EFFECTS OF HARVESTING ON THE STRUCTURE OF

A NEOTROPICAL WOODY BAMBOO (Otatea: GUADUINAE) POPULATIONS

 

José Martín Vázquez-López, Heike Vibrans, Edmundo García-Moya,

Juan Ignacio Valdez-Hernández, Angélica Romero-Manzanares and Ramón Cuevas-Guzmán

 

José Martín Vázquez-López. M.Sc., Colegio de Postgraduados en Ciencias Agrícolas (CPCA), Montecillo, México. Professor- Researcher, Departamento de Ecología y Recursos Naturales, Centro Universitario de la Costa Sur, Universidad de Guadalajara, México. Address: Apartado Postal 108, Autlán de Navarro. Jalisco 48900, México. e-mail: mvazquez@cucsur.udg.mx

 

Heike Vibrans. Ph.D., University of Bonn, Germany. Professor- Researcher, Programa de Botánica, CPCA, Montecillo, México. e-mail: heike@colpos.mx Edmundo García-Moya. Ph.D., Oregon State University, USA. Professor-Researcher, Investigador, Programa de Botánica, CPCA, Montecillo, México. email: edmundo@colpos.mx

 

Juan Ignacio Valdez-Hernández. Ph.D., University of Queensland, Brisbane, Australia. Professor- Researcher, Programa Forestal, CPCA, Montecillo, México. e-mail: ignaciov@colpos.mx Angélica Romero-Manzanares. Ph.D., Universidad Nacional Autónoma de México. Researcher, Programa de Botánica, CPCA, Montecillo, México. e-mail: dahly@colpos.mx

 

Ramón Cuevas-Guzmán. Ph.D., CPCA, Montecillo, México. Professor-Researcher, Departamento de Ecología y Recursos Naturales, Centro Universitario de la Costa Sur, Universidad de Guadalajara. e-mail: rcuevas@cucsur.udg.mx

 

SUMMARY

 

Natural populations of Otatea acuminata (Munro) C.E. Calderón & Soderstr. subsp. aztecorum (McClure & E.W. Smith) R. Guzmán, Anaya & Santana-Michel were studied in the Sierra de Manantlán, Jalisco-Colima, in Western Mexico. The objectives were to compare the structure of otate populations at different harvesting levels, in order to evaluate the changes occurred due to management and to obtain the best prediction factor for culm production. Forty-one 50m2 plots were randomly established in harvested and non-harvested stands, and were observed over a 2 year period. There was no significant difference between harvested and unharvested stands, but the latter had higher densities and longer stems on average. Culm diameter and height were significantly different according to soil type in a nonparametric ANOVA. A backward lineal regression analysis identified a prediction model for juvenile culms production. Present exploitation levels by artesans appear to be sustainable.

 

KEYWORDS: Bamboo Harvest; Non-wood Forest Product; Otatea; Tropical Deciduous Forest; Western Mexico 

 

RESUMEN

 

Se estudiaron poblaciones naturales de Otatea acuminata (Munro) C.E. Calderón & Soderstr. subsp. aztecorum (McClure & E.W. Smith) R. Guzmán, Anaya & Santana-Michel en la Sierra de Manantlán, Jalisco-Colima, en el occidente de México. Los objetivos fueron comparar la estructura de las poblaciones con diferentes niveles de aprovechamiento, para evaluar los cambios debidos al manejo y obtener el mejor factor de predicción en la producción de tallos. Se establecieron 41 sitios de 50m2 y se observaron durante 2 años. No hubo diferencia significativa entre sitios cosechados o no, pero éstos últimos tuvieron, en promedio, mayores densidades y tallos más largos. El diámetro y altura de los tallos mostraron diferencias significativas de acuerdo con el tipo de suelo mediante un análisis de varianza no paramétrico. Un análisis de regresión lineal de retroceso identificó un modelo de predicción para la producción de tallos jóvenes. Los niveles actuales de explotación por artesanos parecen ser sostenibles.

