Biophysical Gradients Research Articles

Factors affecting recruitment, growth and survival of the eastern oyster Crassostrea virginica across an intertidal elevation gradient in southern New England

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 609:119-132 (2019) - DOI: https://doi.org/10.3354/meps12830 Factors affecting recruitment, growth and survival of the eastern oyster Crassostrea virginica across an intertidal elevation gradient in southern New England Christopher J. Baillie1,*, Jonathan H. Grabowski2 1Institute of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell Street, Morehead City, North Carolina 28557, USA 2Marine Science Center, Northeastern University, 430 Nahant Road, Nahant, Massachusetts 01908, USA *Corresponding author: baillie@email.unc.edu ABSTRACT: Reef-building oysters are important coastal foundation species that provide ecosystem services. Overharvesting, destructive fishing practices, and environmental degradation have caused significant declines in global oyster populations, necessitating restoration efforts in many regions to rebuild oyster habitat and recover lost services. Understanding how biological and physical gradients regulate oyster recruitment, survivorship and growth will help guide future efforts to successfully restore oyster populations. We conducted a field experiment in Ipswich, Massachusetts, to quantify the effects of tidal elevation, predator exclusion, and reef vertical relief on oyster settlement, recruitment and survivorship. Oyster settlement was 3 times greater at the deepest intertidal elevation compared to the 2 shallower intertidal elevations. Reef vertical relief and predator exclusion did not affect oyster settlement or survivorship. Despite increased sedimentation and algal fouling with increasing depth, living oyster densities remained significantly elevated at the deepest intertidal elevation 8 mo after the experimental reefs were constructed. Oyster mortality during this period was highest (>70%) at our shallowest elevation treatment, likely the result of desiccation and food limitation. Meanwhile, mortality during the first winter post-recruitment was high across all elevations (all >64%), with our deepest elevation treatment experiencing the highest mortality rate (90%). Our results suggest that there is a gradient in oyster settlement rates, which increase at lower elevation, and that the dominant drivers of mortality also likely vary with elevation. Our findings highlight the need for region-specific studies to quantify biological and physical gradients prior to large-scale restoration efforts. KEY WORDS: Crassostrea virginica · Oyster · Restoration · Biophysical gradients Full text in pdf format PreviousNextCite this article as: Baillie CJ, Grabowski JH (2019) Factors affecting recruitment, growth and survival of the eastern oyster Crassostrea virginica across an intertidal elevation gradient in southern New England. Mar Ecol Prog Ser 609:119-132. https://doi.org/10.3354/meps12830 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 609. Online publication date: January 17, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Drivers of basal area variation across primary late-successional Picea abies forests of the Carpathian Mountains

Disentangling the importance of developmental vs. environmental drivers of variation in forest biomass is key to predicting the future of forest carbon sequestration. At coarse scales, forest biomass is likely to vary along major climatic and physiographic gradients. Natural disturbance occurs along these broad biophysical gradients, and depending on their extent, severity and frequency, could either amplify or dampen spatial heterogeneity in forest biomass. Here we evaluate spatial variation in the basal area of late-successional Picea abies (L./Karst.) forests across the Carpathian Mountain Range of central Europe and compare the roles of coarse-scale biophysical gradients and natural disturbances in driving that variation across a hierarchy of scales (landscapes, stands, and plots). We inventoried forest composition and structure, and reconstructed disturbance histories using tree cores collected from 472 plots nested within 30 late-successional stands, spanning the Carpathian Mountains (approximately 4.5 degrees of latitude). We used linear mixed-effects models to compare the effect of disturbance regimes and site conditions on stand basal area at three hierarchical scales. We found that the basal area of late-successional Picea abies forests varied across a range of spatial scales, with climatic drivers being most important at coarse scales and natural disturbances acting as the primary driver of forest heterogeneity at fine scales. For instance, the stand-level basal area varied among landscapes, with the highest values (48–68 m2 ha−1) in the warmer southern Carpathian Mountains, and lower values (37–52 m2 ha−1 on average) in cooler areas of the eastern and western Carpathians. Finer-scale variation was driven by local disturbances (mainly bark beetle and windstorms) and the legacies of disturbances that occurred more than a century ago. Our findings suggest that warming could increase the basal area of northern sites, but potential increasing disturbances could disrupt these environmental responses.

