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Mountain forest ecosystems are vital for maintaining nature’s contribution to people and human well-being. Over the last few decades’ threat to biodiversity due to human induced degradation have had a major impact on moist temperate mixed broad leaved forests of Central Himalaya. Study was carried out and compared to understand the forest structure and regeneration in a protected forest (Alnus nepalensis stand), community forest (Lyonia-Rhododendron stand) and reserve forest (Quercus floribunda stand) in Upper Kedarnath valley of Uttarakhand. A total of 34 species of trees, 28 shrub species, and 45 species of herbs were reported from these forest stands. Total tree density was higher at Q. floribunda stand and lower in A. nepalensis stand. Total tree basal area varied from 59.12 (in A. nepalensis) to 101.28 m2 ha−1 (Q. floribunda stand). The sapling, seedling, shrubs and herbs density was higher in Lyonia-Rhododendron stand than other two stands. Quercus leucotrichophora, Rhododendron arboreum, Lyonia ovalifolia, Neolitsea pallens were dominant tree species in lower girth classes in Lyonia-Rhododendron stand and A. nepalensis stand whereas, Cinnamomum tamala, Ilex dipyrena in higher girth classes were dominant in Q. floribunda stand. Cumulative Disturbance Index and Ramakrishnan Index of Stand Quality was analyzed to understand the forest stand quality. Our study provides insights to changing regeneration patterns and also stand quality of forest stands in Central Himalaya. The dominance of seral species and pioneers than climatic climax species is indication that forests are struggling from continuous encroachment that might jeopardize flow of ecosystem services from forests. There is vital need to take stock of scattered but vital scientific findings to develop scientific and appropriate planning and management of broad leaved forests in Central Himalaya.

Background Decades of fire exclusion in the southern Appalachian Mountains, USA, has led to changing forest structure and species composition over time. Forest managers and scientists recognize this and are implementing silvicultural treatments to restore forest communities. In this study, conducted at the southern Appalachian Fire and Fire Surrogate Study site in Green River Game Land, North Carolina, USA, we assessed the effects of four fuel-reduction methods (burned four times, B; mechanical treatment two times, M; mechanical treatment two times plus burned four times, MB; and control, C) on the changes in understory community from pre-treatment to post-treatment years (2001 to 2016). We used non-metric multidimensional scaling (NMDS) to determine overall understory community heterogeneity, agglomerative hierarchical cluster analyses (AHCA) to determine finer-scale changes in understory community structure, and indicator species analyses (ISA) to identify the species that were associated with the different fuel reduction treatments over time. Results The NMDS ordination showed little separation between treatment polygons. The AHCA resulted in two main categories of understory species responses based on how treatment plots clustered together: (1) species apparently unaffected by the treatments (i.e., no treatment pattern present within cluster); and (2) species that responded to B, M, or MB treatments (i.e., pattern of treatment plots present within cluster). Nearly half (49.2%) of tree-species plots clustered based on treatments; 60% of shrub-species plots clustered based on treatments; and 64% of herbaceous-species plots clustered based on treatments. Many plots clustered similarly in response to fire-related treatments (B and MB). The ISA identified 11 total tree species: three in B, one in M, and seven in MB; six total shrub species: two in M, and four in MB, and 17 total herbaceous species or genera: one in C, and 16 in MB. Conclusion Fire and fire surrogate treatments did not dramatically shift understory composition after 15 years. However, certain ruderal and early seral species responded positively to MB, which was the most intensive treatment. Modest understory community changes were also observed in B, suggestive of early signs of shifting composition toward a more open forest community after four burns.

Background Most of the Pinus densiflora forests, occupying the largest area, have been restored in South Korea since the 1970s. As young pioneer forests, the succession process is under way. Since the forests are distributed nationwide and are vulnerable to disturbances, the process may differ depending on the geography and/or site conditions. Therefore, we reviewed the direction, the seral communities, and the late-successional species of progressive and disturbance-driven succession nationwide in the cool-temperate zone through meta-analysis and empirical observations. Main text As a result of a meta-analysis of the direct succession and vertical structure, we found that the P. densiflora forest is in a directionally progressive succession, changing to the broadleaved forest after forming a mixed forest with its overwhelming successor, Quercus species (particularly Q. mongolica and Q. serrata). In dry stands in a relative sense, the Quercus species was favored occupying over 80% of the abundance of the succeeding species. Therefore, in dry stands, it is presumed that Quercus-dominated stage would last for a long time due to the current dominance and long life span, and eventually, it settles as Quercus-broadleaved forest with a site change. Contrary to this, it is presumed that in mesic stands where Quercus species do not occur or have low abundance, the late-successional broadleaved species settle early to form a co-dominant forest with multiple species. Due to geographical limits, the species composition of the two late-successional forests is different. Disturbances such as insect pests and fire retrogressed vulnerable P. densiflora forest for a while. However, it was mostly restored to the Quercus forest and is expected to be incorporated in the pathway of the dry stand. Conclusions We revealed the succession process of P. densiflora forests according to geography and moisture and found that stand moisture had a decisive effect on the species and abundance of the successor. Although the P. densiflora forest is undergoing structural changes, the forest is still young; so within a few decades, physiognomy is not likely to change. Therefore, the decrease in the forest area may be due to other causes such as disturbances and forest conversion rather than due to succession.

Assessment of potential forests’ threats due to multiple global change components is urgently needed since increasing exposure to them could undermine their future persistence. We aim to assess the risks to the persistence of monospecific forests in Western Mediterranean Europe posed by climate change, fire, and land-use changes (i.e., deforestation) in the short and medium terms (horizon 2040). We specifically evaluate whether the degree of risk related to the likelihood of hazard occurrence varies depending on seral stage, tree species, and climate gradients. We performed the risk assessment on forests of Catalonia (NE Spain) through a combination of correlative and process-based modeling approaches and future global change scenarios. Overall, climate suitability of forests showed a general decrease by 2040, with the exception of xeric Pinus halepensis forests mainly distributed in the driest climate of the study area. Forest stands dominated by low drought-tolerant species were at higher risk of losing climatic suitability than forests dominated by Mediterranean species. The highest fire and deforestation risks were predicted for forest stands in dry climate where human pressures are higher. Nevertheless, high deforestation risk was also attained outside the driest areas. Deforestation risk was lower in old-growth than in younger stands, whereas old-growth forests in the Wet climate or dominated by Pinus sylvestris were projected to be at higher fire risk than younger forests. Our results suggest that conservation actions should target forest stands in dry climate. Moreover, old-growth forest stands should also be prioritized due to their particular sensitivity to disturbances and their high ecological value.

