劉 超, 丁志鋒, 丁 平,*

1 浙江大學(xué)生命科學(xué)學(xué)院, 杭州 310058 2 廣東省昆蟲研究所 & 華南瀕危動(dòng)物研究所, 廣州 510260

千島湖陸橋島嶼鳥(niǎo)類集團(tuán)對(duì)棲息地片段化的敏感性及其季節(jié)變化

劉 超1, 丁志鋒2, 丁 平1,*

1 浙江大學(xué)生命科學(xué)學(xué)院, 杭州 310058 2 廣東省昆蟲研究所 & 華南瀕危動(dòng)物研究所, 廣州 510260

為探究千島湖陸橋島嶼不同鳥(niǎo)類集團(tuán)對(duì)棲息地片段化敏感性的差異和季節(jié)變化，于2009年4月—2012年1月鳥(niǎo)類繁殖季(4、5、6月)和冬季(11、12、1月)對(duì)千島湖41個(gè)陸橋島嶼鳥(niǎo)類集團(tuán)進(jìn)行了研究。結(jié)果表明，冬季雜食鳥(niǎo)對(duì)片段化敏感性高于食蟲鳥(niǎo)，繁殖季時(shí)二者無(wú)顯著差異，繁殖季和冬季時(shí)下層鳥(niǎo)對(duì)片段化敏感性均高于林冠鳥(niǎo)，冬季留鳥(niǎo)對(duì)片段化敏感性高于候鳥(niǎo)，繁殖季則無(wú)顯著差異。雜食鳥(niǎo)和留鳥(niǎo)對(duì)片段化敏感性存在季節(jié)差異，而食蟲鳥(niǎo)、林冠鳥(niǎo)、下層鳥(niǎo)和候鳥(niǎo)對(duì)片段化敏感性均無(wú)季節(jié)差異。不同鳥(niǎo)類集團(tuán)對(duì)棲息地片段化敏感性的差異和季節(jié)變化規(guī)律，有助于人們?cè)跅⒌毓芾砗捅Ｗo(hù)區(qū)設(shè)計(jì)時(shí)采取更有針對(duì)性的鳥(niǎo)類保護(hù)措施。

鳥(niǎo)類集團(tuán); 棲息地片段化; 敏感性; 季節(jié)差異

棲息地喪失和片段化是導(dǎo)致物種多樣性喪失的最重要因素[1-2]。棲息地片段化后，各種片段化效應(yīng)將導(dǎo)致物種多樣性的喪失[3-5]，進(jìn)而影響生物群落物種組成與多樣性及其動(dòng)態(tài)[5-8]。因此，深入了解棲息地片段化對(duì)物種多樣性和群落的影響成為當(dāng)今生態(tài)學(xué)與保護(hù)生物學(xué)學(xué)領(lǐng)域的核心問(wèn)題之一[3,5]。鳥(niǎo)類作為人類最為關(guān)注的生物類群之一，棲息地片段化對(duì)其多樣性與群落的影響亦已引起鳥(niǎo)類學(xué)家的廣泛關(guān)注[6,9-13]。

集團(tuán)是指一群具有相似的方式探索和利用同類環(huán)境資源的物種集合和群落功能單位[14]。作為群落功能群的重要類型，通過(guò)鳥(niǎo)類群落集團(tuán)劃分有助于從功能群的角度探究鳥(niǎo)類物種在群落中的功能定位[15-16]，分析群落內(nèi)部物種相互關(guān)系，評(píng)估物種對(duì)資源和環(huán)境變化的響應(yīng)[17-18]。集團(tuán)已成為鳥(niǎo)類群落功能群研究的常用方法[19-21]，從集團(tuán)角度揭示片段效應(yīng)亦已成為了片段化研究的熱點(diǎn)之一[22]。

