Publications: 1980–1989

Abstract: Se analizan 92 muestras de vegetaciones, suelos y técnicas de cultivo en cafetales del estado de Veracruz y estados vecinos. Algunos de los componentes de manejo, tales como niveles de fertilizaciones, podas, chapeos y aplicación de pesticidas, se muestran altamente correlacionados entre sí. El conjunto de técnicas intensivas de cultivo, a su vez, está asociado con las grandes plantaciones y los mayores rendimientos de café. Los rendimientos estimados varían desde 200 kg/ha hasta 8500 kg/ha. A pesar de la existencia de tipos discretos de suelos y clima, así como de asociaciones de árboles de sombra y de frutales intercalados, las correlaciones entre los tipos y las asociaciones fueron débiles excepto cuando las correlaciones se debían a patrones altitudinales. También se notó muy poca relación estadística entre estos factores ecológicos y los rendimientos en café. Las únicas relaciones importantes fueron tendencias hacia bajos rendimientos en presencia de otros frutales intercalados y hacia rendimientos mayores en presencia de algunos árboles de sombra. Las plagas fueron más comunes en las plantaciones que usaban más pesticidas, y las enfermedades por hongos fueron más frecuentes en plantaciones con podas intensas. No se pudo concluir nada firme de la relación entre la condición del suelo (erosión) y varios factores ecológicos y de manejo. Sin embargo, los datos sugieren que algunos elementos de la tecnología intensiva (fertilización) están asociados con las mejores condiciones ecológicas y otros (podas) con las peores.

Abstract: Se presenta un enfoque práctico para incluir factores del medio ambiente en la planeación del uso de la tierra. Se ejemplifica con la región Xalapa, un área de 4750 km² que incluye variadas condiciones ecológicas entre las zonas templada y tropical de México; las principales fuentes de información consultadas fueron: fotografías aéreas, una encuesta de productividad en parcelas de maíz y entrevistas con agricultores y agrónomos de la zona para conocer las técnicas de cultivo empleadas en ella. Sobre la base de un sistema climático-geomorfológico de clasificación de la tierra, identificamos 33 tipos funcionales de tierra y describimos 56 sistemas de uso agrícola. Para cada combinación de tipo de tierra y sistema de uso estimamos ingresos, empleo, costos, producción alimentaria, insumos de químicos agrícolas y niveles de erosión. Esta información nos permitió plantear un juego de optimización con objetivos múltiples para ser usado en planeación. Los usuarios del juego pueden fijar prioridades y, al variar niveles de infraestructura, pueden también examinar los intercambios entre los objetivos de la planeación y las diferentes alternativas de inversión, y políticas de manejo, lo que se reflejará en asignaciones óptimas de tipos de tierra a sistemas de uso. El juego se ilustra con un estudio de los costos ambientales que conllevará el producir más alimentos para la creciente población de la región Xalapa. Se hace también una comparación del uso actual de la tierra con el que la asignación óptima del juego sugiere bajo distintas prioridades. Dentro de esta perspectiva se examinan: 1) la capacidad de sustentación de la región, prestando particular atención a las demandas de la creciente población urbana y rural y 2) el papel que jugaría la tecnología moderna, dirigida, en el aumento de la capacidad de sustentación sin dañar excesivamente el medio ambiente.

Abstract: Se presenta un esquema jerárquico de clasificación e inventario de la tierra (4500 km²) en el centro de Veracruz. El objetivo de la clasificación es definir tipos de tierra que: i) representen las diferentes condiciones ecológicas existentes, ii) permitan entender su comportamiento bajo distintos sistemas de uso de la tierra y, iii) sean rápida, económica y fácilmente identificables. Otros niveles de esta clasificación, sistemas terrestres y paisajes, pueden ayudar en la localización de los tipos de tierra y en la regionalización para la planeación de grandes espacios. Se discute, con resultados, el esquema empleado y se concluye que satisfizo los objetivos planteados.

