Interspecific associations and niches of dominant bryophytes under different planted forests in the North Shanxi province

Background  The sandy-hilly region in North China has been affected by long-term water and wind erosion, resulting in serious desertification, thus it is urgent to restore the local vegetation. Bryophytes are the pioneer plants in the spontaneous succession and have strong soil-fixing ability, and they play an important role in soil conservation and combating desertification. Therefore, selecting the dominant bryophytes suitable for ecological restoration may promote the succession process of revegetation. Youyu county in the northern Shanxi province, an area suffered from heavily desertification, is a typical national-level demonstration area in China for combating desertification after over 70 years of revegetation efforts since early 1950s.

Methods  In September 2020, a total of 12 planted forests and 2 controls (a bare land and spontaneous grassland, respectively) with bryophyte growth were selected as sampling plots at Songtao Garden in Youyu county of Shanxi province. Bryophyte boxes were used for sampling, and related environmental factors were recorded, and the bryophyte species were identified by LEICA fluorescence microscope DM2500 and Nikon Stereo microscope SMZ745T. And then the interspecific associations and niches of 14 dominant bryophytes under different planted forests with different re-vegetated years on a sandy-hilly region in the North Shanxi were quantitatively analyzed by the methods of χ² test, Spearman rank correlation coefficient, niche width and overlap index.

Results  1) The life-form of 85.71% dominant bryophytes under different planted forests on a sandy-hilly region in the northern Shanxi belonged to the short turf with drought-barren resistance, and the species composition of dominant bryophytes was closely related to the type of planted forest. 2) Among 91 species-pairs composed of 14 dominant bryophytes, the positive and negative correlation ratios of χ² test and Spearman rank correlation coefficient were all < 1, and there were no significant association among most species-pairs. 3) The 14 dominant bryophytes were divided into 3 ecological species groups, and the major environmental factors leading to the differentiation of ecological species groups were soil moisture and light conditions. 4) The values of ecological overlap of most dominant bryophyte species-pairs were generally low, and the degrees of their interspecific associations were linearly correlated with the values of ecological niche overlap. 5) The dominant species of Bryum caespiticium had the largest niche and widely distributed in the bryophyte community.

Conclusions  The dominant bryophytes under different planted forests on a sandy-hilly region in the North Shanxi had low degree of interdependence, loose interspecific associations, and distributed independently. The dominant species of B. caespiticium could be used as a best pioneer bryophyte species for planting in future ecological restoration.