Plant resources of the Tehuacán-Cuicatlán valley, Mexico

Information on richness of plant resources, and their forms of use and management in the biosphere reserve Tehuacan-Cuicatlan, Mexico is analyzed. This 10 000 km² region hosts nearly 2700 vascular plant species, and it is acknowledged as one of the arid areas with the highest floristic diversity in North America. The seven indigenous ethnic groups that live in this region have cultural roots that date back almost 10 000 years. Based upon ethnobotanical and floristic studies, as well as bibliographical sources, a total of 808 useful plant species were identified, most of them (90%) being native, and 44 species being endemic to the region. A total of 681 species are wild plants, 109 are weeds and ruderal plants, and 86 are domesticated crops. However, it was noted that considerable overlap exists between the species of these 3 categories. For example, while wild and ruderal plants (706 species) are foraged by both humans and domestic animals, 59 species of this group are also managed in situ. On the other hand, 168 wild, ruderal and domesticated species are cultivated. The Tehuacán-Cuicatlan Valley is one of the richest regions of Mexico in plant resources. Local knowledge on use and management of plants is a valuable source of information for designing conservation and social development strategies for the biosphere reserve.     

Plant Management in the Tehuacán-Cuicatlán Valley, Mexico1

Plant Management in the Tehuacán-Cuicatlán Valley, Mexico. Plant management types currently practiced in the Tehuacán-Cuicatlán Valley, México, were documented and analyzed based on ethnobotanical studies conducted in 13 villages with six indigenous groups and Mestizo people. The information was organized in a data base, and then detailed and guided to a consensus through six workshops carried out by ethnobotanists working in the area. From a total of 1,608 useful plant species, we identified 610 with at least one management type other than simple gathering. Managed species are mainly used as food, fodder, medicinal, and ornamental, and they belong to 101 plant families. The higher species numbers were recorded in Cactaceae, Asteraceae, Fabaceae, Crassulaceae, and Agavaceae. Nearly 60% of the managed species are native to the region and the rest are introduced from other regions of Mexico and the world. In total, 400 species are ex situ managed out of their natural environments through seed sowing and/or planting their vegetative propagules or entire young plants; 373 species are in situ managed in their natural habitats as follows: all these species are deliberately left standing during vegetation clearance, 76 species are also enhanced intentionally favoring their abundance through modifications of their habitat, or directly by planting their propagules, and 51 receive protection through regulations, particular strategies of extraction, and actions against herbivores, competitors, freezing, radiation, and drought. Most management forms involve artificial selection at different intensity levels. The information allows visualizing co-occurrence of incipient and advanced forms of management at different intensity levels within and among species, which helps to postulate testable hypotheses on factors influencing plant management and domestication in an important area for studying the origins of agriculture.     

Traditional Knowledge and Useful Plant Richness in the Tehuacán–Cuicatlán Valley,Mexico

Traditional Knowledge and Useful Plant Richness in the Tehuacán–Cuicatlán Valley, Mexico. This study systematizes ethnobotanical information about the interactions between people and plants, ethnofloristic richness, the relative importance of useful species richness in relation to general species richness, and plant management in the Tehuacán–Cuicatlán Valley of central Mexico. The study recorded a total of 1,605 useful vascular plant species (61.2% of the total species richness of the regional vascular flora), this being the region with the highest absolute richness of useful plant species in Mexico. The null hypothesis that plant families with a higher number of useful species would be those having a higher general species richness was analyzed through residuals method. The plant families richest in useful species were Poaceae, Asteraceae, Cactaceae, Cyperaceae, Mimosaceae, and Solanaceae, most of which also have the highest general floristic richness. However, analyses of use categories did not generally corroborate our hypothesis. About 1,335 of the useful species are wild, more than 500 species are submitted to some type of management (62 species are tolerated, 34 protected, 50 enhanced, and 358 cultivated), but only a few have been studied to document their process of domestication. This information can be useful for developing regional strategies of sustainable management of plant resources.     

