The Ecological Impacts Of Nitrogen Deposition: Insights From The Carnivorous Pitcher Plant Sarracenia purpurea

Transcription

1 The Ecological Impacts Of Nitrogen Deposition: Insights From The Carnivorous Pitcher Plant Sarracenia purpurea Nicholas J. Gotelli Department of Biology University of Vermont Burlington, VT U.S.A.

2 Nitrogen oxides NO x Burning of Fossil Fuels Nitrate N0 3 Ammonium NH 4 Use of Synthetic Fertilizers

3 Teragrams of Nitrogen Total anthropogenic N fixed 100 Natural range 50 0 Fertilizer NO x Year

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5 Sarracenia purpurea The Northern Pitcher Plant

6 Population Size Effects of N Deposition Individual Altered morphology Changes in reproduction, survivorship Population Increased long-term extinction risk Changes in short-term dynamics Community Changes in abundance and composition Proteomic early-warning indicators Year AR OLS

7 Effects of N Deposition on Carnivorous Plants Life History Effects on Individuals Effects on Populations Effects on Communities The Role of Ecologists

8 Effects of N Deposition on Carnivorous Plants Life History Effects on Individuals Effects on Populations Effects on Communities The Role of Ecologists

9 Carnivorous plants: wellknown, but poorly studied

10 Carnivory in plants Phylogenetically diverse Morphological, chemical adaptations for attracting, capturing, digesting arthropods Common in low N habitats Poor competitors for light, nutrients

11 The Northern Pitcher Plant Sarracenia purpurea Perennial plant of low-n peatlands Lifespan y Arthropod prey capture in waterfilled pitchers Diverse inquiline community in pitchers

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14 Sarraceniopus gibsoni Wyeomyia smithii The Inquilines Blaesoxipha fletcheri Habrotrocha rosa Metriocnemus knabi

15 Inquiline food web

16 Phyllodia Flat leaves No prey capture High concentration of chlorophyll, stomates Photosynthetically more efficient than pitchers

17 Flowering Stalks Single stalk per rosette Flowering after 3 to 5 years Bumblebee, fly pollinated Short-distance dispersal of seeds

18 Leaf Senescence Leaves persist 2-3 years Production of new leaves in following spring Annual increase in rosette diameter

19 Effects of N Deposition on Carnivorous Plants Life History Effects on Individuals Effects on Populations Effects on Communities The Role of Ecologists

20 Anthropogenic N additions alter growth and morphology

21 Nutrient Treatments Distilled H 2 0 Micronutrients Low N (0.1 mg/l) High N (1.0 mg/l) Low P (0.025 mg/l) High P (0.25 mg/l) N:P(1) Low N + Low P N:P(2) Low N + High P N:P(3) High N + Low P Nutrient Source: Micronutrients: Hoaglands N: NH 4 Cl P: NaH 2 PO 4

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23 Anthropogenic N additions alter growth and morphology Increasing N

24 Effects of Anthropogenic N additions Increased production of phyllodia Phenotypic shift from carnivory to photosynthesis Increased probability of flowering

25 Contrasting effects of anthropogenic N vs. N derived from prey

26 Wakefield, A. E., N. J. Gotelli, S. E. Wittman, and A. M. Ellison Prey addition alters nutrient stoichiometry of the carnivorous plant Sarracenia purpurea. Ecology 86:

27 Food Addition Experiment Ecological press experiment Food supplemented with house flies Treatments: 0, 2, 4,6, 8,10,12, 14 flies/week Plants harvested after one field season

28 Food additions do not alter growth and morphology Increasing prey

29 N uptake increases with food level

30 P uptake increases with food level

31 N:P ratio decreases with added food

32 Altered N:P ratios suggest P limitation under ambient conditions Ambient P limitation (Koerselman & Meuleman 1996, Olde Venternik et al. in press)

33 Anthropogenic N additions alter growth and morphology Increasing Atmospheric N

34 Food additions do not alter growth and morphology Increasing prey

35 Contrasting effects of anthropogenic and natural sources of N Anthropogenic N Altered N:P ratios Morphological shift Reduction in prey uptake Prey N Uptake, storage of N & P No morphological shifts Continued prey uptake

36 Although Sarracenia has evolved adaptations for low N environments, chronic N deposition may have caused populations to be currently limited by P, not N. Nitrogen Nitrogen, Phosphorus, other elements, micronutrients

