放牧對(duì)草地昆蟲多樣性的影響研究進(jìn)展

朱 慧,王德利,任炳忠

1 東北師范大學(xué)生命科學(xué)學(xué)院,長(zhǎng)春 130024 2 東北師范大學(xué)草地科學(xué)研究所,植被生態(tài)科學(xué)教育部重點(diǎn)實(shí)驗(yàn)室,長(zhǎng)春 130024

放牧對(duì)草地昆蟲多樣性的影響研究進(jìn)展

朱 慧1,2,*,王德利2,任炳忠1

1 東北師范大學(xué)生命科學(xué)學(xué)院,長(zhǎng)春 130024 2 東北師范大學(xué)草地科學(xué)研究所,植被生態(tài)科學(xué)教育部重點(diǎn)實(shí)驗(yàn)室,長(zhǎng)春 130024

在草地生態(tài)系統(tǒng)中,大型草食動(dòng)物放牧是重要的管理方式之一,對(duì)草地生物多樣性起著關(guān)鍵的驅(qū)動(dòng)作用。昆蟲是草地生態(tài)系統(tǒng)中生物多樣性的重要組成成分,對(duì)生態(tài)系統(tǒng)的食物網(wǎng)結(jié)構(gòu)以及其功能與穩(wěn)定性起著關(guān)鍵作用。已有研究結(jié)果表明,大型草食動(dòng)物與昆蟲存在密切聯(lián)系,放牧對(duì)草地昆蟲多樣性或有正向、或負(fù)向、或無明顯作用,這依賴于放牧管理方式、昆蟲類群以及草地類型。放牧必然通過直接(采食、踐踏或糞尿)或間接(植物群落組成或植被結(jié)構(gòu))作用對(duì)昆蟲多樣性產(chǎn)生顯著的影響。當(dāng)前,關(guān)于大型草食動(dòng)物放牧對(duì)草地昆蟲多樣性影響研究較多,但是,從研究系統(tǒng)性、深入性和延續(xù)性來說還存在一定問題。本文在綜述國內(nèi)外對(duì)放牧對(duì)草地昆蟲多樣性的影響研究基礎(chǔ)上,提出了今后的研究方向,對(duì)于理解放牧管理的草地昆蟲多樣性變化規(guī)律,以及為積極探索維持草地昆蟲多樣性的長(zhǎng)期有效的科學(xué)管理措施提供理論指導(dǎo)。

大型草食動(dòng)物;放牧;草地;昆蟲多樣性;作用機(jī)制

昆蟲是草地生態(tài)系統(tǒng)中動(dòng)物多樣性與生物量的重要組成部分,是食物鏈的關(guān)鍵環(huán)節(jié),在維持草地生態(tài)系統(tǒng)功能與穩(wěn)定性方面起著重要的作用[1]。然而,由于全球氣候變化、人類活動(dòng)和草地資源不合理利用,昆蟲多樣性面臨著部分昆蟲種類喪失,導(dǎo)致昆蟲多樣性減少[2],并且昆蟲多樣性減少的速度遠(yuǎn)遠(yuǎn)高于植物與脊椎動(dòng)物[3]。全球草地面積約為3.42 × 109hm2,約占陸地面積的40%,是地球上分布最為廣泛的陸地生態(tài)系統(tǒng)[4]。草地是被管理的生態(tài)系統(tǒng),大型草食動(dòng)物放牧是重要的管理方式之一。已有大量研究表明,放牧對(duì)草地生態(tài)系動(dòng)態(tài)有強(qiáng)烈的作用,例如改變植物多樣性、生產(chǎn)力等[5- 6]。由于草地昆蟲群落與植物群落密切聯(lián)系[7- 8],因此,放牧導(dǎo)致的植被變化必然引起昆蟲群落發(fā)生改變[9- 11]。目前,草地昆蟲多樣性如何響應(yīng)大型草食動(dòng)物放牧研究一直是生態(tài)學(xué)家和昆蟲學(xué)家關(guān)注的熱點(diǎn)問題,在昆蟲生態(tài)學(xué)中被日益強(qiáng)調(diào)。盡管對(duì)于放牧是如何影響昆蟲多樣性已有一定的認(rèn)識(shí),但對(duì)昆蟲多樣性如何響應(yīng)放牧的相關(guān)途徑與內(nèi)在機(jī)制仍然缺乏深入理解。本文結(jié)合已有的相關(guān)研究,對(duì)放牧影響草地昆蟲多樣性及其作用途徑進(jìn)行總結(jié),對(duì)于理解放牧干擾下草地昆蟲多樣性變化規(guī)律,以及維持草地生態(tài)系統(tǒng)的健康與可持續(xù)發(fā)展有重要的科學(xué)價(jià)值,同時(shí)為積極探索維持草地昆蟲多樣性的長(zhǎng)期有效的科學(xué)管理措施提供理論指導(dǎo)。

