阔叶红松混交林林隙凋落物分解-养分释放和他感作用对红松天然更新的影响

Vertical belt transects, running in West-East and North-South directionds, along the microenvironmental areas from gap center and gap edge to intact, continuous forest, will be established and corresponding sampling locations will be set up in different size of natural gaps in broadleaved Pinus koraiensis mixed forest by using uniform grids at coarse scale and fine nested scale. In each sampling locations, the spatiotemporal variations in microclimatic factors will be continuously monitored by using automatic weather stations, meanwhile the litterfall and soil samples will be collected periodically, through litter decomposition technique, GC-MS testing technique of allelopathety material compositions, spatiotemporal variations in allelopathety material compositions formed in the process of litter discomposition and their nutrient release will be analyzed, the effect of their synergy among microenvironmental factors, litter, and allelopathy material compositions on Pinus Koraiensis seed germination, seedling growth will be revealed. Quantitive relationship among litter decomposition rate, their nutrient release, allelopathety material compositions, soil nutrition, microenvironmental factors will be built, the effect of coupling mechanism among multiple factors on Pinus koraiensis regeneration will be explained. The scientific questions will be explored and discussed as follows: suitable gap microenvironment for Pinus koraiensis seed germination and seedling growth, wether there will be allelopathy material compositions in litterfall that can influence its seed germination and seedling growth. The objective of this study is to provide basic data and technique support for artifical simulated and promoted natural regeneration.

在阔叶红松混交林不同大小的天然林隙中，沿着林隙中心、林隙边缘和连续森林微环境梯度的区域，设置东西和南北走向的垂直样带，采用粗尺度和嵌套的细尺度均匀网格法布设采样点。在各采样点上，利用自动气象站等仪器，连续监测微气候因子的时空变化，同时定期采集凋落物和土壤样品，通过凋落物分解和他感作用物质成分的GC-MS鉴定技术，分析凋落物分解、养分释放和养分归还过程中产生的他感作用物质的时空变化，揭示微环境因子、凋落物及其他感作用物质的协同作用对红松种子萌发、幼苗生长的影响规律。构建凋落物分解速率、养分释放、他感作用物质、土壤养分与微气候因子之间的定量关系，阐释多因素耦合作用对红松更新影响的机制。探讨适于红松种子萌发、幼苗生长的林隙微环境，分析凋落物中是否含有影响种子发芽和幼苗生长的他感作用物质，将为人工模拟和促进红松天然更新提供基础数据和科技支撑。

红松（Pinus koraiensis）是我国东北东部山地地带性植被的优势树种，由于几十年来过度的采伐以及落后的森林经营等原因，导致阔叶红松混交林面积和蓄积锐减。因此，加快其生态系统的恢复和天然林的更新势在必行。.主要研究内容：（1）林隙微气候变化和红松更新状况分析；（2）红松枯叶分解动态与养分释放及化感作用物质成分分析；（3）红松、椴树、枫桦枯叶的化感作用；（4）林隙内凋落物分解—养分释放动态、化感作用与微气候因子、关键土壤肥力因子间的关系及其对红松种子萌发和前期幼苗生长的影响。.重要结果：（1）不同大小林隙由于光照不同，直接影响林隙内温度和湿度，从而影响地上乔木、灌木、草本植物的多样性，以及红松更新状况与幼苗生长；（2）大中小林隙之间，以及林隙内与郁闭林分（对照）相比，红松、椴树和枫桦凋落物分解速率，养分（N、P、Ca、Mg）释放与富集，以及有机酸、酚类物质含量差异显著；（3）发现低浓度（1:100）椴树枯叶浸提液对除苗高外的其他6个指标（发芽率、发芽势、胚轴和胚根长度以及根系总长和干质量）的促进作用最强，依次较对照显著提高 38.30%、37.84%、31.105、25.94%、61.34%、21.43%（P＜0.05）；低浓度（1:100）椴树鲜叶浸提液对苗高的促进作用最强，较对照显著提高15.13％（Ｐ＜0.05）；（4）椴树红松混交林TP、枫桦红松混交林BP、云冷杉红松林PAP林隙内更新总密度、幼树更新密度与郁闭林分差异显著（P<0.05），PAP林隙中更新总密度和幼树更新密度最高。BP林隙面积与更新密度相关不显著，乔木幼苗、幼树更新密度与有机质（R=-0.400，R=-0.475）、全氮均呈显著负相关（R=-0.519，R=-0.603）。TP林隙内全氮与乔木幼苗更新密度呈正相关（R=0.092），而与乔木幼树更新密度呈显著负相关（R=-0.585）。PAP林隙内全氮与乔木幼苗、幼树更新密度均呈负相关。郁闭林分幼苗更新密度分别与有机质、全氮、速效钾、pH值、脲酶和蛋白酶呈负相关。主成分分析表明，全氮是影响林隙和郁闭林分树木更新的关键因素。