Ecosystem Succession Research Articles

Diversity in phytoplankton communities: A field test of the intermediate disturbance hypothesis

The species dynamics is the feature of the ecosystem succession and is a key issue in the disturbance ecology. The intermediate disturbance hypothesis proposes that the highest diversity is maintained at intermediate scales of disturbance. This hypothesis has been applied to phytoplankton in water-body. It was found out that a low similarity between consecutive water samples is the result of a drastic disturbance, whereas a high similarity indicates a stable condition. To investigate whether the intermediate disturbance hypothesis is applicable to phytoplankton communities in water-body with a pollution gradient, we provided a field test in Changguangxi National Urban Wetland Park in Wuxi, China. We sampled once a month over a span of four seasons. The phytoplankton species were identified, and water quality monitoring was conducted as the disturbance factor in this study, which included the carbon, nitrogen and phosphorus concentrations. We calculated the similarities of phytoplankton species and water quality among the sampling locations and regarded them as the indicators of disturbance to study the impacts of water pollution. Our results indicated that: (1) the fitting curves of phytoplankton community diversity and similarity showed unimodal patterns over four seasons, which supported the intermediate disturbance hypothesis; (2) the response of phytoplankton diversity to water quality levels was not clear. When the water quality similarity was plotted against the phytoplankton diversity, there was no unimodal relationship, neither in the particular season nor over an entire year. We concluded that in this study the intermediate disturbance hypothesis was confirmed by the phytoplankton composition similarity, but water quality failed to be an indicator of a disturbance.

Andropogon virginicus L.

<i>Andropogon virginicus</i> L.

Is the alternative splicing factor Rbfox1 associated with aggressive behaviour in mouse models?

In this study, the spatial and seasonal bacterioplankton community dynamics were investigated in the main channel of the Middle Route of the South-to-North Water Diversion Project (MRP) using Illumina HiSeq sequencing. Water samples were collected in spring and summer from south to north at eight water quality monitoring stations, respectively. The results showed that seasonal changes had a more pronounced effect on the bacterioplankton community compositions (BCCs) than spatial variation. The diversity analysis results indicated that samples of summer have more operational taxonomic units (OTUs), higher richness and diversity than those in spring. The main phyla, Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria and Chloroflexi, displayed significant differences (P < 0.05) between spring and summer in the main channel. The Redundancy analysis (RDA) targeting all samples indicated that specific conductivity (SPC), dissolved oxygen (DO), pH and temperature (T) might be key factors in driving BCCs, while trophic status showed no significant correlation (P > 0.05). The present study provides important insights into the potential ecological roles of specific taxa in the new artificial ecosystem and it offers reference for studies on ecosystem succession of other giant interbasin water diversion project in the world.

Revealing microbial processes and nutrient limitation in soil through ecoenzymatic stoichiometry and glomalin-related soil proteins in a retreating glacier forefield

The glacial retreat is observed and predicted to increase in intensity especially in high-elevation areas as a result of global warming, which leaves behind a primary succession along soil chronosequences. Although soil microbes have been recognized as main drivers of ecological and evolutionary processes, our understanding of their effects on nutrient biogeochemistry during primary succession remains limited. In this study, we investigated changes in the microbial community structure, ecoenzymatic stoichiometry, and glomalin-related soil protein (GRSP) accumulation in the Hailuogou Glacier Chronosequence, located on the eastern Tibetan Plateau. We wanted to reveal the effects of nutrient limitation on soil microbes and the relative contributions of edaphic and biotic factors. The results showed that with an increasing soil age, there was a steady increase in the microbial biomass and a shift from a bacterial to fungal dominated pattern. Soil enzyme stoichiometry and analyses on threshold elemental ratios revealed that microbial activities are limited by carbon and nitrogen during the early successional stage (3–52 years), while phosphorus was the main limiting factor during later stages (80–120 years). Moreover, the redundancy analysis and structural equation modeling suggested that during early stages edaphic factors had a greater impact on microbial processes, while the vegetation factors were most influential during the last two stages. Overall, these results highlighted the importance of integrating knowledge of the microbial community structure, soil enzyme activities and GRSP to gain a holistic view of soil-plant-microbe interactions during ecosystem successions.

