Search

Resumo: Avaliou-se a composição químico-bromatológica de silagens de forrageiras lenhosas em delineamento experimental inteiramente casualizado com seis tratamentos e quatro repetições. Os tratamentos foram compostos pelas espécies forrageiras: Prosopis juliflora, Mimosa tenuiflora, Mimosa caesalpiniifolia, Gliricidia sepium e Leucaena leucocephala. Verificou-se que as silagens de jurema preta, jucá e sabiá, apresentaram altos teores de MS, acima de 35%. A silagem de leucena apresentou maior teor de PB (22,40%) e maior pH (5,5), enquanto que a silagem de algaroba apresentou o menor teor de EE (2,83%). A silagem de gliricídia resultou em maior teor de N-NH3 (10,93%) e de NDT (66,94%) e menor teor (3,79%) de lignina. A silagem de sabiá apresentou maior teor de FDN (64,09%), enquanto seu teor de FDA (35,54%) foi semelhante à da silagem de jurema preta (35,76%). As silagens de algaroba e gliricídia apresentaram os maiores teores de CNF (28,32 e 26,86%, respectivamente) e menores teores de hemicelulose (13,39 e 12,65%, respectivamente). As silagens de leucena e gliricídia apresentaram menores teores de celulose com 14,77% e 15,53%, respectivamente. As silagens das forrageiras lenhosas estudadas nesse trabalho apresentam boa qualidade e podem ser fontes de alimento animal. [Evaluation of the chemical composition of woody forage silages of the Brazilian semiarid]. Abstract: The aim of this work was to evaluate the chemical composition of the woody forage silage in the completely randomized design with six treatments and four replications. The treatments consisted of forage species: Prosopis juliflora, Mimosa tenuiflora, Mimosa caesalpiniifolia, Gliricidia sepium, Leucaena leucocephala and Caesalpinia ferrea. It was found that the silages jurema preta, jucá and sabiá, showed higher levels of DM more than 35 %. Leucena silage presented a higher content of CP (22.40 %) and higher pH (5.5), while the algaroba silage presented lowest level of EE (2.83 %). Higher levels of N-NH3 (10.93 %) and TDN (66.94 %) and lowest content of lignin (3.79 %) were found for gliricidia silage. Sabia silage presented a higher content of NDF (64.09%), while its ADF valor (35.54%) was similar to jurema preta silage (35.76 %). Algaroba and gliricidia silages presented highest levels of NFC (28.32 and 26.86%, respectively) and lower hemicellulose (13.39 and 12.65%, respectively). Leucena and gliricidia silages showed lower levels of cellulose with 14.77 and 15.53%, respectively. The woody forage silages studied in this work shown a good quality and can be used as sources in animal feed.

Assessment of the content and sources of heavy metals in soils is required to identify agricultural areas affected by contamination on a regional level, according to the European Thematic Strategy for Soil Protection. The total content of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn of 29 agricultural soils used to grow vegetable crops such as artichoke, broccoli, and potato, in the Segura River Valley, Alicante, Spain, as a representative area of the semiarid Mediterranean region, was determined to assess the current state of heavy metal contamination of agricultural soils. The mean values (mg kg-1) were: Cd, 0.38; Co, 7.9; Cr, 28.3; Cu, 21.6; Fe, 15,274; Mn, 320; Ni, 23.7; Pb, 19.6; and Zn, 57.8. These values followed the sequence: Fe>Mn>Zn>Cr>Ni>Cu>Pb>Co>Cd. Despite intensive production, the soil heavy metal concentrations were equal to, or lower than concentrations determined by others working on Spanish agricultural soils. Nevertheless, some plots had high Cd and Pb concentrations. Based on these results and others from the Spanish Mediterranean region, further studies under semiarid conditions are required to obtain a better knowledge of the pollution levels, especially in the case of anthropogenic metals such as Cd and Pb. This is critical to safeguard the environmental and production functions of these soils and, therefore, their quality. Further, given the importance of vegetables in the Mediterranean diet, it is important to extend the work to other areas of the European Mediterranean region., La evaluación del contenido y origen de los metales pesados en suelos a escala regional es relevante para la identificación de zonas agrícolas afectadas por contaminación, de acuerdo con la Estrategia Temática Europea para la Protección del Suelo. Los contenidos totales de Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb y Zn en 29 suelos agrícolas dedicados a cultivos vegetales (ej. alcachofa, bróculi, patata) de la comarca del Bajo Segura (Alicante, España), área representativa del ámbito mediterráneo semiárido, fueron analizados con el objeto de evaluar el estado actual de estos suelos agrícolas, en referencia a procesos de contaminación por metales pesados. Los valores medios fueron (en mg kg-1): Cd 0,38; Co 7,9; Cr 28,3; Cu 21,6; Fe 15.274; Mn 320; Ni 23,7; Pb 19,6; y Zn 57,8. Estos valores medios siguieron la siguiente secuencia: Fe>Mn>Zn>Cr>Ni>Cu>Pb>Co>Cd. A pesar de las prácticas agrícolas intensivas en estos suelos, los contenidos de metales pesados fueron iguales o incluso menores a las concentraciones analizadas por otros autores en suelos agrícolas españoles. No obstante, algunas parcelas presentaron mayores concentraciones de Cd y Pb, desde un punto de vista comparativo. Teniendo en cuenta estos resultados y otros alcanzados en la región mediterránea española, se requieren mayores estudios en condiciones semiáridas para obtener un mejor conocimiento sobre los niveles de contaminación, especialmente en el caso de metales de origen antrópico como el Cd y Pb. Esto resulta crítico para preservar las funciones productivas y ambientales de estos suelos y, por tanto, su calidad. Además, dada la importancia de los cultivos vegetales en la dieta mediterránea, sería relevante extender esta investigación a otras zonas semiáridas de la región mediterránea europea.

