Understory Strata Research Articles

Changes in Vertical Stratification of Neotropical Nymphalid Butterflies at Forest Edges Are Not Directly Caused by Light and Temperature Conditions

Habitat fragmentation and land use changes threaten neotropical habitats and alter patterns of diversity at forest edges. Like other arthropod assemblages, neotropical fruit-feeding butterfly communities show strong vertical stratification within forests, with some recent work showing its potential role in speciation. At forest edges, species considered to be forest canopy specialists have been observed descending to the forest understory, with the similarity in light conditions between the canopy and understory strata at edges hypothesized to be responsible for this phenomenon. We conducted a study using standardized sampling to document and quantify this edge effect, characterize edge and forest strata, and estimate the relative contributions of temperature and light conditions to changes in nymphalid butterfly stratification at forest edges. We found strong evidence of an edge effect in these butterflies and confirmed strong differences in light and temperature, showing that the edge understory differs little from forest canopy conditions. Of 41 species common to both forests and edges, 28 shifted to have a lower canopy probability at the edge, and our model detected a decrease in canopy probability of 0.165. Furthermore, our analysis indicated the relative abundance of canopy taxa increased at the edge, and the tribes Haeterini and Morphini were especially sensitive to edge effects. However, the analyses here did not clearly implicate temperature or light magnitude in causing changes in neotropical nymphalid vertical stratification at forest edges. Instead, our results point to other mediator variables as being important for changes at tropical forest edges. From our data, edge-responsive species can be separated into two different categories, which likely relates to their resilience to anthropogenic disturbance. We also note that structural causal models have a potential place in future work on tropical conservation, given they can provide causal estimates with observational data.

A Century of Change in a Mature Urban Forest: the Thain Family Forest of the New York Botanical Garden, Bronx, New York

Abstract Urban forests have long been understudied, resulting in a scarcity of long-term data to guide future management. The New York Botanical Garden in New York City has been stewarding the 20 ha Thain Family Forest since 1895. Using inventory data between 1937 and 2021, we document how structure, diversity, and composition of the forest have changed over the past century. Our results show an increase in the proportion and diversity of hardwood species, including oaks, hickories, red maple, black cherry, and American beech, following the loss of a dominant species, eastern hemlock. Despite changes in composition, we find no significant differences in the mean basal area, density, and tree diameter of canopy trees (diameter at breast height [DBH] ≥ 15 cm) from 1937 to 2021. Assessments of small diameter stems (DBH ≥ 2.54 cm) show increasing density, decreasing diameter, and increasing richness from 1985 to 2021, suggesting a period of understory recruitment/regeneration. During this time, native species have been dominant in both overstory and understory strata. These observations mirror trends recorded in hemlock–hardwood and oak–hickory forests region-wide, indicating that, with continued conservation and active management, urban and rural forests may develop in similar patterns and encouraging regional approaches to forest management. Study Implications: Urban forests have long been understudied, resulting in a scarcity of long-term data to guide future management. Over the past century, the 20 ha Thain Family Forest in New York City has experienced a significant change in species composition, with an increase in the proportion and diversity of hardwood species following the loss of eastern hemlock. Despite these changes, forest canopy structure has remained stable. These observations mirror those observed in hemlock–hardwood and oak–hickory forests regionwide, suggesting that with continued conservation and active management, urban and rural forests may develop in similar patterns. The results of this study support continued investment in the research and management of urban forests as a comprehensive part of regional forest management efforts.

Arthropod-based biotic integrity indices: A novel tool for evaluating the ecological condition of native forests in the Azores archipelago

