Regional Conservation Objectives Research Articles

Slow and Steady: Gradual Drawdown of Private Wetlands Supports Shorebirds During Northbound Migration

AbstractThe Grasslands Ecological Area is the largest contiguous wetland complex in California's Central Valley and is a stronghold for hundreds of thousands of waterbirds. Primarily managed for waterfowl habitat and forage production, landowners of these privately owned seasonal wetlands in the Grassland Ecological Area typically flood the wetlands in the fall and dewater them the following spring in February and March. These wetlands support large populations of nonbreeding shorebirds and other waterbirds in winter. When the number of migratory shorebirds using the region peaks in mid-April, landowners have already dewatered most wetlands. The mismatch in the timing of available habitat and the habitat needs of migrating shorebirds contributes to the observed deficit of shorebird habitat in the Central Valley in spring. Working with private landowners, we developed and tested a wetland management practice designed to increase the amount of shallow-water habitat available to shorebirds in April by delaying the drawdown and reducing water levels more slowly (gradual drawdown) relative to the traditional management practice. On average, we found that wetlands managed with gradual drawdown provided over twice as much shorebird habitat, contributing up to 26% of the overall shorebird habitat objective for the Central Valley. Wetlands managed with gradual drawdown supported up to 21 times more migratory shorebirds during peak migration and a greater number of shorebird species than traditionally managed wetlands. Our results demonstrate the potential of working with private landowners to implement small changes in wetland management that can have a large impact in meeting regional conservation objectives for migratory shorebirds.

Response Characteristics of Chinese Pine (Pinus tabulaeformis Carr.) Radial Growth to Climate and Drought Variability Reconstruction in Western Liaoning, Northeast China

Chinese pine (Pinus tabulaeformis Carr.) plays an important role in maintaining ecosystem health and stability in western Liaoning Province and the southern Horqin sand land, Northeast China, with benefits including sand fixation and soil erosion. In the context of climate change, developing a better understanding of the relationship between climate factors and growth rates of this species will be extremely valuable in guiding management activities and meeting regional conservation objectives. Here, the results based on two groups of tree-ring samples show that the radial growth of Chinese pine is controlled primarily by water conditions. The longer chronology had the highest correlation coefficient with the January–September mean self-calibrating Palmer Drought Severity Index (scPDSI); therefore, drought variability was reconstructed for the period 1859–2014. Statistical analysis showed that our model explained 41.9% of the variance in radial growth during the 1951–2014 calibration period. Extreme dry and wet events, defined as the criteria of one standard deviation less or greater than the mean value, accounted for 19.9% and 18.6% of the 156-year climate record, respectively. During the past century, the regional hydroclimate experienced significant long-term fluctuations. The dry periods occurred from the early-1900s–1930s and 1980s–2000s, and the wet periods occurred from the 1940s–1970s. The drought reconstruction was consistent with the decreasing trend of the East Asian summer monsoon since the late 1970s. The reconstructed temporal patterns in hydroclimate in western Liaoning were closely related to the large-scale climate drivers in the North Pacific and the tropical equatorial Pacific. The teleconnections were confirmed by spatial correlations between the reconstructed sequence and sea surface temperature (SST) in the North Pacific, as well as the correlations with the Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO) indices. Aerosols played an important role in affecting drought variations over the past several decades. Moisture stress caused by global warming and interdecadal changes in the PDO will have long-term effects on the growth of pines in the study area in the future.

Estimating Waterfowl Carrying Capacity at Local Scales: A Case Study From Edwin B. Forsythe National Wildlife Refuge, New Jersey1

Abstract The management of wintering North American waterfowl is based on the premise that the amount of foraging habitat can limit populations. To estimate carrying capacity of winter habitats, managers use bioenergetic models to quantify energy (food) availability and energy demand, and use results as planning tools to meet regional conservation objectives. Regional models provide only coarse estimates of carrying capacity because habitat area, habitat energy values, and temporal trends in population-level demand are difficult to quantify precisely at large scales. We took advantage of detailed data previously collected on wintering waterfowl at Edwin B. Forsythe National Wildlife Refuge and surrounding marsh, New Jersey, and created a well-constrained local model of carrying capacity. We used 1,223 core samples collected between 2006 and 2015 to estimate food availability. We used species-specific 24-h time–activity data collected between 2011 and 2013 to estimate daily energy expenditure, morphometrically corrected for site- and day-specific thermoregulatory costs. To estimate population-level energy demand, we used standardized monthly ground surveys (2005–2014) to create a migration curve, and proportionally scaled that to fit aerial survey data (2005–2014). Crucially, we also explicitly incorporated estimates of variance in all of these parameters and conducted a sensitivity analysis to diagnose the most important sources of variation in the model. Our results from an outlier-removed, a strict depletion model indicated that at estimated mean levels of supply (923 million kcal) and cumulative demand (3.4 billion kcal), refuge food resources were depleted before November. However, a constant-supply model that represented tidal replenishment of resources indicated that just enough energy was present to sustain peak winter populations. Variation in model output appeared to be driven primarily by uncertainty in population abundance during peak periods of use, emphasizing a new management focus on studying migration chronologies of waterfowl. This model allows for relative assessment of biases and uncertainties in carrying-capacity modeling, and serves as a framework identifying critical science needs to improve local and regional waterfowl management planning.