Foundations and Frontiers of Ecosystem Science: Legacy of a Classic Paper (Odum 1969)

Ecosystem ecology, like all scientific disciplines, is often propelled forward by “classic” papers that identify key concepts within the field and define the core questions for generations of scientists. Here, we examine the legacy and sustained impact of a paper long considered a classic in ecology, E.P. (Gene) Odum’s 1969 “The strategy of ecosystem development.” Odum’s paper presented testable predictions about species diversity, energy flow, and biogeochemical dynamics during ecosystem succession and provided guiding principles for environmental conservation and management. Odum’s 24 predictions on “ecosystem development” were a key component of this paper’s legacy: The framework was referenced in 62.0% and tested in 28.7% of 1598 citing papers we examined. Although we found that support for Odum’s framework grew over time, support for any particular prediction was inconsistent, highlighting the unresolved nature of some of the framework’s principles. Odum’s conceptual framework for ecosystem studies—as well as his forward-thinking attempts to connect ecosystem ecology with humans and society—continues to be pertinent to current and future research frontiers. Simplicity of the framework was its strength, and major limitation, painting ecosystem functioning in broad strokes, with no acknowledgement about interactions among the predictions. Newer generations have their work cut out for them by bridging evolutionary biology and ecosystem science or metabolic theory and ecological stoichiometry. Similarly, newer generations are using Odum’s multidisciplinary approach to address the most pressing global change issues and designing solutions that make the Earth life sustaining system compatible with growing human demands.

Understory Community Assembly Following Wildfire in Boreal Forests: Shift From Stochasticity to Competitive Exclusion and Environmental Filtering.

Understory vegetation accounts for the majority of plant species diversity and serves as a driver of overstory succession and nutrient cycling in boreal forest ecosystems. However, investigations of the underlying assembly processes of understory vegetation associated with stand development following a wildfire disturbance are rare, particularly in Eurasian boreal forests. In this study, we measured the phylogenetic and functional diversity and trait dispersions of understory communities and tested how these patterns changed with stand age in the Great Xing'an Mountains of Northeastern China. Contrary to our expectation, we found that understory functional traits were phylogenetically convergent. We found that random patterns of phylogenetic, functional, and trait dispersions were dominant for most of our surveyed plots, indicating that stochastic processes may play a crucial role in the determination of understory community assembly. Yet, there was an evidence that understory community assembly was also determined by competitive exclusion and environmental filtering to a certain degree, which was demonstrated by the observed clustered phylogenetic and functional patterns in some plots. Our results showed that phylogenetic diversity significantly decreased, while functional diversity increased with stand age. The observed shift trends in phylogenetic and functional patterns between random to clustering along with stand age, which suggested that understory community assembly shifted from stochasticity to competitive exclusion and environmental filtering. Our study presented a difference to community assembly and species coexistence theories insisted solely on deterministic processes. These findings indicated that Eurasian boreal understory communities may be primarily regulated by stochastic processes, providing complementary evidence that stochastic processes are crucial in the determination of community assembly both in tropical and boreal forests.

Site conditions and vegetation determine phosphorus and sulfur speciation in soils of Antarctica