Island ecosystems are experiencing a significant decline in biodiversity, with forest biodiversity being particularly affected by several biodiversity erosion drivers. This alarming situation highlights the urgent need for conservation managers to develop more accurate and efficient tools to assess and monitor the quality status of sites. To address this issue, our study focuses on the development of two biological integrity indices (IBI) that utilize arthropod communities as indicators to measure the quality of forest sites. In accordance with studies that showed stratification of species diversity, we developed an IBI for canopy stratum (IBI-Canopy) and an IBI for an intermediate stratum targeting the forest understory (IBI-SLAM). We calibrated both indices on seven parameters for comparison purpose with a previous developed epigean IBI. Percentages of endemic, native non-endemic and introduced species richness and abundance were included in both indices. Percentages of Diplopoda species richness and abundance were included in IBI-Canopy and percentages of Saprophagous species richness and abundance were included in IBI-SLAM. As expected species richness and abundance of endemic species were negatively related to disturbance and selected for both IBI. Surprisingly, species richness and abundance of native non-endemic species were positively related to disturbance. The study highlights the limitations of single measurements in detecting all types of pressure sources, and proposes a multi-measurement system to provide a more comprehensive understanding of the overall system conditions. Our efficient and accessible indices confirmed low preservation status in Flores Island compared to Terceira and Pico, consistent with prior empirical studies. Our analyses also showed that canopy detect disturbance earlier than intermediate understory stratum. Our methodology has successfully been developed and tailored to the unique arthropod communities found in the Azores forests. While it may not be suitable for random forest sites, it can serve as a valuable source of inspiration for the development of arthropod-based IBIs in other islands of the world for which standardized endemic and exotic species richness and abundance could be obtained. The study also showed that arthropod assemblages mimicked forest biodiversity stratification and this is reflected in differences expressed by the IBIs.

Drivers of aboveground biomass shift with forest stratum in temperate forest of North China

A better understanding of the underlying ecological mechanisms of diversity-biomass relationships in forest layers (i.e., overstory and understory) is critical to understand the importance of vertical stratification to the functioning of forest ecosystems. However, it is not clear how multiple abiotic (i.e., climate and geography) and biological (i.e., biodiversity, functional characteristics, and stand structural complexity) factors simultaneously determine the aboveground biomass (AGB) of each individual forest stratum. We used data on 156,270 trees from 1986 plots in North China to explore the relationships among biological diversity, plant functional traits, stand structure, climate and topography on variation in AGB of each stratum. The results showed that different biological factors determined the AGB of overstory and understory, and thus indicating different underlying ecological mechanisms in temperate forests. The effects of forest biodiversity on AGB were only significant in understory stratum. In the overstory of the forest, forests with high tree-size dimension inequality and high dominant tree height had larger AGB, hence mass ratio effect and stand structure complexity were the main ecological mechanisms for high biomass. In understory, diversity and overstory attributes were the main factors affecting biomass. Tree height and AGB of the overstory reduced the AGB of the understory layer. In consequence overstory attributes and niche complementation were the main ecological mechanisms in the understory. The overstory exerted influence on the understory through resource quantity and resource heterogeneity. Our findings have important implications for carbon management, enhancement of forest functions and sustainable forest management in temperate forests.

The Herbaceous Understory Plant Community in the Context of the Overstory: An Overlooked Component of Tropical Diversity

Lowland tropical rainforests harbor the most diverse plant communities in the world, but the herbaceous plants of the understory are often overlooked. To address this knowledge gap, we asked to what extent the understory herbaceous community contributes to the species richness and phylogenetic diversity of plant communities by surveying a neotropical rainforest at Los Tuxtlas, Mexico. We used Gentry transects to characterize the woody overstory community, and line-intercepts within the same transects to survey understory herbs and subshrubs. We also used published phylogenies to calculate community phylogenetic diversity with and without the understory stratum. We found that the understory contained a diverse (23 species, or 22.1% of all species surveyed) and phylogenetically distinct plant community dominated by aroids (13 species) and ferns (4 species). Inclusion of the understory stratum increased total species richness by 28.4% but increased phylogenetic diversity by 41.4%. Additionally, in contrast to temperate forests, the understory plant community was much less diverse than the overstory, which contained 81 species > 1 cm dbh (77.9% of all species surveyed). This survey adds to the hitherto small body of literature comparing understory and overstory strata in tropical rainforests and reveals previously overlooked patterns of floristic diversity.

Vegetation Pattern and Regeneration Dynamics of the Progressively Declining Monotheca buxifolia Forests in Pakistan: Implications for Conservation

