Differences In Tree Species Composition Research Articles

Vertical explorers: Unraveling vertical and horizontal patterns of vascular epiphyte diversity in a dwarf cloud forest

Vascular epiphytes are plants that grow on phorophytes, and their distribution may vary both horizontally and vertically. Understanding the factors shaping epiphyte distribution and their relationship with alpha and beta diversities is crucial for understanding richness and composition patterns. We investigated alpha and beta diversity variation in the vertical and horizontal stratification of epiphyte communities across different vegetation types in a dwarf cloud forest. Twenty-four 20 × 10 m plots were established in three vegetation types defined by distinct soil characteristics, different phorophyte height and differences in tree species composition in Parque Estadual do Ibitipoca, Minas Gerais, Brazil. Phorophytes were divided into four strata: (A) base of the trunk, (B) lower trunk, (C) inner canopy, and (D) outer canopy. Alpha and beta diversity analyses were performed for each site. We found a reduced stratification in the area, indicating minimal composition differences between the strata. However, the canopy exhibited greater species richness than the trunk. Vegetation types F1 and F2 displayed higher richness compared to F3. Orchidaceae was the richest family overall, while Bromeliaceae and Polypodiaceae were more frequent. Holoepiphytes were highly representative, demonstrating consistent patterns of richness, composition, and dispersion, with anemochorous species being the most abundant. This study highlights the unique patterns of epiphyte stratification, emphasizing the importance of biotic and abiotic characteristics in colonization processes. Despite the low canopy of the forest, the non-uniformity in stratification demonstrates that formation characteristics, such as height, play a significant role in shaping epiphyte richness and composition patterns.

Nitrate and Ammonium Deposition in the Midwestern Fragmented Forest

Whereas the impacts of N deposition on forest ecosystems have been well studied in remote areas in predominantly forested landscapes, we know relatively less about the impacts of N deposition on forests in heavily human-modified landscapes. We studied the influence of adjacent land use, local point sources, and woodlot stand structure on subcanopy N transport and enrichment via throughfall in three woodlot fragments in southern Lower Michigan, USA. We found that one site had markedly higher TF N concentrations compared to the other two; however, our data indicate that elevated TF concentrations resulted from differences in tree species composition, rather than differences in surrounding land use. Specifically, we observed that the local abundance of basswood (Tilia americana) was positively associated and the local abundance of northern red oak (Quercus rubra) was negatively associated with TF N concentrations. One site had markedly greater TF N fluxes compared to the other two, which was driven by a lack of understory vegetation, possibly due to higher deer browsing at this site. Together, the results of this study demonstrated that TF N concentrations and fluxes were more strongly influenced by the internal characteristics of fragmented woodlots, such as forest structure and species composition, than by the surrounding land use.

Forest management affects saproxylic beetles through tree species composition and canopy cover

Forest management has been shown to affect biodiversity, but the effects vary among taxa and studies. Due to their host-tree preferences, many saproxylic, i.e. deadwood-dependent, beetle species are likely affected by forest management via changes in tree species composition. However, further structural differences caused by forest management, such as microclimatic conditions, may interfere with effects of tree species. We lack a more detailed understanding of how forest management intensity influences saproxylic beetles through tree species composition and structural properties.We analyzed the effect of forest management on saproxylic beetles using an eight-year dataset collected from 379 experimental logs of 13 different tree species, which were exposed in forests of different management intensity in three regions of Germany. To quantify forest management intensity, we first used a composite index (ForMI) which considers the share of locally non-native tree species, the origin of deadwood and the harvesting rate and then replaced it by five forest structural and compositional properties. This two-step approach allowed to assess the overall effects of management summarizing different aspects and to identify the main forest attributes driving these overall effects. We further investigated whether the effects differ between beetle assemblages emerging from conifer and broadleaf logs (host level), and between generalists, conifer-specialists, and broadleaf-specialists (beetle specialization level).Abundance and species richness increased with increasing ForMI for all beetles, generalists, and conifer-specialists, but not for broadleaf-specialists.Effects of ForMI were stronger for assemblages emerging from conifer than broadleaf logs. Among the evaluated structural and compositional variables, strongest effects were observed for conifer share at stand level and canopy cover. Conifer share positively affected the species richness of all beetles, generalists and conifer specialists, but not of broadleaf specialists. Canopy cover negatively affected all beetles, generalists and conifer specialists, but did not affect broadleaf specialists.Our results show that major drivers behind effects of forest management on saproxylic beetles are differences in tree species composition and canopy cover. Effects differ between beetle groups depending on their host specialization. Forest management decisions regarding tree species composition should therefore more strongly consider their effects on saproxylic beetle diversity to meet conservation goals also in the future.

