Cd对不同种类植物生长和养分积累的影响

溶液培养法研究了不同活度Cd2 对4种植物卷心菜、黑麦草、玉米和白三叶草生长和养分积累的影响．结果表明,随Cd2 活度增加,4种植物的生长速率和干物质产量均下降．白三叶草对Cd2 最敏感;黑麦草和玉米耐性较强;卷心菜在高ACd2 时敏感．Cd2 对Fe、Mn、Cu、Zn、Ca、Mg、P、S等养分积累的影响因植物种类而异．Cd2 降低Fe、Mn、Cu、Zn、Ca、Mg等的积累．P在4种植物中和S在除卷心菜外的3种植物中的积累比对照增加．卷心菜和白三叶草对Cd毒敏感性差异与Fe、Mn、Ca、Mg的积累受Cd2 影响程度不同密切相关．     

Temporal variation in microbial and plant biomass during summer in a Mediterranean high-mountain dry grassland

Aims

We assessed the temporal changes on microbial biomass in relation to changes in soil moisture, dissolved organic carbon and plant biomass during the summer season in a Mediterranean high-mountain grassland.

Methods

Temporal variations were tested by two-way ANOVA. The relationships among microbial biomass, plant biomass, soil water content, soil organic carbon, dissolved organic carbon and total soil nitrogen during the summer season were assessed by means of structural equation modeling.

Results

Microbial biomass did not show variation, while dissolved organic carbon and root biomass decreased throughout the summer. Aboveground plant biomass peaked in the middle of the summer, when soil water content was at its minimum. Soil water content directly and negatively affected soil microbial biomass, and positively affected dissolved organic carbon. Moreover soil microbial biomass and dissolved organic carbon were negatively related. Plant biomass effects on soil microbial biomass were driven by root biomass, which indirectly affected soil microbial biomass through effects on soil organic carbon and soil nitrogen.

Conclusions

The temporal dynamic of microbial biomass during the summer season appeared to differ from previous observations in temperate alpine communities, and indicated the drought resistance of the microbial community during the summer in Mediterranean high-mountain grasslands. During the dry period, microbial biomass may play an alternative role in soil carbon conservation.     

松嫩盐碱草地几种植物的土壤营养位分析

针对松嫩盐碱草地上的几种主要植物,以植物地上生物量和总和优势度（SDR）为土壤营养位效能指标,分别从多项土壤因子综合、可溶盐含量、总碱度、Na^ 含量、有机质含量、全氮含量角度进行了土壤营养位分析。讨论了松嫩盐碱草地植物种群分布格局与土壤营养的关系,指出松嫩盐碱草地植物种群分布格局的形成是可溶盐含量、总碱度、Na^ 含量、有机质含量、全氮含量5项主要土壤因子综合作用的结果,对于各植物种群土壤营养位的分化结果而言,没有一项土壤因子是起决定性作用的。     

Recovery of plant species composition and ecosystem function after cessation of grazing in a Mediterranean grassland

Short- and long-term changes in species composition, plant biomass production, and litter decomposition after cessation of grazing were examined in a Mediterranean grassland with high dominance of annual species and strong seasonality in biomass production. Short-term changes were assessed during three consecutive years in plots previously exposed to different grazing pressures and compared to plots in long-term (30–40 years) exclosures. Short-term cessation of grazing led in the short-term to an increase in relative biomass of annual crucifers and tall annual and perennial grasses, while biomass of annual legumes, annual thistles and short annual grasses decreased. Consequently, similarity increased between vegetation recently excluded from grazing and vegetation in long-term protected plots. Our research showed that in systems with high dominance of grasses and annual species, the rapid changes in plant species composition that occur after grazing cessation were associated with a fast recovery of the potential for biomass production to levels found in long-term protected plots, while litter decomposition rate did not change even after long-term cessation of grazing. Moreover, previous history of grazing did not affect plant litter decomposition, despite higher litter quality in grazed treatments. This study provides new insights about the processes involved in the diverse responses of ecosystem functions resulting from shifts in species composition associated with grazing cessation and land use change in Mediterranean grasslands.     

