Kinds Of Stands Research Articles

Diversity of understory birds in old stands of native and Eucalyptus plantations

We compared the vegetation structure between old (>70 year) stands of planted diversified native forests and stands of Eucalyptus tereticornis embedded in a mosaic of Eucalyptus stands. We then tested for differences in the abundance, species richness, species composition, and ecological traits (forest dependence, sensitivity to forest fragmentation, and diet) of the understory bird assemblages inhabiting both kinds of stands. We expected differences in the structure of the bird assemblages because of the different origins and management strategies (contrary to native stands, Eucalyptus stands were selectively logged in the past). Three stands of each habitat (native and Eucalyptus) were sampled with mist nets during 11 months. Eucalyptus stands had a denser understory, whereas native plantations had a more developed vertical structure and a greater density of native trees. The abundance distribution of bird species was more homogeneous in Eucalyptus than in native stands. Eucalyptus had slightly higher species richness (36 species) than native stands (32 species). The composition of species and the occurrence of the diet, forest dependence, and sensitivity to forest fragmentation categories were similar between habitats. Some bird species (e.g. Turdus leucomelas), however, were more abundant in one habitat over the other. Old stands of Eucalyptus and planted native forest can harbor a diverse bird community similar in structure but not exactly equivalent for individual bird species. Planting native diversified forests and keeping set‐aside stands of the exotic tree should be viewed as complementary rather than alternative strategies for maintaining bird diversity within plantations.

米槠人促更新林与杉木人工林叶片及凋落物溶解性有机物的数量和光谱学特征

PDF HTML阅读 XML下载 导出引用 引用提醒 米槠人促更新林与杉木人工林叶片及凋落物溶解性有机物的数量和光谱学特征 DOI: 10.5846/stxb201306101638 作者: 作者单位: 湿润亚热带山地生态国家重点实验室培育基地,湿润亚热带山地生态国家重点实验室培育基地,湿润亚热带山地生态国家重点实验室培育基地,湿润亚热带山地生态国家重点实验室培育基地,湿润亚热带山地生态国家重点实验室培育基地,湿润亚热带山地生态国家重点实验室培育基地,湿润亚热带山地生态国家重点实验室培育基地 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学青年基金项目（31100467）；国家自然科学基金项目（31070548）；福建省自然科学青年基金项目（2011J05105）；福建师范大学优秀青年骨干教师培养基金项目（fjsdky2012008） Quantities and spectral characteristics of DOM released from leaf and litterfall in Castanopsis carlesii forest and Cunninghamia lanceolata plantation Author: Affiliation: Fujian Normal University,,Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选取中亚热带米槠人促更新林（CCF）和杉木人工林（CLP）内的鲜叶、未分解层（L层）和半分解层（F层）凋落物为研究对象进行室内淋溶，对其淋溶液中的溶解性有机碳（DOC）、溶解性有机氮（DON）和溶解性有机磷（DOP）含量，紫外吸收值（SUVA），腐殖化指标（HIX）和红外光谱（FTIR）等进行了比较分析，以揭示其淋溶液中溶解性有机物（DOM）的数量和光谱学特征。结果表明：随着淋溶时间的增加，不同样品的DOM含量呈现先上升后下降，或者有波动的上升的趋势，这是因为DOM的释放和反吸附共同控制着DOM的含量。两林分中，F层凋落物DOM的SUVA值显著高于鲜叶和L层凋落物（P < 0.05）；从鲜叶到L层到F层凋落物，其HIX逐渐变大并且三者荧光强度最大值对应的波长由短波向长波移动，这是腐殖化程度越来越高、电子共轭体系逐渐增大的体现。两个林分6种样品的红外光谱显示了5个相似的吸收谱带，但不同样品各吸收带的相对比例不同，强度最大的吸收来自于H键键合的-OH的伸缩振动；同一林分内3种样品之间红外吸收的差异证明了鲜叶到L层再到F层凋落物，其DOM的芳香类物质含量逐渐升高，化学键力常数变小。总体上，与杉木人工林相比，米槠人促更新林的DOM养分含量更高，结构更复杂，因而更有利于有机质的积累。 Abstract:DOM (Dissolved Organic Matter) is the most reactive pool of organic matter in ecosystems. Among others, it is the energy source of most microbial metabolism. It also plays a key role in the biogeochemistry of C/N/P due to its high mobility. In forest ecosystems, the amount of DOM that is respired, accumulated in soils or leached from the ecosystems are highly dependent on its chemical nature, which may differ between types and species of litter. Castanopsis carlesii forest (CCF) and Cunninghamia lanceolata plantation (CLP) are of dominant forest type and distributed widely in Fujian province, mid-subtropical China. While previous work focused on the biomass and carbon storage of the two kinds of stands, information on DOM from fresh leaves and litterfall from the two kinds of stands is rare. In this study, laboratory leaching experiments were carried out for leachates from fresh leaves and litterfall in L and F layers, which are from a 36-year-old Castanopsis carlesii forest (CCF) by artificially promoted regeneration and a 37-year-old Cunninghamia lanceolata plantation (CLP) in Sanming, Fujian province. We examined the quantities and spectral characteristics of DOM in terms of Dissolved Organic Carbon (DOC), Dissolved Organic Nitrogen (DON) and Dissolvd Oganic Phosphorus (DOP) content, Special Ultraviolet-Visible Absorption (SUVA), Humication Index (HIX) and Fourier Transform Infrared (FTIR) spectroscopy. The results showed that during leaching, the DOC, DON and DOP content in different samples either reached their maximum first followed by a decreasement, or showed an increasing valley and peak cycle; this is because that the release and desorption of DOM both controled the content of DOM. The amount of total DOC from CCF is comparable to that from CLP, but the amounts of DON and DOP are much higher than those from CLF. In the two stands, SUVA value of the DOM from F layer were significantly higher than those of fresh leaf and L layer (P < 0.05), suggesting that F layer litter contains more aromatic substances. In the order of fresh leaf, litter in L layer and F layer, the HIX increased gradually and the maximum fluorescence intensity shifted from shorter to longer wavelengths, which can be explained by a higher humification degree and the presence of larger conjugated systems; also, DOM from CCF has higher HIX than that from CLP. Each of the six kinds of samples showed five IR absorption bands in common, i.e., 3758-3058 cm-1, 1630-1600 cm-1, 1420-1400 cm-1, 1080-1020 cm-1, 690-610 cm-1, whose relative intensities differed between samples, with the strongest absorption in all cases arising from stretching vibration of H-bonding hydroxyl groups. DOM from CCF is more carboxylic acid abundant than DOM from CLP. The infrared absorption differences between three kinds of samples in the same stand supported that the aromatic substance content gradually increased and conjugated systems growed larger from the fresh leaves to L layer litter to F layer litter. Overall, DOM from CCF is nutrient richer and bears more complex structures, thus favoring organic matter accumulation, when compared with DOM from CLP. 参考文献 相似文献 引证文献

