不同人工林林下幼苗更新特性研究

[目的]探究阔叶混交林的更新特性。[方法]对红椎纯林、马尾松纯林、红椎+马尾松同龄混交林、红椎+马尾松异龄混交林4种林分设置固定样地进行幼苗更新研究。[结果]红锥与马尾松同龄混交林下幼苗物种数量及个体数均远高于各自的纯林及异龄混交林分;各林分自然更新显示物种数、个体数稀少特征;固定幼苗样方分析表明,红椎纯林和同龄混交林幼苗在不同坡位差异显著,而马尾松纯林和异龄混交林幼苗的个体数在不同坡位差异不显著;间伐因素对同龄混交林和异龄混交林的幼苗物种数影响显著,去除凋落物能显著增加红椎纯林和同龄混交林林下幼苗的物种数。[结论]结果为阔叶混交林的培育和更新研究提供了参考。     

不同坡位杉木—闽粤栲混交林及杉木纯林养分循环特征的比较

选择福建省建阳范桥国有林场16 a生杉木—闽粤栲混交林与杉木纯林为研究对象,进行不同坡位不同林分养分循环特征的比较分析,结果表明：杉木—闽粤栲混交林与杉木纯林养分存留量差异明显,混交林中坡和下坡分别比杉木纯林高28.16%、19.39%;各个坡位养分归还量均表现为：混交林〉杉木纯林,混交林下坡的养分归还量最大,其次是上坡,再次为中坡;中坡和下坡养分吸收量分别是杉木纯林的1.29、1.49倍;同一坡位同一林分的养分归还比表现为：N〉P〉K,说明养分N在两林分中的循环能力最强。混交林在上、下坡的归还比分别比杉木纯林高160.0%、104.55%,而二者在中坡的差异则较不明显,混交林养分归还比表现为：下坡〉上坡〉中坡,说明混交林下坡的养分循环能力最强。     

Leaf litter decomposition and diversity of arthropod decomposers in tropical <Emphasis Type="Italic">Muyong</Emphasis> forest in Banaue,Philippines

The Muyong forest, an indigenous secondary forest in Banaue, Ifugao, Philippines, plays a crucial role in the Muyong–Payoh system, a continuum of secondary forest and rice terrace, of the Banaue rice terraces by providing water and nutrients to the rice plants in the Payoh terraces. In recent decades, the planting of introduced tree species in the Muyong forest has threatened the sustainable provision of ecosystem services such as water balance and nutrient cycling. To further understand nutrient cycling in the Muyong–Payoh systems, this study was conducted in Poitan, Banaue, Ifugao to gather preliminary baseline data on floral diversity, leaf litterfall rate, leaf litter decomposition rate, and diversity and succession of arthropods in decomposing leaf litter in a Muyong forest. Vegetation analysis was done by identifying and describing the trees growing inside the five 10 m × 10 m quadrat sampling plots. Monthly leaf litter fall was collected in 1 m × 1 m litter traps, and the dry weight was determined after oven-drying at 65 °C for 48 h. Leaf litter decomposition experiment was established by laying out 12 nylon mesh bags containing fresh leaf litter in each of the four sites on the forest floor and one bag was retrieved every month to determine the change in dry weight of the leaf litter. Six bulk soil samples were collected from the Muyong forest floor and analyzed for organic matter, pH, available P and exchangeable K. Fresh leaf litter samples were analyzed for total N, P and K contents. Arthropods in the collected decomposing leaf litter were extracted using Berlese funnel and later identified up to families level using arthropod taxonomic key. The diversity of plants in the Muyong forest includes thirty-eight tree species belonging to 19 families dominated by indigenous tree species. Results showed that the monthly leaf litter fall was higher during the dry months of March to May and lower during the wet months. The estimated total leaf litter fall in Muyong forest was comparable to published litter fall from tropical secondary forests. The N, P and K contents of fresh leaf litter range from 1.0 to 1.2, 0.11 and 0.40%, respectively. The first month of decomposition has the fastest rate while the decomposition rate during the next 4 months ranged from 0.125 to 0.251. Complete decomposition or mass lost in the leaf litter in the Muyong forest took place within 5 months. The soil arthropods identified in the decomposing leaf litter were composed of 13 orders and 28 families. Majority of the collected arthropods were insects while other species including mites, spiders, millipedes and sowbugs were also present. Detrivore and fungivore Families were found to be dominant in the decomposing leaf litter. Moreover, the composition and succession of arthropod decomposer community varied in the three sampling methods and with the changing quality of the litter material as decomposition progressed. The wide diversity and succession of leaf litter decomposers consisting of detritivores, predators, fungivore and herbivore coupled with abundant rainfall and warm temperature are the two main factors that contribute to the fast rate of leaf litter decomposition and nutrient turn over in the Muyong forest. Thus, the Muyong forest can sustain the productivity of rice planted in the adjoining downstream Payoh terraces. Hence, the conservation and management of the Muyong forest is critical in maintaining the ecological functions of the Muyong–Payoh continuum.     