Landscape openness has different effects on the structure, diversity and functional composition of Brazilian rainforests

Landscape openness leads to harsher environmental conditions and reduced propagule dispersal, but how it affects different forest attributes and over what spatial scale remains unclear. We evaluate the effects of landscape openness (i.e., increased forest loss and fragmentation) on nine forest attributes related to structure, diversity, and composition for four different spatial scales, and three regions in Brazilian Atlantic forest. For 35 0.1 ha forest plots we calculated nine forest attributes related to structure (basal area, maximum height, structural heterogeneity), tree biodiversity (species richness, Simpson diversity, functional richness) and functional composition (proportion of animal-dispersed and shade-tolerant species, seed size). To assess at what spatial scales landscape characteristics play a role, we calculated for each plot local matrix openness and forest patch density using four concentric circles of 400 to 3200 m radius. Landscape openness negatively affected most forest attributes, but the magnitude of effect varied with 1) landscape attribute, 2) forest attribute, and 3) region. First, matrix openness had a negative stronger effect than patch density, indicating that landscape forest loss is more detrimental than forest fragmentation. Second, landscape openness reduced most strongly forest structure and animal-dispersed species, probably because open landscapes increase edge effects which especially affect large-sized trees, and reduce the abundance and activity of zoochorous seed dispersers, while landscape openness had opposite effects on diversity in different regions. Third, landscape openness had different effects in different regions, probably because of regional differences in tree species composition, landscape configuration and composition. Finally, landscape openness affected forest structural attributes at all spatial scales, animal-dispersed species at larger spatial scales (>1600 m), and seed size at small spatial scales (<400 m). In sum, landscape openness reduced most forest attributes, although the strength varied with the landscape attribute, forest attribute, and landscape context. Conservation and restoration projects should therefore restore landscape forest cover to improve forest structure, diversity and composition, and take into account the landscape context.

Pengaruh Kombinasi Kerapatan Kanopi Pohon terhadap Kenyamanan Termal di Lapangan Puputan Margarana, Denpasar

Puputan Margarana as a city park is used as a public space that can accommodate outdoor activities for its users. Comfort is an important factor consider for users to conduct activity inside. User comfort level can be measured using the thermal humidity index formula based on the temperature and humidity variables. The temperature and humidity can be influenced by the presence of vegetation, especially trees. Differences in tree species composition will cause differences in the canopy density formed. This study aims to identify the effect of the combined tree canopy density on thermal comfort. This research method begins with determining the sample point based on the combination of canopy density to areas that are not shaded by the canopy. Then, the canopy was photographed at the sample point for analysis using Hemiview 2.1 software to obtain the leaf area index (LAI) value. Furthermore, independent samples T test, assessment of thermal comfort, correlation analysis and linear regression between variables. The results of the analysis show that there is a strong correlation between LAI with temperature, humidity, and THI. There were significant differences between THI at sample points 1, 2, 4, and 5 with LAI 1.68-4.53 against THI without canopy shade. Meanwhile, THI at sample points 3 and 6 with LAI 0.96-1.36 was not significantly different from THI without canopy shade. This shows that the combination of tree canopy density in this study has an effect on thermal comfort. This shows that canopy density can be one of the considerations in selecting trees for landscape design for climate engineering purposes.