Metadata only record In order to lower salinity levels in Australia's Mullay-Darling watershed, a pilot study using water transpiration credits is being tried to increase forest cover. A company, State Forests, is managing 2 million hectares of public native forests along with increasing amounts of planted forests. Local irrigation farmers have entered into an agreement with State Forests to support tree planting in turn for salinity credits. The goal is large scale reforestation, 40% reforestation is the goal to reverse the current salinity problem. PES-1 (Payments for Environmental Services Associate Award)

Many soils in the Mediterranean region are subjected to progressive degradation as a result of water erosion. A study was carried out to examine the effects of biosolids on a degraded soil. Single doses of 40, 80 and 120 Mg haE–1 of a biosolid were applied to the surface of soil and their effects on its chemical characteristics and on the native vegetation were assessed. Soil macronutrients, micronutrients and heavy metals were tested one and five years after application. Canopy cover, biomass production and mineral composition of native vegetation were also determined. Biosolids increased the content of most nutrients in the soil, although this effect decreased over time. The soil organic matter content did not increase significantly at the beginning of the experiment, although significant differences were observed after five years. The contents of total and extractable heavy metals did not change with time after the application. The native plant biomass production and the canopy cover significantly increased with all the doses applied at the beginning of the experiment, and remained high five years after biosolids application., Se ha realizado una experiencia de restauración de un suelo degradado en un ecosistema semiárido. Diferentes dosis de biosólidos (40, 80 y 120 Mg haE–1) fueron aplicados una única vez en superficie y se estudiaron sus efectos sobre las principales propiedades químicas del suelo y la cobertura vegetal, producción de biomasa y composición mineral de la vegetación nativa al año y a los cinco años de la aplicación. Las dosis de biosólido incrementaron los contenidos de nutrientes en el suelo, aunque su efecto disminuyó con el tiempo. El contenido de materia orgánica del suelo no experimentó cambio al comienzo de la experiencia, mientras que hubo diferencias significativas entre tratamientos en el último año. El contenido de metales pesados del suelo no varió a lo largo del estudio. La producción de biomasa y cobertura vegetal se incrementaron significativamente con todas las dosis ensayadas y permanecieron así a lo largo de los cinco años del estudio.

Most rangelands are managed inappropriately in Argentina. This article provides some simple guidelines that can ensure a better grazing of rangeland vegetation and simultaneously increase beef production. Our main objective was to prove that a few simple management guidelines and a short-duration, high-intensity grazing system would increase beef production per acre, while at the same time maintaining the forage resource in the community. Studies were conducted in the phytogeographical province of the Monte1 (Fig. 1, 40°39′S, 62°54′W) in central Argentina. Average annual temperature is 54° to 57°F and rainfall is scanty with 8 to 12 inches annually concentrated in winter and spring; average annual evapotranspiration is about 31 inches per year. This is an extensive, almost continuous, and rather uniform area of shrublands. Fil: Giorgetti, Hugo Dosindo. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; Argentina Fil: Busso, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina Fil: Montenegro, Oscar Alberto. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; Argentina Fil: Rodriguez, Gustavo Dionisio. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; Argentina Fil: Kugler, Nora M.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria Alto Valle; Argentina

Many soils in the Mediterranean region are subjected to progressive degradation as a result of water erosion. A study was carried out to examine the effects of biosolids on a degraded soil. Single doses of 40, 80 and 120 Mg haE–1 of a biosolid were applied to the surface of soil and their effects on its chemical characteristics and on the native vegetation were assessed. Soil macronutrients, micronutrients and heavy metals were tested one and five years after application. Canopy cover, biomass production and mineral composition of native vegetation were also determined. Biosolids increased the content of most nutrients in the soil, although this effect decreased over time. The soil organic matter content did not increase significantly at the beginning of the experiment, although significant differences were observed after five years. The contents of total and extractable heavy metals did not change with time after the application. The native plant biomass production and the canopy cover significantly increased with all the doses applied at the beginning of the experiment, and remained high five years after biosolids application. Se ha realizado una experiencia de restauración de un suelo degradado en un ecosistema semiárido. Diferentes dosis de biosólidos (40, 80 y 120 Mg haE–1) fueron aplicados una única vez en superficie y se estudiaron sus efectos sobre las principales propiedades químicas del suelo y la cobertura vegetal, producción de biomasa y composición mineral de la vegetación nativa al año y a los cinco años de la aplicación. Las dosis de biosólido incrementaron los contenidos de nutrientes en el suelo, aunque su efecto disminuyó con el tiempo. El contenido de materia orgánica del suelo no experimentó cambio al comienzo de la experiencia, mientras que hubo diferencias significativas entre tratamientos en el último año. El contenido de metales pesados del suelo no varió a lo largo del estudio. La producción de biomasa y cobertura vegetal se incrementaron significativamente con todas las dosis ensayadas y permanecieron así a lo largo de los cinco años del estudio.

