Florencia Montagnini Professor in the Practice of Tropical...

Yale School of Forestry & Yale School of Forestry & Environmental StudiesEnvironmental Studieshttp://http://www.environment.yale.eduwww.environment.yale.edu

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LatinLatin AmericaAmericaFlorencia Montagnini

Professor in the Practice of Tropical ForestryDirector, Program in Tropical ForestryGlobal Institute of Sustainable Forestry

Yale School of Forestry & Yale School of Forestry & Environmental StudiesEnvironmental Studies

Conversion of forests to pastures is one of the most widespread land-use changes in the Latin American tropics.

Between 30% and 60% of these pastures have been degraded by inadequate management.

Degraded pastures in Quindio, Colombia.

Photos: Alicia Calle


Degraded pasture fields near Guapiles, Costa Rica

Pasture degradation is the result of the interaction of:

•lack of or bad management•overgrazing (excess stocking, inadequate animals or breeds)•soil compaction (soils are not adequate, wrong management)•soil erosion (as result of compaction)•weed invasion (as result of all the above)•decrease in soil fertility (especially P, N)


Silvopastoral systems (SPS), especially if they include native tree species, can contribute to restore soils, productivity and environmental services of degraded pastures. We present results of long-term studies on rehabilitation of degraded pastures using native tree species that are well suited to SPS in Costa Rica.

Degraded pasture, dominated by non- productive ferns and grasses more than 20 years after pasture abandonment.

Photo: Daniel Piotto


Methods

Native tree species were planted in mixed and pure plantations in 1991-1992 on degraded pastures. Twelve species were planted, 4 of which were eliminated by pests and disease; the 8 following remained:

Plantation 1: Vochysia guatemalensis (Vochysiaceae) and Jacaranda copaia (Bignoniaceae); Plantation 2: Dipteryx panamensis (Fabaceae), Terminaliaamazonia (Combretaceae) and Virola koschny(Myristicaceae); Plantation 3: Balizia elegans (Mimoseaceae), Hyeronimaalchorneoides (Euphorbiaceae) and Vochysia ferruginea(Vochysiaceae).


Methods, cont’

Height and diameter at breast height (dbh) were measured annually. Basal area, volume, aboveground biomass, and carbon storage were measured/calculated. Litterfall was measured using litter traps for 12 months in each plot.Soil was sampled below each of the pure and mixed plots, in unplanted abandoned pastures, and adjacent 20 year old secondary forest.


Young mixed plantation of native species (Jacaranda copaia, Calophyllum brasiliense “Cedro Maria”, and Vochysia guatemalensis “Mayo/Chancho”, on degraded pasture. La Selva, Costa Rica (10 22'N, 83 59'W, 35-137 masl, 24°C, mean annual precipitation 4000 mm).

Soils are Fluventic Dystropepts, deep, well-drained, stone-free, with low or medium amounts of organic matter (2.5%-4.5%), acidic (pH in water <5.0), and low fertility.


Mixed plantation, product diversification and environmental benefits.

Terminalia amazonia, 10 years, timber price comparable to teak in Panama


Virola koschnyi, 14 years, medium timber quality, dense crown.

Vochysia ferruginea , 14 years, controls erosion, increases soil N and OM content.


Vochysia guatemalensis: 27.4 cm dbh in pure plantation and 37.9 cm in mixed plantation at 16 years. Reduces soil erosion. Adapted to soils of very low fertility and poor drainage. Harbors diversity. Calculated NPV at 16 yrs: $6,000/ha, with an internal rate of return of over 14% (Montagnini and Piotto, 2010) Photo: Daniel Piotto


Tree density and volume in 16-year-old pure and mixed plantations. La Selva, Costa Rica. Source: Montagnini and Piotto, 2010

0

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Density (Indiv/ha) Volume (m3/ha)


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Car

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Carbon storage in 16-year-old pure and mixed plots, La Selva. Source: Montagnini and Piotto, 2010.


At 16 years, mixed species plots were more productive than pure plantations in wood volume and carbon sequestration. Vochysia guatemalensis is preferred by farmers for its good growth on poor, acid, poorly-drained soils and high-value timber, grew particularly well. Virola koschnyi, Terminalia amazonia, Vochysiaferruginea, and Hyeronima alchorneoides all grew well and are preferred by farmers for their good growth and high quality timber (Redondo-Brenes 2007). Rotation lengths are 10 years for J. copaia, 20 yrs for V. guatemalensis, 25 yrs for T. amazonia, V. ferruginea, H. alchorneoides, V. koschnyi, and B. elegans; and 40 yrs for D. panamensis.


Organic Matter (%)

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N (%)

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Soil Organic Matter and Nitrogen in 15-16 year old mixed and pure plantations. La Selva, Costa Rica. Source: Montagnini 2008.


Impacts on soil fertility

At 3 years, plantations soils had already improved: in the top 15 cm, total N was 0.23% - 32% and SOM was 5.5% - 6.6%, while abandoned pastures had only 0.23% N and 4.8% OM.

Soil in adjacent 20-year-old secondary forest was similar to that of 3-year-old plantations: 0.33% (N) and 7.6% (MO).

The highest OM, N, Ca, and P values were below Vochysiaferruginea, the species that produced the greatest quantity of litter.

Mixed plots had intermediate levels of OM and nutrients.


Annual litterfall and accumulation in pure and mixed plantations. La Selva, Costa Rica.