We examine patterns of vegetative change in blown-down and scorched forests in the blast zone of Mount St. Helens (USA), 10–26 years after the eruption. We compare trends in community attributes in four post-eruption environments, or site types, defined by severity of disturbance, presence/absence of a protective snowpack at the time of eruption, and seral state (previously clearcut vs. mature/old forests). Permanent plots established in 1980 at 16 sites were sampled at 5- to 6-year intervals between 1989 and 2005. Data on species presence and abundance were used to characterize changes in total plant cover, life-form spectra, species diversity, species turnover, and community composition. Due to the magnitude and heterogeneity of disturbance, vegetation re-establishment was gradual and highly variable among sites. Total plant cover averaged 36–70% after 26 years. Early-seral forbs were dominant except in snow-protected sites, where surviving shrubs were most common. Tree regeneration remained sparse after 26 years (

Tropical peat swamp forests are carbon-rich ecosystems that have been threatened by high rates of land use change (LUC). Despite the ecosystem’s shifts from sequestering carbon (C) to emitting carbon, few studies have quantified the changes in ecosystem productivity associated with LUC in tropical peatlands. This study quantified net primary production (NPP) in intact peat swamp forests (PSF), logged forests (LPSF), early seral sites (ES), and smallholder oil palm plantations (OP) in a peat dome of West Kalimantan, Indonesia. All sites were dominated by peat forest prior to deforestation. The NPP of intact forests was 13.2 Mg C ha−1 year−1 making it among the world’s most productive terrestrial ecosystems, exceeding that of many tropical rainforests and similar to the most productive mangrove ecosystems (12.9 Mg C ha−1 year−1). Land cover change resulted in large shifts in NPP. Logged forest and early seral sites were

Biota dependant on early seral stages or frequently disturbed habitats belong to the most rapidly declining components of European biodiversity. This is also the case for Carabus nitens, which is threatened across Western and Central Europe. We studied one of the last remaining populations of this ground beetle in the Czech Republic, which inhabits post-extraction peat bogs. In line with findings from previous studies, we show that C. nitens prefers patches characterized by higher light intensity and lower vegetation cover. Abundance of females was positively correlated with the cover of plant species requiring higher temperature. In addition, we demonstrate its preference for periodically moist, but not wet or inundated plots, suggesting that the transition between dry heathland and wet peat bog might be the optimal habitat for this species. This hypothesis is further supported by results showing a positive correlation between the abundance of C. nitens and vegetation cover comprising of a mix of species typical for heathland, peat bog, and boreal habitats. Our results show that C. nitens mobility is comparable to other large wingless carabids. The maximum covered distance was ~ 500 m in a month. To ensure the survival of this population, sites of recent peat extraction should be spared from reclamation and afforestation. In contrast, active measures should be taken to facilitate nutrient removal, disturbance of vegetation cover, and the creation of depressions with a humid microclimate. These actions will create a mosaic of heath, bog, and bare ground, which seems to be the preferred habitat of C. nitens at our study site.

Fire was the dominant ecological process controlling forest structure and succession in western North American conifer forests for thousands of years. Because fires are now suppressed, and because widespread logging has greatly altered vegetation structure, land managers often use estimates of pre-Euro-American settlement forest conditions to help guide restoration actions. It follows that it is important to fully understand the characteristics of pre-Euro-American settlement fire regimes. Percentages of high-severity fire, fire rotation period, and proportions of early, mid, and late developmental forests are intricately and inextricably linked. Early twentieth century vegetation maps that appear to reflect aspects of pre-settlement forest conditions demonstrate that large patches of montane chaparral, which is often an early seral community in yellow pine-mixed conifer forests, were mostly restricted to steep south-facing canyon slopes at higher elevations associated with fir or subalpine forests. When resampled to a 16 ha minimum mapping unit, we found that an early twentieth century vegetation map shows montane chaparral occupied only about five percent of the landscape outside of areas that were highly impacted by gold rush era mining. We found that successional modeling suggests that similar levels (7 %) of high severity per fire in pre-settlement yellow pine-mixed conifer forests in the Sierra Nevada would permit about half of the forested area to reach late development state, consistent with other estimated amounts of pre-settlement old-growth forests. In contrast, we found that high levels (30 %) of high severity per fire—the current average—would result in only about 13 % of forests in a late development state. We do not see evidence that large proportions of high-severity fire were typical during pre-settlement fires in yellow pine-mixed conifer forests in our study area.

Following disturbances, early-seral stages of forests provide a variety of structures. Whether this variety is a short-term phenomenon or influences forest succession for several decades or even longer is not known. We tested the hypotheses that after spruce dieback caused by bark beetles, a high spatial heterogeneity of stand structures will persist within stands and among stands even in advanced early-seral stages and that species taxonomical and functional diversity measures will reflect this heterogeneity. We used a chronosequence of unmanaged forests in the Berchtesgaden National Park (Germany) consisting of mature undisturbed spruce stands (control), stands belonging to an initial early-seral stage (~3 years after disturbance) and stands in an advanced early-seral stage (~20 years after disturbance). We analysed diversity and heterogeneity of these forest stands including stand structure, species density, species composition and functional–phylogenetic diversity of vascular plants, wood-inhabiting fungi and saproxylic beetles within plots, among plots of the same successional stage and among stages. Stands of the advanced early-seral stage were characterized by a high spatial heterogeneity of structural attributes, such as crown cover, regeneration density and spatial distribution of trees. Among-plot taxonomic beta diversity was highest in the advanced early-seral stage for beetles, but lowest for fungi, while beta diversity of plants among plots remained unchanged during succession. The mosaic of successional stages initiated by bark beetles increased the gamma diversity of the study area, especially for fungi and beetles. Our findings support the hypothesis that structural heterogeneity continues for at least two decades at stand and landscape scales and that species turnover among successional stages is a major mechanism for gamma diversity in forests after bark beetle disturbance.

This study was conducted in order to examine the influence of long-term volcanic activity on vegetative succession and growth on the slope of Sakurajima in southern Kyushu, Japan. We investigated the vegetation, depth of the volcanic ash layer, and dry density and pH of the surface soil at six places on the north-northwestern slope, 2.3–3.4 km from the Minami-dake crater, where a layer of pumice stone was deposited by the Taisho eruption in 1914. The height and diameter at breast height (DBH) of the trees increased with increasing distance from the Minami-dake crater, as did the number of individuals and species, and basal area. The Shannon–Wiener diversity index (H′) demonstrates that vegetative succession is significantly affected by distance from the Minami-dake crater, as areas farther from the crater exhibited later seral stages. Comparison of the diversity index and species number of the crater region with that of the climax forest in Kagoshima indicates that vegetative growth alone cannot advance succession in the study area, as the local vegetative community is heavily influenced by the harsh environmental conditions associated with continual exposure to long-term volcanic activity. Seral stage, ash layer depth, dry density, and pH of the soil surface layer are governed by distance from the Minami-dake crater. The results of this study indicate that conditions for vegetative growth and succession improve with increasing distance from the source of constant volcanic activity. Thus, soil development is promoted by the acidification of the soil, which decreases the dry density and pH of the soil surface layer. The introduction of plant species resistant to volcanic ash and gas is recommended to promote soil development and improve the infiltration capacity of the soil.

