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季节性雪被可能对高山森林凋落物分解产生重要影响,但一直没有深入的研究。该文采用凋落物分解袋法,于2010–2012年雪被覆盖下几个关键时期(冻结初期、深冻期和融化期)以及生长季节,研究了川西高山森林代表性树种岷江冷杉(Abies faxoniana)、红桦(Betula albosinensis)、四川红杉(Larix mastersiana)和方枝柏(Sabina saltuaria)凋落叶在不同厚度冬季雪被下的分解动态。经过两年的分解,不同雪被覆盖下岷江冷杉凋落物分解率为33.98%–39.55%,红桦为46.49%–48.22%,四川红杉为42.30%–44.93%,方枝柏为40.34%–43.84%。相对于无雪被覆盖环境,厚型雪被覆盖均小幅提高了4种凋落物两年的失重率(1.57%–5.57%)。3个针叶树种(岷江冷杉、四川红杉和方枝柏)Olson凋落物分解系数k均以厚型雪被覆盖最大,薄型雪被覆盖最小,而阔叶树种红桦分解系数k则表现为无雪被>薄型雪被>较厚型雪被>厚型雪被>中型雪被。尽管在第二年生长季中雪被对红桦凋落物分解的促进作用不明显,但雪被覆盖明显促进了两年各个关键时期岷江冷杉、四川红杉和方枝柏凋落物的分解。第一年雪被期凋落物分解对当年分解总量的贡献达42.5%–65.5%,季节性雪被变化明显改变了凋落物冬季分解格局,对深冻期凋落物分解过程影响尤为显著。综上所述,当前气候变化情景下冬季雪被的减少可能减缓该区森林凋落物分解过程,但相对于易分解的阔叶凋落物,针叶凋落物的响应特征可能更为强烈。
Seasonal snow may have a significant impact on the decomposition of alpine forest litter, but there has been no in-depth study. In this paper, we use litter decomposition bag method to study the effects of Abies faxoniana (Abies faxoniana), a representative tree species in the Alpine Forest in western Sichuan Province, during several key periods covered by snow from 2010 to 2012 (early freezing, deep freezing and thawing periods) ), Betula albosinensis, Larix mastersiana and Sabina saltuaria in different thicknesses of winter snow cover. After two years’ decomposition, the litter decomposition rate of Abies faxoniana was 33.98% -39.55% under different snow cover, 46.49% -48.22% of red birch, 42.30% -44.93% of Sichuan sequoia, 40.34% 43.84%. Relative to the snow-covered environment, thick snow cover slightly increased the weight loss rate of two litters (1.57% -5.57%) for two years. The decomposition coefficients of Olson litter in the three coniferous species (Minjiang River fir, Siberian redwood and S. chinensis) were all covered by the thick snow and the thin snow covered the least, while that of the broad-leaved tree Birch showed as no snow It is> thin snow> thick snow> thick snow> medium snow. Although the promotion effect of snow on the decomposition of Betula albosinensis was not obvious in the second growing season, the coverage of snow obviously promoted the decomposition of litter of Minjiang Fir, Sequoia chinensis and Radix Bupleurum in two key years. The contribution of snow litter decomposition in the first year to the total amount of decomposition in the current year was 42.5% -65.5%. Seasonal snow changes obviously changed winter litter decomposition pattern, especially for litter decomposition in deep freeze period. In conclusion, the reduction of snow cover in winter under current climate change scenarios may slow down litter decomposition in the area. However, the response characteristics of coniferous litter may be more intense than that of readily degraded broad-leaved litter.