Tamaulipan Thornscrub Research Articles

Factors Influencing the Faunal Recolonization of Restored Thornscrub Forest Habitats

Tamaulipan thornscrub forests (thornforests) have high ecological and economic values, yet over 90% of these forests have been lost, and they remain threatened, making them a conservation hotspot. For decades, federal, state, NGO, and corporate entities have been acquiring land and actively or passively restoring these forests, but results have been mixed and seldom monitored. This study characterized and quantified faunal communities of restored thornforest habitats in south Texas and examined the relationships between restored faunal communities and key site characteristics and environmental factors. We surveyed and analyzed mammal, bird, Lepidoptera, and herptile communities within 12 restored sites in the Lower Rio Grande Valley of southernmost Texas, USA. The site and environmental factors that influenced animal community composition, richness, diversity, and abundance varied widely among taxa. Time since restoration began and method of restoration influenced many community metrics, whereas patch size and extent of isolation influenced few. Several aspects of restored plant communities were influential, especially ground layer diversity, and high invasive plant cover negatively impacted many animal community metrics. If actively restoring a site, efforts to control invasive plants, foster native plant diversity, and provide a nearby water source are likely the most effective ways to promote faunal recolonization.

Ant Communities (Hymenoptera: Formicidae) in a Protected Urban Park in Northeast Mexico

Introduction: The creation of protected natural areas within urban environments has played an essential role in providing small reservoirs of native vegetation and refuges for endemic species. Objective: To analyze, through ant communities, the influence of urbanization in a protected natural area (PNA) located in an urban zone. Methods: From April to July 2022, using bait traps and pitfall traps along 100 m transects, the presence of ant species was recorded in the El Refugio State Park Natural Area in Tamaulipas, Mexico. Alpha diversity was assessed using Hill numbers, while beta diversity was evaluated using the Jaccard index. Additionally, indicator species were identified through the indicator value (IndVal). Multiple correspondence analysis was conducted to associate the presence of species with environmental variables and vegetation types, and contingency tables were created to relate ant presence to vegetation cover size. Results: Species richness and diversity decreased in sites with low vegetation cover, such as in Tamaulipan thornscrub; moreover, secondary vegetation retained greater species richness. Indicator species were found in secondary vegetation and grassland areas, mainly composed of species that tolerate high temperatures and generalists such as Forelius mccooki and Tetramorium spinosum, while lowland jungle species were the only indicator species. The presence of these species is primarily associated with temperature, humidity, and vegetation cover. A significant relationship between the presence of ant species and vegetation cover size in El Refugio State Park was evident. Conclusion: The structure and composition of ant communities vary according to the type of vegetation structure, particularly in areas that have undergone greater anthropogenic damage. Therefore, the conservation of landscapes, as well as monitoring of these areas, should be considered in future research. Keywords: green areas; formicids; conservation; indicator species; community ecology.

Impact of the perceived sensory dimensions of an atypical environment on perceived environmental restorativeness (Impacto de las dimensiones sensoriales percibidas de un ambiente atípico sobre la percepción de restauración ambiental)

ABSTRACT This study documents the restorative influence of an atypical natural environment characterized in terms of its ecosystem as Tamaulipan Thornscrub (TT), considering a classification of urban green areas based on eight perceived sensory dimensions (PSD). A sample of 444 university students (62% women; age range 18–29) evaluated the restorative potential of a set of images from the TT ecosystem classified in one of the following PSD categories: Diverse, Natural, Open, Cohesive, Social, Cultural, Sheltered and Serene. Analysis conducted using non-parametric repeated measures tests showed that Diverse and Serene PSD are significantly more restorative than the other dimensions, while Natural and Cohesive are the least restorative. The TT ecosystem overall was perceived to possess moderate global restorative potential. The interaction between PSD, the TT ecosystem, perceived environmental restorativeness and its contribution to the promotion of public health is discussed. Finally, the use of certain PSD in green areas is suggested along with the consideration of studying specific eco-biological factors.

