不同植茶年限土壤碳氮養(yǎng)分及胞外酶對(duì)干旱脅迫的響應(yīng)

趙 杏,鐘一銘,楊京平,呂亞敏,王小鵬

浙江大學(xué)環(huán)境與資源學(xué)院環(huán)境保護(hù)研究所,杭州 310058

不同植茶年限土壤碳氮養(yǎng)分及胞外酶對(duì)干旱脅迫的響應(yīng)

趙 杏,鐘一銘,楊京平*,呂亞敏,王小鵬

浙江大學(xué)環(huán)境與資源學(xué)院環(huán)境保護(hù)研究所,杭州 310058

全球氣候變暖導(dǎo)致的夏季干旱事件頻發(fā)影響茶園生態(tài)系統(tǒng)生產(chǎn)力,而茶葉是我國(guó)南方主要的經(jīng)濟(jì)作物,因此研究干旱條件下不同植茶年限茶園土壤養(yǎng)分、生態(tài)酶活性及微生物生態(tài)變化具有重要意義。選取杭州市余杭區(qū)徑山茶園3種不同植茶年限(10a、30a和50a)土壤和鄰近的荒土為研究對(duì)象,研究不同水分(干旱組30% WFPS(water-filled pore space)和對(duì)照組55% WFPS)處理前、第7天和第14天的土壤碳氮養(yǎng)分(可溶性有機(jī)碳DOC,總有機(jī)碳TOC,微生物碳MBC,微生物氮MBN,銨態(tài)氮NH4-N,硝態(tài)氮NO3-N)和胞外酶活性(涉碳胞外酶：β-葡萄糖苷酶BG,涉氮胞外酶：N-乙酰氨基葡萄糖苷酶+亮氨酸氨基肽酶NAG+LAP)變化,探討不同水分對(duì)不同植茶年限土壤生態(tài)系統(tǒng)的影響。結(jié)果表明,茶園土壤碳庫(kù)及涉碳、涉氮胞外酶活性隨著植茶年限增加先升高后降低(30a最高)；土壤氮庫(kù)養(yǎng)分隨著植茶年限增加而增加。干旱處理增加了土壤TOC、NH4-N、NO3-N含量,而降低了土壤MBC含量、BG和NAG+LAP活性。處理前后植茶年限30a土壤DOC、MBN、NO3-N和涉碳、涉氮胞外酶含量最高,且其干旱組土壤DOC、TOC、MBC、MBN含量與對(duì)照組比變幅相對(duì)較小,可推斷植茶年限30a左右的土壤微生態(tài)環(huán)境豐富,對(duì)外界環(huán)境變化的抵抗力較強(qiáng)。

茶園土壤；植茶年限；土壤養(yǎng)分；胞外酶活性；干旱

土壤是茶葉生長(zhǎng)的載體,土壤質(zhì)量對(duì)茶葉的產(chǎn)量和質(zhì)量有直接作用,茶園施用大量化學(xué)氮肥在增加茶葉產(chǎn)量的同時(shí),也加劇了土壤的酸化,使得土壤pH隨植茶年限的增長(zhǎng)逐漸降低[1-2],土壤養(yǎng)分利用受到限制[3]。為了分析土壤環(huán)境質(zhì)量,越來(lái)越多的研究通過(guò)土壤的養(yǎng)分和土壤酶的活性整合分析來(lái)評(píng)價(jià)土壤質(zhì)量[4-5]。土壤碳氮含量是土壤質(zhì)量的重要指標(biāo),對(duì)土壤生產(chǎn)力和可持續(xù)利用以及環(huán)境保護(hù)有重要意義[6],土壤胞外酶和土壤微生物量在土壤有機(jī)殘?bào)w分解和養(yǎng)分循環(huán)中有著重要作用[7], 是有效的評(píng)價(jià)土壤微生物分解能力、土壤肥力和土壤生態(tài)穩(wěn)定性的指標(biāo)[8-9]。此外,不同耕作年限對(duì)土壤養(yǎng)分有不同影響,岷江地區(qū)人工生態(tài)林的研究發(fā)現(xiàn)土壤有機(jī)碳和氮儲(chǔ)量隨著林齡的增長(zhǎng)總體呈增加趨勢(shì)[10]。也有研究表明,不同植茶年限的土壤理化性狀有所不同[11],導(dǎo)致土壤碳氮養(yǎng)分和胞外酶活性有所差異,荒地種植茶樹后,土壤微生物量碳和酶活性顯著增加,隨著植茶年限的增長(zhǎng)表現(xiàn)出先增加后減少的趨勢(shì)[12]。因此,茶園土壤的質(zhì)量管理和土壤種植年限已成為茶園生態(tài)系統(tǒng)主要的研究焦點(diǎn)。

