曾 冀，雷淵才，賈宏炎，蔡道雄，唐繼新

(1.中國林業(yè)科學研究院熱帶林業(yè)實驗中心，廣西 憑祥 532600; 2. 中國林業(yè)科學研究院資源信息研究所，北京 100091)

桂西南馬尾松人工林生長對不同強度采伐的動態(tài)響應*

曾 冀1,2，雷淵才2**，賈宏炎1，蔡道雄1，唐繼新1

(1.中國林業(yè)科學研究院熱帶林業(yè)實驗中心，廣西 憑祥 532600; 2. 中國林業(yè)科學研究院資源信息研究所，北京 100091)

馬尾松；強度采伐；密度效應；生長動態(tài)

馬尾松(PinusmassonianaLamb.) 是我國南方亞熱帶地區(qū)分布最廣、資源最多的松類樹種，不僅具有很高的經(jīng)濟價值，而且在森林生態(tài)系統(tǒng)恢復和重建中發(fā)揮著重要作用[1]。桂西南地區(qū)熱量豐富、雨量充沛且雨熱同季，是馬尾松高產(chǎn)區(qū)之一；然而，由于大面積成片馬尾松純林經(jīng)營，出現(xiàn)蟲害頻發(fā)、生態(tài)功能下降等問題[2]。為解決馬尾松蟲害問題，中國林業(yè)科學研究院熱帶林業(yè)實驗中心(以下簡稱熱林中心) 自2005年以來，陸續(xù)開展了馬尾松人工林近自然化改造的探索,方法是選擇適宜的采伐強度，在林下套種鄉(xiāng)土闊葉樹進行馬尾松人工純林近自然化改造，促進其向馬尾松-闊葉異齡林的轉(zhuǎn)變，并加快馬尾松大徑材培育速度。本研究于2007年，對熱林中心14年生馬尾松人工林開始進行近自然化改造的不同強度采伐試驗，定期開展生長觀測，以期揭示不同強度采伐下馬尾松林分的生長動態(tài)，為完善馬尾松人工林近自然經(jīng)營提供參考。

早在19世紀，瑞士和斯洛文尼亞即開展近自然森林經(jīng)營研究，Schütz[3]研究了近自然化改造100年后的歐洲橡樹林，發(fā)現(xiàn)近自然森林經(jīng)營能很好地解決采伐和天然更新等經(jīng)營問題。Ward[4]對北美紅櫟(QuercusrubraL.) 及Miller[5]對北美紅櫟 、山櫟(QuercusprinusL.) 、美國黑櫻桃(PrunusserotinaEhrh.)和黃楊木(LiriodendrontulipiferaL.)的研究均表明，采伐能促進幼齡林的胸徑生長。Smith等[6]對北美紅櫟及Stringer等[7]對白櫟(QuercusfabriHance)的研究發(fā)現(xiàn)，強度采伐亦能促進成熟林的胸徑生長。Trimble[8]對黃楊木和美國黑櫻桃及Lamson等[9]對加拿大糖槭(AcernegundoLinn.)的一些研究認為,采伐會減緩樹高生長；Smith等[10]的研究則認為,采伐對美國黑櫻桃、加拿大糖槭的樹高生長基本無影響，但對黃楊木的樹高生長具促進作用。相對于常規(guī)間伐，近自然經(jīng)營中的采伐強度更大，主要針對林分中的目標樹進行單株管理，使目標樹在較短的時間內(nèi)達到目標胸徑[11]。從國內(nèi)有關近自然經(jīng)營采伐的研究報道可看出，大部分是關于采伐后的林下物種多樣性[12]、森林更新[13]和目標樹生長[14]等研究，而關于林木生長對采伐的動態(tài)響應研究較少，僅李婷婷等[15]研究了杉木人工林近自然化改造后的林分生長，比較了47%和61%兩個強度采伐后4年內(nèi)林分蓄積生長量和單木生長量等動態(tài)變化。盡管目前已有一些關于馬尾松、杉木間伐方面的研究[16-18]，而對不同強度采伐后的馬尾松生長動態(tài)鮮有報道。為此，本文利用馬尾松近自然改造試驗林，以系統(tǒng)研究馬尾松生長指標與采伐強度間的相關性，為馬尾松人工林近自然化改造工作提供依據(jù)和指導。