棲息地片段化不僅影響鳥(niǎo)類的物種多樣性和和豐富度，也影響著鳥(niǎo)類的群落及其集團(tuán)結(jié)構(gòu)。不同鳥(niǎo)類對(duì)片段化的敏感性不同，使得不同鳥(niǎo)類集團(tuán)對(duì)片段化的敏感性亦存在差異[23]。已有研究顯示，候鳥(niǎo)和留鳥(niǎo)[16]、核心種和邊緣種[8]、不同食性[24-27]和取食基底集團(tuán)[28-31]等不同類型和功能群的鳥(niǎo)類對(duì)棲息地片段化的響應(yīng)均呈現(xiàn)不同的規(guī)律。然而，以往的研究大部分是在陸地棲息地島嶼中進(jìn)行，而鳥(niǎo)類群落集團(tuán)在陸橋島嶼和陸地棲息地島嶼間對(duì)片段化的敏感性和響應(yīng)是否存在相同的模式需進(jìn)一步驗(yàn)證。

因大壩建設(shè)形成的人工湖泊型陸橋島嶼，其形成時(shí)間較為一致、隔離基質(zhì)單一、邊緣分明，排除很多其它因素的干擾，因而是較為理想的研究棲息地片段化問(wèn)題平臺(tái)[32-33]。為此，本研究以千島湖陸橋島嶼為研究平臺(tái)，選擇食性、取食基底和居留類型等功能性狀將鳥(niǎo)類進(jìn)行集團(tuán)劃分，研究鳥(niǎo)類集團(tuán)的物種豐富度和島嶼面積關(guān)系、鳥(niǎo)類集團(tuán)對(duì)棲息地片段化的敏感性與季節(jié)變化，以及不同鳥(niǎo)類集團(tuán)敏感性差異及其季節(jié)變化的機(jī)制。

1 研究地區(qū)和方法

1.1 研究地區(qū)

千島湖位于浙江省淳安縣境內(nèi)，是1959年新安江水庫(kù)建成后形成的擁有眾多陸橋島嶼的人工湖泊。在最高水位108 m時(shí)，面積大于0.25 hm2的島嶼有1078個(gè)[34]。千島湖地區(qū)為典型的亞熱帶季風(fēng)型氣候，四季分明，夏季溫暖濕潤(rùn)，冬季寒冷少雨，年平均氣溫為17.0℃，年平均降水量為1430 mm。Hu等[7]對(duì)該地區(qū)植物調(diào)查共記錄野生維管束植物456種，其中喬木120種，灌木61種，草本232種，藤本43種。島嶼間植被類型比較一致，喬木以馬尾松(Pinusmassoniana)為主，還有苦櫧(Castanopsissclerophylla)、柏樹(shù)(Platycladusorientalis)等；灌木層主要為滿山紅(Rhododendronmariesii)、鹽膚木(Rhuschinensis)、黃檀(Dalbergiaodrifera)、檵木(Loropetalumchinese)等；草本主要為芒萁(Dicranopterisdichotoma)，夾雜一些矮竹叢。

1.2 研究方法

1.2.1 島嶼參數(shù)獲取

根據(jù)島嶼面積、隔離度(距大陸的最近距離)梯度選取41個(gè)調(diào)查樣島，測(cè)定島嶼面積、隔離度等，并計(jì)算島嶼形狀指數(shù)(SI)[34]。SI=P/[2×(π×A)0.5]，式中P為島嶼周長(zhǎng)，A為島嶼面積。將島嶼植物生境劃分為7個(gè)類型：針葉林、闊葉林、針闊混交林、竹林、灌叢、雜草和農(nóng)田[35]，以島嶼上所包含植物生境類型的數(shù)量作為生境豐富度[36]。具體參數(shù)見(jiàn)附表1。

