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Forest Communities (forest + community)

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Humanities and Social Sciences	5%

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Ecology & Organismal Biology	78%
Evolution	9%
4 Other Subdomains	13%

Selected Abstracts

Seedling regeneration, environment and management in a semi-deciduous African tropical rain forest

JOURNAL OF VEGETATION SCIENCE, Issue 5 2009
Edward N. Mwavu
Abstract Questions: How is seedling regeneration of woody species of semi-deciduous rain forests affected by (a) historical management for combinations of logging, arboricide treatment or no treatment, (b) forest community type and (c) environmental gradients of topography, light and soil nutrients? Location: Budongo Forest Reserve, Uganda. Methods: Seedling regeneration patterns of trees and shrubs in relation to environmental factors and historical management types were studied using 32 0.5-ha plots laid out in transects along a topographic gradient. We compared seedling species diversity, composition and distribution patterns along topographic gradients and within types of historical management regimes and forest communities to test whether environmental factors contributed to differences in species composition of seedlings. Results: A total of 85 624 woody seedlings representing 237 species and 46 families were recorded in this rain forest. Cynometra alexandri C.H. Wright and Lasiodiscus mildbraedii Engl. had high seedling densities and were widely distributed throughout the plots. The most species-rich families were Euphorbiaceae, Fabaceae, Rubiaceae, Meliaceae, Moraceae and Rutaceae. Only total seedling density was significantly different between sites with different historical management, with densities highest in logged, intermediate in logged/arboricided and lowest in the nature reserve. Forest communities differed significantly in terms of seedling diversity and density. Seedling composition differed significantly between transects and forest communities, but not between topographic positions or historical management types. Both Chao-Jaccard and Chao-Sørensen abundance-based similarity estimators were relatively high in the plot, forest community and in terms of historical management levels, corroborating the lack of significant differences in species richness within these groups. The measured environmental variables explained 59.4% of variance in seedling species distributions, with the three most important being soil organic matter, total soil titanium and leaf area index (LAI). Total seedling density was positively correlated with LAI. Differences in diversity of >2.0 cm dbh plants (juveniles and adults) also explained variations in seedling species diversity. Conclusions: The seedling bank is the major route for regeneration in this semi-deciduous tropical rain forest, with the wide distribution of many species suggesting that these species regenerate continuously. Seedling diversity, density and distribution are largely a function of adult diversity, historical management type and environmental gradients in factors such as soil nutrient content and LAI. The species richness of seedlings was higher in soils both rich in titanium and with low exchangeable cations, as well as in logged areas that were more open and had a low LAI. [source]

Land use legacies in post-agricultural forests in the Doupovské Mountains, Czech Republic

APPLIED VEGETATION SCIENCE, Issue 2 2009
Martin Kopecký
Abstract Questions: Do differences in previous land use cause long-lasting changes in soil chemistry? Is vegetation composition affected by the previous land use after 50 years of secondary succession? Is the effect of previous land use caused by pre-existing differences in environmental conditions or mediated through changes in soil chemistry? How important is the effect of previous land use in relation to other factors? Location: Doupovské Mountains, Czech Republic. Methods: A stratified random sampling design was used to collect 91 vegetation relevés with accompanying soil samples. The effects of previous land use (arable field, meadow, pasture) on soil pH, organic carbon (C), total nitrogen (N), C:N ratio and available phosphorus were tested by an analysis of covariance. A canonical correspondence analysis and variation partitioning procedure were used to reveal relationships among previous land use, environmental factors and species composition. Results: Organic C, total N and C:N ratio were significantly influenced by previous land use, while available phosphorus and soil pH were not. Previous land use explained a significant part of the variation in species composition and its effects only partly overlapped with the effects of soil chemistry and terrain attributes. However, the species composition of post-agricultural forests was mostly determined by environmental factors not modified by previous land use. Conclusions: Forest communities that originate on abandoned agricultural land are primarily determined by natural environmental conditions. Nevertheless, the type of previous land use also modifies the species assemblages of these forests and needs to be considered as an important determinant of their composition. [source]

Ecology and conservation status of temporary and fluctuating ponds in two areas of southern England

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2009
D.T. Bilton
Abstract 1.A high proportion of ponds are temporary in nature, although the biodiversity value of such sites is still poorly recognized. This work explores the plant and macroinvertebrate communities of 76 temporary and fluctuating water bodies in two regions of southern England (Lizard Peninsula, Cornwall and New Forest, Hampshire) that have retained high pond densities. The ecology and conservation status of sites is examined, and comparisons made with ponds elsewhere in England and Wales. 2.Lizard and New Forest ponds supported 119 plant and 165 macroinvertebrate species respectively. Patterns of community similarity for plants and macroinvertebrates were highly concordant, taxa being related in a similar manner to measured environmental variables including pond area, depth, pH and water chemistry. 3.Patterns of pond occupancy revealed that most species were locally rare, over half occurring in less than 10% of ponds, and less than 10% being recorded from more than 50% of sites. More than 50% of ponds supported at least one nationally rare plant and almost 75% at least one nationally rare macroinvertebrate. These taxa occupied a wide range of pond types in each region, and did not have predictably different ecologies from common species. 4.Comparisons with ponds elsewhere in England and Wales revealed that Lizard and New Forest communities are nationally distinct, being most similar to ponds in areas of low intensity agriculture elsewhere in western Britain. Individual ponds in both regions supported more nationally rare taxa, on average, than ponds sampled in the national survey. 5.Ponds in the two areas have high conservation value, both regionally and nationally, supporting almost 75% of the global species richness of temporary ponds sampled across England and Wales. Within each region, many taxa are found in relatively few sites, and effective conservation of pond biodiversity will require a regional management approach. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Atlantic Forest Butterflies: Indicators for Landscape Conservation,