Monotheca buxifolia (Falc.) A. DC., a wild edible fruit-yielding tree species, has economic and ecological importance, yet there is a lack of studies concerning its distribution pattern and regeneration dynamics at a larger-scale. This study aims to produce the first country-level classification of Monotheca forests based on their unique floristic composition and influential abiotic factors, besides their natural regeneration dynamics, across the environmentally diverse landscapes in Pakistan. For this purpose, floristic inventory was carried out in 440 plots where environmental variables, stand dendrometric characteristics and woody-species regeneration were recorded. During this survey, 3789 individuals of 27 woody tree species belonging to 25 genera and 22 families were sampled. These native and exotic tree species were mostly dicot (73%) with predominately mega-phanerophytic (88%) lifeforms, which largely reflect strong chorological differentiation and distinct linkage (55%) to the Sino-Japanese phytogeographical region. M. buxifolia and co-occurring species exhibiting similar environmental affinities were grouped into four ecologically distinct communities by Ward’s cluster analysis. Ordinations further highlight the special effects of topographic and edaphic factors besides anthropogenic interference on the sampled plots. Generally, Monotheca stands were moderately dense, with the average density varying considerably, ranging from 296 to 325 individuals/ha, with basal area ranging from 41.26 to 93.35 m2 ha−1. In the understory stratum, natural regeneration of Monotheca was mostly scant and mainly covered by Dodonaea shrubs. Size class structure of the dominant species shows pronounced effect of anthropogenic intervention as reflected by the presence of fewer individuals of juveniles and larger trees. Overall, the cut stump frequency was higher at juvenile and mature stages, which may be attributed to over-harvesting and extraction of fuelwood apart from the adverse effect of climate change in the region. We concluded that both topographic and edaphic factors coupled with biotic interventions are more influential in the distribution and persistence of M. buxifolia and co-occurring woody species and might be considered in its restoration and conservation. Thus, we recommend an urgent management plan to favor Monotheca regeneration for allowing the renewal of these rapidly declining remnant stands in Pakistan.

Strata-dependent relationships among temperate forest structure, diversity, and growth rate along a local-scale environmental gradient

Exploring diversity-function relationships across overstory and understory strata is crucial for understanding ecological mechanisms, biodiversity conservation and forest management. In this study, we aimed to investigate the relationships among species diversity and stand structure, environmental factors, leaf area index (LAI), and the growth rate of overstory and understory strata in a mixed-broadleaf Korean Pine Forest in Northeast China. We performed structural equation models (SEMs) to evaluate the effects of environmental factors on overstory and understory species diversity, stand structure, and growth rate; the effects of overstory and understory species diversity and stand structure (total basal area, stem density, and diameter at the breast height variation) on the LAI and their respective growth rates; and the effect of overstory stratum on understory stratum species diversity, stand structure, and growth rate. Our results showed that species diversity determined the growth rate for overstory strata, while stem density was appropriate to determine understory growth rate. The integrative SEM accounted for 13, 13, 11, 8, and 7% of the variance in overstory species diversity, understory absolute growth rate, overstory absolute growth rate, understory stem density, and LAI, respectively. The diversity of overstory species had a positive direct influence on overstory growth but a negative direct effect on understory growth. Environmental factors (i.e., soil nutrients and soil moisture) positively influenced the understory growth rate but negatively influenced the overstory growth rate. Increasing understory stem density may increase the LAI; simultaneously, the LAI supported the understory growth rate. In natural forests, an arrangement between the overstory canopy and the availability of environmental resources is ideal for controlling species diversity and maximizing the productivity of both the overstory and understory strata.

Species Diversity, Growing Stock Variables and Carbon Mitigation Potential in the Phytocoenosis of Monotheca buxifolia Forests along Altitudinal Gradient across Pakistan

The sub-tropical broadleaved forests in Pakistan are the main constituents of the ecosystem services playing a vital role in the global carbon cycle. Monotheca buxifolia (Falc.) A. DC. is an important constituent of these forests, encompassing a variety of ecological and commercial uses. To our best knowledge, no quantitative studies have been conducted in these forests across the landscape to establish a baseline for future monitoring. We investigated the forest structural attributes, growing stock characteristics and total biomass carbon stock and established relationships among them in the phytocoenosis of Monotheca forests along an altitudinal gradient in Pakistan to expand an eco-systemic model for assessment of the originally-implemented conservation strategies. A floristic survey recorded 4986 individuals of 27 species in overstory and 59 species in the understory stratum. Species richness (ANOVA; F = 3.239; p = 0.045) and Simpson’s diversity (ANOVA; F = 2.802; p = 0.043) differed significantly in three altitudinal zones, with a maximum value for lower elevations, followed by middle and higher elevations. Based on the importance values, Acacia modesta and Olea ferruginea are strong companions of M. buxifolia at lower and higher altitudes, whereas forests at mid elevation represent pure crop of M. buxifolia (IVI = ≥85.85%). A similar pattern in stem density, volume and Basal area were also recorded. The carbon stock in trees stratum (51.81 T ha−1) and understory vegetation (0.148 T ha−1) contributes high values in the lower elevation forests. In contrast, soil carbon had maximum values at higher elevation (36.21 T ha−1) and minimum at lower elevation (16.69 T ha−1) zones. Aboveground biomass carbon stock (AGB BMC) of woody trees, understory vegetation and soil organic carbon (SOC) were estimated higher (77.72 T ha−1) at higher and lower (68.65 T ha−1) elevations. Likewise, the AGB BMC exhibited a significant (p < 0.05) negative correlation with elevation and positive correlation with soil carbon. We concluded that lower elevation forests are more diverse and floristically rich in comparison to higher altitudinal forests. Similarly, the biomass carbon of Monotheca forests were recorded maximum at low altitudes followed by high and middle ranges, respectively.