1.2.2 鳥(niǎo)類群落調(diào)查方法

鳥(niǎo)類調(diào)查采用樣線法進(jìn)行分層隨機(jī)取樣調(diào)查[37]。根據(jù)島嶼面積按照一定比例確定島嶼樣線長(zhǎng)度、數(shù)量(41個(gè)島嶼樣線長(zhǎng)度及數(shù)量見(jiàn)附表1)，每個(gè)季節(jié)(繁殖季和冬季)對(duì)每個(gè)島嶼各調(diào)查9遍，調(diào)查強(qiáng)度能確保有效記錄各島嶼上的鳥(niǎo)類。于2009年4月—2012年1月鳥(niǎo)類繁殖季(4、5、6月)和冬季(11、12、1月)沿著各島嶼樣線行走，沿途記錄樣線兩側(cè)25m范圍內(nèi)看到或聽(tīng)到鳥(niǎo)類的名稱、數(shù)量及行為等數(shù)據(jù)。調(diào)查選擇在晴朗、無(wú)風(fēng)的天氣條件下進(jìn)行，根據(jù)鳥(niǎo)類活動(dòng)規(guī)律確定調(diào)查時(shí)間。調(diào)查選擇在日出和日落前后鳥(niǎo)類活動(dòng)高峰期進(jìn)行，日出前半個(gè)小時(shí)開(kāi)始，到11:00結(jié)束；15:00開(kāi)始，日落前半個(gè)小時(shí)結(jié)束，具體調(diào)查時(shí)間參考光線強(qiáng)弱和實(shí)際鳥(niǎo)況進(jìn)行調(diào)整。每個(gè)研究島嶼由不同調(diào)查者完成且每次調(diào)查順序隨機(jī)選擇，以盡量減少人為因素和實(shí)驗(yàn)設(shè)計(jì)產(chǎn)生的誤差，確保鳥(niǎo)類調(diào)查的科學(xué)性和準(zhǔn)確性。

1.2.3 鳥(niǎo)類集團(tuán)的劃分

通過(guò)野外觀察并參考O′Connell 等[38]和Canterbury等[39]的研究方法，結(jié)合《浙江動(dòng)物志·鳥(niǎo)類》[40]對(duì)鳥(niǎo)類的詳細(xì)介紹，將所有調(diào)查記錄的鳥(niǎo)類按照以下三類指標(biāo)進(jìn)行集團(tuán)劃分：食物類型、取食基底和居留類型。具體劃分見(jiàn)表1。由于物種豐富度高于3的鳥(niǎo)類集團(tuán)才具有一定統(tǒng)計(jì)功效，本研究?jī)H分析島嶼上物種豐富度大于3的鳥(niǎo)類集團(tuán)：留鳥(niǎo)、候鳥(niǎo)，食蟲鳥(niǎo)、雜食鳥(niǎo)，林下層取食鳥(niǎo)、林冠層取食鳥(niǎo)。研究所記錄的全部鳥(niǎo)類所屬集團(tuán)詳細(xì)情況見(jiàn)附表2。

1.2.4 鳥(niǎo)類集團(tuán)對(duì)棲息地片段化敏感性的比較

經(jīng)典的島嶼生物地理學(xué)理論認(rèn)為，物種豐富度面積關(guān)系能較好闡明片段化棲息地中物種豐富度與斑塊面積之間的變化關(guān)系，物種豐富度隨著島嶼面積的增加而增加，隨著隔離度的增加而減少，而物種豐富度面積關(guān)系曲線的斜率z值大小可以衡量物種對(duì)棲息地片段化的敏感性，z值越大，物種對(duì)片段化越敏感，反之則對(duì)片段化越不敏感[41-43]。采用Zar[44]的方法對(duì)不同回歸方程z值差異性進(jìn)行檢驗(yàn)。該方法統(tǒng)計(jì)表達(dá)式為td=(b1-b2) /Sb1-b2,式中b1和b2為回歸斜率，Sb1-b2為回歸斜率間的標(biāo)準(zhǔn)誤。然后通過(guò)t分布t(td,df)得到概率分布值p, df表示自由度。所有顯著性差異設(shè)定若P<0.05，則兩個(gè)z值之間存在顯著差異，表明不同鳥(niǎo)類集團(tuán)敏感性存在顯著差異，反之，則敏感性無(wú)顯著差別。

