植被恢复树种在不同实验光环境下叶片气体交换的生态适应特点

比较研究了华南丘陵地区植被恢复8种乔木树种在不同光条件下的光饱和点、日平均净光合速率、叶温、气孔导度日平均值、内在水分利用效率和光合辐射利用效率等生理生态特征。结果表明,火力楠和藜蒴具有演替后期种的特征,在荫蔽条件下生存和生长良好,它们不宜用作构建先锋群落的树种。大叶相思、马占相思和樟树是典型的阳生性树种,具有鲜明的演替后期种的特征;红椎和海南红豆显示除叶温以外的阳生性的特征。这些种类可被选作构建先锋群落的组成成分。桂西红荷则只能作为演替的过渡种类,它兼具有演替前期种和演替后期种的特征,尤其适用于对先锋群落进行林分改造。     

A comparison of litter beetle assemblages (Coleoptera) in mature and recently clearfelled Eucalyptus obliqua forest

Abstract  This study compares litter-dwelling beetles in mature wet eucalypt forest with those in young forest regenerated following clearfelling. The aims of the study were to determine the extent to which these forest ages support differing litter beetle assemblages, and to identify species characteristic of each age. Beetles were collected with pitfall traps in a spatially replicated study design to avoid confounding forest age and site differences. Three transects of traps were located in each of mature and young forest stands at four study sites. Beetle abundance was greatest in young forest, and young and mature forest supported distinctly different beetle assemblages. Of 37 commonly collected species, an indicator species analysis found 9 species characteristic of young logging regeneration, and 7 species characteristic of mature unlogged forest. These species could be useful in other Tasmanian studies concerning forest management impacts. Only two significant indicator species were carabids, suggesting that focusing only on carabids as indicators of forest management may be undesirable.     

Responses of Pioneer and Later‐Successional Plant Assemblages to Created Microtopographic Variation and Soil Treatments in Riparian Forest Restoration

Riparian forest restoration generally involves introduction of later‐successional tree species, but poor species suitability to severely altered or degraded site conditions results in high mortality and poor community development. Additionally, while microtopographic heterogeneity plays a crucial role in the development of natural riparian forests, little is known regarding effects of restored or created microtopography on the development of introduced plant communities. The objective of this study was to determine the influence of created microtopography and soil treatments on early development of introduced pioneer and later‐successional plant communities in riparian forest restoration. Ridges, flats, and a mound‐and‐pool complex were created, and pioneer and later‐successional tree assemblages were planted within plots in each of these three microtopographic positions. Straw‐based erosion control mats were placed on half the plots as a source of mulch. After two growing seasons, growth and survival of the pioneer assemblage were equal among microtopographic positions, but survival of the later‐successional assemblage was significantly higher on ridges (59%) than on mounds and pools (22%) and flats (26%). A suitability index indicated that performance of the later‐successional assemblage on ridges was higher than that of the pioneer assemblage for all microtopographic positions. Flood duration explained much of the variation in plant assemblage survival, and erosion control mats had little influence on seedling survival. Restoring microtopographic features has the potential to enhance species survival and promote community development. Microtopographic restoration may be as important in riparian forest restoration as proper species selection and hydrologic reestablishment, especially at severely disturbed sites.     

清除优势草本植物对西双版纳飞机草-马唐群落中木本幼苗的影响

在农业弃耕地上通常会出现由草本植物占优势的演替早期群落。为研究优势草本植物对群落中木本幼苗及群落微环境的影响以及外来入侵植物和本地植物对木本幼苗的影响有何差异,在西双版纳地区选取由外来入侵植物飞机草和本地植物马唐共同占优势的演替早期群落,实施物种清除实验,观测样地中木本幼苗的高增长及死亡补充情况,同时对群落微环境进行观测。结果显示,清除优势种显著提高了木本幼苗的高增长,降低了其死亡率,并且使新增幼苗数量有所提高。清除优势种对0-50cm幼苗高增长和死亡率的影响均大于50-100(或200)cm幼苗。清除处理显著提高了样地的冠层下可见天空比例,但对土壤含水量和土壤养分的影响并不显著。飞机草和马唐均能形成浓密的冠层,通过对光的竞争抑制木本幼苗的生长,且这两者的抑制作用没有显著差异。该地区次生林中常见的先锋树种在研究样地内均有幼苗存在,但其生长却受到优势草本植物的强烈抑制。因此,对演替早期群落中草本植物的控制与管理应同时注意外来入侵物种与本地杂草。     