 

RESUMO

 

Estudaram-se populações naturais de Otatea acuminata (Munro) C. E. Calderón & Soderstr. subsp. aztecorum (McClure & E. W. Smith) R. Guzmán, Anaya & Santana-Michel na Serra de Manantlán, Jalisco-Colima, no ocidente do México. Os objetivos foram comparar a estrutura das populações com diferentes níveis de aproveitamento, para avaliar as mudanças devido ao manuseio e obter o melhor fator de predição na produção de caules. Estabeleceram-se 41 lugares de 50 m2 e se observaram durante 2 anos. O diâmetro e altura dos caules mostraram diferenças significativas com o tipo de solo mediante uma análise de variância no paramétrico. Uma análise de regressão linear de retrocesso identificou um modelo de predição para a produção de caules jovens.

 

Received: 09/09/2003. Modified: 03/09/2004. Accepted: 03/16/2004.

 

 

Introduction

 

About 2.5 billion people worldwide use bamboo and there are 1250 known species with more than 1500 possible uses (FAO, 2000). Bamboos are primitive grasses that grow worldwide except in Europe, and nearly half of the species around the world are native to America, including woody and herbaceous bamboos. In Mexico the genera of woody bamboos with the widest distribution are Chusquea, Guadua, Olmeca and Otatea (Judziewicz et al., 1999).

 

One of the most common genera in Mexico is Otatea, a woody bamboo native to Mexico and Central America where it is called ‘otate’ (Guzmán et al., 1984). The name ‘otate’ means solid cane, and is derived from the nahuatl native language. This name is also used in some parts of Mexico for Rhipidocladum racemiflorum (Steudel) McClure, Guadua longifolia (E. Fourn.) R.W. Pohl, Guadua amplexifolia J. Presl (Santamaría, 1978) and Chusquea spp., as well as for some species of the genus Arundo, which is not a bamboo.

 

Otate is a semelparous plant with a 30 to 35 year life cycle, and it produces new shoots every year during the rainy season, from July to September (Vázquez-López et al., 2000). New, annual vegetative shoots reach their maximum size in 3- 4 months, and stop growing. At this time, they cannot be harvested. The first, second and sometimes third year culm, depending on environmental conditions, are recognized by local people as “new stem” but herein referred to as “juvenile”. These culms are selected for basket manufacturing because of their flexibility. Older culms (herein “mature”), usually more than 3 years old, are hard and are used as a construction material and for stakes in agriculture (Vázquez-López et al., 2000). About 7 to 8 years after emerging, the culms lose their consistency and become brittle and unhealthy. Afterwards, they die away, but new shoots replace them. When the flowering process is about to initiate, individuals stop producing new shoots and, also, every culm becomes brittle and unhealthy. After flowering all culms die away. During all the period of study, the Otatea acuminata stands in the area are flowering. Nevertheless, harvesting can continue because flowering is irregular in time and space. Flowering takes place in patches and some populations maintain vegetative propagation while others are in the sexual reproduction phase. The seedlings are fragile and highly sensitive to trampling and herbivory. The plants generated from seed (sexual propagation) reach their full size from 7 to 8 years after germination (Vázquez- López et al., 2000). Seeds may germinate in the same year they are produced.

 

Otatea forms dense thickets in tropical deciduous forests, called “otatales” (Santamaría, 1978). The tropical deciduous forest is noted for its high diversity, endemism and richness in useful species (Rzedowski, 1978; Benz et al., 1994; Cuevas- Guzmán et al., 1998). In the studied area Otatea acuminata subsp. aztecorum is one of the most abundant and useful species from this type of forest and it has been used for more than a century.