Pre-fire aboveground biomass, estimated from LiDAR, spectral and field inventory data, as a major driver of burn severity in maritime pine (Pinus pinaster) ecosystems

The characterization of surface and canopy fuel loadings in fire-prone pine ecosystems is critical for understanding fire behavior and anticipating the most harmful ecological effects of fire. Nevertheless, the joint consideration of both overstory and understory strata in burn severity assessments is often dismissed. The aim of this work was to assess the role of total, overstory and understory pre-fire aboveground biomass (AGB), estimated by means of airborne Light Detection and Ranging (LiDAR) and Landsat data, as drivers of burn severity in a megafire occurred in a pine ecosystem dominated by Pinus pinaster Ait. in the western Mediterranean Basin. Total and overstory AGB were more accurately estimated ( R 2 equal to 0.72 and 0.68, respectively) from LiDAR and spectral data than understory AGB ( R 2 ​= ​0.26). Density and height percentile LiDAR metrics for several strata were found to be important predictors of AGB. Burn severity responded markedly and non-linearly to total ( R 2 ​= ​0.60) and overstory ( R 2 ​= ​0.53) AGB, whereas the relationship with understory AGB was weaker ( R 2 ​= ​0.21). Nevertheless, the overstory plus understory AGB contribution led to the highest ability to predict burn severity (RMSE ​= ​122.46 in dNBR scale), instead of the joint consideration as total AGB (RMSE ​= ​158.41). This study novelty evaluated the potential of pre-fire AGB, as a vegetation biophysical property derived from LiDAR, spectral and field plot inventory data, for predicting burn severity, separating the contribution of the fuel loads in the understory and overstory strata in Pinus pinaster stands. The evidenced relationships between burn severity and pre-fire AGB distribution in Pinus pinaster stands would allow the implementation of threshold criteria to support decision making in fuel treatments designed to minimize crown fire hazard.

The hidden side of diversity: Effects of imperfect detection on multiple dimensions of biodiversity.

Studies on ecological communities often address patterns of species distribution and abundance, but few consider uncertainty in counts of both species and individuals when computing diversity measures.We evaluated the extent to which imperfect detection may influence patterns of taxonomic, functional, and phylogenetic diversity in ecological communities.We estimated the true abundance of fruit‐feeding butterflies sampled in canopy and understory strata in a subtropical forest. We compared the diversity values calculated by observed and estimated abundance data through the hidden diversity framework. This framework evaluates the deviation of observed diversity when compared with diversities derived from estimated true abundances and whether such deviation represents a bias or a noise in the observed diversity pattern.The hidden diversity values differed between strata for all diversity measures, except for functional richness. The taxonomic measure was the only one where we observed an inversion of the most diverse stratum when imperfect detection was included. Regarding phylogenetic and functional measures, the strata showed distinct responses to imperfect detection, despite the tendency to overestimate observed diversity. While the understory showed noise for the phylogenetic measure, since the observed pattern was maintained, the canopy had biased diversity for the functional metric. This bias occurred since no significant differences were found between strata for observed diversity, but rather for estimated diversity, with the canopy being more clustered.We demonstrate that ignore imperfect detection may lead to unrealistic estimates of diversity and hence to erroneous interpretations of patterns and processes that structure biological communities. For fruit‐feeding butterflies, according to their phylogenetic position or functional traits, the undetected individuals triggered different responses in the relationship of the diversity measures to the environmental factor. This highlights the importance to evaluate and include the uncertainty in species detectability before calculating biodiversity measures to describe communities.

