Tamaulipan Thornscrub Research Articles

Qualitative and Quantitative Characterization of Wood Fibers of Shrubs and Tree Species of the Tamaulipan Thorn Scrub, Northeastern Mexico and Its Possible Relation to Wood Quality and Utilization

The present study was undertaken to determine the variability in fiber cell morphology and its length among wood species of the Tamaulipan Thorn Scrub, Northeastern Mexico, used for various uses such as timber for furniture, fence, post, firewood and sources of forage. The results reveal large variability in fiber cell morphology and fiber cell dimensions. The species are classified on the basis of its fiber cell morphology and fiber cell length and recommended for their possible utilization for different purposes. Wood having fibre cells with broad lumen and thin wall could be suitable for the manufacture of paper documented in the literature viz. Acacia farnesciana, Caesalpinia mexicana, Cordia boisiieri, Diospyros palmeri, Forestieria angustifolia, Morus celtifolia, Prosopis laevigata. This technique can be used in preliminary screening of woody species for its utilization for different purposes. Further studies are needed to confirm.

Woody Plants of Tamaulipan Thorn Scrub: Morphology, Wood Anatomy and Ecophysiology

During last three to four years we studied various aspects of woody plant species in Forest Science School, Universidad de Nuevo Leon, UANL, Mexico. The present study describes salient characteristics of habitat, leaf morphology, wood anatomy, wood density and few eco-physiological traits of major woody plant species of Tamaulipan Thornscrub, at Linares, Northeastern Mexico. This will serve as guide to know about all these traits for the students, researchers and foresters to unveil the various aspects of these woody species of high economic importance and ecological importance.

Variability in Wood Density and Wood Fibre Characterization of Woody Species and Their Possible Utility in Northeastern Mexico

Context: Preliminary screening has been undertaken by woody species of Tamaulipan thornscrub for wood density and its utilization northeastern Mexico for different purposes and to find possible relationship of density with wood fibre characteristics. This technique can be used in the selection of species with high wood density for possible utility. Aims: It is to determine the variability in wood density and in fiber cell morphology and its length and among wood species of the Tamaulipan thornscrub, northeastern Mexico. Methods: Wood density and wood fibres are characterized in these woody species following standard methodology. Results: The results reveal large variability in wood density and in fibre cell morphology h. The species have been classified on the basis of wood density and its fibber cell morphology and has been recommended for their possible utilization for different purposes. Conclusions: Species desirable for strong furniture making, paper pulp, soft furniture, fence etc. can be selected on the basis of fibre length to breadth ratios as strong fibres for furniture and fibre cells with broad lumen and thin cell wall use for fabrication of paper pulp and other utilities.

Composition, structure and diversity of shrublands in central Nuevo Leon, Mexico

The aim of this study was to carry out a comparative analysis at the plant community level of the five most common types of shrublands (semithorn shrubland, microphyllous desert shrubland, rosetophyllous desert shrubland, piedmont scrub, and tamaulipan thornscrub) in the state of Nuevo Leon (northeastern Mexico). Twenty-five sampling sites (100 m2 each one) were established in each shrubland type (25 in total) to evaluate the vegetation structure. At each sampling site, we estimated the plant density (N ha-1), plant coverage (m2 ha-1), specific richness ( S ), and alpha diversity index ( H’ ). One way-analysis of variance was used to compare plant attributes between the plant communities. In the studied five plant communities, a total of 85 vascular plant species were registered, belonging to approximately 65 genera and 28 families. The most representative families were Cactaceae (18 species), Fabaceae (16 species), Asteraceae (six species), and Agavaceae (five species). Analysis of variance showed highly significant differences between the shrublands in terms of the studied plant attributes. The microphyllous desert shrubland showed the lowest plant density (1,868 N ha-1) and plant coverage (2,637 m2 ha-1) and the piedmont scrub the highest (4,512 N ha-1 and 17,931 m2 ha-1, respectively). With respect to specific richness and the alpha diversity index, the lowest values ( S = 3.72 and H’ = 0.91, respectively) were presented by the microphyllous desert shrubland, whereas the semithorn shrubland exhibited the highest values ( S = 11.56 and H’ = 2.15). This study provides valuable information about the composition, structure and diversity of shrublands in the state of Nuevo Leon.