We sought to understand the relationship between the seed bank and vegetation in abandoned rice paddies in South Korea, in order to guide management of these sites. We investigated the floristic composition and species richness of the soil seed bank and ground vegetation in former paddies along three seral gradients (wet meadow, young forest, and mature forest) in Gwangneung Forest Biosphere Reserve. Seed bank samples contained 59 species, of which the dominant families were Cyperaceae, Gramineae, and Polygonaceae. Species richness and seedling density (59 taxa and 19,121 germinants from all samples) were high. Carex spp. (11, 921 germinants) were the dominant taxa. The species composition in the seed bank changed gradually as the land transitioned from wet meadow to mature forest. Sorensen’s index of similarity between above- and below-ground vegetation was 29.3% for wet meadow, 10.8% for young forest, and 2.1% for mature forest. Germinant density also declined, with 10, 256 germinants for wet meadow, 6445 germinants for young forest, and 2420 germinants for mature forest. Changes in aboveground environment and life history traits such as amphicarpic plants, likely affect the composition of soil seed bank species. Abandoned paddy fields may be good sites for restoration of wetland forest and conservation of wetland habitat. Some intervention may be required to promote the recovery of a natural species assemblage.

We investigated successional vegetation on river sediments along the Nakdong River in South Korea at the time when a river regulation project, named the Four River Project, was launched. We sampled differently aged stages of succession in 63 plots of 10 × 10 m in 2010 using species cover estimations. To explain the observed species composition, we considered the following environmental variables: successional age, distance from the estuary, altitude, elevation above the river water line, texture of the substrate (silt, sand and gravel content) and cover of forest around each site within a radius of 1 km. We used ordination techniques to relate plant community characteristics to environmental variables. We distinguished three main successional vegetation types based on their floristic composition, which included especially a variety of willow species. Besides the cover of forest and certain components of substrate texture, all the variables exhibited significant effects on species composition of the vegetation over the course of succession. The most important factors determining the seral vegetation were the altitudinal gradient and successional age. Environmental factors in the riverine landscape together form a complex riverine environment and determine the vegetation pattern. Unfortunately, this environment has been largely destroyed by the massive river regulation project, but our results indicate that, under certain conditions, the riverine vegetation has a potential to at least partly recover even after such a large-scale disturbance.

Glucocorticoids are thought to be related to habitat quality and may provide information about the relative health of individuals. We used a model selection approach to test whether plasma glucocorticoid levels of the Swainson's thrush (Catharus ustulatus) were associated with two attributes that may reflect breeding habitat quality in coniferous plantation forests: stand age and vegetation cover. For baseline corticosterone, the top model included stand age with limited support for models that included vegetation cover. Mean baseline corticosterone for terri- torial male thrushes sampled in mature stands was 78.2 % higher than territorial males sampled in early seral stands. For handling-induced corticosterone, there was limited separation among candidate models, and only one model, containing stand age and Julian day, was better supported than the null model. Despite previous research that has shown hardwood cover is an important component of breeding habitat quality for thrushes, our investigation found limited evidence that vegetation cover was associ- ated with either baseline or handling-induced corticoste- rone levels. Given that early seral and mature conifer forests are characterized by markedly different habitat features, we hypothesize that the observed differences in baseline corticosterone represent either reduced fitness of male thrushes in mature stands or an adaptive adjustment of glucocorticoid levels to match local environmental conditions that equalize fitness across stands of different ages.

Northern Bobwhite Colinus virginianus chicks require ample invertebrates for growth and feather development. Early successional or resprouting vegetation provides invertebrates for chicks but may not provide other resources such as roosting and loafing cover that is typically provided by later successional stages. Thus, management for bobwhites provides multiple seral stages in close proximity but the effects of landscape interspersion have not been tested for bobwhite broods. During a 2-year study, we explored the effects of landscape complementation and food availability on growth and survival of bobwhite chicks. We found growth of chicks to be negatively related to home range size which was negatively correlated to the amount of area burned. We also found survival of chicks to be positively related to the amount of burned area (i.e., foraging area) within brood home ranges. To maximize the growth and survival of bobwhite chicks, it would be necessary to increase access to foraging areas while decreasing the size of brood home ranges. Access to foraging areas can be created through frequent prescribed fire at small spatial scales.

In Rocky Mountain forests, fire can act as a mechanism of change in plant community composition if postfire conditions favor establishment of species other than those that dominated prefire tree communities. We sampled pre and postfire overstory and postfire understory species following recent (1988–2006) stand-replacing fires in Glacier National Park (GNP), Montana. We identified changes in relative density of tree species and groups of species (xerophytes vs. mesophytes and reseeders vs. resprouters) in early succession. Postfire tree seedling densities were adequate to maintain prefire forest structure, but relative densities among species were variously changed. Changes were directly related to individual species’ response to severe fires. Most notably, relative density of the mesophytic resprouter quaking aspen (Populus tremuloides) and the xerophytic reseeder lodgepole pine (Pinus contorta) increased substantially following fire, with a concomitant decline in proportional abundance of other tree species that, in some cases, dominated stands before fire. Trends identified in our study suggest that forest community shifts toward those dominated by lodgepole pine and quaking aspen are occurring in GNP. Cover of understory species was not affected by tree species composition or density. These forest communities will likely change throughout succession with the addition of shade-intolerant species in early seral stages and shade-tolerant species later in succession. However, with increased fire frequency, the lodgepole pine-dominated postfire communities observed in our study may become more common throughout time.

Plant biomass, species diversity and net primary productivity are presented for herb layer of banj oak (Quercus leucotrichophora A. Camus)-chir pine (Pinus roxburghii Sarg.) mixed forest in Kumaun, central Himalaya, India. The species diversity declined from a maximum (3.56) in September to a minimum (2.11) in December. The monthly live shoots biomass exhibited a single peak growth pattern with highest live shoot biomass of 185 g·m−2 in August. The seasonal pattern showed that the maximum above-ground production (131 g·m−2) occurred during the rainy season and the minimum (1 g·m−2) during winter season. The below-ground production was maximum during winter season (84 g·m−2) and minimum during summer season (34 g·m−2). The annual net shoot production was 171 g·m−2 and total below-ground production was 165 g·m−2. Of the total input 61% was channeled to above-ground parts and 39% to below-ground parts. Transfer of live shoots to dead shoots compartments and that of dead shoots to litter compartments was 61% and 66%, respectively. The total dry matter disappearance was 61% of the total input within annual cycle. The herb layer showed a net accumulation of organic matter, indicating the seral nature of the community.

