固定沙丘结皮层藓类植物多样性及固沙作用研究

STUDY ON DIVERSITY AND BINDING-SAND EFFECT OF MOSS ON BIOTIC CRUSTS OF FIXED DUNES

根据对沙坡头固定沙丘生物结皮的物种调查、鉴定及盖度和生物量的研究,藓类植物共2科,7属,16种,以真藓(Bryum argentuum)为优势种。随着固沙时间的延长,生物结皮中藓类和藻类总盖度呈上升趋势;沿不同年代固定沙丘坡面向上等距离梯度,藓类盖度显著下降,而藻类盖度则平稳上升。对不同年代固定沙丘生物结皮优势种真藓的生物量和固沙量的测定表明,随沙丘固定年代的增加,真藓的生物量和固沙量增加,50年代固沙区结皮层真藓生物量是944.33 kg·hm^(-2),固沙量是3.925×10~4kg·hm^(-2),但固沙率随时间的增加而减少。真藓的饱和吸水量与生物量呈正相关,50年代固定沙丘藓类结皮层可吸水7.06×10~3kg·hm^(-2),说明藓类结皮层具有很强的吸水和保水能力,对于干燥少雨的沙漠地区具有十分重要的生态学意义。

The study area, Shapotou district (37°27' N, 104°57' E) of Ningxia Hui Autonomous Region is situated in the southeastern fringe of the Tengger Desert of China. A study of species identification, coverage and biomass in the soil microbiotic crusts of fixed sand dunes was conducted in Shapotou district, from which we found two families, seven genera and sixteen species of mosses. Didymodon constrictus (Mitt. ) Saito and D. tectorwn ( C. Muell. ) Saito were reduced to synonymy of D. vinealis ( Brid.) Zand. by Zander and Red-fearn. Crossidium chloronotos (Brid. ) Limpr. , Crossidium aberrans Holz. & Bartr. Aloina obliquifolia ( C. Muell. ) Broth. and Tortilla atrovirens ( Sm. ) lindb. are new to Shapotou district. Bryum argenteum is an eu-rytopic species that survives on all kinds of habitat, and is the dominant component that forms moss synusia. The community of Didymodon vinealis, D. rigidulus Hedw. var. ditrichoides and Syntrichia bidentata are found on hillocks and are randomly distributed in crusts. Diversity of species is the highest in this area in the natural fixed dunes, with sixteen species, followed by five species of mosses (31.3%) in the fixed dunes of 1956, four species of mosses (25.0%) in the fixed dunes of 1964, and only two species of mosses (12.5%) in the fixed dunes of 1981. The total coverage of mosses and algae increased with the fixed-sand time, hi different ages, the coverage of mosses and algae exist in an equal distance gradient, while in the fixed dunes they exist along the slope with the coverage of mosses decreasing as that of algae increased. A determination of biomass and binding-sand quantity of the dominant species-Bryum argenteum showed that its biomass (944.03 kg·hm-2) and binding-sand (3.925 × 104 kg·hm-2) quantity increased when the fixed sand time prolonged in moss crusts of the fixed dunes of 1950s. While the rate of binding-sand of Bryum argenteum decreased, its saturated water absorption had a positive correlation with biomass of 7.06 ×103 kg·hm-2 . Therefore the results indicate that the moss crusts had a strong ability to absorb and reserve water, which is of ecological significance in arid desert region.