Notice: The authors have discovered an error in raw data analyzed in this paper. This article has been retracted. The corrected article is published online early as Ringelman KM, Williams CK, Castelli PM, Sieges ML, Longenecker RA, Nichols TC, Earsom AD. 2018. Estimating waterfowl carrying capacity at local scales: A case study from Edwin B. Forsythe National Wildlife Refuge, New

Abstract The management of wintering North American waterfowl is based on the premise that the amount of foraging habitat can limit populations. To estimate carrying capacity of winter habitats, managers use bioenergetic models to quantify energy (food) availability and energy demand, and use results as planning tools to meet regional conservation objectives. Regional models provide only coarse estimates of carrying capacity because habitat area, habitat energy values, and temporal trends in population-level demand are difficult to quantify precisely at large scales. We took advantage of detailed data previously collected on wintering waterfowl at Edwin B. Forsythe National Wildlife Refuge and surrounding marsh, New Jersey, USA, and created a well-constrained local model of carrying capacity. We used 1,223 core samples collected between 2006 and 2015 to estimate available food. We used species-specific 24-h time-activity data collected between 2011 and 2013 to estimate daily energy expenditure, morphometrically corrected for site- and day-specific thermoregulatory costs. To estimate population-level energy demand, we used standardized monthly ground-surveys (2005–2014) to create a migration curve, and proportionally scaled that to fit aerial survey data (2005–2014). Crucially, we also explicitly incorporated estimates of variance in all of these parameters and conducted a sensitivity analysis to diagnose the most important sources of variation in the model. Our results indicated that at estimated mean levels of supply (2.34 × 109 kcal) and cumulative demand (3.4 × 109 kcal), refuge resources were depleted before the end of the wintering season. However, at one standard error greater in supply and one standard error less in demand, 1.33 × 109 kcal remained on the landscape at the end of winter. Variation in model output appeared to be driven primarily by uncertainty in food abundance in high marsh habitats. This model allows for relative assessment of biases and uncertainties in carrying capacity modeling, and serves as a framework identifying critical science needs to improve local and regional waterfowl management planning.

Reciprocal feedbacks between spatial subsidies and reserve networks in coral reef meta-ecosystems.

Top-down processes such as predation and herbivory have been shown to control the dynamics of communities across a range of ecosystems by generating trophic cascades. However, theory is only beginning to describe how these local trophic processes interact with spatial subsidies in the form of material (nutrient, detritus) transport and organismal dispersal to (1) shape the structure of interconnected (meta-) ecosystems and (2) determine their optimal management via reserve networks. Here, we develop a meta-ecosystem model to understand how the reciprocal feedbacks between spatial subsidies and reserve networks modulate the importance of top-down control in a simple herbivorous fish-macroalgae-coral system. We show that in large and isolated reserve networks where connectivity between protected and unprotected areas is limited, spatial subsidies remain largely confined to reserves. This retention of spatial subsidies promotes the top-down control of corals and macroalgae by herbivores inside reserves but reduces it outside reserves. Conversely, in small and aggregated reserves where connectivity between protected and unprotected areas is high, the spillover of spatial subsidies causes a reduction in top-down control of corals and macroalgae by herbivores inside reserves and an increase in the strength of top-down control outside reserves. In addition, we demonstrate that there is a trade-off between local and regional conservation objectives when designing reserve networks: small and aggregated reserves based on the extent of dispersal maximize the abundance of corals and herbivores regionally, whereas large and isolated reserves always maximize the abundance of corals within reserves, regardless of the extent of dispersal. The existence of such "conservation traps," which arise from the fulfillment of population-level objectives within local reserves at the cost of community-level objectives at regional scales, suggests the importance of adopting a more holistic strategy to manage complex and interconnected ecosystems.

Maximizing the ecological contribution of conservation banks

ABSTRACTIn 1995, California established the first conservation banking program in the United States to provide a new financial mechanism to conserve wildlife and natural communities in rapidly developing regions. Conservation banks are lands protected and managed for conservation of species of concern. Developers may purchase species credits from a conservation bank to offset adverse impacts of development at another site. Conservation banks facilitate pooling of mitigation resources from multiple development projects to protect planned habitat reserves of greater ecological value than can be achieved with project‐by‐project mitigation. In this study, we conducted the first ever assessment of the ecological performance of the California Conservation Banking Program. Specifically, we investigated to what extent conservation banks contribute to achieving regional conservation objectives. We hypothesized that conservation banks within a region should have similarly high ecological values if they are appropriately evaluated and prioritized based on principles of conservation planning. We created a new ecological value metric to evaluate and rank conservation banks and used it to compare potential conservation banks or reserves within a region. We found the ecological value of banks within regions varied and concluded that maximizing the ecological contribution of conservation banks requires prioritization of lands for potential bank sites and reserves. Our analysis identified circumstances where conservation banking is not an appropriate mitigation mechanism to protect rare species and natural communities. We concluded that limited funding for conservation planning should be directed toward regions where species of concern are wide‐ranging, biodiversity is highly variable, threats to species of concern are highly varied, and there are many potential conservation bank sites. © 2014 The Wildlife Society.

