Introduction

Pinus chiapensis (Martínez) Andresen lacks in many areas of site index (SI) models to classify timber productivity.

Objective

To develop a dynamic SI equation, using the generalized algebraic difference approach (GADA) to describe the dominant height growth pattern and classify the productivity of natural stands of P. chiapensis in Puebla and Veracruz, Mexico.

Materials and methods

Four theoretical growth models were used to derive six equations in GADA, fitted to dominant height-age observations from stem analyses of 31 trees. Fitting was performed using the Dummy variable method, which is invariant to the base age; autocorrelation and heteroscedasticity were corrected.

Results and discussion

Quantitative evaluation, graphical analysis of residuals and growth trends of equations allowed the selection of an equation derived from the Levakovic II model with higher predictive capacity. With this equation and a base age of 50 years, polymorphic SI curves with variable asymptotes were constructed to classify productivity into low, medium and high, corresponding to SI of 25, 32 and 39 m, respectively. The maximum mean annual increase for the SI of 32 m was 1.07 m∙yr^-1 and occurred at 11.08 years. The equation exhibited better performance relative to a previously reported polymorphic equation.

Conclusions

It is recommended to use the developed equation to predict dominant height growth and SI of P. chiapensis stands in Puebla and Veracruz, Mexico.

Introduction

Tree rings play a significant role for the reconstruction of climate variables on century scales.

Objective

To reconstruct the variability of precipitation for the western part of the state of Chihuahua, based on tree rings of Pseudotsuga menziesii (Mirb.) Franco, Pinus arizonica Engelm. and Pinus strobiformis Engelm.

Materials and methods

Samples were extracted with a Pressler drill, dated and growth indexes were generated based on dendrochronological techniques. A correlation analysis was run between regional chronology and observed precipitation data. A regression model was used to reconstruct precipitation. A spectral analysis determined the recurrence of droughts and the influence of El Niño Southern Oscillation (ENSO) on precipitation variability.

Results and discussion

The relationship between the chronologies was statistically significant and a regional series of 359 years was developed. October-June precipitation had the highest impact on growth (r = 0.73, P < 0.01), so the variability of precipitation for that period was reconstructed for the last 359 years. Severe droughts were detected in the periods 1751-1768, 1807-1810 and 1945-1956 and a recurrence of droughts every 50 years was identified. The reconstructed precipitation variability is significantly modulated by ENSO at different time scales and frequencies.

Conclusion

Paleoclimatic series help us to spread the knowledge of climate in specific geographic regions and to analyze the recurrence of extreme events (droughts).

Introduction

Mangroves provide environmental goods and services that mitigate climate change.

Objective

To estimate the economic value of the carbon stock in the aboveground biomass of mangroves in Bahía del Tóbari (BT) and El Sargento in Sonora.

Materials and methods

Field research were conducted in 2014 and 2015 in 16 plots (10 x 10 m). Biomass of Laguncularia racemosa (L.) Gaertn, Rhizophora mangle L. and Avicennia germinans (L.) L. was determined with specific allometric equations. Carbon stocks and avoided CO₂e emissions were estimated with conversion factors 0.5 and 3.7, respectively; these data represented the 2015 baseline. The 2020 estimates included changes in mangrove cover. The economic value was determined using the marginal carbon abatement cost method.

Results and discussion

The 2015 baseline indicated reserves of 52.1 MgC∙ha^-1 and 191.2 tCO₂e∙ha^-1 for BT, and 71.7 MgC∙ha^-1 and 263.2 tCO₂e∙ha^-1 for El Sargento. By 2020 avoided emissions of 69 368.2 tCO₂e∙TA^-1 (TA = 362.79 ha) were estimated for BT and 116 696 tCO₂e∙TA^-1 (TA = 468.32 ha) for El Sargento. Economic values of these emissions were 131 799.5 USD (World Bank) and 180 357.2 USD (voluntary carbon market) for BT and 221 722.2 USD (World Bank) and 303 409.4 USD (voluntary carbon market) for El Sargento.

Conclusions

The highest estimates of C reserves and economic value were recorded at El Sargento. Compared to other studies in the region, both sites had higher avoided CO₂e emissions.

Introduction

Triglycerides (TG) represent 98 % of the vegetable oils composition. The evaluation of TG in pumpkin seed extracts is valuable to perceive effects caused by domestication.

Objective

To compare the triglyceride profile of wild versus domesticated pumpkins by reversed-phase HPTLC.

