呼伦贝尔沙地樟子松林净初级生产力对气候变化的响应

以呼伦贝尔沙地樟子松人工林为研究对象,利用树木年轮学和解析木法,推算过去41年樟子松林的生物量和年净初级生产力,并分析年净初级生产力与气温、降水、湿度等气象因子的关系。研究表明：随着林龄的增加,樟子松林生物量变化符合逻辑斯蒂生长方程;樟子松林生物量从1977年的4.83 t/hm²到2017年的167.95 t/hm²。樟子松林净初级生产力年际差异较大,呈先增加后减小、最后趋于稳定的趋势,多年平均净初级生产力为4.08 t hm^-2 a^-1,最高达到6.13 t hm^-2 a^-1,最低为2.63 t hm^-2 a^-1。气候因子与樟子松林净初级生产力关系较为密切,并具有一定的"滞后效应";樟子松林净初级生产力与上一年8月、12月和当年3月的降水量显著相关;净初级生产力与上一年和当年8-9月的月均湿度极显著正相关;净初级生产力与各月温度均呈不同程度的负相关,尤其是上一年和当年的6-9月温度显著影响着净初级生产力。研究表明,樟子松林净初级生产力受温度和降水的综合影响,净初级生产力与气候因子的关系属于温度敏感型,未来该地区持续升温的条件下樟子松林净初级生产力可能会降低。

Response of net primary productivity of Pinus sylvestris var. mongolica plantation to climate change in Hulunbuir sandy land

Pinus sylvestris var. mongolica is one of the main native plantation species in Hulunbuir sandy land. The response of net productivity of Pinus sylvestris var. mongolica plantation to changes of climatic factors is important to understand the relation between Pinus sylvestris var. mongolica plantation growth and climate change. Three plots were established with a size of 30 m×30 m in 43-years old Pinus sylvestris var. mongolica plantation in Hulunbuir sandy land. Combining the dendrochronological method and empirical biomass growth equations, the biomass and net primary productivity of Pinus sylvestris var. mongolica plantation in the past 41 years were calculated. And the correlations between net primary productivity and climatic factors were analyzed, including monthly air temperature, humidity and precipitation. The results indicated that the variation of biomass followed the logistic equation as the increasing forest age, and the biomass of the plantation increased from 4.83 t/hm² in 1977 to 167.95 t/hm² in 2017. The net primary productivity showed an inter-annual variation with a trend of increasing first, then decreasing, and finally stabilizing. The net primary productivity of the stand ranged between 2.63 t hm^-2 a^-1 and 6.13 t hm^-2 a^-1 with an average of 4.08 t hm^-2 a^-1. The net primary productivity was closely correlated with climatic factors, but showed a time lag. The net primary productivity of Pinus sylvestris var. mongolica plantation was significantly correlated with the monthly precipitation in August and December of the previous year and that in March of the current year. A positive correlation was found between the net primary productivity and the air relative humidity from August to September in the previous year and the current year. There was negative correlation between net primary productivity and the monthly temperature. In particular, the temperature in June-September of both previous and current year significantly affected the net primary productivity. Generally, the net primary productivity of Pinus sylvestris var. mongolica plantation was affected by temperature and precipitation, but was more sensitive to temperature. It may imply a decrease of the net productivity of the Pinus sylvestris var. mongolica plantations in the future due to possible climate warming in the Hulunbuir sandy land region.