The Southern African Millennium Ecosystem Assessment (SA f MA) evaluated the relationships between ecosystem services and human well-being at multiple scales, ranging from local through to sub-continental. Trends in ecosystem services (fresh water, food, fuel-wood, cultural and biodiversity) over the period 1990–2000 were mixed across scales. Freshwater resources appear strained across the continent with large numbers of people not securing adequate supplies, especially of good quality water. This translates to high infant mortality patterns across the region. In some areas, the use of water resources for irrigated agriculture and urban–industrial expansion is taking place at considerable cost to the quality and quantity of freshwater available to ecosystems and for domestic use. Staple cereal production across the region has increased but was outstripped by population growth while protein malnutrition is on the rise. The much-anticipated wood-fuel crisis on the subcontinent has not materialized but some areas are experiencing shortages while numerous others remain vulnerable. Cultural benefits of biodiversity are considerable, though hard to quantify or track over time. Biodiversity resources remain at reasonable levels, but are declining faster than reflected in species extinction rates and appear highly sensitive to land-use decisions. The SA f MA sub-global assessment provided an opportunity to experiment with innovative ways to assess ecosystem services including the use of supply–demand surfaces, service sources and sink areas, priority areas for service provision, service ‘hotspots’ and trade-off assessments.

PES-1 (Payments for Environmental Services Associate Award)

Metadata only record This paper addresses the need for development and research to be invested in semiarid regions of sub-Saharan Africa - not just in the high rainfall and irrigated regions, which have been the focus of efforts in the last three decades. The authors also describe the negative impact of the lack of policy regarding profitability of food crops. Good weather causes price collapse and bad weather creates crises that require food aid or subsidized food imports. The authors suggest the need for demand-side dissemination of improved technologies. To evaluate the effect of technological change and demand shifts for sorghum, the authors apply a sector model. The model simulates the impacts of policy combinations that cause farmers to receive higher prices after adopting higher-input technologies. The model also compares a policy focused on increasing yield and demand for sorghum in the semiarid region to policy strategies for high-rainfall zones.

In semi-arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop productivity. The aim of this study was to analyse agricultural drought, and to evaluate soil and water management options and strategies for sustainable crop production in drought-prone semi-arid Kenya. Research was conducted at an experimental site in Katumani and in Iiuni watershed, both in Machakos district. First the occurrence of dry and wet spells in Iiuni was modelled using a Markov model. The study revealed that the short rains (October-December) are more reliable for crop production than the long rains (March-May). A literature review on tillage methods for soil and water conservation in eastern Africa showed the importance of appropriate tillage practices and the benefits of residue management for improved soil moisture conditions. Especially conservation tillage techniques were found to be promising for the improvement of crop productivity under semi-arid climatic conditions. Moreover, farm yard manure application in combination with tillage appeared effective in reducing surface runoff from a crusting and compacting soil, especially during the early stages of the rainy season. At the watershed scale, the AGNPS model was applied to evaluate the effect of land use changes on watershed runoff volume. Changes in land use covering a period of nearly 20 years were significant, with an dramatic increase in the area for crop cultivation, but this did not have a significant effect on the hydrology. The reason is the widespread adoption of soil and water conservation measures (mainly bench terracing) that occurred during the same period. The last part of the thesis deals with suitable options for watershed conservation in semi-arid Kenya. Apart from technical solutions, the enabling conditions to farmers at various hierarchical policy levels are discussed. A few of these enabling conditions that are elaborated upon include agricultural policy, focus on smallholder agriculture and public-community partnerships

This paper provides perspectives on the value of participatory research in empowering rural communities in transition. It highlights one collaborative community-university research alliance in coastal British Columbia and illustrates the benefits and challenges of close linkages between social scientists and communities. It discusses how participatory research can build capacity for successful community economic and social transitions in rural British Columbia, and how challenges and key considerations of community- researcher partnerships are addressed.

Metadata only record A physically based catchment model (SWAT) was used for recharge estimation in the headwaters of the Liverpool Plains in NSW, Australia. The study used water balance modelling at the catchment scale to derive parameters for long-term recharge estimation. The derived parameters were further assessed at a subcatchment scale. Modelling results suggest that recharge occurs only in wet years, and is dominated by a few significant years or periods. The results were matched by independently observed bore data across the study area in the past 30 years. The study suggests that variations in recharge can be primarily explained by the climatic factor rather than land-use changes. The study estimated less recharge than previous studies where point scale modelling results have been scaled up to the catchment scale. It suggests that a catchment-based approach is needed for recharge estimation at the catchment scale. The study indicates that the current model may overestimate runoff on cracking vertosols under dry conditions where improvement is likely needed. The need for long-term runoff and bore monitoring data to confidently establish the relationships among water balance/recharge estimation and groundwater level variation is discussed. SWAT provides an alternative to point scale modelling for evaluating recharge and its response to changes in land use and land management.

Metadata only record In chapter 14, El Hadj et al. describe research in response to a request by Peul village women to deal with Cassia tora, an invasive plant that is unpalatable for grazing animals. As pasture lands have degraded, Cassia tora has spread throughout their fields out competing other plants. However, this noxious plant has potential as dry season forage when ensiled. The authors describe their analysis of the forage potential and their work with village women to develop ensilage techniques adapted to local conditions. ME (Management Entity)

Metadata only record In chapter 15, Abaye et al. investigated the regenerative potential of pastureland in two villages through a controlled experiment with tethered grazing of small ruminants. This work builds on the Holistic Management (chapter 9) insight that animal impact is not simply a function of numbers of livestock or duration of grazing time in order to provide management indicators that optimize the potential of forage regeneration/biomass production rates, plant biodiversity, and animal performance. The chapter concludes that grazing vegetation down to a 3cm height on any particular parcel is likely to limit forage regeneration. ME (Management Entity)

