1、B3 生 態(tài) 位,要 點(diǎn),有機(jī)體的生態(tài)位（niche）是它在它的環(huán)境中所處的位置，包括它發(fā)現(xiàn)的各種條件、所利用的資源和在那里的時(shí)間。,有機(jī)體的棲息地（habitat，或譯生境）是它所處的物理環(huán)境，例如，溫帶闊葉林。每一個(gè)棲息地提供許多生態(tài)位。,定義有機(jī)體生態(tài)位的每一個(gè)條件和資源，對于有機(jī)體能出現(xiàn)的空間提供一個(gè)維度。一起考慮所有維度，全面確定的有機(jī)體的生態(tài)位，是多維生態(tài)位空間，或“n-維超體積”。,生 態(tài) 位,棲 息 地,多維生態(tài)位空間,The ecological niche of an organism is the position it fills in its environment,

2、 comprising the conditions under which it is found, the resources it utilizes and the time it occurs there.,Key Notes,The habitat of an organism is the physical environment it is found in, for example, a temperate broad-leaved woodland. Each habitat provides.,Each condition or resource which defines

3、 the niche of an organism contributes one dimension to the space in which the organisms niche, and is the multidimensional niche space, orn-dimensional hypervolume.,B3 THE NICHE,Niche,Habitat,Multidimensional niche space,基礎(chǔ)生態(tài)位,在沒競爭和捕食條件下，有機(jī)體的生態(tài)位空間叫做基礎(chǔ)生態(tài)位（fundamental niche）。,相關(guān)主題,競爭的性質(zhì)（見I1） 資源分配（見I3）

4、 種內(nèi)競爭（見I2）,實(shí)際生態(tài)位,當(dāng)有競爭和捕食出現(xiàn)時(shí)，有機(jī)體所占有的生態(tài)位空間是實(shí)際生態(tài)位（realized niche），實(shí)際生態(tài)位始終是基礎(chǔ)生態(tài)位的一個(gè)子集。,The niche space an organism can fill in the absence of competition or predation is known as the fundamental niche.,The niche space occupied by an organism when competition and predation occur is the realized niche, wh

5、ich is always a subset of the fundamental niche.,The nature of competition (11) Resource partitioning(13) Intraspecific competition (12),Fundamental niche,Realized niche,Related topics,G1 資源與循環(huán),要 點(diǎn),營養(yǎng)物資源,群落以形形色色的方式獲得和損失營養(yǎng)物。機(jī)械風(fēng)化、化學(xué)腐蝕，特別是碳酸化作用，都是重要的過程。礦物質(zhì)在水中的簡單溶解也使?fàn)I養(yǎng)物從巖石和土壤中獲得成為可能。在水流中水可能攜帶著營養(yǎng)物，給下流地區(qū)提

6、供一個(gè)重要的資源。大氣也提供營養(yǎng)物，特別是二氧化碳和氮。大氣中其他營養(yǎng)物可能以濕降落（雨，雪和霧）和干降落（干燥期間的顆粒沉淀物）的方式回到群落。,G1 SOURCES AND CYCLES,Nutrients are gained and lost by communities in a variety of ways. Mechanical weathering, chemical weathering, particularly carbonation, are important processes. Simple dissolution of minerals in water al

7、so makes nutrients available from rock and soil. Water may carry nutrients in watercourses providing an important source in downstream areas. Atmospheric gases provide nutrient sources too, particularly carbon dioxide and nitrogen. Other nutrients from the atmosphere become available to communities

8、as wetfall (rain, snow and fog) and dryfall (settling of particles during dry periods).,Key Notes,Nutrient sources,陸地群落營 養(yǎng)物預(yù)算,有機(jī)體吸收的特定營養(yǎng)物微?？蛇B續(xù)地循環(huán)，直到營養(yǎng)物最終損失，這是通過許多過程中的任一個(gè)過程把營養(yǎng)物從系統(tǒng)中除去。營養(yǎng)物釋放可直接到達(dá)空氣或通過細(xì)菌作用（如甲烷）。對于許多元素來說，最重要的是丟失途徑是在水流中。營養(yǎng)物損失的其他途徑包括火災(zāi)、莊稼的收獲和森林砍伐。,A particular nutrient atom taken up by an

9、organism may cycle continuously until eventually the nutrient will be lost through any one of a number of processes that remove nutrients from the system. Release may be direct to the atmosphere or via bacterial action (as in the case of methane). For many elements, the most substantial pathway of l