1 放牧對(duì)草地昆蟲多樣性的作用

圖1 大型草食動(dòng)物對(duì)草地昆蟲多樣性的作用結(jié)果及其影響因素Fig.1 Effects of large herbivore grazing on grassland insect diversity, and these effects strongly depends on different factors

根據(jù)目前的文獻(xiàn)報(bào)道,許多研究已經(jīng)證實(shí),大型草食動(dòng)物的放牧活動(dòng)對(duì)昆蟲產(chǎn)生重要作用[12-13],且作用結(jié)果存在不一致的研究結(jié)論(圖1)。一些研究工作表明,與無牧相比,昆蟲多樣性和數(shù)量在放牧樣地較小[14-16]。而另一些研究結(jié)果顯示,放牧增加昆蟲多樣性和數(shù)量[17-18]。研究者們已經(jīng)逐漸意識(shí)到這些研究結(jié)果之所以有明顯差異,可能是受到放牧強(qiáng)度限制。在放牧對(duì)昆蟲多樣性的影響研究中,更多研究都集中在放牧強(qiáng)度對(duì)昆蟲多樣性的作用[19],且多數(shù)研究結(jié)果證明,隨著放牧強(qiáng)度增加,昆蟲多樣性與數(shù)量逐漸增加[20-22],并且在適度放牧強(qiáng)度下維持較高的昆蟲物種豐富度[23]。放牧對(duì)草地昆蟲多樣性影響的另一個(gè)方面集中在放牧方式上。實(shí)驗(yàn)性研究發(fā)現(xiàn),與單一大型草食動(dòng)物種類放牧相比,兩種或兩種以上大型草食動(dòng)物混合放牧能夠促進(jìn)昆蟲多樣性[10],并且不同分類群的昆蟲數(shù)量在單一放牧和混合放牧條件下響應(yīng)也是存在明顯差異的[11]。同時(shí),還有研究結(jié)果表明,在進(jìn)行輪牧的放牧樣地中蝗蟲的物種豐富度最高,而在持續(xù)放牧的樣地中最低[24]。放牧對(duì)昆蟲多樣性的影響不僅僅限制在放牧強(qiáng)度和放牧方式上,放牧季節(jié)變化也能夠改變昆蟲多樣性對(duì)放牧的響應(yīng)。春季放牧?xí)r蝗蟲數(shù)量顯著低于秋季放牧[25],這可能與蝗蟲的生物學(xué)與生態(tài)學(xué)特性有關(guān)。

