The color of urban dust as an indicator of heavy metal pollution
El color del polvo urbano como indicador de contaminación por metales pesados
Available online: 2019-09-02
/ pages 3-15
Introduction: Urban dust contains heavy metals (HMs) that pose a risk to human health.
Objective: To evaluate the color of urban dust as an indicator of HM pollution.
Materials and methods: Color and HMs (Ba, Cr, Cu, Pb, Mn, Ni, V and Zn) were measured in 455 dust samples, and redness and saturation rates were calculated. Based on color, groups of samples were formed using cluster analysis. Multiple regression analysis between HMs and indices by color groups was performed, as well as a Kruskal-Wallis analysis of HMs by color groups.
Results and discussion: Urban dust samples were classified as dark grayish brown (I), dark gray (II), dark olive brown (III), very dark gray (IV), grayish brown (V) and black (VI). Multiple linear regressions between color indices and HMs showed high and significant correlation (P < 0.05) in groups I, II, III and IV. Urban dust HMs were generally found in the order Zn > Mn > Ba > Pb > Cu > Cr > Ni > V. Also, Cr, Cu, Ni, Pb and Zn showed significant differences (P < 0.05) among the color groups; the samples from very dark gray to black were the most polluted, and those of dark grayish brown had lower HM contents.
Conclusions: Urban dust color is an indicator of heavy metal pollution in Mexico City.
Thematic accuracy of hotspots and wildfires in Michoacán, Mexico
Fiabilidad temática de puntos de calor e incendios forestales en Michoacán, México
Available online: 2019-09-14
/ pages 17-35
Introduction: Wildfire monitoring programs were first implemented in Mexico at the end of the last century; however, there are no studies that report their accuracy in detecting fires and hotspots.
Objective: To evaluate the thematic accuracy of hotspots and wildfire records in a region of Michoacán de Ocampo, Mexico.
Materials and methods: Rapid Eye high spatial resolution images were classified to detect fire scars. The images were crossed with hotspot maps from the MODIS sensor, processed by the National Commission for the Knowledge and Use of Biodiversity (CONABIO), and from the MODIS, AVHRR and GOES sensors, processed by the National Meteorological Service (SMN), as well as with wildfire records from the National Forestry Commission (CONAFOR). Detection rates and confusion matrices were generated to assess accuracy.
Results and discussion: The detection rate was higher with the CONABIO MODIS sensor (>75 %) in categories greater than 50 ha. The overall accuracy of hotspots was 62 %; however, the errors of omission (underestimation) and commission (overestimation) were 85 and 34 %, respectively. The fires reported by CONAFOR lack spatial coincidence with respect to scars, so the accuracy analysis was discarded.
Conclusion: The use of hotspots, according to detection rates, is ideal for fires exceeding 50 ha. The thematic accuracy of hotspots and fire records should be evaluated at the beginning of a study.
Runoff and erosion generation by simulated rainfall in a Mediterranean forest with forest management
Generación de escorrentía y erosión mediante lluvia simulada en un bosque mediterráneo con gestión forestal
Available online: 2019-09-20
/ pages 37-51
Introduction: Forest management is necessary for forest conservation and the security of
natural assets and people; however, forest management can have negative effects on some soil properties.
Objective: To determine whether forest management in a Mediterranean forest basin,
consisting of Quercus suber L. and Pinus halepensis Mill., causes increased runoff and
eroded material at slope level.
Materials and methods: Seven land-use units were selected: a) dense forest (no
management); b) recently managed cork oak forest, c) recently managed pine forest; d) cork oak forest with two years of management, e) pine forest with two years of management, f) bare terrain with herbaceous vegetation and (g) a forest road. In each area, four rainfall simulations were carried out from a height of 2 m, at a pressure of 1.7 kg·cm -2 , equivalent to a rainfall intensity of 60 mm·h -1 . An ANOVA was performed and significant differences were verified (post-hoc Tukey test, P < 0.05).
Results and discussion: The forest road and the bare terrain, areas devoid of vegetation,
produced more runoff (4 to 12 %) than more vegetated areas (<1 %). The forest road recorded significantly higher erosion values (96 g·m -2 ) than the other land uses (<4 g·m -2 )
Conclusion: There is no difference in the generation of runoff and erosion in the managed
areas, both pine and cork oak, compared to dense or unmanaged forest.
An approximate height growth and site index model for Quercus sideroxyla Bonpl. in mixed- species stands of Durango, Mexico
Un modelo aproximado de crecimiento en altura e índice de sitio para Quercus sideroxyla Bonpl. en rodales mezclados de Durango, México
Available online: 2019-10-08
/ pages 53-69
Introduction: Predictions of dominant or co-dominant height are an important element in planning forest management with timber production objectives.
