Progress 07/01/97 to 12/31/03
Outputs
Our goal was to investigate options for rehabilitating the productivity of abandoned pasturelands and to quantify the effect of improved soil and plant management on above and belowground C and nutrient stocks and soil water dynamics. Two major pathways to rehabilitate the productivity of abandoned pastureland were studied. The first involved the addition of the major limiting nutrients in local soils, P and Ca, to accelerate growth of the secondary vegetation (SF). In the second, we quantified the carbon and nutrient stocks in 10-year-old agroforestry systems (AFS) relative to abandoned pasture vegetation to quantify the potential of managed agroforestry systems to rehabilitate the productivity of degraded pastures. The biomass-to-carbon conversion factor was higher for the trees in the AFS compared to the SF with means of .50 and .48, respectively. Nutrient stocks in AGBM were highest in the Palm System for N and Mg at 468.2 and 98.2 kg/ha respectively; in the Home
Garden for K at 407.6 kg ha-1 and in Secondary forest for P and Ca at 71 and 439 kg/ha respectively. As far as we know, these are the first estimates of C and nutrient stocks in agroforestry systems on degraded pasturelands in the Amazon and show higher C and nutrient accruel in AFS than SF. Forest soils store the highest amount of C (121 Mg/ha), followed by the AS2 system with 116Mg/ha. At the other extreme, soils under secondary vegetation presented the lowest stock (106Mg/ha). Results in this study indicate that agroforestry systems permit a moderate recovery of soil C stock relative to the control under secondary vegetation. Rates of C accrual are in the order of 1.8 Mg/ha/y. Biomass contributions in SF by diameter class are largely from the small diameter classes in the recently abandoned areas but shift to a moderately uniform distribution of biomass across all diameter classes in the oldest forests. Non-woody genera dominate the recently abandoned areas; shrubs less than 1 cm
DBH only contribute significant biomass in the 2 to 4 year-old forests before declining in importance. There is a 4.6 Mg/ha dry biomass increase with each 1 m2/ha tree basal area increment. Finally, small diameter stems are common throughout all of the forests, with more than 58 percent of the total stems in the 1 to 5 cm size class for all forests. This indicates ongoing seedling recruitment below the closing canopy, despite the declining stem density values in forests older than 6 to 8 years indicating otherwise. We developed a spatial simulation model of the dynamics of establishment of secondary forests in abandoned pastures for the Central Amazon. Our simulations show that low grazing results in rapid decline of NPP of Brachiaria, rapid weed invasion resulting in an acceleration of dominance by Vismia. With high grazing, weeds are never as dominant as in low grazing systems because more Brachiaria remains vigorous. With frequent burning and high grazing, Brachiaria covers 50
percent of the pasture even after 4 years after abandonment. But by 8 years after abandonment, there is only a small amount of grass and weed coverage in any of the systems, no matter what their grazing and burning history.
Impacts
The developed agroforestry systems provide a viable alternative for sustainable and permanent land use in central Amazonia. The expected result is a lower population pressure on the remaining forest resources, preservation of genetic resources in the Amazon and improved livelihood of the small farmers which are most vulnerable to global change.
Publications
- Fernandes, E.C.M., Biot, Y., Castilla, C. et al. 1997. The impact of selective logging and forest conversion for subsistence agriculture and pastures on terrestrial nutrient dynamics in the Amazon. Ciencia e Cultura Journal of the Brazilian Association for the Advancement of Science, 49 (1/2)(January/April): 34-47.
- Barros E, Neves A, Blanchart E, Fernandes ECM, Wendelli E, Lavelle P. 2003. Development of the soil macrofauna community under silvopastoral and agrosilvicultural systems in Amazonia. PEDOBIOLOGIA 47: 273-280
- Feldpausch, T.R., E.C.M. Fernandes, M.A. Rondon, S.J. Riha, E. Wandelli, and J. Lehmann. 2003. Tropical forest recovery following human disturbance in central Amazonia: post-pasture forest structure, canopy cover, biomass and nutrient dynamics. International Young Scientists' Global Change Conference, START [www.start.org] and Third World Academy of Sciences/ICTP, Trieste, Italy. p 83. November 16-19, 2003.
- Feldpausch, T.R., M.A. Rondon, E.C.M. Fernandes, and S.J. Riha. 2004. Carbon and nutrient accumulation in secondary forests regenerating from degraded pastures in central Amazonia. Ecological Applications In press.