Overstory and niche attributes drive understory biomass production in three types of subtropical plantations

Understory vegetation plays a very important role in maintaining biodiversity, soil nutrient cycling and carbon stocks, yet biomass productivity at the understory layer has been largely overlooked in previous studies. Our study provides one of the most comprehensive tests of how niche attributes, soil fertility and canopy attributes shape understory biomass in a forest restoration context. We investigated the relative effects on understory biomass of five categories of ecological variables related to five hypotheses – i) niche complementarity: functional diversity indices of understory plants, ii) mass ratio: community weighted mean (CWM) traits of understory plants, iii) overstory attributes: planted tree diameter, basal area, height, canopy cover and stem density, iv) soil nutrients: soil pH and soil C, N, P, and v) plantation type (an exotic broad-leaved monoculture, a native broad-leaved monoculture and a native conifer mix). Here, understory biomass was studied at two understory layers: high (2 to 7 m above ground) and low (less than 2 m above ground) in the plantations of subtropical area of Southern China. We surveyed vegetation, measured soil nutrients and determined five important leaf functional traits for each species. Multiple linear regression models were performed to select the best models and to assess the statistical significance of the effects of each variable. Our results showed that the best models for predicting biomass in the high (mean = 603.29 g m−2) and low (mean = 596.81 g m−2) layers were, respectively, the models for canopy cover and functional richness (FRic) interacting with plantation type. Model analyses showed a positive relationship between canopy cover and high-layer biomass (P < 0.001 and P < 0.05 respectively in native mixed-conifer and broad-leaved plantations) and between FRic and low-layer biomass (P < 0.001 in both native mixed-conifer and broad-leaved plantations) in the two native plantations. A positive relationship was also found between the CWM of leaf dry matter content and biomass in the high understory layer in the native mixed-conifer plantation (P < 0.001). Meanwhile, soil N was negatively correlated with low layer biomass (P < 0.01). Our study highlighted the dominant role of overstory attributes and niche complementarity in explaining forest understory productivity compared to other hypotheses. The effects of ecological factors on understory biomass varied in direction and magnitude, depending on understory stratum and plantation type. Indeed, the mechanisms behind biomass production in the high and low understory layers appeared to be decoupled. The typical biodiversity-ecosystem functioning relationship only drove low-layer biomass, while high-layer biomass was influenced by canopy cover.

Tree species composition and selection effects drive overstory and understory productivity in reforested oil sands mining sites

AbstractReforestation is a feasible option for the eventual restoration of biodiversity and ecosystem services on deforested oil‐sands mining sites. The associations between plant diversity and productivity spanning the different strata of restoration forests, in conjunction with specific factors that may impact these relationships, remain uncertain. We sampled 94 sites that encompassed conifer, mixed‐wood, and broadleaved overstory types as three exemplar substrates following the reforestation of oil‐sands mining sites in Alberta, Canada. We employed structural equation modeling to investigate the correlations between species diversity and aboveground biomass production spanning forest vegetation strata, while concurrently accounting for the effects of overstory composition, functional diversity/identity, soil fertility, and restoration age. We found that the relationships between species diversity and biomass were negative, or inconsequential across restoration forest strata. Overstory biomass was linked to the coniferous tree proportion and community‐weighted mean of leaf nitrogen, rather than the species and functional diversity of overstory trees. Further, overstory composition, diversity, and biomass were the key features involved in the diversity and biomass of understory strata. Our results demonstrated the importance of overstory tree species composition and selection effects toward driving overstory and understory productivity in restoration forests at post‐oil sands mining sites. Coniferous trees were observed to have lower leaf nutrient levels and negative impacts on the productivity and diversity of overstory and shrub layers. Therefore, it was recommended that a greater proportion of broadleaved trees should be incorporated to promote productivity and species diversity in restoration forests through the enhancement and utilization of available resources.