Abstract: En este trabajo se propone un método sencillo para evaluar la productividad en la planeación del uso de la tierra. El método se basa en una encuesta de más de 300 parcelas de maíz en el centro de Veracruz, y en un muestreo, no destructivo, de plantas de maíz. La productividad de una parcela fue estimada mediante la medición de las alturas y los diámetros de 30 plantas de maíz. De una submuestra surgió la siguiente ecuación para estimar la biomasa aérea de plantas individuales de maíz: biomasa = 45.1 (altura·81 diámetro)1.38. Se encontró una relación muy estrecha entre la producción de las parcelas (kg de peso seco/ha) y la "evapotranspiración realizable" (mm) calculada con los registros de evaporación de tanque y precipitación de las estaciones climáticas en la región: producción = 15.7 (evaporación realizable). La productividad de cada tipo de tierra pudo ser estimada empíricamente mediante el muestreo de una serie de parcelas en cada tipo de tierra. La productividad así estimada fue corregida con respecto a las prácticas de cultivo, las cuales varían de un tipo de tierra a otro. La aplicación de fertilizante nitrogenado fue la única práctica de cultivo con un efecto significativo (la densidad de siembra tuvo también un efecto sobre la productividad del maíz, pero ésta puede ser considerada como parte integral de la respuesta productiva). Varias propiedades del suelo fueron examinadas para determinar su relación con la productividad; la profundidad del suelo resultó la más importante de todas.

Abstract: A small group of scientists and engineers assembled at the East-West Environment and Policy Institute during the summer of 1980 to examine the question “How can environmental concerns be brought into the biomass energy development process?” The state of Hawaii, which has numerous biomass energy developments underway or under consideration, was used as a case study to make the group's thinking more specific and relevant to real-world problems. Energy treefarms and fuel ethanol were given particular attention because of their prominence in current discussions about biomass energy in Hawaii. The group's primary conclusion concerned the need for more effective means of communicating the impact that environmental effects from specific kinds of biomass energy development will have on the quality of human life. It is helpful to cast environmental concerns in terms of broader issues, so energy policymakers, planners, and investors can judge them alongside the numerous other concerns they must weigh in their decisions. Five research areas were identified as deserving further development: (1) a clearinghouse for technical and environmental information on processing options for alcohol stillage waste; (2) an atlas on the amount of land suitable and available for biomass energy farms or plantations in different areas; (3) workshops to give decision makers in energy development a better understanding of environmental issues and how they bear upon their responsibilities; (4) analyses of the economic and environmental benefits and costs to be expected from biomass energy development; (5) means of streamlining environmental regulations for energy development.

Abstract: There is an immense variation in actual and potential fish yields, both within and between different kinds of aquatic tropical ecosystems. The finfish catches from lakes, reservoirs, rivers, continental shelves and coral reefs all fall in approximately the same range of 0.1 to 30 tonnes/km²/year, with most catches falling in the range of 1 to 10 tonnes/km²/year and modal values falling in a range of 3 to 6 tonnes/km²/year. The yields from estuaries and ponds can be considerably higher (up to 120 tonnes/km²/year without supplementary feeding), and the yields from open ocean are considerably lower (.002 to .05 tonnes/km²/year). Within the tropics, the best physical indicator of a fishery's potential yield is water depth, and the best biological indicator is primary productivity. Some ecosystems such as rivers, estuaries and ponds have relatively high fish yields for their primary productivity, presumably because of organic matter inputs. Other ecosystems such as coral reefs and open oceans have relatively low fish yields, presumably because of long food chains. However, no single indicator, including primary productivity, can predict fish yields very precisely. More refined yield assessments will have to be empirical in nature, recognizing the importance of fishing practices in assessing potential yields and giving particular attention to how the composition of fish communities in different habitats is altered by fishing and other human activities.