Characterization of Wood Fibres of Scrubs and Tree Species of the Tamaulipan Thornscrub, Northeastern Mexico and its Possible Utilization

The present study was undertaken to determine the variability in fiber cell morphology and its length among wood species of the Tamaulipan thornscrub, northeastern Mexico, used for various uses such as timber for furniture, fence, post, firewood and sources of forage. The results show large variability in fiber cell morphology and fiber cell length. The species have been classified on the basis of its fiber cell morphology and fiber cell length and recommended for their possible utilization for different purposes. This technique can be used in preliminary screening of woody species for its utilization for different purposes. Further studies are needed to confirm.

DINÁMICA DE LA CAPTURA DE CARBONO EN PASTIZALES ABANDONADOS DEL NORESTE DE MÉXICO

<p>Livestock activities due to the improper handling of the load capacity, suffer from low productivity in their grasslands, which are abandoned giving rise to the appearance of species considered invasive and undesirable for producers, without knowing the qualities of these as mitigating of climate change. The objective of the present study was to estimate the carbon content in tamaulipan thornscrub and three abandoned grasslands with a time of abandonment of 10, 20 and 30 years. For the estimation of the carbon content was used a systematic sampling design, in each area were established four sampling sites of 1,600 m<sup>2</sup>. The primary scrub is the system that resulted in the largest value of carbon content of 14.25 Mg ha<sup>-1</sup>, followed by the grasslands of 30, 20 and 10 years with 8.03, 7.33 and 4.13 Mg ha<sup>-1</sup> respectively. It was concluded that recovering the initial state of the primary scrub take many years, as can be seen in the grasslands system 30 years reaching only 56% of what it had in reserves of primary scrub.</p>

Deposition of Micro-elements through Leaf Fallen from Different Types of Vegetation, North-eastern Mexico

The aim of the study was to determine monthly (2007) the content and deposition of Cu, Fe, Mn and Zn in leaf fallen litterfall samples collected in four sites, northeastern Mexico. Site 1 was located at 1600 m of altitude in a pine forest, mixed with deciduous trees; site 2 was at 550 m in the ecotone of a Quercus spp. forest and submontane scrub; sites 3 and 4 (at 350 m and at 300 m, respectively) were located in the Tamaulipan Thornscrub vegetation. Leaf fallen litterfall samples at each site (2,500 m2) were obtained from ten canisters of 1.02 m that were randomly situated at each site. The Cu annual deposition (g ha-1 yr-1) was significantly different among sites being higher in site 4 (23.2) and lower in site 1 (4.1). Fe deposition was also significantly higher in site 4 (522.2) and lower in site 1 (120.0). Mn was higher in site 2 (479.4) and lower in site 1 (64.6). Zn was significantly higher in site 1 (62.8) and lower in site 1 (24.3). Micronutrient annual order deposition was as follows: Fe>Mn>Zn>Cu. Differences in deposition may be attributable to environmental conditions and plant species composition at each studied plant community.

Litterfall Production and Nutrient Deposition Through Leaf Fallen in three Tamaulipan Thornscrub Communities, North-eastern Mexico

Litterfall and the contents of macro- and micro-nutrients derived from its decomposition contribute greatly to the growth and productivity of forest ecosystem. The present study was undertaken to know the variability during two years in the deposition of litterfall and deposition of nutrients through leaf fallen litterfall in three sites of the state of Nuevo Leon (Los Ramones, China and Linares), north-eastern Mexico, which encompasses the Tamaulipan thornscrub plant community. The quantities of litterfall production and its constituents varied between 2009 and 2010, being the year 2010 where higher litterfall and nutrients occured. Mean litterfall production during the two years showed the following trend: Los Ramones (364.8), China (522.7) and Linares (583.1 g m-2 year-1). For leaf constituent, mean deposition ranged from 200.9 (Los Ramones) to 409.8 g m-2 year-1 (Linares), twigs from 62.4 (Los Ramones) to 89.3 (Linares), reproductive structures from 62.5 (Linares) to 80.3 (Los Ramones) and the miscellaneous component, constituted by unidentified plant material, body and insect feces, ranged from 21.1 (Linares) to 32.7 g m-2 year-1 (China). During the two years, mean annual deposition of Ca+K+Mg+P+N for Los Ramones, China and Linares was 10.1, 21.5 and 24.8 g m-2 year-1, respectively. Regardless of the research site, the order of macro and micro-nutrients deposition was as follows: Ca>N>K>Mg>P and Fe>Mn>Zn>Cu, respectively. There were spatial and temporal variations in litterfall deposition in terms of quantity, quality and potential nutrient returns. It is documented that the variability of litterfall and contents of nutrients derived from litterfall is influenced by the physioco-chemical characteristics of soils, diversity in vegetation and climatic conditions prevailing in different sites and years