Effect of algal phenology on seasonal dynamics of gammarid assemblages: differences between canopy and understory strata in a Sargassum yezoense bed

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 634:63-76 (2020) - DOI: https://doi.org/10.3354/meps13194 Effect of algal phenology on seasonal dynamics of gammarid assemblages: differences between canopy and understory strata in a Sargassum yezoense bed Masafumi Kodama1,*, Tomohiko Kawamura1, Kenta Nakamoto1, Naoya Ohtsuchi1, Jun Hayakawa1, Takayuki Kanki1, Takashi Kitagawa1, Yoshiro Watanabe2 1International Coastal Research Center, Atmosphere and Ocean Research Institute, The University of Tokyo, Akahama, Otsuchi, Iwate 028-1102, Japan 2Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8564, Japan *Corresponding author: mkodama@aori.u-tokyo.ac.jp ABSTRACT: Macroalgal beds can be vertically differentiated into canopy and understory strata, and each can exhibit different phenology in algal biomass and morphology. Thus, for epibenthic invertebrates, macroalgal beds provide both vertically and seasonally heterogenous habitats, and epibenthic assemblages can be predicted to show different patterns of seasonal dynamics reflecting the different effects of algal phenology between the canopy and understory. We described and compared the seasonal dynamics of gammarid assemblages and algal phenology in the canopy and understory of a Sargassum bed in Otsuchi Bay, Japan. Gammarid assemblages showed distinctly different seasonal dynamics in abundance and species composition between the 2 habitats. In the canopy, gammarid abundance peaked in July, which was mainly explained by fluctuations in abundance of the dominant tube-dwelling filter-feeder Jassa morinoi. In the understory, gammarid abundance peaked in August-September, clearly later than in the canopy, and was also dominated by tube-dwelling filter-feeders, but different species such as Monocorophium uenoi and Gammaropsis japonicus. These differences in assemblage dynamics of gammarids can be explained by the Sargassum defoliation in late summer, resulting in decreased habitat space and complexity for gammarids in the canopy. In the understory, however, Sargassum defoliation increased the amount of detrital deposition, providing food sources and additional habitat for gammarids. This study demonstrates that algal phenology can have strong but different effects on epibenthic invertebrates inhabiting canopy and understory strata. KEY WORDS: Gammarid · Sargassum beds · Assemblage dynamics · Algal phenology · Habitat heterogeneity · Canopy · Understory Full text in pdf format Supplementary material PreviousNextCite this article as: Kodama M, Kawamura T, Nakamoto K, Ohtsuchi N and others (2020) Effect of algal phenology on seasonal dynamics of gammarid assemblages: differences between canopy and understory strata in a Sargassum yezoense bed. Mar Ecol Prog Ser 634:63-76. https://doi.org/10.3354/meps13194 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 634. Online publication date: January 23, 2020 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2020 Inter-Research.

Shifting baselines in coastal forests: Rising seas transform plant communities from the ‘ground’ up

Increases in the rate of sea level rise are likely to result in changes to disturbance-adapted coastal forests and associated freshwater resources over the next several decades. In this study, we investigated how the press disturbance of two decades of sea level rise altered island hydrology and interacted with pulse disturbances (frequent hurricane impacts) to alter coastal forest composition and structure. The research was conducted on two low-elevation islands located within the lower Florida Keys: Big Pine and Upper Sugarloaf Keys. Groundwater salinity and vegetation structure and composition were sampled in the early 1990s prior to impact from two hurricanes – Hurricanes Georges (1998) and Wilma (2005) – and again in 2012/2013 in permanent plots inside and outside the boundaries of the islands’ freshwater lenses. Using linear mixed effects modeling, we examined whether groundwater salinity varied over time among locations, and investigated whether this variation was reflected in changes in forest structure and composition in three height strata. The results of this analysis revealed that groundwater salinity underlying plots outside the freshwater lens increased over the two decades, while salinity of groundwater at plots inside the freshwater lens remained stable. The greatest shift in composition occurred in the understory strata along a gradient of increasing salinity, and plots located outside the freshwater lens gained species typical of tidally-influenced buttonwood forest and lost glycophytic species. Viewed against the background of recurring hurricane impacts, these findings suggest that sea level rise is currently altering both groundwater resources and the composition of coastal forests in the Florida Keys. Similar dynamics should be observed in low-lying coastal forests within ocean basins subject to increased tropical cyclone activity. Management of these island coastal forests must now consider the continually shifting nature of the resource in light of acceleration in sea level rise.

