Teak on EL COBANO. Monitoring report. Owner Maderas El Cobano S.A. (Costa Rica) Participant Association Euro Greenmix Fund A (The Netherlands)

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1 Monitoring report Teak on EL COBANO 2007 Owner Maderas S.A. (Costa Rica) Participant Association Euro Greenmix Fund A (The Netherlands) SilvoConsult E.S. SRL November 2007

2 SUMMARY Once again, the Cobano-project has received its yearly monitoring visit in order to analyse the overall stand development of the teak, the maintenance and the projections for future thinning and final cut. The visit took place on October 17 th of 2006, 12 months after the last visit in October General maintenance looked as good as, or even better than, during prior visits. Neither the thinning operation during the first half of 2007 nor the change of foreman seems to have affected the achieved maintenance rhythm. Repetition of the pruning is necessary but seems to be planned for the second half of 2007, according to the 1&2 quarter 2007 report of ArteVerde. The high pruning is in this case the most urgent due to the presence of thick dead branches that reduce wood quality. The teak syndrome is still present, although little intensive and seems to be walking around. In some areas the symptoms disappeared, but now units like T2, T7 and T8 show dead trees and small and/or dead crowns. The low plains of T11, T12 and T13 show the most vigorous trees. According to the 15 permanent measurement plots (PMP), the syndrome affects 1,3% of the trees. Thinning has been more intensive than projected. Tree density was brought down independent of the basal area before thinning. Average project density is 327 trees/ha but the density according to the PMP fluctuates independent of the site class, between 227 and 406 trees/ha. The projections prior to the thinning aimed at 325 trees/ha for the plains and 390 trees for the slopes. As a consequence, no regular thinning will be necessary anymore before the final cut whether in year 20 or later on. Corrective thinning may be considered in the future on incidental spots where actual density is above the projected. The projections of the stand development had to be adjusted downwards with 4% for the slopes and 2% for the plains to represent actual stand development. Projected volume for a final cut in year 20 now gives m³ of timber over 15 cm diameter. For year 25 this could be m³. The new non-teak plantings show a satisfactory development. However, commercially, the expectations should not be too high since market does not broadly accept these species yet from plantations. Also the processing of these timbers from relatively young plantations is still in an experimental phase. On the other hand the laurel looks bad to regular. Diameters are low and so is the log quality due to bad shaped stems. Both will negatively affect revenues. SilvoConsult SRL Nov 07 Page 2 of 16

3 Index SUMMARY 2 1 INTRODUCTION 4 2 STAND DEVELOPMENT maintenance Teak health teak growth Current project volume 9 3 GROWTH PREDICTIONS 10 4 NATIVE SPECIES 12 5 CONCLUSIONS AND RECOMENDATIONES 14 5 ANNEXES 15 Table 1 Resume of stands measurements October 2007 per site class 7 Table 2 Comparison of stand measurements October 2007 and October 2006 per site class 8 Table 3 The total standing commercial teak volume in pure teak stands on Cobano 9 Table 4 Growth and production scenario for High and Low plains 10 Table 5 Growth and production scenario for Slopes 10 SilvoConsult SRL Nov 07 Page 3 of 16

4 1 INTRODUCTION On October 17 th, the Cobano-estate received its yearly monitoring-visit, exactly 12 month after the prior in This time special attention went to the effects of last years thinning on the plantation figures and to the behaviour of the wide spread problem in teak known as teak-syndrome. During the one-day visit, the 15 permanent monitoring plots (PMP) have been re-measured and remarked. This has been the fifth measurement of exactly the same plots so a good idea can be formed on the year to year development of this plantation. This paper first describes the state of the plantation maintenance and of the sanitary condition of the teak, followed by an analysis of the development of the teak stands in the PMP and of the projections for the next 8-13 years. Furthermore, some attention will be paid to the non-teak plantings. SilvoConsult SRL Nov 07 Page 4 of 16