1 試驗地概況

1993年，在熱林中心伏波實驗場用種源為寧明桐棉的1年生裸根苗營造馬尾松人工純林，株行距為2.0 m×2.5 m，初植密度為2 000株·hm-2,于1999年和2003年分別進行了強度約20%的透光伐和強度約30%的撫育性間伐。

2 研究方法

2.1 試驗設計

表1 樣地概況

注：Ⅰ、Ⅱ、Ⅲ和Ⅳ表示處理，其采伐強度分別為80%、73%、66%和59%；下標為區(qū)組編號。

Notes: Ⅰ, Ⅱ, Ⅲ and Ⅳ refer to thinning treatments, and their intensities are 80%, 73%, 66% and 59%, respectively; and their subscripts are codes of blocks in the experiment.

2.2 生長觀測

采伐作業(yè)前，在馬尾松純林內(nèi)設置3塊400 m2的圓形樣地進行本底調(diào)查，調(diào)查樣地內(nèi)所有馬尾松植株的胸徑、樹高、枝下高和冠幅。應用圍尺進行每木檢尺，采用皮尺分東、西、南、北4個方向測定冠幅，VERTEX超聲波測高器測量樹高和枝下高。林分平均保留密度為1 100株·hm-2，平均胸徑18.26 cm，平均樹高11.64 m，平均蓄積量150.25 m3·hm-2。采伐后，在每個小區(qū)中心位置附近選取一個圓心點布設半徑為11.3 m、面積400 m2的圓形樣地，分別于2008、2010、2012、2014年底和2016年8月對所有保留木進行生長觀測。

2.3 數(shù)據(jù)處理

冠面積為東西、南北2個方向冠幅的乘積。

單株材積(V):V=g×f×h

式中：h為全樹高(m)；g為胸高斷面積(m2)；f為平均實驗形數(shù)，馬尾松取0.39[19]。

采用單因素方差分析和Duncan多重比較檢驗不同采伐強度下馬尾松林分的胸徑、樹高、單株材積和蓄積年均增長量及枝下高、冠面積年均變化量，應用SPSS16.0 軟件進行數(shù)據(jù)統(tǒng)計分析。由于套種的植株尚未進入主林層，對馬尾松生長的影響較小，故本研究在分析生長動態(tài)時未予考慮。

3 結果與分析

3.1 胸徑生長動態(tài)

表2 采伐后第1年和第9年馬尾松林分的生長表現(xiàn)

注：表中字母為Duncan多重比較結果，處理間具相同字母表示差異不顯著(P≥0.05), 不同字母表示差異顯著(P<0.05)。

Note: Values followed by the same letters in a column are not significantly different among treatments at 0.05 level according to Duncan’s multiple range tests.

圖1 不同采伐強度馬尾松人工林胸徑年均增長量(大寫字母表示同一采伐強度處理年際間差異；小寫字母表示同一年份采伐強度處理間的差異。具相同字母表示差異不顯著(P≥0.05)；不同字母表示差異顯著(P<0.05)，下同。)
Fig.1 Mean annual growth rate of diameter at breast height(DBH) in Pinus massoniana plantations after thinning with different intensities (Colum values with the same lowercase and capital letters are not significantly different among years after thinning with each intensity and among thinning treatments in each year according to Duncan’s multiple range tests at the 5% level. The same below.)