Diversity-Productivity Relationship in the Northeastern Tamaulipan Thornscrub Forest of Mexico

This research examines the diversity-productivity relationship in a semiarid scrubland, initially under late successional conditions and subsequently under early successional conditions created by experimental clearing, to explore the roles that productivity and stochastic mortality play in species exclusion in this environment. A total of fifteen plots were studied by measuring environmental conditions and biomass components of shrubs and seedlings. These stands were distributed along a productivity gradient across five different landforms. A hypothesis about the stochastic self-thinning mortality model along the gradient was evaluated with the diversity-productivity-environment data. The diversity-productivity relationship was linear and reversed between the early and late succession stages. The hypothesis of stochastic mortality of species exclusion was rejected in the early stages of succession and partially accepted in the mature stage of succession. Species exclusion was negatively related to productivity gradients, suggesting that strong interspecific competition occurs in high productivity plots and that a larger number of species can survive in higher abiotic stress landscapes. Further research is needed to understand the temporal and spatial variations of the ecological interactions that shape this plant community.

Characterizing Regeneration of Woody Species in Areas with Different Land-History Tenure in the Tamaulipan Thornscrub, Mexico

Abstract The present study evaluated the regeneration of woody species in four abandoned areas with different land-history tenure (extensive production of livestock, intensive production of livestock, agriculture, and clearcutting) in the Tamaulipan thornscrub in northeastern Mexico. These areas regenerated naturally over a period of 21 years (1984–2005). These areas regenerated naturally over a period of 21 years (1984–2005). Four 250-m2 plots, each 10 × 25 m, were established in each area for sampling. At each plot, abundance, dominance, mean height of the tallest individuals, species richness, and diversity of the woody species were evaluated. To detect significant differences among the four areas, an analysis of variance (P 0.05). The area of intensive production of livestock showed the lowest ...

Trace elements in native shrubs consumed by white-tailed deer (Odocoileus virginianus) in northeastern Mexico

The contents of Cu, Fe, Mn, and Zn were seasonally determined in the leaves of the native shrubs – Castela erecta, Celtis pallida, Forestiera angustifolia, Lantana macropoda, and Zanthoxylum fagara – that are browsed by the white-tailed deer (Odocoileus virginianus). The study was conducted at the Tamaulipan thornscrub region, northeastern Mexico, between summer 2004 and spring 2006. Leaf tissues were collected from three county sites (China, Linares, and Los Ramones). Mineral contents were measured using an atomic absorption spectrophotometer. All minerals, in all plants, were significantly different among sites, seasons, and years, as well as the double and triple interactions. In general, plants at the Linares site, that had the highest rainfall, had higher trace element content. Moreover, during the second year, all plant species were higher in micromineral content. Furthermore, during summer were also higher. Regardless of spatiotemporal variations, all plants had suitable levels of Fe and Mn to satisfy the adult range of white-tailed deer requirements. The Cu and Zn presented marginal deficiency in some plants especially during dry seasons (winter and spring). Seasonal variations in minerals could be associated to soil water deficits, excessive irradiance during summer, and extreme low temperatures during winter and spring that could have affected leaf development and micromineral concentrations.