37 Effects of N Deposition on Carnivorous Plants Life History Effects on Individuals Effects on Populations Effects on Communities The Role of Ecologists

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40 Study Sites

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43 Demography survey 100 adult, juvenile plants tagged at each site Plants censused and measured each year Seed plantings to estimate recruitment functions

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47 Recruits Juveniles Adults Flowering Adults Sarracenia matrix model

48 Recruits Juveniles Adults Flowering Adults

49 Matrix Transition Model n t+1 = An t Population vector at time (t + 1) Transition matrix Population vector at time (t)

50 Population Projections Site r individuals/individual year Doubling Time Hawley Bog y Molly Bog y Global human population ~ 50 y

51 How do N and P concentrations affect population growth of Sarracenia?

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53 Nutrient Addition Experiment 10 juveniles, 10 adults/treatment Nutrients added to leaves twice/month Nutrient concentrations bracket observed field values Nutrient treatments maintained 1998, 1999 Press experiment

54 Nutrient Treatments Distilled H 2 0 Micronutrients Low N (0.1 mg/l) High N (1.0 mg/l) Low P (0.025 mg/l) High P (0.25 mg/l) N:P(1) Low N + Low P N:P(2) Low N + High P N:P(3) High N + Low P Nutrient Source: Micronutrients: Hoaglands N: NH 4 Cl P: NaH 2 PO 4

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56 Effects of N additions Increased production of phyllodia Increased probability of flowering Decreased juvenile survivorship

57 L L M H H

58 Effects of Nitrogen on Demography: Results Population growth rates respond to different N and P regimes Population growth rate decreases in response to increasing N Population growth rate decreases in responses to increasing N:P

59 Modeling Long-term Environmental Change Observed N Deposition Time Series Modeling Long-term Forecast N(t) Transition Function Transition Matrix (t) Matrix Multiplication Population Time Series Extinction Risk Time to Extinction Population Structure (t)

60 Modeling Long-term Environmental Change Observed N Deposition Time Series Modeling Long-term Forecast N(t) Transition Function Transition Matrix (t) Matrix Multiplication Population Time Series Extinction Risk Time to Extinction Population Structure (t)

61 N monitoring National Atmospheric Deposition Program NH 4, NO 3 measured as mg/l/yr Annual data Monitoring sites Shelburne, VT Quabbin, MA

62 Quabbin, MA Shelburne, VT NH 4 N0 3

63 Quabbin, MA Shelburne, VT NH 4 N0 3

64 Regression Models Ordinary Least Squares (OLS) N t = a + bt + e First-order autoregressive (AR-1) N t = a +bn t-1 + e

65 N (mg/l/y) N (mg/l/y) N (mg/l/yr) N (mg/l/y) Quabbin (AR-1) Shelburne (AR-1) b = b = b = b = b = b = Year Year Quabbin (OLS) Shelburne (OLS) b = b = b = b = b = b = Year Year

66 Modeling Long-term Environmental Change Observed N Deposition Time Series Modeling Long-term Forecast N(t) Transition Function Transition Matrix (t) Matrix Multiplication Population Time Series Extinction Risk Time to Extinction Population Structure (t)

67 Modeling Demographic Transitions as a Function of Nitrogen

68 Modeling Long-term Environmental Change Observed N Deposition Time Series Modeling Long-term Forecast N(t) Transition Function Transition Matrix (t) Matrix Multiplication Population Time Series Extinction Risk Time to Extinction Population Structure (t)

69 Matrix Transition Model (changing environment) n t+1 = A t n t Population vector at time (t + 1) Sequentially changing transition matrix at time (t) Population vector at time (t)

70 Estimated population size Stage Recruits 1500 Number of individuals Juveniles 23,500 Non-flowering Adults 1400 Flowering Adults 500

71 Massachusetts Forecast Scenario Annual % Change P (ext) at 100 y Time to ext (p = 0.95) Best case -4.7% 0.00 > 10,000 y No change 0.0% y Small increase 1% y Worst case 4.7% y

72 Vermont Forecast Scenario Annual % Change P (ext) at 100 y Time to ext (p = 0.95) Best case -2.2% > 10,000 y No change 0.0% y Small increase 1.0% y Worst case 2.2% y

73 Population Size Projected Population Dynamics AR OLS Year

74 Effects of N Deposition on Carnivorous Plants Life History Effects on Individuals Effects on Populations Effects on Communities The Role of Ecologists

