Land Sparing in Agricultural Landscapes. Charles Palmer Ben Groom Simon Gillings Steve Langton EnvEcon 2018, Royal Society

Transcription

1 Land Sparing in Agricultural Landscapes Charles Palmer Ben Groom Simon Gillings Steve Langton EnvEcon 218, Royal Society

2 2 15 Research Question What were the impacts of the EEC agricultural set-aside programme on a) bird species [abundance, richness, diversity] b) cereal yield in England, between 1994 & 27? % 1 5 Source: DEFRA (27) Compulsory and actual rates of EEC set-aside, Compulsory rate (%) Actual rate (%)

3 Index (197 = 1) Populations of wild birds, UK Mandatory set-aside first implemented (1993) Final year of mandatory setaside requirement (27) , pop change: 12 1 Tree sparrow: -94% 8 6 Corn bunting: -9% 4 2?? Woodpigeon: +125% All species All (13) Unsmoothed data Farmland birds Generalist (7) Unsmoothed data Farmland birds All (19) Unsmoothed data Farmland birds Specialist (12) Unsmoothed data Jackdaw: +136% Source: RSPB, BTO, JNCC, DEFRA Note: graph shows unsmoothed trends; figures in legend brackets are number of species

4 Q1: Does set-aside affect biodiversity? Positive effect due to (Areté, 28): Prohibition of use of herbicides & pesticides No-intervention on set-aside land Henderson et al., (2); Firbank et al., (23); Gillings et al., (21), etc. provide empirical support for a positive effect on abundance yet Cross-sectional data Failure to control for unobserved determinants of bird abundance / diversity Effects expected to vary according to, e.g.: Type of set aside (fallow vs. non food; rotational vs. non-rotational) Vegetative cover & management practices Site-specific conditions, e.g. steepness of slopes, climatic conditions

5 Ecological thresholds Points of rapid change in ecological properties (Evans et al., 217): Many taxa respond in non-linear ways to habitat loss & fragmentation Thresholds below which species become significantly more sensitive to habitat loss, due to e.g. edge effects & # patches, ~ 3-4% of original habitat (Andrén, 1994; Muradian, 21; Yin et al., 217)

6 Ecological thresholds: birds in Brazil s Atlantic forest Source: Morante-Filho et al. (215)

7 Ecological thresholds Points of rapid change in ecological properties (Evans et al., 217): Many taxa respond in non-linear ways to habitat loss & fragmentation Thresholds below which species become significantly more sensitive to habitat loss, due to e.g. edge effects & # patches, ~ 3-4% of original habitat (Andrén, 1994; Muradian, 21; Yin et al., 217) Do thresholds exist for habitat gain? Or are there irreversible impacts & hysteresis

8 Q2: Does set aside affect yields? UK cereal yields, Possible Responses: i) Extensive margin: low quality land in set-aside ii) Intensive margin: Input mix Source: University of Reading Mandatory set-aside first implemented (1993) Final year of mandatory set-aside requirement (27)

9 Data Bird Data (all birds) Land Use: (uncropped set-aside)

10 Data Bird Data (all birds) Land Use: (uncropped set-aside) 1k 1k 1k 1k 1k

11 Species Abundance All Species Farm Specialists Farmland Species

12 Species Richness (Number of species) All Species Farmland Species Farm All Species Specialists Farmland non Farmland Species Farmland Specialists non-spec.

13 Species Diversity Shannon Index = p i lnp i n i= All Species Farm Specialists Farmland Species

14 Wood Pigeon Starling Willow Warbler Nuthatch

15 Empirical strategy Final models, balanced panel, clustered at the region level: Fixed effects (1k by 1k grid level): i; Year, t (T = 13) fixed effects Year, t (T = 13) by region (3, 1k by 1k) interactions