放牧對(duì)草地昆蟲多樣性的影響依賴于研究的昆蟲類群,即研究的昆蟲類群不同,也能使研究結(jié)論不一致[26]。例如,在放牧樣地,蝗蟲[27]、蛾類[28]、蝴蝶[29]多樣性減少,而甲蟲[30]和蠅類[31]的多樣性則增加。一般來說,蝗蟲、鱗翅目昆蟲的幼蟲為植食性昆蟲,大型草食動(dòng)物的采食后使這些昆蟲的食物資源受到嚴(yán)重影響,致使昆蟲因缺少充足的食物或無高質(zhì)量的食物而降低昆蟲生產(chǎn)性能,特別是生存率和繁殖能力降低[32]。由于昆蟲生產(chǎn)性能密切聯(lián)系著昆蟲種類和數(shù)量,從而減少這一類群昆蟲多樣性。在昆蟲群落中,甲蟲類群(更多為地面甲蟲)和蠅類昆蟲屬于腐生性昆蟲,在放牧草地生態(tài)系統(tǒng)中,主要以放牧動(dòng)物糞便和血液為食物。當(dāng)草地進(jìn)行放牧管理時(shí),由于放牧家畜的糞尿,必然能夠吸引部分糞食性甲蟲和吸食動(dòng)物血液的蠅類昆蟲,因此增加該類群的昆蟲種類及數(shù)量[33]。另外,還有研究證據(jù)表明,大型草食動(dòng)物的出現(xiàn)能夠增加壁虱數(shù)量[34],但是卻減少跳蚤數(shù)量[35]。

此外,草地昆蟲多樣性對(duì)放牧的響應(yīng)存在差異還可能由于草地類型不同。放牧影響蝗蟲多樣性的研究在不同草地類型中開展相應(yīng)的研究工作,但對(duì)研究結(jié)論進(jìn)行比較發(fā)現(xiàn),放牧對(duì)蝗蟲多樣性有或增加或減少的作用。例如,在典型草原中,放牧減少蝗蟲物種豐富度,而在荒漠草原中,放牧則使蝗蟲物種豐富度增加[27]。在美國高草草原(tallgrass prairie)和中國的草甸草原(meadow steppe)上的研究表明,放牧增加蝗蟲的物種多樣性和數(shù)量[11,14],但是在美國半干旱草地研究結(jié)果認(rèn)為放牧并沒有影響蝗蟲多樣性[13]。導(dǎo)致不一致研究結(jié)果的原因可能是不同的草地類型的植物群落存在較大差異,同時(shí)氣候條件(包括溫度和降水)也有不同程度的改變,蝗蟲對(duì)生境的長(zhǎng)期適應(yīng)使在不同草地類型中多樣性變化存在不一致性,放牧可能是蝗蟲多樣性響應(yīng)的不一致性變得更為復(fù)雜,因此使研究結(jié)論存在差異。

2 放牧對(duì)昆蟲多樣性的作用途徑

圖2 大型草食動(dòng)物放牧對(duì)昆蟲多樣性影響的直接和間接途徑的概念框架[36]Fig.2 A conceptual framework of the mechanistic pathways by which large herbivore grazing directly and indirectly affect insect diversity[36]

大型草食動(dòng)物放牧對(duì)草地昆蟲多樣性有著顯著作用,為了深入理解這種影響,放牧對(duì)昆蟲多樣性的作用途徑及其機(jī)制已經(jīng)成為本領(lǐng)域的另一重要科學(xué)問題。作為草地重要管理方式之一,放牧能夠通過采食(foraging)、踐踏(trampling)和糞尿排泄(faeces and urine)等途徑直接影響昆蟲多樣性,也能夠改變植物群落組成或者結(jié)構(gòu)間接作用于昆蟲多樣性(圖2)。