氣候變化研究表明,過(guò)去30年中夏季極端氣候出現(xiàn)的頻率增加,夏季的平均溫度逐年升高[13],而茶樹是我國(guó)重要的經(jīng)濟(jì)作物之一,南方夏季持續(xù)高溫和干旱將會(huì)導(dǎo)致茶葉產(chǎn)量低且品質(zhì)差[14]。有研究表明,干旱降低土壤物質(zhì)的流動(dòng)性,從而減少微生物可用資源[15]；干旱通過(guò)限制底物擴(kuò)散和誘導(dǎo)微生物生理壓力[15]對(duì)土壤微生物生物量和微生物多樣性產(chǎn)生負(fù)面影響[16]。也有研究表明在全球變暖背景下,干旱過(guò)程中土壤凈硝化速率在一定程度上受到抑制,土壤硝態(tài)氮含量降低[17]；土壤中微生物活性和酶活性降低,土壤碳循環(huán)受阻[18],影響土壤中作物所需氮源和碳源養(yǎng)分供應(yīng)。

綜上所述,不同植茶年限土壤具有不同的生態(tài)環(huán)境,可能導(dǎo)致其對(duì)干旱事件的響應(yīng)不同,然而不同植茶年限土壤碳氮養(yǎng)分和胞外酶活性以及其對(duì)干旱脅迫的響應(yīng)尚不明確,因此,本研究比較不同植茶年限(10、30a和50a)的茶園和荒地土壤在不同水分(干旱組30% WFPS和對(duì)照組55% WFPS)處理前后土壤碳氮養(yǎng)分以及胞外酶活性變化,明確土壤質(zhì)量指標(biāo)隨時(shí)間以及干旱脅迫的變化,促進(jìn)對(duì)不同植茶年限土壤質(zhì)量的綜合評(píng)價(jià)。本試驗(yàn)研究數(shù)據(jù)結(jié)果將為促進(jìn)全球氣候變化條件下茶園產(chǎn)業(yè)的發(fā)展,保障茶園土壤生態(tài)系統(tǒng)健康,提高茶葉產(chǎn)量和質(zhì)量提供理論依據(jù)。

1 材料與方法

1.1 試驗(yàn)地點(diǎn)和供試材料

供試土壤采自浙江大學(xué)余杭徑山茶學(xué)基地,該基地位于杭州市余杭徑山鎮(zhèn), 30°23′N,119°53′E。選擇施肥情況相似,成土母質(zhì)(第四紀(jì)紅壤)相同的10—12a(Y10)、28—30a(Y30)和48—50a(Y50)植茶年限的茶園作為研究對(duì)象,同時(shí)選取茶園附近的荒地(CK)作為對(duì)照。于2013年5月從各茶園小區(qū)(每個(gè)類型3個(gè))隨機(jī)S形取5個(gè)位點(diǎn)表層0—10 cm土壤,除去石礫、碎屑以及植物根系,相同土壤樣品混勻后過(guò)2mm篩。取部分保存用于生理生化指標(biāo)測(cè)定；剩余土壤樣品用于后續(xù)模擬試驗(yàn)。土壤本底性狀指標(biāo)見表1。

表1 土壤性質(zhì)

1.2 試驗(yàn)處理

實(shí)驗(yàn)通過(guò)室內(nèi)土壤培養(yǎng),采用48個(gè)(2種含水量×2次取樣時(shí)間×4種土壤樣品×3次重復(fù))7.5cm(直徑)×10cm(高)的PVC管,底部包上紗布防止土壤掉落；每個(gè)PVC管中裝入300 g新鮮土壤置于恒溫培養(yǎng)箱,設(shè)置兩水平土壤含水量30%(干旱組)和55% WFPS(對(duì)照組),25℃恒溫培養(yǎng)兩周,每天用注射器注射無(wú)菌純水調(diào)節(jié)土壤水分,第7天和第14天破壞性取樣。采集的土壤樣品分兩份,一份4℃保存,一份風(fēng)干,用于相關(guān)指標(biāo)檢測(cè)分析。