Land abandonment as driver of woody vegetation dynamics in Tamaulipan thornscrub at Northeastern Mexico.

Vegetation structure is defined as the temporal and spatial distribution of plant species in a particular site. Vegetation structure includes vertical and horizontal distribution and has been widely used as an indicator of successional changes. Ecological succession plays an essential role in the determination of the mechanisms that structure plant communities under anthropogenic disturbances. After an anthropogenic disturbance, such as grazing, forests follow changes in the original composition and vegetation structure, which eventually could restore some of their attributes to become mature forests again. To know how the time of abandonment affects woody plant communities, we ask the following questions: (1) How does the species richness, diversity, and vertical structure (A index) change concerning the time of abandonment? (2) Are species similarities among woody vegetation communities determined by land abandonment? (3) Which woody species have the highest ecological importance in each successional stage? We explored how successional stages after land abandonment mediated the species richness, species diversity (alpha and beta), and ecological importance value index on four areas of Tamaulipan thornscrub. We selected four areas that differed in time of abandonment: 10, 20, 30, and >30 years. The first three areas were used for cattle grazing, whereas the >30-year area was selected as a control since it does not have a record of disturbance by cattle grazing or agriculture. During the summer of 2012, we randomly established four square plots (40 m × 40 m) in each area, separated at least 200 m from each other. In each plot, we recorded all woody individuals per species with a basal diameter ≥1 cm at 10 cm above ground level. We estimated species richness indices, species diversity (alpha and beta), and ecological importance value index. We recorded 27 woody species belonging to 23 genera and 15 families. Fabaceae accounted for 40% of the species. Acacia farnesiana was the most important and abundant species in the first three successional stages. We suggested that older successional stages of Tamaulipan thornscrub promote woody plant communities, characterized by a higher complex structure than younger communities. We observed the highest species similarity between the sites with a closer time of abandonment, while the lowest similarity was shown between the sites with extreme time of abandonment. We conclude that Tamaulipan thornscrub shows a similar trend of ecological succession to other dry forests and the time of abandonment has a high mediation on plant dynamics in the Tamaulipan thornscrub. Also, we stand out the importance of secondary forests for Tamaulipan thornscrub woody plant communities. Finally, we recommended future studies include aspects of regeneration speed, the proximity of mature vegetation, and the interactions of plants with their seed dispersers.

Ecogeographic Variation in Physical Traits of White-Tailed Deer

A growing body of work has revealed that differences in body size of ungulates follow ecoregion and soil boundaries and that these size differences are nutritionally influenced. Currently, it is unclear if these patterns of body size result from differences in quantity or quality of forage produced. We quantified differences in white-tailed deer (Odocoileus virginianus Zimm.) body mass and antler size captured at four sites in South Texas, United States. We sampled available forage to determine if long-term differences in average body and antler size could be explained by forage quantity or quality, or some combination of the two. Data collected from 2011 to 2019 indicated female body mass was > 3 kg smaller on the eastern edge of the Coastal Sand Plain ecoregion as compared with those from the western transition zone of the Coastal Sand Plain and Tamaulipan Thornscrub ecoregions. Similarly, male body mass and antler size were > 6 kg and > 20 cm smaller, respectively, in coastal habitats compared with more interior sites. We found that forb biomass, browse and forb diversity, and the nutritional landscape, quantified using digestible energy, crude protein, phosphorus, and neutral detergent fiber, differed between sites. However, differences between sites were inconsistent with predictions that would have supported our hypothesis. Overall, we found no support for the hypothesis that forage quantity drives ecogeographic variation in physical traits of white-tailed deer but were unable to fully refute or support the hypothesis that forage quality, specifically plant diversity, drives ecogeographic variation in physical traits of ungulates.