Abstract: With the advent of extended maritime jurisdictions, new arrangements will be sought between fisheries resource owners and distant-water fishing fleets that may want to share the use of fishery resources. Each party has motives for wanting to exploit the fishery, and each has strengths and weaknesses in doing so. The purpose of this study was to develop a logical process to identify arrangements that are fair and profitable for both parties. As a case study, we examined conflicts and agreements of interest between Indonesia and Japan with respect to arrangements they might have for exploiting Indonesia's tuna. Thirty-seven possible arrangements between the two countries were evaluated by a multinational, multidisciplinary team employing goal analysis, an optimization technique for dealing with multiple objectives. The arrangements differed in the following respects: type of fishing operation (all of them longline, but differing with respect to vessel size and other characteristics); kind of processing (cold storage, canning, or freezer-carrier operations); ownership (Indonesian, joint-venture, or Japanese); base of operation (Indonesia or Japan); participating Japanese sector (small-scale tuna fishermen, medium-scale tuna fishermen, or traders and large-scale fishery companies); and marketing alternatives (fresh fish, frozen fish, or canned-goods markets). Tradeoffs were examined among eleven goals and constraints that might be involved in negotiating an arrangement: capital investment, return on investment, employment, foreign exchange earnings, and technology transfer for Indonesia; capital investment, return on investment, employment, tuna supply, fishermen's profits, and traders' profits for Japan. This study found many points of agreement of interests between the two countries, to the extent that they can share in efficient and profitable fishing, processing, and marketing operations where both parties can enjoy the benefits. In particular, freezer-carrier operations combined with Indonesian-based fishing offer many advantages over the recent fee fishing arrangement. Genuine conflicts of interests also were found in tradeoffs between employment and operating costs and in how the ownership and profits of the operations are shared between the two countries. Although results are preliminary and require further refinement and validation before they can assist with real fishery negotiations, this approach to exploring new options for bilateral fishery arrangements has great potential and should be pursued to the point where it can be utilized in practice.

Abstract: While the stillage waste from ethanol fuel production can be a serious source of water pollution, it can also be a valuable resource from which to recover useful products such as fertilizer, animal feed, or methane gas. Selecting the most appropriate stillage management is a matter of trade-offs between energy, economic, and environmental considerations. There is a need for an information clearing-house on commercial stillage handling processes to assist ethanol fuel developers in matching processes to their needs.

Abstract: A practical approach for the inclusion of environmental factors in land-use planning is presented. The Jalapa region, an area of 4750 km² which embraces a diversity of ecological conditions, is used to illustrate the approach. Data were gathered from aerial photographs, a survey of maize fields and interviews of farmers concerning their cultivation practices. After devising a climatic and geomorphological system of land classification, 33 land types were identified, described and inventoried; 58 land-use systems were identified and described. The descriptions were structured to predict the income, employment, costs, food production, agricultural chemical inputs and erosion that could be expected for each land-use system on each land type. This information was used to devise a multi-objective land-use game for planners. Users of the game may set priorities on their planning objectives, specify the amounts of agricultural services available, and see the effects these have on optimal allocation of the available land of each type among the different possible uses, as well as how well the objectives are satisfied by the allocation. By shifting objective priorities and varying infrastructure levels, the game user may examine the trade-offs among planning goals and among possible avenues of investment or other management interventions. A study of the environmental cost of producing increasing amounts of food for a growing population in the Jalapa region illustrates the game's usefulness, and actual land allocations in the Jalapa region are compared with optimal allocations under different priorities. The carrying capacity of the region is examined from this point of view, giving particular attention to the demands that increasingly urban habits of consumption may place on the land and to the role properly directed technology can play in increasing carrying capacity without causing environmental damage.

Overview: Land availability is a key consideration for evaluating the potential of biomass energy. This depends not only on how much land is physically suitable for growing the biomass crop, but also on the environmental implications of an energy farm and the extent to which land can be freed from competing uses. Energy planning should include inventories to realistically assess the amount of land potentially available for biomass production and the trade-offs involved in using such land for biomass farms.

Abstract: It was observed that a significant percentage of natural water samples in Hawaii will not support successful development of Aedes albopictus larvae. In some water samples this is because of the presence of the copepod Mesocyclops leuckarti pilosa, which feeds upon first instar larvae and is capable of eliminating them entirely. Aedes albopictus larvae can also fail to develop when specific phytoplankton such as the colonial green alga Kirchneriella irregularis are abundant in the water. Aedes albopictus larvae feed on Kirchneriella to the exclusion of nearly all other food when Kirchneriella is abundant, but the larvae appear to starve to death. Further study on the impacts of zooplankton and phytoplankton on mosquito larvae will lay a foundation for mosquito control through plankton management.