2.1 放牧對(duì)昆蟲多樣性的直接作用途徑

大型草食動(dòng)物對(duì)草地植物進(jìn)行采食,這種采食無意識(shí)地對(duì)生活在植物莖、葉上或者內(nèi)部的昆蟲多樣性產(chǎn)生影響。一般來說,一部分昆蟲易在植物的莖、葉上產(chǎn)卵或棲息,當(dāng)大型草食動(dòng)物采食時(shí),不能迅速移動(dòng)的昆蟲則會(huì)被大型草食動(dòng)物采食,從而減少該昆蟲數(shù)量減少[37-38]。若在放牧生境中這種昆蟲數(shù)量極少或較少,草食動(dòng)物的采食則導(dǎo)致這種昆蟲種類消失,從而減少放牧樣地的昆蟲多樣性。但是這一相關(guān)結(jié)論并未被通過實(shí)驗(yàn)性研究驗(yàn)證,只是通過模擬采食(例如刈割)實(shí)驗(yàn)得出大型草食動(dòng)物放牧能夠引起昆蟲較高的死亡率[39],從而降低昆蟲多樣性。因此,放牧動(dòng)物的采食對(duì)昆蟲多樣性的無意識(shí)地潛在作用需要更多的實(shí)驗(yàn)檢驗(yàn)。大型草食動(dòng)物放牧除了采食之外,踐踏對(duì)昆蟲多樣性也有著重要影響。放牧動(dòng)物在草地上采食的同時(shí),對(duì)草地也實(shí)施了踐踏作用,致使土壤容重、土壤含水量等受到嚴(yán)重影響[40],進(jìn)而改變昆蟲產(chǎn)卵選擇,特別是對(duì)把卵產(chǎn)在土壤中的昆蟲(如蝗蟲)。另外,由于踐踏作用使植物葉片容易凋落,把卵產(chǎn)在葉片的昆蟲因?yàn)闆]有合適的產(chǎn)卵位置也會(huì)另尋合適的生境及寄主繁殖后代。大型草食動(dòng)物踐踏通過對(duì)昆蟲生存、產(chǎn)卵等行為有著強(qiáng)烈影響[41-42],進(jìn)而改變昆蟲多樣性。但是,有關(guān)大型草食動(dòng)物踐踏對(duì)昆蟲多樣性的影響以及清晰的作用機(jī)制的研究較少。由于采食和踐踏作用實(shí)施野外控制實(shí)驗(yàn)較為困難,同時(shí)對(duì)昆蟲觀察方法(一些潛葉類昆蟲和一些土壤昆蟲)存在限制性因素,導(dǎo)致這方面的相關(guān)研究只停留在理論方面,并未進(jìn)行控制和野外實(shí)驗(yàn)進(jìn)行驗(yàn)證。

除采食和踐踏,大型草食動(dòng)物對(duì)昆蟲多樣性的直接作用途徑的另一重要方面是放牧動(dòng)物糞便的影響。在草地昆蟲群落中,有一部分昆蟲處于分解者地位,屬于腐食性昆蟲,即以動(dòng)物的尸體和糞便作為食物,因此,大型草食動(dòng)物糞便對(duì)這部分昆蟲有著潛在作用。已有研究表明,放牧對(duì)糞食性甲蟲多樣性和數(shù)量有明顯的促進(jìn)作用[43-44],但是,較高的放牧強(qiáng)度仍然對(duì)糞甲蟲昆蟲多樣性和數(shù)量有負(fù)作用[45-46]。盡管這些研究是研究放牧對(duì)糞食性甲蟲的作用,但都從改變植物群落結(jié)構(gòu)影響甲蟲多樣性,而沒有從大型草食動(dòng)物糞便角度進(jìn)行分析。從理論上可以表明,大型草食動(dòng)物能夠通過糞便提高腐蝕性昆蟲多樣性,但通過野外實(shí)驗(yàn)證明這一結(jié)論卻較少,其原因如下：第一,放牧動(dòng)物在采食過程是隨機(jī)的,致使糞便在草地上的分布有較大的異質(zhì)性,糞食性甲蟲多樣性的變化是否是因?yàn)榧S便的作用是很難分辨的。第二,應(yīng)用常規(guī)的地面糞食性甲蟲取樣方法(陷阱法trap-netting)存在一定弊端,不能較為準(zhǔn)確衡量甲蟲數(shù)量的變化,使實(shí)驗(yàn)的可操作性受到限制。因此,需要對(duì)取樣方法進(jìn)行改進(jìn),才能更好地理解放牧對(duì)糞食性昆蟲多樣性影響。