BIOTROPICA, Issue 4b 2000
Keith S. Brown Jr.
ABSTRACT The Atlantic Forest region (wide sense) includes very complex tropical environments, increasingly threatened by extensive anthropogenic conversion (>90%). Ecologically specialized, short-generation insects (butterflies) are evaluated here as indicators for monitoring community richness, landscape integrity, and sustainable resource use in the region. The > 2100 butterfly species in the Atlantic Forest tegion have been censused in many sites over 35 years, giving comparable daily, weekly, monthly, and long-tetm site lists. The 21 most thoroughly studied sites include 218,914 species, of which half can be censused in a week or less. The butterfly communities are divided into six relatively distinct faunal regions, centered in the northeast, the central coastal tablelands, the southeast coastal plain, the mountains plus interior of the southeastern states, the central plateau, and the southern states. Species richness shows the highest values in coastal mountains from 15 to 23°S. Local butterfly communities show a high turnover, with 20 to 40 percent of the species, especially small Lycaenidae and Hesperiidae, recorded only as unstable populations or "tourists." Easily sampled species in the family Nymphalidae, and especially its bait-attracted subfamilies, are best correlated with the entire butterfly fauna and can be used as surrogates for species diversity. In most butterfly groups, species richness is well predicted by landscape connectivity alone, or by composite indices of environmental heterogeneity, natural disturbance, and (negatively) anthropogenic disturbance. Principal components and redundancy analyses showed that the richness and proportions of different butterfly groups in the local fauna are variably explained by disturbance, seasonality, temperature, vegetation, soils, and landscape connectivity. Various groups thus can be used as rapid indicators of different types of change in the community, its environment, and the landscape. Threatened and rare species also can be used as indicators of the most unique Atlantic Forest communities (paleoenvironments), which need special attention. RESUMO A região da Mata Atlantica latu senstt inclui ambientes tropicals muito complexes, cada vez mais amea¸ados por extensa conversão antrópica (>90%). Insetos pequenos, especializados, e de ciclo rápido (borboletas) são avaliados neste trabalho como indicadores para o monitoramento da tiqueza de comunidades, integridade de paisagens, e uso susten-tável de recursos na região. As >2100 espécies de borboletas na região da Mata Atlantica têrn sido recenseadas em muitos sítios durante os últimos 35 anos, dando listas comparáveis diárias, semanais, mensais e totais para cada sítio. Os 21 sítios mais intensivamente estudados incluem 218,914 espécies, das quais metade pode ser amostrada em uma semana ou menos. As comunidades de borboletas são divididas em seis subregiões faunísticas relativamente distintas, centradas no nordeste, nos tabuleiros baianos, no literal do sudeste, nas regiões montanhosas no interior dos estados do sudeste, no Planalto Central, e no estados do sul. A riqueza de espécies é maior nas serras costeiras entre 15 c 23°S. As comunidades locals de borboletas possuem alta reposi¸ão, com 20 a 40 por cento das espécies, especialmente os pequenos Lycaenidae e Hesperiidae, registradas em popula¸ões instáveis ou sendo apenas "turistas." As espécies facilmente amostradas na família Nymphalidae, especialmente as atraídas a iscas fermentadas, são mais correlacionadas com a riqueza total e podem ser usadas como estimadores da riqueza total no ambiente. Na maior parte dos grupos de borboletas, a riqueza de espécies é altamente correlacionada com conectividade simples da paisagem, e com índices compostos de heterogeneidade, perturba¸ão natural, e (negativamente) perturba¸ão total no ambiente. As análises de Componentes Principals e de Redundãncia mostram que as riquezas e proor¸ões de diferentes grupos de borboletas são variavelmente explicadas por pertba¸ão, sazonalidade, temperatura, vegeta¸ão, solos, e conectividade. Váries grupos podem assim ser úteis como indicadores rápidos de diferentes tipos de mudan¸as na comunidade, no seu ambiente, e na paisagem. Espécies raras e amea¸adas podem também ser usadas para indicar os sistemas mais únicos na região (paleoarnbientes), que necessitam de aten¸ão especial. [source]

The Northwest Forest Plan as a Model for Broad-Scale Ecosystem Management: a Social Perspective

CONSERVATION BIOLOGY, Issue 2 2006
SUSAN CHARNLEY
conservación y desarrollo; comunidades rurales; gestión forestal; monitoreo socioeconómico Abstract:,I evaluated the Northwest Forest Plan as a model for ecosystem management to achieve social and economic goals in communities located around federal forests in the U.S. Pacific Northwest. My assessment is based on the results of socioeconomic monitoring conducted to evaluate progress in achieving the plan's goals during its first 10 years. The assessment criteria I used related to economic development and social justice. The Northwest Forest Plan incorporated economic development and social justice goals in its design. Socioeconomic monitoring results indicate that plan implementation to achieve those goals met with mixed success, however. I hypothesize there are two important reasons the plan's socioeconomic goals were not fully met: some of the key assumptions underlying the implementation strategies were flawed and agency institutional capacity to achieve the goals was limited. To improve broad-scale ecosystem management in the future, decision makers should ensure that natural-resource management policies are socially acceptable; land-management agencies have the institutional capacity to achieve their management goals; and social and economic management goals (and the strategies for implementing them) are based on accurate assumptions about the relations between the resources being managed and well-being in local communities. One of the difficulties of incorporating economic development and social justice goals in conservation initiatives is finding ways to link conservation behavior and development activities. From a social perspective, the Northwest Forest Plan as a model for ecosystem management is perhaps most valuable in its attempt to link the biophysical and socioeconomic goals of forest management by creating high-quality jobs for residents of forest communities in forest stewardship and ecosystem management work, thereby contributing to conservation. Resumen:,Evalué el Plan Forestal del Noroeste como un modelo para la gestión de ecosistemas para alcanzar metas sociales y económicas en comunidades localizadas alrededor de bosques federales en el Pacífico Noroeste de E.U.A. Mi evaluación se basa en los resultados del monitoreo socioeconómico desarrollado para evaluar el progreso en el logro de las metas del plan durantes sus 10 primeros años. Los criterios de evaluación que utilicé se relacionan con el desarrollo económico y la justicia social. El diseño del Plan Forestal del Noroeste incorporó metas de desarrollo económico y de justicia social. Sin embargo, los resultados del monitoreo socioeconómico indican que éxito en la implementación del plan para alcanzar esas metas fue combinado. Postulé la hipótesis de que hay dos razones importantes por las que las metas socioeconómicas del plan no se cumplieron totalmente: algunas de las suposiciones clave en las estrategias de implementación fueron deficientes y la capacidad institucional de la agencia para alcanzar las metas era limitada. Para mejorar la gestión de ecosistemas a gran escala en el futuro, los tomadores de decisiones deberán asegurarse que las políticas de gestión de recursos naturales sean aceptables socialmente; que las agencias de gestión de tierras tengan la capacidad institucional para cumplir sus metas de gestión; y que las metas de gestión sociales y económicas (y las estrategias para su implementación) se basen en suposiciones precisas de las relaciones entre los recursos a gestionar y el bienestar de las comunidades locales. La manera de vincular comportamiento de conservación y actividades de desarrollo es una de las dificultades para la incorporación de metas de desarrollo económico y de justicia social en las iniciativas de conservación. Desde una perspectiva social, el Plan Forestal del Noroeste como modelo para la gestión de ecosistemas quizás es más valioso por su intento de vincular las metas biofísicas y socioeconómicas de la gestión forestal mediante la creación de empleos de alta calidad para residentes de las comunidades en labores de regulación y supervisión forestal y de gestión de ecosistemas, por lo tanto contribuye a la conservación. [source]