闽北不同类型毛竹林生态系统植被状况对地表径流的影响

以中亚热带杉木纯林（Ⅰ）和常绿阔叶林（Ⅴ）为对照，运用灰色关联法对闽北地区竹杉混交林（Ⅱ）、毛竹纯林（Ⅲ）、竹阔混交林（Ⅳ）3种不同类型毛竹林的生态系统植被状况影响地表径流系数进行了定量分析。结果表明，植被状况参数对地表径流系数影响的大小顺序是：草本层盖度＞凋落物层有效持水量＞物种丰富度＞林分高度＞凋落物总储量＞土壤稳渗速率＞灌木层盖度＞乔木层郁闭度＞土壤层有效持水量=土壤孔隙度；5种林分的植被状况对地表径流系数的影响以常绿阔叶林最大，竹杉混交林对地表径流的影响最小，灰关联度排序为：常绿阔叶林（0.763）＞杉木纯林（0.756）＞竹阔混交林（0.697）＞毛竹纯林（0.621）＞竹杉混交林（0.529）。     

海南岛东南沿海地区不同森林类型林地凋落物现存量和养分特征

为揭示热带沿海地区不同森林类型凋落物现存量及其养分元素储存能力的差异,选取林地相邻、生境条件基本一致的青皮林和木麻黄林为研究对象,设置随机样地,采集未分解层、半分解层、已分解层凋落物样品,测定凋落物层现存量和主要养分元素含量、储量及其释放率。结果表明：（1）木麻黄林凋落物层现存量为29.49 t/hm²,是青皮林的2倍,2种林型不同分解层表现为：已分解层>半分解层>未分解层;（2）2种林型不同分解层养分元素含量基本遵循C>N>Mg>K>P的变化模式,随着凋落物分解,青皮林各养分元素含量逐级降低,木麻黄林则因养分元素不同而异,可能因凋落物C含量流失过多出现损失速率大于分解释放养分速率而造成半分解层N、P、Mg的含量相对增加,但均在已分解层含量最低;（3）木麻黄林凋落物层养分储量值为8448.23 kg/hm²,是青皮林的2倍,各分解层凋落物养分元素的储量依次为C>N>Mg>K>P,与养分元素含量变化规律一致,而养分释放率从未分解层（-1.79%、-0.97%）到半分解层（0.65%、1.23%）呈现增加趋势。总之,同一立地条件下,不同林型的凋落物现存量、养分含量及其储量的差异可能与植物叶片生物学特征、微环境条件、微生物种群及活性不同有关。     

杉木纯林及杉桐混交林土壤酶活性研究

以3~5 a生杉木(Cunninghamia lanceolata)—千年桐(Aleurites montana)混交林与杉木纯林2种营造模式下不同土层(0~10、10~20、20~30 cm)土壤作为研究对象,探讨杉木纯林和杉桐混交林(Cunninghamia lanceolataAleurites montana mixed forest)的土壤脲酶(URE)、过氧化氢酶(CAT)、酸性磷酸酶(ACP)和蔗糖酶(INV)活性变化规律。结果表明:(1)在同一造林模式同一林龄不同土层间,4种酶在土壤表层含量最高,随着土层加深,各林下土壤ACP、URE和INV均呈明显下降趋势,CAT活性无差异性。(2)同一造林模式同一土层不同林龄间,杉木纯林和杉桐混交林土壤酶活性均随林龄的增大而变大,但不同酶的变化趋势不同。(3)同一林龄同一土层不同造林模式间,杉桐混交林的土壤ACP、URE及INV活性总体高于杉木纯林。(4)不同林地和土层的土壤酶活性之间存在着极显著的相关性(p<0.01)。混交模式下的林地土壤酶活性均高于杉木纯林模式,土壤生物学性质更加完善。     