2.2 放牧對(duì)昆蟲多樣性的間接作用途徑

2.2.1 植物群落組成

生態(tài)學(xué)家關(guān)于放牧影響植物多樣性研究已經(jīng)有較長(zhǎng)的研究歷史[5,47-49],相應(yīng)的結(jié)論表明,大型草食動(dòng)物對(duì)植物多樣性或者有正向作用、或負(fù)向作用、或者無明顯作用,這依賴于不同的立地條件、不同的草地類型等因素。昆蟲屬于消費(fèi)者,必然與植物(生產(chǎn)者)有著緊密聯(lián)系[7],已有研究報(bào)道,隨著植物多樣性增加,昆蟲多樣性也隨之增大[8,50-51],這一結(jié)論不僅體現(xiàn)在植食性昆蟲上,對(duì)于捕食性昆蟲和寄生性昆蟲也是適用的[8,52]。鑒于昆蟲與植物的緊密關(guān)系,大型草食動(dòng)物能夠通過改變植物群落組成,特別是多樣性影響昆蟲多樣性和數(shù)量(圖2)。Joern在高草草原的研究表明,放牧可以通過改變植物物種豐富度從而增加蝗蟲的物種多樣性和數(shù)量[14]。Zhu等人在草甸草原的研究結(jié)果顯示,大型草食動(dòng)物對(duì)植物多樣性無影響,但是昆蟲多樣性卻發(fā)生較大變化[11]。因此,該研究認(rèn)為植物多樣性對(duì)放牧的響應(yīng)似乎不能作為昆蟲多樣性變化的一個(gè)合理的作用途徑。到目前為止,關(guān)于放牧通過改變植物多樣性影響昆蟲多樣性的研究并不多,可能是因?yàn)樵诜拍翖l件下,植物多樣性要經(jīng)過長(zhǎng)期的作用才能發(fā)生變化,進(jìn)而影響昆蟲多樣性,因此,若要驗(yàn)證這個(gè)途徑需要長(zhǎng)期放牧的實(shí)驗(yàn)性研究。

大型草食動(dòng)物也可以通過調(diào)節(jié)植物群落組成改變而影響昆蟲多樣性和數(shù)量。在溫帶的草地生態(tài)系統(tǒng)中研究發(fā)現(xiàn),大型草食動(dòng)物放牧使禾本科植物蓋度增加,由于食物資源增加,導(dǎo)致與禾本科植物密切聯(lián)系的植食性昆蟲物種豐富度增大[53]。在放牧條件下,如果放牧動(dòng)物偏食雜類草,放牧使開花的雜類草植物種類及蓋度減少,進(jìn)而對(duì)訪花昆蟲有負(fù)向作用[54]。這些結(jié)論表明,放牧能夠改變與昆蟲密切相關(guān)的植物功能群變化從而對(duì)昆蟲多樣性有著重要作用。此外,通過對(duì)不同放牧強(qiáng)度對(duì)蝗蟲數(shù)量研究發(fā)現(xiàn),在重度放牧強(qiáng)度下,蝗蟲數(shù)量顯著增加[22],這是由于大型草食動(dòng)物采食后蝗蟲的食物(植物)營養(yǎng)含量(N含量)降低,并且通過室內(nèi)試驗(yàn)得出植物營養(yǎng)含量增加,蝗蟲的生存率降低。但是也有相反的結(jié)論,研究認(rèn)為放牧使植物營養(yǎng)含量增加,從而引起昆蟲數(shù)量增大[55]。因此,大型草食動(dòng)物也能通過改變植物的特性(plant trait)——營養(yǎng)含量也能夠影響昆蟲的數(shù)量和多樣性。放牧通過影響植物群落組成改變草地昆蟲多樣性,更多由于影響了昆蟲的食物資源,包括食物數(shù)量和食物質(zhì)量。

2.2.2 植物群落結(jié)構(gòu)