Dune and heathland ecosystems can harbour a multitude of specialized insect species. To assess the habitat quality of these ecosystems, the presence of specialized insect species may act as a useful indicator. The Orthoptera species Myrmeleotettix maculatus, Decticus verrucivorus, and Platycleis albopunctata present such umbrella species. Because knowledge of oviposition and nymphal habitats of these species is insufficient, we conducted a combined study consisting of an outdoor oviposition experiment and a field survey analyzing nymphal habitat preferences during summer 2009 on the Baltic island of Hiddensee, Germany. The oviposition experiment showed, that all three species mostly avoid oviposition under lichens (= mature grey dunes). M. maculatus preferred bare ground for oviposition, D. verrucivorus favoured both bare ground and mosses, and P. albopunctata laid most eggs into mosses. Young nymphs of both M. maculatus and P. albopunctata preferred initial grey dunes with a high proportion of bare ground and moss-rich grey dunes. Old nymphs were related to moss-rich and lichen-rich grey dunes with more dense vegetation. Based on our results, early seral stages of dune succession with bare ground and mosses as keystone structures are crucial for the conservation of the three studied umbrella species. Because old nymphs and adults additionally require more dense grey dune vegetation or adjacent heath stands, practical dune and heathland management measures should aim to maintain a mosaic-like pattern of different grey dune and dwarf-shrub vegetation stands.

Sweetclover (Melilotus alba) is a non-native legume that has formed dense and extensive patches along several rivers in Alaska. Our research objective was to determine if sweetclover impacts recruitment of native seedlings in floodplain habitats. To determine if sweetclover impacted recruitment, we conducted a removal experiment along two rivers in interior Alaska. When compared to areas where sweetclover was removed, areas with sweetclover had approximately 50% greater mortality of native seedlings, 25% less recruiting species, and a significant reduction in the quantity of light available to seedlings on floodplain surfaces. To determine if sweetclover shading was a mechanism that limited seedling recruitment, we grew eight common early-successional floodplain plant species in a greenhouse under a range of lighting conditions that were representative of shading under sweetclover. We observed that species restricted to the earliest seral stages of floodplain succession experienced greater reductions in biomass than species that persist into later stages of floodplain succession. Shading seedlings in a greenhouse did not lead to mortality during the growing season. However, when seedlings were over-wintered, we observed that greater shading during the growing season can result in higher seedling mortality. Our study indicates sweetclover invasions have created a novel shade environment in early seral floodplain plant communities, which has the potential to alter community composition. To preserve biodiversity and structure of plant communities, sweetclover should be actively managed to prevent its spread onto additional glacial rivers in Alaska.

In the boreal forest, fire, insects, and logging all affect spatial patterns in forest age and species composition. In turn, spatial legacies in age and composition can facilitate or constrain further disturbances and have important consequences for forest spatial structure and sustainability. However, the complex three-way interactions among fire, insects, and logging and their combined effects on forest spatial structure have seldom been investigated. We used a spatially explicit landscape simulation model to examine these interactions. Specifically, we investigated how the amount and the spatial scale of logging (cutblock size) in combination with succession, fire, and spruce budworm outbreaks affect area burned and area defoliated. Simulations included 30 replicates of 300 years for each of 19 different disturbance scenarios. More disturbances increased both the fragmentation and the proportion of coniferous species and imposed additional constraints on the extent of each disturbance. We also found that harvesting legacies affect fire and budworm differently due to differences in forest types consumed by each disturbance. Contrary to expectation, budworm defoliation did not affect area burned at the temporal scales studied and neither amount of logging nor cutblock size influenced defoliation extent. Logging increased fire size through conversion of more of the landscape to early seral, highly flammable forest types. Although logging increased the amount of budworm host species, spruce budworm caused mortality was reduced due to reductions in forest age. In general, we found that spatial legacies do not influence all disturbances equally and the duration of a spatial legacy is limited when multiple disturbances are present. Further information on post-disturbance succession is still needed to refine our understanding of long-term disturbance interactions.

This study was carried out in forestland of Camili Biosphere Reserve (CBR) area in NE Turkey. It was designed to evaluate the consequences of disturbances on changes in secondary forest succession from 1985 to 2005 for monitoring forest plant biodiversity changes and developing conservation strategies. The successional stages were mapped using Geographic Information System (GIS), Global Positioning System (GPS), aerial photos and high resolution satellite images (IKONOS). The results showed that stable stage decreased about 77.96% over the last 20-year time period. Although 701.6 ha conifer forests existed in competition and reaction stages in 1985, none existed in 2005. In overall, about 33.23% of the area decreased, 42.36% did not change and 24.41% increased in different seral stages. Consequently, 8.83% of the area decreased as a whole to indicate that the forest has been developing from stable to nudation stage, that is to say, retrogressive succession is going on in the area. Forest structure and its relationship with plant biodiversity along with its changes over time were determined using FRAGSTATS. We also investigated spatio-temporal configuration of six secondary forest successional stages and generated structural diversity measures. These measures revealed that the landscape has been fragmented, posing a danger to lose the important components of plant biodiversity. Sustainable management of such degraded forests is of crucial importance for plant biodiversity conservation. In conclusion, the study contributes to the development of a framework for effective conservation of plant biodiversity through plant biodiversity integrated Multiple Use Forest Management (MUFM) plans by using the successional stages and plant biodiversity changes.

Many factors associated with forests are collectively responsible for controlling ectomycorrhizal (ECM) fungal community structure, including plant species composition, forest structure, stand age, and soil nutrients. The objective of this study was to examine relationships among ECM fungal community measures, local soil nutrients, and stand age along a chronosequence of mixed forest stands that were similar in vegetation composition and site quality. Six combinations of age class (5-, 26-, 65-, and 100-year-old) and stand initiation type (wildfire and clearcut) were replicated on four sites, each representing critical seral stages of stand development in Interior Cedar-Hemlock (ICH) forests of southern British Columbia. We found significant relationships between ECM fungal diversity and both available and organic P; available P was also positively correlated with the abundance of two ECM taxa (Rhizopogon vinicolor group and Cenoccocum geophilum). By contrast, ECM fungal diversity varied unpredictably with total and mineralizable N or C to N ratio. We also found that soil C, N, available P, and forest floor depth did not exhibit strong patterns across stand ages. Overall, ECM fungal community structure was more strongly influenced by stand age than specific soil nutrients, but better correlations with soil nutrients may occur at broader spatial scales covering a wider range of site qualities.

Aechmea bracteata is a common epiphytic bromeliad found in symbiosis with many other species throughout tropical forests of Mexico and south through Panama. Given its importance and distribution in these forests, we asked how may A. bracteata be restored to areas where they have thrived in the past? We first investigated seed viability and response of seed germination to temperature, humidity, vapour pressure deficit (VPD), and light, under controlled growth chamber conditions. We recorded these environmental conditions within a seasonal tropical forest where this species is common and then conducted seed germination trials in various seral stages. In growth chambers, with constant water supply, highest germination percentages were at the highest temperature and lowest VPD levels. In the field, germination was less than 1%. Because of high temperatures and VPD within early seral stages, efforts to re-introduce A. bracteata into forests

We investigated seasonal fluctuation patterns in species and individuals of adult butterflies and flowering plants providing nectar in a semi-natural grassland in central Japan. We considered their interrelationships and implications for conservation. The semi-natural grassland included different vegetation structures and management regimes, including: (1) firebreaks where the grass was mowed and removed, (2) plantation areas that were mowed, (3) unpaved roads with mowed banks, (4) abandoned grassland, (5) scattered scrub forest, and (6) the surrounding forest. The sites with management (e.g., firebreaks), plantations and banks of the unpaved road sustained a larger number of butterflies and flowers than sites without management, such as the abandoned grassland, scrub forest and surrounding forest. The number of butterflies increased in the firebreak in June and at all sites in August and September. The firebreak sustained flowers in the spring, and the plantation area and banks of the unpaved road sustained flowers primarily in August and September, which was correlated with the distribution of butterflies. The different treatments such as mowing or mowing with removal of grass induced different numbers of flowers of each species affecting the habitat of adult butterflies through a season. On the other hand, the shrub tree species composing the scrub forest were host plants for the larvae of certain butterfly species. Our results suggest that heterogeneous environments with different human management or different vegetation structure or both could support habitat for various butterfly species, depending on the season and the seral stage.

