【作者】 李天才；

【导师】 张德罡；

【作者基本信息】 甘肃农业大学 ， 草业科学， 2013， 博士

【摘要】 为了了解青海湖北岸草地矿物元素特征及其分布格局，探讨草地矿物元素蓄积分异行为发生的可能机制，明确在过度放牧和围栏封育等人类活动干扰下草地矿物元素蓄积分异行为是其对外界环境变化的一种“应激”响应，揭示草地矿物元素对于草地生态系统演替的敏感性。依据草地类型和海拔高度，分别选择河边滩地(垂穗披碱草型高寒草甸)、那仁车站(芨芨草型温性干草原)、烂泥湾(紫花针茅型高寒山地干草原)和加洋沟山顶(小嵩草草甸)等地的退化草地和封育草地为试验样地，通过草地植被群落调查，植物和土壤样品采集、分析，取得以下主要结论：1）青海湖北岸草地植物中矿物元素的“四个特征，两个格局”矿物元素特征谱特征、垂直带状谱特征、与株高和地上生物量之间负相关特征以及草地植物的指示性特征是草地矿物元素的“四个特征”。具有与地形地貌相一致的空间分布格局，如河边滩地、那仁车站、烂泥湾和加洋沟，海拔由3209m、3216m、3291m、3462m，退化草地植被中B含量逐渐升高，分别为14.24mg/kg、15.48mg/kg、16.25mg/kg、19.84mg/kg（P＜0.05）；封育草地中矿物元素随封育时间的增加而降低的时间分布格局，如那仁车站封育期5年和20年草地植被中Zn分别为77.01mg/kg、55.46mg/kg（P＜0.05）。2）草地植物中矿物元素的蓄积分异行为及其内外动力学机制退化草地植物中矿物元素具有蓄积分异性，如烂泥湾退化、封育草地植被中Cu分别为10.48mg/kg、7.275mg/kg（P＜0.05），退化草地植被中Cu蓄积增加了44.1%。封育草地植物中重金属具有蓄积分异性，如河边滩地退化、封育草地植被中Pb分别为3.915mg/kg、5.125mg/kg（P＜0.05），封育草地植被中Pb蓄积增加了30.9%。为了解释矿物元素蓄积分异行为发生的动力学机制，对生物体内矿物元素营养供给与平衡关系进行了一种假设，当某一矿物元素在其耐性范围内供给相对不足时，生命体处于一种对该矿物元素“饥饿”的状态，为了适应这种矿物元素的“饥饿”状态，生命体及时通过调节矿物元素需求量并适量储备矿物元素于体内，以满足生命活动对于矿物元素的及时所需。即生命体为了适应矿物元素的“饥饿”状态，体内蓄积矿物元素的现象，形象地称为矿物元素的“饥饿效应”。矿物元素“饥饿效应”假说，阐释了退化草地中矿物元素蓄积分异行为发生的内动力这一科学问题；诠释了草地植物中矿物元素与株高之间负相关性、与地形地貌相一致的空间分布格局等现象。矿物元素的“饥饿效应”是草地植物中矿物元素蓄积分异行为发生的内动力之一；而全球气候变化和人类活动干扰则是草地矿物元素蓄积分异行为发生的主要外动力。3）草地生态系统演替进程中矿物元素响应的数学模型退化演替进程中矿物元素蓄积分异行为响应的数学模型：C退(t)=Cb(1-exp(-α t))。封育演替进程中矿物元素蓄积分异行为响应的数学模型：C封(t)=Cbexp(-β t)。4）作物种植试验和高原富铁营养抗缺氧作用大坂山、拉脊山地区作物种植试验和西宁盆栽试验，较好地阐释并肯定了青海湖北岸草地植物中矿物元素具有与地形地貌相一致的空间分布格局，以及垂直带状谱特征等结论。同时，对于草地矿物元素的“饥饿效应”假说理论的检验与完善提供了部分试验依据。青海湖北岸草地植物以及大坂山、拉脊山地区种植青稞和胡萝卜中矿物元素铁的空间分布格局，提示：高原植物中铁元素具有抗高原缺氧作用。如大坂山2009年海拔2817m、2920m、3562m、3574m处种植青稞中Fe含量分别为93.60mg/kg、609.9mg/kg、799.1mg/kg、1360mg/kg（P＜0.05）。高海拔缺氧环境下植物因呼吸作用的增强，驱使其铁营养的“饥饿”状态而蓄积分异，即高原植物中富铁营养具有抗高原缺氧的作用。5）青海湖北岸人工草地中矿物元素特征青海湖北岸人工草地植物与天然草地一样，其中矿物元素具有特征谱的特征和随着海拔高度的增加而增加的空间分布格局。如铁路边坡、三角城羊场、县城西的海拔分别为3216m、3220m、3287m，各样地垂穗披碱草中Zn分别为30.07mg/kg、37.96mg/kg、42.01mg/kg（P＜0.05）。青海湖北岸人工草地相对于天然草地植物中矿物元素含量为低。按照矿物元素“饥饿效应”假说理论，天然草地植物中矿物元素的“饥饿效应”驱动了其中矿物元素的蓄积分异。6）矿物元素循环及其在草地畜牧业生产实践中指导作用草地土壤中矿物元素在生物地球化学循环作用下，形成了青海湖北岸草地植物中矿物元素的垂直带状谱特征，以及与地形地貌相一致的空间分布格局。经过草地植物—草地畜牧业生产等一系列食物链传递，又将部分矿物元素传递给我们人类，即矿物元素通过生物地球化学循环，不仅稳定地维持着草地生态系统的平衡与健康，而且对于草地畜牧业可持续发展和畜牧业产品的品质有着重要影响。利用草地矿物元素的各种特征和时空分布格局，可进行草地类型的划分，建立草地演替进程中矿物元素响应的数学模型等。在草业生产实践中，对于草地植物生长与矿物元素营养的补充供给的监测、管理具有指导作用，实现优质、高产的草业资源以满足草地畜牧业生产与可持续发展的需求。按照草地矿物元素“饥饿效应”假说，在草业生产中应注意草地植物中矿物元素营养的“饥饿效应”现象，避免矿物元素营养因“饥饿”状态的蓄积分异行为而造成的假象，以正确、有效、科学地补给草地植物必需的矿物元素营养。更多还原

【Abstract】 The aims of this study were to get to know the characteristics of mineral elements accumulationdifferentiation and to investigate their distribution pattern in grassland plants on the north bank of Qinghai Lakeand to find out the possible mechanism for their accumulating differentiation and the distribution patternscaused by the succession of grassland ecosystem. It can be defined as a “stress” response to the changes ofenvironmental conditions especially the influence of human activities, such as overgrazing and grasslandenclosure. Four investigation sites were selected based on grassland types and altitude: Hebiantandi (Elymusnutans, alpine meadow), Naren Railway Station (Achnatherum splendens, temperate steppe), Lanniwan (Stipapurpurea, alpine mountaine meadow) and the top of Beishanjiayanggou (Kobresia pygmaea, alpine meadow).The main results are as