Leaf litter decomposition of canopy trees, bamboo and moss in a montane moist evergreen broad-leaved forest on Ailao Mountain, Yunnan, south-west China

Litter decomposition and nutrient release of selected dominant synusiae in an old-growth, evergreen, broad-leaved mossy forest on Ailao Mountain, Yunnan, south-west China, were studied over a 22-month period. The species studied were three dominant tall tree species, Lithocarpus xylocarpus Markg., Lithocarpus chintungensis Hsu et Qian and Castanopsis wattii A. Camus; one dominant understory species (the bamboo Sinarundinaria nitida Nakai); and a mixture of dominant mosses (including Homaliodendron scalpellifolium Fleisch, Symphyodon perrottetti Mont., Herberta longifolissa Steph. and Bazzania albicans Horik.). Fast initial litter decomposition was followed by lower rates. Decomposition rates of canopy species and bamboo leaf litter appear to be controlled by the initial concentration of lignin, nitrogen (N) and phosphorus (P) more than by morphological features of the leaves. The decay rate of moss litter was less correlated with nutrient composition and lignin concentration in initial mass. The order of decomposition rates was Castanopsis wattii > L. xylocarpus > L. chintungensis > bamboo > moss. The decomposition rate constants (k) of the leaf litter for the canopy species L. xylocarpus, L. chintungensis and Castanopsis wattii were 0.62, 0.50 and 0.64, respectively, and 0.40 and 0.22 for bamboo and moss, respectively. Turnover time (1/k) for the three canopy species was 1.61 years, 2.0 years and 1.55 years, respectively, and 2.50 years and 4.55 years for bamboo and moss, respectively. The N and P concentration in the decomposing leaf litter increased in the first 6 months and then decreased over the remaining period. There was a relatively rapid initial loss of potassium (K), followed by a slight increase. Each of calcium (Ca) and magnesium (Mg) decreased with time whereas iron (Fe) and manganese (Mn) increased with time to some extent. Nutrient release from decomposing leaf litter was in the order of K > Mg > Ca > N > P > Mn > Fe, except for bamboo (Sinarundinaria nitida) K > Ca > P > N > Mg > Mn > Fe.     

无菌容器湿润保存昆虫标本的方法

无菌容器湿润保存制作的昆虫标本虫体柔软 ,形态特征完好 ,克服了传统法制作的昆虫标本脆硬及易断的现象 ,适合于形态分类学研究。同时 ,也为昆虫学交叉学科提供了一种“天然”的试验材料。但此法不适于研究机构的野外综合考察及博物馆的较多昆虫标本保存 ,也不适用于鳞翅目、双翅目等类昆虫标本的制作保存。     

Species richness of Macrolepidoptera on Finnish deciduous trees and shrubs

Summary Species richness of Macrolepidoptera on Finnish trees and shrubs was analysed by means of stepwise regression analysis. The explaining variables were plant frequency, geographical range, plant height, number of relatives and leaf size.Total frequency of the host plant, which correlated strongly with range, explained 57% of the observed variance of lepidopteran species richness on deciduous trees and shrubs. Height of plant and number of relatives explained significantly the residual variation and altogether these three variables explained 71% of the variance of species richness.Analyses at the plant genus level gave similar results and frequency, height and number of relatives explained 78% of the variance of species richness of Macrolepidoptera on deciduous plant genera.When conifers were included in the analysis leaf size also becomes a significant variable. Leaf size can, however, act as a dummy variable which effectively distinguishes conifers from deciduous trees.The validity of different models explaining herbivore species richness on plants is discussed. The results of this study favoured more than earlier studies the importance of relatedness of host plants as a factor which determines the species richness of herbivores.     

亚热带3种树种凋落叶厚度对其分解速率及酶活性的影响

对中国亚热带树种杉木(Cunninghamia lanceolata)、香樟(Cinnamomum camphora)、银杏(Ginkgo biloba)3个树种在不同凋落物厚度下凋落物分解速率和分解酶活性进行了探究.利用分解网袋法,根据浙江省的平均酸雨水平,在酸雨(pH4.0)条件下设置了凋落物40g、凋落物20g、凋落物10g 3个梯度.结果表明:凋落物分解速率随厚度的增加呈加快的趋势,杉木凋落物10、20、40g的年分解系数K分别为0.24、0.27、0.34,香樟凋落物10、20、40g的年分解系数K分别为0.25、0.3、0.32,银杏凋落物10、20、40g的年分解系数K分别为0.42、0.5、0.58;脲酶活性表现为:凋落叶40g＞凋落叶20g＞凋落叶10g,纤维素酶活性表现为:凋落叶40g、凋落叶20g＞凋落叶10g,蔗糖酶活性表现为:后期凋落叶40g＞凋落叶20g＞凋落叶10g,凋落物分解过程是多种酶共同作用的结果.     

