Direct, positive feedbacks produce instability in models of interrelationships among soil structure, plants and arbuscular mycorrhizal fungi

Current conceptual models of reciprocal interactions linking soil structure, plants and arbuscular mycorrhizal fungi emphasise positive feedbacks among the components of the system. However, dynamical systems with high dimensionality and several positive feedbacks (i.e. mutualism) are prone to instability. Further, organisms such as arbuscular mycorrhizal fungi (AMF) are obligate biotrophs of plants and are considered major biological agents in soil aggregate stabilization. With these considerations in mind, we developed dynamical models of soil ecosystems that reflect the main features of current conceptual models and empirical data, especially positive feedbacks and linear interactions among plants, AMF and the component of soil structure dependent on aggregates. We found that systems become increasingly unstable the more positive effects with Type I functional response (i.e., the growth rate of a mutualist is modified by the density of its partner through linear proportionality) are added to the model, to the point that increasing the realism of models by adding linear effects produces the most unstable systems. The present theoretical analysis thus offers a framework for modelling and suggests new directions for experimental studies on the interrelationship between soil structure, plants and AMF. Non-linearity in functional responses, spatial and temporal heterogeneity, and indirect effects can be invoked on a theoretical basis and experimentally tested in laboratory and field experiments in order to account for and buffer the local instability of the simplest of current scenarios. This first model presented here may generate interest in more explicitly representing the role of biota in soil physical structure, a phenomenon that is typically viewed in a more process- and management-focused context.     

导入Prd29A:DREB1 A融合基因获得抗逆性小麦的探索与实践

介绍了来自拟南芥的DREB转录因子在植物抗逆性中的作用 ,提出了通过导入Prd2 9A :DREB1A融合基因获得抗逆性小麦的策略     

广州市6个公园地被植物应用现状调查——对耐旱型地被的选择与思考

文章调查了广州市6个城市公园的地被植物,归纳总结其应用种类和配植情况,分析植物在大气干旱的情况下所表现出的形态变化。结合文献查阅,总结出部分耐旱型园林地被植物,并探讨了如何更好地通过植物配置的方式达到园林节水的目的。     

管涔山地木耳生物量及伴生植物的初步研究

对山西省管涔山地木耳（Nostoc commune Vaucher）的生物量及其分布进行了初步研究。该地区地木耳的平均生物量为11.1 kg/hm2,平均含水量为69.4%.地木耳群落植物种类共有7科,11属,13种,同地木耳生长关系比较密切的植物为黄花蒿（Artemisia annua L.）和阿尔泰狗娃花[Heteropappus altaicus （willd.） Novop.]。     

Characteristics of Nutrient Contents and Evaluation of Nutritional Value of the Alpine Grassland Plants in the Source Area of the Yellow River北大核心CSCD

In order to explore the characteristics of nutrient contents and scientifically evaluate the nutritional value of the alpine grassland plants in the source area of the Yellow River, the plants of the five different alpine grasslands were selected as the research objects, and the content of crude protein (CP), ether extract (EE), crude fiber (CF), crude ash (CA), total phosphorus (TP) of the plants were determined. At the same time, the principal component analysis method was used for quantitative comprehensive evaluation of the plants nutritional value. The results showed that the CP content of the plants in all alpine grasslands was between 12.78%~15.35%, the EE content was between 2.63%~3.38%, the CF content was between 17.56%~25.16%, the CA content was between 5.52%~11.53% and the TP content was between 0.11%~0.27%. The order of nutrient value of plants in different alpine grassland from high to low was: degraded alpine meadow > native alpine meadow > swamp meadow > degraded alpine steppe> native alpine steppe;The order of yield per unit area of the total nutrients of plants in different alpine grasslands from high to low was: swamp meadow > native alpine meadow > native alpine steppe> degraded alpine steppe> degraded alpine meadow;The order of nutrient value of different plant species from high to low was: Leguminosae>Forbs >Cyperaceae>Gramineae. © 2019 Authors. All rights reserved.     

莲花铅厂周围植被消亡动态与抗铅植物研究

莲花铅厂在2002-2004年生产期间污染严重,导致大量的植物死亡。对此进行了调查、测定和分析,结果表明:铅污染源呈梯度性空间变化,植被的消亡与此有一定的相关性;5种植物表现出较强的抗铅性。     

STUDY ON ULTRASTRUCTURE IN SEVERAL TYPICAL HALOPHYTES

<正> The characteristics of form and the structure of typical salt plants are usually consid-ered as suitable to the condition of salinity. So after studying their microstructure, we alsodid more careful observation of their ultrastructure and found some characteristics. Thesecharacteristics can not only explain the way in which they have adapted to salinization but     

稀土元素对植物生物学作用机制的研究进展

稀土元素在农业上得到了广泛的应用,产生了显著的经济效益。人们对稀土元素生物学效应 的作用机制进行了很多研究,提出了许多论点。从稀土元素在植物体内的赋存、稀土元素对植物光合 作用的影响机制、稀土元素对细胞中Ca的竞争取代机制、稀土元素对生物体内自由基的清除机制和 稀土与生物大分子的紧密结合及在细胞水平的定位五个方面综合分析了稀土元素对于植物体作用 机制的最新研究成果,为稀土农用技术的研究提供新的思路。     

伏牛山自然保护区珍稀濒危植物资源现状与保护对策

本文论述了伏牛山自然保护区珍稀濒危植物资源现状、区系特征,分析了珍稀濒危植物产生的原因,提出了保护珍稀濒危植物资源相应对策。     

运用植物打造低碳生活

随着全球工业经济的发展、人口的剧增、人类欲望的无限上升和生产生活方式的无节制,全球气候面临越来越严重的问题,二氧化碳排放量越来越大,地球臭氧层正遭受前所未有的危机,全球灾难性气候变化屡屡出现,已经严重危害到人类的生存环境和健康安全。为此,人们提出＂低碳生活＂（low-carbonlife）新概念,是指生活作息时所耗用的能量要尽力减少,从而减低碳,特别是二氧化碳的排放量,以减少对大气的污染,减缓生态恶化。本文通过对绿色植物能够吸收大量二氧化碳及有毒气体等进行分析,指出绿色植物在营造低碳生活中将会发挥巨大的作用。