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Progress 01/01/02 to 12/31/02
Outputs
We developed four prototype agroforestry systems involving twenty native tree and shrub species in combinations with major food crops and livestock. We successfully established these systems on degraded pastureland and evaluated their productive potential and environmental impacts over ten years. The farmer communities were involved in the initial diagnosis of land degradation and in the design of the prototype systems. Once the systems were established, farmers visited the systems for periodic evaluations and to provide advice on the management of the systems. Local university students and faculty participated in field measurements and system management. The aboveground biomass evaluation of the agroforestry systems (AFS) is complete. New, species-specific allometric equations have been developed for 19 tree and shrub components of the agroforestry systems. In the Secondary Forest plots, aboveground biomass (AGBM) was estimated using published allometric equations.
The Secondary Forest contained the highest AGBM at 111.9 Mg ha-1 followed by the Palm System (82 Mg ha-1), the fruit-based Home Garden (66.7 Mg ha-1) and the Silvopastoral system (32.5 Mg ha-1). Nutrient stocks in AGBM were highest in the Palm System for N and Mg at 468.2 and 98.2 kg ha-1 respectively; in the Home garden for K at 407.6 kg ha-1 and in Secondary forest for P and Ca at 71 and 439 kg ha-1 respectively. Forest soils store the highest amount of C (121 Mg.ha-1), followed by the AS2 system with 116Mg.ha-1. At the other extreme, soils under secondary vegetation and ASP2 system presented the lowest stock (106Mg.ha-1). Results in this study indicate that agroforestry systems permit a moderate recovery of soil C stock relative to the control under secondary vegetation. Conversion of forest to pastures resulted in drastic net reductions of methane oxidation by soils. Secondary forest also showed only negligible net methane sinks, comparable to those of degraded pastures.
Agroforestry systems AS1 (palm) and AS2 (fruit) allowed a recovery of methane sinks to around 50 percent of forest values, but the pasture based ASP reached only nearly 25 percent of forest sink strength (Appendix 2, Figure 7). The application of modest levels of P and Ca to recover degraded pastures could enhance methane sinks in the region. We developed a spatial simulation model of the dynamics of establishment of secondary forests in abandoned pastures for the Central Amazon. Our simulations show that the annual NPP of the pasture system was predicted to peak at 5 ton/ha/year, but when the woody weed Vismia invades, an NPP of up to 24 ton/ha/year can be achieved. These are the only long-term, complex agroforestry systems on degraded lands in the Amazon and local farmer communities, university students and policy makers are using them as the main source of information for developing and promoting improved agroforestry systems at forest margins in the Amazon. Our research findings
were synthesized and presented in an invited testimony to the House of Federal Deputies and Senators in Brasilia and the annual meetings of the American Society of Agronomy.
Impacts
Fifty-seven agricultural technicians, 200 undergraduates, 25 graduate students, and 5 postdoctoral scientists from Brazil and the US have been trained in the theoretical and practical aspects of designing and establishing complex agroforestry systems for the rehabilitation of degraded lands in the Amazon. Information on improved agroforestry system management that we obtained from 5 ha of research plots is now being applied across thousands of hectares across 5 municipalities in the southern Amazon where several thousand new migrants are establishing new farms. The delivery of our results and data to the new settlers is being coordinated by Dr. Peter May (Cornell alumnus) via a partnership involving local mayors, community associations, local non-governmental organizations and Cornell University and is funded by the Global Environmental Facility (GEF) of the United Nations. Total funding for the GEF project is US$ 6 million for the period 2002-2007.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
We are investigating options for rehabilitating the productivity of abandoned pasturelands in the Brazilian Amazon. The effect of Ca and P additions on soil and plant nutrient dynamics, total system carbon stocks, secondary species succession and soil and plant productivity is being evaluated. Two major land rehabilitation pathways are being explored. The first is to accelerate the regeneration of secondary forests on abandoned pastures and the second, to assess the productivity and sustainability of agroforestry systems on abandoned pastureland. Carbon sequestration will be determined both aboveground and within soils. The research results will contribute to the development of management strategies aimed at reducing tropical deforestation and rehabilitating already deforested and degraded lands. The four objectives of this project are (1) to test the relationship between nutrient dynamics, carbon sequestration, and trace gas and water fluxes in abandoned pastures and
managed agroforestry systems of the western Amazon; (2) to show how the relationships can be used to develop effective sustainable land management alternatives to degraded pastures in this region; (3) to provide information that will allow researchers and policy makers to project the impact of different land management scenarios in the western Amazon on changes in carbon and nutrient stocks and water; and (4) to strengthen local institutional capacity via training of local students and researchers Accomplishments: (1) Carbon and nutrient stocks in four agroforestry systems on degraded pastures measured (2) Allometric equations for biomass estimations in 19 agroforestry species developed, (3) Belowground C and nutrient stocks in agroforestry systems and degraded pasture vegetation measured, (4) Leaf area index and soil water dynamics in agroforestry systems and degraded pasture over 2 cropping seasons measured. The data show that in 9 years, the secondary vegetation on abandoned
pastures accumulated approximately 54t aboveground C per ha while the agroforestry systems accumulated between 9 and 32 t aboveground C per ha over the same time period. The agroforestry systems we tested sequestered C in the soil and over a ten year period increased soil C from 87% to 95% of the total soil C stocks in the primary forest. Conversion of forest to pastures resulted in drastic net reductions in methane oxidation by soils, almost eliminating net sinks during the sampled period. Secondary forest also showed only negligible net methane sinks, comparable to those of degraded pastures. This could be attributed to "leaks"coming from abundant termite mounds that are found in this vegetation. Agroforestry systems allowed a recovery of methane sinks to around 50% of forest values, but the pasture based ASP reached only nearly 25% of forest sink strength. The application of modest levels of P and Ca could enhance methane sinks in the region. Our research shows that methane fluxes
from termite mounds in secondary forests and in pasture sites are at least two orders of magnitude higher than recorded sinks by soils in the same plots.
