Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

A procedure for indirect measurement of tree height using clinometer is presented in this paper. The procedure allows avoiding the measurement of slope and horizontal distance between the observer and the objective tree. An experiment was designed to compare the proposed procedure with the traditional method in terms of time used for measurement and precision. The results from the experiment indicate that tree heights measured with the proposed method are better correlated with real tree heights than those obtained with the traditional method. The required time for measurement of a site using the proposed method is consistently, but not significantly lower than the time needed while using the traditional 3 method. It is concluded that the new procedure implies gains from the ergonomic, financial, and precision viewpoints during the development of forest inventory projects.

The Sontecomapan mangrove is located at Los Tuxtlas Biosphere Reserve, in the southern of Veracruz, Mexico. Currently, this area is listed in the Ramsar index with number 1342. Its biological, cultural and economical values are recognized. This ecosystem represents habitat, refuge, nesting area and nursery for numerous species. A distinctive characteristic of this mangrove is the high forest structure compared with other mangrove forests in Veracruz and as well as the high number of plants associated to this ecosystem, mainly epiphytes and orchids, many of them endangered. At the moment, their cultural value is underestimated, although the area of the swamp of Sontecomapan had relevance from the prehispanic time mainly by the Olmecan culture. Its economic value is as a food source and revenue for many people. However, several problems are affecting its conservation, such as the advance of human settlement on swamp land, illegal hunting, among others. This swamp constitutes a natural area protected administered by the Universidad Veracruzana. This paper described the initial strategy of preservation of this ecosystem, the formulation of a Management Plan. Investigation, education and conservation are the main objectives. 

The importance of mangrove systems as a source of income for coastal communities resides in their function as refuges and habitats for a great diversity of aquatic and terrestrial organisms. With the objective of developing a management plan for the Pampa-Murillo lagoon system, a model of the flow of matter inside and emanating from the mangrove was designed. The model was based on records of leaf litter production, herbivory, decomposition of fallen leaves and detritus movement towards the marine zone. Data was gathered from January to October in four types of mangrove forest where Rhizophora mangle, Laguncularia racemosa, Avicennia germinans and Conocarpus erectus species were present. In this system the daily production of leaf litter was 3,9 g/m2, equivalent to 7,9 t C/ha. The major leaf consumption by herbivores was in A. germinans with 13,6 %, followed of L. racemosa (12,5 %), R. mangle (9,8 %), being the lowest in C. erectus (5 ,7 %). The most resistant species to degradation was C. erectus which lost lower than 50 % of the initial organic matter content of its leaves over a period of 210 days. In contrast, A. germinans degraded most quickly retaining only 12,4 % of initial organic matter content after the same period. Of the organic matter produced by the forests, the mangrove system exports the least amount of detritus in May (0,5 t dry weigth/h), whereas detritus movement rises to 1,5 t/h (dry weight) in October. This represents the equivalent of approximately 4 822,2  t C/year, of which 54,5 % is organic matter. This material constitutes an important nutritional input into the adjacent marine zone.

The objective of this work was to restore 32 950 m2 of altered sites by means of sowing mangrove propagules and planting plantlets with the participation of the community. Two techniques were used for restoration: direct sowing of propagules collected from Rhizophora mangle, Laguncularia racemosa, and Avicennia germinans, and planting plantlets generated in recycled plastic bottles in a plant- nursery. Results were: 40 people participated, including women, men, elderly, and adolescents. A plant-nursery was constructed with 14 850 mangrove plants of the three species, using bottles collected from the waste dumps; on day 75, plants were taken to the field. In the nursery and field, a mortality of 3,4 % and 38,3 % was recorded in the R. Mangle plants; the growth rate was of 0,33 cm/day and 0,65 cm/day, and the height reached 97 cm and 156 cm in 204 days and 242 days. In L. racemosa, mortality increased to 50 % and 18 %, respectively, with a growth rate of 0,30 cm/day and 0,61 cm/day, reaching a height of 80 cm and 94 cm in 257 days. In A. germinans, mortality was high with 70,8 % and 24,3 % because the leaves were consumed by the caterpillar of the Junonia evarete butterfly, recording also the least growth rate with 0,23 cm/day, for a height of 94 cm in 264 days. At the end of the experiment, 40 034 plants were obtained of which 89 % corresponded to R. mangle.

An important zone of mangrove distribution in Yucatan is the Natural Protected Area Ría Celestún, located to the northwest of the Peninsula of Yucatan. The main impacts in this ecosystem are the interruption of water flows, uncontrolled urban growth, change in land use and deforestation. The soil of the region is karstic and highly permeable; as there are no rivers, the only source of water are the rainfall (760 mm year-1)  and groudwater discharges as springs, which have its greater influence in the inner zone of the lagoon, being reflected in the gradient of lower seawater salinity in the inner zone and higher seawater salinity in the mouth that connects with the Gulf of Mexico. Due to this gradient, different mangrove forest structure patterns, dominant species and productivity were observed, recording the higher forest structure and productivity values de 4,09 g m2 day-1 in the inner zone and of 2,59 m2 day-1 in the sea zone. The mangrove productivity in each zone of the lagoon is determined by climatic variability of the region (“nortes”, dry and rain seasons). The different structure patterns and litter production were determined by soil salinity and climatic condition. Therefore, the management strategies should consider the structure and natural behavior and the spatial and tempo-ral variability of the mangrove ecosystems, and their vulnerability in the hydrology and climate change.