Cofán Indians’ Monitoring of Freshwater Turtles in Zábalo,Ecuador

The Cofán Indians of Aguarico and Zábalo Rivers in Ecuador in 1990 began a turtle recuperation effort by raising turtle hatchlings (Podocnemis expansa and P. unifilis) in small pools. To evaluate the effectiveness of this program, the Cofán developed and tested three methods to document changes in the populations of turtles. The first method consisted of interviews with people from neighbouring communities about their perceptions of changes in turtle abundance. The second method was a direct count of turtles observed along the rivers from canoe. The third method was an indirect count, involving turtle nest censusing along community beaches. Two of the methods yielded numerical, statistically positive turtle population trends. The turtle program has influenced the community's perception of turtle conservation issues so that, instead of hunting the adults and eggs, they now protect them. The training in record-keeping permits them to make a transparent history of the equitability of access to the turtle egg resource. The Cofán monitoring experience strengthened their successful petition to the Ecuadorian government for the rights to manage their territorial lands within the Cuyabeno Wildlife Reserve, and to receive protected area status and management rights to other ancestral lands. The experience gained by the Zábalo monitors is now serving as a model for the design and implementation of the park monitoring system of the newly-established Cofán Park Ranger Corps, which will be patrolling three Ecuadorian Ecological Reserves which overlap Cofán inhabited areas.     

Temperature resistant Nocardia biovarieties in Tucumán,Argentina?

Eighty-six regional strains of the pathogenic Nocardia species isolated from soil and human mycetoma were tested for their response to different incubation temperatures and for their tolerance to different temperatures. The aim was to assess whether growth temperature and tolerance to elevated temperatures are valuable criteria for the differentiation of pathogenic species of local strains based on the results obtained from a large number of strains. The results showed that 75.34% of all N. brasiliensis isolates from both sources grew at a temperature higher than 37 °C. 20% of the mycetoma strains and 11.32% of those from soil grew at 45 °C. 98.1% of N. brasiliensis from soil and 55.0% of the mycetoma strains tolerated 50 °C for 8 h and many isolates from both sources endured this temperature for an even longer time and tolerated yet higher temperatures. Both properties (growth temperature and temperature tolerance) are used to identify N. asteroides complex (N. farcinica) and N. otitidiscaviarum, and according to our results they are not suitable to differentiate regional strains of this species. The N. asteroides strains assayed showed an ability to grow at and tolerate elevated temperatures superior to those belonging to the other species. Although adaptation of local N. asteroides and N. otitidiscaviarum strains to temperature is important, it is more significant for N. brasiliensis, because this species is predominant in the Tucumán soil and responsible for the major number of diseases in the area.This revised version was published online in October 2005 with corrections to the Cover Date.     

Space-time heterogeneities of the zooplankton distribution in La Concepción reservoir (Istán,Málaga; Spain)

Space-time distribution of the zooplankton (Rotifera, Cladocera and Copepoda) density along the central axis (horizontally and vertically) and the shores of La Concepción reservoir have been studied for one year. Results show that the distribution along the central axis and the shores follows similar patterns both in space and time. Rotifera and Copepoda mainly appear during the first part of the mixing period and Cladocera during stratification. Horizontal distribution is characterized by the occurrence of density gradients from the intake to the dam. Vertical distribution present density maximum at the Secchi depth during mixing and at two times Secchi depth, during stratification. Zooplankton distribution is related to physical-chemical and biotic factors.     