Spatial patterns and interspecific relations analysis help to better understand species distribution patterns in a Mediterranean high mountain grassland

The aim of this study is to investigate distribution patterns of species occurring at definite spatial scales and to address the main ecological factors that structure a Mediterranean high mountain grassland community. Following the protocols of the GLORIA long-term study, four summits were sampled during the year 2006 and 2007 in Sierra de Guadarrama (Spain). The data recorded on two of those summits were analysed for spatial pattern of species, interspecific associations and environmental relationships were determined from the recorded data. This was done by multivariate analyses (ordinations), SADIE analyses (distance indices) and Pearson χ² test, respectively. Results showed that chamaephyte species were more abundant in less disturbed situations whilst caespitose hemicryptophyte species and mosses were more abundant in disturbed ones. High mountain species were more abundant in less disturbed situations. Higher spatial heterogeneity was detected on northern and eastern slopes, which could be related to the increased environmental severity of northern exposures and to the greater intensity of the disturbances on eastern exposures. The frequent aggregated distribution of a few species may be related to facilitation processes due to their frequent participation in positive interactions. Finally we observed that positive pairwise associations of species were more frequent than negative associations. The relevance of the studied relationships lied in a better understanding of those threats on high mountain biodiversity induced by climate warming.     

云雾山天然草地植物生长规律

试验以云雾山优势种本氏针茅(Stipa bungeana)、大针茅(Stipa grandis)与伴生种百里香(Thymus mongolicus)、铁杆蒿(Artemisia sacrorum)、厚穗冰草(Agropyron dasystachys)、二裂萎陵菜(Potentilla bifurca)和阿尔泰狗娃花(Heteropappus altaicus)为研究对象,对每一植物选择典型植株进行标记,重点从植物株高和地上单株生物量两个方面对其生长动态,进行一个生长周期(返青期-枯黄期)的观察测量,结果表明:(1)植物生长在株高和地上单株生物量达到最大值之前,均基本符合Logistic生长模型;(2)在植物整个生长过程中,地上单株生物量月变化与株高存在动态分形关系:lnB=D×lnH lnC.(3)植物生长除受其生物学特性支配外还受外界环境因子的限制,在干旱半干旱地区,降雨量显得尤为重要,在本次试验中,植物株高增长和地上单株生物量月变化均与降雨量累积存在着极显著的对数相关性:y=a×lnx b.     

Burrowing activities of kangaroo rats and patterns in plant species dominance at a shortgrass steppe-desert grassland ecotone

Abstract. Our objective was to evaluate the effects of burrowing activities by banner-tail kangaroo rats (Dipodomys spectabilis Merriam) on plant community structure and species dominance for two patch types at the ecotone between shortgrass steppe and desert grassland in New Mexico, USA. 10 mounds produced by kangaroo rats were selected in patches dominated by Bouteloua gracilis (the dominant in shortgrass steppe communities) and 10 mounds were selected in patches dominated by B. eriopoda (the dominant in Chihuahuan desert grasslands). Plant cover and density by species were sampled from three locations associated with each mound: the mound proper, the edge of the mound in the transition area, and the off-mound vegetation. Similar cover of B. eriopoda for the edges of mounds in both patch types indicates the ability of this species to respond to animal disturbances regardless of the amount of cover in the surrounding undisturbed vegetation. By contrast, cover of B. gracilis was low for all mounds and mound edges in patches dominated by this species. Much higher cover of B. eriopoda on mound edges compared to the undisturbed vegetation in B. gracilis-dominated patches indicates that kangaroo rats have important positive effects on this species. Lower cover of perennial grasses and higher cover of forbs, shrubs, and succulents on the edges of mounds in B. eriopoda-dominated patches compared to patches dominated by B. gracilis indicate the importance of surrounding vegetation to plant responses on disturbed areas. Our results show that kangaroo rats have important effects on both species dominance and composition for different patch types, and may provide a mechanism for small-scale dominance patterns at an ecotone; thus providing further support for their role as keystone species in desert grasslands.     

