External Environmental Drivers Research Articles

Exploring the External Environmental Drivers of Honey Bee Colony Development

Honey bees play an important role in agricultural landscapes by providing pollination services. Throughout the season, colonies increase their population and collect resources from the available flowering plants. Besides internal mechanisms, such as the amount of brood or the availability of bees to perform foraging flights, colonies are also influenced by the climate and the surrounding landscape. Therefore, exposure to different environmental contexts leads to distinct development rates. In this study, we show how colonies develop under three different landscape contexts and explore which external variables (mostly climate and resources availability) influence the colonies’ development. We installed three apiaries in three different landscapes in the Iberian Peninsula, with temporal and spatial variation in climatic conditions and resource availability. The availability of resources and their use, as well as the development of colonies throughout the season, were thoroughly investigated. These data were used to take the first step into creating an ecologically relevant landscape by calculating the number of available resources in the landscape at different points in time, based on plants’ beekeeping interest as well as nectar and production. Furthermore, climatic variables were transformed into the amount of available foraging minutes that bees had to collect resources, and a theoretical threshold of optimal vs. sub-optimal conditions was also explored. Interestingly, the main drivers of colony development (measured by daily weight increase) were not the same in the tested apiaries, evidencing how colonies are indeed intrinsically connected with the surrounding environmental scenario. Therefore, results from field testing are extremely context-dependent and should be interpreted with caution when being extrapolated to other environmental scenarios.

The patterns and driving forces of dengue invasions in China

BackgroundGlobal connectivity and environmental change pose continuous threats to dengue invasions from worldwide to China. However, the intrinsic relationship on introduction and outbreak risks of dengue driven by the landscape features are still unknown. This study aimed to map the patterns on source-sink relation of dengue cases and assess the driving forces for dengue invasions in China.MethodsWe identified the local and imported cases (2006–2020) and assembled the datasets on environmental conditions. The vector auto-regression model was applied to detect the cross-relations of source-sink patterns. We selected the major environmental drivers via the Boruta algorithm to assess the driving forces in dengue outbreak dynamics by applying generalized additive models. We reconstructed the internal connections among imported cases, local cases, and external environmental drivers using the structural equation modeling.ResultsFrom 2006 to 2020, 81,652 local dengue cases and 12,701 imported dengue cases in China were reported. The hotspots of dengue introductions and outbreaks were in southeast and southwest China, originating from South and Southeast Asia. Oversea-imported dengue cases, as the Granger-cause, were the initial driver of the dengue dynamic; the suitable local bio-socioecological environment is the fundamental factor for dengue epidemics. The Bio8 [odds ratio (OR) = 2.11, 95% confidence interval (CI): 1.67–2.68], Bio9 (OR = 291.62, 95% CI: 125.63–676.89), Bio15 (OR = 4.15, 95% CI: 3.30–5.24), normalized difference vegetation index in March (OR = 1.27, 95% CI: 1.06–1.51) and July (OR = 1.04, 95% CI: 1.00–1.07), and the imported cases are the major drivers of dengue local transmissions (OR = 4.79, 95% CI: 4.34–5.28). The intermediary effect of an index on population and economic development to local cases via the path of imported cases was detected in the dengue dynamic system.ConclusionsDengue outbreaks in China are triggered by introductions of imported cases and boosted by landscape features and connectivity. Our research will contribute to developing nature-based solutions for dengue surveillance, mitigation, and control from a socio-ecological perspective based on invasion ecology theories to control and prevent future dengue invasion and localization.Graphical

Stochastic Modelling to Assess External Environmental Drivers of Atlantic Chub Mackerel Population Dynamics