1.3 測(cè)定方法

土壤pH采用雷磁pH復(fù)合電極測(cè)量水浸提(土∶水=1∶2.5)后的溶液；土壤總有機(jī)碳(TOC)、水溶性有機(jī)碳(DOC)采用Multi N/C 2100總有機(jī)碳分析儀測(cè)定；土壤氨氮(NH4-N)和硝氮(NO3-N)用2 mol/L KCl溶液浸提(土∶液=1∶5)后,分別用靛酚藍(lán)比色法和紫外雙波長(zhǎng)比色法測(cè)定。土壤微生物碳氮(MBC和MBN)采用氯仿熏蒸進(jìn)而用提取劑提取分別測(cè)定[19-20]。β-葡萄糖苷酶(BG)、N-乙酰氨基葡萄糖苷酶(NAG)和亮氨酸氨基肽酶(LAP)活性采用微平板熒光比色法測(cè)定,基質(zhì)均購(gòu)自sigma公司。采用多功能酶標(biāo)儀(MD5,Molecular Devices)檢測(cè)熒光,365 nm激發(fā),460 nm檢測(cè)熒光強(qiáng)度。每個(gè)樣品重復(fù)8次,酶活性計(jì)算參照DeForest[21]。

1.4 數(shù)據(jù)處理與分析

實(shí)驗(yàn)數(shù)據(jù)通過(guò)Excel 2007計(jì)算,Origin 8.5制圖。在SPSS 16.0中采用重復(fù)測(cè)量方差分析檢驗(yàn)土壤水分、植茶年限和取樣時(shí)間對(duì)土壤化學(xué)性狀和胞外酶活性的影響。采用LSD檢驗(yàn)比較每個(gè)時(shí)間點(diǎn)不同處理間差異；采用Pearson相關(guān)性分析檢驗(yàn)土壤各指標(biāo)之間的相關(guān)性。

2 結(jié)果與分析

2.1 水分處理前后不同植茶年限土壤碳庫(kù)特征

茶園土壤中可溶解性有機(jī)碳(DOC)含量顯著大于荒地土壤,干旱處理顯著增高土壤DOC含量(P<0.05)。各土壤類型DOC含量順序?yàn)?Y10≥Y30>Y50>Y0,Y10、Y30和Y50土壤DOC較Y0分別高86.93%、95.78%和58.96%(圖1)。土壤總有機(jī)碳(TOC)含量隨植茶年限增加而升高,處理前Y10、Y30和Y50土壤TOC分別是Y0土壤的2.29倍、2.72倍和6.23倍。干旱處理TOC含量顯著高于對(duì)照處理(P<0.05)(圖1)。

處理前Y10、Y30和Y50土壤微生物碳(MBC)較Y0分別高106.67%、85.39%和44.62%。處理7d后,干旱組MBC含量顯著高于對(duì)照組。14d后各植茶年限土壤MBC含量為Y30>Y10>Y50>Y0(圖2)。處理前土壤β-葡萄糖苷酶(BG)活性隨植茶年限增加先升高后下降,Y10、Y30和Y50土壤BG活性分別是Y0土壤的2.92、4.19和1.25倍。處理后,Y10和Y30土壤BG活性大幅度降低,干旱組活性顯著低于對(duì)照組(圖2)。

2.2 水分處理前后不同植茶年限土壤氮庫(kù)特征

處理前土壤硝態(tài)氮(NO3-N)含量和土壤銨態(tài)氮(NH4-N)含量隨植茶年限增加而升高,NO3-N含量范圍為3.72—43.41 g/kg,NH4-N含量范圍為34.21—80.27 g/kg。7d和14d后土壤NO3-N含量升高,干旱組NO3-N含量顯著高于對(duì)照組；土壤NH4-N含量呈升高趨勢(shì),干旱組顯著高于對(duì)照組(圖3)。

水分處理之前土壤微生物氮(MBN)隨著植茶年限的增加而顯著增加,Y30到Y(jié)50增幅最大約為63%。處理7d和14d后,土壤MBN含量顯著降低(圖4)。而水分處理之前土壤涉氮酶活性(NAG+LAP)隨著植茶年限增加先升高后降低,Y30最高為21.79 mmol g-1h-1,但是Y50降低至和Y10水平16—17 mmol g-1h-1。水分處理后,各植茶年限土壤 NAG+LAP活性趨勢(shì)不變,土壤NAG+LAP活性干旱組低于對(duì)照組(圖4B)。