Gardener Well-Being along Social and Biophysical Landscape Gradients

Increasing human populations are challenging cities to grow sustainably while maintaining green spaces that deliver ecosystem services and well-being benefits. Community gardens are green spaces that provide food, community, and health benefits, but gardens often are non-permanent due to development and green space loss. Thus, investigating their significance and benefit across urban regions is critical for research and policy alike. This study investigated the role of community gardens in providing human well-being benefits across three counties in the California Central Coast—a region undergoing massive urban transformation in the last century. We measured how multiple aspects of self-reported gardener well-being varied in relation to the social opportunities of surrounding neighborhoods and the biophysical features of the landscapes in which the gardens were embedded. The results document improvements in gardener well-being through gardening across social and biophysical gradients. Gardeners are motivated by diverse reasons, varying from gardening in order to connect to nature, to gardening for improved food access, or to enhance time spent with family. Community gardens are therefore important for supporting many well-being benefits. Policies to maintain and protect gardens should prioritize neighborhoods with needs for connecting to nature and enhancing social interaction within the community.

Restoring and conserving rare native ecosystems: A 14-year plantation removal experiment

Forest plantations occupy 2% of Earth's land surface and are increasingly important in biological conservation both through their establishment and removal. To restore conservation-priority oak savannas and prairies in the Midwestern United States, we began a conifer plantation removal experiment in northwestern Ohio in 2002 and measured plant community response, including nectar plants for conservation-priority invertebrates, during a 14-year period. Oak (Quercus) trees, crucial to restoring savanna structure, only became established on plots where conifers were cut. In the understory, native species richness/0.05ha was 34–50% higher on plots where conifers were cut than on control plots in uncut plantations. By year 14, cut plots accrued 13 species with high coefficients of conservatism (specialist species typifying high-quality natural habitats) and 10 state-listed rare species; uncut plantations did not contain any such species. With 71 wetland species detected during the experiment (out of 370 total plant species), only cut plots developed a wetland-upland biophysical gradient diagnostic of diverse Midwestern savanna-prairie landscapes. Between year 1 and 14 after plantation cutting, cover of nectar plants utilized by federally endangered Karner blue butterflies (Lycaeides melissa samuelis) doubled, while cover of these plants remained negligible in uncut plantations. Similarly, cover of plants utilized by bees increased by 24× after plantation cutting. Cutting plantations rapidly and persistently benefited native species for at least 14years, with minimal increase in non-native plants.

Abstract A43: Interfacial migration patterns in glioblastoma are analyzed in structured hydrogel platforms