Effects of litter mixing on litter decomposition and soil properties along simulated invasion gradients of non-native trees

Plant and Soil - Phosphorus (P) is an essential macronutrient with major impacts on global crop productivity. Recent work showed that chlorophyll a fluorescence analysis can be used as a sensitive...     

Mating systems of two Bombacaceous trees of a neotropical moist forest

Summary A multilocus mixed mating model was used to analyze the mating systems of two tropical canopy trees in the Bombacaceae that differ in successional status and overall abundance. One population of each species was studied on Barro Colorado Island, Republic of Panama. Population outcrossing estimates of 0.57 and 0.35 from two years indicate a mixed-mating system with intermediate outcrossing levels for the gap-specialist Cavanillesia platanifolia, a relatively rare component of the island flora. Population and individual outcrossing estimates were associated with flowering tree density or degree of spatial isolation. Trees within clusters of flowering individuals have a higher degree of outcrossing than isolated trees. Annual estimates of individual tree outcrossing rates varied greatly as a function of flowering in its nearest neighbors. In contrast to C. platanifolia, Quararibea asterolepis was completely outcrossed and may be self incompatible. Maternal trees of both species had significantly heterogeneous pollen pools indicating non-random outcrossing. Apomixis by sporophytic agamospermy was rejected in C. platanifolia as contributing to the apparent selfing rate.     

Fruiting body formation of the nivicolous myxomycete Badhamia alpina in moist chamber culture

The plasmodium of Badhamia alpina thrived at lower temperatures (4 °C), and formed fruiting bodies at 8 °C. The yellow sclerotium and plasmodium were found inside a hollow, dead herbaceous stem under melting snow in Apr, and was cultured in moist chambers at 4 °C. The plasmodium did not form fruiting bodies for 6 wk at 4 °C. Sporulation was observed after the incubation temperatures rose to 8 °C. Sporulation occurred in the morning and cell cleavage at 11 a.m. The order of spore wall formation was observed by TEM for 12 h. The outer spore wall ornamentation was formed first followed by internal wall layers. Round electron transparent object was observed in the capillitium and peridium during the latter part of sporulation.     

Temporal patterns of water flux in trees and lianas in a Panamanian moist forest

Using constant heat sap flow sensors, xylem water fluxes in ten tree species and two liana species were monitored for 5–10 days during the beginning of the wet season in May, 1993. For a subset of the trees, a branch was also monitored at the top of the crown for 5 days. Xylem flux (J _S) was related diurnally in all plants to vapor pressure deficit (D) measured within the upper-third of the canopy, and to incoming shortwave radiation R _S above the canopy. Cross-correlation analysis was used to estimate time lags between diurnal patterns of J _S and D or R _S, and between J _S in stems and branches. The maximum correlation coefficient from cross-correlation of J _S with R _S (range=0.57–0.92) was often higher than the maximum of J _S with D (range=0.43–0.89), indicating that diurnal J _S was more dependent on R _S than D. Time lags (lag corresponding to maximum correlation) of J _S at stem-base with D was shorter (0–45 min) than with radiation (5–115 min), highly variable within a species, and uncorrelated to the height or exposure of tree crowns or liana in the canopy. On a stand level, not accounting for the diel lag between stem sap flux and canopy flux resulted in errors in estimated canopy transpiration of up to 30%. Received: 19 October 1998 / Accepted: 8 June 1999     

热带尖峰岭和亚热带千岛湖六种凋落叶的分解特征

选取亚热带6个树种马尾松(Pinus massoniana)、毛竹(Phyllostachys heterocycla)、水杉(Metasequoia glyptostroboides)、木荷(Schima superba)、青冈(Cyclobalanopsis glauca)和苏铁(Cycas revoluta)的凋落物,在亚热带的千岛湖和热带的尖峰岭进行凋落物分解实验,研究不同气候带下凋落物的分解特征。两样地的年均气温和降水为主要差异,年均温差达3.0℃。结果表明:两个样地凋落物的分解速率顺序为:毛竹﹥木荷﹥青冈﹥马尾松﹥水杉﹥苏铁,尖峰岭样地6个树种95%分解所需的时间集中在3.22-8.81a,千岛湖样地95%分解所需的时间为4.61-14.27a。6种凋落物叶的分解速率尖峰岭显著大于千岛湖(P0.05)。用尖峰岭的气候条件来模拟千岛湖气候变暖后的状况,凋落物分解的分解速率将提高43.08%-95.65%,凋落物的95%分解时间将缩短30.15%-48.85%。凋落物分解的表观Q10在3.30-9.35之间。在千岛湖样地凋落物的分解速率(k值)与初始氮含量呈显著正相关(P0.05),与木质素含量呈显著负相关(P0.05);在尖峰岭样地,凋落物的分解速率与凋落物基质质量的各因子相关性均不显著。氮含量和木质素含量在中亚热带地区是预测凋落物分解和失重的良好指标,在热带地区气候因子对凋落物分解的控制作用较强于凋落物初始基质质量的控制作用。     