 

Deforestation rates in tropical deciduous forests in Mexico are high; the surface covered by this biome was reduced from 16 to 6% in 20 years (Flores et al., 1971; Lott et al., 1987; SARH, 1992, 1994; Mooney et al., 1995; Challenger, 1998; Trejo and Dirzo, 2000). Though data were obtained with different techniques and objectives, which makes it difficult to assess deforestation rates accurately, they give an idea of the extent of the loss of this vegetation type in the country. The main causes of deforestation are changes in land use, such as the introduction of grasses for extensive cattle grazing, as well as slash and burn agriculture (Miranda and Hernández, 1963; Rzedowski, 1978; Miller and Kauffman, 1998; Pennington and Sarukhán, 1998), timber extraction (Trejo and Dirzo, 2000) and repeated harvesting of useful species (Bye, 1995). This last factor, if done properly, also could be helping reduce deforestation, using it as a controlled harvest that could render enough benefits to the owners for avoiding land use changes.

 

The aim of this study is to compare the structure of otate populations at different harvesting levels, in order to evaluate the changes due to current harvest practices and to obtain the best prediction factor for culm production.

 

Methods

 

Study site

 

The study was carried out in the community of Platanarillo, in the northwestern region of the state of Colima, Western Mexico, between 19º21'16'' and 19º28'52''N, and 103º55'27'' and 104º01'09''W. It is located in the southeastern part of the Sierra de Manantlán, within the Sierra de Manantlán Biosphere Reserve, in a canyon with slopes ranging from 25 to 100% and altitudes from 900 to 1800m. The climate is midlatitude tropical sub-humid, according to the modified Köppen classification system (García, 1972), with a dry season Oct to May and a rainy season Jun to Sept, an average annual precipitation of 1350mm, and an average annual temperature of 22ºC (Martínez-Rivera et al., 1991). Most of the soils are derived from karstic limestone (Lazcano, 1988). These are Lithosols, which are rocky, shallow, and infertile soils. Regosols overlying igneous material occupy an important part of the area; these soils are deeper with less rocks and more organic matter (INEGISPP, 1981). Tropical deciduous forest covers the greatest portion of the study area. Here, otatales are an important component of the landscape and they occupy 800ha, according to satellite images (IMECBIO, 2000), even though only 300ha are accessible for harvesting.

 

Data collection

 

Forty-one 50m² (10 x 5m) plots were randomly established between 1997 and 1999 in harvested (19) and in nonharvested (22) areas. Every site was north-south oriented on its 10m side. Slope, rockiness, aspect and altitude were registered, as well as evidences of harvesting levels (number of stumps), fire, and grazing. Rockiness, fire, and grazing were determined according to Olvera-Vargas et al. (1996). Every culm was located, and their height and diameter at breast height (dbh) were measured within each plot. Three use categories and two health categories were recorded. Use categories were 1) “juvenile” referred to green culms, no more than 3 years old, with spiculate culm sheaths; 2) “mature” referred to green-yellowish culms with few culm sheaths; and 3) “overmature” or “dry” referred to completely yellow to grayish culms without culm sheaths nor foliage and with brittle stems. The limit of the potential life span of one culm seems to be 8 years. Health status was defined as 1) ‘healthy’ for green culms with complete foliage and regular internodes, or 2) ‘unhealthy’ for yellowish culms with scanty foliage and irregular internodes.

 

Data analysis

 

A nonparametric ANOVA was applied in order to find differences between sites using harvesting levels, grazing intensity and soil types as grouping variables. The Kruskal-Wallis test was applied using Wilcoxon scores (rank sum). Harvest levels were determined by the percentage of culms that were extracted: 0= Null (0%), 1= Low (10%), 2= Medium (20%), 3= High (>20%), and also simply as harvested vs non-harvested. The test was applied to density, height and dbh for every factor. Clustered error bars were calculated for density since it was the variable with the highest variation. The best prediction factor for culm production was identified with a backward linear regression analysis, using density of juvenile culms as the dependent variable. Data were analyzed with the SPSS program V. 10.0 (SPSS, 1999).