This study aims to investigate the change in spatial-temporal configuration of secondary forest succession and generate measurements for monitoring the changes in structural plant diversity in Yalnizçam Scots pine forest in NE Turkey from 1972 to 2005. The successional stages were mapped using the combination of Geographic Information System (GIS), Global Positioning System (GPS), aerial photos and high resolution satellite images (IKONOS). Forest structure and its relationship with structural plant diversity along with its changes over time were characterized using FRAGSTATS. In terms of spatial configuration of seral stages, the total number of fragments increased from 572 to 735, and mean size of patch (MPS) decreased from 154.97 ha to 120.60 ha over 33 years. The situation resulted in forestation serving appropriate conditions for plant diversity in the area. As an overall change in study area, there was a net increase of 1823.3 ha forest during the period with an average annual forestation rate of 55.25 ha year(-1) (0.4% per year). In conclusion, the study revealed that stand type maps of forest management plans in Turkey provide a great chance to monitor the changes in structural plant diversity over time. The study further contributes to the development of a framework for effective integration of biodiversity conservation into Multiple Use Forest Management (MUFM) plans using the successional stages as a critical mechanism.

Changes in agricultural practice are predicted across the UK following agricultural reform driven by government policy. The suitability of agri-environment schemes for many species is currently debated because limited quantitative data are collected. In order to understand the changes to biodiversity due to agri-environment schemes, there is a need for studies to not just compare biodiversity and species composition in and out of agri-environment areas, but to factor in the influence of temporal habitat changes. In this study, we investigate the suitability of an agri-environment initiative to support and enhance a small mammal fauna among pastoral hill farms in mid-Wales. Grazed and ungrazed woodlands, riparian habitats, and broadleaf plantations, were compared for small mammal abundance and diversity following a trapping study. Mammal diversity was similar across habitats, though abundance varied significantly. A principle component analysis identified that mammal abundance clustered into three main habitat groups separated by seral stage (early, mid, late). No relationship between mammal abundance and stock grazing was found. A canonical correspondence analysis confirmed that vegetation structure was important in explaining the distribution of captures of mammal species across the landscape. The results for habitat type, and habitat context, suggest that a mix of vegetation seral stages, reflecting a varied vegetation structure, is important to maintain small mammal diversity and abundance across the study area. Heterogeneity in structural diversity at the landscape scale is important to maintain a variety of ground-dwelling mammal species, and particularly because trends in countryside surveys show that woodlands are skewed towards late seral stages. Habitat heterogeneity can be maintained because the hill farms neighbour each other, and the farmers co-operate as a group to manage the landscape. Habitat diversity is therefore possible. These results help us to advocate, and anticipate, the benefits of groups of farms within a landscape.

The floodplain herbaceous vegetation of the Parana River (Argentina) was destroyed by a catastrophic extraordinary flood in 1982-83. The main communities were Panicum prionitis tall grasslands. According to a succession model, they were seral communities that would have evolved to hygrophilous forest. After the flood, the area was surveyed in 1984, 1988 and 2002 and analyzed with numerical methods. First, the area was invaded by a community of annual species, which were the sparse species of tall grasslands, but five years after the colonization this community disappeared and was replaced by the original tall grasslands and turfs. The tall grasslands rapid recovery and the absence of woody species support the hypothesis that this community is a stable community which was rejuvenated by catastrophic floods and was prevented to develop into woody species communities.

We investigated ectomycorrhizal (EM) fungi in forest stands containing both early successional Douglas-fir and late successional western hemlock at two points in the typical stand development by identifying EM fungi from roots of Douglas-fir and western hemlock in mixed stands. In an early seral stage forest, EM roots of western hemlock seedlings and intermingling 40-year-old Douglas-fir were sampled. In a late seral stage forest, EM roots of trees of both species were sampled in a 400-year-old stand. We use molecular approaches to identify the symbionts from field samples in this descriptive study. In the early seral stage study, >95% of the western hemlock root tips by biomass were colonized by fungi also colonizing Douglas-fir roots. This result supports the prediction that western hemlock can associate with fungi in Douglas-fir EM networks. In the same study, fungi specific to Douglas-fir colonized 14% of its EM root tips. In the late seral stage study, 14% of the western hemlock root tips were colonized by fungi also observed in association with Douglas-fir, a result strongly influenced by sampling issues and likely represents a conservative estimate of multiple host fungi in this old growth setting. Fungi specific to Douglas-fir colonized 25% of its root tip biomass in the old growth study, in tight coralloid clusters within five of the 24 soil samples. The trends revealed in this study corroborate earlier studies suggesting a predominance of multiple host fungi in mixed communities of EM plants. The role of host-specific fungi in these stands remains unclear.

In the Cerrado savannas from Brazil fire events are common and strongly influence the vegetation structure and, consequently, the associated small mammals. In this paper, we investigate changes in the structure of small mammal communities related to sites of different post-fire ages. Mammals were captured in similar Cerrado sites that differed in time since the last burn (1 to 26 yr). We sampled six sites in the wet season of 1997 (phase 1) and, three years later, six sites in the wet and dry seasons (phase 2). Six rodent species and four marsupials were captured. Community composition changed drastically as a function of time since fire. The diversity and abundance of small mammals reached maximum values in the early successional stages. The rodent Calomys tener was present only in early seral stages. The rodent Bolomys lasiurus was more frequent in mid-successional stages and decreased in later seral stages, and the rodent Oryzomys subflavus occupied all successional stages. The marsupial Gracilinanus agilis was dominant in the area that did not burn for at least 23 yr. Changes in composition of the community of small mammals were more accelerated in early successional stages, when there are more drastic vegetational changes. The ability of small mammals to cope with Cerrado fires and the great dissimilarity among post-burning seral stages suggest that a mosaic of areas representing different post-fire seral stages could increase the regional diversity of this group.

