Symposium Abstracts 2013

2013 Symposium Poster Presentation Abstracts

John Haggerty
ECOLOGICAL SCALE OF MICROBIAL BIODIVERSITY
Graduate Group in Ecology                                       
In marine systems, microbial communities act as nutrient cyclers, pathogens, indicators of settlement, sources of toxins and symbionts. Metagenomics has allowed rapid advancements in microbial studies of archaeal and bacterial communities through mass sequencing of random fragments of environmental DNA and assignment of closest similarities to known taxonomic and functional genes. Because microbes function at the micrometer level, the appropriate ecological scale to measure microbial diversity is debated. To determine variability of marine water column microbes, samples from a meter bellow the waters surface are compared to paired samples of southern kelp forest systems and across a global survey. Global analysis shows distinct oceanographic differentiation of community diversity and function. Southern California kelp forests show a distinct taxonomic diversity with higher proportions of Proteobacteria and Firmicutes in La Jolla than neighboring Pacific Beach and Point Loma kelp forests. Functional diversity is more consistent in kelp forest systems when compared to marine communities across the globe. Significant differences in genes encoding virulence and metabolism of sulfur, potassium and aromatic carbons were found between kelp forests and samples from Galapagos, coral atolls and the Indian Ocean. Findings indicate that diversity of marine surface waters becomes increasingly homogeneous with smaller sampling areas.

Mila Hickenbottom
FUELS AND FOREST STRUCTURE IN THE SIERRA SAN
PEDRO MARTIR
Graduate Group in Ecology     
The relationship between agricultural management, and resistance and resilience of microbial communities in agricultural soils when exposed to a severe environmental perturbation is key to long-term agricultural sustainability. Agricultural management practices generally have large impacts on soil through physical disturbance, inputs of fertilizers and pesticides, and cultivation of monoculture or low-diversity plant systems. Resistance of soil microbial communities to disturbance events is a topic of growing importance with predicted rising temperatures and large unpredictability in rainfall patterns associated with global climate change. Diverse microbial communities are essential for the sustainability of agriculture. Previous research has focused on the resistance of soil systems in relation to total microbial biomass but has ignored relationships with specific functional groups of microbes. Nitrifiers and denitrifiers are key organisms in N cycling and these organisms control the pools of plant-available N in soil, while alkaline phosphatase is a key microbially produced enzyme involved in the regulation of pools of available phosphate. In this study, numbers of nitrifying and denitrifying genes as well as gene involved in alkaline phosphatase production were quantified after subjecting different managed agricultural soils to severe temperature perturbation.

Marshall McMunn                                                
THE DARK SIDE OF PLANT DEFENSE: COMPARING NOCTURNAL AND DIURNAL DEFENSIVE INDUCTION IN BIG SAGEBRUSH
Population Biology Graduate Group
Background/Question/Methods – Inducible defensive traits allow plants to efficiently manage their limited resources and respond to current herbivore pressure. My primary research question was: big sagebrush (Artemisia tridentata)  induce defensive traits with equal effectiveness at different times of day? In order to answer this question I systematically damaged 200 sagebrush plants within Tahoe National Forest at different times of day and night. The distal third of 100 leaves were removed from an emitter branch on each plant during the designated time periods. This simulated an intense but realistic pulse of herbivore activity during the experimental time window. I then counted undamaged and damaged leaves on a neighbor branch in October 2012 as an assessment of season-long palatability to herbivores.  
Results/Conclusions – Plants receiving simulated herbivory during the night had a higher proportion of damaged leaves than plants that received simulated herbivory during the day. Diurnal simulated herbivory was more effective in inducing defenses, and these plants received a lower proportion of damaged leaves over the course of the season. These results demonstrate that when testing plant defensive responses, scientists should not only consider the identity of the herbivore but also the timing of the herbivore attack. The relationship between agricultural management, and resistance and resilience of microbial communities in agricultural soils when exposed to a severe environmental perturbation is key to long-term agricultural sustainability. Agricultural management practices generally have large impacts on soil through physical disturbance, inputs of fertilizers and pesticides, and cultivation of monoculture or low-diversity plant systems. Resistance of soil microbial communities to disturbance events is a topic of growing importance with predicted rising temperatures and large unpredictability in rainfall patterns associated with global climate change. Diverse microbial communities are essential for the sustainability of agriculture. Previous research has focused on the resistance of soil systems in relation to total microbial biomass but has ignored relationships with specific functional groups of microbes. Nitrifiers and denitrifiers are key organisms in N cycling and these organisms control the pools of plant-available N in soil, while alkaline phosphatase is a key microbially produced enzyme involved in the regulation of pools of available phosphate. In this study, numbers of nitrifying and denitrifying genes as well as gene involved in alkaline phosphatase production were quantified after subjecting different managed agricultural soils to severe temperature perturbation.