大型草食動(dòng)物對(duì)植物有強(qiáng)烈的采食作用,由此改變植被高度和結(jié)構(gòu)的復(fù)雜性,這必然改變昆蟲的生境條件進(jìn)而作用于草地昆蟲多樣性(圖2)。對(duì)于昆蟲來說,生境結(jié)構(gòu)是影響其多樣性和數(shù)量的一個(gè)重要因素。由于大型草食動(dòng)物的選擇性采食,放牧能夠改變生境[56],特別昆蟲微生境的氣候條件。一方面,對(duì)于昆蟲來說,高和矮的植物群落提供的生境環(huán)境存在顯著差異,因此影響昆蟲多樣性和數(shù)量。例如,放牧后,植被變得較矮甚至暴露地表,這就使昆蟲的微生境變暖,特別是有較高的土壤溫度,有利于一些蝗蟲和蝴蝶的幼蟲發(fā)育[57-58],這樣的生境有利于把卵產(chǎn)在土壤中的昆蟲種類以及那些幼蟲喜好光照的昆蟲種類。另一方面,高的和密度大的植被也可以使昆蟲遇到低溫時(shí)作為一個(gè)溫度緩沖場(chǎng)所[59],或者也能作為昆蟲遇到極端環(huán)境(如干旱和洪水)的庇護(hù)所[60]。同時(shí),較高的植被能夠提供更多的食物資源以及較低被捕獲機(jī)率[61-62],因此,較高植被會(huì)比低矮植被容納更多的昆蟲種類。

在草地生態(tài)系統(tǒng)中,植物群落常常是異質(zhì)性分布的,其空間異質(zhì)性變化能夠影響昆蟲多樣性和數(shù)量。一方面,大型草食動(dòng)物由于食性選擇可以增加植被異質(zhì)性[11],同時(shí)也有相反的結(jié)論,即放牧也能使植被異質(zhì)性降低[63]。近期的研究表明,大型草食動(dòng)物放牧能夠通過改變植物高度異質(zhì)性進(jìn)而調(diào)節(jié)昆蟲多樣性[11],因此,關(guān)于昆蟲多樣性的驅(qū)動(dòng)因素研究中,除了關(guān)注植物多樣性與群落組成,應(yīng)對(duì)植被空間異質(zhì)性給予更多的認(rèn)識(shí)。Jerrentrup等人通過長(zhǎng)期的實(shí)驗(yàn)也證明在放牧影響昆蟲多樣性的因素中,植物群落異質(zhì)性是非常重要的[64]。但是,放牧引起的植被結(jié)構(gòu)異質(zhì)性將強(qiáng)烈影響昆蟲多樣性的實(shí)驗(yàn)性證據(jù)較少[65]。同時(shí),放牧對(duì)植被異質(zhì)性的作用是尺度依賴的[63]。例如,在小尺度范圍下,放牧能夠使植被同質(zhì)性增強(qiáng),而在大尺度范圍,則異質(zhì)性增強(qiáng)。然而,放牧對(duì)草地昆蟲多樣性的影響是否是尺度依賴的還未有相關(guān)研究證明,因此,要加深在不同空間尺度上放牧對(duì)植被異質(zhì)性的作用以及變化的異質(zhì)性與昆蟲多樣性關(guān)系研究,才能夠有更助于理解大型草食動(dòng)物對(duì)草地昆蟲多樣性的影響。

3 討論

第一,盡管大型草食動(dòng)物放牧對(duì)草地昆蟲多樣性的作用已有一定的理解和認(rèn)識(shí),但是由于放牧強(qiáng)度、放牧方式以及研究的昆蟲類群等方面,致使結(jié)果存在一定差異。同時(shí),關(guān)于放牧對(duì)草地昆蟲多樣性的影響都是在局域尺度上進(jìn)行,不同地區(qū)的植被類型、氣候以及地形等因素也會(huì)引起研究結(jié)果不一致。為了更好地、更深入的理解昆蟲多樣性對(duì)放牧的響應(yīng),需要在一個(gè)較大的尺度上(如區(qū)域尺度和全球尺度)進(jìn)行實(shí)驗(yàn)性或觀察性研究,使研究結(jié)論更為真實(shí)可靠。