10、oss is in streamflow. Other pathways of nutrient loss include fire, the harvesting of crops and deforestation.,Nutrient budgets in terrestrial communities,水生群落營養(yǎng)物預(yù)算,水生系統(tǒng)從水流中得到它們所需的大量營養(yǎng)物。在具有流出口的溪流、河流和湖泊中，水流出是個(gè)重要因素。通常，無機(jī)營養(yǎng)物置換階段與營養(yǎng)物固定在生物量中的時(shí)期是交替進(jìn)行的。浮游生物在湖泊中的營養(yǎng)物循環(huán)中起關(guān)鍵作用。海洋含有溫暖的表層水，生活著大多數(shù)的植物，還有冷的深層水（占總水容

11、量的90%）。表層水的營養(yǎng)物來源于兩種方面：（i）深層水的上涌流（組成物預(yù)算的95%以上），（ii）河流的輸入。,Aquatic systems obtain the bulk of their supply of nutrients from streamflow. In streams, rivers and lakes with a stream outflow, export in outgoing stream water is a major factor. Commonly, phases of fast inorganic nutrient displacement alter

12、nate with periods when the nutrient is locked in biomass. In lakes, plankton play a key role in nutrient cycling. Oceans contain warm suface waters, where most plant life is found and cold deep waters (which make up 90% of the total water volume). Nutrients in the suraface waters come from two sourc

13、es: (i) upwelling from deep water (which comprise over 95% of the nutrient budget),and (ii) river input.,Nutrient budgets in aquatic communities,地球化學(xué),地球上的化學(xué)元素庫存在于各種圈層（compartments）中：在巖石（巖圈）和土壤水、溪流、湖泊或海洋（可組合構(gòu)成水圈）中。在上述情況下，化學(xué)元素以無機(jī)形式存在。同時(shí)，生命有機(jī)體和已死亡及腐爛的有機(jī)物質(zhì)是在含有有機(jī)元素的圈層里。研究在這些區(qū)域內(nèi)發(fā)生的化學(xué)過程和圈層間元素的流動（通過生物過程產(chǎn)生了功

14、能性的改變和影響），稱為生物地球化學(xué)。,The pools of chemical elements on earth exist in various compartments: in rocks (the lithosphere), and soil water, streams, lakes or oceans (whish, combined, constitute the hydrosphere). In all these cases, the chemical elements exist in the inorganic form. In contrast, living or

15、ganisms and dead and decaying organic matter are compartments which contain elements in the organic form. Studies of the chemical processes occurring within these compartments and the flux of elements between them (which are fundamentally altered and affected by biotic processes) is termed biogeoche

16、mistry.,Geochemistry,全球生物地化循環(huán),陸地植物利用空氣中CO2作為光合作用的碳源，而水生植物使用溶解的碳酸化合物（水圈的碳）。呼吸作用把固定在光合產(chǎn)物中的碳，再釋放到氣圈和水圈的碳圈層中。在全球氮循環(huán)中，氣相是占優(yōu)勢的，其中，氮的固定和微生物的脫氮作用特別重要。磷主要儲存在土壤水、河流、湖泊、巖石和海洋沉淀物中，而硫儲存在大氣和巖石的組分中。,相關(guān)主題,植物與消費(fèi)者（G2） 土壤形成、特性和分類（G3節(jié)）初級和次級生產(chǎn)力（P2）,Terrestrial plants utilize atmospheric CO2 as their carbon source for ph

17、otosynthesis, whereas aquatic plants use dissolved carbonates (hydrosphere carbon). Respiration releases the carbon locked in photosynthetic products back to the atmospheric and hydrospheric carbon compartments. The atmospheric phase is predominant in the global nitrogen cycle, in which nitrogen fix

18、ation and denitrification by miocroorganisms are of particular importance. The main stocks of phosphorus occur in soil water, atmospheric and lithospheric components.,Geochemistry,Related topics,Plants and consumers (G2) Primary and secondary production Soil formation, properties and (P2) classifica