The population dynamics of small and middle-sized pelagic fish are subject to considerable interannual and interdecadal fluctuations in response to fishing pressure and natural factors. However, the impact of environmental forcing on these stocks is not well documented. The Moroccan Atlantic coast is characterized by high environmental variability due to the upwelling phenomenon, resulting in a significant abundance and variation in the catches of small and middle-sized pelagic species. Therefore, understanding the evolution of stock abundance and its relationship with different oceanographic conditions is a key issue for fisheries management. However, because of the limited availability of independent-fishery data along the Moroccan Atlantic coast, there is a lack of knowledge about the population dynamics. The main objective of this study is to test the correlation between the environment conditions and the stock fluctuations trends estimated by a stock assessment model that does not need biological information on growth, reproduction, and length or age structure as input. To achieve this objective, the fishery dynamics are analyzed with a stochastic surplus production model able to assimilate data from surveys and landings for a biomass trend estimation. Then, in a second step, the model outputs are correlated with different environmental (physical and biogeochemical) variables in order to assess the influence of different environmental drivers on population dynamics. This two-step procedure is applied for chub mackerel along the Moroccan coast, where all these available datasets have not been used together before. The analysis performed showed that larger biomass estimates are linked with periods of lower salinity, higher chlorophyll, higher net primary production, higher nutrients, and lower subsurface oxygen, i.e., with an enhanced strength of the upwelling. In particular, acute anomalies of these environmental variables are observed in the southern part presumably corresponding to the wintering area of the species in the region. The results indicate that this is a powerful procedure, although with important limitations, to deepen our understanding of the spatiotemporal relationships between the population and the environment in this area. Moreover, once these relationships have been identified, they could be used to generate a mathematical relationship to simulate future population trends in diverse environmental scenarios.

Lake ecosystem regime shifts induced by agricultural intensification: A century scale paleolimnological investigation from the Huai River Basin (China)

Regime shifts of freshwater ecosystems driven by fast-changing multiple stressors are increasingly occurring. However, lake regime shifts across intensive agricultural landscapes are less explored, especially how different aquatic communities respond to multiple environmental forcings through time is poorly understood. Using a century scale paleolimnological record from Gaoyou Lake in the Huai River Basin, one of the most intensively cultivated areas in China, we analyzed high-resolution sedimentary subfossil pigments and cladoceran assemblages to investigate the dynamic trajectories of plankton communities and detect the potential occurrence of ecological shifts across different aquatic trophic levels. Furthermore, we explored how these shifts were driven by anthropogenic and climatic stressors, and examined the rates of ecological change through time. Our results revealed a significant ecological shift in the cladoceran community around the 1970s associated with the hydrological regulation through damming within the basin. Subsequently, a regime shift for the whole-lake ecosystem occurred in the 1990s, which was characterized by the onset of eutrophication with elevated primary production and decreased water clarity. Redundancy and variance partitioning analyses identified agricultural intensification with substantial anthropogenic nutrient loading as the main driver of lake ecological dynamics. Rising temperature played an additional role. Moreover, we detected two significant acceleration phases of lake primary productivity (in the 1990s and after the 2000s), which were asynchronous with the variability of external environmental drivers. This finding probably indicated Gaoyou Lake has switched from a slow-to a fast-response system with decreasing ecological stability. Our study offers new challenges and insights for incorporating rate-focused management strategies to minimize the risk of catastrophic ecological shifts in aquatic ecosystems.

Seasonality of Recharge Drives Spatial and Temporal Nitrate Removal in a Karst Conduit as Evidenced by Nitrogen Isotope Modeling

AbstractNitrogen removal rates can vary with time, space, and external environmental drivers, but are underreported for karst environments. We carried out a multi‐year study of a karst conduit where we: (a) measured inputs and outputs of sediment nitrogen (SN and δ15NSed) and nitrate (NO3− and δ15NNO3); (b) developed, calibrated, and applied a numerical model of nitrogen physics and biogeochemistry; and (c) forecasted the impacts of climate and land use changes on nitrate removal and export. Data results from conduit inputs (SN = 0.43% ± 0.07%, δ15NSed = 5.07‰ ± 1.01‰) and outputs (SN = 0.36% ± 0.09%, δ15NSed = 6.45‰ ± 0.71‰) indicate net‐mineralization of SN and increase of δ15NSed (p < 10−2). However, δ15NSed increase cannot be explained by SN mineralization alone and is instead accompanied by immobilization of isotopically heavier mineral nitrogen (δ15NNO3 = 11.25‰ ± 6.96‰). Modeled SN and δ15NSed sub‐routines provided a boundary condition for DIN simulation and improved NO3− model performance (from NSE = 0.06 to NSE = 0.68). Modeled spatial zones of removal occur in close proximity to conduit entrances, where deposition of labile organic matter promotes a three‐fold increase in denitrification (∼60 mg N m−2 d−1). Modeled temporal periods of removal occur during the dry‐season where longer residence times cause up to 90% removal of NO3− inputs. Projected effects of environmental drivers suggest an increase in denitrification (+14.1%); however, this removal is largely offset by greater nitrate soil leaching (+28.1%) from wetter regional climate. Results suggest that conduits underlying mature karst terrain experience spatiotemporal removal gradients, which are modulated by solute and sediment delivery.