5 2 STAND DEVELOPMENT 2.1 MAINTENANCE General maintenance looks as good as or even better than during prior visits. Neither the thinning operation during the first half of 2007 nor the change of foreman seems to have affected the achieved maintenance rhythm. Undergrowth is sometimes high but by no means harmful for the health or development of the teak. Mowing is opportune, which can be observed most of all from the absence of the damaging climbers in the tree crowns. In a plantation of this age and tree height, only climbers are able to affect the standing trees. Despite the thinning, roads are in a very good condition. The brushwood in the corridor between T13 and T11 has finally been opened, allowing the road to dry and to be accessible. Repetition of the pruning is necessary but has been planned for the second half of 2007, according to the 1&2 quarter 2007 report of ArteVerde. The high pruning is in this case the most urgent due to the presence of thick dead branches that reduce wood quality. On the lower part of the trees adventitious branching takes place. This is a well known problem for plantation management with especially teak trees but for example also with oak trees. These branches sprout every year after the dry season on the old pruning scarves. After thinning and opening of the canopy the sprouting intensity increases due to higher exposure of the lower stem to sun light. However, these are living branches that, when pruned opportune will not effect the wood. Drainages are being cleared at a regular base. No stagnated water could be observed in between the teak. 2.2 TEAK HEALTH The two most important issues to be analysed by means of the monitoring are the development of the teak stands on the one hand and the vitality of the trees on the other. The health and vigour of the trees will be treated in this section. The so-called teak syndrome has been attacking the project for several years now. As in most teak projects, the development of the syndrome does not follow a fixed pattern. Some areas have been affected severely like T3. But in others the symptoms have disappeared. It seems that the syndrome is walking around. SilvoConsult SRL Nov 07 Page 5 of 16

6 In October 2006, spots of dead trees were observed in T3 and T11. The rest of the plantation showed good colour, leaf size and leaf quantity. During the last visit in October 2007, the panorama looked quite different. All dead and sick trees had of course been eliminated during this years thinning operation. This implies that any present sick or dead tree is a new case. T11 looked this time sound, while T2 and T8 showed a very poor vigour. Trees had few and yellowish leafs, showed dead branch ends as well as dead branches. Several trees were already dead. T7 did not look so bad in general, but showed severe mortality on its east-slope. T3 and T12 (at the base of the slope) showed once again dispersed mortality while the surrounding trees look very healthy. The trees in the low parts of T11, T12 and T13 are still showing the best colour, leaf size and quantity. This is in contrast with the impression during the first visit seven years ago, prior to the management by ArteVerde. At that time the low parts were full of dead and uprooted trees, while standing trees had small pale green leafs. Intensive draining in combination with a soil of better quality has resulted in a recovery of tree health and a steady development. Problems now seem to be increasing on the slopes and high plains. Excessive humidity is not so much of a problem in these areas. But soils have an extreme high clay content and are chemically less favourable for teak. This implies that oxygenation of the soil is low and tree roots suffer from low oxygen and high humidity even during the first days to weeks of a dry spell. The root quality deteriorates and the absorption of the scarcely available nutrients is being complicated. The latter is nor scientifically proven, neither are the possible solutions. In the meanwhile, calcium-carbonate and controlled burning should be applied as cheapest and best known options for maintaining the quality of the stands. In numbers, only 4 trees of all the plots (3 in T7-slope and 1 in T7-high plain) were dead or dying which is equal to 1,3% of the measured trees. This is twice the percentage of last year but still a normal figure for forestry plantations. Projecting this mortality figure on the whole project would result in some 240 dead trees. ArteVerde mentions that only 40 trees were detected and cut during last thinning. However, both the mortality date (0,7% or 170 trees) during monitoring 2006 and the 3% (729 trees) of removed dead, sick or thrown over trees by ArteVerde in 2006 indicate that the figure of 40 must be an underestimation. Once again, nothing can be said about the future. Mortality may raise or may reduce like during the year In the meanwhile, a procedure should be developed for the wood of the dead and dying trees. Independent whether there will be a thinning in 4 years and/or a final cut in 8 years, a considerable amount of trees and their wood will get worthless due to mortality. Individual tree size is getting good enough to make local sale on a small scale interesting at least once a year. SilvoConsult SRL Nov 07 Page 6 of 16