Karin Nguyen 
ASSESSMENT OF FIELD METHODS FOR QUANTIFYING NATIVE POLLINATORS IN RESTORED AGRICULTURAL HEDGEROWS
Land, Air, and Water Resources
A variety of conservation initiatives have supported restoration of the margins of farmland in Yolo County, CA, through the planting of native shrubs, herbaceous flowering plants and grasses. One of the major goals of these restored hedgerows is to provide habitat for native pollinators, including bees and syrphid flies in intensely managed agricultural landscapes. This study compares the abundance and diversity of bees at five hedgerows soon after they were established (2008) and three years later (2011), with the abundance and diversity of insects found on three fully mature hedgerows. The goal of this project is to look at the success of the restoration so far to see if we are able to detect increases in the development in the insect community, and whether these increases may be correlated with particular features of the restoration site. We placed twenty-one open pan traps along the selected 50meters hedgerows and netted insects which landed on reproductive flower parts for six ten minute intervals. Analysis of preliminary data compared two indirect indices of bee population: abundance and diversity. Preliminary results indicate that current sampling techniques may not accurately represent the actual abundance and diversity of insects at these sites.

Erin Wilkus 
RELATING FARMERS’ PERCEPTION OF SEED DIVERSITY AND SEED STOCK MANAGEMENT ON BEAN DIVERSITY IN UGANDAN AND TANZANIA FARMER FIELDS
Graduate Group in Ecology 
TBA

Boon-Ling Yeo   
TAXES OR TRADABLE PERMITS: UNDERSTANDING ENVIRONMENTAL POLICIES FOR ABATEMENT OPTIONS THAT AFFECT MULTIPLE TYPES OF POLLUTION
Graduate Group in Ecology
The intensity of agricultural production affects both nutrient and greenhouse gas (GHG) emissions. Environmental policy designed to reduce one type of pollution may help mitigate or in some cases increase the pollution level of another.  This paper develops a theoretical agro-environmental economic model that analyzes how the interactions of multiple farm management options and land-use choices affect the level of two different but related types of pollution.  It explores the effect of pollution taxes vs. tradable permits when there are multiple abatement options affecting several types of pollution; and it examines how environmental impacts depend on the extent to which farm management options are complements or substitutes.  This research suggests that when the two farm management options are complements; pollution levels unambiguously decrease as pollution charges increases. When farm management options are substitutes, an increase in the tax on GHG emissions can inadvertently increase nutrient runoffs.

2013 Symposium Oral Presentation Abstracts

Rachel Anderson  
IMPACT OF THE INTRODUCED AMERICAN BULLFROG, LITHOBATES CATESBEIANUS, ON INVADED COMMUNITIES
Graduate Group in Ecology
Invasive species like the American Bullfrog (Lithobates catesbeianus) represent a serious threat to biodiversity worldwide, especially when they impact invaded communities on multiple levels due to complex life histories.  Evidence is accumulating that Bullfrogs are at least partly responsible for the decline of native amphibian populations in western North America and elsewhere: the appearance of bullfrogs at breeding ponds tends to correspond with the disappearance of other ranids.  The larval, juvenile, and adult stages each present unique threats to native amphibian species, and all life stages thrive in human-modified, degraded, and invaded habitats, exacerbating their negative impacts.  Future research into the management of invaded communities should take into account the impact of different bullfrog life stages on the specific system of concern.