19、tion(G3),G3 土壤形成、特性和分類,要 點(diǎn),土壤形成,在陸地生態(tài)系統(tǒng)的底部是土壤：一薄層由生物和氣候改造的地球外殼。土壤提供了棲息地，具有營養(yǎng)物傳遞系統(tǒng)、再循環(huán)系統(tǒng)和廢物處理系統(tǒng)。土壤的研究稱為土壤學(xué)。土壤中的有機(jī)體參與了棲息地的形成，是土壤形成中構(gòu)成五個(gè)相互作用的因素之一；其他四個(gè)是氣候、地形、母質(zhì)和時(shí)間。土壤母質(zhì)的開始居住者通常是藍(lán)細(xì)菌，它能進(jìn)行光合作用和固定氮。高等植物形成后，土壤變化過程的多樣性產(chǎn)生了活的和死的細(xì)胞，和土壤有機(jī)物質(zhì)（SOM）的動態(tài)混合物。,G3 SOIL FORMATION, PROPERTIES AND CLASSIFICATION,Underlying t

20、errestrial ecosystems is the soil; a thin layer of the Earths crust that has been remade by life and weather, Soil provides habitats with a nutrient delivery system, a recycling system and a waste-disposal system. The study of soils is called pedology, Soil organisms participate in the formation of

21、the habitat and constitute one of the five interactive factors in soil formation; the other four are climate, topography, parent material and time. The initial colonizers of soil parent material are usually the cyanobcteria, capable of photosynthesis and nitrogen fixation. After higher vegetation ha

22、s become established, a variety of soil processes produces the dynamic mixture of living and dead cells, soil organic matter (SOM).,Key Notes,Soil formation,土壤剖面,土壤表面是死亡腐爛植物部分的枯枝落葉層，下面由完全不同的物質(zhì)組成的一層或多層。這些層可叫做“層”土層的形成是由于腐爛植物與礦物質(zhì)土壤的上層相混合。下面的亞土壤是土壤起始形成的地方，稱為母質(zhì)。這種分層的外貌叫做土壤剖面。土壤科學(xué)家認(rèn)為母質(zhì)以上的土層有三類：A、B和C層。這三層之

23、下是不變的母質(zhì)。這些以R層著稱。土壤剖面是重要生態(tài)系統(tǒng)過程中一個(gè)即時(shí)指標(biāo)。,At the surface of soil is a litter of dead or rotting plant parts, with one or more distinctly different layers underneath. These layers have come to be called horizons. Soil horizons form as rotting plant parts mix with the upper layers of the mineral soil. The

24、 subsoil underneath is the earth from which the soil was made and is called the parent material. This layered appearance is called the soil profile. Soil scientists recognize three kinds of soil horizon above the parent material; the A, B and C horizons. Under these three groups of horizons is the u

25、naltered parent material. These are known as R horizons. The soil profile is an instant indicator of important ecosystem processes.,The soil profile,主要分類： 大土壤群,在全球范圍上，大土壤群在土壤分類中是最容易制圖劃分的。土壤剖面的顏色和條帶用來區(qū)分大土壤群。全球土壤圖表示了一個(gè)粗略的大土壤群圖，與氣候和植被圖很相似。土壤勘測員是以農(nóng)田或郡縣部分為尺度來繪制土壤圖。通常只有大土壤群之一會存在。所使用的單位“土系”，是指從相同類型的母質(zhì)，通過相同

26、類型的結(jié)合過程而發(fā)展起來的一類土壤，它們的土層在它們的排列和一般特性上是完全相似的。,相關(guān)主題,演替（R1） 生態(tài)系統(tǒng)格局（S1）,Related topics,Succession (R1) Ecosystem patterns (S1),On a world scale, the great soil groups are the most easily mapped of any class in a soil classification. Color and banding of the soil profile distinguish the great soil groups.

27、World soil maps represent a rough plot of the great soil groups and are very similar to maps of climate or vegetation. Soil surveyors map soils on the scale of farm fields or parts of counties. Usually only one of the great soil groups will be present. The units used, soil series, are a group of soi

28、ls developed from the same kind of parent material, by the same generic combination of processes, and whose horizons are quite similar in their arrangement and general characteristics.,Primary classification: the great soil groups,I1 競爭的性質(zhì),要 點(diǎn),相互作用的 分類,個(gè)體或物種間的相互作用可以相互作用的機(jī)制和影響為基礎(chǔ)來分類。關(guān)鍵的種間相互作用是競爭、捕食、寄

29、生和互利共生，而主要的種內(nèi)相互作用是競爭、自相殘殺和利他主義。,I1 THE NATURE OF COMPETITION,Interactions between individuals and species can be classified on the basis of the effects and the mechanism of the interaction. The key interspecific interactions are competition, predation, parasitism and mutualism, whilst the main intra