To test the hypothesis that primate populations are limited by food resources, we studied the feeding ecology of three cercopithecines and one colobine in a rain forest in central Gabon. Simultaneously, we monitored the fruiting phenology of trees and estimated the biomass of the monkey community. The Makande Forest is dominated by Caesalpiniaceae and characterized by a lack of secondary vegetation and of trees species producing fleshy fruits. Fruit production was irregular intra- and interannually. Fruiting peaks of dry fruits (mainly Caesalpiniaceae) and of fleshy fruits occurred at the same period. However, interseasonal and interannual variability was greater in Caesalpiniaceae than in other families. As a result, the Makande forest is subject to bottlenecks when food is scarce. On an annual basis, seeds (primarily Caesalpiniaceae) dominated the diet of all monkeys. On a seasonal basis, cercopithecines preferentially consumed fleshy fruits as long as they were available, whereas colobines increased consumption of young leaves when seed availability declined. The consumption of mature leaves was low. The monkey community biomass (ca. 204 kg/km2) is one of the lowest in Central Africa. We suggest that both cercopithecine and colobine populations are limited as a result of the combined effect of the dominance of Caesalpiniaceae, which provide dry fruits according to a mast-fruiting pattern and mature leaves of low quality, and the lack of seral successional stages, which provide fleshy fruit on a more regular pattern and leaves of better quality. During the period of food scarcity, cercopithecines should suffer from the low availability of fleshy fruit, which are their favorite food. At the same period, colobines should be limited by the low availability of edible leaves. Similar low primate biomasses are found in forests dominated by Caesalpiniaceae or Lecythidaceae in South America and in Dipterocarpaceae forests in South Asia, which suggests that their biological characteristics, in particular dry fruits and mast fruiting, are unfavorable to monkey populations. Our results confirm that habitat mosaics may support larger populations of primary consumers than homogeneous primary forests can.

The relationship between soil nitrogen (N) availability and plant community structure was investigated in old-fields in the shortgrass steppe of Colorado. Nitrogen availability was manipulated by N or sucrose additions for 4 years at three old-fields (early-seral, mid-seral, and late-seral) and at an uncultivated control site. The addition of N generally resulted in increased abundance of annual forbs and grasses relative to perennials at all of the previously cultivated sites. Conversely, experimental reduction of N availability generally increased the relative abundance of perennials. Despite a lack of detectable differences in N mineralization between sites and treatments, ion-exchange resin bags confirmed that sucrose additions reduced plant-available N and that N additions increased plant-available N. This was evidenced further by similar observations for plant tissue N content. The degree to which N additions increased N availability at the various sites supported the idea that late-seral plant communities are less effective at N capture relative to earlier-seral communities. The mid-seral old-field had the lowest rates of litter decomposition and a relatively large accumulation of litter on the soil surface. This mid-seral old-field was dominated by an exotic annual grass (Bromus tectorum), which appears to be a major hindrance to redevelopment of the plant-soil system. By experimentally reducing N availability at this stage, we were able, in 4 years, to change the plant community into one that more closely resembled the late-seral community. We also observed that the natural recruitment of weedy annual species on the uncultivated site during an unusually wet year was suppressed by reducing N availability. Our results suggest that available N is an important factor controlling the rate and course of plant and soil community redevelopment on abandoned croplands in the shortgrass steppe, and that manipulation of N availability might be useful in restoration of rangeland vegetation.

The DBH-class distribution in natural deciduous broad-leaved forests was elucidated with a power function. A power function (y=ax b, y: stem density, x: represents DBH class, a and b: constants) fits the distribution better than an exponential function (y = a exp bx). The parameter b in the power function is approximately −2. This means that the natural forests studied have a patch-mosaic structure and that tree cohorts regenerate from gaps. Parameter a implies the number of juveniles, and b means size-dependent mortality. The value of −2 for parameter b means that when trees in a given DBH class double their DBH, the density of the size class should decrease by one-fourth. This phenomenon results from self-thinning and is caused by horizontal space competition among trees, called the `tile model'. The parameter describing DBH-class distribution for a forest with self-thinning patches should be approximately −2. I call this the `−2 power law' for DBH-class distribution. In a typical natural forest dominated by deciduous broadleaf tree species, trees are recognized as pioneer or climax species by the parameters describing their regeneration patterns. When I applied the power functional model to the DBH-class distribution of each dominant species, in pioneer species parameter a was high and b was less than −2 (markedly less than zero), suggesting that there are many juveniles, but mortality is high. On the other hand, in climax species parameter a was low value and the value of b was larger (negative, but closer to zero), suggesting that there are not many juveniles, but mortality is low. A power-function analysis of DBH-class distribution can be used to clarify the patch mosaic structure of a forest, and to clarify the regeneration pattern of pioneer and climax species by applying the function for each species.

Because Pseudotsuga menziesii (Douglas fir), an early seral dominant in western Oregon forests, is particularly susceptible to the pathogenic root rot caused by the fungus Phellinus weirii, it was hypothesized that successional development in affected forests would be accelerated. The basal area of late successional tree species and common shrubs were compared inside and outside Phellinus weirii"infection centers". Future successional impacts indirectly caused by disease presence were assessed by comparing the abundance of regenerating tree species inside and outside of these centers. Results for old-growth sites in the lower Cascades supported the initial hypothesis. The presence of Phellinus weirii at these sites appears to push changes in the late successional species basal area along the same trajectory. At the Coast Range sites, however, shrub growth was greatly enhanced rather than the growth of Tsuga heterophylla (western hemlock), the only late successional tree species at these sites. Regeneration of trees was sparse in all areas and was negatively correlated with the basal area of existing western hemlock, and not directly correlated with the presence of the pathogen. However, because the basal area of western hemlock is influenced by the presence of disease in the Cascade sites, Phellinus weirii may be an influential indirect factor in the future successional direction of the sites. This study demonstrates the potential importance of native pathogens in determining the successional status of a community, as well as the importance of such biotic agents in the physical structure of multi-strata forested communities as a whole.

Roadless areas on public lands may serve as environmental baselines against which human-caused impacts on landscape structure can be measured. We examined landscape structure across a gradient of road densities, from no roads to heavily roaded, and across several spatial scales. Our study area was comprised of 46,000 ha on the Roosevelt National Forest in north-central Colorado. When forest stands were delineated on the basis of seral stage and covertype, no relationship was evident between average stand size and road density. Topography appeared to exert a greater influence on average stand size than did road density. There was a significant positive correlation between the fractal dimension of forest stands and road density across all scales. Early-seral stands existed in greater proportions adjacent to roads, suggesting that the effects of roads on landscape structure are somewhat localized. We also looked at changes in landscape structure when stand boundaries were delineated by roads in addition to covertype and seral stage. Overall, there was a large increase in small stands with simple shapes, concurrent with a decline in the number of stands > 100 ha. We conclude that attempts to quantify the departure from naturalness in roaded areas requires an understanding of the factors controlling the structure of unroaded landscapes, particularly where the influence of topography is great. Because roads in forested landscapes influence a variety of biotic and abiotic processes, we suggest that roads should be considered as an inherent component of landscape structure. Furthermore, plans involving both the routing of new roads and the closure of existing ones should be designed so as to optimize the structure of landscape mosaics, given a set of conservation goals.