Ichthyofauna from wetlands of San Pedro, Balancán, Tabasco, México

San Pedro River's wetlands sustain trophic nets in the fluvial system, due to the high habitat availability, and space and temporal variations. In order to describe the relationship between environmental parameters and ichthyofauna, this study evaluated fish assemblages composition, distribution, abundance, density, biomass, richness species, diversity and equitability in the wetlands. Sampling considered three different sites and climatic seasons (dry, rainy and cold fronts). The physical and chemical parameters considered were dissolved oxygen, temperature, pH, water transparency and the depth. Fishes were caught with a shrimp net, after six minutes towings and were identified afterwards. A total of 1 049 organisms of 25 fish species were caught, two of which were exotic species: Oreochromis niloticus and Parachromis managuense. A total of 23 species were found at site I (with the highest density 0.23 ind./m2), 17 at site II (0.23 ind./m2) and 14 at site III (0.12 ind./m2). The dry season had the highest species number with 21 species, followed by the rainy season with 17 species, and the cold season with five species. Similarly, the highest biomass (8.30 g/m2) was found in dry season, followed by the rainy (2.16 g/m2) and the cold seasons (0.03 g/m2). Considering seasons, highest density was found during the dry (0.436 ind./m2), followed by the rainy (0.213 ind./m2) and the cold (0.023 ind./m2) seasons. The dominant density species during the study period, according to the quadrants graphic of Olmstead-Tukey were: Petenia splendida, Vieja heterospila, Vieja synspila, Dorosoma petenense and Astyanax aeneus. There were significant differences in the species richness among sites. Temperature, depth and transparency showed differences among the seasons. The canonical correspondence analysis indicated that fish distribution was governed by environmental parameters during all seasons. In terms of fish abundance and composition, environmental parameters play an important role showing spatial and temporal differences in the ecosystem, this could be explained with the fact that most of young fishes have a movement behavior to the wetlands, searching refuge and feed during the dry season. Considering the diversity indexes variation, it may be concluded that San Pedro River's wetlands correspond to a system where the ichthyofauna composition fluctuates spatial and seasonally.     

Plant management and biodiversity conservation in Náhuatl homegardens of the Tehuacán Valley,Mexico

Background

The Tehuacán Valley is one of the areas of Mesoamerica with the oldest history of plant management. Homegardens are among the most ancient management systems that currently provide economic benefits to people and are reservoirs of native biodiversity. Previous studies estimated that 30% of the plant richness of homegardens of the region are native plant species from wild populations. We studied in Náhuatl communities the proportion of native plant species maintained in homegardens, hypothesizing to find a proportion similar to that estimated at regional level, mainly plant resources maintained for edible, medicinal and ornamental purposes.

Methods

We analysed the composition of plant species of homegardens and their similarity with surrounding Cloud Forest (CF), Tropical Rainforest (TRF), Tropical Dry forest (TDF), and Thorn-Scrub Forest (TSF). We determined density, frequency and biomass of plant species composing homegardens and forests through vegetation sampling of a total of 30 homegardens and nine plots of forests, and documented ethnobotanical information on use, management, and economic benefits from plants maintained in homegardens.

Results

A total of 281 plant species was recorded with 12 use categories, 115 ornamental, 92 edible, and 50 medicinal plant species. We recorded 49.8 ± 23.2 (average ± S.D.) woody plant species (shrubs and trees) per homegarden. In total, 34% species are native to the Tehuacán Valley and nearly 16% are components of the surrounding forests. A total of 176 species were cultivated through seeds, vegetative propagules or transplanted entire individual plants, 71 tolerated, and 23 enhanced. The highest species richness and diversity were recorded in homegardens from the CF zone (199 species), followed by those from the TRF (157) and those from the TDF (141) zones.

Conclusion

Homegardens provide a high diversity of resources for subsistence of local households and significantly contribute to conservation of native biodiversity. The highest diversity was recorded in homegardens where the neighbouring forests had the least diversity, suggesting that management of homegardens aims at compensating scarcity of naturally available plant resources. Cultivated species were markedly more abundant than plants under other management forms. Diversity harboured and management techniques make homegardens keystones in strategies for regional biodiversity conservation.

     

Kármán vortex street detection by the lateral line

Fish use the lateral line system for prey detection, predator avoidance, schooling behavior, intraspecific communication and spatial orientation. In addition the lateral line may be important for station holding and for the detection of the hydrodynamic trails (vortex streets) generated by swimming fish. We investigated the responses of anterior lateral line nerve fibers of goldfish, Carassius auratus, to unidirectional water flow (10 cm s⁻¹) and to running water that contained a Kármán vortex street. Compared to still water conditions, both unidirectional water flow and Kármán vortex streets caused a similar increase in the discharge rate of anterior lateral line nerve fibers. If exposed to a Kármán vortex street, the amplitude of spike train frequency spectra increased at the vortex shedding frequency. This increase was especially pronounced if the fish intercepted the edge of a Kármán vortex street. Our data show that the vortex shedding frequency can be retrieved from the responses of anterior lateral line nerve fibers.     

