteocalcin, total calcium, and phosphorus were significantly lower, and serum concentration of parathormone was significantly higher, before weight reduction therapy in comparison with normal‐weight controls. After weight reduction, a significantly higher serum concentration of 25‐(OH)‐D₃ and CTX and significantly lower concentration of OPG were found. Discussion: Serum concentration of OPG was significantly lower in obese patients in comparison with normal‐weight controls. Weight reduction therapy resulted in further decrease in OPG serum concentrations. Therefore, OPG cannot be treated as a protective factor from bone loss in obese patients.     

Mitochondrial Syndromic Sensorineural Hearing Loss

Mitochondrial diseases (MD) are a clinically heterogeneous group of disorders that arise as a result of dysfunction of the mitochondrial respiratory chain. Sensorineural hearing loss (SNHL) is often associated to mitochondrial dysfunctions both in syndromic, nonsyndromic forms. SNHL has been described in association to different mitochondrial multisystemic syndromes, often characterized by an important neuromuscular involvement. Because of the clinical relevance of the associated neurological symptoms, the occurrence of SNHL is often underestimated and undiagnosed. In this study we evaluated the incidence of SNHL in a group of 17 patients with MD. We detected some degree of hearing impairment in 8/17 patients (47%), thus confirming the frequency of hearing impairment in MD. Furthermore, we want to highlight the role of the audiologist and otolaryngologist in the diagnosis and characterization of a MD, which should be suspected in all the cases in which the hearing loss is associated to signs and symptoms characteristic of mitochondrial dysfunction, especially if the family history is positive for hearing loss or MD in the maternal line.     

The sinking ark: pollution and the worldwide loss of biodiversity

Humans are making increasing demands on natural ecosystems. One recent study has concluded that our species is consuming or diverting some 40% of the net photosynthetic productivity of our planet. Many habitats are being converted to simpler systems which provide more harvestable goods to people. As a result, genetic diversity, species and whole ecosystems are disappearing; some scientists suggest that as many as 25% of the world's species could be lost in the next several decades.The sinking ark is usually characterized in terms of pollution, habitat loss, poaching, introduced species and illegal trade in wildlife products, but these are symptoms rather than causes. At a more fundamental level, many of the same factors which have enabled pollution to become such a problem have also been responsible for the loss in biodiversity; the most important factor is that the effects of pollutants on biodiversity have been considered an externality, an unintended side effect of industrial activity which brought measurable benefits to people. Development activities which have depleted biodiversity have proven profitable only because the real costs have been hidden.Keeping the ark afloat will require the Five-I Approach: investigation (learning how natural systems function); information (ensuring that the facts are available to inform decisions); incentives (using economic tools to help conserve biodiversity); integration (promoting a cross-sectoral approach to conserving biodiversity); and international support (building productive collaboration for conserving biodiversity).     

Disaster Risk Decision: A Dynamic Computable General Equilibrium Analysis of Regional Mitigation Investment

For implementation of specific actions to reduce risks, there is lack of a unified tool to compare different mitigation investment strategies and to prioritize alternative mitigation measures. Organizations usually address some operational risks such as business interruption (BI) losses. Computable general equilibrium (CGE) models are state-of-the-art economic tools to account for BI losses. This study proposed a new, improved dynamic CGE model to analyze and compare mitigation investment measures that aim at reducing BI losses. The new model, a time-recursive dynamic model reflecting the recovery and reconstruction period, connects reconstruction investment with reconstruction funds source, such as from government, household, enterprise, or outside a disaster-affected area. The 2008 Wenchuan earthquake in China was selected as a case study to illustrate the new model. Some interesting topics about mitigation investment were analyzed: (1) the relative importance of pre-disaster reduction investment versus post-disaster reconstruction investment; (2) post-disaster economic recovery with the contribution of insurance compensation; (3) the optimal ratio between mitigation funds collected from the disaster-affected area and that collected from outside the disaster-affected area; (4) the rational division of limited mitigation funds to each year during the restoration and reconstruction period.     

Thermal equilibrium of goats

The effects of air temperature and relative humidity on thermal equilibrium of goats in a tropical region was evaluated. Nine non-pregnant Anglo Nubian nanny goats were used in the study. An indirect calorimeter was designed and developed to measure oxygen consumption, carbon dioxide production, methane production and water vapour pressure of the air exhaled from goats. Physiological parameters: rectal temperature, skin temperature, hair-coat temperature, expired air temperature and respiratory rate and volume as well as environmental parameters: air temperature, relative humidity and mean radiant temperature were measured. The results show that respiratory and volume rates and latent heat loss did not change significantly for air temperature between 22 and 26 °C. In this temperature range, metabolic heat was lost mainly by convection and long-wave radiation. For temperature greater than 30 °C, the goats maintained thermal equilibrium mainly by evaporative heat loss. At the higher air temperature, the respiratory and ventilation rates as well as body temperatures were significantly elevated. It can be concluded that for Anglo Nubian goats, the upper limit of air temperature for comfort is around 26 °C when the goats are protected from direct solar radiation.     

A left/right comparison of sequential bone loss from the metacarpals of postmenopausal women

The rate of decrease of mean metacarpal cortical width was assessed by sequential radiographic morphometry for each hand separately in a series of 46 right-handed postmenopausal women observed for 222 patient-years. For the left hand, the mean rate was 0.0331 ± 0.0053 mm/year and for the right, 0.0310 ± 0.0060 mm/year. The difference between the hands in the rate of decrease was not significant. It is concluded that the higher work load of the dominant hand has no effect on the rate of bone loss from the metacarpals of postmenopausal women.     

苹果绵蚜为害产量损失测定

苹果绵蚜为害苹果的树干、枝,新稍及根部,从中吸取大量营养,使寄主生长发育不良,产量降低。经测定苹果绵蚜发生群落数与造成的产量呈负相关,而与产量损失率成正相关,在苹果单株产量108．19～154．20kg,苹果绵蚜群落数±30～＞150个的情况下,小国光和青香蕉品种的产量损失率分别为4．10％～38．81％和7．5％～32．04％。     

A novel P2RX2 mutation in an Italian family affected by autosomal dominant nonsyndromic hearing loss

Hereditary hearing loss (HHL) is a common disorder accounting for at least 60% of prelingual deafness. It is characterized by a large genetic heterogeneity, and despite the presence of a major gene, still there is a need to search for new causative mutations/genes. Very recently, a mutation within ATP-gated P2X(2) receptor (ligand-gated ion channel, purinergic receptor 2) gene (P2RX2) at DNFA41 locus has been reported leading to a bilateral and symmetrical sensorineural non-syndromic autosomal dominant HHL in two Chinese families. We performed a linkage analysis in a large Italian family with a dominant pattern of inheritance showing a significant 3.31 LOD score in a 2 Mb region overlapping with the DNFA41 locus. Molecular analyses of P2RX2 identified a novel missense mutation (p.Gly353Arg) affecting a residue highly conserved across species. Visual inspection of the protein structure as obtained from comparative modeling suggests that substitution of the small glycine residue with a charged bulky residue such as an arginine that is close to the ‘neck’ of the region responsible for ion channel gating should have a high energetic cost and should lead to a severely destabilization of the fold. The identification of a second most likely causative mutation in P2RX2 gene further supports the possible role of this gene in causing autosomal dominant HHL.