哀牢山黄心树幼苗人工控制实验生长特征

为探究哀牢山国家自然保护区常绿阔叶林优势树种黄心树幼苗的生境选择特征,将其幼苗分别移栽到森林生境及人工遮阳生境中,对其相关生长指标和气体交换参数进行了测定,结果表明,黄心树幼苗具有较好的耐阴性,在低光条件下能保持较高的存活率。林窗中心的黄心树生长指标显著高于林冠下,在林窗中心,更有利于黄心树幼苗的存活及生长。土壤含水量是影响黄心树幼苗存活率及其生长的主要因素,较高的土壤含水量有利于黄心树幼苗的定居和生长。光照强度是影响黄心树幼苗生长的重要因素,在一定的光照强度范围内,黄心树幼苗各项生长生理指标都随光照的增强而增大。黄心树幼苗在相近光照强度的人工遮阳环境中,比在自然森林生境中生长状况要好。但黄心树幼苗在较低的光照条件下,其生长对土壤水分含水量的变化不敏感。     

茶叶乌桕混交效益好

茶叶乌桕混交,能形成比较合理而稳定的群体结构,与纯茶园相比,更能充分利用空间,提高光能利用率。据浙江林学院试验,由于乌桕树冠的作用,混交茶园夏季光照强度比纯茶园降低50%,温度低2℃,空气相对湿度增加5—12%,土壤含水量增加1.37%,耕作     

林窗与凋落物对人工云杉林早期更新的影响

为阐明林窗和凋落物对云杉人工林更新的作用,在川西米亚罗人工云杉林制造林窗(40m2)。通过对林窗环境因子进行动态监测,并跟踪调查天然下种、人工播种和去凋落物播种3种方式的云杉种子萌发和幼苗存活情况,以及进行云杉凋落物水浸液对其种子萌发及根、茎生长影响的室内观察,对林窗与凋落物对云杉种子萌发和幼苗存活的影响进行研究。结果表明:林窗环境具有异质性;林窗位置以及播种方式对种子萌发和幼苗存活都有影响,天然下种(2.75株·m-2)和去凋落物播种(21.25株·m-2)均在林窗中心幼苗萌发数量最多,人工播种(10.75株·m-2)在林窗边缘种子萌发数量多;靠近林窗中心位置幼苗死亡率略低;3种播种方式以天然下种种子萌发数量最少,去凋落物播种最多。云杉凋落物水浸液对其种子萌发和幼苗生长均有显著抑制作用,对根和茎生长的抑制率分别是68.62%和66.39%。初步认为,林窗有利于森林更新;可采取人工播种措施促进更新;凋落物对云杉人工林更新产生不利影响。     

子午岭油松林林隙更新特征研究

利用样地调查资料,以林下为对照,分析研究子午岭油松林的林隙更新特征,结果表明:1)子午岭油松林林隙内和林下更新树种在组成和数量上有较大差异,其中,油松在林隙内的重要值远远大于其在林下的重要值,是林隙更新的主要树种;2)油松幼苗幼树在林隙内生长良好,7年生以上的幼树在林下分布已很少,地径在1.0cm以上、高度在50cm以上的幼树数量分布在林隙内也远远大于林下,说明随着年龄的增长,油松幼苗幼树在林隙内存活的概率大于林下;3)方差分析表明,油松幼苗幼树在林隙内与林下的高度生长差异极为显著;4)相关性分析表明,林隙内油松幼苗幼树的更新数量与光照强度呈显著正相关,与植被总盖度呈显著负相关。     

