Showing papers in "Ecological processes in 2013"

Fine-scale hydrologic modeling for regional landscape applications: the California Basin Characterization Model development and performance

Abstract: Resource managers need spatially explicit models of hydrologic response to changes in key climatic drivers across variable landscape conditions We demonstrate the utility of a Basin Characterization Model for California (CA-BCM) to integrate high-resolution data on physical watershed characteristics with historical or projected climate data to predict watershed-specific hydrologic responses The CA-BCM applies a monthly regional water-balance model to simulate hydrologic responses to climate at the spatial resolution of a 270-m grid The model has been calibrated using a total of 159 relatively unimpaired watersheds for the California region As a result of calibration, predicted basin discharge closely matches measured data for validation watersheds The CA-BCM recharge and runoff estimates, combined with estimates of snowpack and timing of snowmelt, provide a basis for assessing variations in water availability Another important output variable, climatic water deficit, integrates the combined effects of temperature and rainfall on site-specific soil moisture, a factor that plants may respond to more directly than air temperature and precipitation alone Model outputs are calculated for each grid cell, allowing results to be summarized for a variety of planning units including hillslopes, watersheds, ecoregions, or political boundaries The ability to confidently calculate hydrologic outputs at fine spatial scales provides a new suite of hydrologic predictor variables that can be used for a variety of purposes, such as projections of changes in water availability, environmental demand, or distribution of plants and habitats Here we present the framework of the CA-BCM model for the California hydrologic region, a test of model performance on 159 watersheds, summary results for the region for the 1981–2010 time period, and changes since the 1951–1980 time period

On the role of traditional ecological knowledge as a collaborative concept: a philosophical study

Abstract: The concept of traditional ecological knowledge (TEK), along with synonymous or closely related terms like indigenous knowledge and native science, has some of its origins in literatures on international development and adaptive management. There is a tendency to want to determine one definition for TEK that can satisfy every stakeholder in every situation. Yet a scan of environmental science and policy literatures reveals there to be differences in definitions that make it difficult to form a consensus. What should be explored instead is the role that the concept of TEK plays in facilitating or discouraging cross-cultural and cross-situational collaboration among actors working for indigenous and non-indigenous institutions of environmental governance, such as tribal natural resources departments, federal agencies working with tribes, and co-management boards. This is a philosophical paper that explores how the concept of TEK is defined in science and policy literatures and what purpose it serves for improving cooperative environmental and natural resources stewardship and management between indigenous and non-indigenous institutions. The philosophical method applied here is one that outlines numerous possible meanings of a concept (TEK, in this paper) and the implications of each meaning for science and policy. In science and policy literatures, there are different definitions of TEK. Controversy can brew over TEK when people hold definitions that are based on different assumptions. There are two kinds of assumptions about the meaning of TEK. The first kind refers to assumptions about the mobilization of TEK, or what I call knowledge mobilization. The second kind involves assumptions about how to understand the relationship between TEK and disciplines like ecology or biology, or, in other words, the relation between TEK and science. Different positions that fall under the two kinds of assumptions (knowledge mobilization; TEK and science) can generate disagreements because they imply differences about “whose” definition of TEK gets privileged, who is counted as having expert authority over environmental governance issues, and how TEK should be factored into policy processes that already have a role for disciplines like forestry or toxicology in them. In light such disagreements, I argue that the concept of TEK should be understood as a collaborative concept. It serves to invite diverse populations to continually learn from one another about how each approaches the very question of “knowledge” in the first place, and how these different approaches can be blended to better steward natural resources and adapt to climate change. The implication is that environmental scientists and policy professionals, indigenous and non-indigenous, should not be in the business of creating definitions of TEK. Instead, they should focus more on creating long term processes that allow the different implications of approaches to knowledge in relation to stewardship goals to be responsibly thought through.

Indigenous marine resource management on the Northwest Coast of North America

Abstract: There is increasing recognition among anthropologists that indigenous peoples of the Northwest Coast actively managed their terrestrial and marine resources and ecosystems. Such management practices ensured the ongoing productivity of valued resources and were embedded in a complex web of socio-economic interactions. Using ethnographic and archaeological data, this paper synthesizes the ecological and cultural aspects of marine management systems of coastal First Nations. We divide our discussion into four aspects of traditional management systems: harvesting methods, enhancement strategies, tenure systems, and worldview and social relations. The ethnographic data, including memories of living knowledge holders, tend to provide windows into daily actions and the more intangible aspects of management; the archaeological record provides insights into the more tangible aspects and how management systems developed through time and space. This review demonstrates not only the breadth of Northwest Coast marine management but also the value of integrating different kinds of knowledge and data to more fully document the whole of these ancient management systems.

Fluxes of water, sediments, and biogeochemical compounds in salt marshes

Abstract: Tidal oscillations systematically flood salt marshes, transporting water, sediments, organic matter, and biogeochemical elements such as silica. Here we present a review of recent studies on these fluxes and their effects on both ecosystem functioning and morphological evolution of salt marshes. We reexamine a simplified model for the computation of water fluxes in salt marshes that captures the asymmetry in discharge between flood and ebb. We discuss the role of storm conditions on sediment fluxes both in tidal channels and on the marsh platform. We present recent methods and field instruments for the measurement of fluxes of organic matter. These methods will provide long-term data sets with fine temporal resolution that will help scientists to close the carbon budget in salt marshes. Finally, the main processes controlling fluxes of biogenic and dissolved silica in salt marshes are explained, with particular emphasis on the uptake by marsh macrophytes and diatoms.