Seed Size,Seed Germination,and Seedling Survival of Brazilian Tropical Tree Species Differing in Successional Status1

Seed germination and seedling establishment patterns have been used to classify species as shade tolerant or intolerant. The main objective of this research was to investigate, under controlled conditions, seed germination of species from different successional positions as well as to follow seed germination and seedling survival under natural shade in the field. The species studied were Solarium granuloso‐leprosum, Trema micrantha, Cecropia pachystachya, Croton piptocalyx, Bauhinia forficata subsp. pruinosa. Senna macranthera, Schizolobium parahyba, Piptadenia gonoacantha, Chorisia speciosa, Pseudobombax grandiflorum, Ficus guaranitica, Esenbeckia leiocarpa, Pachystroma longifolium, Myroxylon peruiferum, and Hymenaea courbaril. Field trials were carried out at Santa Genebra Municipal Reserve, Campinas, SP, Brazil, at the forest edge and in the understory. No significant correlations were detected between successional status and seed size or seed water content. Light‐regulated germination was present only in small‐seeded species. In field experiments, most species, including the light‐sensitive ones, were able to germinate under the canopy, where a low red/far‐red ratio predominates. Most species, mainly those of early‐ and intermediate successional positions, presented low seedling survival rates under shade. Myroxylon peruiferum was the most shade tolerant species, while 5. granuloso‐leprosum, C. speciosa, P. gonoacantha, F. guaranitica, T. micrantha, and 5. parahyba were the most shade intolerant. These latter species showed little or no survival under the shade conditions.     

Comparative phylogeography of five widespread tree species: Insights into the history of western Amazonia

Various historical processes have been put forth as drivers of patterns in the spatial distribution of Amazonian trees and their population genetic variation. We tested whether five widespread tree species show congruent phylogeographic breaks and similar patterns of demographic expansion, which could be related to proposed Pleistocene refugia or the presence of geological arches in western Amazonia. We sampled Otoba parvifolia/glycycarpa (Myristicaceae), Clarisia biflora, Poulsenia armata, Ficus insipida (all Moraceae), and Jacaratia digitata (Caricaceae) across the western Amazon Basin. Plastid DNA (trnH–psbA; 674 individuals from 34 populations) and nuclear ribosomal internal transcribed spacers (ITS; 214 individuals from 30 populations) were sequenced to assess genetic diversity, genetic differentiation, population genetic structure, and demographic patterns. Overall genetic diversity for both markers varied among species, with higher values in populations of shade‐tolerant species than in pioneer species. Spatial analysis of molecular variance (SAMOVA) identified three genetically differentiated groups for the plastid marker for each species, but the areas of genetic differentiation were not concordant among species. Fewer SAMOVA groups were found for ITS, with no detectable genetic differentiation among populations in pioneers. The lack of spatially congruent phylogeographic breaks across species suggests no common biogeographic history of these Amazonian tree species. The idiosyncratic phylogeographic patterns of species could be due instead to species‐specific responses to geological and climatic changes. Population genetic patterns were similar among species with similar biological features, indicating that the ecological characteristics of species impact large‐scale phylogeography.     

Weed macaques: The evolutionary implications of macaque feeding ecology

Patterns of feeding ecology among the living macaques conform poorly with recognized phyletic distinctions within the genus because there is an important ecological division which cross-cuts phyletic groupings. This division, between weed species and non-weed species, is based on the differing abilities of macaques to tolerate and even prosper in close association with human settlements. Based on available information about their ecology in the wild, we tentatively assign macaque species to these two categories. Finally, we consider the implications of our argument for scenarios of the initial spread of the macaques.     