海南岛不同类型滨海林地禁伐后的植被与土壤养分变化

滨海防护林及半自然次生林禁伐后的植被结构、土壤养分特征的变化,是认识林地演替生态过程和盐碱地生态恢复的核心内容,对生物多样性保护和生态系统服务功能提升具有重要意义。本研究针对海南岛北部低海拔滨海地区1994年开始禁伐的人工林与次生林,采用典型样地法,比较研究3类人工林（大叶相思林、木麻黄林、桉树林）和邻近的次生林、混交林（对照）等5个森林类型的植被与土壤养分特征。结果表明:（1）5种森林群落内主要植被共计34科54属57种,次生林和混交林群落物种组成较其他纯林物种丰富,木麻黄林内无灌木生长,除次生林外,其他森林类型草本层物种最丰富;（2）5种森林的土壤皆呈酸性,桉树林、次生林和混交林的土壤有机质和全氮含量较高,但土壤有效磷含量显著低于木麻黄林和大叶相思林（P<0.05）;（3）混交林土壤速效钾最高为11.27 mg/kg,其他森林类型均很低甚至未检出;（4）次生林土壤有机质含量、混交林土壤速效钾含量与群落物种组成呈正相关;土壤全氮含量与树龄、树高等呈正相关。因此,土壤养分随着禁伐时间增长而增加;桉树林具有较高的有机质和氮含量,但木麻黄林和大叶相思林的磷含量较高,次生混交林则有着较高的钾含量。     

热带滨海台地典型森林类型凋落物及土壤有机碳特征

以海南岛滨海台地5种典型森林植被为研究对象,利用标准地调查法对不同森林类型土壤有机碳含量、有机碳密度及单位面积有机碳储量的垂直分布特征进行比较分析,同时对不同森林类型凋落物及土壤表层细根的碳含量、碳密度和单位面积碳储量进行对比分析。结果表明:5种森林土壤有机碳含量介于1.79~10.60 g/kg之间,且随着土层深度的增加而降低;表层土壤(0~10 cm)有机碳密度和单位面积碳储量分别介于0.79~1.47 kg/m2和7.9~14.67 t/hm2之间;桉树林(2.11 t/hm2)和木麻黄林(1.73 t/hm2)凋落物单位面积碳储量高于其他3种林分;5种类型森林土壤表层细根单位面积碳储量介于0.29~0.47 t/hm2之间,木麻黄林最高(0.47 t/hm2),大叶相思林最低(0.29 t/hm2)。     

Spatiogenetic characteristics of beech stands with different degrees of autochthony

Background  

Autochthony in forest tree stands is characterized by a number of criteria, among which the range over which stands act as a population has been suggested to play a central role. Therefore, measures are needed for the delineation of populations or the detection of subpopulation structure. It is argued here that methods of population delineation must be based on the combined consideration of spatial distances and genetic differences between adult individuals. Conventional approaches and a set of newly developed methods are applied to seven isozyme loci in four beech stands which are distinguished by different types of forest management based on natural regeneration.     