Adopting novel ecosystems as suitable rehabilitation alternatives for former mine sites

Abstract: The nature and extent of environmental disturbance associated with mining commonly entails completely new and challenging combinations of climate, lithology and landform. Consequently, the outcomes of ecological processes associated with the recovery or restoration of ecosystems cannot be predicted reliably from previously known associations between their physical and biological components. For radically disturbed sites, we propose that it is not practicable to aim for the restoration of historical ecosystems. However, hybrid (reversibly different) or novel (irreversibly different) ecosystems comprising new combinations of physical and biological components, including both native and non-native species, could provide levels of stability and functionality acceptable to all stakeholders and within feasible management regimes. We propose that limiting physical conditions of the landscape can be identified and managed, and that alternative species combinations for introduction to these new landscapes may be considered with cautious optimism.

Incorporating novelty and novel ecosystems into restoration planning and practice in the 21st century

Abstract: Novelty pervades the biosphere. In some cases, potentially irreversible abiotic and/or biotic changes have led to the crossing of thresholds and thus the formation of “novel ecosystems.” Their widespread emergence (particularly on land) and the presence of continued environmental change challenge a traditional restoration goal of restoring an historical ecosystem. Instead, we argue that restoration could broaden its frame of reference to consider how novel ecosystems might be used to maintain global biodiversity and provide ecosystem services and, in doing so, save potentially wasted efforts in attempting to fulfil traditional goals. Here we explore this contention in more depth by addressing: Are novel ecosystems innovative planning or lowering the bar? We show that novel ecosystems were not innovative planning in their original conception. On the contrary, they were recognized as ecosystems that were recalcitrant to traditional restoration approaches, coupled with an awareness that they had arisen inadvertently through deliberate human activity, either on- or off-site. Their recalcitrance to traditional restoration suggests that alternative goals may exist for these ecosystems using sometimes innovative intervention. This management may include biodiversity conservation or restoration for ecological function. We elucidate the latter aspect with reference to an experiment in the wheatbelt of Western Australia—The Ridgefield Multiple Ecosystem Services Experiment—the design of which has been informed by ecological theory and the acceptance of novelty as an ecosystem component. Although novel ecosystems do provide opportunities to broaden restoration planning and practice, and ultimately maintain and conserve global biodiversity in this era of environmental change, they necessarily “lower the bar” in restoration if the bar is considered to be the historical ecosystem. However, in these times of flux, such a bar is increasingly untenable. Instead, careful and appropriate interventions are required at local, regional, and global scales. These interventions need to take history into account, use ecological and evolutionary theory to inform their design, and be mindful of valid concerns such as hubris. Careful interventions thus provide an opportunity for broadening restoration’s framework to focus on maintaining global biodiversity and delivering ecosystem services as well as the traditional goals of restoring historical ecosystems.

Denitrification from nitrogen-fixing biologically crusted soils in a cool desert environment, southeast Utah, USA

Abstract: Nitrogen fixation by microorganisms within biological soil crust (“biocrust”) communities provides an important pathway for N inputs in cool desert environments where soil nutrients are low and symbiotic N-fixing plants may be rare. Estimates of N fixation in biocrusts often greatly exceed that of N accretion rates leading to uncertainty regarding N loss pathways. In this study we examined nitrogen fixation and denitrification rates in biocrust communities that differed in N fixation potential (low N fixation = light cyanobacterial biocrust, high N fixation = dark cyanolichen crust) at four temperature levels (10, 20, 30, 40°C) and four simulated rainfall levels (0.05, 0.2, 0.6, 1 cm rain events) under controlled laboratory conditions. Acetylene reduction rates (AR, an index of N fixation activity) were over six-fold higher in dark crusts relative to light crusts. Dark biocrusts also exhibited eight-fold higher denitrification rates. There was no consistent effect of temperature on denitrification rates, but there was an interactive effect of water addition and crust type. In light crusts, denitrification rates increased with increasing water addition, whereas the highest denitrification rates in dark crusts were observed at the lowest level of water addition. These results suggest that there are no clear and consistent environmental controls on short-term denitrification rates in these biologically crusted soils. Taken together, estimates of denitrification from light and dark biocrusts constituted 3 and 4% of N fixation rates, respectively suggesting that losses as denitrification are not significant relative to N inputs via fixation. This estimate is based on a previously published conversion ratio of ethylene produced to N fixed that is low (0.295), resulting in high estimates of N fixation. If future N fixation studies in biologically crusted soils show that these ratios are closer to the theoretical 3:1 ratio, denitrification may constitute a more significant loss pathway relative to N fixed.

Early life on land and the first terrestrial ecosystems

Abstract: Terrestrial ecosystems have been largely regarded as plant-dominated land surfaces, with the earliest records appearing in the early Phanerozoic ( 3,400 Ma-old paleosols endorses the idea that life on land perhaps occurred in parallel with aquatic life back in the Paleoarchean. The rapid adaptations seen in modern terrestrial microbes, their outstanding tolerance to extreme and fluctuating conditions, their early and rapid diversification, and their old fossil record collectively suggest that they constituted the earliest terrestrial ecosystems, at least since the Neoarchean, further succeeding on land and forming a biomass-rich cover with mature soils where plant-dominated ecosystems later evolved. Understanding how life diversified and adapted to non-aquatic conditions from the actualistic and paleontological perspective is critical to understanding the impact of life on the Earth’s systems over thousands of millions of years.