2 數(shù)據(jù)處理

根據(jù)丁志鋒[45]對(duì)各島嶼參數(shù)(面積、隔離度、PAR、形狀指數(shù)、棲息地多樣性、植物物種豐富度)所作的Pearson相關(guān)性檢驗(yàn)和共線性分析結(jié)果，島嶼形狀指數(shù)和生境多樣性與島嶼面積呈現(xiàn)很強(qiáng)正相關(guān)(r> 0.8)，將其剔除以避免對(duì)統(tǒng)計(jì)結(jié)果的干擾[46]。且所有參數(shù)VIF值小于10，表明共線性不影響最終結(jié)果。本研究選擇解釋度較高的冪函數(shù)模型(logS=logc+z×logA，式中S為島嶼物種豐富度，A為島嶼面積，c和z均為常數(shù))研究鳥(niǎo)類集團(tuán)物種豐富度與島嶼面積之間的關(guān)系。統(tǒng)計(jì)分析采用R software 2.13和SPSS19.0進(jìn)行，繪圖在Excel 2007中完成。

3 結(jié)果

3.1 不同季節(jié)同一鳥(niǎo)類集團(tuán)的敏感性

繁殖季共記錄61種鳥(niǎo)，冬季共記錄52種鳥(niǎo)。繁殖季和冬季調(diào)查記錄的不同鳥(niǎo)類集團(tuán)物種豐富度見(jiàn)表1。繁殖季和冬季各鳥(niǎo)類集團(tuán)物種豐富度島嶼面積關(guān)系z(mì)值在0.07—0.21之間(圖1，圖2)。雜食鳥(niǎo)和留鳥(niǎo)對(duì)片段化敏感性存在季節(jié)差異(P<0.05)，食蟲鳥(niǎo)、林冠鳥(niǎo)、下層鳥(niǎo)和候鳥(niǎo)對(duì)片段化敏感性則無(wú)季節(jié)差異(P>0.05)。

圖1 所有鳥(niǎo)類(a)、繁殖季(b)和冬季(c)鳥(niǎo)類物種豐富度面積關(guān)系Fig.1 Species-area relationship of all birds(a), birds in breeding(b) and winter(c) seasons

3.2 同一季節(jié)不同鳥(niǎo)類集團(tuán)的敏感性

在繁殖季，島嶼所有鳥(niǎo)類物種豐富度與島嶼面積關(guān)系z(mì)值為0.11，冬季所有鳥(niǎo)類物種豐富度與島嶼面積關(guān)系z(mì)值為0.14，兩個(gè)季節(jié)全部鳥(niǎo)類物種豐富度面積關(guān)系z(mì)值為0.10，三者之間無(wú)顯著差異(P> 0.05)。所有鳥(niǎo)類集團(tuán)中，冬季雜食鳥(niǎo)對(duì)片段化敏感性高于食蟲鳥(niǎo)(P< 0.05)，繁殖季時(shí)二者無(wú)顯著差異(P> 0.05)，繁殖季和冬季下層鳥(niǎo)對(duì)片段化敏感性均高于林冠鳥(niǎo)(P<0.05)，冬季留鳥(niǎo)對(duì)片段化敏感性高于候鳥(niǎo)(P<0.05)，繁殖季則無(wú)顯著差異(P> 0.05)。

4.1 不同季節(jié)同一鳥(niǎo)類集團(tuán)的敏感性差異

研究結(jié)果顯示，千島湖陸橋島嶼上繁殖季和冬季各自包含的所有物種對(duì)棲息地片段化的敏感性無(wú)差異；但不同食性、取食基底和居留型鳥(niǎo)類集團(tuán)對(duì)棲息地片段化的敏感性存在差異，部分集團(tuán)的敏感性存在季節(jié)變化。鳥(niǎo)類群落和各鳥(niǎo)類集團(tuán)對(duì)片段化敏感性表現(xiàn)出不同規(guī)律，這也表明通過(guò)更加細(xì)致的集團(tuán)劃分深入探究鳥(niǎo)類群落動(dòng)態(tài)變化規(guī)律是有必要的。各鳥(niǎo)類集團(tuán)的物種豐富度面積關(guān)系z(mì)值相較于陸地片段化棲息地中研究結(jié)果偏低，這可能和本地區(qū)島嶼隔離度較小從而導(dǎo)致鳥(niǎo)類較高遷移頻繁及較低滅絕速率有關(guān)[47-48]。調(diào)查發(fā)現(xiàn)，紅頭長(zhǎng)尾山雀(Aegithalosconcinnus)和大山雀(Parusmajor)等體型小、飛行能力相對(duì)有限的鳥(niǎo)類幾乎在所有島嶼都有分布，且在島嶼間頻繁遷移，可見(jiàn)隔離度對(duì)其影響有限。