Does selective logging change ground‐dwelling beetle assemblages in a subtropical broad‐leafed forest of China?

Selective logging with natural regeneration is advocated as a near‐to‐nature strategy and has been implemented in many forested systems during the last decades. However, the efficiency of such practices for the maintenance of forest species are poorly understood. We compared the species richness, abundance and composition of ground‐dwelling beetles between selectively logged and unlogged forests to evaluate the possible effects of selective logging in a subtropical broad‐leafed forest in southeastern China. Using pitfall traps, beetles were sampled in two naturally regenerating stands after clearcuts (ca. 50 years old, stem‐exclusion stage: selectively logged 20 years ago) and two mature stands (> 80 years old, understory re‐initiation stage: selectively logged 50 years ago) during 2009 and 2010. Overall, selective logging had no significant effects on total beetle richness and abundance, but saproxylic species group and some abundant forest species significantly decreased in abundance in selectively logged plots compared with unlogged plots in mature stands. Beetle assemblages showed significant differences between selectively logged and unlogged plots in mature stands. Some environmental characteristics associated with selective logging (e.g., logging strategy, stand age, and cover of shrub and moss layers) were the most important variables explaining beetle assemblage structure. Our results conclude that selective logging has no significant impacts on overall richness and abundance of ground‐dwelling beetles. However, the negative effects of selective logging on saproxylic species group and some unlogged forest specialists highlight the need for large intact forested areas for sustaining the existence of forest specialist beetles.     

Coexistence through spatio-temporal heterogeneity and species sorting in grassland plant communities

The effect of spatial heterogeneity on species coexistence relies on the degree of niche heterogeneity in the habitat and the ability of species to exploit the available niche opportunities. We studied species coexistence in a perennial grassland, and tested whether small-scale disturbances create environmental heterogeneity that affects coexistence and whether the functional diversity of species in the species pool affects the ability of community composition to reflect heterogeneity through species sorting. We manipulated the spatio-temporal heterogeneity of disturbance and the functional diversity of species added as seed and measured their impact on the spatial turnover of species composition. Disturbance increased environmental heterogeneity and spatial turnover, and the effect of heterogeneity on turnover was greatest in the presence of a functionally diverse species pool, showing the importance of trait variation among species for exploiting environmental heterogeneity, and suggesting that coexistence occurred due to species sorting among heterogeneous niches.     

Aboveground biomass accumulation and tree size distribution in seasonal Atlantic Forest restoration sites

Tropical forests undergoing restoration can present high biomass accumulation rates, especially in the first 20 years. However, native species reforestations often present a bias toward fast growth, low wood density, and small maximum adult size species, contrasting with most mature forest species. Since tree species adult size and wood density are key traits that influence biomass accumulation, these induce uncertainty regarding carbon uptake capabilities of restoration projects in the long term. We compared the density of individuals (DI), basal area (BA), aboveground biomass (AGB), and weighted average wood density (WDW) in 13–14-year-old restoration sites and in mature seasonal Atlantic Forest fragments. We also assessed the contribution of pioneer and non-pioneer and planted and non-planted species on these variables at restoration sites. Furthermore, we investigated the DI and WDW for saplings and seedlings, in order to foresee changes in forest structure that may result from natural recruitment of dense-wood mature species. The BA and WDW at restoration sites were similar to forest fragments, except for large trees (DBH ≥50 cm). Restoration sites recovered AGB to the level of forest fragments only for the smaller size class (DBH 5–19.9 cm). Planted pioneer and non-pioneer species accumulated the greatest AGB (93%), BA (94%), and DI (90%) at restoration sites. The DI of non-planted non-pioneer species with higher WDW increased among saplings and seedlings at restoration sites. The presence of species with a larger adult size and higher WD may indicate long-term increase in biomass accumulation at restoration sites.     