The role of floristic survey data and quantitative analysis in identification and description of ecological communities under threatened species legislation: A case study from north-eastern New South Wales

ECOLOGICAL MANAGEMENT & RESTORATION, Issue 2009
Penny Kendall
Summary The concept of ecological communities play an important role in conservation planning and natural resource management. However, inherent uncertainties in the definition and identification of individual communities make it difficult to assess whether particular communities are present on particular sites and how they may be affected by proposed developments or management actions. If communities are poorly defined or misidentified, they may not perform their intended role as effective representations of biodiversity. We use a case study of forest communities dominated by Brown Barrel (Eucalyptus fastigata) in north-eastern New South Wales to demonstrate the value of quantitative floristic survey data for resolving robust and effective classifications of communities. Numerical analyses of an extensive set of floristic data suggested a re-configuration of a prior classification based largely on subjective interpretation. Although the general existence of assemblages dominated by Brown Barrel was confirmed, the new classification replaced three prior units with two assemblages that were more robust and better reflected the overall patterns in species composition. As only one of the two assemblages potentially warranted threatened status, the new classification allows scarce conservation resources to be targeted where they are most needed. The quantitative survey data also enabled a more detailed floristic description of the assemblages and provided a basis for maps of point locations and modelled habitat. These maps identified previously undocumented occurrences of the communities and helped to assess their extent of decline since European settlement. Improving the coverage of quadrat-based floristic sampling is therefore a valuable and cost-effective investment to inform better management of native vegetation and biodiversity. [source]

Positive diversity,stability relationships in forest herb populations during four decades of community assembly

ECOLOGY LETTERS, Issue 10 2010
Martin Dov
Ecology Letters (2010) Abstract It is suggested that diversity destabilizes individual populations within communities; however, generalizations are problematic because effects of diversity can be confounded by variation attributable to community type, life history or successional stage. We examined these complexities using a 40-year record of reassembly in forest herb communities in two clearcut watersheds in the Andrews Long-term Ecological Research Site (Oregon, USA). Population stability was higher among forest than colonizing species and increased with successional stage. Thus, life history and successional stage may explain some of the variability in diversity,stability relationships found previously. However, population stability was positively related to diversity and this relationship held for different forest communities, for species with contrasting life histories, and for different successional stages. Positive relationships between diversity and population stability can arise if diversity has facilitative effects, or if stability is a precursor, rather than a response, to diversity. [source]

Species-specific responses to atmospheric carbon dioxide and tropospheric ozone mediate changes in soil carbon

ECOLOGY LETTERS, Issue 11 2009
Alan F. Talhelm
Abstract We repeatedly sampled the surface mineral soil (0,20 cm depth) in three northern temperate forest communities over an 11-year experimental fumigation to understand the effects of elevated carbon dioxide (CO2) and/or elevated phyto-toxic ozone (O3) on soil carbon (C). After 11 years, there was no significant main effect of CO2 or O3 on soil C. However, within the community containing only aspen (Populus tremuloides Michx.), elevated CO2 caused a significant decrease in soil C content. Together with the observations of increased litter inputs, this result strongly suggests accelerated decomposition under elevated CO2. In addition, an initial reduction in the formation of new (fumigation-derived) soil C by O3 under elevated CO2 proved to be only a temporary effect, mirroring trends in fine root biomass. Our results contradict predictions of increased soil C under elevated CO2 and decreased soil C under elevated O3 and should be considered in models simulating the effects of Earth's altered atmosphere. [source]

Interspecific relationships among growth, mortality and xylem traits of woody species from New Zealand

FUNCTIONAL ECOLOGY, Issue 2 2010
Sabrina E. Russo
Summary 1.,Wood density is considered a key functional trait influencing the growth and survival of woody plants and has been shown to be related to a slow,fast rate-of-living continuum. Wood density is, however, an emergent trait arising from several vascular properties of wood, including the diameter and frequency of xylem conduits. 2.,We aimed to test the hypotheses that there is a set of inter-related trade-offs linked to the different functions of wood, that these trade-offs have direct consequences for tree growth and survival and that these trade-offs underlie the observed correlations between wood density and demographic rates. We evaluated the covariation between xylem anatomical traits among woody species of New Zealand and whether that covariation had the potential to constrain variation in wood density and demographic rates. 3.,Several xylem traits were strongly correlated with each other, but wood density was not correlated with any of them. We also found no significant relationships between wood density and growth or mortality rate. Instead, growth was strongly related to xylem traits associated with hydraulic capacity (conduit diameter and a conductivity index) and to maximum height, whereas mortality rate was strongly correlated only with maximum height. The diameter and frequency of conduits exhibited a significant negative relationship, suggesting a trade-off, which restricted variation in wood density and growth rate, but not mortality rate. 4.,Our results suggest, for woody species in New Zealand, that growth rate is more closely linked to xylem traits determining hydraulic conductance, rather than wood density. We also found no evidence that denser woods conferred higher survival, or that risk of cavitation caused by wide conduits increased mortality. 5.,In summary, we found little support for the idea that wood density is a good proxy for position along a fast,slow rate-of-living continuum. Instead, the strong, negative relationship between vessel diameter and frequency may constrain the realized diversity of demographic niches of tree species in New Zealand. Trade-offs in function therefore have the potential to shape functional diversity and ecology of forest communities by linking selection on structure and function to population-level dynamics. [source]