Abstract: The biomass of sediment organisms can be measured by allowing carbon tracer to distribute itself through sediment cores. Application of this method to sediment from Marion Lake, British Columbia, indicated that most of the sediment microorganisms were concentrated in the top 2 cm of sediment, where the total biomass of microorganisms was estimated to be 183 μg C/cm². The radiotracer estimate compared favorably with independent measurements based on ATP and direct microscopic counts of sediment microorganisms.

Overview: Chapter 1 provides an overview of the major agricultural systems in Southeast Asia—for example, rice paddies, shifting cultivation, homegardens, commercial temperate vegetables, and commercial tree plantations—relating their organization in space and time to the environmental and social conditions with which they are associated. Each of the agricultural systems described in Chapter 1 is common throughout Southeast Asia, but each takes on a diversity of forms in different parts of the region.

Most rural landscapes in Southeast Asia are a patchwork of several of these agricultural systems, and even a single agricultural household often earns its living by simultaneously employing several systems on different parcels of land or on the same land during different seasons. The character of these agricultural systems can vary enormously, from purely traditional to heavily influenced by Western technology.

Some systems, such as homegardens and other forms of mixed cropping, tend to be more traditional and therefore receive considerable attention throughout the book. The traditional component of other systems, such as commercial vegetable farming and commercial tree plantations—including rubber and oil palm—tends to be less significant, and those systems receive correspondingly less attention.

Overview: Chapter 2 sets the conceptual scene by outlining the human ecology perspective, which embraces not only the farm as a biophysical ecosystem but also the human social system that interacts with that ecosystem in many ways. On the one hand, a human ecology perspective is concerned with the structure and function of agricultural ecosystems—how the soil, water, crops, pests, and other biological and physical components interact to generate both desired and undesired outputs of goods and services.

On the other hand, it is concerned with how small-scale farmers interact with the agroecosystems on which they depend for a living and how the human social system shapes those interactions.

The framework in Chapter 2 is expressed in several ways throughout the rest of the book. Chapters 3 through 6 present detailed examples of traditional agriculture in the Philippines, Thailand, and Indonesia. Chapters 7 through 9 focus on aspects of the social system and how they interact with traditional agroecosystems, while Chapters 10 through 13 each focus on a single agroecosystem element from the perspective of its interactions with the rest of the agroecosystem and the social system.

Chapter 14 follows a single topic—nutrition—through the numerous points of interaction between the agroecosystem and social system.

Overview: Chapter 4 contrasts agriculture in two parts of Northern Thailand. The first is more traditional, in a mountainous area where the main cropping systems are upland rice and swidden agriculture. The second area is a large irrigated valley where conditions are generally favorable for agriculture and rice and other crops can be grown throughout most of the year.

The valley area is fully integrated with a market economy, has been thoroughly exposed to modern agricultural technology, and emphasizes temporal sequences of monocultures. Nonetheless, the area retains much of its traditional agriculture. Chapter 4 describes the interplay between traditional and modern agriculture.

Overview: Chapter 5 describes rainfed agriculture in Northeast Thailand, where soils are poor and rainfall is marginal and erratic. Traditional agriculture appears to have made the most of the available resources. Different cropping systems are adjusted to subtle differences in the land, and farm households coordinate their labor among those systems.

This chapter relates recent efforts by scientists to intensify agriculture in Northeast Thailand and the difficulties they have encountered in developing cropping systems that perform better than traditional ones.

Overview: Chapter 6 describes two highly sophisticated mixed-cropping systems that account for most food production in addition to rice in Java, where a high human population density forces farmers to extract their subsistence efficiently from a small amount of land. Perennial tree crops are an important part of both cropping systems. In the homegarden, trees are interplanted with field crops; in the other system, tree plantations are rotated with field crops to form a highly intensive “permanent swidden.”

Overview: The technology that forms the basis for structuring traditional agroecosystems is codified as knowledge passed from generation to generation. Chapter 9 explores the nature of this traditional knowledge within the science of “ethnoecology.” The chapter is concerned with how traditional farmers perceive the agroecosystems they manage and how those perceptions translate into their management practices.