Long‐term changes in the impacts of global warming on leaf phenology of four temperate tree species

Contrary to the generally advanced spring leaf unfolding under global warming, the effects of the climate warming on autumn leaf senescence are highly variable with advanced, delayed, and unchanged patterns being all reported. Using one million records of leaf phenology from four dominant temperate species in Europe, we investigated the temperature sensitivities of spring leaf unfolding and autumn leaf senescence (S_T, advanced or delayed days per degree Celsius). The S_T of spring phenology in all of the four examined species showed an increase and decrease during 1951–1980 and 1981–2013, respectively. The decrease in the S_T during 1981–2013 appears to be caused by reduced accumulation of chilling units. As with spring phenology, the S_T of leaf senescence of early successional and exotic species started to decline since 1980. In contrast, for late successional species, the S_T of autumn senescence showed an increase for the entire study period from 1951 to 2013. Moreover, the impacts of rising temperature associated with global warming on spring leaf unfolding were stronger than those on autumn leaf senescence. The timing of leaf senescence was positively correlated with the timing of leaf unfolding during 1951–1980. However, as climate warming continued, the differences in the responses between spring and autumn phenology gradually increased, so that the correlation was no more significant during 1981–2013. Our results further suggest that since 2000, due to the decreased temperature sensitivity of leaf unfolding the length of the growing season has not increased any more. These finding needs to be addressed in vegetation models used for assessing the effects of climate change.     

Effects of forest successional status on microenvironmental conditions,diversity, and distribution of filmy fern species in a temperate rainforest

The vertical distribution of Hymenophyllaceae species has been related to microenvironmental variations around host trees. We addressed the questions: Do the vertical microenvironmental conditions within forest stands of differing successional statuses vary significantly? Does the diversity of Hymenophyllaceae species differ between forest successional statuses? Are the vertical distribution and diversity of Hymenophyllaceae species related more to humidity or light availability? Are there any interspecific differences in the desiccation tolerance of these species which can be related to their vertical distribution? We characterized the microhabitat conditions (vapor pressure deficit [VPD], air relative humidity [RH], and light availability [PAR]) and the vertical distribution of Hymenophyllaceae species in host trees, in both a secondary forest and an old‐growth temperate rainforest in Chile. Chlorophyll fluorescence was used to monitor the integrity of the photosynthetic apparatus during desiccation experiments. The stand basal area, tree height, and leaf area index were all significantly greater in the old‐growth forest stands, but VPD, RH, and PAR showed no significant differences between the two forests. Both successional statuses showed the same amount of filmy fern species in terms of both abundance and diversity. In both successional statuses VPD and RH decreased while PAR increased with the height of the hosts. Regardless of the forest's age, abundance and diversity of filmy ferns were greater in microsites of greater humidity and less light availability. Desiccation tolerance differed significantly among Hymenophyllaceae species. The distribution pattern could be better explained by the specific microenvironmental requirements and desiccation tolerance rather than the forest's successional status.     

川西亚高山暗针叶林恢复过程中不同恢复阶段的定量分析

以空间代替时间的方法,运用种间联结测定、主成分分析和最优分割法对川西亚高山箭竹-暗针叶林和藓类-暗针叶林经采伐后自然恢复形成的不同恢复系列(20、30、40和50年),以及未被采伐而保留下来的160~200年生暗针叶老龄林进行恢复阶段的定量分析.结果表明:藓类和箭竹暗针叶次生林向暗针叶老龄林恢复过程中,红桦、卧龙柳、五角槭、疏花槭、康定野樱桃、挂苦绣球、椴树和川滇柳归并为衰退种组;湖北花楸、陕甘花楸和微毛野樱桃归并为过渡种组;岷江冷杉、紫果云杉、铁杉和青扦归并为进展种组.20~40年生的次生林进入以红桦为主的阔叶林阶段,其森林类型分别为藓类-红桦林和箭竹-红桦林;恢复到50年,则开始进入红桦和岷江冷杉组成的针阔混交林阶段,其森林类型分别为藓类-红桦-岷江冷杉林和箭竹-红桦-岷江冷杉林;未被采伐而保留下来的160~200年生暗针叶林是以岷江冷杉为主的暗针叶老龄林阶段,其森林类型分别为藓类-岷江冷杉林和箭竹-岷江冷杉林.     