Phosphorus (P) and sulfur (S) are essential elements for life, and peculiarities of Antarctic soils regarding their S and P status likely affect terrestrial and aquatic ecosystems in Antarctica. Current climate warming is accompanied by deglaciation, increased availability of water, and vegetation establishment in many regions of Antarctica. The effect of these changes on soil P and S availability, ecosystem succession, mineral weathering, and important processes of soil formation and geochemistry (e.g. organic carbon sequestration, formation of secondary minerals) are largely unknown. Detailed knowledge on different P and S pools in soils of Antarctica is required for sound predictions of climate warming effects on important (bio)geochemical processes. We quantified the P and S concentration and speciation for various Antarctic soils using synchrotron-based X-ray absorption near edge structure (XANES) spectroscopy and related the soil P and S status to important soil and site properties. The soils, which have mostly remained at an initial stage of pedogenesis, differed considerably with respect to their P and S status. The P stock of most soils was dominated by Ca-bound (apatite) P (60–70% of total P). Some soils showed a marked accumulation of either Al-bound P (up to 60% of total P), Fe-bound P (up to 57%), Na- and K-bound P (up to 37%), or organic P (up to 54%). The S speciation also differed considerably among soils. Similar to other terrestrial environments, we observed a transformation of lithogenic apatite P and sulfide S into Al- and Fe-bound phosphate and sulfate as well as organic S and P. The transformation proceeded much more slowly than in soils with temperate humid climate, reflecting the cold and arid climate as well as the absence of vascular plants. The different P and S status of the soils could be related to the following site factors: (i) Parent material – soils formed from basalt had larger contents of total P as well as Al- and Fe-bound P compared to soils formed from mixture of basalt and sandstone. (ii) Sea spray influence – An upland soil affected by eolian deposition of sea spray showed topsoil enrichment of alkali-bound P, Ca-bound P, and CaSO4. (iii) Inundation by seawater – Soils inundated by seawater had higher total P and S concentrations and higher concentrations of inorganic sulfide than upland soils. (iv) Soil moisture – Soils with increased soil moisture or wet conditions showed increased concentrations of P bound to pedogenic Al and Fe minerals and smaller contributions of Ca-bound (apatite) P to total P than soils under permanently arid conditions. (v) Colonization by mosses – Moss establishment resulted in topsoil P depletion and transformation of apatite P into Al- and Fe-bound P, but also in topsoil S accumulation and conversion of sulfide S into organic S forms. According to our study, the ongoing climate warming in Antarctica at many places will likely change soil P and S speciation as well as P and S availability to terrestrial and aquatic ecosystems, thus altering key biogeochemical processes like mineral weathering, secondary mineral formation, and soil C sequestration.

Biogeomorphic feedbacks and the ecosystem engineering of recently deglaciated terrain

Matthews’ 1992 geoecological model of vegetation succession within glacial forefields describes how following deglaciation the landscape evolves over time as the result of both biotic and abiotic factors, with the importance of each depending on the level of environmental stress within the system. We focus in this paper on how new understandings of abiotic factors and the potential for biogeomorphic feedbacks between abiotic and biotic factors makes further development of this model important. Disturbance and water dynamics are two abiotic factors that have been shown to create stress gradients that can drive early ecosystem succession. The subsequent establishment of microbial communities and vegetation can then result in biogeomorphic feedbacks via ecosystem engineering that influence the role of disturbance and water dynamics within the system. Microbes can act as ecosystem engineers by supplying nutrients (via remineralization of organic matter and nitrogen fixation), enhancing soil development, either decreasing (encouraging weathering) or increasing (binding sediment grains) geomorphic stability, and helping retain soil moisture. Vegetation can act as an ecosystem engineer by fixing nitrogen, enhancing soil development, modifying microbial community structure, creating seed banks, and increasing geomorphic stability. The feedbacks between vegetation and water dynamics in glacial forefields are still poorly studied. We propose a synthesized model of ecosystem succession within glacial forefields that combines Matthews’ initial geoecological model and Corenblit's model to illustrate how gradients in environmental stress combined with successional time drive the balance between abiotic and biotic factors and ultimately determine the successional stage and potential for biogeomorphic feedbacks.