7 2.3 TEAK GROWTH Table 1 shows the outcomes of the measurement of the 15 permanent monitoring plots, while table 2 makes a comparison with the monitoring of October 2006, before and after thinning. The latter has been calculated by simply removing the thinned trees from the 2006 data. This way the effect of thinning on the average diameter, basal area and volume can be distinguished from the effect of the growth of the remaining trees. Estimating the planting date of the trees on September 1995, the trees were 145 months or 12,1 years old at the time of measuring. In spite of the thinning operation, differences between the different plots within the same site class were not reduced. The growth projections indicated a tree reduction to 325 trees/ha on the plains and 390 trees/ha on the slopes. This would have implied that in several plots no thinning was to be executed. However, all plots have been subject to reduction. The same will have happened in the different units outside the plots, where density was low as well. Site class Unit Age (yr) Trees DBH (cm) Av. Height (m) Basal area (m²/ha) Total volume (m³/ha) Vcom >15 cm (m³/ha) MAI DBH (cm/yr) MAI V>15 (m3/ha/yr) High plain T % High plain T % High plain T % High plain T % Average 12 26% Slope T % Slope T11b 12 29% Slope T11a 12 25% Slope T % Slope T % Slope T % Slope T % Slope T % Average 12 26% Low plain T11b 12 18% Low plain T % Low plain T % Average 12 21% Project average 12 25% Where Volume: DBH: MAI: Vcom: Figures refer to estimations of round wood over bark Diameter at breast height Mean Annual Increment Commercial volume of timber over 15cm diameter Table 1 Resume of stands measurements October 2007 per site class SilvoConsult SRL Nov 07 Page 7 of 16

8 In average, tree density was reduced (according to the PMP) to 327 trees per hectare or 25,2%. The tree count of ArteVerde results in 23,8% (standing trees divided by planted trees) or 309 trees per hectare. This implies that the present tree density is well below the projected numbers for age 12 ( trees). Some PMP have up to 406 trees/ha (T5-high plain and T7-slope) and another only 227 trees (T11-low plain). There is no relation between site class and density. The tree count of ArteVerde shows extremes of 258 in T10 (most of it classified as slope) and 375 trees in T2 (both high plain and slope). As a result, the basal area (BA) and consequently the volume show the same differences. BA is between 9,5 and 15,4 m²/ha and the commercial volume between 42 and 93 m³/ha. Average tree diameter increased between 0,4 and 1,0 cm due to thinning. This means that, as standard, the trees of lesser quality (read: minor diameter) were thinned. Average diameter increment of the remaining trees during last year was between 0,4 and 0,8 cm. The accumulated diameter increment resulted therefore in 0,8 to 1,8 cm. The trees on the slopes show a higher average diameter increment than those on the high plains. This has been the tendency during the last 3 years. Site class Trees October 2007 October 2006 after thinning Basal Vcom Basal Vcom DBH Area >15cm Trees DBH Area >15cm (cm) (m²/ha) (m³/ha) (cm) (m²/ha) (m³/ha) Trees October 2006 before thinning Basal Vcom DBH Area >15cm (cm) (m²/ha) (m³/ha) High plain Slope Low plain Average Where Volume: Figures refer to estimations over bark DBH: Diameter at breast height MAI: Mean Annual Increment Vcom: Commercial volume of timber over 15 cm diameter Table 2 Comparison of stand measurements October 2007 and October 2006 (before and after thinning) per site class Due to the fact that both, low density areas and slopes, were drastically thinned, actual basal area is sometimes rather low. On the other hand the figures show that the basal area increment of the remaining stands has been between 0,6 m² on the high plains and slopes and 0,8 m² on the low plains per hectare during the last year. SilvoConsult SRL Nov 07 Page 8 of 16

9 2.4 CURRENT PROJECT VOLUME In Table 3 a comparison is being made between the total actual commercial volume and that before and after the thinning of According to these figures during the 2007 thinning about 669 m³ of roundwood over 15 cm diameter was extracted. This should be equal to 736 m³ of roundwood over 13 cm diameter. With an estimated loss in the field of 20% due to bad shaped logs, too short pieces and other problems this volume would be 589 m³. Site class Area (ha) Oct 2007 Vcom/site class (m³/ha) Oct 2007 Vcom/site class (m³) Oct 2006 After thin Vcom/site class (m³/ha) Oct 2006 After thin Vcom/site class (m³) Oct 2006 Before thin Vcom/site class (m³) Oct 2006 Before thin Vcom/site class (m³) High plain Slope Low plain Table 3: The total standing commercial teak volume in pure teak stands on Cobano ArteVerde mentions in the 1&2 quarter report of 2007 a sales volume of 399 m³-hoppus which is equal to about 627 m³ roundwood over 13 cm diameter. This implies that actual monitoring data and real production data are fairly comparable. Last years projection for the thinning was 464 m³ of roundwood over 13 cm diameter which implies that the thinning operation was more intensive than planned. SilvoConsult SRL Nov 07 Page 9 of 16