Geospatial analysis of pollen records from the Yucatán peninsula, Mexico

Changes in distribution of semi-evergreen forest in the Yucatán peninsula and variation of precipitation during the late Holocene were inferred using a geographical information system. Deterministic methods for spatial interpolation using fossil pollen data from seven cores elucidated environmental changes. The changes in the distribution of the semi-evergreen forest allowed to us infer variations in precipitation in the area and to distinguish whether changes of forest cover are a consequence of climate and/or of human activities. The reconstruction of the Preclassic period (at 550 and 50 b.c.) indicates higher precipitation than at present and suggests a more closed vegetation cover. Around a.d. 450 the vegetation acquired an open character indicating a reduction in precipitation. During this time the decrease in forest was not homogeneous in the Yucatán peninsula, indicating human impacts in certain areas. A reduction in forest cover but not a complete deforestation of the region is assessed during the Classic period (a.d. 450). The reconstruction of a.d. 950 shows the recovery of the forest and is related to the Medieval warm period. Geographical information systems are useful tools to reconstruct the spatial history of the vegetation of the Yucatán peninsula during the late Holocene.     

Traditional knowledge and genetic diversity ofopuntia pilifera (cactaceae) in the tehuacán-cuicatlán valley, Mexico

Traditional Knowledge and Genetic Diversity of Opuntia pilifera (Cactaceae) in the Tehuacán-Cuicatlán Valley, Mexico. Economic Botany 59(4)366-376, 2005. Most studies of the genusOpuntia have focused on economically important species, and therefore more knowledge concerning the genetic diversity among wild and locally managedOpuntia species is needed for an expanded use of cacti in the future. The present study is part of ongoing ethnobotanical work in the Tehuacán-Cuicatlán Valley of Mexico and focuses on six traditionally classified forms ofOpuntia pilifera used as food by the indigenous Popoloca people in San Juan Atzingo. Traditional knowledge of how to distinguish these forms based on fruit flavor, color, size, and number of spines on the fruits and cladodes is preserved in the local community. Genetic fingerprinting with 129 AFLPs did not correlate with this traditional morphological classification of 67 cacti. Yet, these AFLPs distinguished the analyzed 67Opuntia pilifera cacti easily from the out-group comprising 17 wildOpuntia velutina.     

Proposal for the Establishment of the Core Zones in the Biosphere Reserve of Tehuacán-Cuicatlán, Mexico

This work proposes the establishment of core zones in the Biosphere Reserve of Tehuacán-Cuicatlán (BRTC), based on plant species richness and endemism. A total of 561 species of the four most important plant families in the region (Asteraceae, Cactaceae, Leguminosae and Poaceae) as well as 174 endemic species of these and other families were used in the analyses. Distribution of these taxa was analyzed using two different iterative complementarity methods. Significant correlations were found between patterns of species richness and endemic plants distribution in the study area. These results were combined with other analysis where two different indices (species richness index and human population index) were used. The results suggest the delimitation of four core zones within the Biosphere Reserve, covering a total area of 105,300 ha. The core zones represent 21.8% of the area, and would protect 72.54% of the species from the selected plant families and 67.8% of endemic species.     

Renegotiating gender and class in the berry fields of Michoacán,Mexico

This article examines the renegotiation of gender and class in a rural Mexican community where economic crisis in the sugar industry led foreign agribusinesses to promote blackberry and raspberry production for export and hire primarily women as berry pickers. Analysis focuses on the transition from a sugar economy where mostly men worked in the cane fields to non-traditional agricultural exports when women entered agricultural waged labor in unprecedented numbers. This restructuring of the regional economy raises important questions regarding the marginalization of differentiated subaltern groups and the nature of new sets of power relations between transnational agribusinesses, berry growers, and waged workers. I analyze the contradictions of this changing social field that connects Northern consumers, transnational company executives, berry growers, and waged laborers in a web of differential power relations as they reverberate along the commodity chain from campesino households to the global market.     