Spatial patterns and species composition of new forest areas present challenges for forest management in Latvia

Forest area increase has been characteristic to the Eastern Baltic region since the early twentieth century. The emergence of new forest areas in significant amounts changes the visual and ecological character of landscapes and affects forest management decisions. The aim of this study was to investigate how emerging spatial patterns and stand characteristics of new forest areas impact forests in Latvia. Four study areas were selected in Latvia – Skrunda, Bauska, Skujene and Kaunata to analyze new and stable forest areas. Inside these four areas, 27,205 forest compartments were analyzed from new forests and 93,902 compartments in stable forests for reference. New and stable forest areas were mapped for the period of 1967–2017. Latvian State Forest register database provided compartment-level characteristics for new and stable forests. Descriptive statistics was used to analyze differences in tree species composition, ownership structure and management restrictions; and GIS methods – to assess compartment accessibility by roads. Spatial pattern metrics were calculated using Morphological Spatial Pattern Analysis in Guidos Toolbox 2.6. Results show that the majority of new forest areas have emerged from spontaneous afforestation, this was especially pronounced in Kaunata area (only 5% of new forest areas were planted). Scots pine, Norway spruce and two birch species comprised the majority in stable forest areas compared to new forest areas, where the proportions of dominant tree species were more evenly distributed. Spatial pattern analysis showed that the emergence of new forest areas has contributed to the homogenization of forest pattern with increasing Core area, reducing Edge and Islet (isolated patch) proportion. 93–99% of new forest areas identified in this study were not state-owned. Compartment accessibility was very good for all four study areas in Latvia, with 60–80% of stands being located closer than 500 m from roads. This study demonstrated that management of such small, spatially scattered and young forest compartments can be problematic. Since the majority or Latvia’s private forest owners’ holdings are smaller than 50 ha, the lack of resources and education as well physical factors impede successful involvement of these numerous small owners in sustainable management efforts.

Short-term avian responses to experimental variable-density thinning: Initial stand attributes outweigh effects of management in Austral temperate rainforests

Anthropogenic environmental changes have led to secondary forests becoming dominant in many regions. Although ecological or restoration thinnings can help restore old-growth conditions, experimental evidence of their subsequent benefits to biodiversity remains sparse, particularly in Austral Temperate Rainforests in South America. Using mist-net sampling within 1-ha plots in mixed-evergreen and Nothofagus secondary forests, we examined short-term effects (4 years) of experimental Variable Density Thinning (VDT) on bird richness, abundance, and the individual body condition of two abundant breeding species: frugivore Elaenia albiceps and insectivore Aphrastura spinicauda. Based on 518 birds captured, richness and relative abundance were higher in Nothofagus than in mixed-evergreen forests, regardless of VDT treatment, except for E. albiceps which was more abundant in mixed-evergreen forests. Richness and abundance did not vary with VDT treatment, except for E. albiceps which increased in abundance following VDT. However, individual body condition of E. albiceps did not change due to VDT management, although it was better in mixed-evergreen than in Nothofagus forests, and increased over the course of the study. In contrast, body condition of A. spinicauda was not associated to VDT treatment, forest type, or season. Our results suggest that the short-term effects of VDT in secondary Austral Temperate Rainforests upon avian richness, abundance, and individual body condition were minimal, and that initial stand attributes (i.e. forest type) more strongly influenced these variables. This is likely due to the region’s high diversity of tree species, which drives substantial differences in tree species composition among forest types and affects the food resources available to birds. In this case, most trees in mixed-evergreen forests produce fleshy fruits that are important in the diet of E. albiceps and other bird species. Therefore, in geographical regions with a high alpha and beta tree diversity, restoration thinnings in secondary forests should explicitly target tree composition, which appears to be at least as important as vegetation structure in determining short-term avian responses.

Kết cấu và đa dạng loài cây gỗ của rừng Dầu trên những loại đất khác nhau tại khu vực Nam Cát Tiên, tỉnh Đồng Nai

