Functional Diversity in Integrated Crop Management

Transcription

1 Functional Diversity in Integrated Crop Management William H. Settle University of California, Santa Cruz and UNFAO Community IPM Programme In Asia

2 AGRO-BIODIVERSITY: The Challenge "we know as little about biodiversity in traditional tropical agro-ecosystems as we know about biodiversity in the tropical rainforests" --Vandermeer and Perfecto 1995 "the neglect of agro-biodiversity in the portfolios of lending and development organizations, as well as in treaties and conventions that deal with environmental conservation, is striking." -- The World Bank report, 1996

3 Classification Of Agricultural Systems By Diversity Diversity of Production System Diversity of Species Low High Multi-Field Type Shifting Cultivation Nomadic Pastoralism Traditional Compound Rotational Fallow Savanna Mixed Compound Agribusiness Horticulture Pasture Mixed Alley Farming Crop Rotation From Swift and Anderson 1994 Single-Field Type Home Garden Multi Cropping Alley Cropping Intercropping Plantations & Orchards Intensive Cereal

4 RESEARCH RESULTS Five Year Study of Arthropods In Rice Ecosystems in Indonesia Across Differing Landscapes And Levels of Intensification

5 What Proportion of Species are Important? SPPCODE TROPHIC GUILD FAMILY ORDER TOTAL % CUM RANK sminthurida other detritiv sminthurid collembola entomobrya other detritiv entomobryid collembola delphacida phytophage plantsuc delphacid homoptera linyphiida predator spidweb linyphiid araneae chironomidl other filterfe chironomid diptera lycosida predator spidhunt lycosid araneae isotomida other detritiv isotomid collembola delphacidd phytophage plantsuc delphacid homoptera veliida predator surfbug veliid hemiptera cicadellidg phytophage plantsuc cicadellid homoptera mesoveliida predator surfbug mesoveliid hemiptera cicadellidi phytophage plantsuc cicadellid homoptera chironomidn other filterfe chironomid diptera delphacidi phytophage plantsuc delphacid homoptera chloropidc predator predfly chloropid diptera chironomida other filterfe chironomid diptera cicadellidb phytophage plantsuc cicadellid homoptera veliidi predator surfbug veliid hemiptera ceratopogg predator predfly ceratopogon diptera podopida phytophage plantsuc podopid hemiptera hydrophilidg ceraphronf hydrophilidp predator parasitoid aquapred larvpste hydrophilid coleoptera ceraphronid hymenoptera predator aquapred hydrophilid coleoptera % of Total Abundance % of Total Species 12 = 50% A 1.4% S 43 = 75% A 5.2% S 123 = 90% A 14.7% S 210 = 95% A 25.2% S 6 regions; 16 fields Total = 835 morpho-species

6 And, What Does Important Mean? Fraction of Total Abundance Neutrals 37.8% Number of Species Parasitoids 6.8% Herbivores 22.8% Neutrals Parasitoids 159 (19%) (192 23%) Predators 32.6% Predators 311 (37%) Herbivores 173 (21%) First Cut: Trophic Composition

7 Functional Groups: A Heuristic Tool Series1 Surf Bug Predator Parasitoid Herbivore Neutral Detritiv Leaf Chew Plant Suck Pred Beet Egg Pste Pred Fly AquaPred Filter Feed Spid Web Spid. Hunt Ant Div. Pste Pred Bug Borer Egg Pred Flying Pred Larv. Pste Number of Species per Functional Group

8 Hyper Parasitoids Hypothesized Generalized Rice Food Web PARASITOIDS ARTHROPOD PREDATORS HERBIVORES RICE PLANT CHIRONOMIDS & MOSQUITOES TUBIFICID WORMS MICROCRUSTACEA DETRITIVORES ROTIFERS PROTOZOA PHYTOPLANKTON CO 2 P 2 O 5 NH 4 NO 3 OTHER BACTERIA ORGANIC MATTER

9 Tropical Rice: Three Pathways Support Natural Enemies NATURAL ENEMIES PESTS RICE PLANT FILTER FEEDERS MICRO-ORGANISM CYCLE DETRITIVORES ORGANIC MATTER

10 AS PREDICTED: Adding Organic Matter to the System Boosts populations of Neutrals (Detritus and plankton Feeders) & Predatory Insects Mean insects per square meter Ha ; 12 replications Neutrals Predators Low High Low High Below water Water surface and Plant Canopy Organic Matter Inputs

