Samples were collected at 0, 3, and 6 h following illumination with red light. The remainder of the culture was then placed under an IR LED for an additional 12 h, after which a final sample was collected. Upon collection, cells were immediately treated with 475 μL 100% ethanol and fixed for 1 h at room temperature. Cells were then pelleted, washed once with 50 mM sodium citrate , and then resuspended in 500 μL 50 mM sodium citrate to which RNaseA had been added. Following an incubation for 1 h at 37˚C, 50 μL proteinase K was added to a final concentration of 2 mg/mL and cells were incubated at 50˚C for an additional hour. SYTOX green was then added to each sample to a final concentration of 2 μM, and cells were incubated for 1 h at room temperature. Inparallel, control samples were prepared containing exponentially growing cultures of yeast treated with α-factor for for ~3 h prior to fixation and staining. Ploidy was determined by measuring the fluorescence intensity of SYTOX green staining by flow cytometry using a FACSAria III and normalizing to the α-factor-treated samples, which have a ploidy of 1N. For each time point for each independent experiment, 50,000 cells were measured. Analysis of flow cytometry data was performed using FlowJo and Flowing Software .Intact natural landscapes provide ecosystem functions that result in numerous ecosystem goods and services from which humans benefit, including carbon storage, flood protection, and maintenance of species life cycles . However, many of these services are diminished in landscapes that have been converted for agricultural purposes. The provisioning services of these food-production landscapes are clear, and there is increasing recognition that agricultural landscapes can continue to supply or maintain other vital ecosystem services if well managed. These include flood mitigation and carbon storage , pollination ,mobile grow rack and wildlife habitat . Maintaining ecosystem functions to optimize these multiple services in agricultural landscapes is particularly important, given that cropland and pasture currently occupy ~40% of the earth’s land surface, with increases predicted to support a growing global population .
In the past, agricultural production was characterized by growing one or more crops in the same place. Crop rotation would provide inputs of nitrogen, and suppress insects and weeds by breaking their life cycles, yielding modest but stable agricultural inputs . However, this link between ecology and agriculture has become strained over the past few decades a a result of mechanization, new crop varieties, development of agrochemicals, as well as political and economic forces associated with regional agriculture’s supplying international markets . This has led to concerns about the long-term sustainability of food-production systems, and the influence of these practices on the ecosystem services provided to people. An increasing number of studies show how creating diverse agricultural landscapes, through patches of remnant or revegetated native habitat on farmland, even on a small scale, can provide important habitat for native flora and fauna, as well as benefit farm productivity in unexpected ways . For example, fields with uncultivated margins have higher plant and moth diversity as well as more diverse soil macrofauna . Hedgerows have been associated with higher bird and moth diversity, provide movement corridors for fauna and host natural enemies that control agricultural pests . In addition, remnant areas close to agricultural areas improve pollination services with positive consequences for crop yields . Furthermore, agricultural lands store carbon through remnant native vegetation and from the crops cultivated, particularly annual row crops because of their dense planting . Similarly below-ground biomass could be increased by introducing cover crops with deeper roots to increase below-ground biomass while food is still produced . Other ecosystem services from certain types of agriculture include aesthetic landscapes , farm tourism , and the preservation of rural lifestyles . Agriculture can also be the source of ecosystem disservices such as habitat loss and pesticide poisoning of non-targeted species , while soil and nutrient runoff result in losses of soil carbon . The effect of these disservices ranges from the local scale to the regional scale , to the global scale . For example, 20% of the N fertilizer applied in agricultural systems globally moves to aquatic ecosystems . Agricultural production practices in California, which produces roughly half of the fruits, nuts, and vegetables for the U.S, has resulted in widespread nitrate contamination of groundwater aquifers . An emerging body of literature focuses on spatially quantifying ecosystem services and comparing these with patterns of biodiversity across the landscape and agricultural land returns . For example, Nelson et al.
Assessed these three components under alternative land-use trajectories in the Willamette Basin, Oregon. The study found that a conservation scenario which resulted in high scores for ecosystem services also had high scores for biodiversity, while a development scenario had higher returns to land-owners but lower levels of biodiversity conservation and ecosystem services. Polasky et al. in an assessment of land-use alternatives over a 10-year period in Minnesota found a lack of concordance—the scenarios that created the greatest annual net returns to land-owners also had the lowest social benefits. Agricultural expansion was found to reduce stored carbon, negatively affect water quality, and reduce habitat quality for biodiversity and forest songbirds. The present study has elements similar to Nelson et al. and Polasky et al. . It is conducted at the parcel spatial scale, it is forward looking to 2050, and it addresses ecosystem services and disservices along with biodiversity and financial returns from agriculture. In this study, we examine the assumption that land use change in agriculturally dominated areas provides positive benefits for land-owners and financial agricultural returns at the expense of biodiversity and other ecosystem services, such as carbon storage. We do this by quantifying carbon storage, landscape suitability for birds, ecosystem disservices, and financial returns from agriculture within an area of the Central Valley of California. We ask how these change by 2050 under three alternative scenarios: restoration, urbanization, and enhanced agriculture tailored to the needs of a key species of conservation concern, the Swainson’s Hawk. The study area spans a 72,188-ha area in the Central Valley that includes the Cosumnes River Preserve and surrounding lands up to 50m in elevation, encompassing lands owned privately, by state and federal government, or by non-profit organizations including The Nature Conservancy . Historically, this area was dominated by native grassland, valley oak woodland and savanna, and riparian forest along the once-perennial Cosumnes River. However, conversion to agriculture has resulted in a landscape where only small patches of natural habitat remain. Many of these remnant natural areas are currently experiencing conversion to urban land use from the rapidly growing adjacent cities. Although some of these natural areas are habitat for state- and federally-listed threatened and endangered species and, consequently, development of these lands has resulted in mitigation funding to compensate for habitat losses of imperiled species. Currently, natural vegetation covers 44% of the study area,ebb and flow table based on a vegetation map of the Delta developed by the California Department of Fish and Wildlife in addition to project-based vegetation mapping.