 

Results

 

Structural characteristics

 

For all the sites, variation of densities was greater than that of height and dbh (Table I), and in non-harvested sites variation was greater than that in harvested sites for juvenile and dry culms. Total density was not significantly different among harvesting levels (χ²=0.456, df=3, P=0.928), grazing intensity (χ²=0.776, df=2, P=0.679) or soil type (χ²=0.975, df=1, P=0.324). Densities of culms by use categories were also not significantly different among harvesting levels (juvenile culms: χ²=4.315, df=3, P=0.229; mature culms: χ²=1.0, df=3, P=0.810 and dry culms: χ²=4.436, df=3, P=0.218), grazing intensity (juvenile culms: χ²=2.652, df=2, P=0.266; mature culms: χ²=0.425, df=2, P=0.808 and dry culms: χ²=1.832, df=2, P=0.4), nor soil types (juvenile culms: χ²=0.0, df=1, P=0.988; mature culms: χ²=1.517, df=1, P=0.218 and dry culms: χ²=1.170, df=1, P=0.279). However, the average densities of juvenile and mature culms were consistently higher in harvested stands (Table I).

 

Comparison of dbh and height did not show significant differences among harvesting levels (juvenile culms dbh: χ²=1.153, df=3, P=0.764; mature culms dbh: χ²=4.387, df=3, P=0.223 and dry culms dbh: χ²=2.958, df=3, P=0.398; juvenile culms height: χ²=0.718, df=3, P=0.869; mature culms height: χ²=4.954, df=3, P=0.175 and dry culms height: χ²=1.771, df=3, P=0.621); or grazing intensity (juvenile culms dbh: χ²=0.626, df=2, P=0.731; mature culms dbh: χ²=3.187, df=2, P=0.203 and dry culms dbh: χ²=2.479, df=2, P=0.289; juvenile culms height: χ²=3.052, df=2, P=0.217; mature culms height: χ²=5.829, df=2, P=0.054 and dry culms height: χ²=2.684, df=2, P=0.261), but rendered significant differences between soil types (juvenile culms dbh: χ²=5.980, df=1, P=0.014, mature culms dbh: χ²=11.874, df=1, P=0.001 and dry culms dbh: χ²=11.671, df=1, P=0.001; juvenile culms height: χ²=3.66, df=1, P=0.056; mature culms height: χ²=7.138, df=1, P=0.008 and dry culms height: χ²=3.21, df=1, P=0.073). Greatest dimensions were observed in harvested sites (Table I), and the longest culms were found in regosols.

 

Total density appears to be the best descriptor for the effects of harvesting. We used clustered error bar graphics (confidence interval 95%) to demonstrate differences within the two-year period. There is a considerable change in densities of juvenile and dry culms. Recruitment in 1997 was higher than mortality, whereas in 1999 recruitment decreased and mortality increased (Figure 1). Figures 2 and 3 show this variation in recruitment and mortality broken down by management type. The non-harvested stands show a lower density of mature culms and a higher mortality than harvested ones.

 

 

 

 

 

 

 

Harvesting intensity and prediction of shoot production

 

Stump density indicated a reduction in harvesting level (Figure 4); in 1997, 32% of the juvenile culms were harvested, whereas in 1999 only 9% were. As harvesting levels decreased in the studied otatales, the number of healthy culms decreased too. Dry and unhealthy culms increased from 1997 to 1999 (Table II). Linear backward regression analysis identified density of mature culms as the best predictor for shoot production (Figure 5): y= 0.1942x + 458.679, where y: density of juvenile culms and x: density of mature culms; N=41, R²=0.396, F=25.578 (P<0.05), t=5.057 (P<0.05).