In semi-arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop productivity. The aim of this study was to analyse agricultural drought, and to evaluate soil and water management options and strategies for sustainable crop production in drought-prone semi-arid Kenya. Research was conducted at an experimental site in Katumani and in Iiuni watershed, both in Machakos district. First the occurrence of dry and wet spells in Iiuni was modelled using a Markov model. The study revealed that the short rains (October-December) are more reliable for crop production than the long rains (March-May). A literature review on tillage methods for soil and water conservation in eastern Africa showed the importance of appropriate tillage practices and the benefits of residue management for improved soil moisture conditions. Especially conservation tillage techniques were found to be promising for the improvement of crop productivity under semi-arid climatic conditions. Moreover, farm yard manure application in combination with tillage appeared effective in reducing surface runoff from a crusting and compacting soil, especially during the early stages of the rainy season. At the watershed scale, the AGNPS model was applied to evaluate the effect of land use changes on watershed runoff volume. Changes in land use covering a period of nearly 20 years were significant, with an dramatic increase in the area for crop cultivation, but this did not have a significant effect on the hydrology. The reason is the widespread adoption of soil and water conservation measures (mainly bench terracing) that occurred during the same period. The last part of the thesis deals with suitable options for watershed conservation in semi-arid Kenya. Apart from technical solutions, the enabling conditions to farmers at various hierarchical policy levels are discussed. A few of these enabling conditions that are elaborated upon include agricultural policy, focus on smallholder agriculture and public-community partnerships

Metadata only record In chapter 3, Badini and Dioni present a detailed description of the landscape types and soils of the Commune of Madiama. Combining knowledge gained from informal surveys, field observations, biophysical monitoring, transects, remote sensing, and pit holes, the chapter characterizes soil types and distributions, climate and hydrology, cropping patterns, land use systems and potentials. The database on these landscape types, their location, potentials and constraints is at an appropriate scale for use by village, commune and regional level planners, as well as for providing input to biophysical models to evaluate technologies (as in chapter 11). ME (Management Entity)

The range of natural variability (RNV) is a concept relevant to maintaining biodiversity and resilience in managed forests. It is, however, a challenging concept both to describe and apply. Here, we refine the definition of RNV. We also discuss information and data sources required and the appropriate use of spatial and temporal scales. A new term, the apparent range of variability (ARV), is suggested to convey the dependency of estimates of the RNV on the temporal and spatial extent of available data sources. We offer a process for developing an RNV definition, applying it operationally, and integrating desired future conditions with social and economic values. We illustrate the challenges in defining and implementing the RNV concept with an example of the Interior Douglas fir (IDF) (Pseudotsuga menziesii var. glauca) forests in Lignum Ltd.'s (now Riverside Forest Products Ltd.) Innovative Forest Practices Agreement area in central British Columbia, Canada. This paper outlines the rationale for using the RNV concept to guide forest management, defines RNV and methods used to estimate it, suggests a process to apply this concept to forest management in the IDF, and describes some of the challenges and limitations in using the RNV concept.

Determining the optimal sowing date is important when evaluating the production potential of any new crop. Field trials were performed with Amaranthus cruentus L., A. hypochondriacus L. and A. mantegazzianus Pass. from 1999 to 2002 in the semi-arid Argentine Pampa in order to establish the best sowing dates for grain production. Crops were sown at 15 day intervals during November, December and January. The following variables were then measured: plant height, days to anthesis, production of biomass, grain production, harvest index, final number of plants and plant losses. Rainfall strongly influenced these variables, depending on sowing date. In all years, A. mantegazzianus produced the lowest grain yields. The latest sowing date is not recommended since the light and temperature conditions during the final part of the phenological cycle have a negative effect on grain yield. The best results were obtained when sowing was performed from the second half of November through to the end of December., La fecha óptima de siembra es un dato esencial cuando se trata de evaluar el potencial de producción de un nuevo cultivo. A fin de establecer el rango óptimo de siembra para la producción de grano en la zona semiárida pampeana de Argentina, se realizaron entre los años 1999 y 2002 ensayos de campo con Amaranthus cruentus L., A. hypochondriacus L. y A. mantegazzianus Pass., probando fechas de siembra cada 15 días aproximadamente durante los meses de noviembre, diciembre y enero. Se midieron las siguientes variables: altura de planta, días a la antésis, producción de biomasa, producción de grano, índice de cosecha, población final de plantas y porcentaje de plantas perdidas. Las precipitaciones en cada año tuvieron incidencia para las variables analizadas, según la fecha de siembra. A. mantegazzianus tuvo menor rendimiento de grano que las otras dos especies en todos los años. La última fecha de siembra no resultó conveniente por la incidencia de las condiciones de luz y temperatura sobre el final del ciclo fenológico de las plantas, originando mermas en el rendimiento. Es por tanto recomendable sembrar entre la segunda quincena de noviembre y finales del mes de diciembre.

Metadata only record Effective communication is essential to the success of collaborative ecosystem management projects. In this paper, we investigated the dynamics of the Interior Columbia Basin Ecosystem Management Project's (ICBEMP) cross-disciplinary integration process in the assessment phase. Using a case study research design, we captured the rich trail of experience through conducting in-depth interviews and collecting information from internal and public documents, videos, and meetings related to the ICBEMP. Coding and analysis was facilitated by a qualitative analysis software, NVivo. Results include the range of internal perspectives on barriers and facilitators of cross-disciplinary integration in the Science Integration Team (SIT). These are arrayed in terms of discipline-based differences, organizational structures and activities, individual traits of scientists, and previous working relationships. The ICBEMP organization included a team of communication staffs (CT), and the data described the CT as a mixed group in terms of qualifications and educational backgrounds that played a major role in communication with actors external to the ICBEMP organization but a minor one in terms of internal communication, The data indicated that the CT-SIT communication was influenced by characteristics of actors and structures related to organizations and their cultures. We conclude that the ICBEMP members may not have had a sufficient level of shared understanding of central domains, such as the task at hand and ways and timing of information sharing. The paper concludes by suggesting that future ecosystem management assessment teams use qualified communications specialists to design and monitor the development of shared cognition among organization members in order to improve the effectiveness of communication and cross-disciplinary integration.