follows:1）The mineral elements in plants showed four characteristics and two distribution patternsThe mineral elements in grassland plants showed a characteristic spectrum, a vertical-banded spectrum, anegative correlation with plant height and aboveground biomass.The spatial distribution of mineral elements in grassland plants showed a pattern of increasing with alongwith the altitude. In which, the contents of B in degraded grassland in Hebiantandi, Naren Railway Station,Lanniwan and Beishanjiayanggou were14.24mg/kg,15.48mg/kg,16.25mg/kg and19.84mg/kg and the relatedaltitude were3209m,3216m,3291m and3462m respectively；The time distribution pattern of mineralelements in grassland plants was that the content of mineral element decreased with the time of enclosure. Inwhich, the Zn contents of grassland plants in the area of Naren Railway Station were77.01mg/kg and55.46mg/kg after enclosure for5and20years respectively（P＜0.05）.2）Accumulating differentiation behavior of mineral elements in grassland and its kinetic mechanismsThe mineral elements in plants of degraded grassland showed a characteristic of accumulatingdifferentiation. The content of Cu in degraded grassland in Lanniwan, increased from7.275mg/kg to10.48mg/kg (44.1%, P＜0.05) compared with that in enclosed grassland; The content of Pb in enclosed grassland inLanniwan, increased from3.915mg/kg to5.125mg/kg (30.9%, P＜0.05) compared with that in degradedgrassland. In order to find out the possible mechanism for their accumulating differentiation behavior of mineralelements, we proposed a hypothesis to explain the supply-demand balance of mineral element nutrition in thebody of organisms. When the mineral elements supply is relatively insufficient but still in the tolerant range oforganisms, they would fall into a “hungry” state for this element, in order to grow well the organisms wouldadjust their demand for mineral elements timely and begin to store them accumulating in their body. We call thisphenomenon “Starvation Effect”.“Starvation Effect” hypothesis theory has answered the question why mineral elements accumulatedifferently in plants and it can scientifically explain why the correlation between mineral elements content andplant height is negative. It also can be applied to some phenomena such as the spatial distribution patterns of mineral elements in plants.“Starvation Effect” might be the endogenetic force for the mineral elements to accumulate in plants and theclimate change and human activity’s interference as the main exogenetic force.3）Mathematical models of mineral elements in accumulating differentiation in the process of grasslandecosystem succession were established.The mathematical model for mineral elements accumulating differentiation of grassland plants in thedegradation succession: Cde(t)=Cb(1-exp(-αt)) and for that in the enclosed grassland: Cen(t)=Cbexp(-βt).4）Crops cultivation experiments and anti-hypoxic function of high iron contentThe crops cultivation experiments in Dabanshan-mountain, Lajishan-mountain and Xining well verify thespatial distribution pattern and the characteristic of vertical-banded spectrum of mineral elements in plants onthe north blank of Qinghai Lake. Meanwhile，these