This paper introduces some characteristics of Dipterocarp forests on different soil types in Nam Cat Tien area, Dong Nai province, Vietnam. The objective of the study was to determine the differences in tree species composition and tree species diversity of Dipterocarp forest on dark brown soil developed from basalt and yellowish red soil developed from clay rock. Tree species composition and diversity of Dipterocarp forests on each soil type was analyzed from three typical sample plots with the size of 0.25 ha. All trees with diameter at breast height (DBH) from 6 cm are listed according to species, DBH, height, basal area and volume. Then determine and compare tree species composition and diversity indicators of Dipterocarp forests on two soil types. Research results have shown that the number of tree species found in Dipterocarp forests on both soil types is 65 species belonging to 54 genera of 31 families; of which the number of families in Dipterocarp forests on dark brown soil (30 families) was more than that of yellowish red soil (25 families). Dipterocarpaceae family is the dominant ecological family; of which Dipterocarpus alatus is dominant species on dark brown soil, while Anisoptera costata is dominant species on yellowish red soil. The number of tree species found in Dipterocarp forests on dark brown soil (58 species) was higher than that of yellowish red soil (47 species). The similarity coefficient for tree species on these two types of soils is 76.2%. The mixed index of Dipterocarp forests on dark brown soil (0.21) was higher than that of yellowish red soil (0.17). The tree species diversity of Dipterocarp forests on soil dark brown soil is higher than the yellowish red soil. The number of precious tree species found on these two soils is 14 species. The number of rare tree species in Dipterocarp forests on dark brown soil (31 species) was higher than that of yellowish red soil (15 species).

Leaf litter inputs reinforce islands of nitrogen fertility in a lowland tropical forest

The role of lowland tropical forest tree communities in shaping soil nutrient cycling has been challenging to elucidate in the face of high species diversity. Previously, we showed that differences in tree species composition and canopy foliar nitrogen (N) concentrations correlated with differences in soil N availability in a mature Costa Rican rainforest. Here, we investigate potential mechanisms explaining this correlation. We used imaging spectroscopy to identify study plots containing 10–20 canopy trees with either high or low mean canopy N relative to the landscape mean. Plots were restricted to an uplifted terrace with relatively uniform parent material and climate. In order to assess whether canopy and soil N could be linked by litterfall inputs, we tracked litter production in the plots and measured rates of litter decay and the carbon and N content of leaf litter and leaf litter leachate. We also compared the abundance of putative N fixing trees and rates of free-living N fixation as well as soil pH, texture, cation exchange capacity, and topographic curvature to assess whether biological N fixation and/or soil properties could account for differences in soil N that were, in turn, imprinted on the canopy. We found no evidence of differences in legume communities, free-living N fixation, or abiotic properties. However, soils beneath high canopy N assemblages received ~ 60% more N via leaf litterfall due to variability in litter N content between plot types. The correlation of N in canopy leaves, leaf litter, and soil suggests that, under similar abiotic conditions, litterfall-mediated feedbacks can help maintain soil N differences among tropical tree assemblages in this diverse tropical forest.

Heterogeneity of tree diversity and carbon stocks in Amazonian oil palm landscapes

ABSTRACTBackground: Quantitative effects of large-scale oil palm expansion in the Neotropics on biodiversity and carbon stocks are still poorly documented.Aims: We evaluated differences in tree species composition and richness, and above-ground carbon stocks among dominant land cover types in Pará state, Brazil.Methods: We quantified tree species composition and richness and above-ground carbon stock in stands in remnant primary rain forest, young secondary forest, oil palm plantation and pastures.Results: We sampled 5,696 trees with a DBH ≥ 2 cm, of 413 species in 68 families, of which 381 species were recorded in primary forest fragments. We found significant differences in species richness and carbon stock among the four land cover classes. Carbon stocks in remnant primary forest were typically over 190 Mg ha−1, while those in other land cover types were typically less than 60 Mg ha−1.Conclusion: Oil palm plantations have a species-poor tree community given active management; old plantations have a standing carbon stock which is comparable to that of secondary forest and far greater than that of pastures. Private forest reserves within oil palm company holdings play an important role in preserving primary forest tree diversity in human-modified landscapes in Amazonia.

Four decades of the coexistence of beech and spruce in a Central European old-growth forest. Which succeeds on what soils and why?