Litterfall and nutrient deposition in three forest Ecosystems, Northeastern Mexico

Litterfall contributes to the development of forest soils, since it undergoes a decomposition process that generates the release of nutrients ontothe soil. Therefore, the objective of this study was to evaluate the annual litterfall production, the return of nutrients (Ca, Mg, K and P) and thenutrient use efficiency (NUE) in three forest ecosystems of northeastern Mexico. Litterfall was quantified on a monthly basis from january todecember 2020 at three study sites: Site 1 Jesús María (Tamaulipan Thornscrub), Site 2 Crucitas (Submontane Scrub) and Site 3 BosqueEscuela (Pine-Oak Forest). Regarding the annual litterfall production (g·m⁻²·año⁻¹), the Crucitas site had the highest production (591.88) whilethe lowest one was registered at the Bosque Escuela site (466.77). Nutrient deposition (g·m⁻²·año⁻¹) varied as follows: Ca from 8.62 (BosqueEscuela) to 27.29 (Crucitas); Mg from 0.70 (Bosque Escuela) to 1.97 (Jesús María), K from 0.70 (Bosque Escuela) to 1.96 (Jesús María), andP from 0.19 (Bosque Escuela) to 0.51 (Crucitas). Regarding the NUE, Ca fluctuated from 21.68 (Crucitas) to 54.10 (Bosque Escuela), Mgfrom 253.43 (Jesús María) to 665.98 (Bosque Escuela), K from 64.16 (Jesús María) to 275.35 (Bosque Escuela), and P from 2413.3 (BosqueEscuela) to 1077.3 (Jesús María). The differences between litterfall production and nutrient deposition are due, in part, to the diversity ofspecies in each forest ecosystem, the phenology of the species and the environmental conditions prevailing at each study site.

Combined Effects of Scarification, Phytohormones, Stratification, and Soil Type on the Germination and/or Seedling Performance of Three Tamaulipan Thornscrub Forest Species.

Tamaulipan thornforests in south Texas and northeast Mexico are a conservation hotspot. Shortages of native seedlings limit regional restoration and are largely driven by knowledge gaps regarding propagation of the 75+ thornforest species planted during restorations. We previously investigated three thornforest species with low or inconsistent germination or seedling survival: Ebenopsis ebano (Fabaceae), Cordia boissieri (Boraginaceae), and Zanthoxylum fagara (Rutaceae), and identified the types and dosages of chemical seed treatments that maximized germination. However, chemical treatments were performed in isolation and combinational treatments may be required to break dormancy or maximize germination. This study builds on prior work by investigating the effects of all possible combinations of sulfuric acid (SA), gibberellic acid (GA), and indole-3-butyric acid (IBA) treatments on germination of the same focal species, and further quantified the combined effects of five chemical treatments, three stratification treatments, and six soil mixture types on the germination and seedling performance of the focal species. Ebenopsis ebano germination peaked with SA and was not improved with additional chemical treatments. Cordia boissieri germination was highest with GA only in our indoor experiment but peaked with GA + IBA + SA in our outdoor experiment. Zanthoxylum fagara germination was near zero in all treatments. Stratification treatments marginally reduced E. ebano germination and reduced C. boissieri seedling height. Soil type had significant impacts on E. ebano germination and leaf abundance (residual differences up to 40% or 4 leaves, respectively) and influenced some of the effects of chemical treatments. These results enhance our understanding of thornforest seed ecology and best practices for nursery propagation of seedlings.