Species diversity, seasonal dynamics, and vertical distribution of litter-dwelling thrips in an urban forest remnant of South china

Abstract Litter-dwelling thrips are an important component of soil macroinvertebrates in tropical and subtropical regions. However, little is known about assemblage composition, seasonal abundance and vertical distribution of litter-dwelling thrips. A survey of forest litter-dwelling thrips and other soil macroinvertebrates was conducted in an urban forest remnant at Guangzhou, China during 2004-2005 and 2008-2009. A total of 835 Tullgren samples were collected during the study. Thysanoptera constituted 6.5% of total litter-dwelling macroinvertebrate individuals extracted, representing three families, 19 genera, and 25 species. Psalidothrips ascitus Ananthakrishnan (Thysanoptera: Phlaeothripidae) and Hyidiothrips guangdongensis Wang, Tong and Zhang represented 78.5% of all individuals of litter-dwelling thrips during the survey. Numbers of species and density of leaf-litter thrips fluctuated between different months. Density of litter thrips increased from March until October, reaching a maximum of 41.1 individuals/m2 followed by a decrease. In January and February only a few larval thrips were present. Species diversity gradually increased from July (four species) to December (10 species), and then declined rapidly. The vertical distribution showed that the leaf-litter thrips species richness and abundance decreased significantly with soil depth; they were found only in the litter layer and upper soil layer (0-5 cm in depth) and were entirely absent in deeper soil layers. The results suggest that litter-dwelling thrips are a common group of litter invertebrates with high species diversity in subtropical regions. These urban forest remnants should be given special consideration in forest conservation planning, because of their significance as refugia for the litter invertebrate assemblages, especially for leaf-litter thrips.     

竹阔混交模式对毛竹出笋量的影响

通过研究不同混交树种、不同混交密度、不同混交方法对毛竹混交林出笋量的影响,结果表明：在以不同混交树种混交中,组合特性为落叶、喜光的出笋量最高,常绿、喜光的最低;以不同密度混交中,密度为150株·hm^-2的出笋量最高,毛竹纯林的最低;以不同混交方法混交中,块状混交的出笋量最高,毛竹纯林的最低。     

Relationship between competitive ability and yielding ability in mixtures and monocultures of populations of Dactylis glomerata L

Swards were developed from plants of contrasting populations of Dactylis glomerata L. selected for high and low dry-matter (DM) production in monocultures and mixed cultures grown during 1970 and 1971. DM production of these mono-genotype swards was assessed during 1974. Those swards developed from the divergent selections from monocultures maintained a significant difference between the high and low selections, whereas those developed from selections out of mixed cultures showed no significant difference in yield. These results are consistent with earlier reports that there is no positive relationship between competitive ability in mixed cultures and vigour in pure stands. The implications of the physiological basis of these responses in terms of grass breeding are discussed.     

Litter dynamics of Dactylis glomerata and Vicia villosa with respect to climatic and soil characteristics

The rates of litter decomposition, organic matter loss and nutrient release for Dactylis glomerata (Gramineae) and Vicia villosa (Leguminosae) were studied at two sites in north Greece, which differed in soil pH, soil particle distribution and nutrient availability.
Climate, soil characteristics and taxonomic plant differences affected the rates of litter decomposition. Litter loss was higher at site A (neutral soil) than at site B (acid soil). Organic matter loss was generally low. Dry weather affected both parameters. Nitrogen release from litter was higher for both species at site A. The rate of P and K release was higher in the neutral soil than in the acid soil for both species, while that of Ca for both species and of Mg for Vicia was higher in the acid soil. Phosphorus, Ca and Na release from the litter of the leguminous species began earlier than from the graminaceous species. P mineralization from Vicia litter seemed to start just after its incorporation into the soil.     

水稻品种混栽和单一栽培与稻瘟病的分布（英文）

 描述了稻瘟病害在寄主单一和混合栽培条件下的发生规律。研究表明,病害在各供试品种上的严重度与寄主的群体结构密切相关。在单一栽培的条件下,同一抗性遗传性的捕孢植株上的病害往往最重,而在不同抗性遗传特性的植株上的病害则明显下降。在混栽条件下相应的捕孢值株则明显减轻。这种现象说明,相同的垂直抗性基因能使亲和性病原菌小种群体得以增加,从而导致病害的严重流行。而在不同抗性基因的品种上,非亲和性的病原菌小种受到抑制,使病害趋于明显减轻。v     