Crossdating of disturbances by tree uprooting: Can treethrow microtopography persist for 6000 years?

Establishing disturbance frequencies in different types of forest ecosystems is an area of considerable research. We use several overlapping dating methods – robust repeated tree–censuses, dendrochronology and radiometric techniques (radionuclides 14C, 210Pb, 137Cs, 226Ra) – to date 302 pit-mounds, formed by uprooting, in 3 different forest ecosystems. Our research goal was to better understand the disturbance frequencies in these ecosystems and establish the potential longevity of treethrow mounds. At the same time, we tested the applicability of multiple dating methods in different kinds of stands, including two sites in Central Europe and one in the Great Lakes region, USA.We used tree-census data to establish the ages of the youngest (<37yr) uprooting events, 210Pb dating (including 137Cs and 226Ra) to date treethrow events younger than ca. 200years, dendrochronological dating for sites less than ca. 400years old, and radiocarbon dating for assumed older sites. In order to maximize the reliability of these age estimates, we compared the dates by evaluating different methods with maximal overlap – a method we call crossdating. Theoretically, our data provide (i) “minimum-limiting” ages of disturbance events, using dendrochronology, tree-censuses, 210Pb- and/or 14C-dating of samples from the organo-mineral sedimentation funnel within the treethrow pit, (ii) “real” ages of events, using dendrochronology, and/or (iii) “upper-real” or “maximum-limiting” ages of the events, using 14C-dating on remnants of uprooted trunks and charcoal from buried A-horizons in mounds.Responses in the radial growth of trees near by uprooting disturbances were usually detectable for 20years, and were specific to each region and tree species. Repeated tree-censuses (13,795 trees from 72.84ha) suggested that the ratio of bole breakages to uprootings was 2–3:1, and that the treethrow rotation period approximated 1250–1380years for some sites in Central Europe. At our European, beech-dominated sites, the maximal longevity of the treethrow microtopography was ca. 220years on the fine-textured Haplic Cambisols and exceeded 1700years on sandy-loam Entic Podzols. Finally, on the sand-textured Albic Podzols of northern Michigan, even greater longevities were achieved, with one mound returning a 14C age of 5260±30 BP (median of calibration age 4077 BC) – by far the oldest feature reported in the literature. Sedimentation rates in treethrow pits, calculated using the 210Pb technique, were 0.05–0.28cmyear−1 in the beech-dominated European forests, and 0.07–1.4cmyear−1 in the hardwoods of Michigan. Radiocarbon dating of fungal sclerotia in treethrow pits can also help inform the disturbance history.

Sensitivity of harvest decisions to errors in stand characteristics

In forest planning, the decision maker chooses for each stand a treatment schedule for a predefined planning period. The choice is based either on optimization calculations or on silvicultural guidelines. Schedules for individual stands are obtained using a growth simulator, where measured stand characteristics such as the basal area, mean diameter, site class and mean height are used as input variables. These characteristics include errors, however, which may lead to incorrect decisions. In this study, the aim is to study the sensitivity of harvest decisions to errors in a dataset of 157 stands. Correct schedules according to silvicultural guidelines were first determined using error-free data. Different amounts of errors were then generated to the stand-specific characteristics, and the treatment schedule was selected again using the erroneous data. The decision was defined as correct, if the type of harvest in these two schedules were similar, and if the timings deviated at maximum ±2 for thinning and ±3 years for clear-cut. The dependency of probability of correct decisions on stand characteristics and the degree of errors was then modelled. The proposed model can be used to determine the required level of measurement accuracy for each characteristics in different kinds of stands, with a given accuracy requirement for the timing of treatments. This information can further be utilized in selecting the most appropriate inventory method.