‘Let me assure you all that our commitment to the preservation of wildlife and the habitat in the Maasai Mara reserve is total. We do not deny that the reserve is of vital economic importance to us, but we also firmly believe, and proclaim, that wildlife deserves to be protected for its own sake. The animals are God's creatures and we affirm their right to live and survive as undisturbed as possible in this busy and over-populated world. The Mara can provide a relief from the commercial pressures of profit and survival. We must thus emphasize that in the Maasai Mara reserve interests of wildlife are paramount.' Samson Ole Tuya, Chairman Narok County Council — Maasai Mara Tourism Workshop, March 1991 ‘The chances of wildlife surviving when people are hungry and poor are becoming increasingly slim.' Samson Ole Tuya, Member of Parliament, Narok South. Workshop — Defining the framework for management and conservation planning for the Maasai Mara ecosystem, November 1996 The Maasai Mara ecosystem has one of the richest assemblages of wildlife in the world and supports about 237 herbivores per km2, making it one of the most productive natural terrestrial ecosystems. It maintains the greatest and most spectacular large mammal migration on earth and is the most highly visited tourist area in the East African region. Tourism generates millions of dollars annually while livestock and agriculture contribute significantly to the local and national economy. This paper examines the enormous threats facing the ecosystem and the efforts being made to keep the ecosystem open in order to support a vibrant tourist trade and a healthy livestock economy. These aspects are currently threatened by a burgeoning human population, land subdivision, changing land tenure systems, crop farming, poaching, habitat fragmentation, blockage of wildlife migratory corridors, habitat destruction, sedentarisation, environmental degradation and poverty. Wildlife conservation is in conflict with agriculture, while tourism has taken away the best grazing areas for livestock. The paper also reviews the ecological and socio-economic problems associated with tourism, land use changes and break down of traditional governance structures and how they have weakened the capacity of Maasai Mara to sustain a viable wildlife populations. Keywords: human impacts, land use, livestock, social conflict, traditional values African Journal of Range & Forage Science 2004, 21(2): 79–88

The scientific and conceptual contributions Jim Ellis made throughout the course of his career reveal a logical progression towards increased understanding of pastoral ecosystems worldwide. Research in wildlife, large herbivores, systems ecology and energy flows through grazing ecosystems formed the basis of his approach. A leader of the South Turkana Ecosystem Project (STEP), he showed the adaptive basis for opportunistic and spatially extensive resource use in temporally and spatially variable environments. After the STEP, he examined pastoral ecosystems in northern and central Asia and elsewhere in Africa. Spatial extensivity, or scale, emerged as being critically important to pastoral ecosystem function. Livestock development schemes based upon inappropriate ecological and economic assumptions are all too often ecologically and economically unsustainable. However, a new paradigm of pastoral ecology and development is emerging. The paradigm is derived from basic, but comprehensive, understanding of the ecologically adaptive features of pastoral resource utilisation strategies, and the ecological processes and constraints that determine energy flows from plants to livestock and humans in spatially and temporally variable environments. Jim Ellis contributed greatly to improved understanding of the importance of mobility and opportunism in these ecosystems. This understanding could benefit humans, ecosystems and wildlife over a vast portion of the earth's surface. Keywords: development, ecosystems, livestock, pastoralism, spatial scale African Journal of Range & Forage Science 2004, 21(3): 191–200

This study compares the vegetative growth and productive parameters of non-irrigated Monastrell vines with those under two moderate irrigation treatments. Plant water status and gas exchange parameters were used to evaluate the effect of moderate irrigation on the physiological status of the plants. The predawn and midday leaf water potentials were significantly lower in non irrigated vines, reaching values that indicated severe water stress. Stomatic conductance decreased as the season progressed, especially in non-irrigated vines. This stomata closure resulted in lower net photosynthesis, which affected vegetative growth and productivity. Non-irrigated vines developed a very small canopy and pruning weight together with a very low production compared with irrigated vines. The results demonstrate that the improvement in the physiological status of plants, with moderate irrigation leads to higher yield together with an equilibrium in the vegetative/reproductive growth. Este estudio compara el crecimiento vegetativo y los parámetros productivos de vides Monastrell en secano y otras con dos tratamiento de riego. Para evaluar el efecto del riego en la planta, se midieron los potenciales hídricos al alba y al mediodía y los parámetros de intercambio gaseoso. Los potenciales hídricos fueron significativamente menores en plantas en secano, alcanzando valores que indican un fuerte estrés hídrico. La conductancia estomática decreció al avanzar la estación, especialmente en viñas en secano. El cierre estomático se tradujo en una fotosíntesis neta menor, lo que afectó al desarrollo vegetativo y al rendimiento. Las viñas en secano desarrollaron una masa foliar muy pequeña y un peso de poda muy bajo. Los resultados demuestran que la mejora del estado hídrico de las plantas condujo a producciones mayores y a un correcto balance entre el desarrollo vegetativo y productivo.

