Introduction

Land use changes represent the factor with the greatest impact on terrestrial ecosystems. The conceptual framework of ecosystem services allows understanding how changes in ecosystems affect human well-being.

Objective

To evaluate changes in five key ecosystem functions and two key ecosystem services in the Argentina Pampas between 2001 and 2018, and to analyze their relationship with land use changes.

Materials and methods

Five ecosystem functions (soil organic carbon storage, biomass carbon storage, erosion control, soil fertility and retention of excess precipitation by vegetation cover) and two regulating ecosystem services (flood regulation and climate regulation were mapped from 2001-2018 using biophysical models. The main land uses were characterized based on remote sensing data.

Results and discussion

Ecosystem functions, except for biomass carbon storage, decreased at the regional scale between 2001 and 2018; precipitation retention by cover (40.7 %) and erosion control (35.4 %) decreased the most. Also, the ecosystem services of flood regulation and climate regulation decreased 6.78 % and 6.8 %, respectively. The spatial patterns of decrease in the levels of provision of these services were associated with the replacement of natural grasslands by cropland.

Conclusion

The use of biophysical models allowed us to analyze, spatially, the dynamics of regulating ecosystem services and to evaluate their relationship with land use changes.

Introduction

Sawmilling is the most important industrial activity in the forestry sector, being the most widely used methodology for the conversion of roundwood.

Objective

To statistically compare volumetric yield and percentage distribution of sawn products by comparing two industrial technologies in ejido sawmills in the state of Chihuahua.

Materials and methods

Three ejido industries with thin-cutting technology and two with band saws were studied, the sawing coefficient with and without bark was estimated, and volumetric yield of sawn timber according to thickness, width and length was determined. Comparison between industry types was made with Student\'s T-test.

Results and discussion

Yield without bark was different between modern and traditional industries (P = 0.007) with sawing coefficients of 60.93 and 53.09 %, respectively. Log diameter and taper had no effect on yield, suggesting that yield is mainly affected by the technological capacity of sawing equipment. The percentage distribution of nominal thickness indicates that 88.90 mm wood shows the most important differences in yield according to the type of industry; however, they are not significant (P = 0.345). Furthermore, no significant differences (P > 0.05) were found in the nominal widths 101.60 mm, 152.40 mm and 203.20 mm or in the lengths from 2.44 to 4.88 m.

Conclusion

The equipment with modern technologies allows the efficient use of raw materials because the sawing coefficient was higher in modern sawmills.

Introduction

The ant Liometopum apiculatum Mayr is an insect of economic interest in Mexico, since its larvae are extracted for human consumption.

Objective

We aimed to estimate the density of L. apiculatum nests and to identify habitat variables associated with the presence of the insect in scrubland vegetation in north-central area of Mexico.

Materials and methods

The coordinates of 201 nests and a vegetation layer were used to create a distribution map of L. apiculatum in crassicule scrub, desert microphyll scrub and rosetophyll scrub. The density of nests was estimated in 27 transects of 200 m, on which circular plots were located in which 19 habitat variables were measured. The association between these and the presence of nests was determined with a canonical correspondence analysis.

Results and discussion

Crassicule scrub had the highest density of nests with 4.8 nests∙ha^-1, while in the desert microphyll scrub and rosetophyll scrub had 2.2 and 2.3 nests∙ha^-1. The presence of nests is associated with slope direction (northwest), rock, bare soil, and soil type (eutric leptosol + lithic leptosol [medium texture]), but not with the presence of agaves. It is likely that the occurrence of nests is explained by the availability of resources by vegetation type.

Conclusions

Nest density is heterogeneous depending on the type of vegetation. The ecological information collected from L. apiculatum is relevant and useful to conduct future experiments with artificial nests that contribute to sustainable use in the north-central region of Mexico.

Introduction

Soil loss caused by water erosion impacts both positive and negative fluxes of carbon to the atmosphere.

Objective

To identify the main research trends related to the influence of water erosion on soil organic carbon (SOC) redistribution and its relationship with soil and water conservation practices.

Materials and methods

Literature published in national and international journals was consulted in Web of Science, Scopus, SciELO, Redalyc, ResearchGate and Google Scholar. Research trends were analyzed using predefined keywords and grouped according to their affinity.