广东连州田心梅树冲伯乐树种群及其生境特征

伯乐树是国家Ⅰ级重点保护野生植物,其自然种群在广东连州田心梅树冲的个体数量较多。2013年用HOBO温湿度记录仪对其生境温湿度进行监测,同时测定土壤的理化特性、叶面光照强度、叶片生理生态特性、种群结构等,以分析伯乐树种群及其群落的生境特征。结果表明,生境2013年的年均气温17.356℃,年均相对湿度92.002％,符合中国伯乐树生境年均气温15℃以上,相对湿度80％以上的条件;土壤pH为6.38,有机质含量为0.50％,所测得的叶面光照强度小于旷地的10％。叶片SPAD值40.81-45.73,净光合速率3.53-4.07μmol/（m2·s）（以CO2计）,蒸腾速率0.90-1.40 mmol/（m2· s）（以H2O计）,水分利用效率2.91-3.92。2012年和2013年伯乐树种群为Poisson分布型;年龄结构、地径结构和树高结构均呈纺锤形,表明因受2008年初南岭地区冰雪灾害的影响,大树和更新层幼苗均受到破坏,为衰退种群。     

抚育间伐对燕山北部山地林内小气候的影响

为了探讨抚育间伐对林分小气候的影响,对燕山北部山地人工落叶松林和天然次生杨桦林的间伐区和未间伐区的林下照度、林内温度、空气相对湿度及不同深度的土壤温度进行了测定。结果表明:间伐区林分的林下照度明显大于未间伐区,前者为后者的4~5倍;间伐区浅层土壤温度明显大于未间伐区,间伐区与未间伐区土壤温度的差异随着土壤深度的增加而逐渐减小,15 cm以下土壤温度的差异消失;间伐区的林内气温与未间伐区没有明显差异;林内的空气相对湿度日进程呈"V"字型,间伐区和未间伐区之间空气相对湿度差异不明显。由此得出结论,抚育间伐对林分内的光照强度及浅层土壤温度有明显影响,并将对林分更新、林下植被发育及林地土壤的生物地球化学过程产生深远影响。     

巴山冷杉-牛皮桦混交林乔木更新及土壤化学性质对更新的影响

调查太白山巴山冷杉-牛皮桦混交林林下与林隙乔木更新及土壤化学性质,分析林隙及土壤化学性质对乔木更新的影响.结果表明:巴山冷杉-牛皮桦混交林乔木更新苗密度较小,为0.059株·m-2,但林下与林隙均以巴山冷杉更新苗为主;林下与林隙乔木更新苗密度差异不显著(P=0.160),但巴山冷杉幼苗密度表现为林隙内显著高于林下(P =0.012);相关分析表明,小林隙更利于巴山冷杉更新(r=- 0.397,P=0.030),而林隙大小对牛皮桦更新没有显著影响(r=0.125,P=0.511);在林下,土壤碱解N、全P含量和pH值与牛皮桦更新苗密度呈显著正相关;在林隙内,土壤全P和有效P含量与巴山冷杉更新苗密度呈显著负相关,全P含量与牛皮桦幼树密度呈显著负相关;林下土壤有机质含量、全N含量和有效P含量及林隙土壤pH值、有机质含量、全N含量和碱解N含量与牛皮桦和巴山冷杉更新苗密度均没有显著相关关系;林下土壤pH值显著高于林隙,而有机质、全N、碱解N、全P和有效P含量显著低于林隙.     

不同生境对木荷幼苗生长及幼树生物量分配的影响

在福建宁化国有林场开展了林下、小林窗和大林窗3种生境下木荷幼苗生长和6年生木荷幼树生物量分配特征的研究。结果表明,林下生长的木荷幼苗成活率显著高于小林窗和大林窗内的苗木;6年生木荷幼树平均树高和平均胸径在小林窗内最大,其次为大林窗,林下木荷幼树生长相对缓慢;林下生长的木荷幼树各营养器官生物量大小为干枝根叶,而大林窗和小林窗内各营养器官生物量的大小均为干根枝叶。在林下生境中,木荷采取保守生存策略,分配较多的生物量给枝叶用于获取更多光照;在林窗中,林木分配更多资源用于自身干物质积累,维持较高的生长速率。     