Novel ecosystems created by coal mines in central Queensland’s Bowen Basin

Abstract: Open-cut coal mining began in central Queensland’s Bowen Basin approximately 50 years ago. Over this period of time, mine rehabilitators have used a variety of tree, shrub, and groundcover species to create ‘novel ecosystems’ to stabilise soils and provide vegetative cover for pre-supposed final end-land uses. We examine post-mining rehabilitation from multiple soil and vegetation monitoring activities in the Bowen Basin to assess the similarity of landforms, plant composition, and trends in plant diversity compared to unmined reference communities. Rehabilitated spoil dumps and reference sites were assessed using soil and vegetation data contained in compliance monitoring reports from Goonyella Riverside, Moura, Oaky Creek, Rolleston, and Blackwater mines. Slopes, soil chemistry, and plant species mixes of rehabilitation aged from 2 to 22 years were compared to selected reference communities. Mines in this region have generally proposed one of two post-rehabilitation end-land uses: either pasture for cattle grazing or reconstructed native communities which potentially provide native fauna habitat. Landform data from a selection of these mine sites suggest that when their rehabilitation was compared to nearby reference sites median slope values were between 2.5 and 7 times steeper and soil pH, electrical conductivity, and phosphorus levels were significantly higher. The steeply sloped landforms, poor soil characteristics, depauperate native species pool, and uniform presence of exotic pasture grasses in the rehabilitation indicate that most of these newly created ecosystems should not be used for cattle grazing and also have few natural values. Legislative and community expectations have changed progressively over time and, although much of the rehabilitation is currently dominated by an assemblage of exotic buffel grass (Cenchrus ciliaris) and Acacia spp., recent environmental authorities suggest these ‘novel ecosystems’ will be judged against native reference sites. Upon completion of mining activities the resilience of these new ecosystems to drought, fire, and grazing will need to be demonstrated prior to lease relinquishment.

Using strategically applied grazing to manage invasive alien plants in novel grasslands

Abstract: Novel ecosystems that contain new combinations of invasive alien plants (IAPs) present a challenge for managers. Yet, control strategies that focus on the removal of the invasive species and/or restoring historical disturbance regimes often do not provide the best outcome for long-term control of IAPs and the promotion of more desirable plant species. This study seeks to identify the primary drivers of grassland invasion to then inform management practices toward the restoration of native ecosystems. By revisiting both published and unpublished data from experiments and case studies within mainly an Australian context for native grassland management, we show how alternative states models can help to design control strategies to manage undesirable IAPs by manipulating grazing pressure. Ungulate grazing is generally considered antithetical to invasive species management because in many countries where livestock production is a relatively new disturbance to grasslands (such as in Australia and New Zealand as well as Canada and the USA), selective grazing pressure may have facilitated opportunities for IAPs to establish. We find that grazing stock can be used to manipulate species composition in favour of the desirable components in pastures, but whether grazing is rested or strategically applied depends on the management goal, sizes of populations of the IAP and more desirable species, and climatic and edaphic conditions. Based on our findings, we integrated these relationships to develop a testable framework for managing IAPs with strategic grazing that considers both the current state of the plant community and the desired future state—i.e. the application of the principles behind reclamation, rehabilitation, restoration or all three—over time.

Ammonia-oxidizing archaea and bacteria are structured by geography in biological soil crusts across North American arid lands

Abstract: Introduction Biological soil crusts (BSCs) can dominate surface cover in dry lands worldwide, playing an integral role in arid land biogeochemistry, particularly in N fertilization through fixation and cycling. Nitrification is a characteristic and universal N transformation in BSCs that becomes important for the export of N beyond the microscopic bounds of the crust itself. The contribution of ammonia-oxidizing bacteria (AOB) in BSCs has been shown, but the role and extent of the recently discovered ammonia-oxidizing archaea (AOA) have not.

Continental-scale assessment of provisioning soil functions in Europe

Abstract: A framework is developed to link major soil functions to ecosystem services assessment. Provisioning soil functions—with primary linkages to ecosystem services—are evaluated on a continental scale in Europe. We defined major provisioning soil functions combining the approaches proposed by the Millennium Ecosystem Assessment and the Thematic Strategy for Soil Protection of the European Union. Soil productivity was evaluated by three main land use types (cropland, grassland, forest) using a validated expert model called SoilProd. Models include soil, climate and topographic criteria. Raw material provision capacity of soils was assessed on the basis of (i) organic carbon content and (ii) availability of soil materials for construction. A coherent system of soil function-based ecosystem services was compiled, taking into account major soil functions. We also produced new data on soil-based provisioning ecosystem services, including productivity and raw material availability. The attempts to cover the main human activities requiring materials of soil origin and to map the locations where those materials are available on a continental scale provide new insight to this field of research. Soil-based ecosystem services can be assessed by the evaluation of soil functions which play a role in the production of these services. Quantitative analysis and comparison of the spatial distribution of the investigated soil functions were performed. While crop productivity showed a general trend to increase in a northward and westward direction, local soil quality in most regions—except in the Mediterranean—can compensate for climatic handicaps to a great extent. Comparison of areas with potential for providing ecosystem services by individual soil functions highlights the complexity of decision-making for resource utilization but also the possibilities for optimization and more conscious management.

Cultural and health implications of fish advisories in a Native American community.