 

Discussion

 

Although not significant, data suggest that harvesting increases shoot production (Table I; Figure 4), stimulates growth of rhizomes and roots, and perhaps storage of nutrients. This could be interpreted as compensatory growth (McNaughton, 1983), which increases net primary productivity after harvesting or grazing in many plant species as a result of an increment in relative growth rates of shoots (Olson and Richards, 1988).

 

Significant differences were found for populations growing on different soils; deeper soils predictably had lasger otates. However, mean differences were too small (0.12m in height and 0.14cm in dbh, see Table I) to influence harvesting. Yet, culms were slightly larger in harvested sites. These sites had the highest densities of juvenile and mature culms and the lowest density of dry culms (Figure 3). Similar results were reported by Vázquez-López et al. (2000) using a different sampling method and data analysis.

 

Under a traditional management system of otatales in the study area there is no planned selection of areas for harvesting. The main criteria for choosing a harvesting site are accessibility and proximity to villages. In practice, there are two additional factors that restrict harvesting and affect the populations. First, recent delimitation of individual land property in communal lands due to new property rights oblige artisans to look for new harvesting zones. Second, a sequential prolonged flowering process from 1993 onwards has diminished the stock of useful otate culms. Before flowering the culms become brittle and unhealthy and have several holes, 3-4.5mm in diameter, likely caused by some Curculionidae species observed in the field that are used afterwards as nests by wasps, probably from the worldwide distributed genus Psenulus (Matthews, 2000). Thus, these otatales are no longer useful for basketry nor as stakes. However, even in stands with imminent flowering annual harvesting was lower than recruitment in both years of the study. This suggests that traditional harvesting has been done at a conservative level and does not deteriorate the resource.

 

This study showed that mature culm density is the best predictor for culm production. This indicates that juvenile culm production is a function of the number of mature culms nearby, though an excess of mature culm limited re-sprouting (Vázquez-López et al., 2000) and recruitment decreased as density increased. This effect may be due to an intraclonal regulation of the new shoot natality or even self-thinning by mortality of genets (Makita, 1996). Similar results were obtained by Taylor and Qin (1993) in China. In Colombia, most “guaduales” (Gua dua’s populations) without management had high proportions of mature and dry guaduas and few juvenile culms (Cruz, 1994). Similar tendencies were encountered by Christanty et al. (1996) in an agroforestry management system in a humid tropical region in Indonesia, as well as by Singh and Singh (1999) in an experimental bamboo plantation in a dry tropical region in India.

 

Otate’s potential production is considerable. For example, Pemphreon a stand with a density of 5000 mature otate culms/ha we predict a production of ca. 1430 juvenile culms/ha/yr. Every juvenile culm has an average weight of 5 to 6kg. Therefore, the results predict an estimated yield of 7 to 8tons/ha of bamboo fresh weight. Besides, mature culms can be sold as stakes at a price of US$0.10 to US$0.20 each. The bamboos not only provide income to peasant families, but also play an important role in regenerating the forest, restoring and maintaining fertility and the productivity of land, conserving soil moisture and reducing and preventing erosion and flood risks, as well as replacing unsustainable agricultural production activities (Christanty et al., 1996; Singh and Singh, 1999; Ruiz-Pérez et al., 2001).

 

Finally, grazing livestock break juvenile culms, eat the apical part of the new shoot, trample and graze seedlings completely. Stands that flower must remain undisturbed for at least 3 to 4 years to avoid damage to seedlings. However, cattle owners consider these recuperating stands an attractive range and introduce livestock. According to local people, this practice has already completely destroyed numerous stands. The control efforts should be directed towards integral management plans to avoid the deterioration of the otatales.

 

 

ACKNOWLEDGEMENTS

 

The authors are thankful to the otate artisans and land owners of Platanarillo, particularly Juan Enciso and Pedro Figueroa for information and logistic support, to Miguel Olvera and Blanca Figueroa for helpful comments, to Manuel Pio Rosales for the statistical analyses. Pia Winland and Cyntia Ayala improved the final document.