吉林蛟河针阔混交林乔木幼苗存活对密度和生境的响应

【目的】探究密度制约和生境过滤在群落、龄级和物种3个水平对幼苗存活的影响及相对重要性,为温带森林幼苗更新与物种多样性维持机制研究提供理论依据。【方法】基于对吉林蛟河针阔混交林209个幼苗监测样站连续3年(2016—2018)的动态监测及光照和土壤条件的测定,运用广义线性混合模型划分零模型、生物模型、生境模型和全模型4个模型,在群落、龄级和物种3个水平分析影响幼苗存活的因素及其相对重要性。【结果】2016—2018年累计调查到乔木幼苗共计3 970株,分属19种10科13属,其中重要值排名前5位的幼苗树种是水曲柳、紫椴、色木槭、红松和东北枫;至调查结束时(2018年9月),幼苗死亡数量共计2 644株,存活率4%;在群落水平上,幼苗存活率与异种幼苗邻体个体数、土壤有效钾和全磷含量均显著正相关(P005);在龄级水平上,不同年龄幼苗个体的存活对生物邻体和非生物环境因素的响应存在差异,当年生幼苗存活率与同种幼苗邻体密度和异种幼苗邻体密度均显著正相关(P005;P001),且与异种大树邻体胸高断面积之和显著负相关(P005),多年生幼苗存活率与生物邻体变量无显著相关性,而与土壤有效钾和全磷含量等非生物环境因素显著正相关(P005);在物种水平上,幼苗个体存活的影响因素表现出种间差异,水曲柳幼苗存活率与异种幼苗邻体个体数显著正相关(P005),色木槭的幼苗存活率与同种大树邻体胸高断面积之和显著负相关(P005),紫椴幼苗在土壤有效钾含量较高的生境中存活率更高,而红松幼苗偏好有效氮和有效磷含量较低的土壤环境。【结论】密度制约和生境过滤共同影响乔木幼苗存活,但其相对重要性随年龄和树种而变化。当年生幼苗存活主要受邻体的影响,而生境因素对多年生幼苗存活影响更显著。密度制约效应在吉林蛟河针阔混交林群落中得到验证,与土壤养分条件相关联的生境过滤作用对幼苗存活影响显著。在林分更新过程中需综合考虑幼苗个体存活影响因素的种间和龄级差异,在主要树种育苗及林下补植中需结合考虑不同树种偏好的生境因素进行适当管理。     

不同水分条件下天目琼花耗水特性

以天目琼花(Viburnum sargentii Koehne)幼苗为试验材料,采用盆栽控水法设置4个水分梯度,分别为田间最大持水量的95%(对照)、75%(轻度缺水)、55%(中度缺水)和35%(重度缺水),研究不同水分条件下天目琼花的耗水规律。结果表明:随着土壤含水量的降低,天目琼花的株高、单株叶面积、单株总鲜重和单株总干重显著减少。不同水分条件下天目琼花耗水量依次为水分充足轻度缺水中度缺水重度缺水,说明土壤含水量是决定植物耗水的主要因素。在不同水分条件下,白天耗水量占昼夜总耗水量的70%以上,说明主要耗水来自于白天。在水分充足、轻度缺水和中度缺水条件下天目琼花日均耗水量与温度和光照强度显著正相关,与相对湿度显著负相关,随着土壤含水量的降低,天目琼花耗水量与环境因子的相关性逐渐下降。在不同土壤水分条件下耗水和温度相关程度远大于光照强度和相对湿度,说明温度是影响耗水的主要气象因素。     

Effects of artificial shade on early performance of white spruce seedlings planted on clearcuts

Chlorophyll fluorescence, chlorophyll content, growth, and mortality of white spruce (Picea glauca [Moench] Voss) seedlings were monitored for 2 years after planting under three scenarios of artificial shade: no-shade (control), shade in summer only, and shade all year. The shade frames allowed 50–60% light transmission, with limited effects on air temperature, relative humidity, soil temperature, and soil moisture around seedlings. Based on fluorescence yield and chlorophyll content measurements, summer-only shade reduced photoinhibition and photooxidation, especially in summer and fall; extending to all year shading did not further reduce either photoinhibition or photooxidation. Shade tended to reduce seedling diameter and mortality, but after 2 years the cumulative effect on mortality was not statistically significant. Study results support the establishment of white spruce seedlings under partial forest canopy, especially on sites with harsh environmental conditions.     