第二,研究者更多是關(guān)注“大型草食動(dòng)物放牧是否對(duì)昆蟲多樣性產(chǎn)生作用”以及“作用結(jié)果如何”等問題,而對(duì)于放牧究竟如何調(diào)節(jié)昆蟲多樣性,即“大型草食動(dòng)物對(duì)草地昆蟲多樣性的作用途徑是什么”等問題迄今仍沒有一致性的結(jié)論,仍然需要更多的實(shí)驗(yàn)性研究工作進(jìn)行檢驗(yàn)。盡管很多研究都已經(jīng)證明,放牧可以通過植物物種組成、結(jié)構(gòu)以及空間異質(zhì)性間接改變昆蟲多樣性,但哪個(gè)因素起著主導(dǎo)作用卻缺乏相應(yīng)的研究工作,也就是,通過哪個(gè)途徑影響草地昆蟲多樣性的強(qiáng)度更大一些。同時(shí),有關(guān)放牧對(duì)昆蟲多樣性的直接作用研究較少,特別是大型草食動(dòng)物的采食、踐踏以及糞便如何影響昆蟲多樣性的具體機(jī)制并不清楚。

第三,在草地生態(tài)系統(tǒng)中關(guān)于食物網(wǎng)研究成為最近的科研工作者關(guān)注的焦點(diǎn)之一,昆蟲在食物網(wǎng)結(jié)構(gòu)中起著重要作用。大型草食動(dòng)物對(duì)草地生態(tài)系統(tǒng)中食物網(wǎng)研究還處于起步階段,放牧如何通過影響昆蟲多樣性改變草地生態(tài)系統(tǒng)食物網(wǎng)？是上行控制效應(yīng)還是下行控制效應(yīng)？因此,放牧條件下昆蟲多樣性變化對(duì)食物網(wǎng)結(jié)構(gòu)影響以及昆蟲發(fā)揮的重要作用將成為重要的研究方向。

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Effectsofgrazingbylargeherbivoresoninsectdiversityingrasslands

ZHU Hui1,2,*, WANG Deli2, REN Bingzhong1

1SchoolofLifeSciences,NortheastNormalUniversity,Changchun130024,China2KeyLaboratoryofVegetationEcology,MinistryofEducation,InstituteofGrasslandScience,NortheastNormalUniversity,Changchun130024,China

In grassland ecosystems, grazing by large herbivores is an important management tool, and plays a central role in driving biodiversity. Insects are important components of biodiversity in grasslands, and strongly affect food-web structure, as well as ecosystem functioning and stability. Many studies have shown that there are close relationships between large herbivores and insects. The effects of large herbivores on grasshopper species richness and abundance in grazed grassland ecosystems are inconsistent (positive effects, negative effects, and neutral effects), and the effect strongly depend on grazing management, insect guild, and grassland type. Grazing affects insect diversity both directly (foraging, trampling, and feces and urine) and indirectly (altered vegetation structure and plant community composition). Although a growing number of studies have shown that large herbivores can strongly affect insect diversity and abundance, greater additional efforts regarding the research on the systematisms, depth, and continuity of the response of insect diversity to grazing are still needed. This paper reviews the known effects of large herbivore grazing on insect diversity, and identifies a number of issues that remain poorly understood and require further research. The results of these studies could improve our understanding of changes in insect diversity, and provide theoretical support for the planning of management strategies aimed to conserve of insect diversity in grazed grassland ecosystems.

large herbivores; grazing; grassland; insect diversity; mechanisms

國家自然科學(xué)基金青年基金項(xiàng)目(31400345, 31230012)；中央高校基本科研業(yè)務(wù)經(jīng)費(fèi)項(xiàng)目(2412015KJ015)；植被生態(tài)科學(xué)教育部重點(diǎn)實(shí)驗(yàn)室開放課題(130028636)

2016- 08- 18; < class="emphasis_bold">網(wǎng)絡(luò)出版日期

日期:2017- 07- 11

*通訊作者Corresponding author.E-mail: zhuh824@nenu.edu.cn

10.5846/stxb201608181686

朱慧,王德利,任炳忠.放牧對(duì)草地昆蟲多樣性的影響研究進(jìn)展.生態(tài)學(xué)報(bào),2017,37(21):7368- 7374.

Zhu H, Wang D L, Ren B Z.Effects of grazing by large herbivores on insect diversity in grasslands.Acta Ecologica Sinica,2017,37(21):7368- 7374.