岷江冷杉林皆伐后次生群落结构和物种多样性的演替动态

为阐明岷江冷杉林皆伐后次生群落的演替过程,采用空间代替时间的方法,在川西米亚罗林区海拔3100—3600 m的阴坡选择岷江冷杉林皆伐后次生演替10、20、30、40和50a阶段的次生群落作为研究对象,对其群落结构和物种多样性的动态进行了研究。不同演替阶段的树木均呈显著聚集分布。按群落中优势种的重要值将该演替序列划分为3个类型:悬钩子-蔷薇灌丛、白桦阔叶林和桦木-岷江冷杉针阔混交林。随次生演替,乔木和灌木种的物种丰富度趋于增加,而草本种的物种丰富度趋于减少;乔木和灌木种的Shannon-Wiener多样性指数趋于增大,而草本的Shannon-Wiener多样性指数趋于减小;乔木、灌木和草本层的Pielou均匀度指数均趋于增大;乔木层的Simpson优势度指数趋于减小,灌木和草本层的Simpson优势度指数在演替0—40年阶段趋于增大,而在演替50a阶段趋于减小。在该演替序列中,乔木、灌木和草本层的物种组成均呈耐荫种替代非耐荫种的趋势。     

Multiscale drivers of restoration outcomes for an imperiled songbird

Habitat restoration is a cornerstone of conservation, particularly for habitat‐limited species. However, restoration efforts are seldom rigorously monitored at meaningful spatial scales. Poor understanding of how species respond to habitat restoration programs limits conservation efficacy for habitat‐restricted species like the Golden‐winged Warbler (Vermivora chrysoptera, GWWA). We provide one of the first concerted assessments of a national conservation program aimed at restoring songbird habitat across its breeding range. We studied GWWA response to forest habitat restoration across two broad regions with opposing population trajectories and assessed factors driving species use of restored habitats across multiple spatial scales. From 2015 to 2017, we conducted 1,145 (n = 457 locations) and 519 point counts (n = 215 locations) across the Appalachian Mountains and Great Lakes (respectively) within restored habitats. Warbler abundance within restored habitats across the Great Lakes varied with latitude, longitude, elevation, forest type, and number of growing seasons. In the Appalachian Mountains, occupancy () varied with longitude, elevation, forest type, and number of growing seasons. Detections were restricted to areas within close proximity to population centers (usually <24 km) in the Appalachian Mountains, where GWWAs are rare ( = 0.22, 95% confidence interval [CI]: 0.20–0.25), but not in the Great Lakes, where GWWAs remain common ( = 0.87, 95% CI: 0.84–0.90). Our study suggests that, even when best management practices are carefully implemented, restoration outcomes vary within/across regions and with multiscale habitat attributes. Although assessments of concerted habitat restoration efforts remain uncommon, our study demonstrates the value of monitoring data in the adaptive management process for imperiled species.     

Gap formation and dynamics after long‐term steady state in an old‐growth Picea abies stand in Norway: Above‐ and belowground interactions

Stand dynamics and the gap initiation prior to gap formation are not well‐understood because of its long‐term nature and the scarcity of late‐successional stands. Reconstruction of such disturbance is normally based on historical records and dendroecological methods. We investigated gap initiation and formation at the fine‐scale stand level in the old‐growth reserve of Karlshaugen in Norway. Given its long‐term conservation history, and thorough mapping in permanent marked plots with spatially referenced trees, it provides an opportunity to present stand development before, during, and after gap formation. Late‐successional decline in biomass was recorded after more than 50 years of close to steady state. Gaps in the canopy were mainly created by large old trees that had been killed by spruce bark beetles. Snapping by wind was the main reason for treefall. Long‐term dominance of Norway spruce excluded downy birch and Scots pine from the stand. Comparisons of the forest floor soil properties between the gap and nongap area showed significantly higher concentrations of plant available Ca within the gap area. Plant root simulator (PRS?) probes showed significantly higher supply rates for Ca and Mg, but significantly lower K for the gap compared to the nongap area. Soil water from the gap area had significantly higher C:N ratios compared to the nongap area. Fine‐scale variation with increasing distance to logs indicated that CWD is important for leaking of DOC and Ca. Our long‐term study from Karlshaugen documents gap dynamics after more than 50 years of steady state and a multiscale disturbance regime in an old‐growth forest. The observed disturbance dynamic caused higher aboveground and belowground heterogeneity in plots, coarse woody debris, and nutrients. Our study of the nutrient levels of the forest floor suggest that natural gaps of old‐growth forest provide a long‐lasting biogeochemical feedback system particularly with respect to Ca and probably also N. Norway spruce trees near the gap edge responded with high plasticity to reduced competition, showing the importance of the edge zone as hot spots for establishing heterogeneity, but also the potential for carbon sequestration in old‐growth forest.     