Materials and methods

Wild pumpkins (Cucurbita foetidissima Kunth and C. radicans Naudin) seeds were collected at mature stage at three sites of the Mexican Plateau and seeds of domesticated pumpkins (C. pepo L., C. moschata Duchesne, C. argyrosperma K. Koch) and sunflower (Helianthus annuus L.) were acquired. Ground seeds were Soxhlet extracted with hexane to obtain the lipids. From the neutral lipid extract, TG were separated on 20 x 10 HPTLC Silica Gel 60 glass plates. Unsaturated TG were used as reference. The bands, in different tracks, were analyzed with the free-to-use GelAnalyzer software.

Results and discussion

The TG profile of both wild and domesticated pumpkin seed extract shows similarity among their most abundant bands. In both samples, TG 18:2/18:2/18:2 predominates. In wild pumpkins, TG 18:3/18:3/18:3 bands stand out. Domesticated pumpkins have lower TG with higher unsaturation chain, than wild species, which gives them a greater nutritional value.

Conclusions

Wild pumpkin seeds show a characteristic profile of unsaturated TG. Chromatographic profiling and image analysis with GelAnalyzer led to the sample’s differentiation based on the bands found.

Introduction

Zadiprion Rohwer is a genus of sawflies including seven species that cause defoliations in coniferous forests.

Objective

To determine the species of Zadiprion sawflies infesting Pinus cembroides (Zucc.) in Miquihuana, Tamaulipas.

Materials and methods

Biological material was collected from sawfly larvae. Part of the material was preserved in 70 % alcohol for morphological description, another in 96 % anhydrous alcohol for molecular identification and another portion was placed in a Binder 720 KBW E5.1 to complete the biological cycle and obtain adults. The ovipositor of the female and phenology during five years were described.

Results and discussion

The sawfly larva has an orange-brown head with a small circular eyestalk, a longitudinal brown spot on the dorsum, two white lines on the sides and a dark subdorsal stripe. The female is light yellow with dark sutures on the thorax. The lancet of the ovipositor has nine rings; the first is inverted “U” shaped. Males are mainly black with yellowish legs and a yellowish-brown spot in the postocellar area; there is no yellowish-brown pronotum or tegula and the harpes are rounded and pale at the apex. The population is different from Z. rohweri (Middleton) and Z. jeffreyi (Smith), reported in GenBank; however, they are related.

Conclusion

The sawfly under study is a new species and was recorded as Zadiprion borjai sp. nov. (GenBank: ON181557).

Introduction

Climate change will have a differential impact on mountain forest growth linked to elevation.

Objective

To evaluate the interrelationships of growth ring components at the altitudinal gradient limits of Pinus hartwegii Lindl. in three mountains of east-central Mexico.

Materials and methods

We analyzed 295 tree samples from Cofre de Perote, Pico de Orizaba and Monte Tláloc corresponding to the period 1960-2017 with a total of 17 700 observations per variable (ring width and density [TRW, TRD], earlywood [EWW, EWD], latewood [LWW, LWD] and minimum and maximum density [MID, MAD]).

Results and discussion

Growth parameters were higher at the lower limit (≈3 500 m). The correlation of TRW with EWW (r ≥ 0.95) and LWW (r ≥ 0.78) was significant (P < 0.05). TRD correlated with EWD (r ≥ 0.83) and MID (r ≥ 0.72), as well as EWD with MID (r ≥ 0.92) and LWD with MAD (r ≥ 0.92). At the upper limit (≈4 000 m), correlations of TRW, EWW and LWW with TRD, EWD and MID were negative (-0.3 ≥ r ≥ -0.8). This may be explained by lower temperatures and growth periods reducing the relative importance of latewood in ring width.

Conclusion

The information provided contributes to understand the dynamics of P. hartwegii xylogenesis in response to climate and possible implications for radial growth facing climate change.

Introduction

A species\' populations differ across its distribution due to selection pressure from the climate gradient.

Objective

To describe the phytochemical variation among 14 tree provenances in an altitudinal gradient of Abies religiosa (Kunth) Schltdl. & Cham. to determine if there are associations of chemical profiles among populations, expressed under a single environment.

Materials and methods

Seeds were collected from 165 trees from an altitudinal transect from 2 850 to 3 540 m in Cerro San Andrés, Municipio Libre de Hidalgo, Michoacán, Mexico. The plant was grown in a common garden trial; at 28 months, mature needles were collected per tree and analyzed by gas-mass chromatography. Data were analyzed with diversity indices, ANOVA and multivariate analysis (principal components, correspondences and cluster).