长白山阔叶红松林隙内物种种间关系研究

对长白山阔叶红松林的林隙环境状况、林隙内物种种间关系进行了研究。结果表明:林隙与林内物种丰富度不同,乔木物种丰富度略高于林内,而灌木和草本物种丰富度则明显高于林内;林隙内物种种间关系多数呈负相关,极显著正相关(P<0.01)和显著正相关(P<0.05)种对数较少(乔、灌、草),极显著负相关(P<0.01)和显著负相关(P<0.05)种对数也较少(乔)或没有(灌、草),物种间主要表现为竞争关系;林隙中小气候状况发生了显著改变,光照强度和空气温度显著高于林内(P<0.01),空气相对湿度和地温变化规律也表现出显著变化。     

Characteristics of the Light Response in Seedlings and Saplings of Two Mid-Successional Species,Ash and Kalopanax,During the Early Stage of Regeneration in a Mature Forest

Abstract

Growth characteristics of ash (Fraxinus mandshuricavar. japonicd)and kalopanax (Kalopanax pictus), two mid-succcs-sional species, were monitored in relation to seasonal light in a deciduous broadleaf forest. During the growing, relative light intensity of the gap was 4 to 6 times higher than that under the closed canopy. Seedlings could be found on the mixed hardwood forest floor where relative light intensity was around greater than 7% of full sunlight. When saplings gap openings which had relative light intensities above 20%, they quickly developed lateral branches and increased their foliage volume. The light-photosynthesis curve of seedlings of both species showed a curve typical of the “shade leaf” type even though they grew under sunlight. In contrast, saplings of both species showed the “sun leaf” type of light-photosynthesis curve. This seedling to sapling shift from shade to sun adaptation was also found in other foliage characteristics. This study shows that species can efficiently adjust their leaf and branch characteristics to changing light environments from shade to openings in a forest.     

森林草原过渡带中沙地云杉幼苗在林窗中的环境梯度变化

在我国内蒙古自治区森林草原过渡带中,从林窗内到周围环境进行沙地云杉(Piceamongolica)幼苗的调查以阐明其梯度变化。在沙地森林区,选择了一个形成年龄长达30年的大林窗,从林窗中央向周围森林作2个5m宽的样带,对沙地云杉幼苗动态进行了监测。幼苗距离林窗中心越远,个体越高,数量也越多。在林窗内,有很多幼苗,但是大多数的幼苗在它们长大之前就死亡了。相对于林木高度的动态变化,幼苗的死亡率在样带中的分布基本上有着相似的规律。沿着森林的边缘,幼苗的生长可能由于林窗中边缘光线渗透而得到暂时的提高。文中还讨论了自然森林的更新动态。结果表明在沙地云杉林里林窗干扰带能产生一个非均质的环境促进物种的更新,从而决定了该森林是一个多年龄层次的森林类型。图6参37。     

An environmental gradient change of Picea mongolica seedling from the center of a forest canopy gap in forest-steppe ecotone in Inner Mongolia Autonomous Region of China

In sandy forest with a forest canopy gap for a period of over 30 years, the spruce（Picea mongolica） seedlings were monitored on two 5-m- wide transects from the center of a large gap into the surrounding forest. The farther they were to the far center, the taller grew the seedling and the more is the number of seedling. There were many seedlings under the canopy but almost all seedlings died before they grow up. Along the forest edge, growth of seedlings was temporarily enhanced by lateral penetration of light from the gap. The implications for natural forest regeneration dynamics are discussed. Our results prove that in P mongolica forest a gap disturbance creates a non-uniform environment for regeneration of the species, and determines that the forest was a non-even aged forest.     