Changes in spider diversity and community structure along abandonment and vegetation succession in rice paddy ecosystems

Field abandonment is a new threat to the biodiversity of agricultural land, but its impacts on arthropod communities remain unclear. We investigated how field abandonment influences spider abundance and diversity in rice paddy ecosystems. We collected spiders in paddy fields and six types of abandoned fields with different combinations of vegetation successional stage (early, middle, or late) and soil water content (wet or dry) in Ibaraki Prefecture, Japan. The abundance and species richness of cursorial spiders were higher in the abandoned fields than in the paddy fields, but there was no difference in the case of orb-weavers. Total spider abundance decreased with increasing successional stage, but the responses differed between orb-weavers and cursorial spiders: the abundance of orb-weavers decreased in the middle stage, whereas that of cursorial spiders decreased in the late stage. Soil water content affected only the abundance of orb-weavers: abundance was higher on wet soil than on dry soil. Species richness was not affected by either vegetation succession or soil water content. On the other hand, an individual-based species-accumulation curve showed that rarefied species richness tended to be greater in abandoned fields at the late stage. Ordination analysis showed that species composition clearly differed among paddy and abandoned fields at different successional stages. Our findings suggest that spider abundance and diversity are higher in abandoned fields than in cultivated fields, and that species composition varies depending on field abandonment and succession. Therefore, maintaining cultivated fields and abandoned fields at different successional stages can maintain a high diversity of spiders across rice paddy ecosystems.

An effectual leadership perspective for developing rural entrepreneurial ecosystems

This study articulates the importance of an entrepreneurial method approach to leadership, relevant contextual issues, and policy implications for developing entrepreneurial ecosystems in a rural context. The entrepreneurial method is proposed as the foundations of a new leadership style to facilitate the creation and success of rural entrepreneurial ecosystems. The contextual issues that make rural entrepreneurial ecosystems unique include the critical need for entrepreneurial leadership in their creation and development; the role of entrepreneurial social infrastructure in enabling and supporting development; the need to leverage networks and virtual platforms to access markets, knowledge, and funding; the scarcity of and need to develop enterprising individuals; the role of institutions and supportive governance; and the importance of natural capital.

Permafrost landslides promote soil CO2 emission and hinder C accumulation

Landslides are common in high-latitude forest ecosystems that have developed on permafrost. The most vulnerable areas in the permafrost territories of Siberia occur on the south-facing slopes of northern rivers, where they are observed on about 20% of the total area of river slopes. Landslide disturbances will likely increase with climate change especially due to increasing summer–autumn precipitation. These processes are the most destructive natural disturbance agent and lead to the complete removal of pre-slide forest ecosystems (vegetation cover and soil). To evaluate postsliding ecosystem succession, we undertook integrated ecological research at landslides of different age classes along the Nizhnyaya Tunguska River and the Kochechum River (Tura, Krasnoyarsk region, Russia). Just after the event (at the one-year-old site), we registered a drop in soil respiration, a threefold lower microbial respiration rate, and a fourfold smaller mineral soil carbon and nitrogen stock at bare soil (melkozem) plots at the middle location of the site as compared with the non-affected control site. The recovery of disturbed areas began with the re-establishment of plant cover and the following accumulation of an organic soil layer. During the 35-year succession (L1972), the accumulated layer (O-layer) at the oldest site contained similar C- and N stocks to those found at the control sites. However, the mineral soil C- and N stocks and the microbial biomass – even of the oldest landslide area – did not reach the value of these parameters in control plots. Later, the soil respiration level and the eco-physiological status of soil microbiota also recovered due to these changes. This study demonstrates that the recovery after landslides in permafrost forests takes several decades. In addition, the degradation of permafrost due to landslides clearly hinders the accumulation of soil organic matter in the mineral soil.