Results and discussion

Thirty-two compounds were identified, most of them terpenes. The populations showed differences in presence/absence of terpenes and in their concentration; above 3 350 m, diversity was lower, but with higher concentration. Three altitude groups were found based on the chemical profile of the populations: low = 2 850 to 3 300 m and 3 400 m; moderate = 3 350, 3 450 and 3 500 m; and high = 3 540 m.

Conclusions

The diversity and concentration of terpenes in A. religiosa varied depending on the altitude of populations. There are three chemical profiles that should be considered in the implementation of germplasm collection programs for reforestation and restoration.

Introduction

Rhynchophorus palmarum L. is the most destructive pest in Cocos nucifera plantations in Mexico.

Objective

To estimate the cost-benefit of collecting R. palmarum by trapping in two coconut genotypes and to determine the correlation of trapping with environmental factors.

Materials and methods

R. palmarum insects were captured on the genotypes ‘Alto Pacífico ecotipo 2’ (AP) and ‘Enano-Verde de Brasil’ (EVB) for one year. Five types of traps were used (BT = bucket type, TCT = trash can type, GT = gallon type, CSAT = Colegio Superior de Agricultura Tropical, BT = bottle type). Trapping was counted weekly, and the cost-benefit of trapping was determined. Trapping was analyzed with quasi-Poisson distribution, deviancy analysis and least significant difference. Trapping correlation with climate variables was determined with the Spearman\'s coefficient.

Results and discussion

A total of 3 414 insects were captured in AP. TCT and CSAT were the most effective (P < 0.014) with 40.3 % and 32.7 % of the total adults, respectively; they also had the best cost-benefit, 4.3 MXN and 5.5 MXN per insect, respectively. In EVB, 3.56 times more insects were captured (4 799) compared to AP with a 29.6:6.4 ratio, using GT. In both orchards, the correlations of climate variables with trapping were weak (less than 50 %); relative humidity was the most highly correlated, but negative.

Conclusions

The efficiency of traps and their cost-benefit will allow growers to determine which trap to use for mechanical and ethological (aggregation pheromone) control of R. palmarum.

Introduction

The spread of agricultural use leads to changes in vegetation cover, loss of biodiversity and ecosystem services.

Objective

To analyze land use change and its effect on natural vegetation in the region of Los Ríos, Tabasco, Mexico, during the period 1947-2019.

Materials and methods

A total of 14 land use and vegetation classes were identified using aerial photographs from 1947 and supervised classification of satellite images, verifying those from 1947 to 2000 with published cartography and those from 2019 (Landsat 8) in the field. Land use and vegetation cover change was analyzed by overlaying and comparing the maps with the Land Change Modeler module integrated in the TerrSet program.

Results and discussion

In 72 years, natural vegetation was mostly replaced by crops, grassland and forest plantations, followed by human settlements. These uses, together, represented 14.2 % of the region\'s surface and increased to 61.8 %; that is, an increase of 435 %. These uses replaced areas of rainforest, secondary vegetation and hydrophytes, which went from 82.3 % to 29.7 %, representing a loss of 64 % of these coverages. Between 1947 and 1984, natural vegetation suffered the greatest loss of area (53.7 %).

Conclusions

The loss of natural vegetation in the region occurred because of the increase in agricultural land and human settlements. The increase in agricultural land was driven by government programs without considering the environmental factor.

Introduction

Forests provide environmental goods and services associated with the forest ecosystem, such as carbon sequestration, which has market potential to contribute to profitability and sustainability of forestry activities.

Objective

To estimate biomass and aboveground carbon during the development stages of a Pinus patula Schiede ex Schltdl. & Cham. forest, cultivated in the ejido Atopixco, Zacualtipán, Hidalgo, to know the potential of the species for climate change mitigation.

Materials and methods

Aerial biomass was estimated by non-destructive method, using direct measurement of height and diameter at breast height. The volume estimated for the trees sampled, at each stage of development, was multiplied by the basic wood density and the carbon coefficient of 50 % was used.

Results and discussion

The average biomass of mature trees was 294.8 kg. Estimates of aboveground carbon at the developmental stages of P. patula were as follows: brinzal (0.94 Mg C·ha^-1), monte bravo (3.73 Mg C·ha^-1), vardascal (5.05 Mg C·ha^-1), latizal (18.18 Mg C·ha^-1) and fustal (81.40 Mg C·ha^-1). The non-destructive method allowed reliable estimates of carbon content of this species.

Conclusion

Carbon storage quantification by stages of development of P. patula is useful marketing strategies of environmental services for carbon sequestration, which has imminent market potential to mitigate the impacts of climate change.