30、specific interactions are competition, cannibalism and altruism.,Key Notes,Classifying interactions,競 爭,競爭是共同利用有限資源的個(gè)體間的相互作用，會降低競爭個(gè)體間的適合度。競爭即可在利用共同資源的物種間發(fā)生（種間競爭），也可在同種個(gè)體間發(fā)生（種內(nèi)競爭）。個(gè)體或物種的生態(tài)位（它所處的環(huán)境，利用的資源和它發(fā)生的時(shí)間）是決定該個(gè)體或物種與其他個(gè)體或物種競爭程度的關(guān)鍵。大范圍的生態(tài)位重疊一般導(dǎo)致激烈競爭。,Competition is an interaction among individuals

31、 utilizing a limited resource, resulting in reduced fitness in the competing individuals. Competition occurs both between species utilizing a shared resource (interspecific competition) and among members of a species (intraspecific competition). The niche of an individual or species (the conditions

32、under which it is found, the resources it utilizes and the time it occurs there) is critical in determining the degree of competition with other species or individuals. Large niche overlap generally results in intense competition.,Competition,種內(nèi)競爭,當(dāng)個(gè)體對資源的需要非常相似時(shí)，競爭會特別強(qiáng)烈。種內(nèi)競爭是生態(tài)學(xué)的一種主要影響力，是擴(kuò)散和領(lǐng)域現(xiàn)象的原因，

33、并且是種群通過密度制約過程進(jìn)行調(diào)節(jié)的主要原因。,種間競爭,種間競爭發(fā)生在利用同樣有限資源的兩物種之間。極少種能夠逃脫其他種與之競爭共同資源的影響。,Interspecific competition occurs between two species using the same limited resource. Very few species can escape from the effects of other species competing for the same resource.,Interspecific Competition,As individuals are

34、quite similar in their resource requirements, such competition may be particularly intense. Intraspecific competition is a major force in ecology and is responsible for phenomena such as dispersal and territoriality, as well as being the primary cause of population regulation via density-dependent p

35、rocesses.,Interspecific Competition,利用性競爭,競爭有兩種作用方式。在資源利用性競爭方式下，個(gè)體不直接相互作用，而是耗盡資源使供應(yīng)不足。由于可利用資源不足而造成適合度下降。,干擾性競爭,在干擾性競爭方式下，個(gè)體直接相互作用，在一些動物種類中，最明顯的通過打斗，也通過產(chǎn)生毒物（如植物異株克生）進(jìn)行競爭。在這種相互作用中“敗者”適合度下降，可能由于干擾（如受傷或死亡），也或許由于缺乏可用資源。,In interference competition, individuals interact directly, most obviously, in the ca

36、se of some animal species, by fighting, but also by producing toxins (e.g. plant allelopathy). Fitness reduction in the loser in such interactions may be due to the interference (e.e. injuries or death) as well as the lack of resource access.,Interfernce Competition,There are two ways in which compe

37、tition can operate. In exploitation competition, individuals only interact indirectly, by depleting the resource in short supply. Reduced fitness occurs due to a shortfall in resource availability.,Exploitation Competition,相關(guān)主題,生態(tài)位（B3） 資源分配（I3） 種內(nèi)競爭（I2）,競爭結(jié)果的 不對稱,競爭通常不均等的影響競爭者，一個(gè)體的競爭代價(jià)遠(yuǎn)高于另一個(gè)體。競爭殺死失敗

38、者是很普遍的，或通過掠奪資源或通過干擾。,Competition often unevenly affects competitors, such that the cost for one individual is far greater than for another. It is common for competition to kill the losers, either via exploitation or interference.,Asymmetry in the effects of Competition,Related topics,The niche (B3)

39、Resource partitioning (I3) Intraspecific competition (I2),I2 種內(nèi)競爭,要 點(diǎn),密度制約,密度制約描述適合度與種群大小之間的關(guān)系。種群調(diào)節(jié)的一個(gè)關(guān)鍵因子是負(fù)的密度制約，當(dāng)種群密度增加時(shí)，由于種內(nèi)競爭，使適合度下降。,I2 INTRASPECIFIC COMPETITION,Density dependence describes the relationship between fitness and population size. A key population regulatory factor is negative den