表1 鳥(niǎo)類集團(tuán)劃分及繁殖季、冬季各集團(tuán)物種豐富度(“/”前半部分：繁殖季物種豐富度，”/”后半部分：冬季物種豐富度)

圖2 繁殖季(a)和冬季(b)不同食性、取食基底、居留型的鳥(niǎo)類集團(tuán)物種豐富度面積關(guān)系Fig.2 Relationships between species richness of bird guild with different dietary type、foraging strata、migratory status and island area in the breeding(a) and winter(b) seasons

4 討論

食物是影響鳥(niǎo)類對(duì)片段化敏感性的重要因素，食物資源獲得情況影響鳥(niǎo)類取食效率和繁殖成功率。此外，鳥(niǎo)類食性、覓食位置、特定環(huán)境依賴性、擴(kuò)散能力和棲息地特征也會(huì)對(duì)敏感性產(chǎn)生影響[31]。Zannette等[49]的研究表明，面積小的森林斑塊中鳥(niǎo)類食物資源相對(duì)短缺。千島湖陸橋島嶼面積較小，植被類型較為單一，且該地區(qū)氣候存在明顯的季節(jié)變化，食物的種類和數(shù)量會(huì)產(chǎn)生季節(jié)波動(dòng)，引發(fā)各鳥(niǎo)類集團(tuán)對(duì)片段化敏感性的不同程度響應(yīng)。

以往在陸地片段化斑塊中的研究表明，食蟲鳥(niǎo)、下層鳥(niǎo)等集團(tuán)往往對(duì)片段化敏感性更高，敏感性強(qiáng)弱也更容易受到影響[29,50]。對(duì)千島湖陸橋島嶼鳥(niǎo)類集團(tuán)敏感性研究發(fā)現(xiàn)，雜食鳥(niǎo)和留鳥(niǎo)對(duì)棲息地片段化的敏感性存在季節(jié)差異，其敏感性時(shí)間波動(dòng)大，而其它鳥(niǎo)類集團(tuán)未表現(xiàn)出季節(jié)差異。本地區(qū)雜食鳥(niǎo)和留鳥(niǎo)中，以白頭鵯(Pycnonotussinensis)、黑鵯(Hypsipetesleucocephalus)等鵯類常見(jiàn)，這些鳥(niǎo)對(duì)本地環(huán)境適應(yīng)性強(qiáng)、分布廣，在資源呈現(xiàn)季節(jié)變化時(shí)，這些鳥(niǎo)在大陸和島嶼間分布呈現(xiàn)季節(jié)性規(guī)律，表現(xiàn)出敏感性的季節(jié)差異。這一規(guī)律與陸地片段化棲息地中鳥(niǎo)類集團(tuán)呈現(xiàn)的規(guī)律不同，造成這種差異的原因可能是多方面的，可能與千島湖陸橋島嶼面積較小、植被類型較為單一以及本地區(qū)氣候存在顯著的季節(jié)分化有關(guān)。小型斑塊中的食物資源季節(jié)性波動(dòng)，冬季時(shí)食物資源相對(duì)匱乏，部分集團(tuán)敏感性會(huì)隨之上升。

陸地斑塊普遍具有面積及隔離度大、邊界模糊、隔離基質(zhì)復(fù)雜多樣、斑塊內(nèi)部植被類型多樣等特征，而陸橋島嶼面積和隔離度較小、邊界清晰、隔離基質(zhì)單一、植被類型簡(jiǎn)單。兩類生態(tài)系統(tǒng)具有完全不同的特點(diǎn)，因而在片段化研究中常常呈現(xiàn)不同的規(guī)律。以往的研究表明，千島湖陸橋島嶼植物、蜥蜴、小型獸類、鳥(niǎo)類等不同類群的分布具有不同于陸地斑塊的格局和決定機(jī)制[36,51]，此次對(duì)鳥(niǎo)類集團(tuán)敏感性季節(jié)變化規(guī)律的研究進(jìn)一步揭示：陸橋島嶼鳥(niǎo)類集團(tuán)對(duì)片段化敏感性及變化具有不同于陸地斑塊的規(guī)律。這種差異在保護(hù)區(qū)建設(shè)和棲息地管理時(shí)需要考慮。

