不同带宽“带状皆伐”淡竹林的叶片生理特性及生产力比较研究

Leaf Physiological Characteristics and Productivity of Phyllostachys glauca Forest Applied with Different Widths of Strip Clear-cutting

【目的】从叶片生理特性视角,运用“源—汇”理论解释不同带宽(5,10,20 m)“带状皆伐”淡竹(Phyllostachys glauca)林生产力的差异,为竹林高效经营提供相关理论基础。【方法】采用随机区组法对淡竹林进行5,10,20 m带宽“带状皆伐”处理,测定各带宽留竹带和伐竹带竹子的叶片净光合速率(Pn)、蒸腾速率(Tr)、水分利用效率(WUE)、比叶面积(SLA)和N、P含量等生理指标,以及竹株大小和生物量等生产力指标;比较不同皆伐带宽竹林叶片生理和竹林生产力特征,并分析两者关系。【结果】(1)不同带宽留竹带与皆伐带的光合特性(Pn、Tr、WUE和SLA)相似,唯10 m皆伐带WUE显著低于其他带宽(P<0.05);在数值上,10 m留竹带的SLA最高,达(165.61±17.23)cm^(2)/g,10 m皆伐带的Pn、Tr最高;(2)对于叶片养分,整体上不同带宽的叶N含量无明显差异,留竹带以10 m宽的含量最低,而皆伐带以10 m宽最高;叶P含量整体随带宽增加而降低,5 m和10 m宽留竹带叶P均高于同宽皆伐带;(3)20 m宽留竹带新竹胸径和株高显著低于5 m和10 m带宽留竹带新竹(P<0.05);10 m宽留竹带和皆伐带生物量均比5 m和20 m带宽高;(4)作为“源”的留竹带和作为“汇”的皆伐带在叶片生理特性、新竹大小和生产力上均有明显差异;留竹带和皆伐带新竹个体生长均受皆伐带宽的负影响;比叶面积与留竹带新竹大小负相关,而与皆伐带新竹个体大小正相关;皆伐带叶片养分与竹林生产力的关系比留竹带密切。【结论】分析认为,10 m带宽竹林生产力比其他带宽高的原因主要是该带宽留竹带“源”的资源供应能较好满足新竹生长需求,同时新竹通过提升光合和养分生理性能进行适应生长,研究结果为竹林高效采伐提供了理论参考。

[Objective]From the perspective of leaf physiological characteristics,the“source-sink”theory was applied to explain the differences in productivity of Phyllostachys glauca forests under strip clearcutting method with different strip widths,thus providing a theoretical basis for efficient management of bamboo forests[.Method]A randomized group method was used to strip clear-cutting the P.glauca forests in 5 m,10 m and 20 m strip widths.Leaf physiological traits such as net photosynthetic rate(Pn),transpiration rate(Tr),water use efficiency(WUE),specific leaf area(SLA),N and P content,and productivity characteristics such as DBH,plant height,and biomass in the reserved and clear-cutting strips were determined.Leaf physiology and productivity characteristics of bamboo forests with different clear-cutting strip widths,and their interrelations were compared and analyzed.[Result]The results showed that:(1)Photosynthetic characteristics of reserved strips and clear-cutting strips with different bandwidths were similar,but the WUE of the 10 m strip clearcutting was significantly lower than that of other strip widths(P<0.05).The SLA of 10 m reserved strip was the highest,reaching(165.61±17.23)cm^(2)/g,while Pn and Tr of 10 m clear-cutting strip were the highest.(2)There were no significant differences in leaf N content with different strip widths.The leaf N content of 10 m strip width was the lowest in the reserved strips,while highest in clear-cutting strips.The leaf P content decreased with the increase of strip width(.3)Compared with 5 m and 10 m strip widths,the DBH and plant height of new bamboo with the 20 m strip width was reduced.The biomass in the 10 m strip width was higher than that of the 5 m and 20 m strip widths.(4)There were significant differences in the leaf physiological characteristics,new bamboo size,and productivity between the reserved strip as a“source”and the clear-cutting strip as a“sink”.The size of new bamboo in the reserved and the clear-cutting strips was significantly influenced by the cutting strip width.The SLA was negatively influenced by the size of new bamboo in the reserved strips and it was positively influenced by the size of new bamboo in the clear-cutting strips.The relationship between leaf nutrients and productivity of bamboo forests was more closely related in the reserved strip than that in the clearcutting strip[.Conclusion]The reason why the productivity of 10 m strip width bamboo forest is higher than that of other strip widths is that the resource supply of the‘source’of the 10m strip width can better meet the growth needs of new bamboos.At the same time,new bamboos adapt to growth by improving photosynthetic and nutrient physiological properties.The research results provide a theoretical reference for efficient harvesting of bamboo forests.