Effect of fire-derived chemicals on germination and seedling growth in Mediterranean plant species

The promoting effect of smoke-derived chemicals (e.g. karrikinolide and cyanohydrin) on germination in many plants from Mediterranean-type ecosystems such as South Africa and south-western Australia is well documented. However, very little is known about (1) the relative importance of different compounds and their possible interactive effects, (2) their role in enhancing seedling growth in wild plants, and (3) their effect on the germination of plants in the Mediterranean Basin. To fill these gaps in knowledge, we performed experiments to evaluate the effect of smoke water, karrikinolide, mandelonitrile (a cyanohydrin analogue), potassium nitrate and gibberellic acid on the germination and seedling growth of 37 species from the Mediterranean Basin. The results suggest that germination and/or seedling growth of 21 species are enhanced by at least one of the fire-derived chemicals. There were positive correlations between most of the compounds tested in terms of germination response, but synergetic and inhibitory effects were also detected. Stimulation of germination was most prominent in species with annual life cycles. Fire-derived chemicals were more effective in stimulating root growth than shoot growth. In conclusion, we provide novel evidence that the recruitment of different Mediterranean species may be enhanced by different smoke compounds, and that synergetic and inhibitory effects of chemical compounds are important in the germination ecology of plants.     

Ideal nutrient productivities and nutrient proportions in plant growth

Abstract I propose that one single formulation can be applied to relate growth and content of several nutrients, including the most important macronutrients, of most plant species. The plant growth rate is proportional to the nutrient content minus a given minimal concentration of the nutrient in minimum. The proportionality factor, the nutrient productivity, and the minimum concentration are species specific properties. The nutrient productivity formulation is shown to apply for very different plant species and for different nutrients.     

中国北方草地植物群落季节生长格局模拟

中国北方草地横跨干旱、半干旱及亚湿润干旱气候区,水分是限制中国北方草地植物群落生产力的主要气候因子.采用基于水分平衡过程的、简单的植物群落模型,利用460个气象站40年气象数据的月平均值,模拟中国北方7种草地类型的季节及年生长、叶片投影盖度(FPC)、蒸发系数(k)及净第一性生产力(NPP).野外观测数据对模型的验证显示模拟结果与观测值相符较好.温性草地自东向西,青藏高原自东南向西北,植物群落的k、NPP与FPC呈递减趋势,显示了中国温性草地自东向西,青藏高原自东南向西北逐渐干旱的水分梯度;其中高寒草甸的3个模拟参数值均最高,高寒草原FPC次于高寒草甸,而NPP却与温性典型草原相近,温性典型荒漠的3个参数最低.高寒草甸、高寒草原、温性草甸草原、温性典型草原、温性荒漠草原、温性草原化荒漠和温性典型荒漠等7种类型草地的畜群承载力约为每公顷5.2、2.3、3.6、2.1、1.0、0.6和0.2只羊单位,区域最适恢复植被盖度分别以93%、79% 、56%、50%、44%、38%和37%为宜.     

云南省南部山地7种主要入侵植物沿公路两侧的扩散格局

公路被认为是促进入侵植物扩散的主要通道之一。为了揭示公路与植物入侵的关系, 我们在云南省北热带和南亚热带地区选择13条公路, 按照公路性质、修建年代以及干扰历史将公路分为高、中、低3个干扰水平, 研究了7种主要入侵植物在公路两侧的扩散格局, 以及环境因素(干扰、光照、坡向、气候带)对扩散格局的影响。结果表明: 紫茎泽兰(Eupatorium adenophorum)、飞机草(E. odoratum)、胜红蓟(Ageratum conyzoides)和肿柄菊(Tithonia diversi-folia)的密度以及紫茎泽兰的频度沿公路扩散格局呈明显的单峰变化, 峰值一般都出现在4 m以内。高干扰公路两侧, 紫茎泽兰、飞机草、胜红蓟、肿柄菊与金腰箭(Synedrella nodiflora)的密度以及紫茎泽兰、飞机草、胜红蓟、肿柄菊的频度均明显高于中、低干扰公路, 说明高干扰公路比中、低干扰公路更有利于促进植物入侵。高光水平下紫茎泽兰、飞机草、胜红蓟的密度以及紫茎泽兰、胜红蓟和金腰箭的频度明显大于中、低光水平, 说明高光水平显著促进公路两侧的这4种入侵植物向远距离扩散。紫茎泽兰、胜红蓟与金腰箭的密度在阳坡显著高于阴坡。紫茎泽兰与肿柄菊主要出现在南亚热带, 而飞机草与金腰箭主要出现在北热带, 胜红蓟与赛葵(Malvastrum coromandelianum)在两种气候带中均有出现。羽芒菊(Tridax procumbens)在公路两侧出现的频率与密度均很低, 无统计学意义。因此, 公路两侧的生境应作为防治外来植物入侵的重点, 提高公路两侧本地植被郁闭度将有利于控制紫茎泽兰等外来植物的进一步扩散。     