Joy Cookingham
RATES OF LEAF LITTER NITROGEN FIXATION DIFFER BETWEEN TWO TROPICAL RAINFOREST GROWING ON CONTRASTING LITHOLOGY
Graduate Group in Ecology
Biological nitrogen fixation (BNF) — the conversion of atmospheric di-nitrogen (N2) into bioavailable ammonium — is the principal non-anthropogenic input of N into ecosystems.  N limits plant productivity and carbon exchange at the global scale, yet our understanding of this process’ rates and controls are limited, especially for litter N fixation in tropical ecosystems. My study site is in southern Belize, where there are two neighboring rainforests with different lithology (volcanic and limestone), which corresponds to different ecosystem-wide concentrations in total phosphorus. My study asks: how do rates of N fixation in neighboring tropical rainforests relate to lithology and phosphorus concentrations? To address this question, I measured rates of litter N fixation and total nitrogen and phosphorus pools in soil and litter in the two forests.  I found the limestone sites to have higher total soil phosphorus than the volcanic site, which corresponds with higher rates of litter N fixation in the limestone site. The positive correlation between N fixation and total soil phosphorus is likely due to the fact N fixation is an energy intensive process requiring significant amounts of P as ATP.  However, further research is needed to fully understand the biogeochemical constraints on litter nitrogen fixation in lowland tropical forests.

Raymond Crafton
MODELING INVASION RISK: COMBINING ENVIRONMENTAL SUITABILITY AND INTRODUCTION LIKELIHOOD
Graduate Group in Ecology 
Invasive species are of key concern to researchers, managers, and policy makers and can be ecologically and economically costly. Assessing invasion risk requires understanding both where a species can exist and the likelihood of that species arriving. Furthermore, future changes to global climatic and socioeconomic landscapes could modify where species are likely to invade. This research aims to develop a model to assess invasion risk for marine and estuarine species that combines species habitat modeling and the likelihood of introduction using New Zealand as a case study. This model combines the use of Maxent for species habitat modeling and the generation of an introduction likelihood landscape based on patterns of commercial shipping; ballast water moved with these ships is a primary vector for novel species entering New Zealand. In particular, methods for selecting layers for use in Maxent are evaluated, comparing a priori and forward stepwise performance methods. Eight marine and estuarine species on New Zealand’s Unwanted Species Register, including Carcinus maenas and Caulerpa taxifolia, were considered. This model is intended to be a method that can be applied to other locations, including western North America, and modified to reflect changing climatic and socioeconomic landscapes, which could influence invasion risk.

Mason Earles
FIRE, DROUGHT, AND CARBON STORAGE IN MID-ELEVATION SIERRAN FORESTS
Graduate Group in Ecology
Mid-elevation Sierran forests are at a transition point. Fire exclusion has increased abundance of shade tolerant species such as white fir (Abies concolor). Such species are often found growing beneath the canopy of historically dominant species such as ponderosa pine (Pinus ponderosa). Moreover, white fir is less fire and drought tolerant than ponderosa pine. Consequently, mid-elevation Sierran forests are transitioning from drought tolerant pine forests with relatively few large diameter trees, consisting of an open understory maintained by frequent fire, to a forest in which drought may become a more prominent disturbance and fire occurs less frequently but more severely. Consequently, carbon storage capacity of mid-elevation Sierran forests in the 21st century will be controlled by fire (or its absence) and drought, along with management actions such as thinning. We conceptually model how thinning, drought, and fire can interact to drive such a transition and associated carbon storage capacity. We show how in white fir dominated forests drought and competition can reduce carbon storage capacity, such that less carbon is stored than in pine dominated forests undergoing frequent fire. Contrary to prior findings, restoring mid-elevation Sierran forests to an active fire regime may align with long-term carbon sequestration objectives.