16 Empirical strategy Abundance 1 (log-linear): ln(#birds), set aside levels (ha), other land uses (ha) n R T ln(#birds) it = a + Setaside it + l landuse lit + δ rt D t D r + i + t + it H l=1 r=1 t=1 Abundance 2 (log-linear, non-parametric in setaside to identify thresholds): ln(#birds), set aside (H hectare bins ) n R T ln(#birds) it = a + h DSet hit + l landuse lit + δ rt D t D r + i + t + it h=1 l=1 r=1 t=1 Model 3 4: Species Richness (log-linear, non-parametric) Model 5 6: Biodiversity (Shannon index), (log-linear, non-parametric) Model 7: Individual species numbers (b), Fixed Effects, FE Poisson n #birdtype bit = a + b set aside bit + l landuse lit + δ rt D t D r + i + t + it l=1 r=1 t=1 R T

17 Species Abundance (Log-linear model) ALL FALL FSPEC ALL FALL FSPEC ALL FALL FSPEC Setaside.115*.12* **.159***.137*.178***.2**.1 Wheat Maize -.31* -.53* -.65* -.337* -.52* -.89** Winter barley -.125* -.2* * -.238* -.23 Spring barley Oats Other cereal Temp. grass Other grass Woodland * Other land Oil seed rape (OSR) OSR setaside.227** Peas beans * -.168* Stockfeed.719***.833** **.733*.472 Sugar beet Fallow Linseed set-aside Linseed Samples (n).51615**.59373*.7673*.537**.6852*.7987* Samples-sq ** * -.497* -.325** -.451* Constant 9.59*** 8.53*** 7.37*** 9.56*** 8.41*** 7.25*** 1.23*** 9.36*** 7.59*** Grid FE Y Y Y Y Y Y Y Y Y Year FE Y Y Y Y Y Y Y Y Y Region*Yr FE N N N N N N Y Y Y R-sq N Note: * p<.5, ** p<.1, *** p<.1; standard errors clustered at regional level; ALL, FALL and SPEC denotes all bird species, all farmland bird species, and all farmland specialist bird species, respectively.

18 Species Abundance (Log-linear model) Non-Farmland Non-Spec. Non-Farmland Non-Spec. Non-Farmland Non-Spec. Setaside.15* * *.24** Wheat Maize Winter barley * -.235* Spring barley Oats Other cereal Temp. grass Other grass Woodland Other land Oil seed rape (OSR) OSR setaside.282** Peas beans * Stockfeed.642***.975***.475**.761** Sugar beet Fallow Linseed set-aside Linseed.6942***.95476**.67894***.92847** Samples (n) -.497*** ** -.493*** ** Samples-sq *** *** *** *** *** *** Constant.15* * *.24** Grid FE Y Y Y Y Y Y Year FE Y Y Y Y Y Y Region*Yr FE N N N N Y Y R-sq N Note: * p<.5, ** p<.1, *** p<.1; standard errors clustered at regional level

19 Species Abundance: All birds: Non-parametric results 2ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha Baseline: 1-1 ha Baseline: 1-2 ha Wald Tests Reject Ho: set2 = setx for X > 5 Reject Ho: set>9 = setx for X <= 9

20 Species Abundance: Farmland birds : Non-parametric results 2ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha Baseline: 1-1 ha Baseline: 1-2 ha Wald Test Fail to Reject Ho: set3 = setx for X < 9+

21 Species Abundance: All birds , South Non-parametric results 2ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha Baseline: 1-1 ha Baseline: 1-2 ha Wald Tests Reject Ho: set2 = setx for X > 5 Reject Ho: set>9 = setx for X <= 9

22 Species Abundance: All birds, Non-parametric results 2ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha Baseline: 1-1 ha Baseline: 1-2 ha Wald Tests Reject Ho: set2 = setx for X > 3 Reject Ho: set>9 = setx for X <= 9

23 Species Abundance: Farmland birds, Non-parametric results 2ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha Baseline: 1-1 ha Baseline: 1-2 ha