Non-neutral patterns of species abundance in grassland communities

Although the distribution of plant species abundance in a Minnesota grassland was consistent with neutral theory, niche but not neutral mechanisms were supported by the ability of species traits to predict species abundances in three experimental grassland communities. In particular, data from 27 species grown in monoculture showed that species differed in a trait, R *, which is the level to which each species reduced the concentration of soil nitrate, the limiting soil nutrient and which is predicted to be inversely associated with competitive ability for nitrogen (N). In these N-limited habitats, species abundance ranks correlated with their predicted competitive ranks: low R * species, on average dominated. These correlations were significantly different than expected for neutral theory, which assumes the exchangeability of species traits. Additionally, we found that changes in relative abundance after environmental change (N-addition or disturbance) were not neutral but also were significantly associated with R *.     

Biochars produced from individual grassland species differ in their effect on plant growth

Biochar, pyrolyzed biomass, has been shown to be a promising way to improve plant productivity and soil quality. Biochar characteristics and its effect on plant performance depend strongly on the type of feedstock from which it is made. However, whether biochars produced from individual grassland species differ in their characteristics and effects on plant growth when applied to soil is poorly understood. The aim of this study was to examine how soil application of pyrolyzed and non-pyrolyzed biomass originating from different grassland species influences plant performance.We measured the growth of the forb Jacobaea vulgaris in soil amended with pyrolyzed or non-pyrolyzed biomass of seven different plant species, and in control soil without amendments.The characteristics (nutrient content, C:N) and effects on plant growth of both pyrolyzed and non-pyrolyzed biomass differed significantly between species from which the biomass originated (‘feedstock species’). For most feedstock species there was no relationship between the effects that the pyrolyzed and the non-pyrolyzed biomass had on plant performance. Our results show that pyrolyzed grassland species differ in their characteristics and their effect on plant growth when amended to soil. This shows that it is important to test what the effect of pyrolysing a chosen feedstock is on a species before applying it on a larger scale and that potentially biochar with predefined effects could be designed for specific purposes.     

Decomposition and nutrient dynamics in mixed litter of Mediterranean species

In the last decade a great research effort addressed the effects of litter diversity on ecosystem functions, reporting both synergistic and antagonistic effects for decomposition dynamics. Four coexisting Mediterranean species, representing a range of litter quality, were used to arrange litter mixtures at three diversity levels for a litterbag decomposition experiment. Species identity appeared as the major determinant for litter mass loss (Coronilla emerus～Hedera helix>Festuca drymeia>Quercus ilex) and nutrient release, with rates for all leaf litter types following the sequence K>N>Mg≥Ca>>Fe. Additive diversity effects were prevalent pooling together all data but also for nutrients separately. Antagonistic interactions were more common than synergistic in the cases of mass loss, N and Ca contents, but not for K, Mg and Fe dynamics. The number of species in the litterbag significantly affected the outcome of non-additive interactions, which were mostly antagonistic for two-species mixtures, and synergistic for the combined 4 species. Litter quality appears to be the most important factor affecting mass loss and nutrient dynamics, while litter diversity, influencing the rates of these processes, plays an important role in reducing their variability, thus suggesting a greater stability of ecosystems properties in presence of mixed litter.     