Bridging the gap between the Natura 2000 regional conservation status and local conservation objectives

Natura 2000 targets the sustainable conservation of Europe's biodiversity. An important cornerstone of Natura 2000 is the Habitats Directive, which is currently implemented across European member states. However, straightforward implementation is not obvious since the favourable conservation status of habitats and species needs to be achieved at the member state level, while conservation objectives need to be formulated at the protected site level. To bridge this gap, we propose to start from regional conservation objectives before site level objectives are formulated. These regional conservation objectives have the advantage of providing a framework according to which conservation objectives can be allocated both within and outside the protected sites of the Natura 2000 network. Especially since they all contribute to the national or regional conservation status. Recently, Flanders (northern Belgium) has adopted this approach and has quantified conservation objectives at the regional scale. As the current regional conservation status of habitats and species is mostly unfavourable, regional conservation objectives entail a drastic increase in area (42%) for habitats, and active conservation measures for 78% of the species. We are convinced that the method outlined here, may substantially contribute to a helpful discussion about implementing and streamlining Natura 2000 across European member states.

Integration of Regional Mitigation Assessment and Conservation Planning

Thorne, J. H., P. R. Huber, E. H. Girvetz, J. Quinn, and M. C. McCoy. 2009. Integration of regional mitigation assessment and conservation planning. Ecology and Society 14(1): 47. https://doi.org/10.5751/ES-02949-140147

Assessing sustainability indicators for tropical forests: Spatio-temporal heterogeneity, logging intensity, and dung beetle communities

Sustainable management of tropical forests has been identified as one of the main objectives for conservation of global biodiversity and management of carbon stocks. To achieve this goal, managers need tools to assess the sustainability of current management practices. Several international initiatives have undertaken the development of sets of criteria and indicators to help managers move towards sustainability. Among the indicators considered, the structure and composition of dung beetle communities have been identified as excellent indicators of ecological sustainability. However, as occurs with most indicators of the ecological sustainability of forest management, dung beetle surveys require intensive field work making their application over large areas expensive, time consuming, and logistically challenging. A need for prioritization is evident. This work presents a novel approach to the assessment of the Center for International Forestry Research (CIFOR) ecological sustainability indicator I.2.1.2: “The change in diversity of habitats as a result of human interventions is maintained within critical limits as defined by natural variation and/or regional conservation objectives”. Using variography of vegetation index data derived from remotely sensed imagery, we show (1) how the differences in forest structural heterogeneity observed between forest management units and natural areas can be used to identify priority areas for field survey of ecological sustainability indicators (hereafter “priority-for-survey”) and (2) how these priorities correspond to dung beetle community structure and composition. Links between temporal change in forest structural heterogeneity, logging intensity, and dung beetle community structure and composition were established by means of correlation analysis and matrix regression modeling. We found that areas ranked as low priority-for-survey based on image analysis showed no significant difference in dung beetle species richness or diversity from natural reference areas. Further, we found significantly higher dung beetle species richness and diversity estimates in areas ranked as moderate or moderate-low priority-for-survey over the low and reference areas. Finally, the dung beetle community composition in the high priority-for-survey category was significantly less rich and less diverse than any other category. We identified a logging intensity threshold of four trees per hectare as a transition to significant differences in forest structural heterogeneity and the richness and diversity of associated dung beetle communities.

Reproduction and Captive Breeding as a Tool for Mammal Conservation: The Role of Modem Zoos.

There is a growing awareness in the scientific research community of the role that zoological institutions can play in the conservation of threatened or endangered species. Zoos themselves have changed and become more focussed on the contributions they can make to regional conservation objectives, driven in part by the "World Zoo Conservation Strategy" published in 1993. Perth Zoo has committed itself to this strategy and established a collaborative scientific research program with Conservation and Land Management (CALM), WA, to develop captive breeding techniques for a number of Western Australian native species. To achieve this objective, the zoo has established a sub-program known as the Native Species Breeding Program. This consists of 6 specialist keepers who are charged with developing specialised skills in captive husbandry of selected species, and the implementation of research projects. All of the species under study are part of recovery plans, and many of the species are being produced for release under the objectives of those plans and as part of CALM's "Western Shield Project". Mammal species under study are the Numbat, Chuditch, Dibbler, Djoongari (Shark Bay Mouse) and the Wopilkara (Greater Stick Nest Rat). Currently, Chuditch, Numbats and Djoongari bred in captivity have been the subject of re-introduction programs. The results of these breeding programs and the subsequent releases of selected species into different habitats in Western Australia will be presented, along with a discussion of the issues which relate to the limitations of captive breeding as a conservation tool.