Spiders (Arachnida: Araneae) of the tropical mountain cloud forest from El Triunfo Biosphere Reserve, Mexico

We carried out an intensive and systematized sampling of the spider fauna of the tropical mountain cloud forest (TMCF) in El Triunfo Biosphere Reserve, Chiapas, Mexico, in order to analyze their composition, species richness, abundance, and proportion of undescribed species, and to compare these results with those found in other TMCFs. We sampled ten plots in two seasons (dry and rainy) using different sampling techniques on two strata (ground and understory). A total of 7,432 specimens were collected corresponding to 28 families, 78 genera and 111 morphospecies. A high proportion of total species (58.6%) were undescribed species. For 11 species originally described from a single sex, we found the other sex. Five species and one genus were new records for the Mexican spider fauna. Understory stratum had higher numbers of species and individuals than ground stratum, and there was a high species turnover, with only 17% of the total species shared between strata. The spider fauna of El Triunfo shows similarities with other TMCFs (especially that on the same mountain range) concerning the identities of dominant and species-rich families, family and genera composition, the presence and relevance (in abundance or richness) of families that are uncommon in lowland tropical habitats (Linyphiidae and Theridiosomatidae), and in the high proportion of undescribed species. However, there is a high species turnover among sites (only 16% species shared), even at relatively short distances, that seems derived in part from the relative high proportions of endemic species. Our results suggest that high abundance of Theridiosomatidae and Linyphiidae, together with high species richness of this last family, could be used as conservation indicators for the Mexican TMCFs. The high numbers of undescribed species in the analyzed TMCFs, and their relatively high endemicity levels, support that TMCFs could be regarded as hotspots for the order Araneae.

Temporal Changes in Species, Phylogenetic, and Functional Diversity of Temperate Tree Communities: Insights From Assembly Patterns.

Species-based approaches to the analysis of changes in successional community assemblages are limited in the ability to reflect long-term evolutionary and functional trait responses of organisms to environment change. Recent advances in concepts and analyses of community phylogenetics and functional traits have improved the interpretation and understanding of community assembly processes. Here, we examined phylogenetic signals of four functional traits such as maximum height, leaf size, seed mass and wood density in woody plant species and temporal changes in species, phylogenetic, and functional diversity among forest strata (i.e., whole, overstory, and understory strata) at four forest long term ecological research sites in South Korea. A census of woody plant species was implemented in a 1-ha permanent plot of each study site every 5 years. We analyzed community structure and compositional turnover using twenty-five 20 × 20 m2 quadrat data converted from 1-ha plot data of each site. We found that phylogenetic signals for four functional traits were low but significant, indicating that phylogenetic diversity may be used as a crude surrogate measure of functional diversity. Temporal changes in alpha and beta components of the three diversity differed among forest strata and four study sites over time. This study also revealed that the temporal changes of phylogenetic and functional diversity for understory strata in a forest, which were consecutively damaged by typhoon, were more extreme and larger than those of understory strata in the other sites. Therefore, our study supports recent studies that plant community structures differ among forest strata and such differences of community structure among sites can be accelerated by disturbance. Although the role and relative importance of niche-based deterministic and neutral processes for the patterns of successional community structure differed among the study sites, we found niche-based deterministic processes are the dominant drivers in structuring plant community assembly regardless of forest age and disturbance in this study. From these results, our study suggests that contemporary forest ecosystems are composed of mosaics of plant communities that are formed by interactions among various processes.

Understory bird community from wildlife protected areas: diversity, seasonal variation and similarity

The bird diversity is threatened and many studies have been focusing on preservation and conservation efforts. For example, Wildlife Protected Areas are created in order to protect this diversity, however, just few areas have been created, which increases the need of private initiatives to support the environment conservation challenge. The Quedas do Rio Bonito Ecological Park is a protected area located in south of Minas Gerais state, Brazil. Herein, we present the median richness when compared to others studies in southeastern Brazil, as well as richness estimative of the understory stratum, seasonal variations and similarities among areas. Therefore, this paper presents arguments to assist future conservation studies since the knowledge on community in different areas is primordial when comparing the environment conditions in Biological Conservation projects.

Abiotic and biotic drivers of species diversity in understory layers of cold temperate coniferous forests in North China