James Farlin
INFLUENCE OF SYNOPTIC WEATHER EVENTS ON THE ISOTOPIC COMPOSITION OF ATMOSPHERIC MOISTURE IN A COASTAL CITY OF THE WESTERN UNITED STATES
Graduate Group in Ecology 
Synoptic weather events are known to strongly influence the isotope composition of precipitation in continental locations. In this study we present hourly values of water vapor isotopologues measured over a 30-day period in locally extreme weather conditions in San Diego, California, U.S.A. We investigate how atmospheric and hydrological processes influence water vapor isotopologues using a isotope enabled GCM model (IsoGSM).  Combining measurements and IsoGSM simulation, we demonstrate that convective mixing of marine and continental air masses are responsible for the isotopic variation of near-surface water vapor in this coastal location, which is most pronounced during Santa Ana winds. We demonstrate that a two-source mixing approach (Keeling plot) can reliably be used to estimate the isotopic composition of the source moisture, and from that, to infer the moisture’s origin that contributes to the atmospheric moisture content in southern California.  The study is unique because it combines large-scale isotope GCM modeling with high resolution isotope data to disentangle the control of atmospheric and hydrologic processes on the atmospheric humidity in an extratropical climate. Our results demonstrate using single-point, ground-based isotope observations as a complementary resource to existing satellite isotope measurements for constraining isotope-enabled GCMs in investigation of the atmospheric water cycle.

Rosemary Hartman
FACILITATION FROM FISH, FROGS, AND FISHERMEN: FOREVER FRIENDS?
Graduate Group in Ecology
Invasive species are one of the leading conservation challenges facing world biodiversity, but many species are intentionally stocked despite effects on native species. Non-native trout reduce the probability of occupancy of mountain lakes by the threatened frog, Rana cascadae; however, some lakes with trout do support breeding populations of these frogs. To facilitate healthy populations of frogs in the area, managers should take both frog habitat availability and fishing pressure into account when choosing which lakes to stock. I addressed this by surveying recreational users of the Trinity Alps Wilderness to see what proportion of users were fishing and which lakes they were using. Only 23% of respondents were fishing, with fishing pressure concentrated at specific lakes.  I measured the extent of probable refuge habitat for frogs in lakes in the Trinity Alps and built a  model relating habitat variables to probability of breeding frogs. Factors most strongly related to fish-frog coexistence included large areas of emergent vegetation, low bank slope, nearby frog populations, and presence of western toad (Bufo boreas). Both numbers of anglers and refuge habitat for frogs should be used to decide which lakes to target for trout stocking or removal when formulating basin-wide management plans.

Ashley Hawkins
FOREST PATHOGENS AND THE COEXISTENCE OF DOUGLAS-FIR AND WHITE FIR
Plant Pathology Graduate Group
Forest pathogens, insects, and abiotic factors can accelerate tree mortality, increase stand structural heterogeneity, and alter tree community composition.  In northern California, the canopy trees Abies concolor (white fir) and Pseudotsuga menziesii (Douglas-fir) co-occur and vary in shade tolerance and regenerative abilities following disturbance.  Field observations suggest white fir mortality and turnover exceeded that of Douglas fir, and native pathogens may be important drivers in the absence of fire.  In study sites ranging from 4-10 ha abundances and size class distributions of canopy trees, presence of pathogens, bark beetles, and causes of tree mortality were determined.  Canopy gaps and closed canopy forests were sampled for overstory species composition, cause(s) of death of gapmaker trees, and regeneration of white fir and Douglas-fir.  For trees 10 cm dbh, root-rot fungi accounted for significantly higher mortality and gap formation in white fir relative to Douglas-fir.  Relative seedling/sapling density of Douglas-fir was higher in pathogen-induced canopy gaps than closed-canopy forest.