 

REFERENCES

 

1. Benz BF, Santana FJ, Pineda MR, Cevallos J, Robles L, De Niz D (1994) Characterization of mestizo plant use in the Sierra de Manantlán, Jalisco-Colima, México. J. Ethnobiol. 14: 23-41.        [ Links ]

 

2. Bye R (1995) Ethnobotany of the Mexican tropical dry forests. In   Bullock  SH, Mooney  H, Medina  E (Eds.) Seasonally Dry Tropical Forests. Cambridge University Press: Cambridge, UK. pp. 423- 438.        [ Links ]

 

3. Challenger  A (1998) Utilización y conservación de los ecosistemas terrestres de México. Pasado, presente y futuro. Comisión Nacional para el Conocimiento y Uso de la Biodiversidad. Instituto de Biología. Universidad Nacional Autónoma de México. 847  pp.        [ Links ]

 

4. Christanty L, Mailly D, Kimmins JP (1996) “Without bamboo, the land dies”: Biomass, litterfall, and soil organic matter dynamics of a Javanese bamboo talunkebun system. Forest Ecol. Manag  87: 75-88.        [ Links ]

 

5. Cruz H (1994) La Guadua  nuestro bambú. Centro Nacional para el Estudio del Bambú Guadua: Armenia, Colombia. 293 pp.        [ Links ]

 

6. Cuevas-Guzmán R, Núñez-López NM, Guzmán-Hernández L, Santana-Michel FJ (1998) El bosque tropical caducifolio en la reserva de la biosfera Sierra de Manantlán Jalisco-Colima  México. Boletín del Instituto de Botánica( Universidad de Guadalajara)  5: 445-491.        [ Links ]

 

7. FAO  (2000) Information bulletin on non-wood forest products. Non- Wood News, Nº7. Food and Agriculture Organization: Rome, Italy. 95 pp.        [ Links ]

 

8. Flores MG, Jiménez J, Madrigal X, Moncayo F, Takaki F (1971) Tipos de vegetación de la República Mexicana. Subsecretaría de Planeación, Dirección General de Estudios, Secretaría de Recursos Hidráulicos: México, DF. 135 pp.        [ Links ]

 

9. García E (1972) Modificaciones al sistema de clasificación climática de Köeppen. Instituto de Geografía. Universidad Nacional Autónoma de México: DF, México. 217 pp.        [ Links ]

 

10. Guzmán R, Anaya MC, Santana -Michel  FJ (1984) El Género Otatea (Bambusoideae) en México y Centroamérica. Boletín del Instituto de Botánica (Universidad de Guadalajara) 5: 2-20.        [ Links ]

 

11. IMECBIO  ( 2000) Diagnóstico integral y plan de manejo de los recursos naturales: Ejido Platanarillo, Municipio de Minatitlán, Colima. Instituto Manantlán de Ecología y Conservación de la Biodiversidad. Universidad de Guadalajara. Autlán de Navarro, Jalisco. México. 125  pp.        [ Links ]

 

12. INEGI-SPP   ( 1981) Síntesis Geográfica del Estado de Colima. Coordinación General de los Servicios de Estadística, Geografía e Informática: México, DF. 133 pp.        [ Links ]

 

13. Judziewicz EJ, Clark LG, Londoño X, Stern MJ (1999) American bamboos. Smithsonian Institution Press: Washington DC, USA. 392 pp.        [ Links ]

 

14. Lazcano C (1988) Las cavernas de Cerro Grande, Estados de Jalisco y Colima. Laboratorio Natural Las Joyas. Universidad de Guadalajara: Guadalajara, México. 144 pp.        [ Links ]

 

15. Lott EJ, Bullock SH, Solís-Magallanes JA (1987) Floristic diversity and structure of upland and arroyo forest of Coastal Jalisco. Biotropica 19: 228-235.        [ Links ]

 