The dynamics of forests dominated by European beech (Fagus sylvatica) and Norway spruce (Picea abies) have been studied intensively. However, mainly due to a lack of long-term data, little is known about how these dynamics interact with soil conditions. In an old-growth spruce-beech forest with high soil diversity we studied how the development of tree populations differs among different soils. Data from tree censuses carried out in 1972, 1996 and 2010 in the Boubin Primeval Forest in the Czech Republic were combined with detailed soil sampling to assess the relative abundance of beech and spruce and the role of the main drivers of population dynamics (tree growth, mortality and recruitment) in changes with respect to soils. The spatial distribution of populations of the two species primarily reflected a gradient of soil hydromorphism, with beech dominating drier soils and spruce dominating wetter soils. Over the 38 years, beech expanded on all major soils, yet the most important drivers differed. The only driver acting in favour of spruce on certain terrestrial soils was its faster radial growth. However, the effect was weaker than the effect of drivers that prioritized beech, mainly tree mortality. Fine-scale mortality (deaths of individual trees) was more significant on terrestrial soils, while the effect of coarse-scale mortality (deaths from a single severe windstorm event) increased towards hydromorphic soils. Certain soils (Histosols and Albic Podzols) diverged from the general trends because of their different disturbance regimes and specific tree–soil interactions. Soils play an important role in the dynamics of an old-growth spruce-beech forest. Their physical and chemical properties together with specific disturbance regimes determine fine-scale differences in tree species composition. At the same time, soils themselves are affected by trees, e.g. through acidification. The current expansion of beech is expected to continue on terrestrial soils but will probably slow down with increasing soil wetness.

How to Calibrate Historical Aerial Photographs: A Change Analysis of Naturally Dynamic Boreal Forest Landscapes

Time series of repeat aerial photographs currently span decades in many regions. However, the lack of calibration data limits their use in forest change analysis. We propose an approach where we combine repeat aerial photography, tree-ring reconstructions, and Bayesian inference to study changes in forests. Using stereopairs of aerial photographs from five boreal forest landscapes, we visually interpreted canopy cover in contiguous 0.1-ha cells at three time points during 1959–2011. We used tree-ring measurements to produce calibration data for the interpretation, and to quantify the bias and error associated with the interpretation. Then, we discerned credible canopy cover changes from the interpretation error noise using Bayesian inference. We underestimated canopy cover using the historical low-quality photographs, and overestimated it using the recent high-quality photographs. Further, due to differences in tree species composition and canopy cover in the cells, the interpretation bias varied between the landscapes. In addition, the random interpretation error varied between and within the landscapes. Due to the varying bias and error, the magnitude of credibly detectable canopy cover change in the 0.1-ha cells depended on the studied time interval and landscape, ranging from −10 to −18 percentage points (decrease), and from +10 to +19 percentage points (increase). Hence, changes occurring at stand scales were detectable, but smaller scale changes could not be separated from the error noise. Besides the abrupt changes, also slow continuous canopy cover changes could be detected with the proposed approach. Given the wide availability of historical aerial photographs, the proposed approach can be applied for forest change analysis in biomes where tree-rings form, while accounting for the bias and error in aerial photo interpretation.

An innovative approach to disentangling the effect of management and environment on tree cover and density of protected areas in African savanna

In protected areas of the African savanna tree cover, structure and species composition are influenced by a combination of many different variables. These include complex and multi-scaled interplay of environmental factors such as water and nutrient availability, fire, herbivory and, when occurring, direct human disturbance. In this study, we conducted a comprehensive and comparative analysis of the spatial variability of tree cover and density in three neighboring Southern African National Parks (Kruger, Limpopo, and Gonarezhou) characterized by similar environmental conditions but different management plans. We sampled 3382 plots of 0.5 ha across the three parks using an innovative methodology defined as augmented visual interpretation, based on a free and open source software. This software, named Collect Earth, allows access to very high spatial and temporal resolution imagery archives. Spatial variability of tree cover and density was analyzed comparing the three parks and the two bioclimatic regions (semiarid and dry subhumid) characterizing them. The effect of relevant environmental variables such as edaphic factors, precipitation and fire frequency was also assessed. Kruger National Park is characterized by the lowest values of tree cover and density among the three Parks. Contrary to what was expected and the general trend of Southern Africa, the dry subhumid zone showed lower values of tree cover and density than the semiarid zone. Such variability is hypothesized to be related to the different managements of the three parks within the general environmental template characterizing the African savanna as well as differences in tree species composition between the two climatic zones.