Gap formation in Danish beech (Fagus sylvatica) forests of low management intensity: soil moisture and nitrate in soil solution

Soil moisture content (0–90 cm depth) and nitrate-nitrogen (NO₃-N) concentrations in soil solution (90 cm depth) were monitored after gap formation (diameter 15–18 m) in three Danish beech-dominated forests on nutrient-rich till soils. NO₃-N drainage losses were estimated by the water balance model WATBAL for one of the sites. Two forests were non-intervention forests (semi-natural and unmanaged), the third was subject to nature-based management. The study was intended to assess the range of effects of gap formation in forests of low management intensity. In the unmanaged and the nature-based managed forest, soil solution was collected for 5 years and soil moisture measured in the fourth year after gap formation. Average NO₃-N concentrations were significantly higher in the gaps (9.9 and 8.1 mg NO₃-N l⁻¹, respectively) than under closed canopy (0.2 mg l⁻¹). In the semi-natural forest, measurements were carried out up to 29 months after gap formation. Average NO₃-N concentrations in the gap were 19.3 mg NO₃-N l⁻¹. Gap formation alone did not account for this high level, as concentrations were high also under closed canopy (average 12.4 mg NO₃-N l⁻¹). However, the gap had significantly higher N concentrations when trees were in full leaf, and NO₃-N drainage losses were significantly increased in the gap. No losses occurred under closed canopy in growing seasons. Soil moisture was close to field capacity in all three gaps, but decreased under closed canopy in growing seasons. In the semi-natural forest, advanced regeneration and lateral closure of the gap affected soil moisture levels in the gap in the last year of the study.     

Regeneration dynamics of Sitka spruce in artificially created forest gaps

This study examined the variation in the development of naturally regenerated and planted seedlings of Sitka spruce (Picea sitchensis (Bong.) Carr.) within gaps cut in a 32-year-old stand of the same species. The circular gaps were 20 m in diameter and designed to allow sunlight into only half of the gap floor at midsummer given the latitude of 56°45′N. Eight plots (8 m × 3 m) were laid out along a north–south transect through each gap (four within the gap and two each under the closed canopy north and south of the gap). Each plot was sub-divided and seedlings were planted into one part and the other part was left to naturally regenerate. In subsequent seasons, plots were further subdivided into ‘weed free’ and ‘vegetation left untouched’. Results showed that while the two central plots within the gaps had the highest value of canopy openness, the highest accumulated temperature and lowest soil moisture were recorded in plots that received direct sunlight. However, level of germination was significantly higher in the shaded area of the gap than in the part that received direct sunshine suggesting that higher moisture levels in shaded areas are important to successful germination. Minimal germination was recorded in the plots beneath the canopy. Seedling survival was significantly influenced by the influx of competing vegetation, but only in the part of the gaps that received direct sunlight. The success of Sitka spruce regeneration within gaps appears to depend on sufficient moisture and light to support regeneration and early growth, but not too much light to encourage the development of competing vegetation. The permanently shaded areas of the gaps appeared to offer ground conditions with sufficient moisture and light to ensure successful germination and early growth of seedlings, but without excessive competition from other vegetation.     

Variation in canopy structure, light and soil nutrition across elevation of a Sri Lankan tropical rain forest

Mixed dipterocarp forests are perhaps the single most important rain forest type in the wet tropics. Only a few studies have purposefully examined differences in resource availability across mixed dipterocarp forest landscapes by simply measuring the abiotic variables of light, soil nutrition and soil water availability in relation to forest structure. We sought to directly measure the environment of canopy gaps across elevation and geology—from lowland mixed dipterocarp forest (100 m amsl) to lower montane dipterocarp forest (1200 m amsl) in southwest Sri Lanka. Middle elevation gap sites (300–900 m amsl) were subdivided into valley, mid-slope and ridge topographic positions. Eighteen natural disturbances all of which were canopy openings caused by tree fall, were randomly selected within primary rain forest that ranged across 100–1200 m elevation. Plots were placed in gap centers and in adjacent understories and measurements taken of forest structure (basal area, canopy height, canopy cover index, CCI), shade (light sensors—photosynthetically active radiation [PAR], canopy hemispherical photographs—global site factor [GSF]) and soil nutrition (pH, exchangeable Al, K, Mg and Ca; Total N; and plant available P). Soil moisture was measured at bi-weekly intervals for five years across middle elevation sites only (300–900 m amsl). Stand basal area, mean canopy height, and canopy cover index all declined with increase in elevation. Understory PAR and GSF decreased with increases in canopy height, basal area and CCI. Size of canopy opening decreased with increase in elevation, but PAR and GSF increased. Valley sites had significantly greater levels of mean percent soil water content as compared to mid-slope and ridge sites of middle elevation sites. However, at the onset of the southwest monsoons in May all sites were similar. Differences were most pronounced during the dry season (December–April). No differences in soil moisture content could be found between gap and understory microsites. K and Ca in gap centers and adjacent forest understories increased with increase in elevation and change in associated geology. pH increased and Al decreased with elevation and associated geology but only for forest understory conditions. Results demonstrate strong differentiation in soil and light resources with elevation that appears related to size of tree-fall disturbance, stature of the forest, topographic position and underlying geology and soil-weathering environment. This suggests that forest management and conservation practices need to develop and tailor techniques and treatments (silviculture) to the forest that emulate and/or account for change in elevation, geology and topographic position. Further studies are needed to identify which are the primary underlying mechanisms (e.g. temperature, wind, soil nutrients, soil moisture availability) defining change in forest structure across elevation.     