Stem hydraulics mediates leaf water status, carbon gain, nutrient use efficiencies and plant growth rates across dipterocarp species

FUNCTIONAL ECOLOGY, Issue 4 2009
Jiao-Lin Zhang
Summary 1Stem vascular system strongly influences structure and functioning of leaves, life-history, and distribution of plants. Xylem structure and hydraulic conductivity of branches, leaf functional traits, and growth rates in 17 dipterocarp species in a mature plantation stand were examined to explore the functional relationships between these traits. 2Maximum hydraulic conductivity on the bases of both sapwood and leaf area (kL) were positively correlated with midday leaf water potential in the rainy season, stomatal conductance, area-based maximum photosynthetic rate, photosynthetic N (PNUE) and P use efficiencies (PPUE), and mean height and diameter growth rates. Moreover, kL was positively correlated with mesophyll thickness and mass-based maximum photosynthetic rate. These results revealed the mechanistic linkage between stem hydraulics and leaf photosynthesis through nutrient use efficiency and mesophyll development of leaves. 3A detrended correspondence analysis (DCA) using 37 traits showed that the traits related to stem hydraulics and leaf carbon gain were loaded on the first axis whereas traits related to light harvesting were loaded on the second axis, indicating that light harvesting is a distinct ecological axis for tropical canopy plants. The DCA also revealed a trade-off between photosynthetic water use efficiency and hydraulic conductivity along with PNUE and PPUE. 4The congeneric species were scattered fairly close together on the DCA diagram, indicating that the linkages between stem hydraulics, leaf functional traits, and plant growth rates are phylogenetically conserved. 5These results suggest that stem hydraulics mediates leaf water status, carbon gain, nutrient use efficiencies, and growth rates across the dipterocarp species. The wide variation in functional traits and growth rates among these dipterocarp species along with the trade-offs mentioned above provide a possible explanation for their co-existence in tropical forest communities. [source]

The Deciduous Forest , Boreal Forest Ecotone

GEOGRAPHY COMPASS (ELECTRONIC), Issue 7 2010
David Goldblum
Ecotones have been subject to significant attention over the past 25 years as a consensus emerged that they might be uniquely sensitive to the effects of climate change. Most ecotone field studies and modeling efforts have focused on transitions between forest and non-forest biomes (e.g. boreal forest to Arctic tundra, forest to prairie, subalpine forests to alpine tundra) while little effort has been made to evaluate or simply understand forest,forest ecotones, specifically the deciduous forest , boreal forest ecotone. Geographical shifts and changes at this ecotone because of anthropogenic factors are tied to the broader survival of both the boreal and deciduous forest communities as well as global factors such as biodiversity loss and dynamics of the carbon cycle. This review summarizes what is known about the location, controlling mechanisms, disturbance regimes, anthropogenic impacts, and sensitivity to climate change of the deciduous forest , boreal forest ecotone. [source]

Why does the unimodal species richness,productivity relationship not apply to woody species: a lack of clonality or a legacy of tropical evolutionary history?

GLOBAL ECOLOGY, Issue 3 2008
Lauri Laanisto
ABSTRACT Aim, To study how differences in species richness patterns of woody and herbaceous plants may be influenced by ecological and evolutionary factors. Unimodal species richness,productivity relationships (SRPRs) have been of interest to ecologists since they were first described three decades ago for British herbaceous vegetation by J. P. Grime. The decrease in richness at high productivity may be due to competitive exclusion of subordinate species, or diverse factors related to evolution and dispersal. Unimodal SRPRs are most often reported for plants, but there are exceptions. For example, unimodal SRPRs are common in the temperate zone but not in the tropics. Similarly, woody species and forest communities in the Northern Hemisphere do not tend to show unimodal SRPRs. Location, Global. Methods, We used data from the literature to test whether a unimodal SRPR applies to woody species and forest communities on a global scale. We explored whether the shape of SRPRs may be related to the lack of clonality in woody species (which may prevent their being competitively superior), or the legacy of evolutionary history (most temperate woody species originate from tropical lineages, and due to niche conservatism they may still demonstrate ,tropical patterns'). We used case studies that reported the names of the dominant or most abundant species for productive sites. Results, Woody species were indeed less clonal than herbaceous species. Both clonality and the temperate evolutionary background of dominating species were associated with unimodality in SRPRs, with woodiness modifying the clonality effect. Main conclusions, The unimodal SRPR has been common in the ecological literature because most such studies originate from temperate herbaceous communities with many clonal species. Consequently, both evolutionary and ecological factors may influence species richness patterns. [source]

Reciprocal distribution of two congeneric trees, Betula platyphylla var. japonica and Betula maximowicziana, in a landscape dominated by anthropogenic disturbances in northeastern Japan

JOURNAL OF BIOGEOGRAPHY, Issue 12 2005
Katsuhiro Osumi
Abstract Aim, Information has been compiled on disturbance regimes and the life-history characteristics of Betula platyphylla var. japonica (Miq.) Hara and B. maximowicziana Regel to investigate the impact of humans on the present distribution patterns of these two congeneric tree species. Location, The study area is in the central region of the northern Kitakami Mountain Range, located in the northeast of Honshu Island, Japan. Methods, First, the present distributions of B. maximowicziana and B. platyphylla var. japonica were mapped at the landscape scale. To examine the factors affecting the distribution patterns, topographic features and past land use were taken into account. Second, life-history traits of both species were clarified at various growth stages either by fieldwork or through a literature search. Previous studies have provided some information on seed production, seed dispersal, seedling dynamics, sprouting, and growth. In the present study, field observations and experiments were conducted regarding seed-bank formation, size and age at reproduction, and the life span of canopy trees. Results,Betula platyphylla var. japonica and B. maximowicziana were spatially segregated in the studied landscape (14,000 ha). The distribution of each species was correlated more strongly with land use at the beginning of the twentieth century than with site environmental factors such as altitude or slope angle. Betula platyphylla var. japonica was distributed more frequently on former grasslands, whereas B. maximowicziana was almost exclusively limited to past old-growth forests. As typical pioneers, the two species showed similar life-history traits but differed in several critical points. Betula platyphylla var. japonica has a vigorous sprouting ability, which might increase its resistance to burning and logging, whereas B. maximowicziana forms a persistent seed bank in the soil, indicating an advantage in regenerating in disturbances found in forest communities. Other critical differences were detected in age-related characteristics such as minimum age of reproduction and life span. Main conclusions, The earlier reproductive maturity and the shorter life span of B. platyphylla var. japonica indicate a shorter population cycle than that for B. maximowicziana. The latter would be excluded from grasslands that were burned frequently, as a result of the longer time span before initial reproduction and its poor sprouting ability. In contrast, B. platyphylla var. japonica would be excluded from old-growth forests, where disturbance was infrequent, owing to its shorter life span and lack of a persistent seed bank. [source]