3.2 樹高生長動態(tài)

圖2 不同采伐強度馬尾松人工林樹高年均增長量
Fig. 2 Mean annual growth rate of height in Pinus massoniana plantations after thinning with different intensities

3.3 枝下高動態(tài)變化

圖3 不同采伐強度馬尾松人工林枝下高年均增長量
Fig.3 Mean annual increase of crown base height (CBH) in Pinus massoniana plantations after thinning with different intensities

3.4 冠面積動態(tài)變化

圖4 不同采伐強度馬尾松人工林冠面積年均增長量
Fig.4 Mean annual growth rate of crown area (CA) in Pinus massoniana plantations after thinning with different intensities

3.5 單株材積生長動態(tài)

圖5 不同采伐強度馬尾松人工林單株材積年均增長量
Fig.5 Mean annual growth rate of individual tree volume (ITV) in Pinus massoniana plantations after thinning with different intensities

3.6 馬尾松林分蓄積動態(tài)變化

圖6 不同采伐強度馬尾松人工林蓄積年均增長量
Fig.6 Mean annual growth rate of stand volume (SV) in Pinus massoniana plantations after thinning with different intensities

4 討論

林下套種闊葉樹對保留木生長存在一定的影響，但本研究未考慮其對上層林木的影響；然而，隨著時間的推移可能逐漸出現(xiàn)套種林木與馬尾松的水肥競爭。另一方面，闊葉樹的凋落物分解快，可以加速林地的養(yǎng)分循環(huán)，從而對林下物種多樣性、土壤等亦會產(chǎn)生積極影響。不同強度采伐后，林分的恢復是一個長期的過程，采伐強度越大，則影響的持續(xù)時間越長[31]?？偠灾狙芯恐皇遣煞ズ篑R尾松生長動態(tài)研究的階段性總結，未來闊葉樹逐漸進入主林層，馬尾松的生長動態(tài)必然會受影響；林下植被的變化亦會影響地力，進而影響林分生產(chǎn)力[32-34]，有待長期觀測研究。

5 結論

[1] 雷 蕾, 肖文發(fā), 曾立雄, 等. 不同營林措施對馬尾松林土壤呼吸影響[J]. 林業(yè)科學研究, 2015, 28(5): 713-719.

[2] 馬歸燕. 馬尾松天然林病蟲害調(diào)查[J]. 中國森林病蟲, 2001, 20(2): 40-41.

[3] Schütz J P. Close-to-nature silviculture: is this concept compatible with species diversity? [J]. Forestry, 1999, 72(4): 359-366.

[4] Ward J S. Crop-tree release increase growth of red oak saw timber: 12 year results[C]. Proceedings 16th Central Hardwood Forest Conference, 2008：457-465.

[5] Miller G W. Effect of crown growing space on the development of young hardwood crop trees[J]. Northern Journal of Applied Forestry, 2000, 17(1): 25-35.

[6] Smith H C, Miller G W. Releasing 75-to 80-year-old Appalachian hardwood saw timber trees: 5-year DBH response[C]. Proceedings of the 8th Central Hardwood Forest Conference, 1991：403-413.

[7] Stringer J W, Miller G W, Wittwer R F. Applying a crop-tree release in small-saw timber white oak stands[R]. Research Paper-Northeastern Forest Experiment Station, USDA Forest Service NE-620, 1988.

[8] Trimble G R. Response to crop tree release by 7-year-old stems of yellow-poplar and black cherry[R]. Research Paper-Northeastern Forest Experiment Station, USDA Forest Service NE-303, 1973.

[9] Lamson N I, Smith H C. Response to crop-tree release: sugar maple, red oak, black cherry, and yellow-poplar saplings in a 9-year-old stand[R]. Research Paper -Northeastern Forest Experiment Station, USDA Forest Service NE-394, 1978.

[10] Smith H C, Lamson N I. Precommercial crop-tree release increases diameter growth of Appalachian hardwood sapling[R]. Research Paper - Northeastern Forest Experiment Station, USDA Forest Service NE-534, 1983.