Abstract Glioblastoma multiforme (GBM) is one of the deadliest forms of brain cancer (median survival time of 12-15 months). Since the cancer is unique in its ability to invade diffusely into the surrounding brain tissue, surgical resection is often ineffective. As such, it is imperative to develop methods of understanding GBM behavior and determining novel therapeutic strategies. Currently, there are limited tools to rigorously assess the relationship between the tissue microenvironment, tumor growth and invasion, and therapeutic outcomes. While most invasion studies have utilized 2D substrates or semi-3D chambers, the lack of cell-cell/cell-matrix interactions limits the ability to accurately predict GBM invasive behavior as observed in a 3D tumor environment. GBM cell invasion is influenced by mechanical and chemical heterogeneity within the extracellular matrix (ECM). The presence of hyaluronic acid (HA) and the differences in stiffness within the brain parenchyma contribute to invasive phenotype. Vasculature within the ECM has also been shown to affect the invasive behavior of GBM, as cells migrating along vascular beds experience integrin signaling through proteins in the vascular basement membrane. To understand how these multiple signals regulate GBM cell invasion, we have developed a 3D methacrylamide-functionalized gelatin (GelMA) hydrogel platform that allows for selective incorporation of matrix-immobilized HA as inspired by the varying composition and structure of brain parenchyma. This system can be further modified to incorporate structural, biophysical, and metabolic gradients inspired by GBM tumor margins and the native brain microenvironment. We developed an in vitro invasion assay utilizing GBM cell-coated dextran beads embedded into the hydrogels to effectively characterize GBM invasive phenotype as a function of margin-inspired variations in matrix stiffness and composition within the hydrogels. A family of hydrogels with varying stiffness and variants of matrix-bound HA were explored with the invasion assay. Experiments were conducted using GBM cell line U251, which is known to be highly invasive. Preliminary data showed that stiffness and HA content did not influence cell metabolic activity. Not surprisingly, we saw a significant increase in cell invasion distance in softer hydrogels compared to their stiffer counterparts. Interestingly, cells invaded less in hydrogels with HA than in those containing GelMA only. ELISA showed a higher secretion of soluble HA in GelMA-only hydrogels, which may be due to the necessity of cells to compensate for the lack of bound HA, thereby resulting in a more invasive behavior. Recent efforts have focused on the development of vessel structures within these hydrogels by using a co-culture of human umbilical vein endothelial cells (HUVECs) and normal human lung fibroblasts (NHLFs). The incorporation of vasculature will offer an additional level of complexity to the platform to study cell migration mechanisms in GBM. Preliminary experiments demonstrated that following seven- and ten-day culture periods, the vessel architectures were stable between time points. Vessel development, as measured with metrics such as vessel area, vessel length, and number of junction, was observed more robustly in hydrogels without HA. We conclude that our platform is capable of promoting differential invasive behavior of GBM cells in response to heterogeneous mechanical and chemical properties, and that our platform shows the potential to probe tumor-vessel interactions. In future work, we intend to elucidate how vessel structures, when combined with varying matrix stiffness and HA content, impact GBM invasive behavior within the tumor microenvironment. We predict that more invasive phenotype and more established migratory trajectories will be observed in the presence of vessel structures within the hydrogels. Citation Format: Jee-Wei Emily Chen, Mai Ngo, Brendan Harley. Interfacial migration patterns in glioblastoma are analyzed in structured hydrogel platforms. [abstract]. In: Proceedings of the AACR Special Conference on Engineering and Physical Sciences in Oncology; 2016 Jun 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2017;77(2 Suppl):Abstract nr A43.

Snowlines and Treelines in the Tropical Andes

Examination of the dynamism of snowlines and treelines could provide insights into environmental change processes affecting land cover in the tropical Andes Mountains. Further, land cover at these ecotones represents a powerful lens through which to monitor and understand ecological processes across biophysical gradients while acknowledging their socioenvironmental dimensions. To illustrate this approach, we draw on recent research from two sites in the high tropical Andes where, at the regional scale, land cover assessments document retreating glaciers and changing amounts of forest cover, even though steep topographic gradients impose spatial shifts at much finer scales. Our results show that heterogeneous patterns of glacier recession open up new ecological spaces for plant colonization, potentially forming new grasslands, shrublands, and wetlands. In addition, treeline shifts are tied to changes in woody plant dominance, which can vary in rate and pattern as a result of aspect, past land use, and current livelihoods. We suggest that the telecoupling of regional and global biophysical and socioeconomic drivers of land use and land cover change to specific landscape combinations of elevation, aspect, and slope position might explain much of the spatial heterogeneity that characterizes landscape stasis and flux in mountains.

Biophysical Characterization of Protected Areas Globally through Optimized Image Segmentation and Classification

Protected areas (PAs) need to be assessed systematically according to biodiversity values and threats in order to support decision-making processes. For this, PAs can be characterized according to their species, ecosystems and threats, but such information is often difficult to access and usually not comparable across regions. There are currently over 200,000 PAs in the world, and assessing these systematically according to their ecological values remains a huge challenge. However, linking remote sensing with ecological modelling can help to overcome some limitations of conservation studies, such as the sampling bias of biodiversity inventories. The aim of this paper is to introduce eHabitat+, a habitat modelling service supporting the European Commission’s Digital Observatory for Protected Areas, and specifically to discuss a component that systematically stratifies PAs into different habitat functional types based on remote sensing data. eHabitat+ uses an optimized procedure of automatic image segmentation based on several environmental variables to identify the main biophysical gradients in each PA. This allows a systematic production of key indicators on PAs that can be compared globally. Results from a few case studies are illustrated to show the benefits and limitations of this open-source tool.