Size-dependence of growth and mortality influence the shade tolerance of trees in a lowland temperate rain forest

JOURNAL OF ECOLOGY, Issue 4 2009
Georges Kunstler
Summary 1A trade-off between growth in high-light and survival in low-light of species is often proposed as a key mechanism underpinning the dynamics of trees in forest communities. Yet, growth and survival are known to depend on plant size and few studies have analysed how this trade-off can vary between juvenile life stages and the potential consequences of the trade-off for the differences in regeneration rate between species in mixed forests. 2We quantified growth and mortality for two different juvenile life stages , seedlings and saplings , of seven tree species common in temperate rain forests in New Zealand using data from field studies. We found strong evidence that the ranking of species for survival in shade and growth in full light was affected by size. There was a trade-off between seedling survival in low light and sapling height growth in high light, but no trade-offs were observed when considering other combinations of life stages (seedling growth vs. seedling survival, seedling growth vs. sapling survival, or sapling growth vs. sapling survival). 3We ran simulations with an individual-based forest dynamics model , SORTIE/NZ , to explore how the trade-off drives the differences in tree species regeneration success in gaps vs. under closed forest conditions. These simulations indicate that because species' ranks in shade tolerance varied with life stage, regeneration success was not predicted from knowledge of tree performance at a single life stage. For instance, high-light sapling growth was a strong determinant of regeneration success in forest gaps, but seedling growth was also influential. Under closed forest, regeneration success was primarily limited by low-light mortality at the seedling stage, but seedling growth and sapling survival were also influential. 4Synthesis. Growth-survival trade-offs can be strongly affected by the size of the individual analysed, resulting in completely different rankings of the shade tolerance of species across different juvenile life stages. Performance of both seedlings and saplings influenced regeneration success, highlighting the need to consider growth-survival trade-offs and the shade-tolerance strategies of tree species over a large range of juvenile sizes. [source]

Maximum size distributions in tropical forest communities: relationships with rainfall and disturbance

JOURNAL OF ECOLOGY, Issue 3 2008
Lourens Poorter
Summary 1The diversity and structure of communities are partly determined by how species partition resource gradients. Plant size is an important indicator of species position along the vertical light gradient in the vegetation. 2Here, we compared the size distribution of tree species in 44 Ghanaian tropical forest communities, using data from 880 one-hectare plots and over 118 000 trees belonging to more than 210 species. 3The size distribution of forest species showed a continuous normal or log-normal distribution, with many canopy species and a few large species, and varied from community to community. Multiple regression showed that this variation is related to rainfall and to disturbance. 4Size distributions in wet forests were less skewed than those in dry forests, with a smaller proportion of big species and a smaller size range. At the same time they exhibited tighter species packing, resulting in higher species richness. Communities with high disturbance have less species packing and lower species richness. 5Synthesis. We conclude that the factors that constrain organism size and species coexistence in these tropical forest tree communities differ from those known to operate on a number of well-studied animal communities. [source]

Soil nutrient supply and biomass production in a mixed forest on a skeleton-rich soil and an adjacent beech forest