Análisis de la restauración pasiva post-pecuaria en el matorral espinoso tamaulipeco del noreste de México

La superficie con actividad ganadera en México es alrededor de 56 % del territorio nacional. El matorral es el ecosistema más distribuido e históricamente más utilizado para fines pecuarios en las zonas áridas y semiáridas de México. Para analizar la restauración pasiva postpecuaria en el matorral espinoso tamaulipeco del noreste de México se establecieron cuatro sitios de muestreo de 40 m x 40 m (1600 m2). En los sitios de muestreo se midieron todos los árboles y arbustos ≥3 cm de diámetro a 10 cm. Se utilizaron los indicadores ecológicos de abundancia, dominancia, frecuencia, índice de valor de importancia, índice de Margalef e índice de Shannon & Wiener. Se registraron dos especies dominantes (Vachellia farnesiana y Prosopis glandulosa) con el 74 % de la dominancia absoluta, mientras el 26% está dividido entre las 10 especies restantes. Se registró una abundancia absoluta de 3050 individuos, donde Vachellia farnesiana representa el 60 % del total. De acuerdo a la distribución diamétrica, se observó que de todos los individuos de Vachellia farnesiana, el 57 % (168 individuos) se encuentran en el rango de 0 cm a 10 cm de diámetro, lo cual indica que se está regenerado activamente.

Litterfall deposition and leaf litter nutrient return in different locations at Northeastern Mexico

The aim of this study was to determine the litterfall production and macronutrient (Ca, K, Mg, N, and P) deposition through leaf litter in four sites with different types of vegetation. Site one (Bosque Escuela) was located at 1600 m a.s.l. in a pine forest mixed with deciduous trees, second site (Crucitas at 550 m a.s.l.) in the ecotone of a Quercus spp. forest and the Tamaulipan thornscrub and third and fourth sites (Campus at 350 m a.s.l. and Cascajoso at 300 m a.s.l., respectively) were in the Tamaulipan thornscrub. Litter constituents (leaves, reproductive structures, twigs, and miscellaneous residues) were collected at 15-day intervals from December 21, 2006, throughout December 20, 2007. Collections were carried out in ten litter traps (1.0 × 1.0 m) randomly situated at each site of approximately 2,500 m2. Total annual litterfall deposition was 4407, 7397, 6304, and 6527 kg ha−1 y−1 for Bosque Escuela, Crucitas, Campus and Cascajoso, respectively. Of total annual litter production, leaves were higher varying from 74 (Bosque Escuela) to 86% (Cascajoso) followed by twigs from 4 (Cascajoso) to 14% (Crucitas), reproductive structures from 6 (Bosque Escuela) to 10% (Crucitas), and miscellaneous litterfall from N> K > Mg > P, whereas on site basis of total nutrient deposition (Ca + N + K + Mg + P), the order was Cascajoso > Campus > Crucitas > Bosque Escuela. Ca, K, Mg, N, and P nutrient use efficiency values in leaf litter were higher in Bosque Escuela, while lower figures were acquired in Cascajoso and Crucitas sites. It seems that the highest litterfall deposition was found in the ecotone of a Quercus spp. forest and the Tamaulipan thornscrub; however, the Tamaulipan thornscrub vegetation alone had better leaf litter nutrient return.

CONCENTRACIÓN DE CARBONO EN LA BIOMASA AÉREA DEL MATORRAL ESPINOSO TAMAULIPECO

The carbon concentration per unit of biomass (dry weight basis) was determined for 10 species in the Tamaulipan thornscrub and for each of their components (bole, branches, twigs, leaves and bark). Carbon concentration expressed as a percentage of biomass was obtained using a Solids TOC Analyzer, which determines the carbon concentration in solid samples by complete combustion. By ANOVA, no differences were found among the species in average carbon concentration (P>0.05). This concentration ranged from 44.25 to 47.08 % with an overall average of 45.4±1.32 %. Cordia boissieri (44.25±1.52 %) and Acacia farnesiana (44.52±1.37 %) are the species that had the lowest carbon concentration values, while Forestiera angustifolia (47.08±1.27 %) had the highest. The bark component of Cordia boissieri obtained the lowest carbon concentration percentage (39.62±0.70 %), while the leaves of Acacia schaffneri had the highest (50.14±1.21 %). The interaction of both factors was significant (P