4.2 同一季節(jié)不同鳥(niǎo)類集團(tuán)的敏感性差異

以往對(duì)陸地斑塊棲息中鳥(niǎo)類食性集團(tuán)研究表明，食蟲鳥(niǎo)比雜食鳥(niǎo)對(duì)片段化的敏感性更高。這與食蟲鳥(niǎo)對(duì)食物需求更加固定有關(guān)，也和它們對(duì)棲息地要求更高有關(guān)[25,52]。本研究結(jié)果恰恰相反，繁殖季時(shí)二者對(duì)片段化的敏感性無(wú)顯著差異，冬季雜食鳥(niǎo)對(duì)片段化的敏感性甚至高于食蟲鳥(niǎo)。在小型陸橋島嶼片段化棲息地中，資源有限會(huì)導(dǎo)致鳥(niǎo)類種間競(jìng)爭(zhēng)加劇，雜食鳥(niǎo)的食性占據(jù)生態(tài)位更寬，物種彼此間更易產(chǎn)生生態(tài)位重疊或擠壓，導(dǎo)致競(jìng)爭(zhēng)加劇、鳥(niǎo)類集團(tuán)敏感性增加。食蟲鳥(niǎo)相比于雜食鳥(niǎo)，可選擇食物種類少，但陸橋島嶼特定的環(huán)境使得其在島嶼間能頻繁遷移獲得食物，在一定程度上也削弱了食蟲鳥(niǎo)的敏感性。

研究發(fā)現(xiàn)，無(wú)論在繁殖季或冬季，下層鳥(niǎo)比林冠鳥(niǎo)對(duì)棲息地片段化都更加敏感，這和陸地斑塊中關(guān)于鳥(niǎo)類集團(tuán)的研究結(jié)果相同。這可能與下層鳥(niǎo)在島嶼間擴(kuò)散能力較差有關(guān)，而林冠鳥(niǎo)的活動(dòng)特點(diǎn)使得其具備較強(qiáng)穿越林層能力，擴(kuò)散能力更強(qiáng)。因而相比于下層鳥(niǎo)，林冠鳥(niǎo)對(duì)片段化不敏感[29-31]。

關(guān)于留鳥(niǎo)和候鳥(niǎo)對(duì)棲息地片段化的響應(yīng)，多數(shù)研究表明，片段化對(duì)留鳥(niǎo)的影響要大于候鳥(niǎo)，留鳥(niǎo)對(duì)片段化的敏感性高于候鳥(niǎo)。這與留鳥(niǎo)常年生活在某個(gè)區(qū)域從而對(duì)棲息地有特定要求有關(guān)，也和其對(duì)本地營(yíng)巢及食物資源要求較高有關(guān)[16,53]。留鳥(niǎo)和候鳥(niǎo)可能受到彼此正的相互作用影響，這種機(jī)制被稱為“異種特異性吸引”。候鳥(niǎo)選擇棲息地可能會(huì)參考留鳥(niǎo)的選擇，使得二者對(duì)棲息地片段化的敏感性更加相近，這在繁殖季有時(shí)更加明顯[54]。千島湖陸橋島嶼留鳥(niǎo)和候鳥(niǎo)集團(tuán)在繁殖季時(shí)對(duì)片段化敏感性無(wú)顯著差異，而在冬季時(shí)留鳥(niǎo)對(duì)片段化敏感性更高，不同季節(jié)可能存在不同機(jī)制影響留鳥(niǎo)和候鳥(niǎo)對(duì)片段化敏感性的相對(duì)強(qiáng)弱。

