川西高原中国沙棘叶和小枝养分物质对海拔升高的响应

Response of nutrient content in the leaves and branchlets of Hippophae rhamnoides L. to altitude in western Sichuan Plateau

以川西高原不同分布区域的中国沙棘为研究对象,分别沿米亚罗2 450～3 080 m和川主寺2 870～3 550 m海拔范围,测定不同海拔下叶和小枝氮(N)、磷(P)与非结构性碳水化合物(NSC)含量.结果表明:(1)在两个区域随着海拔升高,中国沙棘叶和小枝N、P、可溶性总糖(TSS)、淀粉、NSC等养分物质含量均呈非线性变化;(2)米亚罗区域叶N随着海拔升高的变化与叶NSC变化趋势一致,二者呈显著正相关关系,而在川主寺区域二者无显著相关性;(3)川主寺区域叶和小枝NSC含量整体上高于米亚罗区域,特别是小枝TSS含量较高,有利于其应对低温和干旱的环境,也可能是不利环境下碳投资受限导致;(4)在川主寺3 000 m以上的高海拔区域,叶N和光合碳水化合物供应充足,但光合产物的转运及转化为结构性物质可能受到了低温限制,全球气候变暖可能有利于中国沙棘生长和分布扩大。

The contents of nitrogen(N),phosphorus(P)and non-structural carbohydrates(NSC)in the leaves and branches of Hippophae rhamnoides L.were measured.These H.rhamnoides were planted along Miyaluo and Chuanzhusi,with altitudes ranging between 2 450-3 080 m and 2 870-3 550 m,respectively.The results showed that contents of N,P,total soluble sugar(TSS),starch and total NSC in leaves and branchlets varied nonlinearly with elevation in both regions.Changes in leaf N content along elevation was consistent with changes in leaf NSC conten in Miyaluo,while no significant correlation was detected for H.rhamnoides from Chuanzhusi.NSC content was generally higher in H.rhamnoides from Chuanzhusi than that from Miyaluo,especially with higher TSS content in branchlets.This was beneficial to cope with low temperature and drought environment,which also might be attributed to carbon investment constraint under unfavorable condition.For H.rhamnoides planted in elevation above 3 000 m in Chuanzhusi,soil N supply,photosynthesis and carbohydrate in leaves were adequate,though the transport and transformation of photosynthetic products to structural material could be restricted by low temperature,thus global warming is likely to help the expand and distribution of H.rhamnoides.