不同沙丘生境主要植物比叶面积和叶干物质含量的比较

研究了生长在不同沙丘生境中 (流动沙丘 ,半固定沙丘和固定沙丘 ) 2 0个植物种 (10个 1年生植物种和 10个多年生植物种 )的比叶面积 (SL A)和叶干物质含量 (L DMC)的变化 ,并且分析了各个沙丘生境的土壤养分特征。结果表明 ,各个植物种的平均 SL A和 L DMC在植物种之间差异显著 ;多数在两种或 3种沙丘生境均有分布的植物其 SL A在不同沙丘生境之间差异显著 ,但是仅有 6个植物种的 L DMC在不同沙丘生境之间表现出差异 (p<0 .0 5 )。与许多研究结果类似 ,1年生植物的 SL A显著大于多年生植物的 SL A,而且两者之间 L DMC存在一定的差异。 1年生植物 SL A和 L DMC之间相关性不显著 ,但多年生植物SL A和 L DMC之间呈显著负相关。综合所有 2 0个植物种可以发现 ,SL A增大时 ,L DMC有下降的趋势

Specific leaf area and leaf dry matter content of some plants in different dune habitats

Specific leaf area (SLA, leaf area per unit dry mass) and Leaf dry matter content (LDMC, the ratio of leaf dry mass to fresh mass) are important variables in plant ecology because they are associated with many critical aspects of plant growth and survival. In this paper, we examined variations in specific leaf area and leaf dry matter content of 20 dune plants (ten annuals and ten perennials) which have different distributional patterns in Kerqin sandy land, northern China. Our purposes were to detect the variations of SLA and LDMC in different dunes and different functional type. The selected species mainly distributed in three types of sandy land habitats: mobile sand dune, semi-fixed sand dune and fixed sand dune. We selected 15 individuals for each species in each type of dune. Three leaves on each individual were selected to study their SLA and LDMC according the procedure of Garnier et al. Soil characteristics of each habitat were analyzed to reveal the differences in three types of dunes. The results showed that the mean organic C, total N, total soluble salt remarkably decreased along fixed sand dune, semi-fixed sand dune and mobile sand dune. This decrease tendency was also found in values of organic C, EC and C: N. But the record value of soil PH did not vary with any of the other soil characteristics. The mean SLA and LDMC in different habitat varied significantly between species. The maximum SLA value (295 cm~2/g) was in the annual grass Setaria viridis on mobile sand dune, and the lowest SLA (86 cm~2/g) was recorded in the perennial grass Pennisetum centrasiatum on semi-fixed sand dune. LDMC was between 0.1 (for the annual forb Chenopodium glaucum on fixed sand dune) and 0.44 g/g (for the perennial grass Phragmitis australis on fixed sand dune). For the species distributed in three habitats or in two habitats, its SLA and LDMC were compared to detect the difference between habitats. The statistical results showed that the SLA of most species with wide distribution was significantly different between habitats (p-value<0.05) except for three species, Chenopodium glaucum, Euphorbia humifusa and Salix gordejevii. In the case of LMDC, six species showed no significant difference between habitats. Results of ANOVAS showed that there was a significant difference between perennial plants and annual plants for SLA (F=7.40, p-value <0.05) and LDMC (F=15.4, p-value <0.001). The mean SLA value for all measured perennial plants was 135.1 cm~2/g, which was lower than that for annual plants (192.7 cm~2/g). In the case of LDMC, the mean values for perennial plants and annual plants were 0.32 and 0.20 g/g, respectively. Although the detected correlation was not significant between SLA and LDMC for annuals, our results showed that increasing SLA was associated with decreased dry matter content.