The principal objectives of this study were to chronicle the hybrid approach to data collection adopted to formulate a regional economic overview of the Robson Valley Forest District (RVFD), British Columbia, Canada, and to summarize a suite of baseline economic indicators relevant to the forestry, visitor, public, and agriculture sectors in the RVFD region. Secondary data collection was augmented with primary data collected through formal and informal survey techniques. Data were collected for traditional economic indicators, such as gross revenue, employment, and income. The forestry sector is the largest contributor to the regional economy. It provides the highest estimates of average annual wage (ranging from 46 975 to $64 007), number of employment positions (574 jobs including full-time and part-time or seasonal positions), and total revenue ($74.1 million). The visitor sector, the second largest contributor, generates $18.1 million in revenues and 514 employment positions; however, the estimated average annual wage ($20 956) is the second lowest. The average annual wage in the public sector is the second highest at $25 669, with 350 employment positions existing in this sector. The agriculture sector is the smallest contributor, providing the lowest average annual wage ($19 145, or $17 420 inflated to 2001 dollars) and total revenue ($4.6 million). Despite the relatively lower contribution to the economy, the total number of farms has remained relatively stable. A comprehensive understanding of the mechanics of an economy facilitates decision making. This report provides a methodology for small region data collection and the resulting baseline information necessary for future assessment of responses within the economy to internal and external changes.

The Caribbean Sea and its watersheds show signs of environmental degradation. These fragile coastal ecosystems are susceptible to environmental impacts, in part because of their oligotrophic conditions and their critical support of economic development. Tourism is one of the major sources of income in the Caribbean, making the region one of the most ecotourism dependent in the world. Yet there are few explicit, long-term, comprehensive studies describing the structure and function of Caribbean ecosystems. We propose a conceptual framework using the environmental signature hypothesis of tropical coastal settings to develop a series of research questions for the reef-sea-grass-wetland seascape. We applied this approach across 13 sites throughout the region, including ecosystems in a variety of coastal settings with different vulnerabilities to environmental impacts. This approach follows the strategy developed by the Long Term Ecological Research program of the National Science Foundation to establish ecological research questions best studied over decades and large spatial areas.

Estimating the rate of soil carbon sequestration in degraded semiarid agroecosystems is of great interest due to the beneficial effects on soil properties, soil fertility, and the potential atmospheric CO2 mitigation. One of several applied methodologies, biogeochemical modeling, offers possibilities to distribute estimates of soil organic carbon (SOC) over regions, estimate the effects of changes in climate and ecosystem management on SOC, and quantify changes of soil properties over time or space. In this study, the sensitivity of the Century model was assessed in regards to uncertainties for soil texture, natural fire return periods, grazing intensities, and climate. The study area was situated in central Sudan and dominated by subsistence agroecosystems. Uncertainties in the modeling of historical SOC levels, prior to known human interactions, can be reflected in the estimation of the current or future SOC levels, as some soil processes take many years to occur. The relationship between these differences in historical and current SOC levels was calculated. Soil texture, derived from a number of different sources, had the greatest impact on modeled SOC. Overall, data uncertainties for the five parameters tested resulted in SOC variations of up to 160 g C/m2 (1.6 t C/ha) for the estimation of the current level (year 2002), which corresponds to a difference of approximately 80% of the average current level.

Determining the optimal sowing date is important when evaluating the production potential of any new crop. Field trials were performed with Amaranthus cruentus L., A. hypochondriacus L. and A. mantegazzianus Pass. from 1999 to 2002 in the semi-arid Argentine Pampa in order to establish the best sowing dates for grain production. Crops were sown at 15 day intervals during November, December and January. The following variables were then measured: plant height, days to anthesis, production of biomass, grain production, harvest index, final number of plants and plant losses. Rainfall strongly influenced these variables, depending on sowing date. In all years, A. mantegazzianus produced the lowest grain yields. The latest sowing date is not recommended since the light and temperature conditions during the final part of the phenological cycle have a negative effect on grain yield. The best results were obtained when sowing was performed from the second half of November through to the end of December. La fecha óptima de siembra es un dato esencial cuando se trata de evaluar el potencial de producción de un nuevo cultivo. A fin de establecer el rango óptimo de siembra para la producción de grano en la zona semiárida pampeana de Argentina, se realizaron entre los años 1999 y 2002 ensayos de campo con Amaranthus cruentus L., A. hypochondriacus L. y A. mantegazzianus Pass., probando fechas de siembra cada 15 días aproximadamente durante los meses de noviembre, diciembre y enero. Se midieron las siguientes variables: altura de planta, días a la antésis, producción de biomasa, producción de grano, índice de cosecha, población final de plantas y porcentaje de plantas perdidas. Las precipitaciones en cada año tuvieron incidencia para las variables analizadas, según la fecha de siembra. A. mantegazzianus tuvo menor rendimiento de grano que las otras dos especies en todos los años. La última fecha de siembra no resultó conveniente por la incidencia de las condiciones de luz y temperatura sobre el final del ciclo fenológico de las plantas, originando mermas en el rendimiento. Es por tanto recomendable sembrar entre la segunda quincena de noviembre y finales del mes de diciembre.

Ecosystem management is an approach to natural resource planning that theoretically places environmental issues on an equal footing with the economic concerns that dominate resource use. This approach recognizes the importance of both a healthy environment and access to natural resources. Each of these factors is an implicit element of human security, a political concept that promotes the protection of human lives and livelihoods. Ecosystem management acknowledges the role of humans as an integral part of the ecosystem; however, it does not define the ways in which humans and the ecosystem interact. This lack of definition makes the practical application of ecosystem management difficult. In this paper, we examine the application of ecosystem management principles in Clayoquot Sound, British Columbia, Canada. We propose that human security can act as an imperative for the expanded consideration of social networks and environmental pathways in the practice of ecosystem management. Theories from the social and natural sciences are supplied to support the science-based application of ecosystem management. These underpinnings enable managers to better define ecosystem boundaries and to integrate expanded social networks into management plans.