Abstract: Introduction: Fish advisories are issued in an effort to protect human health from exposure to contaminants, but Native American communities may suffer unintended health, social, and cultural consequences as a result of warnings against eating local fish. This paper focuses on the Mohawk community of Akwesasne, which lies downstream from a Superfund site, and explores how fish advisories have impacted fish consumption and health. Methods: 65 Akwesasne community members were interviewed between March 2008 and April 2009. Interviews were semi-structured, lasted from 30–90 minutes and consisted of open-ended questions about the impacts of environmental contamination on the community. Detailed field notes were also maintained during extensive visits between 2007–2011. Interviews were transcribed, and these transcripts as well as the field notes were analyzed in NVivo 8.0. This research received approval from the Akwesasne Task Force on the Environment Research Advisory Committee, as well as the Brown University Institutional Review Board. Results: Three-quarters of the 50 Akwesasne Mohawks interviewed have ceased or significantly curtailed their local fish consumption due to the issuance of fish advisories or witnessing or hearing about deformities on fish. Many of these respondents have turned to outside sources of fish, from other communities or from grocery stores. This change in fish consumption concerns many residents because cultural and social connections developed around fishing are being lost and because fish has been replaced with high-fat high-carb processed foods, which has led to other health complications. One-quarter of the 50 interviewees still eat local fish, but these are generally middle-aged or older residents; fish consumption no longer occurs in the multi-generational social context it once did. Conclusions: Human health in Native American communities such as Akwesasne is intimately tied to the health of the environment. Fish advisories should not be used as an institutional control to protect humans from exposure to contaminants; if Akwesasne are to achieve optimal health, the contaminated environment has to be remediated to a level that supports clean, edible fish.

Ammonia-oxidizing archaea and bacteria are structured by geography

Abstract: IntroductionBiological soil crusts (BSCs) can dominate surface cover in dry lands worldwide, playing an integral role in arid land biogeochemistry, particularly in N fertilization through fixation and cycling. Nitrification is a characteristic and universal N transformation in BSCs that becomes important for the export of N beyond the microscopic bounds of the crust itself. The contribution of ammonia-oxidizing bacteria (AOB) in BSCs has been shown, but the role and extent of the recently discovered ammonia-oxidizing archaea (AOA) have not.MethodsWe sampled various types of crusts in four desert regions across the western United States and characterized the composition and size of ammonia-oxidizing communities using clone libraries and quantitative PCR targeting the amoA gene, which codes for the ammonia monooxygenase enzyme, universally present in ammonia-oxidizing microbes.ResultsAll archaeal amoA sequences retrieved from BSCs belonged to the Thaumarchaeota (Nitrososphaera associated Group I.1b). Sequences from the Sonoran Desert, Colorado Plateau, and Great Basin were indistinguishable from each other but distinct from those of the Chihuahuan Desert. Based on amoA gene abundances, archaeal and bacterial ammonia oxidizers were ubiquitous in our survey, but the ratios of archaeal to bacterial ammonia oxidizers shifted from bacterially dominated in northern, cooler deserts to archaeally dominated in southern, warmer deserts.ConclusionsArchaea are shown to be potentially important biogeochemical agents of biological soil crust N cycling. Conditions associated with different types of BSCs and biogeographical factors reveal a niche differentiation between AOA and AOB, possibly driven by temperature.

Nutrient dynamics in the Sundarbans mangrove estuarine system of Bangladesh under different weather and tidal cycles

Abstract: Seasonal and tidal variations in nutrient concentration and water quality were investigated in the western Sundarbans of Bangladesh during the post-monsoon, winter and monsoon seasons during 2010–2011. Water collected from the surface, middle and bottom layers at six locations of the Kholpetua-Arpangashia river system during high and low tides was analyzed for temperature, salinity, pH, dissolved oxygen (DO), total dissolved solids (TDS), electrical conductivity (EC) and dissolved nutrients (NO3–N, PO4–P, SO4 and NH3–N). The study revealed that nutrient concentrations were influenced by seasonal changes. Mean nutrient levels during post-monsoon, winter and monsoon seasons, respectively, were in the following ranges: nitrate (0.06–0.40, 0.06–0.46 and 0.08–0.46 mg/L); phosphate (0.09–0.18, 0.05–0.42 and 0.10–0.16 mg/L); sulphate (58.71–86.14, 68.68–119.01 and 78.15–136.47 mg/L) and ammonia (0.02–0.08, 0.02–0.04 and 0.26–0.38 mg/L). Increased levels of PO4–P, SO4 and NH3–N and lower DO and salinity were recorded during the monsoon period. Most of the experimental sites showed higher NO3–N content during monsoon, whereas few elevated concentrations were observed during post-monsoon and winter periods. High and low tidal waters contained mean nutrient levels in the following ranges: nitrate (0.05–0.46 and 0.04–0.40 mg/L); phosphate (0.05–0.42 and 0.07–0.18 mg/L); sulphate (63.63–125.36 and 58.71–136.47 mg/L) and ammonia (0.02–0.38 and 0.02–0.37 mg/L) without following any distinct fluctuation patterns. The western part of the Sundarbans receives less freshwater input during the monsoon season than other areas of the ecosystem, which reduces the variability of nutrient levels and water quality components. This study provides considerable advances in understanding the seasonality of nutrient distribution with possible tidal influence. The data generated from this study will guide continuing efforts to support a sound management for coastal mangrove ecosystems.