Comparing forest structure and biodiversity on private and public land: secondary tropical dry forests in Costa Rica

AbstractSecondary forests constitute a substantial proportion of tropical forestlands. These forests occur on both public and private lands and different underlying environmental variables and management regimes may affect post‐abandonment successional processes and resultant forest structure and biodiversity. We examined whether differences in ownership led to differences in forest structure, tree diversity, and tree species composition across a gradient of soil fertility and forest age. We collected soil samples and surveyed all trees in 82 public and 66 private 0.1‐ha forest plots arrayed across forest age and soil gradients in Guanacaste, Costa Rica. We found that soil fertility appeared to drive the spatial structure of public vs. private ownership; public conservation lands appeared to be non‐randomly located on areas of lower soil fertility. On private lands, areas of crops/pasture appeared to be non‐randomly located on higher soil fertility areas while forests occupied areas of lower soil fertility. We found that forest structure and tree species diversity did not differ significantly between public and private ownership. However, public and private forests differed in tree species composition: 11 percent were more prevalent in public forest and 7 percent were more prevalent in private forest. Swietenia macrophylla, Cedrela odorata, and Astronium graveolens were more prevalent in public forests likely because public forests provide stronger protection for these highly prized timber species. Guazuma ulmifolia was the most abundant tree in private forests likely because this species is widely consumed and dispersed by cattle. Furthermore, some compositional differences appear to result from soil fertility differences due to non‐random placement of public and private land holdings with respect to soil fertility. Land ownership creates a distinctive species composition signature that is likely the result of differences in soil fertility and management between the ownership types. Both biophysical and social variables should be considered to advance understanding of tropical secondary forest structure and biodiversity.

Tree composition and abundance patterns differ in two watersheds of Forest Park, a large Pacific Northwest urban forest

We compared differences in patterns of tree species composition and abundance in a set of six permanent research plots designated in paired watersheds in a large forested park in Portland, Oregon: one proximal to the urban area and the other proximal to rural areas. All were established in mixed conifer-deciduous stands with similar tree age classes, orientation, topography and other environmental variables. One old-growth plot reference was included in each watershed. The urban plots have experienced periodic disturbances and are continually subjected to continual low-impact disturbances. The urban plots, in contrast to rural plots and to their reference old-growth plots, showed significant differences in tree species composition and ages, sapling numbers, and amount of coarse woody debris. NMDS and nonparametric ANOVA revealed the urban plots as having the greatest ecological distance from all other plots. Soil disturbance, lack of O- and A-horizons, and coarse woody debris were disturbance indicators. Given current patterns of regeneration, the urban plots will be dominated in the future by hardwood species. This projection, when compared with the proximate old-growth patch and with historical records for the urban end of the park, has no historic antecedent. These conclusions are concurrent with findings for other urban forests, where early successional species dominate over long periods of time. The described ecological trends, especially with the domination of invasive species, reflect the urban condition of the forest and constitute a novel state.

Patterns of urban forest composition in Utah’s growing mountain communities

Urban forests provide critical ecosystem services in cities of the Western United States, including regulating thermal extremes, supporting biological diversity, and providing cultural and recreational services. However, these services may come with trade-offs such as heavy water demand in arid environments. Thus, afforestation and its effect on the water budget – as well as other ecosystem services – can be contingent on the species composition of urban forests. Choice of tree species, in turn, is influenced by historical contingencies and development context. The objective of this study was to identify differences in tree species composition between four broad classes of urban development in Heber Valley, Utah, with classes defined by establishment age, lot size, and location within the urban-suburban environment. Publicly available information was used to categorize residential and commercial areas, and standard forestry techniques were used to collect data on trees in a stratified random survey of lots in each category. Older, established housing had the highest tree basal area and species richness per hectare, and exurban (rural, dispersed housing) developments had significantly higher species diversity than new tract housing. Because it appears that exurban communities are being replaced by tract housing, there is evidence that tree diversity may be lost. Another important aspect of community structure in urban forests is the ratio of conifers to broadleaf trees because of fundamental differences in water use patterns. Conifers were twenty-five percent of the average lot basal area in exurban and thirty-five percent in established neighborhoods, as opposed to five percent in tract housing. If functional groups are used as predictors of water use in irrigated urban systems, water demand is likely to increase with the expansion of low-diversity, angiosperm dominated tract forests in the Western US in the coming decades.