Objective: To develop dominant height growth and site index (SI) equations for Quercus sideroxyla Bonpl.
Materials and methods: The height current annual increment model was fitted, and the age of the sections was estimated from a database of 29 stem-mapped plots. A taper analysis data of 37 trees was also used to reconstruct dominant height growth trajectories. Three equations based on algebraic difference approach (ADA; one anamorphic and two polymorphic) and an equation based on generalized algebraic difference approach (GADA) were used to simultaneously model the dominant height and SI.
Results and discussion: The ADA polymorphic equations were statistically better than the anamorphic equation, according to the adjusted coefficient of determination, root mean square error, mean bias, Akaike’s information criterion and log-likelihood; however, the GADA equation was better than the ADA equations. The growth curves were biologically realistic and showed SI classes at a base age of 60 years.
Conclusions: The developed equations can be used for decision making in forest management when Q. sideroxyla shows dominance over Pinus species and the main objective is timber production.
Biomass and growth of Pinus cembroides Zucc. and Pinus orizabensis D. K. Bailey & Hawksworth in response to water deficit
Biomasa y crecimiento de Pinus cembroides Zucc. y Pinus orizabensis D. K. Bailey & Hawksworth en respuesta al déficit hídrico
Available online: 2019-10-17
/ pages 71-83
Introduction: Selection of plants not adapted to the environment and low water availability are factors that limit the success of reforestation.
Objective: To determine drought resistance in plants from three provenances of Pinus cembroides Zucc. and three of P. orizabensis D. K. Bailey and Hawksworth.
Materials and methods: An irrigation experiment (38 to 45 % moisture) and a drought experiment (30 to 36 % moisture) were established for 11 months, starting with 16-month-old plants. A split-plot experimental design consisting of two moisture environments (irrigation and drought) with replicates (four blocks) nested within them was used; in each block six populations (three per species) with 10 plants per experimental unit were evaluated.
Results and discussion: The biomass in different parts of the plants was 24 to 51 % lower in drought. Pinus cembroides had greater growth in height, stem base diameter and stem and root biomass in irrigation, and greater growth in diameter and biomass of branches and root in drought than P. orizabensis. The aerial/root biomass ratio was higher in P. orizabensis, which increased by 34 % in drought. In P. orizabensis, the provenance with the best performance in both environments was the one from the highest elevation.
Conclusion: Pinus cembroides showed greater growth and drought resistance than P. orizabensis. There are differences among provenances within each species in restrictive and non-limited moisture conditions.
Growth of naturally regenerated Abies religiosa (Kunth) Schltdl. & Cham. seedlings in a nursery and genetic variation among provenances
Crecimiento de plántulas de regeneración natural de Abies religiosa (Kunth) Schltdl. & Cham. en vivero y variación genética entre procedencias
Available online: 2019-10-18
/ pages 85-96
Introduction: The forests of Abies religiosa (Kunth) Schltdl. & Cham. in the Monarch Butterfly Biosphere Reserve (MBBR) serve as a refuge for the monarch butterfly.
Objective: To determine the viability of growing naturally regenerated A. religiosa seedlings in a nursery and the genetic variation associated with the altitudinal gradient among populations.
Materials and methods: Recently naturally germinated seedlings were collected in an altitudinal transect (2 960 to 3 450 m) that covered six populations of the MBBR. The plants grew for 18 months in a nursery at 3 000 m.
Results and discussion: The average survival of A. religiosa was 75 %. The plants showed significant differences in survival (P < 0.0001), height (P = 0.0430) and basal diameter (P < 0.0001) among provenances; the populations of the altitudinal extremes had the highest values.
Conclusion: Transplanting plants that naturally germinated in the forest into containers for nursery growth is feasible. The altitudinal pattern was atypical, since the populations of the altitudinal extremes had the best growth.
The relationship between quality of life, sense of belonging, and green spaces in urban environments in the city of Durango, Mexico
La relación entre la calidad de vida, sentido de pertenencia y áreas verdes en ambientes urbanos en la ciudad de Durango, México
Available online: 2019-10-19
/ pages 97-111
Introduction: Green spaces are important sources of ecosystem services in urban environments; however, human and economic resources and climatic factors significantly affect management.
Objective: To analyze the relationship between density of green spaces, quality of life, and sense of belonging in the city of Durango, Mexico.
Materials and methods: Green spaces were quantified and their density per inhabitant was estimated. A principal component analysis was made to reduce the number of variables that could explain the quality of life and the sense of belonging. Through factorial analysis and generalized linear models, the variables that best explain the quality of life, sense of belonging, and their influence on the density of green spaces were analyzed.