The Role of Thermal Denudation in Erosion of Ice-Rich Permafrost Coasts in an Enclosed Bay (Gulf of Kruzenstern, Western Yamal, Russia)

Coastal erosion in the Arctic has numerous internal and external environmental drivers. Internal drivers include sediment composition, permafrost properties and exposure which contribute to its spatial variability, while changing hydrometeorological conditions act as external drivers and determine the temporal evolution of shoreline retreat. To reveal the relative role of these factors, we investigated patterns of coastal dynamics in an enclosed bay in the southwestern Kara Sea, Russia, namely the Gulf of Kruzenstern, which is protected from open-sea waves by the Sharapovy Koshki Islands. Using multitemporal satellite imagery, we calculated decadal-scale retreat rates for erosional segments of the coastal plain from 1964 to 2019. In the field, we studied and described Quaternary sediments and massive ground-ice beds outcropping in the coastal bluffs. Using data from regional hydrometeorological stations and climate reanalysis (ERA), we estimated changes in the air thawing index, sea ice-free period duration, wind-wave energy and total hydrometeorological stress for the Gulf of Kruzenstern, and compared it to Kharasavey and Marre-Sale open-sea segments north and south of the gulf to understand how the hydrometeorological forcing changes in an enclosed bay. The calculated average shoreline retreat rates along the Gulf in 1964–2010 were 0.5 ± 0.2 m yr−1; the highest erosion of up to 1.7 ± 0.2 m yr−1 was typical for segments containing outcrops of massive ground-ice beds and facing to the northwest. These retreat rates, driven by intensive thermal denudation, are comparable to long-term rates measured along open-sea sites known from literature. As a result of recent air temperature and sea ice-free period increases, average erosion rates rose to 0.9 ± 0.7 m yr−1 in 2010–2019, with extremes of up to 2.4 ± 0.7 m yr−1. The increased mean decadal-scale erosion rates were also associated with higher spatial variability in erosion patterns. Analysis of the air thawing index, wave energy potential and their total effect showed that inside the Gulf of Kruzenstern, 85% of coastal erosion is attributable to thermal denudation associated with the air thawing index, if we suppose that at open-sea locations, the input of wave energy and air thawing index is equal. Our findings highlight the importance of permafrost degradation and thermal denudation on increases in ice-rich permafrost bluff erosion in the Arctic.

Climate change will cause non-analog vegetation states in Africa and commit vegetation to long-term change

Abstract. Vegetation responses to changes in environmental drivers can be subject to temporal lags. This implies that vegetation is committed to future changes once environmental drivers stabilize; e.g., changes in physiological processes, structural changes, and changes in vegetation composition and disturbance regimes may happen with substantial delay after a change in forcing has occurred. Understanding the trajectories of such committed changes is important as they affect future carbon storage, vegetation structure, and community composition and therefore need consideration in conservation management. In this study, we investigate whether transient vegetation states can be represented by a time-shifted trajectory of equilibrium vegetation states or whether they are vegetation states without analog in conceivable equilibrium states. We use a dynamic vegetation model, the aDGVM (adaptive Dynamic Global Vegetation Model), to assess deviations between simulated transient and equilibrium vegetation states in Africa between 1970 and 2099 for the RCP4.5 and 8.5 scenarios using regionally downscaled climatology based on the MPI-ESM output for CMIP5. We determined lag times and dissimilarity between simulated equilibrium and transient vegetation states based on the combined difference of nine selected state variables using Euclidean distance as a measure for that difference. We found that transient vegetation states over time increasingly deviated from equilibrium states in both RCP scenarios but that the deviation was more pronounced in RCP8.5 during the second half of the 21st century. Trajectories of transient vegetation change did not follow a “virtual trajectory” of equilibrium states but represented non-analog composite states resulting from multiple lags with respect to vegetation processes and composition. Lag times between transient and most similar equilibrium vegetation states increased over time and were most pronounced in savanna and woodland areas, where disequilibrium in savanna tree cover frequently acted as the main driver of dissimilarities. Fire additionally enhanced lag times and dissimilarity between transient and equilibrium vegetation states due to its restraining effect on vegetation succession. Long lag times can be indicative of high rates of change in environmental drivers, of meta-stability and non-analog vegetation states, and of augmented risk for future tipping points. For long-term planning, conservation managers should therefore strongly focus on areas where such long lag times and high residual dissimilarity between most similar transient and equilibrium vegetation states have been simulated. Particularly in such areas, conservation efforts need to consider that observed vegetation may continue to change substantially after stabilization of external environmental drivers.