Katie Holzer
FROG USE OF URBAN AND AGRICULTURAL LANDSCAPES IN VIETNAM
Graduate Group in Ecology 
Urban areas are growing rapidly in the lowlands of Southeast Asia, and the impacts of this growth on wildlife are very little studied. A plethora of amphibians are present in these areas, and their use of urban and agricultural water bodies may greatly impact their persistence. We conducted a survey of frog breeding in and around the three largest cities in Vietnam. For each city we examined water bodies in urban, suburban, and agricultural landscapes and assessed local and landscape factors that may affect amphibian performance. We found that all species present during the survey were breeding in all three land-use types, but that the average richness per water body and proportion of water bodies occupied decreased with increasing urbanization. Urban frogs were found breeding in empty lots, park lakes, construction sites, and fountains. The factors that best predicted species richness in urban and suburban areas were: edge type (natural vs. impervious), amount of surrounding upland habitat, and presence of shallows. These results show that lowland amphibians can live in large cities if appropriate habitat is provided, and that management decisions, such as paving water body edges, can greatly affect the persistence of these species in human-dominated landscapes.

Alison Marklein
PLANT-MICROBE COMPETITION FOR NUTRIENTS IN TERRESTRIAL ECOSYSTEMS 
Graduate Group in Ecology 
Nitrogen (N) and phosphorus (P) limit carbon storage in terrestrial ecosystems. Decomposition of leaf litter is the primary mechanism of nutrient recycling in forests, supporting the majority of growth. Understanding biological and environmental controls on mineralization will enable predictions of forest nutrient limitation. My research asks: is plant-microbe competition for nutrients facilitative, competitive, or neutral? I developed a model with four compartments (plant, litter, microbe, and inorganic) and tracked N and P in each. In this model, plants acquire nutrients via resorption from senescing leaves, root uptake, and N fixation. Plants lose nutrients that are not resorbed during litterfall. Microbes acquire nutrients via litter decomposition. Using this model, I analyzed the relationship between plant and microbe nutrient use to understand strategies of plant and microbe nutrient acquisition. Additionally, I performed a meta-analysis of N and P mineralization in forests to test my question. I compared mineralization N/P ratios with litter stoichiometry across temperate and tropical forests. The N/P of mineralization scales at a slope close to unity relative to initial litter. Litter and mineralization N/P in tropical forests is higher than temperate forests. This fits with ecological theory: tropics tend to be P limited and temperate systems, N limited. The N/P of mineralization in the tropics is higher than microbes, but temperate forests and microbes are comparable. This research suggests that microbes and plants compete for N in temperate ecosystems and P in tropical ecosystems.

Scott Morford 
CROSS-SCALE INVESTIGATIONS OF ECOSYSTEM NITROGEN SUBSIDIES FROM ROCK IN THE PACIFIC SOUTHWEST
Soils and Biogeochemistry Graduate Group
The standard model of the nitrogen (N) cycle suggests new N enters ecosystems solely from the atmosphere, yet nearly all bioavailable N in the earth system is found in geologic reservoirs. Rock weathering has been implicated as a primary N input pathway in some forest ecosystems, but its widespread importance remains uncertain. Two of the primary challenges to integrating rock N into models of N cycle are 1) quantifying the extent of rock N reservoirs across landscapes, and 2) determining the removal of rock N from soil minerals during pedogenesis. Here, I present results from regional scale investigations of rock N reservoirs and pedon scale quantification of mineral N weathering in soil. Results indicate that N-rich parent materials are both common and widely distributed across ecosystems and suggest that more than a third of land area may receive substantial N subsidies from rock. At the pedon scale, N removal from primary minerals during weathering indicates that between 50 – 90% of ecosystem N could be derived from rock. Together these data suggest that rock N could be an important N source to ecosystems at regional to landscape scales and could contribute to enhanced carbon sequestration in some ecosystems.