Stemflow variation in Mexico’s northeastern forest communities: Its contribution to soil moisture content and aquifer recharge

► A comprehensive stemflow dataset was collected for two Mexico’s northern plant communities. ► For each species and for each stand, stemflow coefficients and infiltration depths are reported. ► Statistical stemflow differences are found between the species, plant communities and stands. ► Stemflow extrapolated threefold from trees to stands because of overstocked forests. ► Temperate forest stemflow appears to contribute to aquifer recharge because of shallow soils. Stemflow hydro-ecological importance was measured in trees and assessed in Mexico’s northeast forest stands by answering three basic questions: (a) what are the intra and inter-specific stemflow variations; (b) is the stemflow coefficient constant from tree level to stand scales? and (c) what is the stemflow area and wetted soil volume in individual trees and the stemflow volume discharged at the stand scale in two plant communities of northeastern Mexico? Gross rainfall and stemflow flux measurements were conducted on 78 trees of semi-arid, sub-tropical (31 Diospyros texana ; 14 Acacia rigidula ; four Bumelia celastrina ; five Condalia hookeri ; three Cordia bioissieri ; three Pithecellobium pallens ) and temperate forest communities (six Pinus pseudostrobus Lindl. and 12 Quercus spp.). Stemflow was extrapolated from individual trees to the stand scale using 98 inventory plots (1600 m 2 ha −1 each) placed in oak–pine forests and 37 quadrats (5 m × 5 m each) distributed across the Tamaulipan thornscrub forest range. Stemflow infiltration flux and infiltration area measurements assessed the wetted soil volume. Daily measurements were conducted from May of 1997 to November of 1998. Results showed that stemflow coefficients varied between plant communities since they averaged (confidence intervals, α = 0.05) 2.49% (0.57), 0.30% (0.09), and 0.77% (0.27) of the bulk precipitation for Tamaulipan thornscrub, pine, and oak forests, respectively. Intra-specific stemflow variations could not be identified in Tamaulipan although in temperate tree species. Basal diameter explained intra-specific stemflow variation in both plant communities. Stemflow increased threefold since it accounted for by 6.38% and 2.19% of the total bulk rainfall for Tamaulipan thornscrub quadrats and temperate oak–pine inventory plots, respectively. Small shrubs growing underneath large trees, in combination with the presence of small-diameter trees that recorded the largest stemflow coefficients appear to explain the increase of the stemflow coefficient from trees to stands. Stemflow replenishes soil moisture on the average 4.5 (1.4) times larger than does incident rainfall in open soils and appear to contribute to aquifer recharge in temperate forests due to a combination of shallow soils, high infiltration fluxes and the stemflow volume generated during rainfalls with depths >15 mm. Tracing studies should be conducted to test the hypothesis of the stemflow contribution to aquifer recharge in temperate forests of northeastern Mexico.

Community structure and floristic composition of Quercus fusiformis and Carya illinoinensis forests of the Northeastern Coastal Plain, Coahuila, Mexico

In order to describe community structure and richness in oak and walnut forests occurring along the San Rodrigo, San Diego, Escondido and Arroyo de las Vacas rivers on the Northeastern Coastal Plain (NE Coahuila, Mexico), we established 30 1 000-m2 circular plots, where we measured diameter at breast height (DBH) and tree heights. Tree regeneration and herb and shrub stratum were assessed in 5 2-m2 quadrats per site. A total of 48 species distributed in 29 families were recorded. Families with the largest richness were Poaceae, Asteraceae, and Malvaceae. For the oak forest, tree stratum density and basal area values were 386 stems/ha and 24.36 m2/ha, respectively, whereas for the walnut forest the corresponding values were 302 stems/ha and 21.26 m2/ha. The species with the highest relative importance values were Quercus fusiformis (59.48%) and Carya illinoinensis (57.58%). Total tree richness was 14 species, the most common ones being Celtis reticulata and Diospyros texana, followed closely by C. illinoinensis and Q. fusiformis. Anthropogenic impact appears to result in a poor regeneration reflected as a low sapling density, as well as in the reduction and fragmentation of these communities; in turn, this process has led to intrusions of species typical of the xerophytic Tamaulipan Thorn Scrub. Further studies are needed on the regeneration of the dominant species of these forests in order to describe their dynamics and to promote their preservation.