75 Sarracenia Nutrient Feedback Loop Arthropod Prey Atmospheric Deposition Inquiline Community Pitcher Nutrient Pool [N,P] Plant Growth

76 Sarracenia Nutrient Feedback Loop Arthropod Prey Atmospheric Deposition Inquiline Community Pitcher Nutrient Pool [N,P] Plant Growth

77 Sarracenia Nutrient Feedback Loop Arthropod Prey Atmospheric Deposition Inquiline Community Pitcher Nutrient Pool [N,P] Plant Growth

78 Sarracenia Nutrient Feedback Loop Arthropod Prey Atmospheric Deposition Inquiline Community Pitcher Nutrient Pool [N,P] Plant Growth

79 Four-level Multi-Factorial Atmospheric N (8 levels) Prey supplement (yes,no) Top predator removal (yes,no) Nutrient exchange with plant (unmanipulated, isolated, control) Experiment

80 Nutrient exchange with the plant and top predators affect food web structure

81 Sarracenia Nutrient Feedback Loop Arthropod Prey Atmospheric Deposition Inquiline Community Pitcher Nutrient Pool [N,P] Plant Growth

82 Inquilines Nutrients Manipulate [N], [P] in leaves Orthogonal regression design Establish initial [] in a pulse experiment

83 Response Surface Experimental Design [P] [N]

84 Null Hypothesis [P] [N]

85 Community Regulation of Nutrients [P] [N]

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87 Sarracenia Nutrient Feedback Loop Arthropod Prey Atmospheric Deposition Inquiline Community Pitcher Nutrient Pool [N,P] Plant Growth

88 Nutrients Inquilines dn f ( N, I, t) dt di g( I, N, t) dt

89 Sarracenia as a model system for studying eutrophication

90 Experimental enrichment and ecosystem collapse State change Prey Addition Eutrophic Collapse

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92 Proteomic biomarkers as early warning indicators of state changes

93 Species Profiles of Top 30 Identified Proteins when Searching NRP NCBI Indexed Database Unmanipulated Controls

94 Species Profiles of Top 30 Identified Proteins when Searching NRP NCBI Indexed Database Unmanipulated Controls

95 Species Profiles of Top 30 Identified Proteins when Searching NRP NCBI Indexed Database

96 Effects of N Deposition on Carnivorous Plants Life History Effects on Individuals Effects on Populations Effects on Communities The Role of Ecologists

97 Burning of Fossil Fuels Use of Synthetic Fertilizers

98 Teragrams of Nitrogen Total anthropogenic N fixed 100 Natural range 50 0 Fertilizer NO x Year

99 Ecology Environmental Science

100 Reasons for Studying Ecology

101 Reasons for Studying Ecology Natural History

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103 Reasons for Studying Ecology Natural History Field Studies & Experiments

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105 Reasons for Studying Ecology Natural History Field Studies & Experiments Statistics & Data Analysis

106 0.05 Population Growth Rate (Deterministic) 0.00 r Distilled Micros Low N High N Low P High P NP (2) NP (1) NP (3)

107 Reasons for Studying Ecology Natural History Field Studies & Experiments Statistics & Data Analysis Modeling

108 Population Size dn dt f ( N, I, t) Arthropod Prey Atmospheric Deposition di dt g( I, N, t) Inquiline Community Pitcher Nutrient Pool [N,P] AR OLS Plant Growth Year

109 Reasons for Studying Ecology Natural History Field Studies & Experiments Statistics & Data Analysis Modeling Collaboration

110 Aaron M. Ellison Harvard Forest

111 Conclusions Anthropogenic deposition of N is a major ecological challenge

112 Conclusions Anthropogenic deposition of N is a major ecological challenge Carnivorous plants in ombrotrophic bogs are a model system

113 Conclusions Anthropogenic deposition of N is a major ecological challenge Carnivorous plants in ombrotrophic bogs are a model system Individual response plants alter morphology and growth in response to N:P ratios

114 Conclusions Anthropogenic deposition of N is a major ecological challenge Carnivorous plants in ombrotrophic bogs are a model system Individual response plants alter morphology and growth in response to N:P ratios Population response N and P environments affect population growth rate

115 Conclusions Anthropogenic deposition of N is a major ecological challenge Carnivorous plants in ombrotrophic bogs are a model system Individual response plants alter morphology and growth in response to N:P ratios Population response N and P environments affect population growth rate Community response Further study of nutrient inquiline feedback loop

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