Jason Riggio 
THE SIZE OF SAVANNAH AFRICA: A LION’S (PANTHERA LEO) VIEW
Graduate Group in Ecology
African savannahs comprise 13.5 million km2 and encompass most of the present range of the African lion (Panthera leo). Using high-resolution satellite imagery and human population density data we define lion areas, places that likely have resident free-ranging lion populations. In 1960, 11.9 million km2 of these savannahs had fewer than 25 people per km2. The comparable area shrank to 9.7 million km2 by 2000. The current extent of free-ranging lion populations is 3.4 million km2 or about 25 % of savannah area. Habitats across this area are fragmented; all available data indicate that between 32,000 and 35,000 free-ranging lions live in 67 lion areas. Although these numbers are similar to previous estimates, they are geographically more comprehensive. There is abundant evidence of widespread declines and local extinctions. Under the criteria we outline, ten lion areas qualify as lion strongholds: four in East Africa and six in Southern Africa. Approximately 24,000 lions are in strongholds, with an additional 4,000 in potential ones. However, over 6,000 lions are in populations of doubtful long-term viability. Lion populations in West and Central Africa are acutely threatened with many recent, local extinctions even in nominally protected areas.

Chelsea Rochman
DISCARDED PLASTICS AND PRIORITY POLLUTANTS: A MULTIPLE STRESSOR IN MARINE HABITATS  
Graduate Group in Ecology 
Discarded plastics are a global environmental problem across several habitats. In the ocean, plastic pollution is reported globally from coastal to pelagic habitats from the surface waters to the seafloor. Several marine organisms across multiple trophic levels ingest plastic debris. The material itself may pose a threat to marine life, and in addition may be another medium for exposure to priority pollutants. Using recent insights from field and laboratory experiments, I will discuss plastics as a multiple stressor in habitats taking into account the plastic material in addition to priority pollutants that sorb to them. To better understand hazards associated with plastics in aquatic habitats we examined (i) the fate of priority pollutants to the most abundant types of plastic debris and (ii) the toxicological consequences for fish that ingest this material. Significant differences in the sorption of pollutants among plastic types (p<0.001) suggest that some plastics may be less hazardous as marine debris. Significant increases in the body burden of several organic pollutants (p<0.05) in fish exposed to plastic via a dietary exposure suggest that plastic is another pathway for exposure to toxicants. Lastly, histological changes in exposed fish suggest that plastic ingestion is hazardous.

Katherine Smith
SHOULD I STAY OR SHOULD I GO: TIDE AVOIDANCE AND MOVEMENT RATES OF THE SALT MARSH HARVEST MOUSE
Graduate Group in Ecology 
Understanding how behavioral plasticity helps animals cope with human-induced environmental heterogeneity is crucial because organisms are under increasing pressure from habitat degradation and climate pressure.  The salt marsh harvest mouse (Reithrodontomys raviventris) is an endangered species that evolved in tidal marshes and is also found in human-created diked habitats.  Our objectives were to identify the primary type of refuge used by this species during inundation of its habitat by sea water at high tide (i.e., emergent vegetation or areas of higher elevation), and to compare movement rates of salt marsh harvest mice living in tidal and diked wetlands.  We used radio telemetry to observe mice in tidal and diked wetlands during high tides associated with the full and new moons. Results indicate that, mice predominantly remain in emergent vegetation above water during high tides.  Nocturnal movement rates did not differ between diked and tidal wetlands. However, differences between nocturnal and diurnal movement rates within wetland types suggest that mice living in diked areas may have modified their behavior to take advantage of the lack of tidal inundation by sleeping through the day.