Aneuploidy in induced autotetraploid populations ofFestuca pratensis, Lolium multiflorum, and Lolium perenne IV. Competitive interactions between euploid and aneuploid plants in a simulated perennial sward of tetraploid Festuca pratensis

Klinga, K. 1987. Aneuploidy in induced autotetraploid populations of Festuca pratensis, Lolium muitiflorum, and Lolium perenne. IV. Competitive interactions between euploid and aneuploid plants in a simulated perennial sward of tetraploid Festuca pratensis. —Hereditas 107 249–256. Lund, Sweden. ISSN 0018–0661. Received August 5,1987 The competitive interactions in dense perennial stands of autotetraploid Fesruca pratensis were investigated by studying the following factors: (a) the persistence of euploid and aneuploid plants in pure stands and in mixtures; (b) the productivity of the persisting euploid and aneuploid plants in pure stands and mixtures; (c) the dry yield per unit area in the different kinds of growing regimes. About 80 % of the original euploid plants in the mixtures and about 50 % in the pure stands were left at the end of the experiment. The persistence of aneuploids did not differ between the two growing regimes. The aneuploid frequency changed from about 30 % to 20 % during the experimental period. In terms of persistence the euploids were better competitors, displayed by the significantly higher persistence in the mixtures. The yielding capacity and the competitive ability of individual euploids in the mixtures exceeded the aneuploids the year of planting and the first summer of the sward development. Later, the yielding capacity did not differ between the two chromosome categories. The negative agressivity values in the last year of the sward indicated a better competitive ability of the aneuploid plants. The presence of aneuploids in the mixed stands did not cause any conspicuous loss of yield. This was displayed by the lack of significant differences in the dry yield per unit area between the two kinds of stands.

Population levels and flight phenology of bark beetle predators in stands with and without previous infestations of the bark beetle Tomicus piniperda

Relative population levels and flight periods of Tomicus piniperda (L.) (Col.: Scolytidae) and two of its main predators, Thanasimus formicarius (L.) (Col.: Cleridae) and Rhizophagus depressus (F.) (Col.: Monotomidae) were monitored in 1995 in eight Scots pine stands in central Sweden using flight barrier traps (five per stand) baited with α-pinene and ethanol. In four of the stands (A-stands) T. piniperda and associated species had reproduced the previous year in stumps and slash remaining after thinnings conducted in the winter of 1993/1994. In the remaining four stands (B-stands) no bark beetle breeding material had been available during the five preceding years. In addition, the flight periods of the species were monitored in one stand in 1996. In 1995 the catches of T. piniperda and R. depressus were four to five times higher in the A-stands than in the B-stands, whereas there was no difference in the catch of T. formicarius between the two kinds of stands. The T. formicarius/ T. piniperda ratio was ca. 50 times higher in the B-stands compared with the A-stands during the period of clerid predation on colonising bark beetle adults and six times higher during the period of clerid oviposition. The R. depressus/ T. piniperda ratio was only slightly higher in the A-strands than in the B-stands as a result of the spatial distribution of T. piniperda. Three additional species of bark beetle predators were caught: Glischrochilus quadripunctatus (L.), Pityophagus ferrugineus (F.) (Col.: Nitidulidae) and Rhizophagus ferrugineus (Payk.) (Col.: Monotomidae). Based on their seasonal abundance the bark beetle predators can be divided into three temporal groups: the first species to occur in the spring is G. quadripunctatus, the second group consists of R. depressus and T. formicarius, and the last species to initiate flight are R. ferrugineus and P. ferrugineus.

African Visual Arts from a Social Perspective

The study of African art began in the first decade of this century. In looking back over more than 70 years of research, it is possible to discern a distinctive set of social science concerns, priorities, and modes of analysis. This social perspective depends not so much on disciplinary affiliation as on the kinds of stands taken on the nature of art and on the relative importance of culture as an explanatory principle in understanding its meaning. This paper is concerned with articulating the main models that have been utilized in social research on African art and with tracing their impact on the development of art studies. This historical account will also point out some of the most serious limitations of these models and will suggest studies which may lead to promising new directions. The focus of this review, then, will be on tracing the development of conceptual models with a social perspective. Studies with a social perspective include those which deal with the relationships among art, society and culture. These relationships can be conceived in a number of different ways, including, as Baxandall (1985: 89) succinctly suggests, “causality or significance or analogy or participation.” Such relationships are always a two-way street: not only do social practices and beliefs illuminate and affect art, but art also illuminates and affects social practice. Two essays will clarify the specific nature of the social perspective. Both classics in the field, both dealing with aesthetics, they are: “Yoruba Artistic Criticism” by Robert Farris Thompson (1973b) and “Principles of Opposition and Vitality in Fang Aesthetics” by James W. Fernandez (1966).