10 3 GROWTH PREDICTIONS The expectations for the future of the development of the stands have been calculated year by year in Annex 1 and 2 for High and Low plains on the one hand and Slopes on the other. By absence of literature with growth curves for the Atlantic and Northern Zone based on growth measurement in stead of extrapolation, no hard calculations can be made. Once again the projections had to be adjusted downwards in order to represent current development: 2% in case of the plains and 4% in case of the slopes. As mentioned in 2.4 the basal area increment during last year was only 0,6 to 0,8 m². Recovery of the basal area is thus very slow. At this rate, some slopes will not reach 16 m²/ha at age 20. Productivity will therefore be below capacity during several years. On the high plains basal area will reach m²/ha if present tree development maintains. The same will happen on the low plains despite their higher recovery rate. For this reason the thinning for year 15 has been eliminated. This implies that tree density will be higher at final cut than projected last year. The effect of the higher density on the diameter increment will be minimal since actual basal area allows a maximal development of the individual trees. It is common in plantation forestry to reach the final cut with a basal area well above 22 m². On the plains this may be the case on some spots if final cut is executed at year 25. The elimination of the last thinning also results in somewhat higher volumes. In case of, for example, the plains, the actual projection shows a volume increment of the final cut in year 20 from 148 to 157 m³/ha in comparison to last years projection. Table 4 Growth and production scenario for High and Low Plains Remaining stand Site production T Trees DBH Height BA Vc Area Vc (yr) (Nr/ha) (cm) (m) (m2/ha) (m3/ha) (ha) (m3) , Table 5 Growth and production scenario for Slopes Remaining stand Site production T Trees DBH Height BA Vc Area Vc (yr) (Nr/ha) (cm) (m) (m2/ha) (m3/ha) (ha) (m3) SilvoConsult SRL Nov 07 Page 10 of 16

11 Table 4 and 5 show a resume of the new schedules. A comparison has been made of a final cut in year 20 or in year 25. On basis of actual stand development, a final cut in year 20 would produce 157m³/ha on the plains and 108m³/ha on the slopes. Postponement of the final cut to year 25 would give an increment of the volume per hectare of m³. Higher volumes, thicker trees, higher heartwood content and higher market prices could be reasons for such a rescheduling. On the other hand, some areas (like the plains of T5 and T7) show at this moment tree densities far above the average. This might imply that these should be intervened within a few years resulting in a spot-like small scale thinning operation in order to level the tree density distribution all over the farm. However, only the spots with excessive canopy closure should be intervened. SilvoConsult SRL Nov 07 Page 11 of 16

12 4 NATIVE SPECIES The native species have never been included in the monitoring. Though, the board of EGFA has asked for an opinion of the consultant on the development and future of these trees. No numeric data have been gathered but on basis of experiences gathered at other projects a few points can be mentioned. Laurel The Laurel shows generally a bad to regular development. In Costa Rica, Laurel is commonly used in carpentry and construction. Minimum size for these purposes is 15cm diameter at the top of a log. The logs should have at least 2,15m although 2,5-3,3m is the standard length. Shorter logs can be sold against lower prices. The fact that most logs are relatively thin will affect the overall sales price. Both minimum length and diameter will be a problem for the Cobano-Laurel. Trees of better diameters are often bad shaped. So in general, trees will produce low volume consisting of low diameters. Economic returns will therefore be low. I wonder if it would not be wise to plant a species like Cebo (also called Chancho) in between the laurel, both on bad and better sites. This is the species of the zone. In the low plains, especially in T12 and T13, there is a lot of natural regeneration of this species and not withstanding the shade from the teak, the regeneration shows a vigorous growth and already a good size. It would not be necessary to eliminate the laurel. Growth of Cebo is rapid (like Melina) and the timber is very well accepted in Costa Rica for carpentry, construction and in case of the smaller diameter for pallets. Final cut can be executed between year 10 and 12. Almendro The objective of the Almendro plantings is merely as enrichment planting: to improve the quality of the existing ecosystems. On the mid-term they are going to produce seeds for birds and on the long term also nestling places. Timber production should no be considered as a possibility since growth is low and wood properties of young Almendro can in no way be compared with mature Almendro. Roble coral and Pilón Both Roble and Pilón are attractive timber species with a growth rate that makes planting attractive. However, there is little experience with the sawing of young Roble and Pilón. Young, in this case, also includes ages Personal experience is that the timber has a lot of tension at lower age and that use in normal sizes (2,5 to 3,3 m) is limited. On the other hand prices for plantation timber have not been fixed. Although young Pilón is being accepted for its colour, Roble has not the same acceptance since its colour at younger age does not compare with the Roble of the natural forest. Minimum accepted size for both species at this moment is 20cm diameter at the top end of SilvoConsult SRL Nov 07 Page 12 of 16