Combining in-situ water quality and remotely sensed data across spatial and temporal scales to measure variability in wet season chlorophyll-a: Great Barrier Reef lagoon (Queensland, Australia)

Abstract: Combining in-situ data from single-point time series with remotely sensed spatial data allowed a greater elucidation of changes in chlorophyll-a concentrations through wet season conditions in the Great Barrier Reef coastal waters. Single-point time-series data were collected from 2006 to 2012 during high river flow conditions to assess changes in phytoplankton biomass (measured as chlorophyll-a). Additionally, three flood plume water types, derived from classified true-colour Aqua moderate resolution imaging spectroradiometer (MODIS) images, were used to group single-point time-series data for the phytoplankton biomass assessment. Survey data illustrate the heterogeneity of chlorophyll-a distribution over seasonal and inter-annual cycles and the difficulty in describing community responses through the wet season. The spatial data demonstrate distinct regional differences throughout the Great Barrier Reef. The high chlorophyll-a concentrations measured in flood plume waters immediately adjacent to the inshore, highly turbid 'inner’ flood plume are a product of sufficient light, given most of the suspended solids have settled from the plume, and the availability of sufficient nutrients, which drive higher phytoplankton production and characterise the formation of secondary stage flood plumes. The formation and extent of these secondary flood plumes were mapped using MODIS true-colour satellite imagery. The distance and the location of the secondary plume water are reliant on flow, coastal hydrodynamics, and biological activity. The combination of in-situ data and remotely sensed data provides information on the complexity of these coastal processes during the wet season and offers managers a more comprehensive understanding of the extent of nutrient enrichment in the Great Barrier Reef coastal area and the potential influence of flood plumes on coastal marine ecosystems.

Is thirty-seven years sufficient for full return of the ant biota following restoration?

Abstract: An assessment of whether rehabilitated mine sites have resulted in natural or novel ecosystems requires monitoring over considerable periods of time or the use of space-for-time substitution (chronosequence) approaches. To provide an assessment of ecosystem recovery in areas mined for bauxite in 1975, the ant fauna of one area planted with Eucalyptus resinifera, one seeded with mixed native species, one topsoiled but unrestored, and a forest reference was subjected to a ‘long-term’ study by sampling monthly and latterly annually between 1976 and 1989 using pitfall traps. These plots were resampled in 2012. A companion ‘short-term’ chronosequence study was performed in 1979 in 28 bauxite mines of various ages and restored by a range of different methods, plus three forest references. In order to examine the assertion that the observed differences between restored areas and forest references will lessen with time, sampling using comparable methods was repeated in 2012 in seven of the original plots, representing progressive advances in rehabilitation technology: planted pines; planted eastern states eucalypts; planted native eucalypts; planted eucalypts over seeded understorey; and planted eucalypts on fresh, double-stripped topsoil, plus two forest reference sites. Ant and other invertebrate richness in the long-term study was initially superior in the seeded plot, with little difference between the planted and unplanted plots. It was concluded that although composition of the ant fauna had converged on that of the forest over the 14-year period, differences still persisted. The 2012 resampling revealed that ant species richness and composition had deteriorated in the seeded plot, while values in the unplanted plot, which now supported naturally colonised trees and an understorey, had increased. Differences between all rehabilitated plots and forest still persisted. As with the long-term study, the rate of fauna return and the type of ants present in the short-term study plots differed with the method of rehabilitation used, and, in 1979, no plots had converged on the forest in terms of the ant assemblage. By 2012 ant richness increased, and more so with each advance in rehabilitation technology, except for seeding, in which the understorey had collapsed. Double-stripping of topsoil resulted in the greatest improvements in ant species richness, although none of the areas had converged on the forest reference areas in terms of assemblage composition or ant functional group profiles. Furthermore, assemblage composition in the forest had changed over time, possibly due to reductions in rainfall, which further complicates rehabilitation objectives. It is concluded that although rehabilitation can achieve its objective of restoring diversity, the original assemblage has still not been achieved after 37 years, suggesting that a degree of novelty has been introduced into these older-style rehabilitated areas. The company’s current rehabilitation practices reflect multiple advances in their approach, lending optimism that current restoration may achieve something close to the original ecosystem, an outcome that can only be verified by extended studies like the one described here.

Cross-scale modeling of surface temperature and tree seedling establishment in mountain landscapes

Abstract: Estimating surface temperature from above-ground field measurements is important for understanding the complex landscape patterns of plant seedling survival and establishment, processes which occur at heights of only several centimeters. Currently, future climate models predict temperature at 2 m above ground, leaving ground-surface microclimate not well characterized. Using a network of field temperature sensors and climate models, a ground-surface temperature method was used to estimate microclimate variability of minimum and maximum temperature. Temperature lapse rates were derived from field temperature sensors and distributed across the landscape capturing differences in solar radiation and cold air drainages modeled at a 30-m spatial resolution. The surface temperature estimation method used for this analysis successfully estimated minimum surface temperatures on north-facing, south-facing, valley, and ridgeline topographic settings, and when compared to measured temperatures yielded an R2 of 0.88, 0.80, 0.88, and 0.80, respectively. Maximum surface temperatures generally had slightly more spatial variability than minimum surface temperatures, resulting in R2 values of 0.86, 0.77, 0.72, and 0.79 for north-facing, south-facing, valley, and ridgeline topographic settings. Quasi-Poisson regressions predicting recruitment of Quercus kelloggii (black oak) seedlings from temperature variables were significantly improved using these estimates of surface temperature compared to air temperature modeled at 2 m. Predicting minimum and maximum ground-surface temperatures using a downscaled climate model coupled with temperature lapse rates estimated from field measurements provides a method for modeling temperature effects on plant recruitment. Such methods could be applied to improve projections of species’ range shifts under climate change. Areas of complex topography can provide intricate microclimates that may allow species to redistribute locally as climate changes.