Impacts
Our results are the first estimates for carbon and nutrient dynamics in complex agroforestry systems on degraded pastures in the Amazon. The data are currently being used to design improved agroforestry systems for new settlement areas at the southern margin of the Amazon.
Publications
- Ingram, J.S.I. and Fernandes, E.C.M. (2001) Managing Carbon Sequestration in Soils: A Note on Concepts and Terminology. Agriculture Ecosystems & the Environment. 87:111-117.
- Feldpausch, T., Fernandes, E.C.M., Rondon, M. and Riha, S. (2001) Carbon and nutrient accumulation in secondary forests regenerating on degraded pastures in the central Amazon. American Society of Agronomy. 2001 Annual Meetings, Charlotte, NC. Published Abstract.
- Gallardo, J., Luizao, F. and Fernandes, E.C.M., Wandelli, E.V. (2001). Carbon and nutrient stocks in roots under agroforestry systems and abandoned pasture vegetation in the central Amazon. American Society of Agronomy. 2001 Annual Meetings, Charlotte, NC. Published Abstract.
- McCaffery, K.A., Rondon, M., and Fernandes, E.C.M. (2001) Regenerating degraded land in the Amazon through the use of legume trees and fertilizer. American Society of Agronomy. 2001 Annual Meetings, Charlotte, NC. Published Abstract.
- McCaffery, K., Rondon, M. and Fernandes, E.C.M. (2000). Carbon and phosphorus stocks in agroforestry systems established on abandoned pastureland. American Society of Agronomy. 2001 Annual Meetings, Charlotte, NC. Published Abstract.
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Progress 01/01/00 to 12/31/00
Outputs
During the last two decades, over 50 million of hectares of Amazonian forest have been cleared and converted into pastures. Due to inappropriate establishment techniques and management, pasture productivity declines rapidly and the land is abandoned. Agroforestry systems are recognized as important land use alternatives to recover the productivity and ecosystem services of vast areas of degraded pasture land in the Amazon. We have designed and established 4 complex, multistrata agroforestry systems on the predominant soil type (clayey, kaolinitic Hapludox) in the western and central Amazon. The systems comprise the most common annual crops (rice, cowpea, cassava), pasture species (Brachiaria humidicola, B. brizantha and Desmodium ovalifolium), locally marketed fruit species (acerola, cupuacu, passion fruit, papaya, araca-boi), tree legumes (Inga edulis and Gliricidia sepium), and valuable timber species (mahogany, teak, brazil nut, colubrina). The 4 systems are coded
AS1 (Peach palm + fruit), AS2 (Brazil nut + fruit), ASPLI (mahogany + pasture low input), and ASPHI (mahogany + pasture high input). The Carbon stocks in aerial biomass in AS1 averages 22 Ton-C/ha being dominated by peach palm, while in AS2 Brazil nut alone contributes with 46% of the total C stocks of 25 ton C/ha, being significantly lower than biomass in secondary vegetation of the same age. ASP biomass has 11 ton C/ha. Both peach palm and Brazil nut not only have high C and nutrient stocks but also represent an important income of cash to the farmers. Root biomass is being assessed in all our plots. Present data indicates that at least 50% of all root biomass is concentrated in the top 20 cm of soil. There are noticeable differences among species regarding root C stocks, ranging from 1.6 ton-C/ha for Colubrina acreanaea to 0.7 ton C/ha in cupuacu). Root biomass in AS1 averages 6.1 ton/ha, being 1.45 in secondary vegetation and 0.92 in pastures of the ASP. Contribution of roots of
the trees in ASP and in the AS2 is being completed. Litter is an important pool for C and nutrients in the systems under study. Data from litter accumulated during the dry season show that the AS2 produces more litter-C (3.3 ton/ha) than ASP (2.4 ton/ha) or AS1 (2.2ton/ha) but is significantly lower than stock in litter from secondary vegetation ( 3.9 ton/ha). Nitrogen stocks (kg/ha) are respectively 83, 75, 73 and 45 in secondary vegetation, ASP, AS2 and AS1. Other nutrients follow similar relative distribution patterns. Litter biomass accumulated during the rainy season is only about a half of values in the dry season. Initial measurements of soil physical properties show that palm species cause compaction in the top layers of the soil, as evidenced by increased resistance to penetration ( 220- 280 kgf) compared to values under secondary vegetation (120-150 kgf). Brazil nut seems to have a decompacting effect in soils, showing low values of resistance to penetration (100-120 kgf).
