林窗大小對馬尾松人工林凋落葉可溶性有機碳損失的影響1)

李勛　劉洋　張健　楊萬勤　張艷　鄧長春　張明錦　劉華

(四川農業大學,成都，611130)

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林窗大小對馬尾松人工林凋落葉可溶性有機碳損失的影響1)

李勛劉洋張健楊萬勤張艷鄧長春張明錦劉華

(四川農業大學,成都，611130)

基于人工林近自然改造，調控低山丘陵區馬尾松低效林林分結構，探明馬尾松人工林不同面積林窗下，凋落葉可溶性有機碳(DOC)釋放規律。以長江上游低山丘陵區人為采伐形成的馬尾松人工林7種林窗(100、225、400、625、900、1 225、1 600 m2)為研究對象，研究不同面積林窗的馬尾松(Pinusmassoniana)、紅椿(Toonaciliata)、樟(Cinnamomumcamphora)、楨楠(Phoebezhennan)等凋落葉可溶性有機碳(DOC)的損失率。結果表明：(1)林窗面積對凋落葉DOC損失率有顯著影響。中小面積林窗(225～625 m2)內凋落物的DOC損失率高于其它面積林窗。(2)經過1 a的分解，4種凋落葉的DOC損失率為61.55%～90.06%，其中：DOC損失率紅椿最高，馬尾松最低。(3)凋落葉的DOC損失主要集中在分解前期(0～90 d)，此后凋落葉的DOC損失速率不斷降低，且不同凋落物之間DOC損失速率的差異不斷減小。因此，在馬尾松低效林改造過程中，可利用中小面積林窗這一顯著作用，引入鄉土闊葉樹種紅椿、樟、楨楠，加速馬尾松人工林的物質循環，維持林地肥力。

可溶性有機碳；林窗；馬尾松人工林；馬尾松凋落葉

We adjusted the structure of forest and explored the regularity of litter dissolved organic carbon (DOC) release in seven gap sizes of aPinusmassonianaplantation in a hilly area of the upper reaches of Yangtze River. The experiment was set up inPinusmassonianaplantation with seven different gap sizes (100, 225, 400, 625, 900, 1 225, and 1 600 m2) established by artificial thinning. The contents of DOC forPinusmassoniana(Pm),Toonaciliate(Tc),Cinnamomumcamphora(Cc) andPhoebezhennan(Pz) were evaluated in different sized forest gaps, with closed canopy as the control. Litterbags were collected from the gap center and the closed canopy in December of 2013, February, May, August and November of 2014. The forest gap size had significant effects on DOC loss rate small and medium sized gaps (225-900 m2) had greater effect on DOC loss rate forPm,Tc,Cc, andPzleaf litter. Over one-year decomposition, variation trend of DOC loss rate of descending order for four species wasTc(90.06%),Cc(85.17%),Pz(78.74%) andPm(61.55%). The DOC loss rate for four species mainly was concentrated in the early decomposition stages (first 90 days), and then was decreased quickly, and the difference of DOC loss rate (per 30 days) among four species diminished gradually. Therefore, when we reconstruct the low-function forest, we can take advantage of small and medium sized gaps, introduce native broad-leaf tree speciesTc,Cc,Pzto accelerate nutrient cycling, and maintain the soil fertility ofPinusmassonianaplantation.

凋落物分解過程中可溶性有機碳(DOC)的釋放不僅是森林生態系統養分循環的重要環節,也對碳循環起著極其重要的作用[1-2]。DOC是森林生態系統中一類重要的、十分活躍的化學組分，也是微生物生長和生物分解過程中的重要能量來源。DOC對森林生態系統營養物質的有效性和流動性、污染物質的毒性及其遷移特性、pH有直接影響[3-4]。……