樟子松人工林热值与能量结构分析(Ⅱ)——凋落物的热值与能量动态和群落的能量净生产量与转化率

Heating Value and Energy Structure of Pinus sylvestris var. mongolica Plantation (Ⅱ):Heating Value and Energy Dynamics of Litters and Net Energy Yield and Conversion Efficiency of Communities

在生物量调查和热值测定的基础上,分析了24年生樟子松人工林凋落物的热值及能量季节动态、群落的净生产量及能量转化率。结果表明:林下植被凋落物的能量释放率高于樟子松凋落物的释放率,且凋落物释放量都主要集中在6、7、8月份。凋落物能量释放率以榆树枯叶和水曲柳叶最高,其他依次是樟子松枯叶>水曲柳叶梗>樟子松球果>樟子松树皮>樟子松枯枝。凋落物能量现存总量为205.49×109J/hm2;樟子松人工林群落能量年净生产量为344.45×109J/hm2,其中,樟子松林木能量年净生产量304.35×109J/(hm2.a),林下植被中能量净生产总量为40.10×109J/(hm2.a);能量累积比以樟子松人工林群落值最大,为7.44,其次是樟子松林木能量累积比为7.20,林下植被能量积累比最低;能量流动速率比为林下植被0.240>樟子松林木0.139>群落0.134;樟子松人工林群落的能量转化率为7.31%、樟子松林木和林下植被的能量转化率分别为6.46%和0.85%。

An experiment was conducted to study the heating value and soasonal dynamics of energy for litters and net yield and conversion efficiency of energy for communities in 24 year-old Pinus sylvestris vat. mongolica plantation based on biomass investigation and heating value test. Results show that the release rate of litters for understory plants is higher than that for pine trees, and the release peaks of litters for understory plants and pine trees concentrate in June, July and August. The leaf litters of Manchurian ash and elm have the highest release rate, and then followed by pine needle, Manchurian ash leaf stalk, pine fruit, pine bark and pine branch in sequence. The gross caloric value of litters is 205.49 ×10^9J/hm^2. The annual net accumulation of energy in the community is 344.45 ×10^9J/hm^2, among which 304.35×10^9J/（hm^2· a） come from pine trees and 10.10×10^9J/（hm^2· a） from understo：T plants. The energy accumulation coefficient of the community （7.44） is larger than that of pine trees （7.20）, and understory plants have the smallest energy accumulation coefficient. The flow rates and conversion efficiencies of energy for understory plants, pine trees and the community are 0.240, 0. 139, 0. 134 and 0.85%, 6.46%, 7.31%, respectively.