Robert Walsh
EMERGENT AQUATIC INSECTS SUPPORT UPLAND CONSUMERS: ISOTOPIC TRACKING OF AQUATIC PRODUCTION IN A RIPARIAN FOOD WEB 
Graduate Group in Ecology
Access to multiple prey types may help buffer generalist consumers against declines of any one type.  In riparian ecosystems, emergent aquatic insects represent a potentially  important resources subsidy for breeding songbirds.  Aquatic insect may be especially critical in California’s Mediterranean climate, where the lack of spring and summer rainfall limits the productivity of terrestrial insects on which birds also rely.  We investigated the extent to which emergent aquatic insects act as a resource subsidy to breeding songbirds and tested whether they were more heavily relied upon late in the nesting season to compensate for terrestrial insect declines.  Tree Swallows nesting up to a half-kilometer away from water took aquatic insects as prey, and nestling swallow diets showed up to 40% reliance on aquatic insects based on compound-specific isotope analysis of feather amino acids.  Differences in diet based on distance to water and date of nest initiation were less marked than predicted, but aquatic insect use increased over the course of the breeding season.   Thus, despite relatively limited landscape coverage, streams play a disproportionately important role in supporting riparian breeding birds via aquatic insect resource subsidies.

Caitlin Wells 
SEX DIFFERENCES IN PLAY BEHAVIOR, PERSONALITY, AND PHILOPATRY IN GOLDEN-MANTLED GROUND SQUIRRELS (CALLOSPERMOPHILUS LATERALIS)
Graduate Group in Ecology
At the taxon level, the tendency to disperse has been associated with sex: in mammals, males tend to leave their natal area and females tend to remain philopatric, a phenomenon called sex-biased dispersal. At the individual level, the tendency to disperse has been associated with personality: risk-taking, social, and/or aggressive individuals tend to leave their natal area, a phenomenon called personality-dependent dispersal. However, the link between these two phenomena — whether sex biases in dispersal may be driven by sex biases in personality — has not been explored. In 2011 and 2012, I observed a population of golden-mantled ground squirrels (GMGS, Callospermophilus lateralis), a small mammal that exhibits sex-biases in juvenile dispersal, to determine if it also exhibits sex-biases in juvenile personality. I found that juvenile female GMGS vary in personality, along a continuum from socially aggressive/ risk-taking to socially docile/ risk-averse; in contrast, juvenile male GMGS are uniformly risk-taking. These behavioral traits may reflect philopatric tendency at the individual level, with implications for the formation of matrilines and the evolution of sociality in mammals.

Boon-Ling Yeo
SYNERGIES BETWEEN NUTRIENT TRADING SCHEME AND THE NEW ZEALAND GREENHOUSE GAS (GHG) EMISSIONS TRADING SCHEME (ETS) IN THE LAKE ROTORUA CATCHMENT
Graduate Group in Ecology              
Agricultural production intensity affects both nutrient and greenhouse gas (GHG) emissions. Environmental policy designed to reduce one type of pollution may have complementary effects on the other type. This paper explores this issue in the Lake Rotorua catchment in New Zealand (NZ) using an agro-environmental economic model, NManager. The Regional Council and NZ government plan to: implement a nutrient trading scheme (NTS) to reduce nutrient discharges to the lake, focusing on non-point sources such as farmland; and include the agricultural sector into the GHG emissions trading scheme (ETS), respectively. Potential abatement costs, total cost savings, and environmental impacts of agricultural production are modeled in three scenarios: inclusion of agriculture in (1) the NTS only; (2) the NZ ETS only; and (3) both the NTS and NZ ETS concurrently. The findings indicate that the: (1) total level of GHG mitigation is higher when both policies are implemented compared to when only one policy is implemented; (2) nutrient discharge and GHG emission permit prices are inversely related; and (3) total economic profit loss from pollution abatement is lower when GHG emissions and nutrient runoffs are managed concurrently compared to the sum of economic profit loss of regulating each type of pollution separately.

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