致謝：斯幸峰、宋虓、丁文勇對(duì)實(shí)驗(yàn)數(shù)據(jù)處理提供幫助，王思宇、吳強(qiáng)、陳傳武等參與野外工作，淳安縣林業(yè)局和千島湖國(guó)家森林公園管理部門對(duì)研究給予支持，特此致謝。

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Seasonal changes in sensitivity of bird guilds to habitat fragmentation on land-bridge islands in the Thousand Island Lake, China

LIU Chao1, DING Zhifeng2, DING Ping1,*

1CollegeofLifeSciences,ZhejiangUniversity,Hangzhou310058,China2GuangdongEntomologicalInstitute&SouthChinaInstituteofEndangeredAnimals,Guangzhou510260,China

Habitat loss and fragmentation seriously threaten global species diversity. Understanding the impact on species and communities is a core issue for ecology and conservation biology. A guild acts as a functional unit within a community. Bird guild research can help to analyze relationships among different species and evaluate their responses to habitat fragmentation. Much research has focused on bird guilds in terrestrial fragments, while other fragmented systems, such as land-bridge islands, draw relatively less attention. Because different systems tend to display different geological and ecological patterns, we needed to verify whether terrestrial fragments and land-bridge islands share common patterns of response to habitat fragmentation. The land-bridge islands in the Thousand Island Lake, which were created by dam construction, are an ideal platform for the study of habitat fragmentation. To test bird sensitivity to habitat fragmentation across seasons, we conducted bird guild studies on 41 land-bridge islands in the Thousand Island Lake during the breeding season (April-June) and winter season (November-January) of each year between April 2009, and January 2012. We classified birds into guilds according to dietary type, foraging strata, and migratory status. We used an equation with logarithmic transformation from island biogeography,S=CAz, to clarify the relationship between bird guild species richness and island fragment area. In this equation,Srepresents species richness of each bird guild,Arepresents island area,Cis a constant, andzis the slope of the species-area curve. This variable can be considered a measurement of sensitivity to habitat fragmentation. The bigger the value ofz, the greater the sensitivity of the bird guild. We extracted and compared the slope of each species-area relationship curve (zvalue) to determine whether there exists significant variation in sensitivity to habitat fragmentation among the different bird guilds. Our research indicated that omnivorous birds were more sensitive to habitat fragmentation than insectivores during the winter season, while no significant difference was found for the breeding season. Understory birds were more sensitive to habitat fragmentation than canopy birds, both in breeding and winter seasons. Resident birds were more sensitive than migrants in winter, while no significant difference between them were observed in the breeding season. Both omnivorous and resident birds showed seasonal changes in their sensitivity to fragmentation. Other guilds, including insectivorous birds, canopy birds, understory birds, and migratory birds, showed no significant seasonal changes. Previous studies conducted in terrestrial fragments support our findings that responses of bird guilds to habitat fragmentation differ and that seasonal changes in the responses to habitat fragmentation do exist. These results may aid in the effective management of bird habitats and in the design of nature reserves. Future studies may focus on other bird guild types and determine if differences in responses to habitat fragmentation occur at a larger temporal scale.

bird guild; habitat fragmentation; sensitivity; seasonal changes

附表1 41個(gè)研究島嶼參數(shù)

國(guó)家自然科學(xué)基金項(xiàng)目(31170397, 31210103908)

2014-06-26; < class="emphasis_bold">網(wǎng)絡(luò)出版日期:

日期:2014-12-18

10.5846/stxb201406261319

*通訊作者Corresponding author.E-mail: dingping@zju.edu.cn

劉超, 丁志鋒, 丁平.千島湖陸橋島嶼鳥(niǎo)類集團(tuán)對(duì)棲息地片段化的敏感性及其季節(jié)變化.生態(tài)學(xué)報(bào),2015,35(20):6759-6768.

Liu C, Ding Z F, Ding P.Seasonal changes in sensitivity of bird guilds to habitat fragmentation on land-bridge islands in the Thousand Island Lake, China.Acta Ecologica Sinica,2015,35(20):6759-6768.