圖1 各植茶年限土壤不同水分處理下可溶性有機(jī)碳和總有機(jī)碳變化Fig.1 Variations of DOC and TOC with different tea cultivation ages incubation at 30% and 55%WFPS30%和55%代表含水量30%和55%WFPS; 不同小寫和大寫字母分別代表同一時(shí)間30%和55%WFPS處理不同植茶年限土壤養(yǎng)分差異性顯著,*代表同一時(shí)間相同茶齡不同水分處理間土壤養(yǎng)分差異性顯著(P<0.05); 圖中數(shù)據(jù)均為平均值±標(biāo)準(zhǔn)差(n=3)

圖2 各植茶年限土壤不同水分處理下微生物碳和β-葡糖糖苷酶活性變化Fig.2 Variations of MBC and activities of BG with different tea cultivation ages incubation at 30% and 55%WFPS

圖3 各植茶年限土壤不同水分處理下銨態(tài)氮和硝態(tài)氮變化Fig.3 Variations of soil ammonia and nitrate nitrogen with different tea cultivation ages incubation at 30%WFPS and 55%WFPS

圖4 各植茶年限土壤不同水分處理下微生物氮和N-乙酰氨基肽酶+亮氨酸氨基肽酶活性Fig.4 Soil MBN content and activities of NAG+LAP with different tea cultivation ages incubation at 30% and 55%WFPS

2.3 土壤碳-氮庫(kù)特征之間的關(guān)系

土壤涉碳、氮生化性質(zhì)指標(biāo)之間相關(guān)性特征如表2所示。除BG外,所有涉碳和氮指標(biāo)均和pH呈極顯著(P<0.01)負(fù)相關(guān),這說(shuō)明茶園土壤中pH值是土壤養(yǎng)分的限制因素。土壤NO3-N和NH4-N、TOC、MBC、DOC呈極顯著(P<0.01)正相關(guān),和BG呈顯著(P<0.05)負(fù)相關(guān)。NH4-N和MBN呈極顯著(P<0.01)負(fù)相關(guān),和TOC、DOC呈極顯著(P<0.01)正相關(guān)。MBN和NAG+LAP、TOC、BG之間極顯著(P<0.01)正相關(guān),NAG+LAP和BG、DOC和TOC、MBC、BG呈極顯著(P<0.01)正相關(guān)。這說(shuō)明干旱對(duì)涉碳酶和涉氮酶活性的抑制作用一致,進(jìn)而影響土壤碳氮養(yǎng)分含量；同時(shí)土壤碳庫(kù)和氮庫(kù)的養(yǎng)分之間相互影響,一方的變化會(huì)直接影響另一方的特征。

表2 土壤涉碳氮生化性質(zhì)之間的相關(guān)性分析

* 表示顯著相關(guān)(P<0.05), **表示極顯著相關(guān)(P<0.01); NO3-N：硝態(tài)氮 nitrate nitrogen; NH4-N：銨態(tài)氮 ammonia nitrogen; MBN：微生物氮 microbial biomass nitrogen; NAG+LAP：N-乙酰氨基肽酶和亮氨酸基肽酶活性 N-acetylglucosaminidase and l-leucine aminopetidase activity; TOC：總有機(jī)碳 Total organic carbon; MBC：微生物碳 microbial biomass carbon; BG：β-葡萄糖苷酶β-1,4-glucosidase activity; DOC：可溶解性有機(jī)碳 dissolved organic matter

3 討論

本研究表明水分處理前土壤NH4-N、NO3-N、MBN以及TOC隨植茶年限增長(zhǎng)而升高,說(shuō)明研究區(qū)植茶及茶園生產(chǎn)管理使土壤碳庫(kù)、氮庫(kù)養(yǎng)分積累。已有的研究報(bào)道表明果園土壤養(yǎng)分也表現(xiàn)出相似規(guī)律[22],最主要的原因是人為長(zhǎng)期輸入化肥造成土壤養(yǎng)分積累。而茶園土壤MBC和DOC隨植茶年限增長(zhǎng)而降低,這可能是由于植茶年限長(zhǎng)的土壤酸化嚴(yán)重,土壤微生物活性降低從而降低有機(jī)礦化能力[12,23]。BG和NAG+LAP活性隨植茶年限增長(zhǎng)先升高后降低,有研究表明脲酶、蔗糖酶[24]、脲酶和磷酸酶[2]活性也隨著人為耕作時(shí)間的增長(zhǎng)呈現(xiàn)先增加后降低的趨勢(shì),這可能是由于植茶年限50a的土壤微生物量低、pH低等原因?qū)е碌?pH通過(guò)控制微生物的酶產(chǎn)物、離子化引起的酶構(gòu)象變化以及基質(zhì)的實(shí)用性來(lái)影響土壤酶活性[25]?？梢娺m當(dāng)年限的植茶耕作可以豐富土壤中養(yǎng)分含量以及茶園生態(tài)環(huán)境中的生化過(guò)程。