EFFECTS OF DIFFERENT LAND-USE SYSTEMS ON SOIL PHYSICOCHEMICAL PROPERTIES OF A CHERNOZEM IN NORTHEAST MEXICO

<p class="Default"><strong>Background. </strong>The soil uses have been present since man domesticated the cultivated plants and, in the process, several changes in the soil’s physicochemical properties have been observed. Most of those changes have been detrimental to the soil’s productivity on a sustained basis. Thus, it is important to study and analyze the changes in soil’s physicochemical and hydraulic properties that get affections due to land conversion into different land-use systems. <strong>Objective. </strong>Assess the effect of different land-use systems on the physical, chemical, and hydrological properties of the soils in Northeast Mexico.<strong> Methodology. </strong>The study took place in a Chernozem soil in the Municipality of General Terán, Nuevo León, Mexico, and the land-use systems we investigated were: a citrus plantation, a grassland, an agricultural area, and the natural vegetation of the Tamaulipan Thornscrub site (MET) as a control treatment. Four composite soil samples were obtained from each site at two depths of 0-10 cm, and 10-30 cm, the chemical properties analyzed were pH and electrical conductivity (EC), and the physical properties consisted of Bulk density (BD), texture, total porosity (Tp), mechanical resistance to penetration (MRP) and field capacity (FC), permanent wilting point (PWP), available water (AW), initial infiltration (Ii), accumulated infiltration (Ai) and infiltration capacity (Ic). <strong>Results. </strong>The soil pH showed significant differences with depth (p=0.01), as well as the interaction of land-use depth (p=0.008), while electrical conductivity showed significant differences between land uses systems (p= 0.000); soil texture showed important differences in sand (p=0.003), silt (p=0.003) and clay content (p=0.006). There were significant differences between interaction of land-use soil depth, silt (p=0.003), and clay content (p=0.009). Soil hardness was significantly different between the diverse land-use systems (p=0.000). Concerning hydraulic properties, the water available in the place showed differences in land-use (p=0.001) and interaction land use-depth (p=0.006). Field capacity was also affected by land-use systems (p=0.000), as well as the interaction land use-depth (p=0.02); wilting point showed significant differences under distinct land use systems (p=0000), and in interaction of land use-depth (p=0003). <strong>Implications. </strong>More studies are needed in the short, medium and long term to monitor changes in physical, chemical, and water properties of soils under different land uses. Such information can be a guide in the proper management of these soils. <strong>Conclusion:</strong> From this study, it was possible to identify the negative impact that the different land-use systems have on the physical, chemical, and hydraulic properties of the soils under investigation. The hydraulic soil properties are the most affected.<strong> </strong>The information from this research can help for a better understanding of managing different land-use types in this Chernozem.<strong> </strong><strong><em></em></strong></p>

Distance sampling survey effort to improve density estimates of northern bobwhite

AbstractDistance sampling from aerial platforms can provide researchers with precise and efficient density estimates for wildlife populations, particularly over large areas. The intensity of the distance sampling survey depends on the survey effort. Effort can be referred to as coverage, where transect spacing is determined by the observer's sightability distance of the object or animal. Managers and researchers in Texas often use helicopters to survey and collect data for northern bobwhite (Colinus virginianus) density estimates. For bobwhites, 100% coverage represents transect spacing of 200 m, assuming observers can cover out to 100 m on either side of the transects. Often surveys are conducted at 50% coverage or 400 m spacing to reduce cost. Still, the implications of lowering survey effort on the precision of density estimates are unknown, particularly in coverage prescriptions. We flew 2,641 km of line transects each December from 2014 to 2017 and detected 2,333 bobwhite coveys across 7,648 ha of rangeland on the San Antonio Viejo Ranch in Jim Hogg County, TX, USA. We conducted line‐transect distance sampling from a helicopter platform at 50 and 100% coverage and simulated results at coverage <50% using empirical data. Based on the results of simulated surveys at <100% coverage, surveying for bobwhites using helicopters with less than 50% coverage results in variable density estimates (wide 95% confidence intervals) and low precision (coefficient of variation >20%). Empirical surveys conducted at 50 and 100% coverage show little variation in density estimates between the 2 levels of coverage. However, when broken into substrata (areas less than ~1,000 ha), conducting surveys at 50% coverage resulted in <60 detections, which led to low precision in density estimates (coefficient of variation >20%). Our results are based on surveys conducted at the juncture of the Coastal Sand Sheet and Tamaulipan Thorn Scrub ecoregions in south Texas and need to be evaluated in other arid and semi‐arid rangeland systems.