24 Species Richness: All Birds

25 Species Richness: Farmland Birds

26 Species Richness: Farm Specialists

27 Species Richness Species (All) Species (Non-Farmland) Species (Farmland) Species (Non-Specialist) Species (Farm Specialists) Setaside.3322***.279*** * -.25 Wheat *.38*.86 Maize -.616** ** Winter barley *** ** ** -.86** -.386* Spring barley Oats -.432* * -.3 Other cereal Temp. grass * -6.1E-5 Other grass e-6.3 Woodland.2695* * * Other land **.1739**.197 Oil seed rape (OSR) E OSR setaside.5179*.668** E Peas beans -.463*** -.289* *** -.275*** -.47 Stockfeed Sugar beet Fallow Linseed set-aside Linseed *** * ** * -.835* Samples (n) *** *** *** *** *** Samples-sq *** *** *** *** *** Constant *** *** *** *** *** Grid FE Y Y Y Y Y Year FE Y Y Y Y Y Region*Yr FE Y Y Y Y Y R-sq N Note: * p<.5, ** p<.1, *** p<.1; standard errors clustered at regional level

28 Species Richness: All birds, Non-parametric results 2ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha Baseline: 1-1 ha Baseline: 1-2 ha

29 Species Richness: Generalists Non-parametric results 2ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha Baseline: 1-1 ha Baseline: 1-2 ha

30 Species Richness: Farm Generalists Non-parametric results: 2ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha Baseline: 1-1 ha Baseline: 1-2 ha

31 species Northing all shanall Northing shanfall Biodiversity: Shannon Index All birds Farmland Easting Easting Richness 65.5 Abundance Easting Easting

32 Biodiversity (Shannon Index) Shannon Index = p i lnp i All birds, n i=1 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha 2ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha Baseline: 1-1 ha Baseline: 1-2 ha

33 Biodiversity (Shannon Index) Shannon Index = p i lnp i All birds, pre 21 n i=1 2ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha 3ha 4ha 5ha 6ha 7ha 8ha 9ha > 9ha Baseline: 1-1 ha Baseline: 1-2 ha

34 Yield (very preliminary) Yield Function (Cobb-Douglas, kg/ha) Fixed Effects Fixed Effects (Year*Region) Fixed Effects Fixed Effects (Year*Region) Setaside (ha) Crop Protection ( ) Fertilizer ( ).53469***.53527***.74759***.7399*** Agricultural Area (ha).13533***.16278*** *** *** Arable Area (ha).19824*** *** *** *** Battese Correction Setaside *** *** * * Crop Protection Fertilizer Cost Agricultural Area ***.54121*** *** *** Arable Area *** *** *** *** One Period Lags Cereals Yield (kg/ha) ** ** Set-aside (ha).51677**.52437** Constant * Grid FE Y Y Y Y Year FE Y Y Y Y Region*Yr FE N Y N Y R-sq N Note: * p<.5, ** p<.1, *** p<.1; standard errors clustered at farm level Contemporaneous Effect: Set-aside not low quality land Lagged Effect: Intensive Margin

35 Discussion Results: set-aside bird abundance, bird species richness, ( ) bird diversity, ( yield) Thresholds: >2 ha required, then >9 Effects concentrated in the South, pre-2 Cost per bird : >9 ha threshold to 29-51/bird (ignoring net change in ag prod) Land sparing: win-win for production & biodiversity in agricultural landscapes post-brexit? Set-aside: small effects Post 222 support to farmers likely to be 1% environmental More targeted activities than set-aside required.

36 EXTRA SLIDES

37 Safe limits of biodiversity loss Source: Newbold et al. (216) Major drivers of loss: habitat conversion to agriculture, degradation, fragmentation (Haddad et al., 215; Newbold et al., 215)

38 Change in agricultural area, India Rainfall & agriculture in India Agricultural land: home to 5% of Europe s bird species (Pain and Pienkowski, 1997) Yet, biodiversity losses also observed in settings where agricultural land is in decline

39 Dataset From RSPB: Farmland birds are an indicator of the general quality of the farmed environment because birds sit near the top of the food chain and trends have been well monitored by the British Trust for Ornithology since 1967 (RSPB). Farmland birds population trends : Tree sparrow -94%; Corn bunting -9%; Turtle dove -89%; Grey partridge -87%; Yellow wagtail -73%; Starling -68%; Linnet - 58%; Lapwing -58%; Yellowhammer -54%; Skylark -51%; Kestrel -35%; Reed bunting - 27%; Whitethroat +5%; Greenfinch +23%; Rook +41%; Stock dove +55%; Goldfinch +64%; Woodpigeon +125%; Jackdaw +136% for time trends in agriculture, (Roser and Ritchie, 217) Introduction Model Dataset Empirical Strategy Results Robustness & Further Results Conclusions