本研究進(jìn)一步表明不同植茶年限土壤對(duì)干旱的響應(yīng)也是不一致的。土壤水分、植茶年限、水分處理時(shí)間以及三者的交互作用直接影響到茶園土壤碳庫(kù)和氮庫(kù)養(yǎng)分含量以及涉碳、涉氮胞外酶活性。經(jīng)過(guò)不同的水分處理,干旱組的土壤TOC、DOC、NH4-N和NO3-N含量比對(duì)照組高,這可能是由于干旱降低了土壤微生物的活性從而降低了微生物對(duì)土壤無(wú)機(jī)養(yǎng)分的利用程度[26],進(jìn)一步影響土壤中碳和氮的氧化分解的釋放態(tài)勢(shì)[26],也可能在干旱條件下一些細(xì)菌合成了碳水化合物[27]。對(duì)照組NO3-N含量低于干旱組的一部分原因可能是濕潤(rùn)環(huán)境下土壤中反硝化作用更完全從而向空氣中釋放更多的N2[28]。Wang等[29]和Schindlbacher等[30]的研究結(jié)果表明土壤NO3-N濃度升高伴隨著NH4-N濃度的降低,這與本研究的結(jié)果不一致,這可能是由于干旱條件下土壤礦化還在進(jìn)行,但是會(huì)降低氨氧化古菌和氨氧化細(xì)菌豐度來(lái)抑制銨態(tài)氮向硝態(tài)氮轉(zhuǎn)化導(dǎo)致的[29]。水分處理后,Y50土壤中NO3-N含量大于Y0卻小于Y10和Y30含量,這可能是由于Y50土壤強(qiáng)酸性抑制了土壤硝化細(xì)菌活性[31]。水分處理后土壤中MBC含量顯著減少,且MBN含量與NH4-N含量具有顯著的負(fù)相關(guān)性,由此可以推測(cè)出土壤培養(yǎng)實(shí)驗(yàn)MBN可能被礦化轉(zhuǎn)化成NH4-N；荒地土壤MBC含量變化不大,而茶園土壤MBC含量升高,植茶年限10a和30a的土壤含量增幅最大,這表明植茶年限短的土壤保持更高的活性,相似的研究結(jié)果表明種植年限久的果園微生態(tài)環(huán)境更貧乏[22]。干旱處理的土壤BG和NAG+LAP活性比對(duì)照組低,Zsolt等[32]研究也表明水分高的土壤BG和磷酸酶的活性更高；Y30土壤胞外酶處理前后活性表現(xiàn)更高,研究表明磷酸酶的活性和土壤溫度、水分、pH有關(guān)[33],因此可推斷不同植茶年限不同的土壤由于具有不同的pH,所以其酶活性對(duì)不同水分的響應(yīng)也不同,Y30土壤為本研究范圍內(nèi)酶活性最適條件。土壤碳庫(kù)和氮庫(kù)養(yǎng)分具有顯著相關(guān)性,干旱處理通過(guò)降低BG和NAG+LAP活性(加速植物源殘?jiān)姆纸?提高微生物源DOC和活性氮的產(chǎn)生[34])和微生物的分解利用,進(jìn)而影響土壤中碳庫(kù)和氮庫(kù)的轉(zhuǎn)化。研究結(jié)果表明干旱對(duì)微生物分解利用養(yǎng)分的抑制作用大于對(duì)活性養(yǎng)分生成的抑制作用,而植茶年限為30a的土壤不僅具有相對(duì)高的養(yǎng)分含量,并且在干旱脅迫條件下微生態(tài)環(huán)境表現(xiàn)出更強(qiáng)的耐受力,可見在一定年限內(nèi)茶園耕作有利用土壤養(yǎng)分積累以及土壤生態(tài)環(huán)境的多樣性建立,但是當(dāng)耕作年限過(guò)長(zhǎng),土壤質(zhì)量降低,酸化成為土壤養(yǎng)分生化過(guò)程的限制因素,土壤質(zhì)量降低,從而影響其對(duì)外界脅迫的抵抗力。