A mature mangrove community was preserved at Pasir Ris during the reclamation of its foreshore by maintaining a channel (river) so that the plot could be subjected to inundation frequency of 40 to 50 times per month. By subjecting the embankments of the river and another plot of vacant reclaimed land adjacent to the mature community to a similar frequency of inundation, new mangrove communities comprising Avicennia spp and Sonneratia alba were regenerated. When the depth of the mangrove soil increased proportionately with time, succession by another seral community (Rhizophora spp) occurred. Factors affecting the development of the mangrove soil and its nutrient accumulation over time, and the regeneration of new mangrove communities through colonisation by different plant and animal species are discussed.

In human-dominated regions, forest vegetation removal impacts remaining ecosystems but regional-scale biological consequences and resource value changes are not well known. Using forest resource survey data, I examined current bottomland hardwood community types and a range of fragment size classes in the south central United States. Analyses examined resource value indicators, appraised tree-based flood zone and shade tolerance indices, and identified potential regional-scale processes. Findings revealed that the largest fragments had fewer tree species, reduced anthropogenic use evidence, and more older and wetter community types than small fragments. Results also suggested the need for incorporating hydrologic, geomorphic, and understory vegetation parameters in regional forest resource monitoring efforts. Two regional-scale processes are hypothesized: (1) forest fragmentation occurs more frequently in drier habitats and dry zone (inundated ≤ 2 months annually), younger seral stage bottomland community types; and (2) forest fragmentation induces establishment of drier habitats or dry zone, younger serai stage community types. Both hypotheses suggest that regional forest fragmentation impacts survival of distinct community types, anthropogenic uses, and multiple resource values.

We evaluated the status of the microbial biomass N pool in grassland, and in deciduous and evergreen forest soils in Chiba, central Japan. Microbial biomass N, a labile fraction of total N in the soil, ranged from 6.96 g N m-2 (15 cm depth) in the grassland to 24.8 g in the deciduous and 20.7 g in the evergreen soils, on a landscape basis. Thus the pattern in the grassland and in the forest soils differed. The N flush measured by a fumigation-incubation method indicated that in the grassland soil microbial biomass N was underestimated by a factor of 2.6 compared with the results from a fumigation-extraction method, because of heavy N immobilization in the microbial biomass. This was in contrast to results from the forest soils, which did not immobilize N. Thus, the forest soils were in a steady-state condition compared with the grassland which formed a seral phase in the ecological succession. Simple correlation coefficients indicated a significant positive relationship between biomass N and organic C in the soil and the N concentration in the litter, the main component of organic matter in the soils of the three ecosystems.

Reconstruction in twenty single-cohort stands across five climax series on the eastern slope of the Washington Cascade Range found a variety of species combinations and development patterns. Western larch (Larix occidentalis Nutt.) and lodgepole pine (Pinus contorta Dougl. ex Loud) were found to be very competitive species that usually occupied a dominant position in stands in the Abies grandis, Abies lasiocarpa, and Tsuga mertensiana climax series. Interior Douglas-fir (Pseudotsuga menziesii var. glauca (Mirb.) Franco) was found in all five climax series and, although its height growth was less than that of western larch or the lodgepole pine, it was usually found in the upper stratum. These results suggest that site classification based on climax potential should be used cautiously when applied to young stand management decisions regarding seral species. For example, the difference between an Abies grandis, and a Tsuga mertensiana climax series is quite large in terms of potential productivity but in either case western larch, if present, will likely dominate these stands.

The Gitksan and Wet'suwet'en peoples of northwest British Columbia occupy the upper drainage of the Skeena River and the western headwaters of the Fraser River. They live in a region of diverse topography, vegetation, and climate. Berry patch burning was the most important traditional vegetation manipulation. Black huckleberry and lowbush blueberry patches were burned to stimulate growth of new stems and production of berries, while preventing invasion by other shrub species and conifers. Maintenance of berry patches by burning was discontinued in the 1930s and 1940s because of fire suppression by the British Columbia Forest Service. Spring burning on south facing slopes, village sites, and garden sites was also practiced, and continues to the present. It occurs in aspen, pine, or grass dominated seral communities, or cottonwood floodplain forest, and is intended to control brush and encourage growth of grass.

Satellite Remote Sensing data has been used for vegetation mapping, initial stratification, distribution of sample plots and for calculating the area under different vegetation types. Primary and secondary analyses of vegetation has been done using phytosociological ground data collected from sample piots to assess the ecological importance of different species. Interrelationships among different communities have been evaluated through various available indices. The spatial distribution and vegetation analysis indicate that commercial extraction of natural forests of Andaman has set in retrogression. The evergreen forests subjected to shorter rotation of commercial exploitation are being invaded with seral deciduous species. The study highlights the status of forests (spatial and community) and stresses the need to conserve germplasm present in the natural evergreen forests.

The potential for mycorrhizal formation and Frankia nodulation were studied in soils from six sites in the Pacific Northwest. The sites included young and old alder stands, a 1-year-old conifer clear-cut, a young conifer plantation, and rotation-aged and old-growth conifer stands. A bioassay procedure was used with both red alder and Douglas fir seedlings as hosts. After 6 weeks growth, seedlings of both hosts were harvested every 3 weeks for 21 weeks and numbers of nodules and ectomycorrhizal types estimated. Nodules formed on red alder and ectomycorrhizae formed on both alder and Douglas fir in soil from all sites. Nodulation potential was highest in soil from the alder stands and the conifer plantation. Seven morphologically distinct ectomycorrhizal types were recovered on Douglas fir and five on alder. Only Thelephora terrestris, a broad-host-range mycobiont, formed mycorrhizae on both hosts. New ectomycorrhizal types formed on both hosts throughout the bioassay. Ectomycorrhizal colonization of alder was greatest in the alder and clear-cut soils. Low ectomycorrhizal colonization on alder was found in soils from sites where conifers were actively growing. Ectomycorrhizal colonization of Douglas fir was highest in the young alder and conifer plantation soils and was low in the rotation-aged conifer soil. The highest diversity of ectomycorrhizal types was found on alder in the conifer clear-cut soil and on Douglas fir in the rotation-aged conifer soil. Effects of host specificity, nodulation and mycorrhiza-forming potential and nodule-mycorrhiza interactions on seedling establishment are discussed in relation to seral stage dynamics and attributes of pioneer ectomycorrhizal fungal species.

Above- and below-ground biomass production, nitrogen (N) and phosphorus (P) tissue concentrations, and root: shoot ratios were examined for five species that are characteristic of a semiarid successional sequence under controlled greenhouse conditions. In two simultaneous experiments, seedlings of one forb, two grass, and two shrub species important in a sagebrush successional sere, were subjected to seven levels of N and P. Results of the experiments suggest distinct differences in nutrient response patterns between early and late seral species. Early seral species produced more biomass but had lower tissue nutrient concentrations than late seral species. As N and P availabilities decreased, late seral species displayed characteristics indicative of increasing competitive advantage over those of early seral species. Root: shoot ratios of the five species primarily reflected patterns related to lifeform, but with some early and late seral characteristics. Results from this study 1) confirm that nutrient use pattern, nutrient availability, and seral position relationships characteristic of mesic ecosystems hold equally true for semiarid systems, and 2) suggest that nutrients are important organizing factors in semiarid ecosystems.