Effects of Plant Secondary Compounds on Nutritional Carrying Capacity Estimates of a Browsing Ungulate

Abstract Carrying capacity estimates based on digestible protein (DP) and energy (DE) are useful in comparing effects of land management practices or the ability of different vegetation communities to support herbivores. Plant secondary compounds that negatively affect forage quality would be expected to change nutritionally based estimates of carrying capacity. We evaluated the effect of plant secondary compounds on nutritionally based carrying capacity estimates of white-tailed deer ( Odocoileus virginianus Zimmerman) in Tamaulipan thorn scrub of northern Mexico. Forage biomass, nutrient concentration, and tannin concentration (protein-precipitating capacity) were measured for 23 forage items during spring and summer in three replicate pastures. Nitrogen in phenolic amines was estimated for the two principal woody browse species in deer diets and was assumed to be unavailable for amino acid synthesis. Carrying capacity estimates were calculated based on three dietary concentrations of DP and DE. Nutritional carrying capacity estimates that accounted for antinutritional compounds were reduced 50 ± 6%, 28 ± 8%, and 0 ± 0% (mean ± SE) for diets of high, medium, and low DE concentration, respectively, compared to estimates from models that ignored the effects of these compounds. Accounting for effects of plant secondary compounds reduced DP-derived carrying capacity estimates 4 ± 3%, 47 ± 9%, and 9 ± 8% for diets with high, medium, and low concentrations of DP, respectively. High variation in percent reduction in carrying capacity estimates occurred because of site and seasonal variation in plant species composition and biomass, making application of a single correction factor to account for plant secondary compound effects on carrying capacity infeasible. Protein-precipitating capacity of tannins accounted for > 98% of the reductions in carrying capacity estimates based on DP. Our results clearly demonstrate the need to consider effects of tannins on ungulate carrying capacity estimates based on DP and DE. Estimates can be further refined by accounting for nonprotein nitrogen and other antinutritional compounds in all forage items.

Diabolic Caminos in the Desert and Cat Fights on the Río: A Posthumanist Political Ecology of Boundary Enforcement in the United States–Mexico Borderlands

This article makes the case for addressing nonhumans as actors in geopolitical processes such as boundary making and enforcement. The challenge of this line of argumentation is to account for nonhumans as actors without enacting dualistic ontologies that locate the natural and social in separate realms. To address this methodological challenge, I present a posthumanist political ecology. I elaborate my argument and methodological approach in relation to my research on the environmental dimensions of U.S. border security. Specifically, I examine how deserts, rivers, Tamaulipan Thornscrub, and cats inflect, disrupt, and obstruct the daily practices of boundary enforcement, leading state actors to call for more funding, infrastructure, boots on the ground, and surveillance technology. As my research illustrates, taking nonhumans seriously as actors alters explanations for the escalation of U.S. enforcement strategies.

Status and habitat requirements of Physaria thamnophila, an endangered species of Tamaulipan thornscrub

Abstract Physaria (Lesquerella) thamnophila (Brassicaceae; henceforth Physaria) is an endangered herbaceous perennial plant of remnant patches of Tamaulipan thornscrub near the southern Texas border. Six years of censuses of four populations of Physaria were analyzed. Quantitative data were collected to describe the plant community in the four sites. There was no overall trend in population size, but fluctuations in observed numbers of plants among years were extremely large: a single census cannot provide a reliable assessment of a population of this species. Seedling numbers were positively related with shrub canopy cover. However, there were many more Physaria plants in the brush-cleared portion of one site than in its uncleared portion. Seedling survival may be facilitated by anything that reduces movement of the highly erodible soils of these sites.

Status and habitat requirements of Physaria thamnophila, an endangered species of Tamaulipan thornscrub

Status and habitat requirements of Physaria thamnophila, an endangered species of Tamaulipan thornscrub