Effect of micro-environmental factors on natural regeneration of <Emphasis Type="Italic">Sal</Emphasis> (S<Emphasis Type="Italic">horea robusta</Emphasis>)

Micro-environmental factors viz., soil moisture and light intensity are important factors that affect natural regeneration in forests. These factors vary spatially depending on the overhead canopy density of the forest. The present study focused on studying the effect of variation of soil moisture and light intensity on natural regeneration of sal species (Shorea robusta) under different micro-environments due to overhead canopy of varying forest density. Experimental plots of 40m× 40m size were laid under different overhead canopy densities in a small sal forested watershed in the foot hills of Himalayas in Nainital District of Uttarakhand State, India. The plots were monitored on a long term basis for soil moisture at multi depths, light intensity and natural regeneration of sal. The results of the study revealed that the natural regeneration was highest under C1 (up to-0.30) canopy followed by C2 (0.30–0.50), and C3 (0.50–0.70) canopies. The C3 canopy showed the dying back of sal shoots over 4 years of study. The highest R² value of linear regression between incremental score of plot regeneration and average soil moisture content was obtained as 0.156 for average soil moisture content during non-monsoon months at 100 cm depth. The R² value between incremental score of plot regeneration and annual average light intensity was obtained as 0.688 which indicated that the regeneration is largely dependent on the light intensity conditions during the year. The multiple linear regression analysis between the incremental score of regeneration and the average light intensity and average soil moisture content revealed that that about 80% of variation in regeneration is explained by both the factors.     

油松人工林不同大小林隙环境因子差异性比较

【目的】油松Pinus tabulaeformis是我国北方地区主要造林树种。旨在阐明油松人工林抚育间伐24 a后形成的不同等级林隙间环境因子的差异,探讨林隙的形成对环境因子的影响以及环境因子间的相关关系。【方法】在油松人工纯林选择4种等级的林隙,即林隙直径和冠层平均树高(即林分平均高)之比分别为L-Ⅰ(0.75 H)、L-Ⅱ(1.00 H)和L-Ⅲ(1.25 H)(H为冠层均高)和对照(CK,林冠下),测量了生长旺季的环境因子(光合有效辐射、空气温度、空气湿度、土壤温度和土壤湿度),在此基础上,分析了不同林隙等级间和林隙内不同区域的环境因子的差异性以及环境因子间的相关关系。【结果】1)不同等级林隙间光合有效辐射和土壤温度均达到了显著差异(P <0.05),最大差值分别达到了167.94μmol/m^2s和0.7℃,且随着林隙面积的增大而增大。2)3个面积等级的不同区域间光合有效辐射均表现出了显著的差异,土壤温度仅在L-Ⅱ面积等级林隙中达到了显著差异(P <0.05),在林隙中心区域光合有效辐射和土壤温度具有最大值。3)除了L-Ⅲ面积林隙等级外,其余的林隙等级和对照内光合有效辐射与土壤温度之间均有显著的正相关性(P <0.05)。【结论】在油松人工林内,抚育间伐24 a后,间伐产生的不同等级林隙和林隙区域会对光合有效辐射与土壤温度产生显著影响,对其他环境因子的影响不大。