Regional-scale relationship among biological soil crusts, invasive annual grasses, and disturbance

Abstract: Sagebrush ecosystems in western North America are being replaced by the invasion of annual grasses, particularly Bromus tectorum. In experimental situations and in localized landscapes, prior studies have documented that biological soil crusts (biocrusts) can reduce annual grass presence and that biocrusts are highly vulnerable to physical disturbance. Practical conservation would benefit from verification of these patterns at scales that matter to local economies. This study tests if these patterns appear at a regional scale. A previously collected data set of vegetation provided sampling of biocrust cover across the Great Basin within the state of Nevada, USA. Data were analyzed with non-parametric methods including odds ratios and generalized additive models (GAM). From a data set of 608 vegetation plots within the Great Basin ecoregion, proportion of plots with high annual grass cover differed between sites with high versus low biocrust cover (p = 0.0015). A negative relationship between annual grass cover and biocrust cover was confirmed with GAM (p = 0.009). For a model of biocrust cover, cattle disturbance was found to be an explanatory variable (p < 0.00001). The patterns do appear at the regional scale, with high levels of cattle activity corresponding to low cover of biocrusts, and low cover of biocrusts corresponding to high cover of annual grasses.

Why we gather: traditional gathering in native Northwest California and the future of bio-cultural sovereignty

Abstract: The concept of bio-cultural sovereignty is drawn from Native American Studies scholar Stefano Varese who explores the daily forms of biological and cultural resistance and adaptation in South America. This article extends Varese’s notions by exploring biological and cultural resistance in Native California with a particular focus on the continuing cultural practice of gathering. This article provides a case study analysis of the Lyng v. Northwest Indian Cemetery Protective Association (1988) Supreme Court case and uses traditional ecological knowledge to evaluate how bio-cultural sovereignty is affected by federal land management policies and Western constructions of ecology and the law. The methods are based in an interdisciplinary approach that embraces theoretical notions from linguistics, cultural anthropology, law, environmental justice, history, ecology, and Native American Studies. As a practitioner of traditional ecological knowledge, I offer an analysis of ecological gathering practices to argue that policies, procedures, methodologies, or experiments should be designed in a way that acknowledges the indigenous bio-cultural sovereignty of the land space. Tribes have enacted and continue to enact bio-cultural sovereignty, which solidifies their relationship with the land. Written policies can be used to protect Native interests and to develop a relationship between Native peoples and other agencies. Federal agencies can benefit from these partnerships as tribes can offer assistance to care for these land spaces, state agencies can alleviate potential funding issues for maintaining these areas, and researchers and academics can construct knowledge that incorporates traditional ecological practices to build solid, informed best practices.

Lichen species dominance and the resulting photosynthetic behavior of Sonoran Desert soil crust types (Baja California, Mexico)

Abstract: Lichen dominated biological soil crusts (BSCs) occur over large areas in the Sonoran Desert of the southwestern USA and northwest Mexico. In Baja California BSCs show a distinct patchiness and several types can be distinguished. Two chlorolichen- and two cyanolichen-dominated BSCs were selected. We hypothesize that patchiness and the resulting domination of certain functional lichen groups will result in patchiness of photosynthetic CO2-uptake related to environmental factors as well. Four different soil crust samples were placed in cuvettes and their CO2 exchange was recorded in an open system with an infrared gas analyzer. Air blown over the BSCs had a controlled CO2 content of 350 ppm. Four cuvettes were operated in parallel. Photosynthetic CO2 exchange was continually recorded throughout the experiment. Besides the dominating chlorolichens Psora decipiens and Placidium squamulosum and the cyanolichens Peltula patellata and P. richardsii, several other lichen species and 12 cyanobacterial species were found in the biological soil crusts sampled. The chlorolichen BSCs already gained positive net photosynthesis with high air humidity alone, while the cyanolichen types did not, but showed smaller CO2-uptake depression after water suprasaturation. Such specific net photosynthesis responses to mode of hydration and to crust water content seem to correlate with precipitation characteristics of their habitat. Species specific photosynthetic performance related to activation of respiration and net photosynthesis as well as to crust water content help to explain niche occupation and species composition of BSCs. Different functional types have to be considered when they have a patchy distribution.

Long-term changes in biological soil crust cover and composition

Abstract: Introduction: Communities change over time due to disturbances, variations in climate, and species invasions. Biological soil crust communities are important because they contribute to erosion control and nutrient cycling. Crust types may respond differently to changes in environmental conditions: single-celled organisms and bryophytes quickly recover after a disturbance, while lichens are slow growing and dominate favorable sites. Community change in crusts has seldom been assessed using repeated measures. For this study, we hypothesized that changes in crust composition were related to disturbance, topographic position, and invasive vegetation. Methods: We monitored permanent plots in the Columbia Basin in 1999 and 2010 and compared changes in crust composition, cover, richness, and turnover with predictor variables of herbivore exclosure, elevation, heat load index, time since fire, presence of an invasive grass, and change in cover of the invasive grass. Results: Bryophytes were cosmopolitan with high cover. Dominant lichens did not change dramatically. Indicator taxa differed by monitoring year. Bryophyte and total crust cover declined, and there was lower turnover outside of herbivore exclosures. Lichen cover did not change significantly. Plots that burned recently had high turnover. Increase in taxon richness was correlated with presence of an invasive grass in 1999. Change in cover of the invasive grass was positively related to proportional loss and negatively related to gain. Conclusions: Composition and turnover metrics differed significantly over 11 years, though cover was more stable between years. This study can be a baseline for assessing change in crust composition due to anthropogenic influences.