4 結(jié)論

茶園土壤養(yǎng)分比荒地養(yǎng)分含量高,隨著植茶年限的增長(zhǎng),碳庫(kù)養(yǎng)分含量及涉碳涉氮胞外酶活性呈現(xiàn)先升高后降低的趨勢(shì),植茶年限30a土壤養(yǎng)分含量和酶活性達(dá)到最高；氮庫(kù)養(yǎng)分隨著植茶年限的增長(zhǎng)呈現(xiàn)遞增趨勢(shì)。干旱對(duì)土壤碳、氮庫(kù)養(yǎng)分和涉碳、涉氮胞外酶活性有顯著性影響,干旱增加土壤有機(jī)碳、銨態(tài)氮、硝態(tài)氮含量,降低土壤微生物量含量、土壤胞外酶活性。處理前后植茶年限30a土壤可溶性有機(jī)碳、微生物氮、硝氮和涉碳涉氮胞外酶含量最高,且其干旱組土壤的可溶性有機(jī)碳、總有機(jī)碳微生物碳氮的含量與對(duì)照組相比變幅相對(duì)較小,可推斷植茶年限30a左右的土壤微生態(tài)環(huán)境豐富,抵抗力強(qiáng)。因此,隨著茶園植茶年限的增長(zhǎng),需要考慮茶園土壤的生物生化環(huán)境,采取合理的施肥和綠色覆蓋等措施來(lái)提高茶園土壤環(huán)境。

[1] Han W Y, Kemmitt S J, Brookes P C. Soil microbial biomass and activity in Chinese tea gardens of varying stand age and productivity. Soil Biology and Biochemistry, 2007, 39(7): 1468-1478.

[2] Xue D, Yao H Y, Huang C Y. Microbial biomass, N mineralization and nitrification, enzyme activities, and microbial community diversity in tea orchard soils. Plant and Soil, 2006, 288(1/2): 319-331.

[3] 李瑋, 鄭子成, 李廷軒. 不同植茶年限土壤團(tuán)聚體碳氮磷生態(tài)化學(xué)計(jì)量學(xué)特征. 應(yīng)用生態(tài)學(xué)報(bào), 2015, 26(1): 9-16.

[4] Badiane N N Y, Chotte J L, Pate E, Masse D, Rouland C. Use of soil enzyme activities to monitor soil quality in natural and improved fallows in semi-arid tropical regions. Applied Soil Ecology, 2001, 18(3): 229-238.

[5] Gil-Sotres F, Trasar-Cepeda C, Leirós M C, Seoane S. Different approaches to evaluating soil quality using biochemical properties. Soil Biology and Biochemistry, 2005, 37(5): 877-887.

[6] Shaffer M J, Ma L W, Hansen S. Modeling Carbon and Nitrogen Dynamics for Soil Management. Florida: CRC Press, 2001: 672-672.

[7] Enowashu E, Poll C, Lamersdorf N, Kandeler E. Microbial biomass and enzyme activities under reduced nitrogen deposition in a spruce forest soil. Applied Soil Ecology, 2009, 43(1): 11-21.

[8] Ajwa H A, Dell C J, Rice C W. Changes in enzyme activities and microbial biomass of tallgrass prairie soil as related to burning and nitrogen fertilization. Soil Biology and Biochemistry, 1999, 31(5): 769-777.

[9] Caldwell B A. Enzyme activities as a component of soil biodiversity: A review. Pedobiologia, 2005, 49(6): 637-644.

[10] 羅達(dá), 馮秋紅, 史作民, 李東勝, 楊昌旭, 劉千里, 何建社. 岷江干旱河谷區(qū)岷江柏人工林碳氮儲(chǔ)量隨林齡的動(dòng)態(tài). 應(yīng)用生態(tài)學(xué)報(bào), 2015, 26(4): 1099-1105.

[11] 薛冬. 茶園土壤微生物群落多樣性及硝化作用研究[D]. 杭州: 浙江大學(xué), 2007.

[12] Yao H, He Z, Wilson M J, Campbell C D. Microbial biomass and community structure in a sequence of soils with increasing fertility and changing land use. Microbial Ecology, 2000, 40(3): 223-237.