Results

In the period 2012-2022, 80 % of global research focused on SOC redistribution caused by the effect of water erosion and the effect of soil management and conservation practices; however, no studies were found in this regard in Mexico. Due to water erosion, programs for the construction of soil and water conservation works have been implemented in Mexico with significant success, such as sediment control dams, but the impacts in terms of C storage have not been evaluated.

Conclusions

In Mexico there are areas of opportunity to focus research at different scales: (I) analyze the redistribution of SOC caused by water erosion, (II) estimate the storage of SOC in sediments, (III) analyze the potential of mechanical soil and water conservation practices as carbon sinks, and (IV) propose a risk index of SOC loss using remote sensing.

Introduction

The economic valuation of ecosystem services provided by forests is a necessary effort for the sustainable management of forest ecosystems.

Objective

Estimating the economic direct use value expressed by non-timber forest products (NTFPs) of the Alto Paraná Atlantic forests, Paraguay.

Materials and methods

The study was carried out in a 1-ha permanent monitoring plot and the direct market price method was used. Non-timber species were identified and classified according to their uses, they were prioritized according to commercial importance and national market reference prices were applied.

Results and discussion

A total of 36 species with potential non-timber uses (medicinal, ornamental, food and handicraft) were identified, among which the following were prioritized: Didymochlaena truncatula (Sw.) J. Sm., Miltonia sp., Oeceoclades maculata (Lindl.) Lindl., Thaumatophyllum bipinnatifidum (Schott. ex Endl.) Sakur., Calazans & Mayo, Billbergia nutans H. Wendl. ex Regel, Acianthera sp. and Chusquea ramosissima Lindm. The medicinal category was the strongest category (71 %). The economic value of the prioritized NTFPs with ornamental uses and market prices per unit was 2 270 USD∙ha^-1.

Conclusions

The economic value of NTFPs from the Alto Paraná Atlantic forests represents a reference value indicating the important role of non-timber products in the sustainable management of tropical forests.

Introduction

Severe infestations by a sawfly species of the genus Zadiprion (Hymenoptera: Diprionidae), previously considered as Zadiprion howdeni, were detected in the forests of the Sierra Juárez of Oaxaca from 2018 to 2021.

Objective

The objective was to corroborate the identity and generate information on biological and ecological aspects of the defoliator Zadiprion sp. affecting Pinus trees in the Sierra Norte of Oaxaca.

Materials and methods

The biological development of the defoliator Zadiprion sp. was studied by field sampling in forests of Santa Catarina Ixtepeji. The species was identified by observing the external and internal morphological characteristics of the adult stage, based on taxonomic keys of diprionids. The number of instars was estimated by measuring the width of the larval head using digitized images and fitting a mathematical model.

Results and discussion

The species infesting the study area is not Z. howdeni but a new species named Zadiprion llanderalae nov. sp. The larvae fed on needles of Pinus oaxacana Mirov., Pinus patula Schiede ex Schltdl. & Cham. and Pinus leiophylla Schiede ex Schltdl. & Cham., with the first being the main host. The species has one generation per year. In the field, an average density of 39.2 ± 9.69 sawfly cocoons∙m^-2 was reported; 50.1 % of these were attacked by parasitoids, including wasps of the genus Exenterus (Hymenoptera: Ichneumonidae).

Conclusions

We describe the species Z. llanderalae nov. sp. and provide data on its life cycle. This information is important for the planning of its management.

Introduction

Trees in urban and peri-urban areas produce goods and services for society; therefore, it is important to know about their ecological characteristics.

Objective

We aimed to determine trees’ ecological characteristics in the peri-urban forest at the Molino de Flores Netzahualcóyotl National Park (MFNNP) in Texcoco, Estado de México.

Materials and methods

A stratified tree sampling was developed to register tree species, diameter at breast height, height, crown diameter, percentage of live crown and crown density. Species richness and diversity were calculated using Margalef, Simpson (1-D) indexes and Santamour\'s 10-20-30 rule; in addition, the urban importance value index (UIVI) was determined.