Our measurements show that due to the high net annual infiltration, around 150 - 200 kg/ha of Dissolved Organic Carbon (DOC) are removed from the systems each year.
Impacts
A seminar of the emerging research results was presented to a Select Committee of Brazil's Congress in Brasilia, Brazil. Federal and State Senators are currently debating a plan to significantly increase funding for infrastructure development in the Brazilian Amazon. Current land use change models predict that the new infrastructure will result in major deforestation, land degradation, and significant negative impacts on regional climate and biodiversity.
Publications
- ECM Fernandes, SJ Riha, J Duxbury, M Rondon, E Wandelli, R. Perin, S. Garcia, F. Luizao, R. Luizao. 2000. Carbon and Nutrient Stocks and Soil Water Dynamics in Abandoned Pastures and Agroforestry Systems in the Central Amazon. Proceedings of the NASA LBA-Ecology Science meeting, June 25-29, 2000. Belem, Brazil.
- Ilse Lieve Ackerman, Juliete M. T. Queiroz, Marco A. Rondon, Erick C. M. Fernandes, Susan J. Riha, Michael G. Villani, and Elisa Wandelli. 2000. Carbon storage and land productivity in the Central Amazon: The role of mound-building termites. Proceedings of the NASA LBA-Ecology Science meeting, June 25-29, 2000. Belem, Brazil.
- Carbon Stocks in Agroforestry Systems Established on Abandoned Pastureland. 2000. McCaffery, Karen A., E.C.M. Fernandes*, Rondon, M.A. and Wandelli, E.V. Proceedings of the NASA LBA-Ecology Science meeting, June 25, 2000. Belem, Brazil.
- McCaffery, Karen A., E.C.M. Fernandes, M.A. Rondon and M.S. Cravo. 2000. Increasing Carbon Sequestration on Deforested Land Through the Use of Legume Trees and Fertilizer Inputs. Proceedings of the NASA LBA-Ecology Science meeting, June 25 2000. Belem, Brazil.
- Steven A. Welch, Susan J. Riha, John M. Duxbury, Marco A. Rondon and Erick C.M. Fernandes. 2000. Light and water capture by secondary vegetation communities on abandoned pastures in the Manaus region. Proceedings of the NASA LBA-Ecology Science meeting, June 25 2000. Belem, Brazil.
- Fernandes, E.C.M. 2000. The Evolution of Managed Fallow Systems in the Tropics. Proceedings of the "Fallow Management in the Tropics" symposium. 2000 Annual Meeting of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. Minneapolis, Minnesota (November 5-9, 2000)
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Progress 01/01/99 to 12/31/99
Outputs
The graduate students arrived on site in May 1999 and the field site was characterized by August 1999. Specific experiments to evaluate soil moisture dynamics, soil and vegetation carbon and nutrient stocks have been initiated and data collection is in progress. Do to a problem with equipment importation into Brazil, weather measurements and observations on root dynamics in agroforestry systems will start in 2000.
Impacts
There are 60 miilion hectares of abandoned pasture land in the Brazilian Amazon. Our results will provide information to research and development agencies and policy makers on potential alternatives to rehabilitate these degraded lands and deflect the deforestation pressure from primary forest.
Publications
- No publications reported this period
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Progress 01/01/98 to 12/31/98
Outputs
This project has been pending final approval of the memorandum of understanding between NASA and the government of Brazil. No field activites have been initiated. Partial funding was received for tuition and subsistence of graduate students who will be proceeding to the field in April of 1999. *the start date indicated above needs to be changed to January 1999, to reflect the delay in obtaining final approval and complete funding from NASA
Impacts
(N/A)
Publications
- No publications reported this period
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