[13] Hansen J, Sato M, Ruedy R. Perception of climate change. Proceeding of the National Academy Sciences of the United States of America, 2012, 109(37): E2415-E2423.

[14] 付曉青, 陳佩, 秦志敏, 肖潤(rùn)林, 楊知建. 遮蔭處理對(duì)丘陵茶園生態(tài)環(huán)境及茶樹氣體交換的影響. 中國(guó)農(nóng)學(xué)通報(bào), 2011, 27(8): 40-46.

[15] Schimel J, Balser T C, Wallenstein M. Microbial stress-response physiology and its implications for ecosystem function. Ecology, 2007, 88(6): 1386-1394.

[16] Hueso S, Garcia C, Hernandez T. Severe drought conditions modify the microbial community structure, size and activity in amended and unamended soils. Soil Biology and Biochemistry, 2012, 50: 167-173.

[17] 徐冰鑫, 陳永樂, 胡宜剛, 張志山, 李剛, 李夢(mèng)茹, 陳棟. 干旱過(guò)程中荒漠生物土壤結(jié)皮-土壤系統(tǒng)的硝化作用對(duì)溫度和濕度的響應(yīng)——以沙坡頭地區(qū)為例. 應(yīng)用生態(tài)學(xué)報(bào), 2015, 26(4): 1113-1120.

[18] Allison S D, Treseder K K. Warming and drying suppress microbial activity and carbon cycling in boreal forest soils. Global Change Biology, 2008, 14(12): 2898-2909.

[19] Ross D J. Influence of sieve mesh size on estimates of microbial carbon and nitrogen by fumigation-extraction procedures in soils under pasture. Soil Biology and Biochemistry, 1992, 24(4): 343-350.

[20] Vance E D, Brookes P C, Jenkinson D S. An extraction method for measuring soil microbial biomass C. Soil Biology and Biochemistry, 1987, 19(6): 703-707.

[21] DeForest J L. The influence of time, storage temperature, and substrate age on potential soil enzyme activity in acidic forest soils using MUB-linked substrates and L-DOPA. Soil Biology and Biochemistry, 2009, 41(6): 1180-1186.

[22] Qian X, Gu J, Sun W, Li Y D, Fu Q X, Wang X J, Gao H. Changes in the soil nutrient levels, enzyme activities, microbial community function, and structure during apple orchard maturation. Applied Soil Ecology, 2014, 77: 18-25.

[23] Wardle D A. A comparative-assessment of factors which influence microbial biomass carbon and nitrogen levels in soil. Biological Reviews of the Cambridge Philosophical Society, 1992, 67(3): 321-358.

[24] 董燕, 董坤, 鄭毅, 田芝花, 魯耀, 湯利. 種植年限和種植模式對(duì)設(shè)施土壤微生物區(qū)系和酶活性的影響. 農(nóng)業(yè)環(huán)境科學(xué)學(xué)報(bào), 2009, 28(3): 527-532

[25] Tabatabai M A. Soil enzymes // Weaver R W, Angle S, Bottomley P, Bezdicek D, Smith S, Tabatabai A, Wollum A, eds. Methods of Soil Analysis. Part 2. Microbiological and Biochemical Properties. Madison: Soil Science Society of America, 1994: 775-833.

[26] Muhr J, Franke J, Borken W. Drying-rewetting events reduce C and N losses from a Norway spruce forest floor. Soil Biology and Biochemistry, 2010, 42(8): 1303-1312.

[27] Kohler J, Caravaca F, Roldán A. Effect of drought on the stability of rhizosphere soil aggregates ofLactucasativagrown in a degraded soil inoculated with PGPR and AM fungi. Applied Soil Ecology, 2009, 42(2): 160-165.

[28] Davidson E A, Swank W T, Perry T O. Distinguishing between nitrification and denitrification as sources of gaseous nitrogen-production in soil. Applied and Environmental Microbiology, 1986, 52(6): 1280-1286.

[29] Wang H, Yang J P, Yang S H, Yang Z C, Lv Y M. Effect of a 10 degrees C-elevated temperature under different water contents on the microbial community in a tea orchard soil. European Journal of Soil Biology, 2014, 62: 113-120.