The effects of indigenous prescribed fire on riparian vegetation in central California

Abstract: Introduction: Fire has a long history, but little documented role, as a process in riparian ecosystems. For millennia California Indians have applied fire to riparian ecosystems for a variety of purposes, but the effects of such fires on riparian vegetation are poorly known outside of traditional knowledge structures of indigenous communities. Methods: This study involved the seasonal application of fire based on traditional ecological knowledge versus alternate burn methods to assess fire effects on riparian vegetation in central California. Results: While the annual variation amongst treatments was not significant, the results of this study suggest that fall burns support higher overall richness and native species richness; spring burns yield a decrease in overall richness, but an increase in native species richness; and summer burns contribute to an initial decline in overall and native species richness. The evenness indices of treatments increase most with spring and summer burning. Conclusion: These findings are key to understanding the seasonal role of fire in managing native species in areas prone to non-native or other invasive species. This research demonstrates the application of traditional ecological knowledge to facilitate an understanding of how prescribed fire could aid in the management and conservation of riparian ecosystems.

Structural development of vegetation on rehabilitated North Stradbroke Island: Above/belowground feedback may facilitate alternative ecological outcomes

Abstract: This study depicts broad-scale revegetation patterns following sand mining on North Stradbroke Island, south-eastern Queensland, Australia. Based on an ecological timeline spanning 4–20 years post-rehabilitation, the structure of these ecosystems (n = 146) was assessed by distinguishing between periods of ‘older’ (pre-1995) and ‘younger’ (post-1995) rehabilitation practices. The general rehabilitation outlook appeared promising, whereby an adequate forest composition and suitable levels of native biodiversity (consisting of mixed-eucalypt communities) were achieved across the majority of rehabilitated sites over a relatively short time. Still, older sites (n = 36) appeared to deviate relative to natural analogues as indicated by their lack of under-storey heath and simplified canopy composition now characterised by mono-dominant black sheoak (Allocasuarina littoralis) reaching up to 60% of the total tree density. These changes coincided with lower soil fertility parameters (e.g., total carbon, total nitrogen, and nutrient holding capacity) leading us to believe that altered growth conditions associated with the initial mining disturbance could have facilitated an opportunistic colonisation by this species. Once established, it is suspected that the black sheoak’s above/belowground ecological behaviour (i.e., relating to its leaf-litter allelopathy and potential for soil-nitrogen fixation) further exacerbated its mono-dominant distribution by inhibiting the development of other native species. Although rehabilitation techniques on-site have undergone refinements to improve site management, our findings support that putative changes in edaphic conditions in combination with the competitive characteristics of some plant species can facilitate conditions leading to alternative ecological outcomes among rehabilitated ecosystems. Based on these outcomes, future studies would benefit from in depth spatio-temporal analyses to verify these mechanisms at finer investigative scales.

Ecological characterization of soil-inhabiting and hypolithic soil crusts within the Knersvlakte, South Africa

Abstract: Within the Knersvlakte, cyanobacteria occur hypolithically underneath translucent quartz stones in areas with quartz pavement and, outside pavement areas, they are soil-inhabiting within the uppermost millimeters of the soil. Both habitats were characterized in terms of biomass and growth patterns of cyanobacteria. Long-term microclimatic conditions were determined. Biomass of organisms within both habitats was determined by means of chlorophyll analyses. A transect approach was used to determine the frequency of hypolithic growth depending on the size, weight, and embedding depth of the quartz pebbles. Organisms were identified by means of microscopic analyses of the samples. Microclimatic conditions within both habitats, i.e., temperature, light intensity, air humidity, and soil moisture, were recorded bi-hourly from September 23, 2004 through September 7, 2006. The biomass of hypolithic and soil-inhabiting crusts was almost identical, 88 vs. 86 mg Chla/m2 and 136 vs. 134 mg Chla+b/m2. Within the quartz fields, 46.8% of the surface area was covered by quartz stones with 69% of translucent quartz stones colonized by hypolithic cyanobacteria and algae. Colonized quartz stones were significantly thicker, heavier, and more deeply embedded in the soil than uncolonized ones. Whereas the annual mean temperature on top of quartz stones was nearly identical to that underneath thin and thick quartz stones, daily temperature amplitudes were largest on the stone surface (up to 48.1K), compared to the hypolithic habitats (up to 39.4K). Light intensity in the hypolithic habitat was between 15 and 30% of the ambient light intensity during daytime. Water condensation in the absence of rain occurred during 50% of the nights on the quartz stone surface, but only during 34% of the nights on the soil surface during winter months within 1 year. Soil moisture beneath quartz layers was greater and less variable than beneath soil-inhabiting crusts. In spite of the large differences in the microclimatic conditions, both habitats seem to be similarly well suited for cyanobacterial growth, resulting in equal biomass values but some differences in taxonomic composition.

Landscape architecture and novel ecosystems: ecological restoration in an expanded field

Abstract: Within the continuum of natural-to-novel ecosystems − i.e., from the ‘pristine’ to the greatly intervened − this paper emphasizes the role of design within highly modified ecosystems in areas of urbanization. It is argued that, as certain landscapes (particularly urbanized ones) can never be restored to original levels of historical ecological fidelity, they should be treated as both cultural and ecological landscapes. It is then proposed that these anthropogenic landscapes would be ready canvases for designed (or planned) novel ecosystems that could be inculcated with ecological function and systems delivery, yet having profound aesthetic manipulation. Based on this landscape architecture perspective, it is suggested that ecologists may not have fully explored cultural interventions in restoring landscapes, especially within the agency of design. A design strategy for the biological hotspot of Perth in southwestern Australia is then provided as a relevant example of how novel ecosystems can be designed. Without an acute and novel approach to modifying current development practices, Perth’s biodiversity is on track for considerable deterioration. From this exploratory backdrop, it is elaborated how neo-baroque design strategies can be used for structuring ecological systems to create resilient and productive novel ecosystems grounded in a critical and autochthonous aesthetic of botanical complexity.