The urban and developed footprint, which currently covers 9% of the study area, has increased by 35% over the last decade . Urban expansion associated with cities at the northern and southern edges of the study area continues to exert development pressure on remaining natural and agricultural lands. Today, the river channel is lined with agricultural levees, and adjacent floodplains are used largely for crops , with agriculture covering 46% of the study area. Agricultural activity in the study area, compared to large-scale agriculture in many other parts of California, has a high diversity of crops across many small parcels. Our agricultural land-use scenario represents an enhanced agriculture which favors compatible crops that are commonly the targets for mitigating habitat loss for the imperiled Swainson’s Hawk through mitigation funding. This scenario is reasonable, given that the region is highly suitable for Swainson’s Hawk nesting and foraging, supporting one of the highest concentrations of birds in the Pacific Flyway. Because B. swainsoni is a species of concern, priority has been placed on managing the landscape for its persistence. Both governmental and nongovernmental land managers currently engage in a number of practices intended to boost populations of avian species of concern, for example, paying farmers to flood fallow fields to provide habitat for migrating waterfowl. Given their conservation priority status, it is possible that management agencies might also pay farmers to enhance habitat for improved outcomes for the Swainson’s Hawk. The widespread use of conservation easements within the study area provides the mechanism and the means to accomplish an enhanced agricultural scenario. The Yolo County Habitat Conservation Plan/Natural Community Conservation Plan is one such policy that points toward management for this species. The Swainson’s Hawk can also be a valuable focal species because of its dependence on tree canopy nesting sites and nearby open-country foraging habitat. Many other raptors, riparian species, and migratory birds also depend on these ecosystem traits. The Swainson’s Hawk is able to forage in specific types of agriculture . In particular, alfalfa is a valuable resource because it is a perennial crop that continually supports high populations of prey whose availability peaks during monthly irrigation and harvesting events. Other crops, such as beet and tomato fields, are also hunted regularly during harvest, though crops such as rice or vineyards are not significantly utilized . The same crop associations are true for a number of other species. Alfalfa, in particular, is considered important habitat for other migratory birds, including shorebirds like Long-Billed Curlew and White-Faced Ibis , both of which are species of conservation concern. The Swainson’s Hawk responds well to protection and restoration of riparian forest habitats , within an agricultural landscape that is used for foraging . Thus, a varying matrix of natural riparian habitat and different forms of agriculture can reasonably be expected to significantly affect the value of the landscape for this species.
The potential for multi-species benefits from single species mitigation or management is rarely evaluated; therefore, we include an assessment of the ramifications of these land-use scenarios for 15 other focal bird species identified by the California Partners in Flight program . These are a suite of species whose requirements define different spatial attributes, habitat characteristics, and management regimes, and represent healthy habitats within our focal landscape . We conducted this study at the parcel scale , which is meaningful because land management decisions for agricultural practices are made at this scale and only a few ecosystem services quantification studies have been conducted at this scale . The average size of parcels in the study area that grow alfalfa, grain, orchard, rice, row crop, or vineyard was 3.88ha . To assess the changes over time among carbon storage, landscape suitability for birds, ecosystem disservices, and returns from agriculture with each of our management scenarios, we first developed a snapshot of the current land cover in the study area. We mapped urban areas using information from the Sacramento Area Council of Governments data from 2005, with a minimum mapping unit of five acres for urban areas and ten acres for rural areas. We defined agricultural land cover data from the CDFW’s Delta vegetation map and from the California Department of Water Resources , with a minimum mapping unit of 10 acres .These were considered sufficiently distinct from each other in terms of foraging value for Swainson’s Hawk. In addition to these agricultural classes, we used four natural vegetation classes along with developed/ urban and water . These land-cover types were intersected with land-owner parcels for the study area . In cases where a parcel contained more than one land use type, the parcel was split into the respective classes to retain this detail. These resultant land- cover data represent the contemporary baseline condition from which we measured changes resulting from the landscape management scenarios. We conducted spatial analysis in ESRI ArcMap version 10.3, in Universal Transverse Mercator projection with North American Datum 1983.We consulted with management stakeholders at the Cosumnes River Preserve to develop three management scenarios to simulate potential changes in the current landscape: extensive restoration, urbanization, and enhanced agriculture designed to benefit the Swainson’s Hawk.