Composition and structure of a low semi-thorn shrubland in Northeastern Mexico

Background: The plant community in southern Texas and the adjacent region in Mexico is Tamaulipan thornscrub (MET). However, the recently published proposals for quantitative hierarchical classification have evidenced the presence of more communities and the need for quantitative descriptions of these associations to determine their conservation status.
 Question: What is the structure and floristic composition of a semi-thorn shrubland in Reynosa’s northwestern region?
 Studied species: Tamaulipan low semi-thorn scrubland.
 Study site and dates: Hills in Reynosa’s northwestern region (Tamaulipas), Mexico. August 2018-July 2019.
 Methods: Abundance, height and coverage of each plant species were measured on 33 plots of 10 × 10 m. Horizontal structure was analyzed by Importance Value Index, vertical structure was estimated through a modification of the Pretzsch Index and in addition alpha diversity indices were calculated.
 Results: Richness was 55 species, within 54 genera and 25 families. The importance values were centered mainly in small, spineless shrub species ( Lippia graveolens , Calliandra conferta , Turnera diffusa and Krameria ramosissima ). The vertical structure presented four defined strata with 50 % of species equally represented in all strata and the remaining 50 % restricted to a single stratum (A = 2.86, Amax = 5.39, Arel = 52.98 %). The species with the highest proportional density were distributed only in stratum IV (0-1.12 m).
 Conclusions: The community is a clearly defined low semi-thorn scrubland. The structural characteristics indicate that it can be a possible transition plant association between MET and piedmont scrub. This reinforces the proposals of the recently published classification systems.
 
 
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Structure, composition and carbon stocks of woody plant community in assisted and unassisted ecological succession in a Tamaulipan thornscrub, Mexico

BackgroundEcological restoration is a process that helps the recovery of an ecosystem that has been degraded, damaged or destroyed. The success of restoration actions depend on the understanding of the processes, mechanisms and factors that guide vegetation dynamics. The restoration of plant communities can be made by unassisted (passive restoration, where the community recover by itself) and assisted (active restoration) ecological succession. It is imperative to know the scope of both types of activities to guide future restoration actions by evaluating the properties and functioning of the intervened communities.MethodsVariance analysis of the carbon (C) stocks, basal area, canopy area, Shannon–Weaver index values, specific richness and abundance of three Tamaulipan thornscrub communities (assisted natural succession area, unassisted natural succession area and control area) was performed. Furthermore, a similarity analysis between the sampling areas using the floristic composition (abundance) was performed.ResultsIn total, 11 families, 17 genera and 20 species of vascular plants were registered. The richness of species and abundance ranked as follows per area: assisted ecological natural succession > control > unassisted ecological natural succession. The species composition between sampling areas showed a low number of common species between plant communities.ConclusionsThe values of species richness, diversity, abundance, basal area, and canopy area of the assisted natural succession vegetal community was statistical similar to the control plan community. The values of C stocks showed that assisted ecological succession could recover not only structure and composition attributes but also this key ecosystem property.

Effect of induced warming on seedling emergence of Tamaulipan thornscrub at northeastern Mexico

We carried out two experiments to test the effect of temperature increase and distance to the edge of remnant vegetation on seedling emergence, speed of seedling emergence, and seedling species diversity from Tamaulipan thornscrub. We carried out one experiment during the dry period, and a second one in the rainfall season. For both experiments, we collected 60 soil samples of 30 × 60 cm by 4 cm depth in a remnant Tamaulipan thornscrub fragment, from 5 m from the edge to the interior of remnant vegetation in a grid of six columns (15 m apart) per 10 rows (17 m apart). We divided each sample into two. One was set to grow in trays inside six acrylic open-top chambers (OTCs) to simulate global warming and the other in trays next to them, outside the OTCs. Mean temperature was 1 °C higher inside OTCs during the irrigation experiment and 2 °C higher during rainfall trial. We used generalized linear mixed models (GLMM) with Poisson link distribution to determine if there was an effect of the increase in temperature on the number of seedlings and species. Number of seedlings and species were similar inside and outside OTCs during irrigation trial, but there were more species and seedlings outside OTCs during the rainfall trial. For both experiments, speed of seedling emergence was similar inside and outside OTCs. Increased temperature affected number of seedlings and species, diversity, and abundance more than distance to the edge of the thornscrub fragment. Simulated warming under rainfall seems to decrease number of species, diversity, and abundance of seedlings; however, this difference could be due to other aspects not considered in this study. Further studies might consider seed dormancy and viability variations in the soil seed bank throughout the year.