Rapid microevolution during recent range expansion to harsh environments

BackgroundAdaptive evolution is one of the crucial mechanisms for organisms to survive and thrive in new environments. Recent studies suggest that adaptive evolution could rapidly occur in species to respond to novel environments or environmental challenges during range expansion. However, for environmental adaptation, many studies successfully detected phenotypic features associated with local environments, but did not provide ample genetic evidence on microevolutionary dynamics. It is therefore crucial to thoroughly investigate the genetic basis of rapid microevolution in response to environmental changes, in particular on what genes and associated variation are responsible for environmental challenges. Here, we genotyped genome-wide gene-associated microsatellites to detect genetic signatures of rapid microevolution of a marine tunicate invader, Ciona robusta, during recent range expansion to the harsh environment in the Red Sea.ResultsThe Red Sea population was significantly differentiated from the other global populations. The genome-wide scan, as well as multiple analytical methods, successfully identified a set of adaptive genes. Interestingly, the allele frequency largely varied at several adaptive loci in the Red Sea population, and we found significant correlations between allele frequency and local environmental factors at these adaptive loci. Furthermore, a set of genes were annotated to get involved in local temperature and salinity adaptation, and the identified adaptive genes may largely contribute to the invasion success to harsh environments.ConclusionsAll the evidence obtained in this study clearly showed that environment-driven selection had left detectable signatures in the genome of Ciona robusta within a few generations. Such a rapid microevolutionary process is largely responsible for the harsh environmental adaptation and therefore contributes to invasion success in different aquatic ecosystems with largely varied environmental factors.

Element Composition of Mushrooms in Contrasting Anthropogenic Loading

Environmental macro- and microelements in both unpolluted and polluted areas are cycled by the active participation of higher fungi. ICP-MS and fluorimetric Se analysis were used to determine, under conditions of contrasting anthropogenic loading (in the vicinity of a mineral fertilizer plant), the contents of 21 macro- and microelements in 7 species of mycorrhizal mushrooms: Russula vesca, Lactaiuspubescens, Leccinum scrabum, Leccinum aurantiacum, Helvella crispa, Suillus luteus andSuillus granulates; and in two species of saprophytes: Pubescens involutus and Morchella esculenta. Among the studied ecosystems, the new successional ecosystem of an abundant phosphogypsum storage site was characterized by the highest levels of Sr accumulation by mushrooms, whereas the artificial ecosystem of the plant’s territory was responsible for mushrooms accumulating high amounts of Al, Fe, Pb, V and Сd. The cumulative ecosystem area near the abundant phosphogypsum storage site demonstrated higher levels of Pb and lower levels of Al, Cr, Ni, V and Co in mushrooms than in the copse at the base of the functioning phosphogypsum storage sites. In conditions of contrasting anthropogenic loading, mycorrhizal fungi of the family Russulacea and saprophytes (P. involutus) demonstrated strong correlations between Al, V and Li; V and Sr; Se and Р; and Li and Fе. In these conditions saprophytes (P. involutus) were characterized by significantly higher accumulations of practically all the studied elements (especially heavy metals) and lower Se concentrations. In conditions of powerful anthropogenic loading, interspecies differences in the element compositions of mycorrhizal mushrooms showed the preferential accumulation of V, Pb, Zn, Fe, Li, and Mn by Helvella crispa; As and Si, by Leccinum scrabum; Cd, Se, and Mn, by Leccinum aurantiacum; Sr, Cr, and B, by R. vesca; Al, Co, and Ni, by L. pubescens; Si and B, by Suillus granulates. The ecological risks of consuming mushrooms collected in the vicinity of the mineral fertilizer plant differed by more than 100 times depending on mushroom species (the most significant were recorded for P. involutus) and place of growth; they decreased from the artificial (territory of the fertilizer plant) to cumulative (vicinity of phosphogypsum storage sites) and succession (territory of the abundant phosphogypsum storage site) ecosystems. Zn had the highest phosphogypsum/mushroom transfer coefficient; Sr, the lowest.