experiments provide some evidence for the “StarvationEffect” hypothesis.The distribution pattern of iron in barley and carrot in grassland plants on the north bank of Qinghai Lakeand Dabanshan-mountain and Lajishan-mountain area shows that high iron content in plants probably hasanti-hypoxic effect. For example, the content of Fe in the cultured highland barley in Dabanshan-mountain on2009are respectively93.60mg/kg,609.9mg/kg,799.1mg/kg,1360mg/kg and of which the altitude arerespectively2817m,2920m,3562m and3574m (P<0.05). Plants require more iron to increase theirrespiration in order to adapt the high altitude and the low oxygen levels which makes plants “hungry” for iron,under such circumstance, the iron accumulates. So, from this we come to a conclusion that low oxygen level inplateau air makes iron accumulate in plants.5）Characteristics of mineral elements in cultivation grassland on the north bank of Qinghai LakeThe characteristics of mineral elements in cultivation grassland are the same as that in natural grassland onthe north bank of Qinghai Lake. Each cultivation plant has a characteristic spectrum of mineral element andspatial distribution patterns of the content increases with altitude increase. For example, the content of Zn inplants of Elymus nutans in such places as Railway Side Slope, Sanjiaocheng Sheep Stud, West Town arerespectively30.07mg/kg,37.96mg/kg and42.01mg/kg and of which the altitude are respectively3216m,3220m and3287m (P<0.05).The content of mineral element in plants is lower on cultivation grassland than that on natural grassland.We use the “Starvation Effect” theory to explain this phenomenon; the “hungry” state is the endogenetic forcefor the accumulation of the mineral element on natural grassland.6）Cycles of mineral elements and its directive function of in production practiceThrough the biogeochemical cycle the mineral elements in soil can be taken up by grassland plants andaccumulate in their body forming the vertical-banded spectrum and the spatial distribution pattern which isconsistent with geomorphology and topography; then the mineral elements are transferred into human bodiesthrough food chain via plants and products from grassland animal husbandry. The mineral elements not onlyplay an important role in maintaining the balance of grassland ecosystem and the livestock-pasture system interms of their sustainable development but also have significant influence on the quality of livestock products.According to its characteristics and distribution patterns in space-time, we divide different grassland into different types. We also establish a mathmatical model for mineral elements in plants in grassland successionprocess. We can apply this theory to monitoring the supply of mineral elements in prataculture productionpractice so as to facilitate high-yield, high-quality produce. Consequently, meet the demands of sustainabledevelopment of prataculture and grassland animal husbandry. We should pay more attention on the“StarvationEffect”phenomenon when apply it in practice to avoid the illusion caused by mineral elements accumulationand differentiation behavior and provides mineral nutrition to plants scientifically.更多还原