Biodiversity and agriculture in dynamic landscapes: Integrating ground and remotely-sensed baseline surveys

Sustainable biodiversity and land management require a cost-effective means of forecasting landscape response to environmental change. Conventional species-based, regional biodiversity assessments are rarely adequate for policy planning and decision making. We show how new ground and remotely-sensed survey methods can be coordinated to help elucidate and predict relationships between biodiversity, land use and soil properties along complex biophysical gradients that typify many similar landscapes worldwide. In the lower Zambezi valley, Mozambique we used environmental, gradient-directed transects (gradsects) to sample vascular plant species, plant functional types, vegetation structure, soil properties and land-use characteristics. Soil fertility indices were derived using novel multidimensional scaling of soil properties. To facilitate spatial analysis, we applied a probabilistic remote sensing approach, analyzing Landsat 7 satellite imagery to map photosynthetically active and inactive vegetation and bare soil along each gradsect. Despite the relatively low sample number, we found highly significant correlations between single and combined sets of specific plant, soil and remotely sensed variables that permitted testable spatial projections of biodiversity and soil fertility across the regional land-use mosaic. This integrative and rapid approach provides a low-cost, high-return and readily transferable methodology that permits the ready identification of testable biodiversity indicators for adaptive management of biodiversity and potential agricultural productivity.

To what extent could edge effects and habitat fragmentation diminish the potential benefits of land sparing?

Land sharing and land sparing are contrasting proposals for minimising the impacts of agriculture on wild species. Edge effects (biophysical gradients near habitat boundaries) might reduce population sizes on spared land, particularly in highly-fragmented landscapes, so might change conclusions about whether land sparing or land sharing is better for species' persistence. We assessed this possibility by modelling the population sizes of 120 Ghanaian bird species in the presence of a range of hypothetical edge effects under land-sparing and land-sharing strategies, and at different levels of habitat fragmentation and agricultural production. We found that edge effects can reduce population densities on spared land, and in highly-fragmented landscapes can – at modest levels of agricultural production combined with high edge penetration distances – cause the optimal strategy to switch from land sparing to land sharing. Nevertheless, land sparing maximised population sizes for more species in most cases tested. This conclusion was best supported for sensitive species with small global geographical ranges, which are likely to include those of greatest future conservation concern. The size of patches of spared land affected conservation outcomes: population sizes were maximised under a land-sparing strategy that spared large blocks of natural habitat of ~1000 or, better, ~10,000ha. To effect land sparing in practice would require policies that promoted both increases in agricultural yield and the establishment or protection of natural habitats on spared land. Because the optimum scale of patches of spared land for edge-sensitive species is generally larger than the size of individual farms, policies that facilitate coordinated action by farmers or other land managers might be required.

Towards catchment classification in data‐scarce regions

AbstractAssessing spatial variation in hydrologic processes can help to inform freshwater management and advance ecological understanding, yet many areas lack sufficient flow records on which to base classifications. Seeking to address this challenge, we apply concepts developed in data‐rich settings to public, global data in order to demonstrate a broadly replicable approach to characterizing hydrologic variation. The proposed approach groups the basins associated with reaches in a river network according to key environmental drivers of hydrologic conditions. This initial study examines Colorado (USA), where long‐term streamflow records permit comparison with previously distinguished flow regime types, and Ecuador, where data limitations preclude such analysis. The flow regime types assigned to gages in Colorado corresponded reasonably well to the classes distinguished from environmental features. The divisions in Ecuador reflected major known biophysical gradients while also providing a higher resolution supplement to an existing depiction of freshwater ecoregions. Although freshwater policy and management decisions occur amidst uncertainty and imperfect knowledge, this classification framework offers a rigorous and transferrable means to distinguish catchments in data‐scarce regions. The maps and attributes of the resulting ecohydrologic classes offer a departure point for additional study and data collection programmes such as the placement of stations in under‐monitored classes, and the divisions may serve as a preliminary template with which to structure conservation efforts such as environmental flow assessments. Copyright © 2015 John Wiley & Sons, Ltd.