Promoting the creation of Innovation Ecosystems: the case of the University of Porto

Universities are increasingly acting as promoters of innovation, economic growth and regional development, a trend that has attracted the attention of both policy makers and researchers. The objective of this paper is to contribute to a deeper understanding of the role of higher education institutions as dynamic promoters of growth and development. The University of Porto is used as a case study to explore how universities can act as innovation ecosystems leaders and integrators. The main contributions of the paper are threefold. First, the case puts in evidence a key success factor: the talent to transform the knowledge produced by universities into valuable solutions for companies and other organisations. Second, links between universities and industry must assume a long-term and relational nature rather than an intermittent and transactional character. Finally, the success of university-based ecosystems depends on the integration of a diversity of actors, resources and competences. This means that a sustainable strategy of innovation and knowledge valorisation requires an approach that fosters both internal and external networking.

Promoting the creation of Innovation Ecosystems: the case of the University of Porto

Universities are increasingly acting as promoters of innovation, economic growth and regional development, a trend that has attracted the attention of both policy makers and researchers. The objective of this paper is to contribute to a deeper understanding of the role of higher education institutions as dynamic promoters of growth and development. The University of Porto is used as a case study to explore how universities can act as innovation ecosystems leaders and integrators. The main contributions of the paper are threefold. First, the case puts in evidence a key success factor: the talent to transform the knowledge produced by universities into valuable solutions for companies and other organisations. Second, links between universities and industry must assume a long-term and relational nature rather than an intermittent and transactional character. Finally, the success of university-based ecosystems depends on the integration of a diversity of actors, resources and competences. This means that a sustainable strategy of innovation and knowledge valorisation requires an approach that fosters both internal and external networking.

Quantifying Changes on Forest Succession in a Dry Tropical Forest Using Angular-Hyperspectral Remote Sensing

The tropical dry forest (TDF) is one the most threatened ecosystems in South America, existing on a landscape with different levels of ecological succession. Among satellites dedicated to Earth observation and monitoring ecosystem succession, CHRIS/PROBA is the only satellite that presents quasi-simultaneous multi-angular pointing and hyperspectral imaging. These two characteristics permit the study of structural and compositional differences of TDFs with different levels of succession. In this paper, we use 2008 and 2014 CHRIS/PROBA images from a TDF in Minas Gerais, Brazil to study ecosystem succession after abandonment. Using a −55° angle of observation; several classifiers including spectral angle mapper (SAM), support vector machine (SVM), and decision trees (DT) were used to test how well they discriminate between different successional stages. Our findings suggest that the SAM is the most appropriate method to classify TDFs as a function of succession (accuracies ~80 for % for late stage, ~85% for the intermediate stage, ~70% for early stage, and ~50% for other classes). Although CHRIS/PROBA cannot be used for large-scale/long-term monitoring of tropical forests because of its experimental nature; our results support the potential of using multi-angle hyperspectral data to characterize the structure and composition of TDFs in the near future.

Design Rules, Volume 2: How Technology Shapes Organizations: Chapter 14 Introducing Open Platforms and Business Ecosystems.

The purpose of this chapter is to lay the groundwork for a comprehensive theoretical investigation of open digital platform systems. To do this, we must first recognize that, although there is a strong family resemblance among all platform systems, there are different types of platforms, each with its own set of technological requirements and challenges. I first develop a taxonomy of open digital platforms. I go on to argue that the success of open platforms and ecosystems in competition with vertically integrated firms gave rise to the “vertical-to-horizontal” transition of the computer industry described by Andy Grove in 1996. In effect, the technology of open platforms not only shaped individual organizations but changed the structure of the entire computer industry.

3D hydrodynamic investigation of thermal regime in a large river-lake-floodplain system (Poyang Lake, China)