Seasonal patterns in species richness of herbivores: Macrolepidopteran larvae on Finnish deciduous trees

Abstract. 1. The seasonal distribution of macrolepidopteran species richness on Finnish deciduous trees vaned from positively skewed (peak in spring) to negatively skewed (peak in autumn).
2. The skewness values of species richness had a significant negative correlation ( r = - 0.98) with the duration of the seasonal shoot-growth period of the tree species.
3. Trees which complete their shoot growth early in the season ( Quercus type) produce new leaves only during spring, while trees whose shoot growth continues to autumn ( Populus type) do so throughout the summer.
4. Consequently, there is a difference in the number of available resources in the late summer foliage of different tree species, Trees ceasing leaf production early such as oak ( Quercus robur ) and bird cherry ( Prunus padus ) have one major resource type (mature leaves) in late-season foliage while trees like birches and alders have two Ooung and mature leaves).
5. Because young leaves formed late in the season are preferred to mature ones by some species of herbivores and because other species prefer mature leaves at the same time, the species richness of Populus-type trees is higher later in the season than the species richness of Quercus-type of trees, which have just one type of resource available.     

黄土高原不同树种枯落叶混合分解效应

混交林中不同树种枯落物混合分解是否产生促进或抑制作用是评价种间关系和混交适宜性的重要依据之一。以黄土高原主要树种为对象,通过室内枯落叶混合分解模拟试验,结果表明:(1)沙棘、白榆、柠条和小叶杨枯落叶分解最快(周转期1 a左右),其次为旱柳、侧柏和白桦枯落叶(周转期略大于1 a),紫穗槐、辽东栎和刺槐枯落叶分解稍慢(周转期1.5 a左右),而樟子松、落叶松和油松枯落叶分解最慢(周转期略大于2 a)。(2)对于针叶树,与油松枯落叶混合,存在明显促进分解作用的是侧柏、落叶松,其次是白桦、沙棘和刺槐;与樟子松枯落叶混合,存在明显促进分解作用的是落叶松、侧柏、沙棘、白榆,其次是柠条、紫穗槐和小叶杨,而存在明显抑制分解作用的是刺槐,其次是白桦和辽东栎;与落叶松枯落叶混合,存在较明显促进分解作用的是白榆、白桦和辽东栎,存在较明显抑制作用的是刺槐;紫穗槐与侧柏枯落叶混合存在较明显的抑制分解作用。(3)对于阔叶树,与小叶杨枯落叶混合,存在较明显促进分解作用的是紫穗槐,其次是辽东栎和刺槐;与刺槐枯落叶混合,存在较明显促进分解作用的是白榆和沙棘,存在明显抑制分解作用的是柠条,其次是辽东栎和白桦;与白桦枯落叶混合,存在较明显促进分解作用的是辽东栎和紫穗槐,存在较明显抑制分解作用的是柠条;白榆与辽东栎、旱柳枯落叶混合均存在较明显的促进分解作用,而白榆与柠条枯落叶混合存在较明显的抑制分解作用;紫穗槐与旱柳、沙棘枯落叶混合均存在较明显的促进分解作用,而紫穗槐与柠条枯落叶混合有较明显的抑制作用。     

Directed isolation of Micromonospora generic cultures from moist soils and silts

The data on the study of various soils and substrates for isolation of Micromonospora from them are presented. It was shown that Micromonospora predominated in moist soils and especially in such substrates as silts where their content with respect to the all actinomycetous isolates amounted to 88.9 per cent. In the silts the content of Micromonospora amounted to 66.6--83 per cent, in the sopromely its content was 66 per cent, while in the ordinary non-moist soil its content was from 6 to 11 per cent. Predominance of Micromonospora in silts and moist soils makes its directed search possible.     

