半干旱沙地生境变化对植物地上生物量及其碳、氮储量的影响

研究了科尔沁沙地沙丘固定过程中的流动沙丘、半固定沙丘和固定沙丘以及草地4种生境类型的植物地上生物量及其碳、氮含量与储量特征。结果表明,沙地生境变化对植物叶干重、枝干重、总生物量及其碳、氮含量与储量均有显著影响(P<0.01);固定沙丘的叶干重、枝干重、总生物量及其碳氮储量均大于流动沙丘与半固定沙丘,草地的叶干重、枝干重、总生物量、枝和总的碳储量、枝的氮储量均小于固定沙丘而大于流动沙丘;半固定沙丘叶、枝及总碳含量与枝的碳储量大于流动沙丘,而叶、枝及总氮含量小于流动沙丘。一年生植物分别占流动沙丘、固定沙丘和草地总生物量的63.99%,79.28%,70.86%;灌木占半固定沙丘总生物量的73.15%;C₃植物生物量分别占流动、半固定、固定沙丘和草地总生物量的39.99%,90.87%,96.01%和82.67%。固定沙丘上的一年生植物和C₃植物的生物量、碳氮储量在4个生境中最高;半固定、固定沙丘和草地中C₃植物碳含量及其储量、氮储量均高于C₄植物。沙丘固定过程中生物量及其碳氮储量逐渐增加,固定沙丘植被具有较大的碳氮固存潜力,一年生植物、C₃植物对其碳氮的固存具有重要的贡献作用;沙丘固定过程中C₃植物对C₄植物生物量的下降具补偿作用。

Effect of change in semiarid sand dune habitat on aboveground plant biomass,carbon and nitrogen

This study examined the characteristics of aboveground plant biomass, carbon (C) content, nitrogen (N) content and total C and N of four different habitats; mobile, semi-stable and stable dunes (three stages of sand dune stabilization) and natural grassland at Horqin, Inner Mongolia, in Northern China. The change in sand dune habitat had significant impacts on leaf dry weight, branch dry weight, total biomass, C and N contents and total C and N. Leaf and branch dry weight, total biomass, % C and N and total C and N in the fixed dune were higher than those in mobile and semi-stable dunes. Total biomass, leaf and branch dry weight, total branch C, total biomass C and total branch N in the grassland were lower than those in the stable dune, but higher than those in the mobile dune. The leaf and branch C %, total C % and total branch C in the semi-stable dune were higher than those in the mobile dune, while leaf and branch N % and total N in the semi-stable dune were lower than the mobile dune. Annual plant species separately accounted for 63.99%, 79.28%, 70.86% of the total biomass in the mobile dune, stable dune and grassland respectively, while shrubs accounted for 73.15% of the total biomass in the semi-stable dune. C₃ plant species contributed 39.99%, 90.87%, 96.01%, 82.67% of the total biomass in the mobile, semi-stable and stable dunes and grassland respectively. The biomass, total C and N of annuals and C₃ plants in the stable dune were higher than in the other habitats. In semi-stable and stable dunes and grassland, the C %, total C and N of C₃ plants were higher than those of C₄ plants. The results indicate that total biomass, C and N increase gradually during sand dune stabilization. Plants on the stable dune had greater potential to sequester C and N, mostly contributed by annuals and C₃ species. The C₃ species also provided an important buffer against the decrease in C₄ plant biomass during the sand dune stabilization process.