Exploring the retail industry environment using nonlinear analysis

PurposeThe purpose of this paper is to explore the dynamics of the relationships between sales and internal and external environmental drivers in a retail company using a systems perspective in order to support retail management decisions with nonlinear methods.Design/methodology/approachThe research and results are presented in two parts: the collection and explorative analysis of the data; and discussion of the managerial implications following a systems perspective. The exploratory analysis is conducted using a statistical comparison of linear and nonlinear models of sales data from a retail company. The data, which comprise two data sets, come from 45 retail stores located in different regions of the USA.FindingsSpecifically, nonlinear models provided a better explanation of variation in retail activity (R2=46 per cent) than linear models (R2=16 per cent). In such a situation, the nonlinear analysis captures the influence of internal and external environmental drivers on retail sales.Research limitations/implicationsWith a limited variety of external and internal drivers, the exploratory analysis aims to describe a general situation in which retailers are managing activities in complex environments as opposed to reflect on a particular retail chain.Practical implicationsThe systems perspective is used to interpret the managerial implications of the nonlinear analysis fits, particularly in cases where retail decision-makers are adapting, transforming and restructuring sources of competitive advantage in complex environments.Originality/valueThe paper provides an alternative perspective (the systemic one) of how retailers could interpret the relationships between internal and external variables in the dynamic environment of the retail chains with nonlinear models.

Effects of climate change on zooplankton community interactions in an Alaskan lake

BackgroundEcological communities are organized by interactions among the biota, and between the biota and external environmental drivers that affect the dynamics of individual taxa. Climate change may alter communities in unexpected ways when environmental drivers have complex effects on individual species that are then transmitted indirectly to other species via biotic interactions.MethodsWe used a multivariate autoregressive (MAR) modeling framework to assess the strengths of intrinsic interactions and extrinsic (environmental) forcing responsible for changes in the zooplankton community of a sockeye salmon nursery lake in southwestern Alaska from 1963 to 2009. During this time period there has been a strong trend towards earlier spring ice breakup dates and warmer summer water temperatures.ResultsMAR analyses of community time-series showed that water temperature was the dominant driver of change in the zooplankton community; competitive interactions were relatively rare, and only copepods (both cyclopoids and calanoids) were affected by predation (juvenile sockeye salmon). Best-fit community models were used to develop scenarios of zooplankton community composition under several different potential climate conditions and salmon densities and revealed the potential for a shift in the dominant zooplankton taxa in this lake, driven largely by taxon-specific sensitivity to climate and sockeye salmon predation.ConclusionsSimulations suggest that cladocerans will become more prevalent in this community and that calanoid copepods will suffer from ongoing climate warming. These results have important implications for fish in these northern lakes, as they suggest that the production of planktivorous fish should increase with ongoing climate change.

Two-zone model for stream and river ecosystems

A mechanistic two-zone model is developed to represent the food web dynamics of stream and river ecosystems by considering the benthic and nonbenthic (or water-column) zones as two separate, but interacting biotopes. Flow processes, solar radiation, and temperature are the dynamic external environmental drivers. State variables are defined to represent the hierarchical levels of detritus, limiting nutrient, vegetation, and invertebrates. The fish trophic level is included as a constant input parameter. Model parameters, constants, and boundary conditions are defined based on watershed as well as channel hydrology, stream geomorphology, and biological activities. Recent advances in ecological science and engineering are used in representing important biogeochemical processes. In particular, the turbulent diffusion, as well as sloughing or detachment, processes are defined based on these recent advancements. The two-zone model was evaluated for a gravel bed prealpine Swiss stream named River Necker with data for the study period of January 1992 through December 1994. The model was able to capture the general trends and magnitudes of the food web state variables. A comprehensive relative sensitivity analysis with five moment-based measures found that approximately 5% of the model parameters were important in predicting benthic vegetation. Results of sensitivity analysis guided the model calibration. Simulated benthic vegetation with the calibrated model, which was obtained by adjusting only four parameters, corresponded with observed data. Hydrology-dependent sloughing and detachment were dominant in determining the response of benthic vegetation and invertebrates. The proposed two-zone food web model is a potentially useful research tool for stream and river ecosystems.