Density and distance-to-adult effects of a canker disease of trees in a moist tropical forest

We compared the spatial distribution of stem cankers on the canopy tree Ocotea whitei (Lauraceae) in a 20-ha plot on Barro Colorado Island, Panama, with spatial and temporal patterns of mortality in this host over the previous decade. The cankers occur both on adult and juvenile individuals, aothough juveniles are much more likely the adults to show symptoms. Disease incidence is host-density dependent, and both the presence of the disease and host mortality are more likely close to than far from a conspecific adult, which resulted in a net spatial shift of the juvenile population away from conspecific adults through time. Disease incidence is lower than expected among juveniles of O. whitei growing near to adults of the non-susceptible canopy tree Beilschmiedia pendula. The coincidence of spatial patterns of canker incidence and host mortality suggest a role for the disease in regulating host spatial distribution, in agreement with predictions of the Janzen-Connell hypothesis.     

黏菌生活周期不同阶段细胞核的观察

在显微和亚显微2个水平对黏菌孢子、原质团和菌核中细胞核进行了观察。试验结果表明,幼孢子中细胞核着色明显,原质团中细胞核在荧光染料染色的条件下易于被观察到,而菌核中的细胞核即使在电镜下也难以确定。     

Herbivory differentially alters plant litter dynamics of evergreen and deciduous trees

Here we propose that herbivore-induced changes in leaf litter quality can modify aboveground litterfall dynamics differentially in evergreen and deciduous trees. Because aboveground plant litterfall is an important source of nutrients in terrestrial ecosystems, any factor that alters plant litter quality can have large "afterlife" effects on the decomposition rate of that litter and the subsequent rate of nutrient release. Two contrasting patterns emerge from the literature and are corroborated by our two experimental case studies. First, in evergreens, herbivory commonly results in premature leaf abscission, improved litter "quality" and an acceleration of litter decomposition. Second, in deciduous trees, herbivory commonly results in the induction of secondary compounds that decelerates decomposition. We argue that these broad patterns reflect predictable differential responses to herbivores that can have important consequences for terrestrial nutrient cycling and productivity and that warrant more attention in the literature.     

Root growth and litter decomposition in a coffee plantation under shade trees

In a non-fertilized coffee plantation under shade trees the root biomass was excavated to estimate its distribution in the soil profile. One third of total fine (less than 1 mm) roots was found in the first 10 cm of soil; the cumulative total to 30 cm reached 73%. A highly variable and transient amount of fine roots colonized the litter layer. Root production both in the litter and in the first 7.5 cm of mineral soil was estimated from sequential samplings and was 10 g m^–2 yr^–1 and 660 g m^–2 yr^–1 respectively. The decomposition rate of weighed averages of litter fractions in the coffee plantation, calculated as the ratio of litter fall rate to the amount found in the soil was k=4.8. Shade tree leaves, the major component of litter descomposed slower than coffee leaves and these slower than flowers and fruits. Litter bag experiments showed considerable slower rates when mesh was 0.03 mm than 0.5 mm. Nitrogen and phosphorous showed increases in concentrations as decomposition progressed while potassium, calcium and magnesium followed a decrease in concentration that paralleled that of dry weight loss. In comparing the decomposition rate for litter with or without coffee roots growing in the bags, a tendency to show faster decomposition rates was found for the treatment with roots. These differences were however, only significant for one month for shade tree leaves litter. Nitrogen amounts remaining in shade tree leaves litter was lower in the treatment with roots that without roots. Potassium concentration in roots was positively correlated with potassium concentration in decomposing leaf litter where roots were growing. These results suggest that while roots growing attached to decomposing litter had little or no effect in speeding the decomposition process, the superficial roots seem to play an important role in absorbing very efficiently the mineralized nutrients from litter. The anatomical study of roots showed that the plantation is intensely infected with V-A mycorrhiza. External mycorrhizal hyphae did not to play a role in attachment of roots to decomposing litter while root hairs were found to grow in profusion on root surfaces oriented toward litter.     

真黏菌湿室培养研究进展

为丰富真黏菌物种多样性研究,综述了国内外不同时期真黏菌湿室培养的研究进展,通过梳理分类,对湿室培养获得的真黏菌物种进行统计分析。根据文献资料,1961年至今,在世界范围内通过湿室培养获得的黏菌新种有23种,隶属于6科10属,其中刺轴菌属Echinostelium 7种,其次为绒泡菌属Physarum 4种,盖碗菌属Perichaena 3种。湿室培养获得中国及其他国家的新记录种黏菌为147种,隶属于6目10科30属,其中绒泡菌属Physarum物种最多为20种,其次为无丝菌属Licea 17种。湿室培养主要用于真黏菌物种多样性、生态学和发育学的研究。在物种多样性研究中,湿室培养可以弥补野外采集标本的不足,获得因部分子实体微小、物候条件特殊、采集时间不适宜等情况下不易获得的物种,丰富所考察地区的黏菌物种种类,获得更多的黏菌资源。