Ecosystem-based natural resource management involves the integration of biophysical and human dimensions. Both the social sciences and biophysical sciences contribute to our understanding of the process of balancing social, economic, and biological factors. While the role of the biophysical sciences is relatively well recognized in the natural resource management sector, the contributions of the social sciences are less well understood and they are less frequently incorporated into management plans and activities. In this paper, we summarize several distinct contributions of the social sciences to natural resource management in British Columbia, Canada, and describe 10 ways that decision makers use social sciences. We predict the role of social sciences in natural resource management will become more important and we suggest that more collaborative research projects between social science researchers and natural resource managers will emerge. We also suggest that more cross-fertilization within the diverse streams of social sciences - as well as between the social sciences and biophysical sciences - will be essential in order to address complex research questions related to natural resource management.

During a time when British Columbia's forest policy is undergoing unprecedented change, a lack of clarity surrounds what is desired for the forest industry and how future forests will be managed. This paper focuses on desirable changes to forest management to achieve sustainability. The author comments on current forest industry structure and recommends adoption of the Chief Forester's vision of the industry as “... the best managers of naturally forested landscapes in the world.” A set of goals to achieve this vision is outlined and a forest management framework is proposed that includes strategic direction, management instruments, and a system to implement the strategy. A draft “Sustainable Forest Management Contract” is presented for discussion. This instrument could address the limitations associated with current area- and volume-based tenure requirements and provide companies with a stake in long-term forest management.

With initiatives such as forest certification, innovative forest practices agreements, model forests, and community forest pilots, gathering data on social and economic factors relating to natural resource management is likely to be a growing area of social science research in British Columbia. This paper examines expert-driven versus community-driven participatory approaches to social science research. A hypothetical continuum of community involvement and power in the research process is presented that helps to distinguish between these research approaches. Arnstein's ladder of citizen participation also provides a useful guide to discussions about the desired level of community involvement in research. The challenges posed by increasing citizen participation in community research are examined, as is the potential of community-driven methods of social science research in British Columbia.

Designing policies for long-term forest management is difficult, in part because ecological processes that drive forest structure and composition interact strongly, both spatially and temporally, with the many values we want to obtain from the forest. Using the Robson Valley in east-central British Columbia (Canada) as a study area, we developed a spatio-temporal landscape model to assess the effects of uncertainties about stand-replacing natural disturbance regimes on indicators related to the sustainability of forest harvesting and biodiversity. Results show that key timber policy indicators were relatively less sensitive to natural disturbance regime parameters than were the biodiversity indicators of seral stage distribution and tree species composition. The other biodiversity indicator we examined, structural connectivity among old-forest patches, was among those indicators least sensitive to any of the parameters we studied. Other timber supply indicators including non-recoverable losses and volumes and areas disturbed were the most sensitive to both the particular natural disturbance agent chosen and to the parameters describing its behaviour. Projections of a range of scenarios for present and alternative natural disturbance and management regimes for the study area show that most indicators varied from less than 1 up to 93% from the value of the present management/disturbance regime. Generally, three alternative management policies had weak-to-moderate capabilities of reducing effects of natural disturbances. Despite the range of uncertainties explored, the results provided little indication that at the scale of the whole study area, current timber harvesting targets are not sustainable over the long term. However, our findings highlight the lack of knowledge about the future, particularly about changes in climate, resulting in significant uncertainty about the future condition of the forest and about future forest management opportunities.

This paper outlines a method of developing indicators of well-being in small, forest-based communities. It also describes some specific measures of well-being in a particular forest-based community in the Robson Valley Forest District, British Columbia, Canada. In this project, we attempted to strike a balance between relying on locally obtained information - collected through workshops, interviews, and a mail survey - and information obtained from the social science literature. We took a broad-based approach toward indicator development by identifying goals and indicators pertaining to the entire region. Our paper explores this theoretical orientation in some detail and then provides an account of the dialogical methods used to identify community-based indicators. Of the six community goals we identified, we discuss 'maintaining community capacity' at length by examining the empirical data from five indicators and then drawing some conclusions about the status of community capacity in the Robson Valley.

Generally, studies on biodiversity conservation have focused on topics within the natural sciences, such as species and ecosystem concerns. However, an understanding of the human dimensions of biodiversity conservation is lacking. To address this gap, a study was undertaken in the Robson Valley in east-central British Columbia, Canada, in 2001 to document stakeholders' understanding and perceptions of biodiversity issues, examine potential trade-offs associated with conservation, and provide decision makers with insight concerning the acceptability of potential forest management scenarios. A mail survey was used to collect data from residents of British Columbia and two groups of recreationists. Results show that stakeholders are diverse in their perceptions and knowledge related to biodiversity conservation. A choice experiment was used to examine trade-offs inherent in conserving biodiversity at the landscape level. The choice model showed that respondents preferred options that emphasized biodiversity conservation, and that Robson Valley residents had different preferences than the respondents in the other subsamples. Several potential forest management scenarios were simulated using the choice model results. The potential for future research, and ideas for improving the model, are discussed.

Forest planners in British Columbia (Canada) are required to identify forests suitable for designation as Old-Growth Management Areas. However, the tools currently in use lack the ability to identify appropriate stands. In 2000, we examined the ecological attributes of older forest in the Robson Valley Forest District in east-central British Columbia. The purpose was to determine the old-growth habitat value of stands of different age classes and to develop field procedures for assessing the relative old-growth quality of stands. We examined the relationships between stand age (both photo-interpreted and field-estimated) and attributes normally associated with old forest; in particular, we evaluated the relationship between stand age and functionally important tree and coarse woody debris configurations. Results from a representative portion of our study identified several attributes that were generally more abundant in older stands. The results also demonstrated that stands less than 140 years old have poorly developed old-forest habitat attributes, whereas these attributes are consistently well developed in stands greater than 140 years old. Also, the significance of these same attributes increases only slightly with increasing stand age. We created a rank scoring system to help forestry practitioners assess old-forest stands, particularly in the Interior Cedar-Hemlock biogeoclimatic zone, in terms of their value as old-growth wildlife habitat.