11 Indications of a Stable System Mean per square meter Neutrals Predator Herbivore Parasitoids Days After Transplanting Parallel Work in China: Dr. Wu Jincai (et al) Jiangsu Agricultural College Zhang Wenqing, Zhongshan University A Community-Level Pattern of Species Assemblage High Levels of Associated Agro-biodiversity A Clear-cut Intrinsic Mechanism Leading to Stable & Robust Pest Suppression

12 Rethinking the Old Paradigm: Vegetative Diversity? or Rather Foodweb Diversity Insectary Plants Trap Crop Crop? Crop Terrestrial Foodweb Irrigated Rice Aqatic Foodweb? Linking Species: Predators / Parasitoids Foodwebs: Not Necess. Coevolved Linking Species: Pests Foodwebs: Not Necess. Coevolved Linking Species: Neutrals Foodwebs: Highly Coevolved

13 Large-scale Factors Affect Intrinsic Mechanisms Indirect Management: Farmers do not Usually Manage Arthropod Biodiversity Directly, They Manage Factors that Affect Arthropods, (Whether they are aware of the impacts or not) SPATIAL SCALE** LANDSCAPE HETEROGENEITY ** WATER MANAGEMENT** PESTICIDES** INTRINSIC ECOLOGICAL MECHANISMS RESIDUE MANAGEMENT** PLANT GENETICS AND DIVERSITY

14 Mean yield: tons/ha Non-Treated Treated Insecticide-Induced Resurgence * Disturbance at the Plot-to-Landscape Level 1093 Mean per square meter a Parasitoid Predator Herbivore Neutrals Untreated b Treated F Carbofuran A Azodrin Days After Transplanting F A F A

15 Landscape Level Influences

16 High Global Disturbance: Large Scale Synchronous Planting Landscape Favors: Long-distance Travelers High Fecundity Relatively Large & Robust Arthropods = Pests Farmer s Plot Rice Dry Fallow Hypothetical Individual Range of Arthropod movement

17 Low Global Disturbance: Non-Synchronous Planting Landscape Favors: Long-lived Generalists (Predators) Highly Efficient Searchers (Parasitoids) Farmer s Plot Rice Dry Fallow Newly Flooded Hypothetical Individual Range of Arthropod movement

18 Large-Scale Synchrony Delays Predator Arrival Time Synchronous Predators Non-Synchronous Proportion of plants Predators present Number of predators per square meter.

19 Large-Scale Synchrony Leads to Lowered Agro-biodiversity Rank-Abundance Curves Log abundance for each species Herbivores Neutrals Parasitoids Predators North-West (Synchronous) Central (non-synchronous) Species Ranking

20 Non-Synchronous Planting Not Only Leads to More Stable Arthropod Ecology, but More Stable Labor Requirements More Stable Input Costs More Stable Harvest Prices Left to their own, Farmers Drift away from Enforced Synchronous plantings

21 Caveats: Cases Where Heterogeneity Does Not Work Well Extreme Fine-scale Heterogeneity (1-5 ha): Tungro Virus Swidden Systems: a case in which high biodiversity is NOT correlated with good pest suppression Areas Subject to High Pesticide Use

22 Arthropod Diversity and Agro-Ecosystem Function Relative Abundance α Richness Function of Pest Suppression Is an Emergent Property resulting from complex interactions of the whole System Species Species Diversity Spatial Distribution β Individual Life Histories Magnitude Arthropod Communities Trophic Relations Timing & Duration Availability Spatial Distribution Timing & Duration Management Environment Resources Type Food Water Refuge Mate Etc. Climate Etc. Structural Habitat

23 Farmer Training

24 The Field Is Our Book

25 Promote Questioning, not Scientific Jargon

26 Conclusion: Research Agenda at the Ecosystem Level -- study agricultural systems within-crop and across a continua of landscapes and management intensities (Build Capacity in-country) -- seek to understand the range of mechanisms (both in terms of nutrient-flow and community dynamics) that support the service in question. -- seek to understand how these mechanisms are affected by large-scale factors that underlie ecosystem function (the ecological context ) -- look to see how what the implications are for policy and management -- take responsibility for educating people in a practical way!

27 Exploring Further Case Studies in Areas of High Natural Biodiversity Kalimantan: helping farmers transition out of Slash & Burn Thailand: Improving Production Systems with the Hill Tribal people on the Border with Burma Mali: Exploring the Relationship Between Rice Cultivation and Natural Wetland Regia in the Niger River Inland Delta

28 Thank You!