Effects of Scarification, Phytohormones, Soil Type, and Warming on the Germination and/or Seedling Performance of Three Tamaulipan Thornscrub Forest Species.

The Tamaulipan thornforests of south Texas and northeast Mexico are an ecologically and economically important conservation hotspot. Thornforest restoration is limited by native tree and shrub seedling availability for planting. Seedling shortages arise from low seed availability and knowledge gaps regarding best practices for germinating and growing the 70+ thornforest species desired for restoration plantings. To fill key knowledge gaps, we investigated three ecologically important thornforest species with low or highly variable germination or seedling survival rates: Ebenopsis ebano, Cordia boissieri, and Zanthoxylum fagara. For each, we quantified the effects of different dosages of chemical seed treatments used to promote germination (sulfuric acid, SA; gibberellic acid, GA; indole-3-butyric acid, IBA) on germination likelihood and timing. We also quantified the effects that these chemical seed treatments, soil media mixture type, and soil warming had on seedling survival, growth, and root morphology. Ebenopsis germination peaked (>90%) with 40–60 min SA treatment. Cordia germination peaked (40%) with 100 mg/L GA treatment. Zanthoxylum germination was negligible across all treatments. Seed molding was rare but stirring during SA treatment reduced Ebenopsis molding by 4%. Ebenopsis seedling survival, height, leaf count, and root morphology were minimally affected by seed treatments, generally reduced by warming, and influenced by soil mix, which also mediated responses to warming. These results suggest improvements to existing practices that could increase Ebenopsis germination by 10–20% and potentially double Cordia germination.

Tamaulipan thornscrub after fire: an analysis of the composition of species.

Forest fires are a natural element in many terrestrial ecosystems, in Mexico one of the main causes of loss of vegetation coverage is related to them. Nevertheless, no research has been carried out in the Tamaulipan thornscrub communities regarding post-fire regenerative strategies of plant species, therefore, is important to generate knowledge about the ecological role of fire in them. The aim of this study is to characterize the arboreal and shrub vegetation of a Tamaulipan thornscrub community in the Northeast of Mexico after a fire. To determine the composition, diversity and structure of the floral community consisting of trees and shrubs, 6 square-shaped sampling sites of 1,600 m2 were established 3 years after the fire. Margalef (DMg), Shannon-Weiner (H') and Pretzsch (A) indices were calculated to determine the richness, diversity and vertical stratification of species, respectively.23 species, 21 genera and 14 families of vascular plants were registered. The most species were Fabaceae (6) and Rhamnaceae (3) and Cordia boissieri was the specie with greater ecological weight (IVI = 20.3%). The indexes of richness and true diversity (DMg = 3.16; D = 16.44) showed high values, which suggests that the post-fire area has a good regeneration and a high species diversity. With these results we can conclude that the fire is an important agent of change in successional stages of Tamaulipan thornscrub with high values of regeneration after a surface fire.

Potential Effects of Climate Change on the Geographic Distribution of the Endangered Plant Species Manihot walkerae