Overview: Chapter 10 moves to the biophysical side of agroecosystem function by focusing on soil processes. It attempts to show how traditional agriculture has persisted on the same land for so long without the kind of soil degradation that creates dependence on fertilizer applications to maintain yields.

Traditional agriculture has employed a variety of strategies to maintain soil fertility, including using mulch and other crop residues to maintain soil organic matter, recycling mineral nutrients to maintain nutrient levels in the agroecosystem, and maintaining vegetative cover to prevent soil erosion. The mixed-cropping character of traditional agriculture, which plays a major role in all these functions, is examined in particular ecological depth.

Also important is the detailed knowledge traditional farmers possess about the capabilities of different kinds of land and their ability to match different cropping systems with different kinds of land.

Overview: Chapter 12 addresses the ways traditional farmers deal with weed and insect pests in their agroecosystems. Traditional agriculture is noteworthy in this respect because serious pest damage is unusual even though many kinds of pests are found in traditional fields and modern chemical pesticides are not employed.

What are traditional farmers doing right? The answer is complex, but it appears to lie in a combination of the pest resistance of local crop varieties, the interplanting of several crops in the same field, and the fact that traditional agricultural landscapes are usually a patchwork of different cropping systems.

Overview: Chapter 14 illustrates how detailed numerical data from a field study can be used to explore the interplay of ecological and social factors around a single agroecosystem topic: the integration of three agricultural systems in Java to provide a balanced diet. The chapter describes the impact of household economic status, land tenure, dietary preferences, and involvement in a cash economy on the cropping systems a household employs and the consequences for nutrition.

Of particular significance is crop diversity, which is highly developed in Javanese agriculture but may be eroded as agriculture modernizes.

Overview: Chapter 15 discusses the implications of recent agricultural development policies in Southeast Asia for agricultural research in general and human ecology research on traditional agriculture in particular. Any serious attempt to improve agriculture across Southeast Asia will require attention to local environmental and social conditions beyond the centralized agricultural research and development strategy that prevailed until recently.

Agricultural research may need to draw on the intellectual resources of small-scale farmers in several ways—not only by identifying traditional agricultural practices of particular value, but also by incorporating farmers as equal partners with scientists in the agricultural research process.

Overview: This article examines the potential use of mosquito-indigestible phytoplankton as a form of biological mosquito control. It describes green algae in the order Chlorococcales that mosquito larvae consume but cannot digest, causing the larvae to starve when these algae predominate in their food supply. The article discusses experiments aimed at replacing naturally occurring phytoplankton with locally adapted indigestible species and considers the use of filter-feeding zooplankton such as Daphnia to help establish and maintain them. It also examines potential ecological advantages of the approach, including compatibility with natural mosquito predators and the low likelihood that mosquitoes could evolve resistance. The article concludes by identifying important uncertainties and proposing further field studies to determine the mosquito species and breeding habitats for which this approach might be practical.

Overview: Most kinds of phytoplankton are good food for mosquito larvae. However, Culex, Aedes and Anopheles larvae fail to develop successfully in water where certain species of closely related green algae in the order Chlorococcales are the main source of food; apparently because the larvae are unable to digest them. Many species of Scenedesmus, Kirchneriella, Dactylococcus, Elakotothrix, Tetrallantos, Coelastrum, Selenastrum and Tetradesmus have this effect. These algae may offer a practical possibility for mosquito control when introduced into mosquito breeding habitats. Introduction of these algae could be assisted by simultaneous introduction of select filter-feeding zooplankton such as Daphnia.

Overview: This paper examines the potential use of mosquito-indigestible phytoplankton as a form of biological mosquito control. It describes observations and experiments showing that larvae of several mosquito genera can starve when their aquatic habitats are dominated by certain green algae that they consume but cannot digest. The paper identifies groups of algae with this property, discusses observations of their effects in natural and experimental habitats, and considers ecological conditions that might allow these algae to become established and predominate over digestible phytoplankton. It also examines the potential role of filter-feeding zooplankton in helping introduced algae become dominant. The paper discusses possible advantages and limitations of this approach and identifies further field experimentation needed to determine the mosquito species and breeding habitats for which phytoplankton management might be practical.