Thermal regime and its response to meteorological and hydrological forcings play an important role in controlling water quality and ecosystem of lakes. Many large floodplain lakes are subjected to significant river-lake interactions and could benefit greatly from hydrodynamic modeling. The current work presents a first attempt to use a 3D hydrodynamic model and statistical methods to explore spatiotemporal variations and primary causal factors of thermal stability within a large river-lake-floodplain system (Poyang Lake, China). The hydrodynamic model successfully reproduced the lake hydrodynamics and thermal dynamics through a comparative analysis of field measurements. Simulation results revealed that the thermal stability of Poyang Lake exhibits similar spatial patterns between seasons; however, the lake is generally stratified during summer and early autumn. It is classified as partial mixed and full mixed during winter and spring. The thermal stratification may develop in the center area and eastern bay area of the lake, while the full mixing is likely to occur in the floodplains and the main flow channels. Statistics and simulations indicate that the air temperature, solar radiation and evaporation trigger a positive effect on the thermal stability of Poyang Lake, whereas a negative relationship is recognized due to the catchment river temperature. The responses of thermal stability to the meteorological and hydrological changes are much stronger in summer than other seasons, producing a significant seasonal thermal regime in the floodplain lake. Additionally, the dynamics in the lake water depth and associated hydrological regime are a major factor in maintaining the seasonal thermal stability of Poyang Lake. The findings of this study can support management of Poyang Lake as well as other similar floodplain lakes, by providing information on both water quality and ecosystem succession.

A 110-year pollen record of land use and land cover changes in an anthropogenic watershed landscape, eastern China: Understanding past human-environment interactions

Land use and land cover changes (LUCCs) have largely altered terrestrial ecosystems and landscapes during the Anthropocene. Reconstructing past LUCCs is necessary to better understand terrestrial ecosystem succession and human-environment interactions so that ecosystem services can be used conservatively and developed sustainably. In this paper, we reconstructed the LUCCs over the past century in a typical anthropogenic watershed based on a high-resolution pollen record from Changdang Lake, eastern China. The sediment core was 210Pb dated and constrained cluster analysis identified different periods of LUCCs associated with the 110-year pollen record. Multi-sedimentary proxies, historical records, and remote sensing LUCC maps were analyzed to complement the palynological results. Our results demonstrate that pollen records can accurately capture LUCCs during different historical periods. Extra-regional arboreal pollen, fern spores, and pollen concentration can record the hydrological variations of waterbodies under both climatic and anthropogenic impacts. Multiple agriculture-related pollen indicators, such as cereal, Cruciferae, and wetland taxa are significantly related to the corresponding vegetation cover and landscape variations. Specifically, the anthropochore taxa to wetland taxa ratio is a good indicator of agricultural intensity. Dominant arboreal pollen (Pinus and Quercus) and the arboreal taxa to non-arboreal taxa ratio reflects the forestry landscape changes. Urban greening arboreal pollen (including Platanus, Salix, and Ulmus) is found to be an indirect indicator of urbanization. In addition, agriculture and urbanization in the region are causing the pollen diversity to increase in lake sediments. This study from a shallow lake in eastern China contributes to our understanding of pollen-based LUCC studies in similar climatic and anthropogenic regions around the world.

Ecological processes determining the distribution dynamics of vole populations during forest succession.

The size and distribution of animal populations may vary drastically over time following a disturbance event. While both competition and predation can control the size of animal populations, changes in the relative importance of these two density-dependent processes remain poorly documented during ecological succession. Here, we combined habitat selection and optimal foraging theory to identify the processes that can explain the increase in red-backed voles (Myodes gapperi) during post-logging forest succession in boreal ecosystems. Specifically, we assessed the extent to which changes in intra- and interspecific competition and in predation risk can explain variation in abundance and distribution of voles during post-harvest forest succession. We estimated the abundances of the red-backed vole and of its main competitor, the deer mouse (Peromyscus maniculatus), in adjacent pairs of logged (5-66years old) forest stands and uncut stands (> 120years old). We found that voles increased their preference for uncut stands with increasing conspecific density. Foraging experiments revealed that in early-seral forest stands, voles increased their feeding effort in the presence of deer mice, particularly in safer food patches. This behaviour is expected from foraging theory when interspecific competitors increase predation risk. Apparent competition would thus limit the density of red-backed voles, and changes in the relative strength of this process during forest succession would control patterns of distribution and abundance of the species.