Factors influencing incidental representation of previously unknown conservation features in marine protected areas.

Spatially explicit information on species distributions for conservation planning is invariably incomplete; therefore, the use of surrogates is required to represent broad-scale patterns of biodiversity. Despite significant interest in the effectiveness of surrogates for predicting spatial distributions of biodiversity, few researchers have explored questions involving the ability of surrogates to incidentally represent unknown features of conservation interest. We used the Great Barrier Reef marine reserve network to examine factors affecting incidental representation of conservation features that were unknown at the time the reserve network was established. We used spatially explicit information on the distribution of 39 seabed habitats and biological assemblages and the conservation planning software Marxan to examine how incidental representation was affected by the spatial characteristics of the features; the conservation objectives (the minimum proportion of each feature included in no-take areas); the spatial configuration of no-take areas; and the opportunity cost of conservation. Cost was closely and inversely correlated to incidental representation. However, incidental representation was achieved, even in a region with only coarse-scale environmental data, by adopting a precautionary approach that explicitly considered the potential for unknown features. Our results indicate that incidental representation is enhanced by partitioning selection units along biophysical gradients to account for unknown within-feature variability and ensuring that no-take areas are well distributed throughout the region; by setting high conservation objectives that (in this case >33%) maximize the chances of capturing unknown features incidentally; and by carefully considering the designation of cost to planning units when using decision-support tools for reserve design. The lessons learned from incidental representation in the Great Barrier Reef have implications for conservation planning in other regions, particularly those that lack detailed environmental and ecological data.

Assessing MODIS Land Cover Products over China with Probability of Interannual Change

AbstractAccurate and up-to-date land cover data are important for climate-change modeling. Quality assessment is becoming critical, as many satellite-based land cover products of differing scales have been released to meet the needs of scientific studies. In this study, the authors assessed the Moderate Resolution Imaging Spectroradiometer (MODIS) land cover products by analyzing the probability of interannual change from 2001 to 2012. The authors found that, cumulatively, 43.0% of MODIS land cover had changed over China from 2001 to 2012 at least once. Of this percentage, 12.1% was considered unreasonable change, 6.1% was considered reasonable change, and areas of confusion accounted for about 24.8%, giving rise to great uncertainty in the products. MODIS Collection 51 products clearly have less uncertainty than the Collection 5 products. Areas of reasonable change occurred in transition zones of ecological, biophysical, and climate gradients, while areas of unreasonable change appeared in heterogeneous ...

Forest change over 155 years along biophysical gradients of forest composition, environment, and anthropogenic disturbance

Understanding temporal forest change across spatial biophysical gradients is fundamental to managing dynamic forests across variable landscapes. This is especially true for identifying how biophysical variation mediates forest development through multi-century changes in climate and eras of forest manipulation by humans. We examined 155years of forest change across a 13,000-ha mixed conifer landscape in the Spring Mountains, Nevada, USA. We reconstructed forest composition at 31 sites in 1855 (pre-Euro-American settlement, and near the end of the Little Ice Age), 1881 (logging era), 1900 (before establishment of government forest reserve), 1950 (mid-century fire exclusion), and 2009 (present forest). Differing from many other western conifer landscapes, density of large trees (>50cm in diameter) increased through time. Aside from large trees and one measure of species compositional change, five other measures of forest change (e.g., percent difference in tree density) were spatially variable across the landscape and not well represented by ‘average’ change in the study area. Forest composition in 1855 minimally influenced the next 155years of forest change. In contrast, the amount, timing, and direction of forest change were linked with topographic gradients. Forests on warm slope aspects incurred the least amount of change, which also was delayed in time, whereas forests on cooler aspects already appreciably changed by 1900. Warm aspects were the only ones to lose trees during the most recent 60-year period (1950–2009), with a decline in median tree density of 13%, compared to continued gains on moister sites. Management applications of this spatio-temporal variation include anchoring fuel treatments around areas of open, little-changed forest to increase effective size of treatments.