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2002
Dirk Hölscher
Abstract In the natural forest communities of Central Europe, beech (Fagus sylvatica L.) predominates in the tree layer over a wide range of soil conditions. An exception with respect to the dominance of beech are skeleton-rich soils such as screes where up to 10 broad-leaved trees co-exist. In such a Tilia-Fagus-Fraxinus-Acer-Ulmus forest and an adjacent mono-specific beech forest we compared (1) soil nutrient pools and net nitrogen mineralization rates, (2) leaf nutrient levels, and (3) leaf litter production and stem increment rates in order to evaluate the relationship between soil conditions and tree species composition. In the mixed forest only a small quantity of fine earth was present (35 g l,1) which was distributed in patches between basalt stones; whereas a significantly higher (P < 0.05) soil quantity (182 g l,1) was found in the beech forest. In the soil patches of the mixed forest C and N concentrations and also concentrations of exchangeable nutrients (K, Ca, Mg) were significantly higher than in the beech forest. Net N mineralization rates on soil dry weight basis in the mixed forest exceeded those in the beech forest by a factor of 2.6. Due to differences in fine earth and stone contents, the volume related soil K pool and the N mineralization rate were lower in the mixed forest (52 kg N ha,1 yr,1, 0,10 cm depth) than in the beech forest (105 kg N ha,1 yr,1). The leaf N and K concentrations of the beech trees did not differ significantly between the stands, which suggests that plant nutrition was not impaired. In the mixed forest leaf litter fall (11,%) and the increment rate of stem basal area (52,%) were lower than in the beech forest. Thus, compared with the adjacent beech forest, the mixed forest stand was characterized by a low volume of patchy distributed nutrient-rich soil, a lower volume related K pool and N mineralization rate, and low rates of stem increment. Together with other factors such as water availability these patterns may contribute to an explanation of the diverse tree species composition on Central European screes. Bodennährstoffangebot und Biomasseproduktion in einem Mischwald auf einem stark skeletthaltigen Standort und in einem benachbarten Buchenwald In den natürlichen Waldgesellschaften Mitteleuropas dominiert die Buche (Fagus sylvatica L.) über ein weites Spektrum an bodenchemischen Standortsbedingungen. Eine Ausnahme in Bezug auf die Buchendominaz bilden stark skeletthaltige Standorte, wie etwa Blockhalden, wo bis zu 10 Laubbaumarten gemeinsam vorkommen. In solch einem Tilia-Fagus-Fraxinus-Acer-Ulmus -Wald und einem benachbarten Buchenreinbestand haben wir (1) die Bodennährstoffvorräte und Stickstoffmineralisationsraten, (2) den Blattnährstoffstatus und (3) die Blattproduktion und die Stammzuwachsraten vergleichend untersucht, um die Beziehung zwischen den Bodenbedingungen und der Baumartenzusammensetzung zu charakterisieren. In dem Mischwald fanden wir nur eine geringe Menge an Feinboden (35 g l,1), die sich in Taschen zwischen den Basaltsteinen befand, wohingegen ein signifikant (P < 0.05) höherer Gehalt an Feinboden (182 g l,1) in dem Buchenwald vorhanden war. In den Bodentaschen des Mischwaldes waren die C- und N-Konzentrationen und auch die Konzentrationen an austauschbar gebundenem K, Ca und Mg signifikant höher als im Buchenwald. Die Netto-N-Mineralisation pro Gewichtseinheit im Mischwald überstieg diejenige im Buchenwald um den Faktor 2,6. Wegen der unterschiedlichen Anteile an Feinboden und Skelett waren der volumenbezogene K-Vorrat und die volumenbezogene N-Mineralisationsrate im Mischwald (52 kg N ha,1 yr,1, 0,10 cm Tiefe) geringer als im Buchenwald (105 kg N ha,1 yr,1). Die Blattnährstoffgehalte von Buchen unterschieden sich zwischen den beiden Beständen nicht signifikant, was darauf hinweist, dass die Pflanzenernährung nicht beeinträchtigt war. Der herbstliche Blattstreufall (11,%) und die Zuwachsraten der Stammquerflächen (52,%) waren im Mischwald geringer als im Buchenwald. Im Vergleich mit dem benachbarten Buchenwald wies der Mischwald somit einen geringen Gehalt an sehr ungleichmäßig verteiltem, nährstoffreichen Boden, geringere volumenbezogene K-Vorräte und N-Mineralisationsraten und geringe Stammzuwächse auf. Gemeinsam mit anderen Faktoren, wie etwa der Wasserverfügbarkeit, können diese Muster zu einer Erklärung der Baumartenvielfalt auf mitteleuropäischen Blockstandorten beitragen. [source]

Long-term successional forest dynamics: species and community responses to climatic variability

JOURNAL OF VEGETATION SCIENCE, Issue 4 2010
Paul Kardol
Abstract Question: Are trees sensitive to climatic variability, and do tree species differ in their responses to climatic variability? Does sensitivity of forest communities to climatic variability depend on stand composition? Location: Mixed young forest at Walker Branch Watershed near Oak Ridge, East Tennessee, USA. Methods: Using a long-term dataset (1967,2006), we analyzed temporal forest dynamics at the tree and species level, and community dynamics for forest stands that differed in initial species composition (i.e., chestnut oak, oak,hickory, pine, and yellow poplar stands). Using summer drought and growing season temperature as defined climate drivers, we evaluated relationships between forest dynamics and climate across levels of organization. Results: Over the four-decade study period, forest communities underwent successional change and substantially increased in biomass. Variation in summer drought and growing season temperature contributed to temporal biomass dynamics for some tree species, but not for others. Stand-level responses to climatic variability were related to the responses of component species, except in pine stands. Pinus echinata, the dominant species in pine stands, decreased over time due to periodic outbreaks of pine bark beetle (Dendroctonus frontalis). These outbreaks at Walker Branch could not be directly related to climatic conditions. Conclusions: The results indicate that sensitivity of developing forests to climatic variability is stand type-dependent, and hence is a function of species composition. However, in the long term, direct effects of climatic variability on forest dynamics may be small relative to autogenic successional processes or climate-related insect outbreaks. Empirical studies testing for interactions between forest succession and climatic variability are needed. [source]

Seedling regeneration, environment and management in a semi-deciduous African tropical rain forest

Can the seed bank be used for ecological restoration?

JOURNAL OF VEGETATION SCIENCE, Issue 6 2008
An overview of seed bank characteristics in European communities
Abstract Question: Can seeds in the seed bank be considered as a potential source of material for the restoration of European plant communities including forest, marsh, grassland and heathland? Methods: This study reviews seed bank studies (1990,2006) to determine if they provide useful and reliable results to predict restoration success. We formally selected 102 seed bank studies and analyzed differences between four plant community types in several seed bank characteristics, such as seed density, species richness and similarity between seed bank and vegetation. We also assessed the dominant genera present in the seed bank in each plant community. Results: We observed remarkably consistent trends when comparing seed bank characteristics among community types. Seed density was lowest for grassland and forest communities and highest in marshes, whereas species richness, diversity and evenness of the seed bank community was lowest in heathland and highest in grassland. Similarity between seed bank and vegetation was low in forest, and high in grassland. There was a lot of overlap of the dominant genera of seed bank communities in all studies. Conclusions: The absence of target species and the high dominance of early successional species, in particular Juncus spp., indicate that restoration of target plant communities relying only on seed germination from the seed bank is in most cases not feasible. The exceptions are heathland and early successional plant communities occurring after temporally recurring disturbances. Restoration of plant communities composed of late successional species, such as woody species or herbaceous species typical of woodland or forest rely mainly on seed dispersal and not on in situ germination. [source]

Structure and composition of vegetation along an elevational gradient in Puerto Rico