A long term calibration and verification of a submerged aquatic vegetation model for Lake Okeechobee

Abstract: Submerged aquatic vegetation (SAV) has multiple functions in Lake Okeechobee. It provides critical habitat for fish and wildlife, stabilizes sediments, reduces phosphorus (P) concentration in the water column by preventing re-suspension of P-rich sediments, and provides a substrate for attached algae, which also helps to remove P from the water column. Ten year water quality and SAV growth simulations are presented and compared with observed SAV and water quality data collected in the nearshore zone in Lake Okeechobee. The SAV theory and approach used in the LOEM are modified from the Chesapeake Bay model and incorporate three state variables: shoots (above the bed sediment), roots (in the bed sediment), and epiphytes (attached to the shoots). The SAV model has direct linkages with the water quality model, including (1) a link between the growth and decay of SAV and the nutrient pool of the water quality model; (2) a link between the photosynthesis and respiration of SAV and dissolved oxygen dynamics, and (3) the ways in which settling of particulate organic matter and nutrient uptake affect nutrient levels in the water column and in the sediment bed. Total suspended solids affect light attenuation and are another major driving factor for SAV growth in the nearshore and littoral zone area. The model performs reasonably well in reproducing the spatial distribution of SAV. The theoretical analysis and model sensitivity tests indicate that SAV growth is primarily controlled by light and nutrients. The light available for SAV growth depends on the water depth and the turbidity. In this full scale simulation, the water depth comes from the LOEM hydrodynamic model, and the turbidity depends on the suspended sediment concentration and algal concentration.

Biological soil crusts as an integral component of desert environments

Abstract: The biology and ecology of biological soil crusts, a soil surface community of mosses, lichens, cyanobacteria, green algae, fungi, and bacteria, have only recently been a topic of research. Most efforts began in the western U.S. (Cameron, Harper, Rushforth, and St. Clair), Australia (Rogers), and Israel (Friedmann, Evenari, and Lange) in the late 1960s and 1970s (e.g., Friedmann et al. 1967; Evenari 1985, reviewed in Harper and Marble 1988). However, these groups worked independently of each other and, in fact, were often not aware of each other’ sw ork. In addition, biological soil crust communities were seen as more a novelty than a critical component of dryland ecosystems. Since then, researchers have investigated many different aspects of these communities and have shown that although small to microscopic, biological soil crusts are critical in many ecological processes of deserts. They often cover most of desert soil surfaces and substantially

The structure of natural microbial enemy-victim networks

Abstract: The persistence of generalists and specialists is a topical question in community ecology and results from both ecological and evolutionary processes. At fine taxonomical scales, ecological specialisation, i.e. organisms preferentially exploiting a subset of available habitats, is thought to be a driver promoting niche diversity. It is not clear, however, how different mechanisms interact to shape specialist-generalist coexistence. We reconstruct the structure of five bacteria-phage networks from soil isolates, and perform an analysis of the relationships between host phylogenetic diversity, parasite specialism, and parasite performance. We show that the co-occurrence of species on a continuum of specialism/generalism is influenced by niche overlap, phage impact on bacterial hosts, and host phylogenetic structure. In addition, using a null-model analysis we show that infection strategies of the phages have more explanatory power than bacterial defenses on key structural features of these antagonistic communities. We report that generalists have more impact on their hosts than specialists, even when the phylogenetic heterogeneity of hosts is controlled for. We discuss our results in the light of their implications for the evolution of biotic interactions.

Recruitment and functionality traits as bioindicators of ecological restoration success in the Lurg Hills district, Victoria, Australia

Abstract: The Regent Honeyeater Project commenced ecological restoration in the Lurg district in 1994, with an aim to restore habitats for the critically endangered Regent Honeyeater Anthochaera phrygia and a range of other threatened and declining species. Within this context, our study aimed to explore whether plant reproduction can be an effective measure of ecological restoration success. Evaluation involved comparing attributes at unrestored, restored and remnant sites to establish whether sites displayed evidence of a clear restoration trajectory. Five age classes (unrestored, 4–6 years old, 8–10 years old, 12–14 years old and remnant areas) and two landforms (upper hills and lower hills) were considered. The diversity of woody plant species—which have easily recognisable reproductive material and which all recruit seedlings—provides easily measured parameters that have the potential to allow the determination of early establishment success and long-term ecological development of restored ecosystems. Restoration plantings developed in a hybrid state towards a benchmark in the lower hills; seedling species composition differed significantly among age classes, increasing in similarity with time since restoration, with some divergence from the target pathway. Composition of functional groups with reproductive outputs was also significantly different among age classes; however, a restoration trajectory was only evident in the upper hills where sites converged towards the target goal. Divergence or deviation from the restoration trajectory was not deemed to be a restoration failure, as the variety of functional groups with fruits and diversity of seedlings recruiting indicated a potential increase in resilience in the future due to greater variability across the landscape. Plant recruitment was effective in detecting development trends towards a restoration target in this study and therefore may be a useful measure that contributes to determining ecological restoration success.