Walker’s Manihot, Manihot walkerae, is an endangered plant that is endemic to the Tamaulipan thornscrub ecoregion of extreme southern Texas and northeastern Mexico. M. walkerae populations are highly fragmented and are found on both protected public lands and private property. Habitat loss and competition by invasive species are the most detrimental threats for M. walkerae; however, the effect of climate change on M. walkerae’s geographic distribution remains unexplored and could result in further range restrictions. Our objectives are to evaluate the potential effects of climate change on the distribution of M. walkerae and assess the usefulness of natural protected areas in future conservation. We predict current and future geographic distribution for M. walkerae (years 2050 and 2070) using three different general circulation models (CM3, CMIP5, and HADGEM) and two climate change scenarios (RCP 4.5 and 8.5). A total of nineteen spatially rarefied occurrences for M. walkerae and ten non-highly correlated bioclimatic variables were inputted to the maximum entropy algorithm (MaxEnt) to produce twenty replicates per scenario. The area under the curve (AUC) value for the consensus model was higher than 0.90 and the partial ROC value was higher than 1.80, indicating a high predictive ability. The potential reduction in geographic distribution for M. walkerae by the effect of climate change was variable throughout the models, but collectively they predict a restriction in distribution. The most severe reductions were 9% for the year 2050 with the CM3 model at an 8.5 RCP, and 14% for the year 2070 with the CMIP5 model at the 4.5 RCP. The future geographic distribution of M. walkerae was overlapped with protected lands in the U.S. and Mexico in order to identify areas that could be suitable for future conservation efforts. In the U.S. there are several protected areas that are potentially suitable for M. walkerae, whereas in Mexico no protected areas exist within M. walkerae suitable habitat.

Caracterización estructural de una comunidad arbórea de un sistema silvopastoril en una zona de transición florística de Nuevo León

Las comunidades arbóreas con sistemas silvopastoriles desempeñan un papel importante en los ecosistemas áridos y semiáridos del país, al conservar la biodiversidad y el desarrollo de las actividades ganaderas, que son de vital importancia en el norte de México. Con el objetivo de caracterizar una comunidad arbórea de un sistema silvopastoril en una zona de transición de matorral espinoso tamaulipeco y mezquital en Nuevo León, se establecieron cinco sitios de muestreo de 2500 m2, en los cuales se realizó un inventario de todas las especies arbóreas con diámetro a la altura de 1.30 m (DAP) igual o mayor que 7.5 cm. Se evaluaron composición y estructuras vertical y horizontal a través de parámetros estructurales de la vegetación (abundancia relativa, frecuencia relativa, dominancia relativa), índice de valor de importancia, índice de valor forestal y modelos para las variables diámetro normal - área de copa. Las especies principales desde el punto de vista ecológico fueron Prosopis laevigata (Hump. & Bonlp. ex. Willd.) M. C. Johnst. y Ebenopsis ebano (Berland.) Barneby & J. W. Grimes, la comunidad presentó alta densidad de individuos, alta cobertura de copa y una estructura vertical con alta proporción de individuos con altura mayor o igual a 6 m. El modelo lineal mostró los mejores ajustes al presentar un R2 = 0.621. El manejo silvo-pastoril ha conservado y promovido los atributos estructurales de la comunidad vegetal nativa.

Ten Native Tree Species for potential use in Soil Bioengineering in northeastern Mexico

Background: Due to causes such as small-scale earthquakes or the increasing amount of heavy rainfall extreme events, many slopes are potentially unstable. Soil bioengineering is an effective tool for treatment of a variety of unstable and/ or eroding sites.
 Question and hypothesis: Maximum force to breakage of the roots is influenced by diameter.
 Tensile strength and modulus of elasticity of roots is different between species of the two different ecosystems: Tamaulipan thornscrub and Pine-oak forest.
 Studied Species: Site 1: Acacia berlandieri, Cordia boissieri, Acacia rigidula, Havardia pallens, and Acacia farnesiana ; Site 2: Quercus rysophylla, Pinus pseudostrobus, Quercus canbyi, Quercus polymorpha, and Arbutus xalapensis .
 Study area and dates: Tamaulipan thornscrub in Northeastern Mexico (Linares, Nuevo León), from May to July 2016; and Pine-Oak forest in Sierra Madre Oriental, Iturbide, Nuevo Leon, from September to October 2016.
 Methods: The species considered were selected based on their native characteristics (natural distribution, abundance in the area and widespread existence on slopes). The tests were conducted with the Universal Testing Machine Shimadzu type SLFL-100KN.
 Results: The relationships between tensile strength (Ts) and diameters of the studied species, and root diameters and modulus of elasticity (Eroot) were negative.
 The minimum and maximum values of tensile strength varied from 1.86 N / mm2 in C. boissieri to 44.65 N/mm2 in A. rigidula .
 Conclusions: Acacia berlandieri showed the highest tensile strength among all species of the two ecosystems, in the diametric group I (0.1 to 2.9 mm).

