半干旱区引种樟子松生长的钙水耦合调控效应与机制研究—以辽西北为例

The introduced Pinus Sylvestris var. Mongolica is of great importance to ecological environment security in the semi-arid region of Northern China. However, under this region's natural environment conditions of calcium (Ca) rich and water shortage, the influence mechanism of Ca and water coupling to the growth of introduced P. Sylvestris var. Mongolica in this region has little known. Therefore, focusing on the growth of P. Sylvestris var. Mongolica in the semi-arid region of northwest Liaoning in this study, the characteristics and relations of Ca content and water use efficiency between different growth status of P. Sylvestris var. Mongolica will be investigated by regionally sampling leaf, wood and soil, and determining their Ca content and water use efficiency; Based on the controlled experiments with different Ca and water gradients, the response of Ca in leaf, water use efficiency, photosynthetic characteristics and the P. Sylvestris var. Mongolica growth on the Ca and water coupling will be examined to find out the suitable Ca and water coupling threshold for P. Sylvestris var. Mongolica growth, revealing the key role of Ca and water coupling to the growth of P. Sylvestris var. Mongolica; Through synthesizing the information of Ca, water, photosynthetic characteristics and the growth of P. Sylvestris var. Mongolica, a structural equation model will be built to fit the relations among them, elucidating the regulating effect and mechanism of Ca and water coupling to the growth of P. Sylvestris var. Mongolica combined with regional sampling results. These results will provide theoretical supports to the reasonable cultivation and the recession prevention of P. Sylvestris var. Mongolica plantations in the semi-arid region.

我国北方半干旱区引种樟子松对该区域生态环境安全意义重大。缺水和富钙是该区域自然环境的主要特点，然而钙水耦合对该区域引种樟子松生长的影响机理尚不清楚。因此本项目以辽西北半干旱区樟子松生长为研究对象，通过区域采集正常生长和衰退状态樟子松叶片、树芯及土壤样品，分析其钙含量和水分利用效率，明确该区域樟子松不同生长状态钙含量和水分利用效率的差异特征与关系；通过不同水分条件、不同钙浓度供给控制试验研究樟子松生长过程中叶片钙含量、水分利用效率、光合特性及樟子松生长指标对钙水耦合的响应，确定樟子松正常生长的适宜钙水耦合阈值，揭示钙水耦合对樟子松生长的关键作用；通过综合钙、水、光合特性和樟子松生长的综合信息，构建结构方程模型拟合它们之间的相互关系，结合区域采样结果阐明钙水耦合对樟子松生长的调控效应与机制。研究结果为半干旱区樟子松人工林合理培育与防止衰退提供理论支撑。

钙水耦合对樟子松生长的调控效应与机制的研究对半干旱区樟子松人工林合理培育与防止衰退意义重大。本项目以辽西北半干旱区樟子松生长为研究对象，通过区域采样，明确该区域不同生长状态下的樟子松钙含量和土壤碳氮、土壤微生物量碳氮、土壤微生物量熵与土壤呼吸速率差异特征；通过不同水分条件、不同钙浓度供给控制试验研究樟子松生长过程中樟子松生长、光合特性和抗逆性等指标对钙水耦合的响应；构建结构方程模型拟合它们之间的相互关系，阐明钙水耦合对樟子松生长的调控效应与机制。研究结果为半干旱区樟子松人工林合理培育与防止衰退提供理论支撑。.结果表明：.（1）衰退状态樟子松叶片水溶性钙含量均大于正常生长樟子松叶片水溶性钙含量；正常樟子松与衰退樟子松的土壤碳、氮、碳氮比及土壤微生物熵差异不显著；正常樟子松的土壤微生物量碳、氮显著高于衰退樟子松，而衰退樟子松微生物碳氮比与正常樟子松微生物碳氮比差异则不显著；正常土壤微生物熵略高于衰退樟子松，但二者相差不大；衰退樟子松呼吸速率显著高于正常樟子松。.（2）钙水耦合显著促进樟子松幼苗生长、光合特性和抗逆性，且在钙浓度为100 mg·kg-1,田间持水量为80%时达到最大值；当钙浓度一致时，樟子松幼苗的株高、基径、生物量、净光合速率、蒸腾速率、气孔导度、叶绿素含量、叶绿素荧光参数、可溶性糖、淀粉和抗氧化酶酶活性等指标随着水分梯度的增加而增加，水分利用效率呈现相反的结果；当在同一水分条件下，同样除了水分利用效率，其他上述指标均随着钙浓度的增加呈现先升高后降低的趋势，且钙浓度在50 mg·kg-1~200 mg·kg-1对樟子松幼苗的生长、光合特性和抗逆性均有积极的影响；叶绿素荧光参数表明当钙浓度为400 mg·kg-1时，对樟子松幼苗的生长产生胁迫。.（3）光合特性对樟子松生长产生直接影响，影响系数为0.96，而光合产物与抗逆性指标通过影响樟子松光合特性对其生长产生间接影响，影响系数分别为0.96和0.95。而光合特性、光合产物与抗逆性指标两两相关，相互影响，其系数分别为1，-0.99和-1。