40、sity dependence, where declining fitness occurs as population density increases within a species due to intraspecific competition.,Key Notes,Density dependence,擴(kuò) 散,生物可通過擴(kuò)散離開種群密度高的地區(qū)，來對高水平的種內(nèi)競爭做出反應(yīng)。即使在生活周期內(nèi)大部分時(shí)間營固著生活的種類，也有一個(gè)可運(yùn)動的擴(kuò)散期。擴(kuò)散通常由種群內(nèi)較年輕的個(gè)體進(jìn)行，而在許多哺乳動物中雄性比雌性擴(kuò)散更多。,領(lǐng) 域 性,許多動物種（包括昆蟲、鳥類和哺乳動物）的個(gè)體或群體為

41、爭奪空間而競爭。保持領(lǐng)域邊界的個(gè)體間有積極的相互干擾行為。領(lǐng)域使其所有者受益，為對抗入侵者，保護(hù)領(lǐng)域所付出的代價(jià)，被增加的食物供應(yīng)、提高的交配成功率和降低的被捕食的危險(xiǎn)所帶來的價(jià)值超過。,Organisms can respond to high levels of intraspecific competition by dispersing away from the area of high population.density. Even in species that are sessile for most of the lifecycle, there is a mobile d

42、ispersal stage. Dispersal is often undertaken by the younger members of a population, whilst in many mammal species males disperse more than females to,Dispersal,In many animal species (including insects, birds and mammals) individuals or groups compete for areas of space. There is active interferen

43、ce between individuals to maintain the territory boundaries. Territoriality gives a benefit to the territory-holder, such that the costs of defending the territory against intruders are outweighed by advantages such as in creased food supplies, increased mating success and reduced predation risk.,Te

44、rritoriality,自 疏,固著生長的生物，包括植物，不能通過運(yùn)動逃避競爭，因此競爭中的失敗者死去在同樣年齡大小的植物群中，這種競爭結(jié)果使較少量的較大個(gè)體存活下來。這一過程叫做“自疏”。自疏導(dǎo)致密度與植物個(gè)體大小之間的關(guān)系，這在雙對數(shù)作圖時(shí)呈現(xiàn)典型的-3/2斜率。這種關(guān)系叫做Yoda-3/2自疏法則。,相關(guān)主題,生態(tài)位（B3） 競爭的性質(zhì)（I1）密度和密度制約（H3） 資源分配（I3）,Related topics,The niche (B3) The mature of competition (I1) Density and density dependence (H3) Resou

45、rce partitioning (I3),Sessile organisms, including plants, cannot escape competition by movement, and therefore the losers in the competitive battle die. In a group of plants of the same age, this results in fewer individuals of larger size surviving. This process is described as self-thinning. Self

46、-thinning results in a relationship between density and individual plant mass, which typically has a slope of 3/2on a log-log plot. This relationship is known as Yodas 3/2 law.,Self-thinning,J2 捕食行為和獵物反應(yīng),要 點(diǎn),獵物收益率,Given a choice between two potential prey types, a predator which is optimizing its ef

47、fort should choose the most profitable prey. Evidence from common shore crabs and pied wagtails demonstrates that prey of a size which return the greatest energy reward per unit time are preferred over smaller and larger individuals.,Key Notes,Profitability of prey,J2 PRED ATOR BEHAVIOR AND PREY RES

48、PNSE,獵物轉(zhuǎn)換,依據(jù)獵物種數(shù)量的多少，捕食者有時(shí)會轉(zhuǎn)換其選擇而捕食某一特定的獵物種。這時(shí)捕食者主要捕食優(yōu)勢種獵物而大大忽略其他獵物。,獵物密度影響 功能反應(yīng),一般認(rèn)為在高獵物密度下，捕食者的攝食率會增加，然后隨獵物飽和達(dá)到最大速度。這種關(guān)系稱為功能反應(yīng)，可能采用多種模式，傳統(tǒng)上分為三種類型：功能反應(yīng)I、II和III。,Predators may alter or switch their preference for a particular prey species depending on the abundance of that species, When this occurs,

49、 common prey are consumed super proportionately whilst less common prey are largely ignored.,Switching between prey types,It is generally expected that at high densities of prey, a predators consumption rate will increase and then flatten out as prey saturation occurs, this relationship is termed th