Context‐dependent effects on spatial variation in deer‐vehicle collisions

Identifying factors that contribute to the risk of wildlife‐vehicle collisions (WVCs) has been a key focus of wildlife managers, transportation safety planners and road ecologists for over three decades. Despite these efforts, few generalities have emerged which can help predict the occurrence of WVCs, heightening the uncertainty under which conservation, wildlife and transportation management decisions are made. Undermining this general understanding is the use of study area boundaries that are incongruent with major biophysical gradients, inconsistent data collection protocols among study areas and species‐specific interactions with roads. We tested the extent to which factors predicting the occurrence of deer‐vehicle collisions (DVCs) were general among five study areas distributed over a 11,400‐km2 region in the Canadian Rocky Mountains. In spite of our system‐wide focus on the same genus (i.e., Odocoileus hemionus and O. virginianus), study area delineation along major biophysical gradients, and use of consistent data collection protocols, we found that large‐scale biophysical processes influence the effect of localized factors. At the local scale, factors predicting WVC occurrence varied greatly between individual study areas. Distance to water was an important predictor of WVCs in three of the five study areas, while other variables had modest importance in only two of the five study areas. Thus, lack of generality in factors predicting WVCs may have less to do with methodological or taxonomic differences among study areas than the large‐scale, biophysical context within which the data were collected. These results highlight the critical need to develop a conceptual framework in road ecology that can unify the disparate results emerging from field studies on WVC occurrence.

Regional-scale application of lidar: Variation in forest canopy structure across the southeastern US

Canopy structure is a fundamental property of forest ecosystems that influences microclimate, runoff, decomposition, nutrient cycling, forest disturbance, carbon storage, and biodiversity. Unlike ecosystem properties such as vegetation production, canopy structure mapping is limited by measurement constraints and is primarily measured for small areas. Consequently, few large scale studies of carbon budgets, nutrient cycling, and biodiversity use quantitative data on canopy structure. Progress in broad scale mapping of canopy structure has recently been made by merging field, airborne lidar, and satellite data. As a step towards regional mapping of canopy structure with lidar and satellite data, we examine patterns of lidar-derived canopy structure across five ecoregions from Maryland to Mississippi and evaluate relationships with climate, topography, and soils. We used NASA’s Laser Vegetation Imaging Sensor (LVIS) to quantify canopy height, canopy cover, diversity of cover, and upper and lower canopy ratio metric along a 4000-km transect. Controlling for stand age, we found that canopy structure varied among undisturbed, closed-canopy stands across the study area. Compared with the Southeast Plains Ecoregion, the Blue Ridge and Central Appalachians ecoregions were greater in canopy height (25%), canopy cover (18%), and cover in the upper third of the canopy (212%). Values in the Piedmont were similar to those in the Southeast Plains. Locations highest in canopy structure were intermediate in temperature, growing season precipitation, topographic complexity and were located on sandy soils. The strength of biophysical models differed among ecoregions, explaining 13% of the variation in canopy height in the Southeastern Plain to 60% in the Ridge and Valley Ecoregion. Canopy structure also differed among disturbance classes. Undisturbed forests were 30% higher in canopy height, 15% higher in canopy cover, and 18% higher in cover of the upper third of the canopy than disturbed forests. Managed pine plantations were intermediate in canopy structure between disturbed and undisturbed forests. This study demonstrates that airborne lidar data can be used to distinguish differences in canopy structure among undisturbed forests in varying biophysical settings and between undisturbed and disturbed forests across sub-continental transects. The results suggest that airborne lidar data in conjunction with data on biophysical gradients can be used as a basis for extrapolating canopy structure at fine spatial scales across regional extents. This would allow for fine-scale characterization of forest structure continuously across large regions. Such methods should allow breakthroughs in the use of canopy structure in ecosystem management and global change studies.