Associations between plant growth forms and surface rockiness explain plant diversity patterns across an Afro-montane grassland landscape

A complex set of variables may explain biodiversity patterns both locally and regionally. Evidence exists that greater plant species richness can be associated with localised areas containing a greater percentage of rock exposure. Here, we test whether this is the case at the landscape scale, using semi-natural Afro-montane grassland in southern Africa. Plants were inventoried, percentage rock exposure calculated, and each site graded according to three levels of rockiness. Soil samples from each site were then analysed for particle size, as well as for levels of carbon, nitrogen and available phosphorus. Species richness and the compositional similarity of assemblages were compared between the three rockiness categories. Plants were then categorised into their respective growth forms, and species richness within each group compared across the rockiness categories. Greater species richness in rockier landscapes was driven by two particular plant growth forms, geophytes and perennial grasses. However, no overall plant assemblage compositional changes were recorded between the various rockiness categories, indicating that very few species are not associated with rocky areas in some way in this landscape. This shows that plant species within certain functional groups are naturally more responsive to certain abiotic ecosystem elements than others across a landscape. In turn, this highlights the significance of high habitat heterogeneity in structuring plant communities. Consequently, when an abiotic feature such as rockiness is observed across a landscape, it provides a surrogate for the spatial heterogeneity of certain plant communities.     

A nutrient medium for diverse applications and tissue growth of plant species in vitro

The basal salt formulation of a medium is a vital but often overlooked component in many in vitro applications, as it regulates the growth and morphology of plant tissues by providing essential nutrients. The MS and B5 formulations are the two most widely used basal media, yet they are suboptimal for many species. The objective of this study was to evaluate the BDS (modified B5) basal salt formulation for in vitro growth and development using rice, maize, soybean, cotton, onion, tobacco, muscadine, raspberry, and gerbera daisy as test species. The responses measured for each species included callus growth (biomass production), plant regeneration, micropropagation rate, hairy root growth, and production of secondary metabolites. BDS was compared to MS, B5, and BABI, a high-calcium version of BDS (440?mg/l?CaCl₂). For the majority of the species and responses measured, the results obtained with BDS and/or BABI were equal to or better than those obtained with MS or B5. Because of the wide range of plant species and in vitro systems included in this study, we conclude that BDS??or simple variations of BDS, such as BABI??are better balanced for a variety of uses in plant biotechnology, research, and production systems than either MS or B5.     

Influence of nutrient management on growth and nutrient use efficiency of two plant species for mineland revegetation

Rehabilitation of degraded areas by mining activities is necessary to achieve sustainable mining. For an effective revegetation, the understanding of plant growth and the nutrient requirements of native plant species, especially those with the potential to be used in the rehabilitation of mined areas such as waste piles or mine pits, is indispensable. In this study, we evaluated the growth performance, nutrient levels, and nutrient use efficiency of an endemic plant (Mimosa acutistipula var. ferrea) and ruderal shrub (Solanum crinitum) that are both found in ferriferous savannas, locally called “canga” in Carajás Mineral Province, Brazil. An experiment was conducted under greenhouse conditions using samples of three different soils (oxisol, canga soil, and iron mining waste) without and with nutrient application; additionally, an omission trial was carried out in canga soils. Fertilization increased the growth of both plant species in all substrates. Macronutrient omission reduced the growth of plants stronger than micronutrient omission, indicating that the lack of N, P, and K may especially impact the rehabilitation of areas. The growth of S. crinitum was higher than M. acutistipula var. ferrea, highlighting its preponderance in mineland rehabilitation, although concerns regarding its role as a ruderal species persist. Therefore, further research is necessary for a risk assessment of the propagation of S. crinitum within mineland restoration projects.     

The impact of human pressure on landscape patterns and plant species richness in Mediterranean coastal dunes

We analyze the spatial patterns of natural dune cover patches and their plant richness, comparing coastal sites with different levels of human pressure in central Italy. We created a detailed land cover map of dune sites. The spatial pattern of natural dune cover types was characterized by computing a set of patch-based metrics. To quantify patch plant richness, we used 16 m² vegetation plots, randomly distributed on coastal dune cover types. For each patch, the richness of the entire pool of species and of three guilds (i.e., typical dune, ruderal, and alien species) was considered. We compared different levels of human pressure on coastal dunes focusing on pattern metrics and floristic information by using the nonparametric Kruskal–Wallis test. In sites with high human pressure, we have observed a general simplification in the natural dune spatial pattern and a decline of plant richness but with a specific response for each cover type. Alien and ruderal species presented low richness in all patches. In coastal dunes, the harsh ecological conditions and the strong sea–inland gradient shape the distribution of human activities and control the number of ruderal species. The approach effectively describes fragmentation and biodiversity in dune ecosystems.