50、e functional response and may adopt different patterns, which can be stereotyped into three classes: functional responses I, II and III.,The effect of prey density functional responses,搜尋和處理,為得到食物，捕食者必須首先搜尋獵物，然后處理（抓住、加工和吃掉獵物）?？梢哉J(rèn)為捕食者食譜的寬度是由泛化種對策與特化種對策之間的權(quán)衡決定的。泛化種對策捕食者尋找多種獵物（相對容易），特化種對策捕食者尋找一類獵物，非常有效

51、的處理它。最佳覓食理論假定進(jìn)化會最優(yōu)化動物行為以使其獲得的能量效率最大，從而做出捕食者如何權(quán)衡搜尋與處理的預(yù)測。,To obtain food, a predator must first search for its prey and then handle (catch, process and eat) it. Diet width can be regarded as being determined by a balance between a generalist strategy of searching for a wide variey of prey (relatively

52、 easy) and a specialist strategy of searching for one type of prey and handling that very efficiently. Optimal foraging theory assumes that evolution will have optimized predator behavior to maximize the rate of energy gain and makes predictions about how we should expect predators to balance search

53、ing and handling.,Searching and handling,異質(zhì)性和獵物隱蔽處,實(shí)驗(yàn)室捕食者獵物實(shí)驗(yàn)表明在一個(gè)單純環(huán)境中，或（i）捕食者吃掉所有獵物個(gè)體，或（ii）捕食者種群消亡而獵物存活。然而，如果環(huán)境更為復(fù)雜，則一些獵物個(gè)體可能在獵物避難所中擺脫捕食，從而出現(xiàn)捕食者獵物的共存。由于生境斑塊在維持競爭種間共存中所起的作用（見I1）推論，環(huán)境異質(zhì)性很可能在允許捕食與獵物共存中具有關(guān)鍵的重要意義。,Predator-prey experiments in the laboratory indicate that in simple environment, either (

54、i) predators are able to consume all prey individuals, or (ii) the predator population becomes extinct and the prey survives. If, however, the habitat is more complex some prey refuges and coexistence between predators and prey may occur. In corollary with the role of habitat patchiness in maintaini

55、ng coexistence between competing species (see topic I1), environmental heterogeneity is likely to be of critical importance in allowing predators and prey to coexist.,Heterogeneity and prey refuges,理想自由分布,捕食者并不單獨(dú)對獵物的分布與密度做出反應(yīng)它們對與之競爭的捕食者的分布也會反應(yīng)。捕食者趨向于聚集在最有利可圖的斑塊中，但捕食者之間的擁擠會降低斑塊的有利度，直到移到另一塊不太擁擠的斑塊中去會更

56、好。理想自由分布理論認(rèn)為捕食者會在各分布區(qū)間移動，直到各區(qū)有利度相等。,Predators do not solely respond to the distribution and density of prey they may also respond to the distribution of competing predators. Predators will tend to aggregate in the most profitable patches, but predator crowding will reduce the patch profitability unt

57、il it is better to move to another less crowded patch. The ideal free distribution theory suggests that predators should move among sites until profitability is equal.,The ideal free distribution,植物防御,植物以兩種主要方式來保護(hù)自己免遭捕食：（i）毒性與差的味道，和（ii）防御結(jié)構(gòu)。在植物王國已發(fā)現(xiàn)大量的多種化學(xué)武器來保衛(wèi)植物免遭捕食和寄生者的進(jìn)攻。這些次生性化合物或直接有毒，或可降低植物的食物價(jià)值

58、，如降低動物腸道對植物葉組織蛋白的吸收。防御結(jié)構(gòu)在各種水平上都存在，從葉表面可陷住昆蟲及其他無脊椎動物的微小絨毛，到可阻止哺乳類草食動物的大型針刺。經(jīng)歷過落葉的植物，其次生化合物水平及防御結(jié)構(gòu)大小都會提高或“被誘導(dǎo)”。,相關(guān)主題,競爭的性質(zhì)（I1） 捕食的性質(zhì)（J1）,Related topics,The mature of competition (I1) The nature of predation J1),Plants defend themselves from predation in two main ways: (i) toxicity and unpalatablity, a

59、nd (ii) defensive structures. There is a vast variety of chemical ammunition found in the plant kingdom used to defend plants against attacks from predators and parasites. These secondary compounds may either be directly toxic or they may reduce the food value of the plant, for example, by reducing the availablity of the leaf tissue protein to the animal gut. Defensive structures exist on a variety of scales, from small hairs on the leaf surface which may trap insects and other invertebrates, to large spines which deter mammali