内蒙古典型草原小叶锦鸡儿灌丛地上净初级生产力和种群结构对火烧的响应

摘要/Abstract

摘要： 针对全球范围内由于长期过度放牧引起的草原群落灌丛化问题,本研究以内蒙古锡林河流域小叶锦鸡儿灌丛化的羊草草原为研究对象,通过连续2年的人为控制火烧实验,从株丛和群落2个组织水平研究了火烧对小叶锦鸡儿的影响。结果表明,1)在内蒙古锡林河流域的退化恢复草原群落中,小叶锦鸡儿种群属于增长型的种群,中、小株丛所占的比例较大。实验区内所调查的6588个株丛中,冠幅为0～50cm的株丛占30%,50～150cm的株丛占49%,>150cm的株丛仅占21%;2)在群落水平上,一年火烧和连续2年火烧对小叶锦鸡儿株丛的生长均具有显著的抑制作用,其地上净初级生产力比火烧前分别减少了27%和66%;3)火烧显著地增加了小叶锦鸡儿的枝条密度和茎的生物量分配,减少了叶的生物量分配,使茎叶比由1∶4.4升高为1∶1.1;4)同50～150和>150cm2个冠幅组的大株丛相比,火烧对0～50cm小灌丛影响最为明显,一年火烧和连续2年火烧使其地上净生物量分别下降了57%和60%。实验结果表明,火烧显著地削弱了小叶锦鸡儿的生活力,有效地抑制了其小株丛的生长,对控制灌丛的进一步扩张具有明显的作用。

Abstract: The density and cover of the native shrub species Caragana microphylla, has greatly increased in recent decades in the Xilin River basin of Inner Mongolia, in areas previously dominated by Leymus chinensis and Stipa grandis. We conducted a field experiment of one- and two-years burning in a typical successional steppe dominated by C. microphylla. Our main objective was to determine whether and how the prescribed burning can be used as a management tool for controlling shrub encroachment of the Inner Mongolia grasslands. The effects of prescribed burning on morphological traits, aboveground biomass, and biomass allocation of C. microphylla were examined. Pretreatment measurements were made in 2005 and the first prescribed burning was in 2006 with the second repeat burning in 2007. Results showed that: 1) C. microphylla may have been an expanding population in our experimental plots. Of the 6,588 individual shrubs examined, 30% were small-crown size shrubs (0-50 cm), 49% were mid-crown size shrubs (50-150 cm), and only 21% were large crown size shrubs (>150 cm); 2) At the plant community level, growth of C. microphylla was significantly inhibited by prescribed burning. The aboveground net primary productivity (ANPP) of C. microphylla was reduced by 27% for 1-year burning and by 66% for the 2-year repeat burning, compared with the initial ANPP before treatment; 3) Burning significantly enhanced the current year stem density of C. microphylla, increased biomass allocation to new stems, reduced biomass allocation to leaves, and shifted stem/leaf ratios from 1∶4.4 to 1∶1.1; 4) At the individual bunch level, the impact of burning on aboveground biomass production of C. microphylla varied with crown size. The largest reduction in aboveground biomass was found in the small-crown size class, in which the average aboveground biomass decreased by 57% for the 1-year burning and by 60% for the 2-year repeat burning. Results from this study suggest that prescribed burning is an effective approach for controlling the growth and encroachment of C. microphylla into the Inner Mongolia grasslands.

中图分类号:

S812

林燕,白永飞. 内蒙古典型草原小叶锦鸡儿灌丛地上净初级生产力和种群结构对火烧的响应[J]. 草业学报, 2010, 19(5): 170-178.

LIN Yan, BAI Yong-fei. Responses of aboveground net primary production and population structure of Caragana microphylla to prescribed burning in a typical steppe of Inner Mongolia[J]. Acta Prataculturae Sinica, 2010, 19(5): 170-178.

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