Abstract: Small-scale, subsistence agriculture in Java has an exceptional diversity of interplanted crops—a diversity that is declining as farm sizes decrease due to population growth and greater emphasis is placed on the most profitable crops for an expanding market economy. The nutritional consequences of these changes can be examined by examining interrelationships between household economic status, market involvement, dietary preferences, crops employed, crop yields and food consumption. The large quantity of rice in the Javanese diet frequently leads to deficiencies in the production and consumption of calcium, iron, riboflavin and vitamin A. Mixed-cropping fields and homegardens are the major source of these critical vitamins and minerals. The production of these vitamins and minerals is greater in fields and gardens with a greater diversity of interplanted crops. Some Javanese families do not have sufficient land to produce all the food they need. In addition to the vitamins and minerals mentioned above, calories and methionine are in particularly short supply for these families. Data obtained indicated that a mix of starchy root crops, legumes and green leafy vegetables can satisfy nutritional needs with the least amount of land. This is the cropping strategy generally followed by families with insufficient land, but they could improve their nutrition by placing greater emphasis on specific green leafy vegetables that produce larger quantities of critical vitamins and minerals. An increase in the market economy itself does not appear to have undesirable nutritional consequences, since families are not losing critical nutrients in the process of selling their produce and buying other foods for home consumption.

Overview: The Southeast Asian Universities Agroecosystem network (SUAN) has used five system properties to assess agroecosystem performance: productivity, stability, sustainability, equitability and autonomy. Assessing these properties can be useful for agricultural research and development, but the assessment is complicated by several factors. First is the multidimensional character of these properties, due to (a) independent measures of agricultural production and (b) differences in the same property at different hierarchical levels of an agroecosystem. Secondly, there are significant limitations in generalizing agroecosystem assessment from one set of environmental and social conditions to another. The SUAN network has examined trade-offs between these properties and implications of the trade-offs for agroecosystem design. Increases in productivity can be at the expense of other system properties, or they can be mutually reinforcing, depending on how the agroecosystem is organized.

Overview: This paper presents guidelines developed for comparative case studies of rural ecosystems in Southeast Asia, with the aim of providing researchers with a common conceptual and analytical framework. It defines a rural ecosystem as a human community together with the ecosystems with which it interacts and describes methods for identifying land-use systems, resource flows, inputs and outputs, and relationships among ecological and social components. The paper provides detailed approaches for assessing agroecosystem properties including productivity, stability, and sustainability, as well as social-system properties including autonomy, solidarity, and equitability. It also considers relationships and potential trade-offs among these properties and emphasizes comparison across case studies as a means of identifying broader patterns. The guidelines are intended both to organize existing empirical information and to reveal gaps, generate new research questions, and strengthen the analysis of human-environment interactions relevant to rural development.

Abstract: Eighteen species of cyclops were collected from a variety of aquatic habitats in New Orleans. Six of the species prey on first-instar Aedes albopictus larvae: Acanthocyclops vernalis, Diacyclops navus, Macrocyclops albidus, Mesocyclops edax, Mesocyclops longisetus, and Mesocyclops sp. (leuckarti group). They generally thrive when introduced to tires. Macrocyclops albidus and Mesocyclops sp. appear most promising for biological control because introduced populations of these two species usually kill all larvae that hatch into tires. Naturally occurring mixtures of D. navus and M. albidus in discarded tires were observed to reduce the number of Ae. albopictus larvae by 95 percent.

Abstract: Forty-two ground water sites on the Pacific and Atlantic coasts of Colombia were sampled quantitatively with a plankton net to assess the abundance of mosquito larvae and associated fauna. Many of the sites contained substantial numbers of Anopheles albimanus Wiedemann larvae, but the larvae were virtually absent wherever there were large populations of the copepods Mesocyclops venezolanus, M. longisetus, or M. aspericornis. Mesocyclops were observed to prey readily upon first-instar An. albimanus larvae in the laboratory, but smaller genera of cyclopoid copepods did not kill An. albimanus larvae. We conclude that Mesocyclops may prove useful for biological control of Anopheles.