南方红壤丘陵区微地形对芒萁生长特征及其土壤肥力的影响

Effects of microtopography on Dicranopteris dichotoma growth characteristics and soil fertility in an experiment plot in red soil hilly region of South China

关键词:  生态恢复, 植物-土壤系统, 微地形, 芒萁, 中国南方红壤丘陵区

Key words:  ecological restoration, plant-soil system, microtopography, Dicranopteris dichotoma, red soil hilly region of South China

摘要:

该研究以福建省长汀县来油坑野外实验区为研究区,分析了微地形如何影响芒萁生长特征和土壤养分。结果表明:(1)芒萁斑块中的微地形面积比例顺序为脊部<上坡<中坡<下坡<沟谷,其中脊部面积比例为9.38%,上坡、中坡和下坡分别为18.55%、19.63%和22.71%,沟谷为28.43%。(2)所有芒萁生长特征包括高度、密度、地上生物量、地下生物量和总生物量与部分土壤肥力因子包括有机质、全氮(TN)、碱解氮(AN)、速效钾(AK)和pH值在三种微地形(脊部、沟坡和沟谷)分别存在显著差异,并按自沟谷经沟坡到脊部的顺序分别趋于下降,而pH值反之。所有芒萁生长特征与部分土壤肥力因子(有机质、全氮、碱解氮、速效钾和pH值)分别呈显著正相关,基本上与部分土壤肥力因子(全磷、速效磷、全钾和< 2 μm 黏粒质量分数)分别无显著相关。(3)沟谷的地表温度和地下5 cm温度比脊部分别低3.51 ℃和1.65 ℃,而沟谷的地下5 cm湿度比脊部高约40%。(4)微地形对芒萁生长特征和土壤养分具有重要影响。在南方红壤丘陵区,应创建微地形尤其是沟谷以诱发芒萁群落演替,进而加速生态恢复进程。

Abstract:

Field work, laboratory experiment, geographic information system(GIS), and global positioning system(GPS)were used to explore how microtopography influenced the distribution of Dicranopteris dichotoma patches, growth characteristics, soil fertility factors and microenvironment factors in the experiment plot in Laiyoukeng of Changting County, Fujian Province, which is a typical representative of the red soil hilly region of China. The results were as follows:(1)The percentage of microtopographites increased in order ridge < upper slope < middle slope < lower slope < valley in D. dichotoma patches. The ridge occupied 9.38% of the total area; the upper slope, the middle slope, and the lower slope were almost evenly distributed(18.55%, 19.63% and 22.71%); the valley accounted for 28.43% of the total area in D. dichotoma patches.(2)There were significant differences in all D. dichotoma growth characteristics including plant height, plant density, aboveground biomass, underground biomass, and total biomass and part of soil fertility factors including organic matter, total nitrogen(TN), alkali-hydrolyzable nitrogen(AN), available kalium(AK), and pH value among the three microtopographies(ridge, slope, and valley), respectively, and they tended to decrease in order from the valleys through the slopes to the ridges, respectively, while pH value tended to increase in the same order. TP, available P, TK, and < 2 μm clay content were not significantly different among the three microtopographies, respectively. All D. dichotoma growth characteristics were significantly correlated positively with part of soil fertility factors(organic matter, TN, AN and AK), respectively, while all D. dichotoma growth characteristics were significantly correlated negatively with pH value, respectively. There was no significant correlation between all D. dichotoma growth characteristics and other soil fertility factors [TP, available phosphorus(AP), TK, and < 2 μm clay content](except for AP and plant density), respectively.(3)Surface temperature, temperature underground 5 cm, and moisture underground 5 cm showed statistically significant differences between the ridges and valleys, respectively(P < 0.05). Surface temperature and temperature underground 5 cm in the valleys were significantly lower than those of the ridges, respectively, while moisture underground 5 cm on the valleys was significantly higher than that of the ridges.(4)Microtopography plays an important role in D. dichotoma growth characteristics and soil fertility. Microtopography especially valley should be created to trigger the succession of D. dichotoma communities, so as to accelerate ecological restoration in the red soil hilly region of South China.