Plant, insect and forest structures of 25 forest communities were investigated in Mao'ershan Experimental Forest Farm and Liangshui Experimental Forest Farm during 1994–1995. The paper used continuum index (Ci) as a parameter, to quantitatively describe forest community succession stage. Relationships between the biodiversity and continuum index of forest community were studied. The annual species and family diversities in forest plant community showed nonlinear correlation with continuum index, and the largest diversities were during the middle stage of succession. The diversities of total insect community and herbivorous insect group were negatively related withCi, that of spide group and parasitic insect group was positively related. The pattern diversity and coverage weight diversity index foliage height increased with continuum index.

Rangeland vegetation in the Great Basin of the United States is found in several seral stages depending upon gradients related to distance from water and grazing differences across fencelines. Detailed documentation of vegetation changes was attempted on a representative vegetation type in northern Nevada using a chronosequence approach. Frequency of occurrence appeared to be the vegetation attribute most clearly expressing an axis of change or differences across the site. Soil profile descriptions and soil analyses helped relate plant community changes to abiotic variation. Species, microtopography and soil surface characteristics varied with seral stage. Pattern analysis proved useful for relating vegetation changes to successional stages. Computer-based classification (TWINSPAN) and ordination (DECORANA) techniques defined a successional gradient that differed from a theoretical or assumed successional classification.

A study was begun in 1976 to measure succession patterns following soil disturbance within a sagebrush community in northwestern Colorado. The principal hypothesis was that type of disturbance affects the direction of succession, resulting in different plant communities over time. Successional dynamics were studied through 1988. Four types of soil disturbance resulted in 3 early seral communities: one dominated by grasses, one by annuals, and one intermediate. The annual-dominated communities were opportunistic on these sites, lasting 3-5 years and not determining the direction in which succession proceeded following their replacement. Twelve years after disturbance, 3 communities (one grass-dominated, one shrub-dominated, and one intermediate) occupied the site, the characteristics of which were functions of type of initial soil disturbance. For the period of time covered by this study (12 years), degree of disturbance was found to affect the direction of succession, resulting in different plant communities over time. There were, however, successional characteristics toward the end of the study that suggest that over a longer time period, succession might progress to a single community regardless of type of disturbance.

Previous classifications at continental to state/provincial scales were surveyed in order to produce a new classification of North American forests. This classification is of present-day forests and includes both seral and old-growth forest types. The classification is hierarchical, as physiognomically-based formation types are defined on the basis of growth form of dominant trees and subdivided into forest types according to the species of these dominants. The classification includes a total of 68 forest types and 1 complex of forest types. These are presented by formation type (9) and by forest region (11). The number of formation types is largest in forest regions where major climate types intergrade, i.e., in the United States Coastal Plain and Piedmont Lowland (6 types) and the Central American Montane (5). The number of forest types is largest in the Eastern United States Lowland (12) and the Rocky Moutain—Sierra Madre Oriental—Sierra Madre Occidental Montane (11).

Evidence of a pile-dwelling community and seral environmental conditions during the late Mid-Holocene (ca 4,000–3,000 years b.p.) is explored through archaeological data and paleoecological information from the Bilbo Site at the mouth of the Savannah River along the Georgia coast, U.S.A. It is argued that pile dwellings were a central feature of the cultural adaptive system, allowing settlements to be located in wetlands that provided optimal access to the evolving food resources of multiple, dynamic environments. It also is suggested that the adaptive strategy included residential stability and a more complex organizational structure than that exhibited by modern hunter-gatherers living in marginal environments.

To study secondary successional sequences and mechanisms, denudation experiments were conducted in Central Japan with the removal of dominants, laying burned soil on the surface, and turning over the top- and subsoil. The early stages of secondary succession were predictable as to species and life-form composition. The biomass — the degree of succession (DS) relationship and the DS-isopleth showed phasic changes within a seral stage. The rate of succession (RS) was also calculated. In the establishment of weed communities with crops, the critical time for weeding, the allowable limit of weeds, etc. were found in relation to the distribution pattern, adaptive strategy of species, interspecific and intraspecific density regulations. In seasonal denudation experiments, the month of denudation affected the regular phenological pattern of weedy species, although normal replacement of summer annuals by winter annuals was usual. The population dynamics of buried-seeds in the soil, the adaptive strategies of the dominants and the role of allelopathy were discussed as the main forces of secondary succession in its early stages.

Growth and allocation patterns of biomass and nutrients of herbaceous species from grasslands at Cherrapunji in north-eastern India were studied under varied nutrient stress situations. Though populations from a nutrient richer soil had better growth rate than those from nutrient poor sites, this difference was not reflected in the tissue concentration of nutrients. Populations in nutrient deficient soils had high allocation to the belowground organs of reproduction than for aboveground parts. ThoughIschaemum andEragrostiella had generally lower nitrogen uptake efficiencies, their use efficiency was fairly high. Soils that are generally nutrient deficient had more C4 grass components than the rich soil underOsbeckia-type.

Detailed statistical analysis of data obtained from five species of New Zealand native trees was used to develop an empirical model of pressure-volume curves. The model combines an exponential turgor function with a hyperbolic osmotic function and provides a very good fit to all data sets. The resultant function permits precise calculation of the bulk modulus of elasticity and turgor loss point from simple manipulation of the coefficients as well as providing the usual estimates of osmotic potential and free water content. The use of several water relations parameters, rather than one or two, each expressing different ecological aspects has permitted a better insight into the adaptability of the species. The data was obtained as part of an investigation into the causes of forest mortality to examine the tissue water relations of the principal species and to assess their ecological status. For all parameters highly significant differences were found between species. Silver beech (Nothofagus menziesii) and quintinia (Quintinia acutifolia) or tawari (Ixerba brexioides) are well separated and are consistently placed in opposing groups by the parameters. Osmotic potential proved to be of limited value for differentiating sites possibly because of the greater amplitude of diurnal variation compared with the site differences and also because of large within site variation. However variations in the pressure potential at the turgor loss point, which was closely correlated with osmotic potential, discriminated the levels of effective precipitation at the study sites, and the drought tolerance of the species. For one species, tawari, it proved possible to classify the sites on the basis of water content at the turgor loss point and osmotic potential using discriminant analysis. Variation in the water potential at the turgor loss point, which was closely correlated with osmotic potential, can be used to rank the species in order of drought adaptability and this was found to coincide with their order of permanence on the site. The bulk modulus of elasticity and the coefficient of elasticity are closely linked but their value in the ecological comparisons was limited by higher variability than found for other parameters. Ranking of the species using the variability of the parameters indicates the presence of to two distinct survival strategies; stress avoidance and stress tolerance. The two canopy species utilise opposing strategies and may be less at risk than the seral plants which combine both strategies. The data provides evidence for current stress on the unhealthy site which most stongly affects the seral species.