JOURNAL OF VEGETATION SCIENCE, Issue 5 2006
W.A. Gould
Liogier & Martorrell (1999) Abstract Question: What are the composition, conservation status, and structural and environmental characteristics of eight mature tropical forest plant communities that occur along an elevational gradient. Location: Northeastern Puerto Rico. Methods: We quantified the species composition, diversity, conservation status, and ecological attributes of eight mature tropical forest plant communities in replicated plots located to sample representative components of important forest types occurring along an elevational gradient. A suite of environmental and vegetation characteristics were sampled at each plot and summarized to characterize communities and analyse trends along the elevational gradient. Results: The set of communities included 374 species; 92% were native, 14% endemic, and 4% critical elements (locally endangered) to the island. All communities, occurring within a wide range of patch sizes and degree of conservation protection, showed a high percentage of native species (> 89% per plot). The lowland moist forest communities, occurring within a matrix of urbanization, agriculture, and disturbance, had the highest degree of invasion by exotics. Community descriptions were nested within a variety of hierarchies to facilitate extrapolation of community characteristics to larger ecosystem units. Basal area, above-ground biomass, canopy heights, and mean species richness peaked at mid elevations. Conclusions: It is significant that all of these forest communities continue to be dominated by native species while existing in a matrix of human and natural disturbance, species invasion, and forest regeneration from widespread agriculture. The lowland moist and dry forest types represent a minority of the protected forested areas in Puerto Rico, serve as unique genetic reservoirs, and should be protected. [source]

Plant traits as predictors of woody species dominance in climax forest communities

JOURNAL OF VEGETATION SCIENCE, Issue 3 2001
Fumito Koike
Satake et al. (1989) Abstract. The dominance of a given tree or shrub species in a particular forest community may be determined by many ecological traits of the target species, as well as those of the surrounding species as its potential competitors. The present study was conducted to evaluate the possibility of predicting community status (species composition and dominance) on the basis of traits of local flora using statistical methods, and to visualize the mathematical function which determines species dominance. A general linear model and logistic regression were used for the statistical analysis. Dependent variables were designated as dominance and presence/absence of species in climax forest, with independent variables as vegetative and reproductive traits. Subalpine, cool-temperate, warm-temperate and subtropical climax rain forests in East Asia were studied. Quantitative prediction of climax community status could readily be made based on easily measured traits of local flora. Species composition and 74.6% of the total variance of species dominance were predicted based on two traits; maximum height and shade tolerance. Through application of this method, the capacity of an alien species to invade a climax forest community could possibly be predicted prior to introduction of the alien species. [source]

Fagus sylvatica forest vegetation in Greece: Syntaxonomy and gradient analysis

JOURNAL OF VEGETATION SCIENCE, Issue 1 2001
Erwin Bergmeier
Abstract. This is the first comprehensive study on Fagus sylvatica s.l. forest communities in Greece. It is based on the multivariate analysis of more than 1100 relevés throughout the distribution area of Fagus in Greece, 60 % of which have been sampled within the last 15 years. The data were compiled from all relevant literature and from unpublished field studies. Prior to data analysis, taxonomic and floristic inaccuracies in older literature have been corrected, and some taxa aggregated. Status and distribution of Fagus in Greece, as well as historical and silvicultural aspects, are outlined. Classification resulted in 16 vegetation types defined by species composition, of which 10 units are ranked as association (of which two were described as new) or community, with six subcommunities included. Synonyms from the literature are given to all types. The floristic structure of the data set is displayed by a synoptic table and by DCA ordination. Community differentiation follows a complex edaphic-climatic-phytogeographic pattern. Apart from Fagus sylvatica ssp. orientalis forests of warm and dry habitats and low to medium altitudes which are related to deciduous Quercus forests, four Fagion community groups are distinguished which represent different habitat types: (1) cool, humid, mesotrophic; (2) cool, acidic; (3) high altitude, calcareous; (4) medium altitude, moderately warm and dry. The communities may be assigned to three regional suballiances, viz. (a) Doronico orientalis-Fagenion at medium altitudes of North-Central and East-Central Greece; (b) Doronico columnae-Fagenion in the far north and at high altitudes southward to East-Central Greece; (c) Geranio striati-Fagenion in the Northwest. Various types of thermophilous beech forest are assigned to (a) and (c), acidic forest to (b), and mesic Fagus forest to (b) and (c). [source]

Chloroplast microsatellites reveal colonization and metapopulation dynamics in the Canary Island pine

MOLECULAR ECOLOGY, Issue 10 2006
MIGUEL NAVASCUÉS
Abstract Chloroplast microsatellites are becoming increasingly popular markers for population genetic studies in plants, but there has been little focus on their potential for demographic inference. In this work the utility of chloroplast microsatellites for the study of population expansions was explored. First, we investigated the power of mismatch distribution analysis and the FS test with coalescent simulations of different demographic scenarios. We then applied these methods to empirical data obtained for the Canary Island pine (Pinus canariensis). The results of the simulations showed that chloroplast microsatellites are sensitive to sudden population growth. The power of the FS test and accuracy of demographic parameter estimates, such as the time of expansion, were reduced proportionally to the level of homoplasy within the data. The analysis of Canary Island pine chloroplast microsatellite data indicated population expansions for almost all sample localities. Demographic expansions at the island level can be explained by the colonization of the archipelago by the pine, while population expansions of different ages in different localities within an island could be the result of local extinctions and recolonization dynamics. Comparable mitochondrial DNA sequence data from a parasite of P. canariensis, the weevil Brachyderes rugatus, supports this scenario, suggesting a key role for volcanism in the evolution of pine forest communities in the Canary Islands. [source]

Using topographic wetness index in vegetation ecology: does the algorithm matter?

APPLIED VEGETATION SCIENCE, Issue 4 2010
Martin Kopecký
Abstract Questions: How important is the choice of flow routing algorithm with respect to application of topographic wetness index (TWI) in vegetation ecology? Which flow routing algorithms are preferable for application in vegetation ecology? Location: Forests in three different regions of the Czech Republic. Methods: We used vegetation data from 521 georeferenced plots, recently sampled in a wide range of forest communities. From a digital elevation model, we calculated 11 variations of TWI for each plot with 11 different flow routing algorithms. We evaluated the performance of differently calculated TWI by (1) Spearman rank correlation with average Ellenberg indicator values for soil moisture, (2) Mantel correlation coefficient between dissimilarities of species composition and dissimilarities of TWI and (3) the amount of variation in species composition explained by canonical correspondence analysis. Results: The choice of flow routing algorithm had a considerable effect on the performance of TWI. Correlation with Ellenberg indicator values for soil moisture, Mantel correlation coefficient and explained variation doubled when the appropriate algorithm was used. In all regions, multiple flow routing algorithms performed best, while single flow routing algorithms performed worst. Conclusions: We recommend the multiple flow routing algorithms of Quinn et al. and Freeman for application in vegetation ecology. [source]

