白桦人工林抚育间伐试验研究

在海林林业局二十二林场1995年造的白桦人工林内,进行不同强度的间伐和修枝试验,该试验采用裂区试验设计,间伐设在主区,修枝设在副区,重复4次,共处理林分3·0hm2,考察间伐和修枝对白桦人工幼林生长的影响。     

白桦花期诱导技术的研究

在全光照(光合有效辐射尽可能保持在180μmolphotons·m-2·s-1以上)状态下,温度控制在25℃左右,湿度在60%以上,对塑料大棚中的白桦进行绞缢和CO2施肥处理,结果表明:绞缢是促进白桦提早开花的最有效措施,绞缢与对照两个水平间差异显著,绞缢开花率达38%,而对照开花率仅为2.9%。CO2施肥处理与绞缢处理之间不存在相互作用,CO2施肥不能明显使白桦提早开花。     

白桦强化促进提早开花结实技术的研究

在9年42次的前期试验的基础上，以1年生超级白桦苗为材料，通过5项配套强化措施(即适量CO2浓度、适当光照强度、适时绞缢、适宜催花素喷施和适中温湿度控制)的处理，实现了野外条件下17～20年开花结实的白桦，2～3年开花结实、4～5年规模结实。此外，建立了人工生态因子全息时序监测、显示、调控集成配套系统。     

白桦光合特性的研究

测定了3年生白桦的光合与呼吸作用对温度,湿度以及CO2浓度的响应;还测定了光补偿点,光饱和点和CO2补偿点。结果表明:在目前的空气CO2浓度下,光合和呼吸作用的最适温度分别是24℃和30℃;当相对湿度是80%时,白桦能维持较强的光合作用;呼吸作用与相对湿度无明显的相关性;光补偿点和光饱和点分别是25 molm-2s-1和1375 祄olm-2s-1;CO2补偿点是180 礚L-1;白桦在CO2浓度为2400 礚L-1时仍有吸收潜力。图4参19。     

营造白桦人工林最佳初植密度研究

冠幅与胸径呈正相关,初植密度直接影响到郁闭的早晚和郁闭时冠幅的大小,找出白桦经济成熟时的胸径与冠幅之间的相关关系,推断最佳初植密度。     

The unstable fate of seedlings of the small-seeded pioneer tree species, Betula maximowicziana

The dynamics of the seedling population of the pioneer tree, Betula maximowicziana, were studied for 6 years under various site conditions, with special reference to mortality and mortality factors, in order to better understand their seedling bank formation process. We found that current year seedlings suffered high annual mortality of more than 80%, but that mortality fell with age. Canopy covers and cohorts maintained strong influences on seedling mortality during the first 3 years after emergence. The open site with disturbed soil surface was best suited for 3-year seedling survival. Since the seedlings of B. maximowicziana emerged regardless of canopy covers, high seedling mortality was thought to be the main factor that interrupted their regeneration under a canopy. The occurrence of various hazards together caused high seedling mortality. The major mortality factors, regardless of site conditions, were drought, cold hazard and debilitation, though occurrence of the three factors varied, dependent upon the climate of that particular year. Annual mortality and the occurrence of each mortality factor at a fine scale of 0.2 m² quadrate each showed certain spatio-temporal variations within the same site condition. The extremely high mortality of B. maximowicziana seedlings should be attributed to their inherently small, initial size. The poor root system of the small seedlings may be responsible for their low resistance to various hazards, such as drought and frost heaving.     

Recovery of canopy trees and root collar sprout growth in response to changes in the condition of the parent tree after a fire in a cool-temperate forest

The relationship between the recovery of canopy trees after fire and root collar sprout dynamics was investigated during 1998–2000 in a secondary cool-temperate broad-leaved forest consisting of Quercus mongolica var. grosseserrata and Betula platyphylla var. japonica trees, in northern Hokkaido, Japan, which burned in April 1998. All of the Betula trees that were severely damaged, two-thirds of those slightly damaged, and half of those intact in 1998, died within three growing seasons after the fire. By contrast, half of the Quercus trees that were slightly damaged and half of those severely damaged recovered their foliage, and no slightly damaged or intact trees died during the three growing seasons after the fire. Many Betula trees developed several fruiting bodies of wood-destroying fungi on their stems, irrespective of damage severity. Fungi also infected some of the surviving Quercus, although the crowns tended to recover. Although many sprouting Betula were observed in 1998, the number of sprouts declined rapidly over the study period. Multiple regression analyses showed that the survival and growth of Betula sprouts were positively influenced by the number of sprouts in 1998, damage severity in 1998, and the degree of recover or decline during the study period, and were negatively influenced by parent tree size. On the other hand, a few sprouts of Quercus remained alive. Quercus remained dominant and the dominance of Betula was rapidly reduced after the fire. However, many Betula sprouts remained alive. Stand structure will change drastically for the time being.     

中国东北林区桦木属（Betula）分类探讨

许多学者先后对东北林区桦木属的分类进行了深入研究,对种及种下分类等级意见至今不一致,给综合开发利用桦木类群资源造成了混乱。笔者经多年深入林区实践、调查、采集标本,结合种群特征、地理分布、生境特点综合分类,不以蜡叶标本作为唯一依据,鉴定了桦木属种及种下等级,基本上同意傅沛云(1995)对东北林区桦木属的分类。但笔者认为东北白桦(B.mandshurica(Regel) Nakai)应视为独立种,取消栓皮白桦(Betula platyphylla Suk.var. phellodendroides Tung)名称及英吉里岳桦(ermanii Cham.var.yingkiliensis liou et Wang)名称,卵叶桦(Betula ovalifolia Rupr )不应该降为柴桦变种(Betula fruticosa Pall.),仍为独立种。图1表4参10。     

Two lignan rhamnosides from birch leaves

The extractives of shirakamba (Betula platyphylla Sukatchev var.japonica Hara) leaves were investigated. Two lignan glycosides were isolated, and their structures were elucidated to be 1-(4-hydroxy-3-methoxyphenyl)-2-[1-(3--l-rhamnopyranosyloxypropyl)-3-hydroxyphenoxy]-1,3-propanediol (I) and a new 2,3-dihydro-2-arylbenzofuran configuration neolignan,cis-2,3-dihydro-2-(4--l-rhamnopyranosyloxy-3-methoxyphenyl)-3-hydroxymethyl-7-hydroxy-5-benzofuranpropanol (II). These neolignan rhamnosides were newly found in shirakamba.     

白桦与山杨叶凋落物候的差异及其生态学意义

用凋落物收集法和凋落物候模型研究了白桦(Betula platyphylla)和山杨(Populus davidiana)的叶凋落物候。结果表明:白桦叶凋落显著早于山杨,凋落开始时间和凋落高峰分别比山杨早41和20 d,但它们的叶凋落结束时间基本相同,这导致白桦的凋落期比山杨长42 d。此外,白桦叶凋落集中程度也明显小于山杨,凋落峰值仅是山杨的五分之一。白桦的叶N质量分数较高,碳氮比较低,导致了白桦叶分解较山杨叶快。这体现了处于相同的环境条件,白桦和山杨在能量利用和养分循环方面可能具有不同的生态策略。