模拟增雨对荒漠灌木白刺枝叶生长的促进作用

根据年均降水量,分别在乌兰布和沙漠东北缘(内蒙古磴口,年均降水145 mm)和巴丹吉林沙漠东南缘(甘肃民勤,年均降水115 mm)对天然白刺灌丛进行不同梯度的增雨实验(年均降水量的0％、25％、50％、75％、100％).结果表明:增雨的比例越大,白刺形态特征的变化越明显;100％增雨对磴口和民勤白刺形态特征的影响最明显,能够显著增加白刺标记枝的长度、直径和干质量,但是对成熟叶片和新叶片数的影响不显著;增雨还显著增加了9月磴口和民勤白刺枝叶的干质量和鲜质量;在较干旱的民勤地区,较大的增雨量才能促进白刺枝条生长;50％增雨即可促进夏末磴口白刺枝条生物量增加,75％增雨才能促进夏末民勤白刺枝条生物量增加.

The Role of Increased Precipitation in Promoting Branch and Leaf Growth of Nitraria tangutorum

A rain-increasing test with different ratios of precipitation (0%, 25%, 50%, 75%, 100%) were conducted on natural Nitraria tangutorum shrubland based on the mean annual precipitations at the northeast margin of Ulan Buh Desert (Dengkou of Inner Mongolia, 145 mm) and southeast margin of Badan Jaran Desert (Minqin of Gansu Province, 115 mm). The results showed that the more the precipitation increased, the more the change of morphological traits of N.tangutorum. The effect of 100% precipitation-increasing on morphological traits of N.tangutorum was significant both at Dengkou and Minqin: including length, diameter and dry biomass of marked branch, but not including the amount of mature leaf or new leaf. Fresh biomass and dry biomass of branch and leaf of N.tangutorum were also enhanced by increased precipitation in September both at Dengkou and Minqin. More increased precipitation could promote branch growth of N.tangutorum in more arid area. The biomass of N.tangutorum was enhanced by 50% increased precipitation in late summer in Dengkou. However, it was enhanced by 75% increased precipitation in late summer in Minqin.