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首页> 外文期刊>Forest Ecology and Management >Understorey plant community characteristics and natural hardwood regeneration under three partial harvest treatments applied in a northern red oak (Quercus rubra L.) stand in the Great Lakes-St. Lawrence forest region of Canada
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Understorey plant community characteristics and natural hardwood regeneration under three partial harvest treatments applied in a northern red oak (Quercus rubra L.) stand in the Great Lakes-St. Lawrence forest region of Canada

机译：在大湖区圣约翰湖北麓的红橡树（栎木）中进行了三种局部采伐处理后，地下植物群落特征和天然硬木再生。加拿大劳伦斯森林地区

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摘要

Throughout eastern North America, stands of northern red oak (Quercus rubra L.) are undergoing successional replacement by shade-tolerant competitors. In the Great Lakes-St. Lawrence (GLSL) forest region, Q. rubra approaches the northern limit of its distribution, and ecosystem-specific silvicultural directives are needed to promote regeneration. We used an inductive, ordination-based approach to explore patterns in understorey plant community composition and microenvironment under different partial harvest treatments applied in a GLSL hardwood stand, and related these to characteristics of natural seedlings of Q. rubra and its competitors Acer rubrum and Acer saccharum. Two years after harvest, we established 2mx2m plots in a stratified random design under 70% (n=20) and 50% (n=19) crown closure uniform shelterwood, group selection (n=15), and uncut upper slope (n=10) and lower slope (n=10) areas. Percent cover of understorey vascular plant species, and a suite of microclimatic and edaphic variables were measured in each plot. Density, mean diameter and mean height of seedlings in the understorey (height <1m) were determined in each plot for Q. rubra, A. rubrum and A. saccharum. Correspondence analysis (CA) ordination extracted two major axes explaining 21.6% of the total inertia in the species cover by plot matrix. Axis one separated uncut plots from the 50% shelterwood along a gradient of canopy cover associated with partial harvest treatments. Plot scores on axis one (13.2%) reflected a shift in dominance of the understorey from shade-tolerant Acer spp. to shade-intolerant colonizers, Rubus idaeus and Carex spp. Plot scores on axis one were directly (p<0.05) associated with total understorey plant cover, litter depth, soil temperature and pH, but not with measures of plant diversity. Axis two (8.4%) separated plots from upper slope and lower slope areas, and plot scores were inversely associated (p<0.05) with soil pH, phosphorus and nitrogen levels. Along axis two there was a shift in dominance from competitive (e.g. A. saccharum) to stress-tolerant (e.g. A. rubrum) species as soil fertility declined. Stepwise linear regression indicated seedling diameter in Q. rubra, A. rubrum and A. saccharum was inversely related to canopy cover. This suggests all three species benefited from partial harvest, although the relationship was strongest in Q. rubra. Patterns in understorey composition, microenvironment and seedling characteristics provide the basis to identify the main competitors of Q. rubra seedlings and adjust regeneration efforts along gradients of canopy closure and soil fertility under partial harvest systems within the GLSL forest region.
机译：在整个北美东部，北部赤栎（栎栎）的林分正逐渐被耐荫的竞争对手所取代。在大湖区-圣劳伦斯（GLSL）森林地区Q. rubra接近其分布的北限，因此需要特定于生态系统的造林指令来促进再生。我们使用归纳法基于排序的方法来探索在GLSL硬木林分上应用的不同部分收获处理下的下层植物群落组成和微环境的模式，并将其与Q.rubra及其竞争对手Acer rubrum和Acer的天然幼苗的特性相关联糖精。收获两年后，我们采用分层随机设计在70％（n = 20）和50％（n = 19）冠闭合均匀遮盖木，群体选择（n = 15）和未切割的上坡度（n = 10）和较低坡度（n = 10）的区域。在每个样地中，测量了下层维管植物物种的覆盖率，以及一系列微气候和水生变量。在Q. rubra，A。rubrum和A. saccharum的每个样地中，确定地下层中幼苗的密度，平均直径和平均高度（高度<1m）。对应分析（CA）排序提取了两个主轴，通过图矩阵解释了物种总惯性的21.6％。第一个轴沿与部分收获处理相关的树冠覆盖梯度，将未切割的地块与50％的防护林分开。第一轴上的地块得分（13.2％）反映了底层的优势从耐荫的宏cer树种的转变。遮荫不耐的定居者，即悬钩子（Rubus idaeus）和Carex spp。第一轴上的地标得分与底层植物总覆盖率，凋落物深度，土壤温度和pH值直接相关（p <0.05），但与植物多样性的测量结果无关。第二轴（8.4％）从高坡度和低坡度区域分离出样地，样地得分与土壤pH，磷和氮水平呈负相关（p <0.05）。沿着第二轴，随着土壤肥力的下降，优势物种从竞争性物种（例如，糖精）转变为耐胁迫性（例如红树）。逐步线性回归表明Q. rubra，A。rubrum和A. saccharum的幼苗直径与冠层覆盖率成反比。这表明所有三个物种都受益于部分收获，尽管这种关系在Q. rubra中最强。下层组成，微环境和幼苗特征的模式为确定GLSL森林区域内部分收割系统下红树芥菜幼苗的主要竞争者并根据冠层封闭和土壤肥力的梯度调整再生努力提供了基础。

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