中文摘要：

2007年,对腾格里沙漠东南缘沙坡头地区1956年（51龄）和1981年（26龄）人工植被区及自然植被区的藻结皮净光合速率（Pn）变化,及其与结皮含水量（〉100%、40%～60%和〈20%）、大气CO2浓度（360和700 mg.L-1）和温度（13℃、24℃和28℃）的关系进行研究.结果表明：51龄、26龄人工植被区和自然植被区的藻结皮Pn分别为3.4、4.4和3.2μmol.m-2.s-1,且51龄人工植被区藻结皮的Pn显著高于26龄人工植被区和自然植被区;藻结皮含水量对其Pn影响显著,且中等含水量（40%～60%）藻结皮的Pn显著高于低含水量（〈20%）和高含水量（〉100%）;CO2倍增（700 mg.L-1）后,中等和高含水量藻结皮的Pn增加了1.8～3.3倍,而低含水量时,藻结皮的Pn变化不明显;高含水量和中等含水量处理时,24℃和28℃条件下藻结皮的Pn较13℃时提高27%～66%,而在低含水量时,不同温度的藻结皮Pn值无显著差异.

英文摘要：

Taking the 26-and 51-year-old artificial vegetation areas and the natural vegetation area in Shapotou region of southeast Tengger Desert as study sites,this paper measured the net photosynthetic rate（Pn） of algal crusts,and analyzed its relationships with crust water content（100%,40%-60%,and 20%）,atmospheric CO2 concentration（360 and 700 mg·L-1）,and air temperature（13 ℃,24 ℃,and 28 ℃）.The Pn of the crusts in the 26-and 51-year-old artificial vegetation areas and natural vegetation area was 3.4,4.4,and 3.2 μmol·m-2·s-1,respectively,and the Pn in 51-year-old artificial vegetation area was significantly higher than that in the other two areas.Crust water content had significant effects on the Pn,which was significantly higher at medium water content（40%-60%） than at low（20%） and high（100%） water content.When the CO2 concentration doubled（700 mg·L-1）,the Pn increased by 1.8-3.3 times at medium and high crust water content but had less change at low crust water content,compared with that under ambient CO2 concentration（360 mg·L-1）.At medium and high crust water content,the Pn at 24 ℃ and 28 ℃ was 27%-66% higher than that at 13 ℃（P0.05）,but at low crust water content,no significant difference was observed at the three temperatures.