Almacenamiento de carbono en la reserva ecológica de Ternium en Pesquería, Nuevo León

La reserva ecológica Ternium es un área de conservación de flora y fauna, que incluye al Matorral Espinoso Tamaulipeco. En este estudio se cuantificó el almacenamiento de carbono en las diferentes áreas de la reserva ecológica. Se realizó un muestreo estratificado al azar con imágenes satelitales para definir las comunidades. En ellas, se muestrearon 10 sitios rectangulares de 10 × 20 m (100 sitios en total) en los que se evaluó el diámetro basal, la altura total y los diámetros de copa de cada individuo con diámetro basal > 3 cm. Para determinar el almacenamiento de carbono se estimó la biomasa mediante ecuaciones alométricas y, una vez calculada la biomasa, se utilizó el factor de 45.4 % para la estimación de carbono propuesto para especies del Matorral Espinoso Tamaulipeco. Se registraron 16 familias, 27 géneros y 28 especies. La comunidad vegetal que presentó mayor biomasa total y contenido de carbono fue la de Mezquite-Huizache con 102.44 y 46.10 Mg ha-1, respectivamente; mientras que en las comunidades vegetales derivadas de plantaciones forestales se registraron las cifras más bajas (1.74 y 3.96 Mg ha-1). En general, el contenido de carbono promedio en el área fue de 12.77 Mg ha-1. Los taxones que contribuyeron a capturar la mayor concentración de carbono por sus dimensiones fueron: Prosopis glandulosa, Acacia farnesiana y Cercidium macrum.

Wood carbon and nitrogen of 37 woody shrubs and trees in Tamaulipan thorn scrub, northeastern Mexico

Wood carbon and nitrogen of 37 woody shrubs and trees in Tamaulipan thorn scrub, northeastern Mexico

Análisis estructural de un área agroforestal en una porción del matorral xerófilo del noreste de México

Antecedentes y Objetivos: Los estudios de comunidades vegetales permiten conocer los impactos causados por las actividades agrícolas y pecuarias, especialmente en las zonas áridas. El objetivo de este trabajo fue contrastar la diversidad, composición y estructura de los estratos arbóreo y arbustivo de tres áreas (Agroforestal, Regenerada y Referencia) del matorral xerófilo.Métodos: Se establecieron tres áreas con cuatro sitios de muestreo de 1600 m2 cada una, elegidos al azar, en donde se censaron y registraron los individuos arbóreos y arbustivos. En cada área se calcularon parámetros ecológicos, así como los índices de Shannon y Margalef.Resultados clave: Considerando las tres áreas, se registró un total de 25 especies de plantas vasculares pertenecientes a 22 géneros y 15 familias. Fabaceae fue la familia mejor representada con nueve especies, siendo el género Acacia el que tuvo un mayor número (tres). Los valores de riqueza de especies, el índice de Shannon, índice de Margalef y abundancia, entre el área Referencia y Agroforestal, fueron similares, y en ambos los resultados fueron significativamente mayores que los valores del área Regenerada. El área Agroforestal presentó menor abundancia pero mayor dominancia comparada con las otras dos áreas estudiadas y fue el área que alcanzó el mayor porcentaje de similitud con el área de Referencia.Conclusiones: La actividad Agroforestal contribuye en cierta manera con el mantenimiento de la diversidad y la composición de plantas vasculares del matorral espinoso tamaulipeco estudiado; y dicha actividad no permite cambiar en gran medida la composición y estructura de este tipo de vegetación.