Canopy dieback in lower montane forests of Alto Urimán,Venezuelan Guayana

Canopy dieback in patches was discovered in an otherwise undisturbed very humid lower montane forest on a quartzitic sandstone plateau of the middle Caroní river basin, Venezuela. The patches vary in size from about 0.1 to 2 ha (50 to 700 upper story dead trees per ha). Preliminary inventories were carried out at 3 selected sites comparing 4 dieback patches (M) with adjacent not affected (V) forests. In the M plots, 40 to 61% of all trees with dbh 10 cm were dead. They consisted mostly (81–100%) of the endemic tree species Terminalia quintalata of the upper story (dbh > 20 to 60 cm, height up to 30 m), which is much sparser in the V stands. Data on stand structure and species composition are presented. They seem to indicate a spatial variation in the density of Terminalia quintalata, but also of other dominant species, and reproductive problems of Terminalia, which is hardly present in the diameter classes below 10 cm dbh. V and M stands grow on similar soils with a perched high water table. They are practically free of clay and rich in humus. The exchange complex is dominated by H⁺. Low pH and dilution of base cations represent the main chemical stress factors. Different concepts of the dieback process are discussed, including cyclic reproductive patterns, nutrient sequestering and drought frequency.     

Fishery of oceanic and coastal sharks in Colima, Jalisco and Michoacán

Shark fishery is one of the most important activities in the Mexican Pacific coast, nevertheless, there is few data available about the specific captures done by the fleet along the coast. This study describes fishery biology aspects of the shark species catched by the semi-industrial long-line fleet of Manzanillo. Monthly samplings were made on board of these vessels during an annual period from April 2006 to April 2007. Captured species composition (n = 1 962 organisms) was represented by nine species. The one that sustains this fishery was Carcharhinus falciformis (88.12%), followed by Prionace glauca (8.21%). Low frequency species were represented by Sphyrna zygaena (1.78%), Alopias pelagicus (0.82%), Carcharhinus longimanus (0.45%). Furthermore, rare species were Alopias superciliosus (0.35%), Carcharhinus leucas (0.1%), Carcharhinus limbatus (0.1%) and Isurus oxyrinchus (0.05%). Fishery activity affected principally (60-92.70%) young males of C. falciformis, S. zygaena, C. longimanus and I. oxyrinchus; adult males (56-75%) of A. pelagicus, A. superciliosus, and C. limbatus; for P. glauca there were primarily female adults. For all the species found, females showed the bigger sizes when compared to males (with the exception of S. zygaena, that showed sexual dimorphism). Considering the lineal regressions made between precaudal length and total length, and, fork length and total length for C. falciformis, P. glauca, S. zygaena and A. pelagicus, the determination coefficients (r2) showed that both lengths can be useful to obtain the total length of fish with some damage or absence of its caudal fin. The estimated fecundity for C. falciformis was of 3-7 offspring/female of 30-45 cm LT (average of 40.57 +/- 2.03 cm LT); and for P. glauca 5-52 offspring/female of 5-18.6 cm LT (average of 11.61 +/- 0.21 cm LT). In the case of C. longimanus only one female was captured with a total of eight embryos, with an average of 45 cm LT each; for this reason we assumed that the fishery areas do not coincide with the nursery oness for this species. According to the information obtained, we concluded that C. falciformis has a concurrent cycle and P. glauca a consecutive biannual one.     

What information do Kármán streets offer to flow sensing?

In this work, we focus on biomimetic lateral line sensing in Kármán vortex streets. After generating a Kármán street in a controlled environment, we examine the hydrodynamic images obtained with digital particle image velocimetry (DPIV). On the grounds that positioning in the flow and interaction with the vortices govern bio-inspired underwater locomotion, we inspect the fluid in the swimming robot frame of reference. We spatially subsample the flow field obtained using DPIV to emulate the local flow around the body. In particular, we look at various sensor configurations in order to reliably identify the vortex shedding frequency, wake wavelength and downstream flow speed. Moreover, we propose methods that differentiate between being in and out of the Kármán street with >70% accuracy, distinguish right from left with respect to Kármán vortex street centreline (>80%) and highlight when the sensor system enters the vortex formation zone (>75%). Finally, we present a method that estimates the relative position of a sensor array with respect to the vortex formation point within 15% error margin.