Results and discussion: The density of green spaces is 3.7 m2 per inhabitant, which is less than the 9 m2 per inhabitant recommended by several studies. The analysis of variance of generalized models indicates that the higher the density of green spaces, the higher the quality of life (P < 0.01); however, no significant evidence (P > 0.05) of a relationship between the density of green spaces and the sense of belonging, individually or combined with quality of life, was found.
Conclusion: The availability of green spaces decreases and worsens as marginalization increases.
Does the earthworm favor the survival and growth of Abies religiosa (Kunth) Schltdl. & Cham. seedlings in a nursery?
¿La lombriz de tierra favorece la supervivencia y el crecimiento de plántulas de Abies religiosa (Kunth) Schltdl. & Cham. en vivero?
Available online: 2019-11-29
/ pages 113-121
Introduction: In nurseries, irrigation inside plastic bags contributes to soil compaction, affecting plant growth.
Objective: To evaluate the effect of the earthworm Pontoscolex corethrurus Müller on the survival and growth of Abies religiosa (Kunth) Schltdl. & Cham. plants and on soil compaction in a nursery.
Materials and methods: The plants were subjected to three treatments (adult earthworm, two juvenile earthworms and no earthworms) in plastic bags (250 cc, 400 gauge) with 25 replicates. One year later, the height, cover, number of primary and secondary branches and biomass production (root, stems and branches) of the plants were recorded and soil compaction evaluated.
Results and discussion: The earthworm promoted an increase of 28 % in height and 44 % in root dry matter production (P < 0.05) without affecting survival, which was similar (86 ± 4.25 %; P > 0.05) in all three treatments. Compaction was significantly lower (48 %, P < 0.0001) in the earthworm treatments.
Conclusion: P. corethrurus has the potential to improve the quality of plants grown in plastic bags in forest nurseries.
Radial growth of pine species in stands subject to selection cutting in Santa María Lachixío, Oaxaca, Mexico
Crecimiento radial de especies de pino en rodales sujetos a cortas de selección en Santa María Lachixío, Oaxaca, México
Available online: 2019-11-01
/ pages 123-139
Introduction: The evaluation of the effect of management activities on trees is essential to gain a better understanding of the processes occurring in the stands.
Objective: To evaluate the effect of selection cutting on the growth of pine species in uneven-aged stands.
Materials and methods: Thirty sampling sites were established in two mixed pine stands subjected to selection cutting in 2003. The stumps of this harvest were used as site centers and the growth of the residual trees was evaluated in a 10-m radius; tree-size variables and competition indices were calculated.
Results and discussion: In the first five years after the harvest, 47 % of residual trees showed significant growth (P ≤ 0.05). Stump diameter, diameter at breast height and competition were the most important variables to explain growth. The competition area of the harvested individuals (stumps) showed influence up to a 15-m radius. The increase in basal area (IBA) was 71 % with respect to pre-harvest growth. This increase was related to the basal area sum of the residual trees and 1.3 m2 per site (41.3 m2·ha-1) was established as the threshold from which a release is nullified by residual competition.
Conclusion: Selection cutting influences residual tree growth in a differentiated way; the response may be positive, negative or nil depending on size and local competition.
Does fertilization hardening improve the morphometric and physiological characteristics of Pinus rudis Endl. seedlings?
¿El endurecimiento mediante fertilización mejora las características morfométricas y fisiológicas de plántulas de Pinus rudis Endl.?
Available online: 2019-11-04
/ pages 141-153
Introduction: Forest management is necessary for forest conservation and the security of natural assets and people; however, forest management can have negative effects on some soil properties.
Objective: To determine whether forest management in a Mediterranean forest basin, consisting of Quercus suber L. and Pinus halepensis Mill., causes increased runoff and eroded material at slope level.
Materials and methods: Seven land-use units were selected: a) dense forest (no management); b) recently managed cork oak forest, c) recently managed pine forest; d) cork oak forest with two years of management, e) pine forest with two years of management, f) bare terrain with herbaceous vegetation and (g) a forest road. In each area, four rainfall simulations were carried out from a height of 2 m, at a pressure of 1.7 kg·cm-2, equivalent to a rainfall intensity of 60 mm·h-1. An ANOVA was performed and significant differences were verified (post-hoc Tukey test, P < 0.05).
Results and discussion:
The forest road and the bare terrain, areas devoid of vegetation, produced more runoff (4 to 12 %) than more vegetated areas (
Conclusion: There is no difference in the generation of runoff and erosion in the managed areas, both pine and cork oak, compared to dense or unmanaged forest.