Understory plants are important components of forest ecosystems and play a crucial role in regulating community structures, function realization, and community succession. However, little is known about how abiotic and biotic drivers affect the diversity of understory species in cold temperate coniferous forests in the semiarid climate region of North China. We hypothesized that (1) topographic factors are important environmental factors affecting the distribution and variation of understory strata, and (2) different understory strata respond differently to environmental factors; shrubs may be significantly affected by the overstory stratum, and herbs may be more affected by surface soil conditions. To test these hypotheses, we used the boosted regression tree method to analyze abiotic and biotic environmental factors that influence understory species diversity, using data from 280 subplots across 56 sites in cold temperate coniferous forests of North China. Elevation and slope aspect were the dominant and indirect abiotic drivers affecting understory species diversity, and individual tree size inequality (DBH variation) was the dominant biotic driver of understory species diversity; soil water content was the main edaphic factors affecting herb layers. Elevation, slope aspect, and DBH variation accounted for 36.4, 14.5, and 12.1%, respectively, of shrub stratum diversity. Shrub diversity decreased with elevation within the range of altitude of this study, but increased with DBH variation; shrub diversity was highest on north-oriented slopes. The strongest factor affecting herb stratum species diversity was slope aspect, accounting for 25.9% of the diversity, followed by elevation (15.7%), slope (12.2%), and soil water content (10.3%). The highest herb diversity was found on southeast-oriented slopes and the lowest on northeast-oriented slopes; herb diversity decreased with elevation and soil water content, but increased with slope. The results of the study provide a reference for scientific management and biodiversity protection in cold temperate coniferous forests of North China.

Assessing spatial dynamics of a Pinus nigra subsp. salzmannii natural stand combining point and polygon patterns analysis

This study analyzes the structure and regeneration dynamics of a Mediterranean high-altitude natural pine forest (Pinus nigra subsp. salzmannii) located in Sierra de Cazorla (Jaén, Spain). Spatial relationships among the adult tree overstory and understory strata are investigated in order to clarify the spatial dynamics of this unique forest stand. As regards the understory strata, we examine shrubs and pine recruitment separately. Both understory strata are better described by the area they occupy than by their constituent individuals. This approach invalidates using traditional spatial point pattern analysis with indicators such as the K-function, which only deal with vector data of the same dimension (points, lines or polygons). We use a recently developed approach in spatial association analysis to investigate spatial association between adult tree overstory (points) and understory strata (polygons) from both global and local spatial insights. Tree-stand overstory has been investigated regarding size and spatial tree-stand structure considering adult trees as points. The results show that the pine stand presents an irregular and uneven-aged structure of trees due to the effective and gradual recruitment of new trees over time, even if the forest cover is quite low. Spatial analysis of the overstory and understory relationship has shown a mainly attractive spatial relationship between the pine overstory and the pine regeneration understory, with seedling patches more likely to appear in the neighborhood of adult trees than away from them. In contrast, shrub patches presented a repelling location in relation with adult trees, and were less abundant near the pines than far from them. Shade intolerance of shrub species could account for this finding. The spatial relationship among shrubs and pine recruitment turned out to be clearly mutually exclusive in our study. Global and local spatial analysis using indices of point-polygon spatial assessment has proven to be a good tool to elucidate relationships among different forest stand strata.

Flexibility in positional behavior, strata use, and substrate utilization among Bale monkeys (Chlorocebus djamdjamensis) in response to habitat fragmentation and degradation.

Studies of the effects of habitat fragmentation and degradation on primate positional behavior, strata use, and substrate utilization offer valuable insights into the behavioral and ecological flexibility of primates whose habitats have undergone extensive anthropogenic disturbance. In this study, we evaluated how positional behavior, strata use, and substrate utilization differed between Bale monkeys (Chlorocebus djamdjamensis)-bamboo-eating cercopithecids endemic to the southern Ethiopian Highlands-occupying continuous versus fragmented forests. Bale monkeys in forest fragments (where bamboo had been degraded or eradicated) spent significantly more time on the ground and in understory strata whereas those in continuous forest spent significantly more time in the middle and upper strata. Bale monkeys in forest fragments also spent significantly more time walking and galloping and significantly less time climbing than those in continuous forest. Our results suggest that, unlike the primarily arboreal Bale monkeys in continuous forest, Bale monkeys in forest fragments should be characterized as semi-terrestrial. In response to habitat disturbance in fragments, we observed a greater emphasis on terrestrial foraging and travel among Bale monkeys in these human altered habitats, which may put them at greater risk of predation and conflict with nearby human populations. Bale monkeys in fragments exhibit flexibility in their positional behavioral repertoire and their degree of terrestriality is more similar to their sister taxa in Chlorocebus than to Bale monkeys in continuous forest. These findings suggest that habitat alteration may compel Bale monkeys to exhibit semi-terrestrial behaviors crucial for their persistence in human-modified habitats. Our results contribute to a growing body of literature on primate behavioral responses to anthropogenic modification of their habitats and provide information that can contribute to the design of appropriate conservation management plans.