An analysis of pastorlist systems and recommendation for improved practices

A study was made of two savannah-like (dehesa) pastures on which cattle (Morucha cows × Charolais bulls) are raised for beef. The soil of dehesa system A was developed over slate, while that of B was developed over granite. The type of vegetation, dry matter yield (DM), raw protein (RP) content, digestible organic matter (DOM) content and the metabolizable energy (ME) of each system was determined to provide the nutritive value of the two types of pasture. Dietary supplements were assessed in the same way. The DM yields for 1989, 1990 and 1991 were 751, 1900 and 1438 for system A, and 577, 1937 and 1361 kg ha-1 for system B. The RP values for April and December were 17.6 +/- 1.4%, falling to a minimum of 6.7 +/- 0.4% in July-October. Intermediate values were seen for the rest of the year. The ME showed mean values of 9.4 +/- 0.3 and 7.9 +/- 0.2 MJ kg DM-1 for systems A and B respectively, while mean metabolicity was 0.50 +/- 0.2 and 0.44 +/- 0.1 (P < 0.05) and the DOM was 67.5 +/- 4.2% and 44.3 +/- 3.9% respectively. These values were affected by the year and harvest date (P < 0.05) and were always greater (P < 0.05) on soils developed over slates. The greatest pasture ME was achieved in spring and represented some 77-95% of total pasture production, depending on the year. Supplements represented approximately 20% of the total available ME., Se caracterizaron dos sistemas adehesados de pasto sobre suelos formados por la descomposición de pizarras (sistema A) y granitos (sistema B), dedicados a la producción de carne en extensivo, con vacas de raza morucha cruzadas con toro charolés. Se estimó el valor nutritivo de los pastos y de la alimentación suplementaria a partir del tipo de vegetación y producción de materia seca, proteína bruta, materia orgánica digestible y energía metabolizable. La producción en los años 1989, 1990 y 1991 fue, respectivamente, de 751, 1900, y 1438 kg DM ha-1 en pizarras, y 577, 1937 y 1361 kg DM ha-1 en granitos. En ambos sistemas, la media de proteína bruta alcanzó valores máximos de 17,6 +/- 1,4% en los meses de abril y diciembre, y mínimos de 6,7 +/- 0,4% en el periodo de julio a octubre; el resto del año valores intermedios. La materia orgánica digestible presentó contenidos medios de 67,5 +/- 4,2% y de 44,3 +/- 3,9%; la energía metabolizable, valores medios de 9,4 +/- 0,3 y 7,9 +/- 0,2 MJ kg DM-1, y metabolicidad media de 0,50 +/- 0,2 y 0,44 +/- 0,1. Estos contenidos fueron mayores (P < 0,05) en el suelo de pizarras, y en ambos suelos estuvieron influenciados por el año y la fecha de corte (P < 0,05). La oferta de energía metabolizable de primavera fue 77-95% de la producción total del sistema, y la suplementación energética el 20% de ésta, valor que confirma el carácter extensivo de estas explotaciones.

Range condition is usually estimated from the palatability and ecological attributes of rangeland species. The aim of this research was to assess whether the inclusion of nutritional parameters improves the estimation of range condition in the semiarid Prosopis caldenia Burk rangeland of La Pampa, Argentina. Plots (24 ha) containing rangeland in different condition (fair and good) were grazed at low stocking rates during fall, winter and spring of two successive years. The aerial biomass (kg DM ha-1), in vitro dry matter digestibility (IVDMD) and crude protein content (% CP) of monthly samples of each species were determined. The percentage of total biomass (% TB) and % CP were estimated for each of six IVDMD ranks. In both years, and across nearly all IVDMD ranks, the % TB was different (p < 0.05) for the two range conditions, though % CP was similar (p > 0.05). The carrying capacity of good rangeland was 2.5 times greater than that of fair one when total aerial biomass and expected animal performance were similar. Taking nutritional parameters into account improves estimates of range condition in P. caldenia rangeland., La condición del pastizal es habitualmente estimada en función de especies clasificadas por selectividad animal y atributos ecológicos. El objetivo de este trabajo fue evaluar si la inclusión de parámetros nutricionales mejora la estimación de la condición para la utilización ganadera de un pastizal semiárido de un bosque de Prosopis caldenia Burk. situado en La Pampa. Dos parcelas de 24 ha para cada condición contrastante (regular y buena) fueron pastoreadas a baja carga durante el otoño, el invierno y la primavera de dos años consecutivos, registrándose mensualmente la biomasa aérea (kg DM ha-1), la digestibilidad in vitro de la materia seca (DIVMS) y el contenido de proteína bruta (% PB) de cada especie. A partir de la DIVMS y biomasa de cada especie, se calculó la proporción de la biomasa aérea total (% BT) en seis rangos de DIVMS, y en cada uno de ellos se calculó el % PB. Durante ambos años y en casi todos los rangos de DIVMS, el % BT fue diferente (p < 0,05) entre condiciones, mientras que el % PB de la biomasa en cada uno de ellos fue similar (p > 0,05). Estos resultados permitieron inferir que, aunque la biomasa total absoluta fue similar entre condiciones, la condición buena ofreció 2,5 veces más biomasa para categorías de animales que requieren DIVMS igual o superior al 40%. La inclusión de parámetros nutricionales mejoró la estimación de la condición de estos pastizales para fines ganaderos.