Tree community reassembly after selective and clear-cut logging in an Afro-tropical rainforest

Understanding the process of community reassembly is crucial for the conservation of biodiversity and rehabilitation of ecosystems. This study tested whether tree communities in logged forests follow an equilibrium (deterministic) or non-equilibrium (stochastic) model of succession. We assessed reassembly of tree communities in different size classes along a successional gradient consisting of nine differently aged successional forests, namely, four regenerating former clear-cuts (9–19 years), three selectively logged (42–43 years) and two primary forests (PFs) in Kibale National Park, Uganda. The results show that the forests are converging and undergoing reassembly towards PFs. The species composition of seedlings, saplings and poles declined in similarity to the PF with age but that of mature trees in the different successional stages increased towards the PFs. These differences in tree species composition among the different size classes might be due to dominance of some particular species. Recovery of tree species density, diversity and dominance in all the size classes showed directional patterns as predicted by the deterministic model of succession. Compared to other variables, tree species density and diversity in selectively logged forests recovered relatively faster and was equivalent to or higher than that of PFs at 43 years. The results of the present study indicate that community reassembly in smaller sized trees followed a stochastic model of succession. However, as trees matured, they conform to the deterministic model of succession.

Fire evolution split by continent

Boreal forest fires tend to be more intense and lethal in North America than Eurasia. Differences in tree species composition explain these differences in fire regime, and lead to contrasting feedbacks to climate.

Soil nutrients and microbial biomass in three contrasting Mediterranean forests

The extent to which the spatial and temporal patterns of soil microbial and available nutrient pools hold across different Mediterranean forest types is unclear impeding the generalization needed to consolidate our understanding on Mediterranean ecosystems functioning. We explored the response of soil microbial, total, organic and inorganic extractable nutrient pools (C, N and P) to common sources of variability, namely habitat (tree cover), soil depth and season (summer drought), in three contrasting Mediterranean forest types: a Quercus ilex open woodland, a mixed Q. suber and Q. canariensis woodland and a Pinus sylvestris forest. Soil microbial and available nutrient pools were larger beneath tree cover than in open areas in both oak woodlands whereas the opposite trend was found in the pine forest. The greatest differences in soil properties between habitat types were found in the open woodland. Season (drought effect) was the main driver of variability in the pine forest and was related to a loss of microbial nutrients (up to 75 % loss of Nmic and Pmic) and an increase in microbial ratios (Cmic/Nmic, Cmic/Pmic) from Spring to Summer in all sites. Nutrient pools consistently decreased with soil depth, with microbial C, N and P in the top soil being up to 208 %, 215 % and 274 % larger than in the deeper soil respectively. Similar patterns of variation emerged in relation to season and soil depth across the three forest types whereas the direction and magnitude of the habitat (tree cover) effect was site-dependent, possibly related to the differences in tree species composition and forest structure, and thus in the quality and distribution of the litter input.

Long-term recovery of forest structure and composition after harvesting in the coastal temperate rainforests of northern British Columbia

We examined young harvested (41–100) and naturally disturbed mature (101–250), and old (>250) temperate rainforests on the central and north coast of British Columbia to quantify the recovery rates of tree size, density, and species composition of young harvested stands towards old-growth condition. Significant variations in recovery rates were noted due to differences in site productivity. Nonmetric multidimensional scaling (NMS) ordinations, Multi-response Permutation Procedure (MRPP) summary statistics, and Sorensen’s similarity coefficients (SC) all indicate moderate levels of similarity between young and old stands. Rich sites show greater similarity between young and old forests (SC=55%) than do medium sites (SC=41%), indicating more rapid recovery. Differences in tree species composition, especially for western redcedar, were apparent among young and older forests on all sites. We believe that proactive management is required to ensure that western redcedar, an ecologically, culturally, and economically valuable tree species, is maintained as a significant component in the managed second-growth forests of central and north coast British Columbia. Our results indicate that second-growth forests, while not as structurally developed as old-growth, are developing some ecologically important structural characteristics at relatively young ages (80–100years) and as such, contribute towards ecological integrity and biodiversity of the coastal temperate rainforest landscape.