[30] Schindlbacher A, Zechmeister-Boltenstern S, Butterbach-Bahl K. Effects of soil moisture and temperature on NO, NO2, and N2O emissions from European forest soils. Journal of Geophysical Research Atmospheres, 2004, 109(D17): D17302.

[31] Wang H, Xu R K, Wang N, Li X H. Soil Acidification of Alfisols as Influenced by Tea Cultivation in Eastern China. Pedosphere, 2010, 20(6): 799-806.

[32] Kotroczó Z, Veres Z, Fekete I, Krakomperger Z, Tóth J A, Lajtha K, Tóthmeresz B. Soil enzyme activity in response to long-term organic matter manipulation. Soil Biology and Biochemistry, 2014, 70: 237-243.

[33] Kang H J, Freeman C. Phosphatase and arylsulphatase activities in wetland soils: annual variation and controlling factors. Soil Biology and Biochemistry, 1999, 31(3): 449-454.

[34] Lipson D A, Schmidt S K. Seasonal changes in an alpine soil bacterial community in the colorado rocky mountains. Applied and Environmental Microbiology, 2004, 70(5): 2867-2879.

The response of soil nutrients (carbon and nitrogen) and extracellular enzyme activities to drought in various cultivation ages from tea orchards

ZHAO Xing, ZHONG Yiming, YANG Jingping*, Lü Yamin,WANG Xiaopeng

InstituteofEnvironmentalProtection,CollegeofEnvironmentalandResourceScience,ZhejiangUniversity,Hangzhou310058,China

Frequent summer droughts, caused by climate change, have negatively affected the productivity and quality of tea orchard soil. Tea (CamelliasinensisL.) is an important cash crop in southern China, therefore it is important to examine soil nutrients, enzyme activity, and microbial community structural shifts under such summer drought conditions in various cultivation ages. In this study, the pot method was utilized to investigate the soil quality of various cultivation ages of 0, 10, 30, and 50 years. These pots were incubated at 25oC and given two different water treatments (30% and 55% WFPS (water-filled pore space)). Throughout the incubation period, soil samples were taken to measure the soil carbon, nitrogen content, and extracellular enzyme activities at 0, 7, and 14 days. The results indicated that prior to the incubation period, nitrate nitrogen, ammonia nitrogen, microbial nitrogen, and the total organic carbon in the soil increased with cultivation age. The microbial carbon and the extracellular enzyme activities (β-1,4-glucosidase activity related to soil carbon and N-acetylglucosaminidase and l-leucine aminopetidase activity related to soil nitrogen) were highest at the cultivation age of 30. Soil samples taken under drought conditions, displayed increased extracellular enzyme activities, soil organic carbon, soil nitrate nitrogen, and ammonia nitrogen contents while soil microbial carbon and extracellular enzyme activities declined. The soil samples taken from a cultivation age of 30 exhibited a relatively high amount of dissolved organic carbon, microbial nitrogen, nitrate nitrogen, and soil extracellular enzyme activities throughout all incubation periods. The drought conditions had a significant influence on the contents of soil nitrate nitrogen, ammonia nitrogen, total organic carbon, and microbial carbon. Furthermore, the correlation analysis of soil carbon and nitrogen related biochemical properties indicated that the carbon and nitrogen soil nutrients affected one another. The results of the study indicated that a 30-year cultivation of the tea tree had a positive effect on the accumulation of soil nutrients but tea tree cultivation for almost 50 years produced an inferior micro-ecological environment. Thus, to improve the soil environment in tea orchards, measures such as balancing fertilization and green cover, should be considered.

tea orchards; cultivation age; soil nutrients; extracellular enzyme; drought

高等學(xué)校博士學(xué)科點(diǎn)專項(xiàng)科研基金資助項(xiàng)目(20130101110127)；水體污染控制與治理科技重大專項(xiàng)資助項(xiàng)目(2014ZX07101-012)

2015-08-09;

日期:2016-06-13

10.5846/stxb201508091678

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

趙杏,鐘一銘,楊京平,呂亞敏,王小鵬.不同植茶年限土壤碳氮養(yǎng)分及胞外酶對(duì)干旱脅迫的響應(yīng).生態(tài)學(xué)報(bào),2017,37(2):387-394.

Zhao X, Zhong Y M, Yang J P, Lü Y M,Wang X P.The response of soil nutrients (carbon and nitrogen) and extracellular enzyme activities to drought in various cultivation ages from tea orchards.Acta Ecologica Sinica,2017,37(2):387-394.