40 Impact of set-aside on cereal yield? Rudel et al. (29): Intensification land sparing (decline in agricultural land)? Find in agricultural land associated with yield at country scale but only where there are grain imports and set-aside programmes Direction of effect Fall in agricultural land intensification? Martinet (214): Land rent framework Farmers: price takers Profit functions & land use: interior solution

41 Martinet (214): policy mix & associated land-use configurations Subsidies to reserve (= set-aside, s), Taxes on inputs to intensive production (τ); least-productive land set-aside first Mandatory setaside? Bourgeon et al. (1992): productive land also set-aside, imposes social cost

42 Northing Robin Corn Bunting Jackdaw Tree Sparrow Easting

43 JD Northing S. CB Corn Bunting = The Absence of Individual Species Easting Jackdaw = 4 35 Starling = Easting Easting

44 Local polynomial smooth Degree: year uncrop_setaside locpoly smooth: uncrop_setaside

45 1.5 2 Shannon Index Linear prediction The Shannon Index in Equally Distributed Species Species Diversity Shannon Index = n i=1 p i lnp i Species species

46 Species Abundance ALL BIRDS OLS Random Effects Fixed Effects Fixed Effects (year*region) Setaside.393***.27***.157***.176*** Wheat.11.49* Maize * -.327* Winter barley * -.173* Spring barley Oats Other cereal Temp. grass.43***.149** Other grass.4** Woodland Other land.61** Oil seed rape (OSR) OSR setaside **.21*.116 Peas beans * Stockfeed.758*.74***.71***.571** Sugar beet.25** Fallow.827* Linseed set-aside.3478* Linseed Samples (n) ***.56679**.54534** Samples-sq ** ** ** Constant *** *** *** *** Grid FE N N Y Y Year FE Y Y Y Y Region*Yr FE N N N Y R-sq N Note: * p<.5, ** p<.1, *** p<.1; standard errors clustered at regional level

47 Species Richness ALL BIRDS OLS Random Effects Fixed Effects Fixed Effects (year*region) Setaside.338*.2777*.2816*.3322* Wheat Maize Winter barley * Spring barley ** Oats * Other cereal Temp. grass Other grass -.64** -.286* -6E Woodland Other land.634* Oil seed rape (OSR) OSR setaside **.4246*.5179* Peas beans -.591** *** ** -.463** Stockfeed.21167**.774**.6154*.5179 Sugar beet.318** Fallow Linseed set-aside Linseed ** * * Samples (n) *** *** *** *** Samples-sq *** *** *** *** Constant *** *** *** *** Grid FE N N Y Y Year FE Y Y Y Y Region*Yr FE N N N Y R-sq N Note: * p<.5, ** p<.1, *** p<.1; standard errors clustered at regional level

48 Individual Species Numbers (model 7) Greenfinch Jackdaw Kestrel Reed Rook Wood Bunting pigeon Set-aside * * R-sq N Yellow Corn Goldfinch Pigeon Lapwing Linnet Wagtail Bunting Set-aside ** R-sq N Skylark Starling Stock Dove Tree Turtle White Sparrow Dove Throat Set-aside ** R-sq N legend: * p<.1; ** p<.5; *** p<.1

49 Robustness checks Balanced-unbalanced Clustering Functional forms Panel causality tests Panel Poisson Region interactions with agro-ecological zone Spatial?

50 What about the UK post-brexit? Current CAP: basic payments to support incomes & environmental efforts; additional efforts compensated via voluntary two-tiered scheme Beyond 222 support could be 1% conditional on environmental efforts (Gove) Contrasting visions, i.e. agricultural (NFU) vs land-use policy (CLA, NT) Post-Brexit trade deals cheaper food imports? Impacts on UK farming concerns re food security Unprofitable farms go bust? rewilding on abandoned farmland % land in ag Any point setting land aside?