[11] 陸元昌. 近自然森林經(jīng)營理論與實踐[M]. 北京: 科學出版社，2006.

[12] 馬履一, 李春義, 王希群, 等. 不同強度間伐對北京山區(qū)油松生長及其林下植物多樣性的影響[J]. 林業(yè)科學, 2007, 43(5): 1-9.[13] 李 榮, 何景峰, 張文輝, 等. 近自然經(jīng)營間伐對遼東櫟林植物組成及林木更新的影響[J]. 西北農(nóng)林科技大學學報：自然科學版, 2011, 39(7): 83-91.

[14] 王懿祥, 張守攻, 陸元昌, 等. 干擾樹間伐對馬尾松人工林目標樹生長的初期效應[J]. 林業(yè)科學, 2014, 50(10): 67-73.

[15] 李婷婷, 陸元昌, 龐麗峰, 等. 杉木人工林近自然經(jīng)營的初步效果[J]. 林業(yè)科學, 2014, 50(5): 90-100.

[16] 盛煒彤. 不同密度杉木人工林林下植被發(fā)育與演替的定位研究[J]. 林業(yè)科學研究, 2001, 14(5): 463-471.

[17] Miller G W, Stringer J K. Effect of crown release on tree grade and DBH growth of white oak sawtimber in eastern Kentucky[C]. Proceedings of the 14th Central Hardwood Forest Conference, 2004: 27-44.

[18] 徐金良, 毛玉明, 鄭成忠, 等. 撫育間伐對杉木人工林生長及出材量的影響[J]. 林業(yè)科學研究, 2014, 27(1): 99-107.

[19] 孟憲宇. 測樹學(第二版) [M]. 北京：中國林業(yè)出版社，1996.

[20] Zhang J, Oliver W W, Powers R F. Long-term effects of thinning and fertilization on growth of red fir in northeastern California[J]. Canadian Journal of Forest Research, 2005, 35(6): 1285-1293.

[21] O’Hara K L, Nesmith J C B, Leonard L,etal. Restoration of old forest features in coast redwood forests using early-stage variable-density thinning[J]. Restoration Ecology, 2010, 18(s1): 125-135.[22] Condés S, Sterba H. Derivation of compatible crown width equations for some important tree species of Spain[J]. Forest Ecology & Management, 2005, 217(2): 203-218.

[23] Russell M B, Weiskittel A R. Maximum and largest crown width equations for 15 tree species in Maine[J]. Northern Journal of Applied Forestry, 2011, 28(2): 84-91.

[24] 公寧寧, 馬履一, 賈黎明, 等. 不同密度和立地條件對北京山區(qū)油松人工林樹冠的影響[J]. 東北林業(yè)大學學報, 2010, 38(5): 9-12.

[25] 符利勇, 孫 華. 基于混合效應模型的杉木單木冠幅預測模型[J]. 林業(yè)科學, 2013, 49(8): 65-74.

[26] Medhurst J L, Beadle C L, Neilsen W A. Early-age and later-age thinning affects growth, dominance, and intraspecific competition inEucalyptusnitensplantations[J]. Canadian Journal of Forest Research, 2001, 31(2): 187-197.

[27] 張水松, 陳長發(fā), 吳克選, 等. 杉木林間伐強度試驗20年生長效應的研究[J]. 林業(yè)科學, 2005, 41(5): 56-65.

[28] 諶紅輝, 方升佐, 丁貴杰, 等. 馬尾松間伐的密度效應[J]. 林業(yè)科學, 2010, 46(5): 84-91.

[29] 孟京輝, 陸元昌, 王懿祥, 等. 海南島熱帶天然次生林生長動態(tài)研究[J]. 林業(yè)科學研究, 2010, 23(1): 77-82.

[30] 蔡道雄, 賈宏炎, 盧立華, 等. 我國南亞熱帶珍優(yōu)鄉(xiāng)土闊葉樹種大徑材人工林的培育[J]. 林業(yè)科學研究, 2007, 20(2): 165-169.