贵州山区生态茶园不同凋落物木质素、纤维素分解特征

采用凋落物分解袋法,以贵州久安生态茶园内云南樟（Cinnamomum glanduliferum）、光皮桦（Betula luminifera）、杉木（Cunninghamia lanceolata）和马尾松（Pinus massoniana）叶凋落物以及茶树（Camellia sinensis）修剪物为研究对象,分析5种单一凋落物类型,以及9种混合凋落物类型（茶树-云南樟、茶树-马尾松、茶树-杉木、茶树-光皮桦、杉木-光皮桦、云南樟-光皮桦、云南樟-马尾松、云南樟-杉木、光皮桦-马尾松）分解速率和木质素、纤维素释放特征及差异性。结果表明,单一凋落物类型中,阔叶树种凋落物分解速率大于针叶树种;阔叶树种凋落物木质素含量总体上呈现增加趋势,而针叶树种总体上则呈现下降趋势;凋落物纤维素含量总体上呈现下降趋势。单一凋落物纤维素释放规律与混合凋落物纤维素释放一致,均为直接释放;单一凋落物木质素释放存在3种规律;混合凋落物木质素释放规律有5种。分析9种混合凋落物分解特征,44.4%的混合凋落物混合分解表现为加和效应,11.2%的混合分解表现为拮抗效应,44.4%的混合分解表现为协同效应;22.2%的混合凋落物木质素的释放表现为促进释放,55.6%的混合凋落物木质素释放表现为促进富集;22.2%的混合凋落物纤维素释放表现为促进释放;11.1%的混合凋落物纤维素释放表现为促进富集。研究结果可为维持茶园肥力提供理论依据。     

Certified Sebego seed stocks and seed piece treatments

The effects of several certified Sebago seed stocks on potato stands and yields were studied in 1969 and 1970 with a USDA maintenance stock used as a control. Seed piece treatments —(i) nontreated stem-end, (ii) nontreated bud-end, and (iii) Polyram®-treated bud-ends —were incorporated into the 1970 test. Large differences among certified seed stocks and seed piece treatment for stands and yields were obtained due to the bacterial seed piece decay and/or black leg disease caused byErwinia carotovora (Jones) Holland. Yields of the USDA maintenance stock were significantly superior to three and seven of the certified stocks compared in 1969 and 1970, respectively. While treatment of seed from vigorous stocks did not significantly increase yields, treatment of seed from less vigorous stocks did result in significantly greater yields. In the nontreated, less vigorous seed, there was a tendency for the bud-end seed to produce greater yield than the stem-end.     

Sowing date and nitrogen supply determine the outcome of competition between dallisgrass (Paspalum dilatatum Poir.) and tall fescue (Festuca arundinacea Schreb.) in the Pampas region of Argentina

The effects of sowing date and nitrogen (N) fertilizer on the inter‐specific competition between dallisgrass (Paspalum dilatatum Poir.) and tall fescue (Festuca arundinacea Schreb.) in the humid Pampas of Argentina were investigated in two pot experiments where a constant soil moisture content was maintained. Tall fescue and dallisgrass seeds were sown either in the spring (October 2000) or in the autumn (March 2001) in mixed and mono‐specific stands with 0 or 100 kg N ha^?1. In the spring, competition from tall fescue depressed dry‐matter (DM) yield of dallisgrass from 1·53 to 0·36 g DM per plant and tiller number from 9·4 to 3·7 tillers per plant in mixed and in mono‐specific stands, respectively, while tall fescue had 3–4 times higher DM yields in mixed stands. Leaf extension rate (LER) of tall fescue was higher (1·3 mm d^?1) than that of dallisgrass (0·53 mm d^?1). In the autumn, inter‐specific competition did not affect DM yield of dallisgrass and N fertilizer increased DM yield from 0·53 to 2·07 g DM per plant, tiller number from 6·8 to 14·2 tillers per plant and LER at the beginning of autumn from 1·2 to 2·12 mm d^?1 in both species. As temperature decreased, LER was reduced in both species to 0·31 mm d^?1 by late autumn. The number of leaves per tiller was not affected by treatment. Nitrogen fertilizer increased N concentration of above‐ground tissues of both species (18 g kg^?1 DM in autumn and 20 g kg^?1 DM in spring). It was concluded that a productive mixed pasture of dallisgrass and tall fescue can be obtained by sowing early in the autumn. The application of N fertilizer in this season is essential to ensure a high herbage yield and quality.     