From principles to practice: a spatial approach to systematic conservation planning in the deep sea

Increases in the demand and price for industrial metals, combined with advances in technological capabilities have now made deep-sea mining more feasible and economically viable. In order to balance economic interests with the conservation of abyssal plain ecosystems, it is becoming increasingly important to develop a systematic approach to spatial management and zoning of the deep sea. Here, we describe an expert-driven systematic conservation planning process applied to inform science-based recommendations to the International Seabed Authority for a system of deep-sea marine protected areas (MPAs) to safeguard biodiversity and ecosystem function in an abyssal Pacific region targeted for nodule mining (e.g. the Clarion-Clipperton fracture zone, CCZ). Our use of geospatial analysis and expert opinion in forming the recommendations allowed us to stratify the proposed network by biophysical gradients, maximize the number of biologically unique seamounts within each subregion, and minimize socioeconomic impacts. The resulting proposal for an MPA network (nine replicate 400 × 400 km MPAs) covers 24% (1 440 000 km(2)) of the total CCZ planning region and serves as example of swift and pre-emptive conservation planning across an unprecedented area in the deep sea. As pressure from resource extraction increases in the future, the scientific guiding principles outlined in this research can serve as a basis for collaborative international approaches to ocean management.

Spatial drivers of ecosystem structure and function in a floodplain riverscape: springbrook nutrient dynamics

On riverine flood plains, reorganization by fluvial processes creates and maintains a mosaic of aquatic and riparian landscape elements across a biophysical gradient of disturbance and succession. Across flood plains of gravel-bottom rivers, spring brooks emerge from points of groundwater discharge that may occur in distinct landscape positions. We investigated how ecosystem processes in spring brooks differ spatially across biophysical zones, reflecting how landscape position dictates severity of flood disturbance, allochthonous loading from riparian forests, and inputs from groundwater systems. Between July and October 2011, we quantified aspects of ecosystem structure and function among 6 spring brooks of the Nyack flood plain, Flathead River, Montana. Structural features varied predictably across near-channel (i.e., parafluvial) and late successional (i.e., orthofluvial) biophysical zones. Large wood standing stocks increased >40× (0.19–9.19 kg/m2), dominant particle size class differed by an order of magnitude (median particle size [D50] = 2–27), and measures of vertical hydraulic gradient (–0.06 to +0.12 cm/cm) reflected differences in landscape position. We found fine sediment accumulation, stronger groundwater inputs, and greater benthic and large wood standing stocks in orthofluvial than in parafluvial spring brooks. Algal biomass was negatively correlated with insolation and positively related to vertical hydraulic gradient. Results from microcosm experiments showed increasing N uptake across the gradient from parafluvial to orthofluvial spring brooks. Functional response to landscape-scale organization of springbrook structure underscores the need for a spatially explicit model of floodplain ecology.

Woodland Dynamics at the Northern Range Periphery: A Challenge for Protected Area Management in a Changing World

Managers of protected natural areas increasingly are confronted with novel ecological conditions and conflicting objectives to preserve the past while fostering resilience for an uncertain future. This dilemma may be pronounced at range peripheries where rates of change are accelerated and ongoing invasions often are perceived as threats to local ecosystems. We provide an example from City of Rocks National Reserve (CIRO) in southern Idaho, positioned at the northern range periphery of pinyon-juniper (P-J) woodland. Reserve managers are concerned about P-J woodland encroachment into adjacent sagebrush steppe, but the rates and biophysical variability of encroachment are not well documented and management options are not well understood. We quantified the rate and extent of woodland change between 1950 and 2009 based on a random sample of aerial photo interpretation plots distributed across biophysical gradients. Our study revealed that woodland cover remained at approximately 20% of the study area over the 59-year period. In the absence of disturbance, P-J woodlands exhibited the highest rate of increase among vegetation types at 0.37% yr−1. Overall, late-successional P-J stands increased in area by over 100% through the process of densification (infilling). However, wildfires during the period resulted in a net decrease of woody evergreen vegetation, particularly among early and mid-successional P-J stands. Elevated wildfire risk associated with expanding novel annual grasslands and drought is likely to continue to be a fundamental driver of change in CIRO woodlands. Because P-J woodlands contribute to regional biodiversity and may contract at trailing edges with global warming, CIRO may become important to P-J woodland conservation in the future. Our study provides a widely applicable toolset for assessing woodland ecotone dynamics that can help managers reconcile the competing demands to maintain historical fidelity and contribute meaningfully to the U.S. protected area network in a future with novel, no-analog ecosystems.