Transient facilitation of resprouting shrubs in fire-prone habitats

Aims Fires play a crucial role mediating species interactions in the Mediterranean Basin, with one prominent example being the nursing effect of post-fire resprouting shrubs on tree recruits, which then outcompete their benefactors throughout succession. Yet, the community structuring role of resprouting shrubs as potential facilitators of post-fire recruiting subshrub species, which are commonly outcompeted in late post-fire stages, has been overlooked. The aims of this work were to investigate (i) whether proximity to resprouting shrubs increased the demographic performance of a fire-adapted carnivorous subshrub and (ii) whether mature shrubs negatively affected the performance of established plants through interference with prey capture.Methods To evaluate the facilitative effects of resprouting shrubs, we sowed seeds of Drosophyllum lusitanicum, a carnivorous, seeder pyrophyte, into two microhabitats in recently burned heathland patches defined by proximity to resprouting shrubs. We monitored key demographic rates of emerged seedlings for 2 years. To test for competitive effects of shrubs on plant performance at a later habitat regeneration stage, we placed greenhouse-reared, potted plants into distinct microhabitats in neighboring burned and unburned heathland patches and monitored prey capture. Both experiments were performed in the Aljibe Mountains at the Northern Strait of Gibraltar and were replicated in 2 years.Important findings Resprouting shrubs significantly improved survival, juvenile size and flowering probability compared with open microhabitats, and had no significantly negative effects on the growth of recruits. Prey capture was significantly lower in unburned heathland patches compared with burned ones, thus partly explaining the decrease in survival of Drosophyllum individuals in mature heathlands. However, microhabitat did not affect prey capture. Our findings suggest that not only periodic fires, removing biomass in mature stands, but also resprouting neighbors, increasing establishment success after fire, may be important for the viability of early successional pyrophytes.     

Structure,dynamics and dendroecology of an old‐growth Fagus forest in the Apennines

Abstract. Question: Which are the structural attributes and the history of old‐growth Fagus forest in Mediterranean montane environments? What are the processes underlying their structural organization? Are these forests stable in time and how does spatial scale affect our assessment of stability? How do these forests compare to other temperate deciduous old‐growth forests? Location: 1600–1850 m a.s.l., Fagus forest near the tree line, central Apennines, Italy. Methods: An old‐growth Fagus forest was studied following historical, structural and dendroecological approaches. History of forest cover changes was analysed using aerial photographs taken in 1945, 1954, 1985 and 1994. The structural analysis was carried out in the primary old‐growth portion of the forest using 18 circular and two rectangular plots. Dendroecological analyses were conducted on 32 dominant or co‐dominant trees. Results: These primary old‐growth Fagus remnants consist of four patches that escaped logging after World War II. Both living and dead tree components are within the range of structural attributes recognized for old‐growth in temperate biomes. Dendroecological analyses revealed the roles of disturbance, competition and climate in structuring the forest. We also identified a persistent Fagus community in which gap‐phase regeneration has led to a mono‐specific multi‐aged stand at spatial scales of a few hectares, characterized by a rotated‐sigmoid diameter distribution. Conclusion: Even at the relatively small spatial scale of this study, high‐elevation Apennine Fagus forests can maintain structural characteristics consistent with those of old‐growth temperate forests. These results are important for managing old‐growth forests in the Mediterranean montane biome.