Since 1960, when hurricane Adriana hit the region, no meteor had affected the coasts of Nayarit, in the Mexican Pacific. In October 1994, hurricane Rosa hit with winds of up to 160 km/h, affecting large mangrove areas. The most severe effects were exerted mainly on Laguncularia racemosa, followed by Avicennia germinans, and minimally on Rhizophora mangle. From the white mangrove, only 31,9 % of the trees remained standing with <10m of height and a DAP <10,8 cm. The largest effect of the hurricane was recorded in 39,9 % of the medium sized trees, which were bent and died later on. The oldest trees (28,1 %) were broken down by the force of the wind, due to the greater height (>11 m) and greater resistance because of the thickness of the trunks (>10,1 cm). In A. germinans, the biggest effect was recorded in the mature trees, since all of them suffered broken branches. In the whole lacunar system, L. racemosa presents a narrow and shallow radical system (90,7 and 30,9 cm) that makes it vulnerable to winds. The loss of wood due to the hurricane was variable: 35,0 m3/ha in the least affected site and up to 103,7 m3/ha in the mature forest. A large loss of propagules and plantules was also recorded in the forests. These events are frequent in the mangrove forests and can favor natural selection processes, which modulate succession and evolution of this vegetation along time. 

This work was aimed al assessing the decay resistance of acetylated Scots pine (Pinus sylvestris) sapwood against white (Corio/us versico/or) and brown (Coniophora puteana) rol fungí and the effect of pyridine as catalyst. Samples were decayed over pure cultures on 4% malt agar for twelve weeks, following the general procedures of the European Standard EN113. Additionally, the dimensional stabilityof wood given by acetylation was compared in the catalysed and uncatalysed chemical modification systems. The chemical modification provided resistance to the biodegradation ofthe wood against brown and white rol fungí. A greater leve! of acetylation was required to inhibit the brown rol, in comparison with the required leve! to preven! the white rol. The decay patterns and the weight loss recorded indicated that, pyridine as a catalyst did not influence the decay resistance of acetylated wood, when results werecompared within the same fungus species. The dimensional stability provided by acetilización, and measured by the antiswelling efficiency (ASE}, was satisfactory in both reaction systems, although the uncatalysed system was significantly more efficient. lt was concluded that the weight percentage gain due to chemical modification is a good indicator of the degree of permanent partía! swelling of the wood blocks, as well as of the dimensional stability and the resistance to decay of the acetylated wood. 

Buteogallus anthracinus is a tipically resident specie that create its nesting at the mangrove forest of Sontecomapan. This paper describes the nesting of B. anthracinus, evaluating size, composition vegetal of the nests and the specie host tree. In 2002 and 2003  by means of routes in boat and with special emphasis to sound emmission to six nests were located on mature trees were. It was found thah Rhizophora mangle, Laguncularia racemosa and Aviccenia germinans are used by B. anthracinus as host trees. The nests are oval in shape  with an average 38,5 cm of in diameter, 69,83 cm of external diameter and 52,5 cm in height. The center of the nest is constructed mainly withleaves of Avicennia germinans and the rest of Rhizophora mangle. It is discusses that the population of B. anthracinus can be dependent on the nest sites in this mangrove.

In order to consider the wood specific gravity of Pinus hartwegii in the La Malinche volcano two methods were used: the traditional one of the maximum moisture content (Smith, 1954) and the empirical method proposed recently (Valencia and Vargas, 1997); 22 small piecess wood were extracted with a Pressler dril!, to which both methods were applied. The average values, standard deviation, mínimum and maximum of the wood density were very similar. lt was determined that the specific gravity of the wood was 0,496 g/cm'. lt was demonstrated with a simple correlation that the results of both methods were very close to 1,0. The Pinus hartwegii wood is classified as moderately heavy. The specific gravity value obtained in this study can be u sed for biomass estimations of the wood from this species.

Several growth and increment in diameter, height and volume equations were fitted and validated for the pine species Pinus cooperi, P. durangensis, P. engelmannii, P. leiophylla and P. herrerae which naturally distribute in the region of El Salto, Durango, Mexico. The results showed that by using the Chapman-Richards equation the first pine species has the highest growth and increment estimated by two different approaches. This paper points out the need to establish permanent sampling plots to calibrate these technologies to be used in growth and yield modeling at the whole stand, size class or individual tree models.