Assessment of landscape patterns affecting land surface temperature in different biophysical gradients in Shenzhen, China

The urban heat island (UHI) effect is one of the important ecological effects of urbanization. This study focuses on the different effects of landscape patterns on LST within different land covers. The land cover was measured by surface biophysical components, including vegetation fraction (VF) and impervious surface area (ISA), acquired by a linear spectral mixture model (LSMM). LST was derived from Landsat-5 TM thermal infrared (TIR) data using the generalized single-channel method. Landscape patterns were measured by landscape metrics, including the Shannon diversity index (SHDI), the aggregation index (AI), patch density (PD), and fractal dimension area-weighted mean index (FRAC_AM). Shenzhen, a rapidly urbanizing city in China, was taken as the case study area. Results showed that VF and ISA are more important than spatial patterns in determining LST. However, these effects change in densely covered areas. VF and LST are negatively correlated, with the inflection of the regression curves being 45 %. In areas with VF lower than 45 %, the correlation between LST and VF is monotonically linear. In areas with VF higher than 45 %, landscape patterns can act to decrease LST. The aggregation index (AI) and the largest patch index (LPI) can contribute to decreasing LST significantly. Impervious surfaces contribute to high temperature, and the inflection point of the regression curves is 70 %. In areas with ISA higher than 70 %, a fragmented pattern of impervious surfaces can lower LST. These findings provide insights for planners into how the strategic use of landscape to mitigate UHI effects may vary for different land covers.

Patterns and drivers ofAraucaria araucanaforest growth along a biophysical gradient in the northern Patagonian Andes: Linking tree rings with satellite observations of soil moisture

Araucaria araucana (Araucaria) is a long-lived conifer growing along a sharp west–east biophysical gradient in the Patagonian Andes. The patterns and climate drivers of Araucaria growth have typically been documented on the driest part of the gradient relying on correlations with meteorological records, but the lack of in situ soil moisture observations has precluded an assessment of the growth responses to soil moisture variability. Here, we use a network of 21 tree-ring width chronologies to investigate the spatiotemporal patterns of tree growth through the entire gradient and evaluate their linkages with regional climate and satellite-observed surface soil moisture variability. We found that temporal variations in tree growth are remarkably similar throughout the gradient and largely driven by soil moisture variability. The regional spatiotemporal pattern of tree growth was positively correlated with precipitation (r = 0.35 for January 1920–1974; P < 0.01) and predominantly negatively correlated with temperature (r = −0.38 for January–March 1920–1974; P < 0.01) during the previous growing season. These correlations suggest a temporally lagged growth response to summer moisture that could be associated with known physiological carry-over processes in conifers and to a response to moisture variability at deeper layers of the rooting zone. Notably, satellite observations revealed a previously unobserved response of Araucaria growth to summer surface soil moisture during the current rather than the previous growing season (r = 0.65 for 1979–2000; P < 0.05). This new response has a large spatial footprint across the mid-latitudes of the South American continent (35°–45°S) and highlights the potential of Araucaria tree rings for palaeoclimatic applications. The strong moisture constraint on tree growth revealed by satellite observations suggests that projected summer drying during the coming decades may result in regional growth declines in Araucaria forests and other water-limited ecosystems in the Patagonian Andes.