Success in electronic commerce implementation

PurposeThe purpose of this paper is to develop a model of electronic commerce (EC) implementation success for small to medium‐sized enterprises (SMEs), and to present outcomes of a comparative study between two countries to reflect the differences in the adoption strategies and explore reasons behind such variations.Design/methodology/approachPreliminary studies were conducted in both Australia and Singapore prior to a cross‐country survey, which collected the perceptions of small businesses about their experience with internet‐based EC. Multiple regression analysis was conducted to identify the influencing factors that affect success in the implementation of internet‐based EC.FindingsBy regressing overall satisfaction on the 19 influencing factors of EC success, the paper found that five factors: observability; communication channel; customer pressure; supplier pressure; and perceived governmental support, make significant contribution to the adoption of internet‐based EC in Australia; and only three factors: firm size; perceived readiness; and observability, have significant impact in Singapore.Research limitations/implicationsThe exploratory nature of the research means confirmatory or causally directional hypotheses could be generated in the future. It would also be insightful to conduct longitudinal studies to confirm the direction, to help clarify causality and test for feedback effects of adoption decisions. There was also no attempt made to control for industry type, which could tested more intensively in a chosen industry. Generalisability to other geographical context could be achieved if the research model can be tested over several other countries.Practical implicationsThe study has found that the proposed model can be used in investigating drivers of EC implementation in SMEs, and the empirical data has adequately supported the model. The findings show that the organisational and innovation characteristics are necessary, but to provide a more comprehensive picture in explaining the implementation behaviour of SMEs, one needs to consider other factors and contexts especially when testing the model in different countries. Communication methods employed, government support, external pressure from customers and suppliers have been found to be very important for Australian SMEs in this decision.Originality/valueA major contribution of this study is that it provides an understanding of what the organisational, technological, communication, and external environmental drivers of EC implementation are. The findings of this study could also help companies embarking upon cross border activities by illustrating the differences in EC adoption between the two Asia‐Pacific nations. The study also provides a close examination of the inhibiting and facilitating factors which can affect EC adoption success. By knowing the relative importance of these factors, SMEs may be spared from expending their limited resources and energy on less important factors which have limited contribution to EC implementation success.

Temporal trajectories of phosphorus and pedo-patterns mapped in Water Conservation Area 2, Everglades, Florida, USA

Documenting local change of soil properties over longer periods of time is critical to assess trends along trajectories. We present two types of temporal trajectories that document change in soil phosphorus (P) and pedo-patterns in Water Conservation Area 2, a subtropical wetland in the Everglades, Florida. Our specific objectives were to (i) quantify the spatial distribution of total P (TP) in floc and topsoil at two time periods (1998 and 2003), (ii) create TP change maps using a crisp, geospatial mapping approach, (iii) analyze relationships between floc/soil TP temporal trajectories and vegetation, and (iv) describe change in pedo-patterns using fuzzy sets to account for the uncertainty inherent in crisp soil property mapping. The median TP in floc was 730 mg kg − 1 in 1998 and increased to a median of 751 mg kg − 1 in 2003; whereas the median in soil was 485 mg kg − 1 in 1998 that decreased to 433 mg kg − 1 in 2003. Floc TP change trajectories varied between 0–990 mg kg − 1 (increase) and 0–2900 mg kg − 1 (decrease); and soil TP change trajectories varied between 0–370 mg kg − 1 (increase) and 0–1439 mg kg − 1 (decrease). Phosphorus-enriched sites were associated with nutrient influx via surface waters and showed linkages to expanding Typha domengensis vegetation. The temporal trajectories of pedo-patterns provided pixel-specific signatures of ecosystem processes such as P enrichment, organic matter turnover, hydrologic shifts, and fire in form of fuzzy membership values. The fuzzy set-based temporal trajectory maps provided a holistic approach documenting shifts in this ecosystem due to external environmental drivers and biogeochemical processes within a 5-year period.

Sustainable Supply Network Management

This article presents an overview of current practices in managing sustainability (social, ethical, environmental) issues in supply networks. It is based on an examination of eight economic sectors in Europe and North America, including utilities, transport, information and communication technology (ICT), retail, tourism and leisure, construction, chemicals and the public sector. It was found that for the vast majority of organisations, the incorporation of sustainability issues is a new area of activity and many have yet to begin managing them in their supply networks. Of those that are active, most have so far only focused on environmental issues. This is largely due to the presence of external environmental drivers, such as legislation, market pressure and media attention, and a lack of external pressures for social and ethical issues in most sectors. So far, tools and strategies have predominantly focused on the procurement process and the management of corporate risk. However, cutting edge organisations are exploring partnership approaches for sharing knowledge, solving shared problems and harnessing opportunities for competitive advantage.