16. Makita A (1996) Density regulation during the regeneration of two monocarpic bamboos: self-thinning or intraclonal regulation?. J.Veg.Sci 7: 281-288.        [ Links ]

 

17. Martínez-Rivera LM, Sandoval JJ, Guevara RD (1991) El clima en la reserva de la biosfera Sierra de Manantlán (Jalisco-Colima, México) y en su área de influencia. Agrociencia 2: 107-119.        [ Links ]

 

18. Matthews RW (2000) Nesting biology of the stem nesting wasp Psenulus interstitialis Cameron (Hymenoptera: Crabronidae: Pemphredoninae) on Magnetic Island, Queensland. Austral.J.Ent. 39: 25-28.        [ Links ]

 

19. McNaughton SJ (1983) Compensatory plant growth as a response to herbivory. Oikos 40: 329-336.        [ Links ]

 

20. Miller PM, Kauffman JB (1998) Effects of slash and burn agriculture on species abundance and composition of a tropical deciduous forest. Forest Ecol.Manag. 103: 191-201.        [ Links ]

 

21. Miranda F, Hernández E (1963) Los tipos de vegetación de México y su clasificación. Bol.Soc.Bot.Méx. 28: 29-179.        [ Links ]

 

22. Mooney HA, Bullock SH, Medina F (1995) Introduction: In  Bullock  SH, Mooney  HA, Medina  E (Eds.) Seasonally Dry Tropical Forests. Cambridge University Press: Cambridge, UK. pp. 1-7.        [ Links ]

 

23. Olson  BE  and  Richards  JH (1988) Tussock regrowth after grazing: intercalary meristem and axillary bud activity of tillers of Agropyron desertorum. Oikos 51: 364- 382.        [ Links ]

 

24. Olvera-Vargas M, Moreno S, Figueroa- Rangel BL (1996) Sitios permanentes para la investigación silvícola. Manual para su establecimiento: Libros Técnicos del Instituto Manantlán. Universidad de Guadalajara: Guadalajara, México. 55 pp.        [ Links ]

 

25. Pennington TD, Sarukhán J (1998) Árboles tropicales de México. Manual para la identificación de las principales especies. 2nd ed. Fondo de Cultura Económica: México, DF. 521 pp.        [ Links ]

 

26. Ruiz-Pérez M, Fu M, Yang X, Belcher B (2001) Bamboo forestry in China. J.For. 99: 14-20.        [ Links ]

 

27. Rzedowski J (1978) Vegetación de México. Limusa: DF, México. 432 pp.        [ Links ]

 

28. Santamaría FJ (1978) Diccionario de mejicanismos. 3rd ed. Porrúa: México, DF. 776 pp.        [ Links ]

 

29. SARH  (1992) Inventario Nacional Forestal de Gran Visión. México, DF. 120 pp.        [ Links ]

 

30. SARH  (1994) Inventario Nacional Forestal Periódico. México, DF. 114 pp.        [ Links ]

 

31. Singh AN, Singh JS (1999) Biomass, net primary production and impact of bamboo plantation on soil redevelopment in a dry tropical region. Forest.Ecol.Manag. 119: 195-207.        [ Links ]

 

32. SPSS (1999) SPSS Program for Windows Release. Version 10.0. SPSS Inc. 32. Chicago, IL, USA  Taylor. AH, Qin Z (1993) Structure and dynamics of bamboos in the Wolong Reserve, China. Am.J.Bot. 80: 375-384.        [ Links ]

 

33. Trejo I, Dirzo R (2000) Deforestation of seasonally dry tropical forest: a national and local analysis in México. Biol.Cons. 94: 133-142.        [ Links ]

 

34. Vázquez-López. JM, Benz BF, Olvera-Vargas M, Graf S (2000) Structure of populations of otate (Otatea acuminata subsp.aztecorum:Poaceae) in harvested stands. Sida 19: 301-310.         [ Links ]