Nitrogen concentration in the upper leaves of the canopy is a reliable indicator of plant N nutrition in both pure and mixed grassland swards

Effective indicators of plant nitrogen (N) nutrition are needed to improve N management in grasslands. This is particularly the case for mixtures that rely on N fixation by legumes as a major N input, because no reference tool such as the nitrogen nutrition index (NNI) exists under these conditions. The aims of this study were to test the reliability of a plant-based index, the N concentration of upper leaves in the canopy (Nup), as a possible alternative for NNI in both pure and mixed grasslands. Data were gathered from four experiments covering a range of pure and mixed grasslands under different N fertilization levels. A cross-validation of Nup predictions against NNI in pure stands, and against two NNI-derived indices in mixtures, was performed. The Nup values appeared to be linearly related to NNI in pure stands of both grasses and legumes. The relationship was identical for the two groups of species and explained up to 86% of NNI variability. In mixtures, Nup also displayed a linear relationship with the two other tested indices, explaining 65% and 78% of variability. The conclusions of the three indices diverged with respect to strongly unbalanced mixtures, where the assumptions regarding the computation of NNI-derived indices were not met. Excluding these situations, the overall relationship between Nup and NNI proved to be identical for mixtures and pure stands. The results suggest that Nup is a valid criterion for plant N nutrition which applies to a broad range of grassland species and to mixture conditions.     

海南橡胶林落叶特征研究

以海南幼龄和成龄橡胶林为对象,采用野外凋落框收集和关联分析等方法,研究2019年5月至2020年4月海南儋州区域橡胶林落叶特征和影响橡胶落叶的主要气候因子。研究结果表明:(1)海南橡胶林落叶产量呈"双峰"型动态变化,当年7月出现小峰,翌年3月出现最高峰;翌年2—4月为集中落叶期,该时期幼龄和成龄林分别占全年落叶总产量的73.04%和70.61%;成龄林落叶产量显著高于幼龄,增幅为14.77%。冗余分析表明,月均温度与月落叶产量呈极显著负相关关系,解释度为49.9%,贡献率为58.6%;(2)幼龄和成龄林间落叶C、N、P、K、Ca、Mg含量月动态变化趋势相似,各元素含量在秋冬季呈下降趋势,而冬春季出现养分富集的现象,年均含量在成龄和幼龄林间差异不显著;(3)落叶养分归还量月动态与落叶产量动态变化相似,受落叶月产量影响较大,而归还量受落叶产量和养分含量共同影响,落叶归还量表现为C>N>K、Ca>Mg>P,成龄显著高于幼龄,各元素增幅分别为16.3%、17.1%、16.7%、27.4%、15.3%和17.7%;(4)幼龄林各元素养分利用效率总体高于成龄林,其中幼龄钾素养分利用效率显著高于成龄(P<0.05);(5)月均温度是影响2019—2020年海南儋州橡胶林落叶格局的主要气候因子。该研究成果可为海南橡胶割胶制度以及养分管理提供技术支撑。     

间伐对楠木杉木混交林生长影响的研究

采用2个处理4次重复的完全随机区组设计对楠木与杉木混交林进行间伐试验研究,结果表明,间伐有利于楠木生长,间伐林分楠木平均胸径、树高和单株材积分别为不间伐的177．4％、120．8％和361．5％,间伐楠木林分蓄积量为74．23m^3·hm^-2,不间伐楠木蓄积量为24．88m^3·hm^-2,间伐楠木受光条件好,林木树冠大,生长好;间伐有利于楠木林下植被的生长,间伐林分林下植被生物量为9702．0kg·hm^-2,不间伐林分为3221．5kg·hm^-2,间伐林分为不间伐林分的301．2％;间伐后楠木林分的凋落物量有所减少,间伐林分凋落物量为2463．8kg·hm^-2,不间伐林分为3600．0kg·hm^-2,间伐林分为不间伐林分的68．4％。