Results and discussion

Seventeen families and 22 species were identified. Eucalyptus camaldulensis Dehnh., Schinus molle L. and Casuarina equisetifolia L. represented 55 % of the sampled trees. We estimated 7 983 ± 806 trees with a density of 163 trees∙ha^-1. Diameter at breast height is 26.56 ± 2.33 cm, height 10.52 ± 0.6 m and canopy cover equals 48.2 % of the park area (4 819.88 m²∙ha^-1). Richness (≤1.67) and diversity (≤0.61) were low; the species with the highest IVIU were E. camaldulensis, S. molle and Fraxinus uhdei (Wenz.) Lingelsh. with 38.53 %, 13.89 % and 10.62 %, respectively.

Conclusions

The tree composition of the MFNNP is similar to that of an urban forest, a situation that contrasts with other natural protected areas. Areas with very low densities were identified with potential to be reforested and could increase the diversity and canopy cover to provide greater protection to the soil.

Introduction

Sustainable management of oases needs knowledge of the conditions of composition and diversity of the species living there.

Objective

Estimating and comparing the diversity and structure of vegetation in the tree, shrub and herbaceous strata of the San Ignacio oasis, Baja California Sur, Mexico.

Materials and methods

A total of 140 circular sites (500 m²) were randomly located, where 20 m² and 1 m² sites were nested to record the vegetation in the herbaceous, shrub and tree strata. Species richness, Shannon-Wiener, Simpson, Pielou and species importance value indices were used to estimate plant diversity in the strata and to characterize their structure.

Results and discussion

A total of 53 taxa were distributed in 17 orders, 25 families and 47 genera. Richness, diversity and homogeneity were higher in the herbaceous stratum (S = 41, H´ = 3.21, J´ = 8.64, respectively) and lower in the arboreal stratum (S = 21, H´ = 2.01, J´= 0.688). Regarding the importance value index, the species with the highest ecological weight was Prosopis articulata S. Watson (33.35 %) for the herbaceous stratum, Cylindropuntia alcahes (F. A. B. Weber) F. M. Kunth (65.60 %) for shrub and Phoenix dactylifera L. (92.94 %) for the arboreal stratum.

Conclusions

Vegetation richness and diversity were higher in the herbaceous stratum. This study represents a baseline of indicators useful for the evaluation of changes generated by natural or anthropogenic events in the San Ignacio oasis.

Introduction

The maximum size-density relationship (MSDR) describes the dynamics of species-mixed stands, and it is essential in the implementation of silvicultural treatments for density control.

Objective

To analyze the influence of species composition on MSDR in mixed temperate forests of Nuevo San Juan Parangaricutiro, Michoacán, Mexico.

Materials and methods

MSDR was analyzed with a potential and an exponential model under two approaches with observations of mixed species stands. The first (E1) described the MSDR trajectory without taking into account the proportion of species and the second (E2) included the proportion of species in four groups: Pinus, Quercus, other conifers and broadleaves. Both approaches were analyzed with stochastic frontier regression (SFR) and quantile regression (QR).

Results and discussion

E1 results were favorable with the use of RC, as it showed a higher trajectory of the data to define MSDR in a linear and concave manner. In E2, the allometric coefficients of the size-density relationship for the four species groups were different and RC estimated the MSDR with species proportion adequately. In shade tolerant species (other conifers and broadleaves), the estimated slope was more negative compared to intolerant species (Pinus and Quercus).

Conclusions

For mixed forests, MSDR is adequately explained when it is dependent on species composition, because it influences the behavior of the maximum density line, useful for planning density management strategies in mixed forests.

Introduction

Gmelina arborea Roxb. is planted in reforestation programs with clones to improve productivity.

Objectives

We aimed to evaluate wood properties and determine the heritability of 14 clones of G. melina to establish a genetic ranking for selection.

Materials and methods

The trial was established with a randomized complete block design (six blocks of six individuals of each clone of 36 months of age). Basal area and volume, tree morphological properties (diameter, bark, sapwood and heartwood) and wood physical properties (specific gravity, green density and moisture content) were estimated for each individual.

Results and discussion

Growth parameters were not significantly different (P > 0.05) among the 14 clones. Clone had no significant effect on specific weight and moisture content in the genetic analysis, while tree stem height had a significant impact on all variables. The clone*height interaction was not significant for the variables studied. As for genetic control, high individual heritability values were determined only for heartwood percentage. The ranking analysis evidenced that the best clones were 1, 7, 12 and 13, positioning themselves in category 1.

Conclusions

Four clones were higher regarding growth and some wood properties, showing potential for further genetic improvement of G. arborea in reforestation programs.