Characterization of diverse plant communities in Aspen Parkland rangeland using LiDAR data

APPLIED VEGETATION SCIENCE, Issue 3 2007
Jason G. Su
Moss (1983) Abstract Question: How effective is high-resolution airborne LiDAR technology for quantifying biophysical characteristics of multiple community types within diverse rangeland environments? Location: Native Aspen Parkland vegetation in central Alberta, Canada. Methods: Vegetation within 117 reference plots stratified across eight types, including forest, shrubland, upland grassland and lowland meadow communities, were assessed in 2001 for the height, cover and density of vegetation within various strata (herb, shrub and tree layers). Actual ground data were subsequently compared against modelled values for each community type and strata derived from the analysis of airborne LiDAR data obtained in 2000. Results: LiDAR data were effective for quantifying vegetation height, cover and density of the overstory within closed- and open Populus forest communities. However, LiDAR measurements typically underestimated the height and cover of shrublands, as well as most of the herbaceous communities. Analysis of LiDAR intensity data indicated reflectance generally decreased as LiDAR sampling points moved upwards from the ground to the vegetation canopy. Conclusions: While LiDAR technology is useful for characterizing deciduous forest properties, the quantification of understory vegetation characteristics, as well as those of individual shrublands and grasslands, was more limiting. Further refinements in analysis methods are necessary to increase the reliability of characterizing these communities. [source]

Disturbance processes and spatial patterns of two emergent conifers in New Caledonia

AUSTRAL ECOLOGY, Issue 4 2005
LESLEY S. RIGG
Abstract Araucaria laubenfelsii Corbasson and Araucaria montana Brongn et Gris are emergent conifers in maquis and forest communities which are subjected to a combination of fire and cyclonic disturbances. Both species are able to survive fire once stems reach a critical size, but most seedlings and saplings are killed. Both species were found to be clumped at most spatial scales for both saplings and trees in maquis, probably resulting from a combination of patchy fire and a limited ability to disperse seeds. Comparisons of burned and unburned A. montana sites suggest that clumping increases only slightly after fire. The degree of clumping in the A. laubenfelsii sites, suggested that fire disturbances may occur relatively frequently in the region. Cyclonic disturbances are infrequent but may result in blow-down of large individuals within both maquis and forest. All of the individuals blown-down during the study had been previously fire-scarred. Around tree blow-downs, seedling and sapling densities can be high. This likely reflects both the low dispersability of Araucaria seeds and enhanced moisture from the shading of the adult, when it was alive. Disturbance by fire and wind play an important role in the regeneration dynamics and spatial pattern of these species in maquis in New Caledonia. [source]

Response of recruitment to light availability across a tropical lowland rain forest community

JOURNAL OF ECOLOGY, Issue 6 2009
Nadja Rüger
Summary 1. ,Many hypotheses about species coexistence involve differential resource use and trade-offs in species' life-history traits. Quantifying resource use across most species in diverse communities, although, has seldom been attempted. 2. ,We use a hierarchical Bayesian approach to quantify the light dependence of recruitment in 263 woody species in a 50-ha long-term forest census plot in Panama. Data on sapling recruitment were obtained using the 1985,1990 and 1990,1995 census intervals. Available light was estimated for each recruit from yearly censuses of canopy density. 3. ,We use a power function (linear log,log relationship) to model the light effect on recruitment. Different responses of recruitment to light are expressed by the light effect parameter b. The distribution of b had a central mode at 0.8, suggesting that recruitment of many species responds nearly linearly to increasing light. 4. ,Nearly every species showed increases in recruitment with increasing light. Just nine species (3%) had recruitment declining with light, while 198 species (75%) showed increasing recruitment in both census intervals. Most of the increases in recruitment were decelerating, i.e. the increase was less at higher light (b < 1). In the remaining species, the response to light varied between census intervals (24 species) or species did not have recruits in both intervals (41 species). 5. ,Synthesis. Nearly all species regenerate better in higher light, and recruitment responses to light are spread along a continuum ranging from modest increase with light to a rather strict requirement for high light. These results support the hypothesis that spatio-temporal variation in light availability may contribute to the diversity of tropical tree species by providing opportunities for niche differentiation with respect to light requirements for regeneration. [source]

Seedling regeneration, environment and management in a semi-deciduous African tropical rain forest

Plant traits as predictors of woody species dominance in climax forest communities

Foliar demand and resource economy of nutrients in dry tropical forest species

JOURNAL OF VEGETATION SCIENCE, Issue 1 2001
C.B. Lal
Important phenological activities in seasonally dry tropical forest species occur within the hot-dry period when soil water is limiting, while the subsequent wet period is utilized for carbon accumulation. Leaf emergence and leaf area expansion in most of these tree species precedes the rainy season when the weather is very dry and hot and the soil cannot support nutrient uptake by the plants. The nutrient requirement for leaf expansion during the dry summer period, however, is substantial in these species. We tested the hypothesis that the nutrients withdrawn from the senescing leaves support the emergence and expansion of leaves in dry tropical woody species to a significant extent. We examined the leaf traits (with parameters such as leaf life span, leaf nutrient content and retranslocation of nutrients during senescence) in eight selected tree species in northern India. The concentrations of N, P and K declined in the senescing foliage while those of Na and Ca increased. Time series observations on foliar nutrients indicated a substantial amount of nutrient resorption before senescence and a ,tight nutrient budgeting'. The resorbed N-mass could potentially support 50 to 100% and 46 to 80% of the leaf growth in terms of area and weight, respectively, across the eight species studied. Corresponding values for P were 29 to 100% and 20 to 91%, for K 29 to 100% and 20 to 57%, for Na 3 to 100% and 1 to 54%, and for Ca 0 to 32% and 0 to 30%. The species differed significantly with respect to their efficiency in nutrient resorption. Such interspecific differences in leaf nutrient economy enhance the conservative utilization of soil nutrients by the dry forest community. This reflects an adaptational strategy of the species growing on seasonally dry, nutrient-poor soils as they tend to depend more or less on efficient internal cycling and, thus, utilize the retranslocated nutrients for the production of new foliage biomass in summer when the availability of soil moisture and nutrients is severely limited. [source]