0

3000

6000

9000

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paia

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Annual litterfall (kg/ha) Forest floor littter (kg/ha)


Litterfall, decomposition, and accumulation

Litterfall was greatest in V. guatemalensis, T. amazonia, H. alchorneoides and V. ferrugineaDecomposition was fastest in T. amazonia, D. panamensis and B. elegans, where litter decomposed completely in 12 months. Decompositon was slowest in V. guatemalensis, J. copaia and V. koschnyi. Litterfall, decomposition, and accumulation were intermediate in mixed plantations.


Hyeronima alchorneoides in a SPS in the Northern Caribbean region of Costa Rica. Photo: Alvaro Redondo


Dipteryx oleifera in a SPS in the Northern Caribbean region of Costa Rica. Photo: Alvaro Redondo


Use of these tree species in silvopastoral systems

T. amazonia, D. panamensis, and Balizia elegans provide rapid liberation of soil nutrients through litter, encouraging growth of natural or seeded grass species.

Hyeronima alchorneoides forms a open crown, and its nutrient cycling makes it an appropriate choice for agroforestry systems, including SPS.

Virola koschnyi and Terminalia amazonia form denser crowns, but can be included in lower-density SPS.

These trees are used in SPS with beef cattle when the trees are 2-3 years old, when damage by cattle is expected to be minimal.

Native grasses such as Paspalum fasciculatum, and the exotic Cynodonnlenfuensis, Panicum maximum, Pennisetum purpureum, Brachiariaspp., Melinis minutiflora, and Ischaemun indiana grow well beneath these species.


Conclusions

Degraded pastures can be replaced with SPS using native trees that improve soils, control erosion, and produce high-quality timber, providing both restoration and productivity.

In Costa Rica, farmers can also benefit from tree plantations (including those in SPS) with payments for environmental services (PES), due to the C sequestration performed by these species.

In SPS, short-term economic products are obtained from cattle products, thereby accelerating returns on investment, providing an added incentive for reforesting degraded sites.


Conclusions cont’

In these systems, the cattle feed on grasses that grow naturally below the plantation.The may include native grasses such as Paspalum fasciculatum, or the exotic Cynodon nlenfuensis, Panicum maximum, Pennisetum purpureum, Brachiaria spp., Melinis minutiflora, and Ischaemun indiana.Future research should seek more productive SPS using grasses and other species better fit to these conditions.


•Some alternatives to increase pasture productivity include models developed by EMBRAPA in Brazil, CIAT in Colombia, CATIE in Costa Rica; all based on intercropping productive grasses with legume herbs.

•Example, intercropping the legume herbs Pueraria phaseoloides and Desmodium ovalifolium with productive grasses such as Brachiaria humidicola and B.decumbens.


In the Atlantic humid region of Costa Rica, CATIE has promoted the use of mixtures of Brachiaria brizantha + Arachis pintoi.

Arachis pintoi is a species of peanut that is good as a soil cover, fixes Nitrogen, protects against soil erosion, and increases pasture and cattle productivity.


Conclusions cont’

Different species of trees planted in SPS have different impacts on soils, nutrient cycling, and productivity, as well as different characteristics that can affect their suitability for SPS.Planting multiple tree species may offer the benefits of each species, as well as the advantage of providing a diversity of products, an important factor to farmers.


Thank you!Thank you!

Questions?Questions?

Photos: Alicia Calle


References

•Bouman, B. A. M., Nieuwenhuyse, A and Ibrahim, M. 1999. Pasture degradation and restoration by legumes in humid tropical Costa Rica. Tropical Grasslands 33: 98-110.•Calle, A., Montagnini, F. and A. F. Zuluaga. 2009. Farmer’s Perceptions of Silvopastoral System Promotion in Quindío, Colombia. Bois et Forets des Tropiques 300(2): 79-94.•Lam Bent, H. S., Montagnini, F., Finney, C. 2010. A comparison of growth and yield among four native and one exotic tree species on plantations on six farms at Las Lajas, Chiriqui Province, Western Panama. Journal of Sustainable Forestry. In press. •Montagnini, F., González, E., Rheingans, R., Porras, C., 1995. Mixed and pure forest plantations in the humid neotropics: a comparison of early growth, pest damage and establishment costs. Commonwealth Forestry Review 74(4), 306-314. •Montagnini, F., Ugalde, L., Navarro, C., 2003. Growth characteristics of some native tree species used in silvopastoral systems in the humid lowlands of Costa Rica. Agroforestry Systems 59, 163- 170.•Montagnini, F., 2008a. Management for sustainability and restoration of degraded pastures in the Neotropics. En: Myster, R., (Ed.), Post-agricultural succession in the Neotropics. Springer, New York, pp. 265-295.•Montagnini, F., 2008b. Soil sustainability in agroforestry systems: experiences on impacts of trees on soil fertility from a humid tropical site. En: Batish, D.R., Kohli, R.K., Jose, S., Singh, H.P., (Eds), Ecological Basis of Agroforestry. CRC Press, Taylor and Francis, Boca Raton, Florida, pp. 239-251. •Montagnini, F. & D. Piotto. Mixed plantations with native trees on abandoned pasture lands: restoring productivity, ecosystem properties and services in a humid tropical site. In: S. Günter, B. Stimm, M. Weber, R. Mosandl (eds.). Silviculture in the Tropics. Springer, Berlin-New York. In press.•Redondo-Brenes, A., 2007. Growth, carbon sequestration, and management of native tree plantations in humid regions of Costa Rica. New Forests 34, 253-268.

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