13 each log. Plantation timber of both species is now being used for pallets since this product allows short pieces. The development of the planted trees is satisfactory. Acacia mangium Acacia is not a native species in Costa Rica. However, the species has been planted during the last 20 years in Costa Rica. Since several years the species is being planted on larger scale by foreign companies in view of its wide acceptance on the world market. Prices are however relatively low. The quality of the trees seems to be problematic. The species suffers in the Northern Zone of heart rot and bleeding of the knots. It is however a good alternative for poor soils. Being a nitrogen-fixer, Acacia grows on extremely bad sides. SilvoConsult SRL Nov 07 Page 13 of 16

14 5 CONCLUSIONS AND RECOMENDATIONES Like last year, the teak stands on the Cobano-Estate show good maintenance. No harmful undergrowth is present, the pruning is being executed properly and drainages and roads are in a good condition. The appearance of the teak has two faces: very healthy and rather poor. The so-called teak syndrome can be found each time on other sites. At some spots it has stabilised, at others it disappeared and some spots have been attacked recently. This only indicates that any possible and economically viable measure should be taken and repeated to prevent and counter-attack the problem: controlled burning, calcium-carbonate applications, improved drainages and any other option that may arise. It is totally unknown how the problem will develop, so the only option is to proceed with preventive measures. The mortality due to the syndrome is not very elevated and quite concentrated to a few spots. A procedure should be developed for the identification, extraction and sale of sick and dead trees as well of those that are thrown over by the wind. Trees are all reaching commercial sizes and time lap until regular thinning or final cut will in most cases result in total loss of the wood and the possible revenues. Actual stand density has become more inconsistent even though the thinning of Most of the plantation is very open now and will not need another thinning intervention before the final cut. The spots with higher densities could be thinned in a view years although this will not be necessary from sanitary point of view. Any intervention should not follow general criteria, but should be analysed area by area, zone by zone. 8 th of November 2006 Aguas Zarcas Erik Schinkel SilvoConsult SRL Nov 07 Page 14 of 16

15 5 ANNEXES ANNEX 1: PRODUCTION ESTIMATIONS FOR SITE CLASSES: HIGH PLAIN AND LOW PLAIN REMAINING STAND THINNING ACCUMULATED STAND T Trees DBH Height BA Vt Vc BA Trees Trees DBH BA Vc BA Vt V15 MAI-Vc CAI-Vc (yr) (Nr/ha) (cm) (m) (m2/ha) (m3/ha) (m3/ha) (%) (%) (Nr/ha) (cm) (m2/ha) (m3/ha) (m2/ha) (m3/ha) (m3/ha) (m3/yr/ha) (m3/yr/ha) SilvoConsult SRL Nov 07 Page 15 of 16

16 ANNEX 2: PRODUCTION ESTIMATIONS FOR SITE CLASSE: SLOPES REMAINING STAND THINNING ACCUMULATED STAND T Trees DBH Height BA Vt Vc BA Trees Trees DBH BA Vc BA Vt V15 MAI-Vc CAI-Vc (yr) (Nr/ha) (cm) (m) (m2/ha) (m3/ha) (m3/ha) (%) (%) (Nr/ha) (cm) (m2/ha) (m3/ha) (m2/ha) (m3/ha) (m3/ha) (m3/yr/ha) (m3/yr/ha) SilvoConsult SRL Nov 07 Page 16 of 16