[31] Misson L, Vincke C, Devillez F. Frequency responses of radial growth series after different thinning intensities in Norway spruce (Piceaabies(L.) Karst.) stands[J]. Forest Ecology and Management, 2003, 177(1-3): 51-63.

[32] 盛煒彤. 杉木林的密度管理與長期生產(chǎn)力研究[J]. 林業(yè)科學, 2001, 37(5): 2-9.

[33] 雷相東, 陸元昌, 張會儒, 等. 撫育間伐對落葉松云冷杉混交林的影響[J]. 林業(yè)科學, 2005, 41(4): 78-85.

[34] 熊有強, 盛煒彤. 不同間伐強度杉木林下植被發(fā)育及生物量研究[J]. 林業(yè)科學研究, 1995,8(4): 408-412.

(責任編輯：徐玉秀)

Dynamic Growth Response ofPinusMassonianaPlantation on Intensive Thinning in Southwestern Guangxi, China

ZENGJi1,2,LEIYuan-cai2,JIAHong-yan1,CAIDao-xiong1,TANGJi-xin1

(1. Tropical Forestry Research Center , Chinese Academy of Forestry, Pingxiang 532600, Guangxi，Chian; 2. Research Institute of Forest Resources Information Techniques, Chinese Academy of Forestry, Beijing 100091，Chian)

[Objective]Growth dynamics of Pinus massoniana were studied under intensive thinning so as to screen out suitable thinning intensity and provide technical support for close-to-nature management of Masson pine plantations. [Method] A thinning trial was conducted in a 14-year-old Masson pine plantation with stand density of 1 100 trees per hectare in October, 2007. Four thinning treatments including 225, 300, 375 and 450 trees left per hectare and the control without thinning were arranged. Since 2008, growth performance such as diameter at breast height (DBH), height, height of crown base and crown area were measured every two years, and wood volumes were calculated at the single tree and stand level. These data were analyzed through one-way variance analysis and Duncan multiple range tests to reveal dynamical responses of these index to all sorts of thinning intensities. [Result] Stand growth performance were significantly influenced by thinning intensity, mean annual increments of DBH, single tree volume, crown area decreases with increase of stand density of thinning treatments, but they were all significantly higher than those of the control (P<0.05). The crown area increments of Masson pine were the highest during year 1 to 3 after thinning, while increments of DBH were the highest during year 3 to 5. No obvious relationship was observed between tree height growth rate and thinning density. Increases of crown base height and stand volume were significantly affected by stand density, and they increased with increase of stand density, while the differences of stand volume decreased with increase of forest age. [Conclusion] In the present study, Masson pine’s response of crown growth to intensive thinning was the most sensitive and rapid. The crown area increased sharply at first, then resulted in rapid growth of DBH, while tree height and crown base height increased a bit stably. Thinning with four intensities all remarkably influenced the growth of single tree volume, but only thinning with 225 trees left per hectare had significant effect on increment of stand volume. Taking mean annual increments of the single tree volume and stand volume, thinning intensity with 300 trees left per hectare was recommended for close-to-nature management of 15-year-old Masson pine plantations in southwestern Guangxi.

Pinusmassoniana; intensive thinning; density effect; growth dynamics

2016-09-23 基金項目： 全國森林經(jīng)營基礎研究項目(169201531)及中國林業(yè)科學研究院熱帶林業(yè)實驗中心主任基金(RL-2012-02) 作者簡介： 曾 冀(1981—)，男，四川自貢人，在讀博士生，工程師，主要從事森林培育與經(jīng)營研究. * 致謝：承蒙中國林業(yè)科學研究院熱帶林業(yè)研究所曾杰研究員審閱修改論文，特致謝忱！ ** 通訊作者.

10.13275/j.cnki.lykxyj.2017.02.021

S791.248

A

1001-1498(2017)02-0335-07