沙漠化过程中沙地植物群落生物量、热值和能量动态研究

Study on the Dynamics of Biomass, Calorific Value and Energy of the Psamophyte Communities during Desertification

对科尔沁沙地处于不同沙漠化阶段生境(丘间低地、固定沙丘、半固定沙丘、半流动沙丘和流动沙丘)的植物群落地上和地下(0～40 cm)生物量、热值以及能量现存量进行了初步研究.结果表明:①从丘间低地到流动沙丘,地上生物量、地下生物量、地上与地下生物总量随沙漠化的进展分别下降90.1%,90.4%和90.3%;②地上和地下生物量各组分热值均表现为流动沙丘最低, 各生境内地上部组分平均热值高于地下部;地上活植物体热值随沙漠化进展呈现下降趋势, 但其余组分热值不随生境改变而呈现规律性变化;③地上与地下能量现存总量大小为丘间低地(16 193 kJ*m-2)>固定沙丘(11 720 kJ*m-2)>半固定沙丘(7 980 kJ*m-2)>半流动沙丘(3 453 kJ*m-2)>流动沙丘(1 512 kJ*m-2);从丘间低地到流动沙丘5个不同类型生境, 地上能量现存总量与地下能量现存总量的比值分别为0.57,0.59,1.09,0.80和0.58.

The study area （42°55′N, 120°42′E, 345 m a. s. 1. ） is located in the central-southern part of the Horqin Sandland in Naiman Banner, Tongliao City, Inner Mongolia Autonomous Region. It belongs to the continental semi-arid climate in the region, the annual temperature and the accumulated temperature ≥10℃ are 6.4 ℃ and 3 000～3 400 ℃ respectively; the annual precipitation is 364.6 mm, precipitation occurs mainly during the period from June to August, and the annual evaporation is 1 972.8 mm; the annual average wind speed is 3.5 m/s, and the days of occurring strong winds varies in a range of 20～60 days. In the region the landforms include the gentle-sloped mobile dunes, semi-mobile dunes, semi-fixed dunes, fixed dunes and interdune lowlands. The soil is dominated by aeolian sandy soil with porous soil texture, low organic matter content and poor water and fertilizer conservation, and the vegetation is dominated by psamophytes. In this paper, the aboveground and belowground （0～ 40 cm in depth） biomasses, calorific values and energies in biomass components in five different sandy habitats （interdune lowlands, fixed dunes, semi-fixed dunes, semimobile dunes, and mobile dunes） in the Horqin Sandland are measured and researched. The results are as follows： ① The aboveground biomass, belowground biomass, and total aboveground and belowground biomass are decreased by 90.1%, 90.4% , and 90.3% respectively with the development of desertification, i.e. , from the interdune lowlands to the mobile dunes; ② The calorific values are the lowest in all the aboveground and belowground biomass components of mobile dunes, and the average calorific value in aboveground components is higher than that in belowground ones. The calorific values in aboveground live vegetation are decreased with development of desertification, i.e. , from 18. 140 kJ·g^-1 at interdune lowland to 16. 633 kJ·g^-1 at a mobile dune, but they are not regularly changed with the change of inhabits in other components in aboveground or belowground part;③ The total aboveground and belowground energies are in a sequence of decreased interdune lowlands （16 193 kJ·m^-2） 〉 fixed dunes （11 720 kJ·m^-2） 〉 semi-fixed dunes （7 980 kJ·m^-2） 〉 semi-mobile dunes （3 453 kJ·m^-2） 〉 mobile dunes （1 512 kJ·m^-2）. The ratios between the aboveground energies and belowground energies at the interdune lowlands, fixed dunes, semi-fixed dunes, semi-mobile dunes and mobile dunes are 0.57, 0.59, 1.09, 0.80 and 0.58 respectively