Carbon stored in forest plantations in The Mariano Dámaso Beraún District, Huánuco – Perú

The objective of the research work was to estimate the carbon stored in the forest plantations in the district of Mariano Dámaso Beraún, and for this allometric equations were used, which allowed determining the biomass and this, in turn, the above-ground carbon; Soil organic carbon (COS) was also estimated and the relationship between them was determined. The study was carried out in three 1,5 year old forest plantations, located in the following altitudinal strata: 787 masl (Quesada), 1.153 masl (Chincamayo) and 1.455 masl (Corazón de Jesús), located in the Mariano Dámaso Beraún district. , Leoncio Prado province, Huánuco department. The established species were: Schizolobium amazonicum Huber ex Ducke (spiny pine), Licaria trianda (Swartz) Kostermans (cinnamon moena), Inga edulis C. Martius (guaba), Swietenia macrophylla G. King (mahogany) and Juglans neotropica Diels (walnut); and as a result, the aerial biomass was 2,34 t/ha for the altitude of 787 msnm., 1,77 t/ha for the altitude of 1.153 msnm., and 1,63 t/ha for the altitude of 1.455 msnm.; therefore, the total airborne carbon stored was 1,17 t/ha for the altitude of 787 msnm., 0,89 t/ha for the altitude of 1.153 msnm., and 0,82 t/ha for the altitude of 1.455 msnm.; the total content of organic carbon in the soil was 67,22 t/ha for the altitude of 787 msnm., 68,77 t/ha for the altitude of 1.153 msnm., and 90,09 t/ha for the altitude of 1.455 msnm.; and according to Pearson's correlation, it indicates that there is no statistically significant relationship between the total airborne carbon content with the soil organic carbon in the district under study.


Introduction
Climate change is made up of a series of alterations that the planet suffers, which are manifested mainly by the increase in temperature, changes in rain patterns and increase in sea levels (Ciesla, 1996;Ruiz, 2007). This phenomenon occurs as a consequence of the increase in the atmospheric concentration of greenhouse gases (GHG).
For their part, Llactayo et al. (2013) report for the Peruvian Amazon a deforestation rate of 103,380 ha, whose main cause is migratory agriculture; Therefore, in the shadow of the COVID-19 crisis, the Amazon is quietly suffering one of its worst moments in the face of its particular pandemic: deforestation, which only in 2020 destroyed 2.3 million hectares in the jungle, an area larger even than the entire extension of the country of El Salvador (Gestión, 2020). In any case, it is necessary to limit in this regard, that the Mariano Dámaso Beraún district is not alien to this problem, since its upper parts have been deforested in 43.31% (33,187 ha) of its extension, and only 10, 64% of this percentage (3,532 ha) is used by agriculture in different crops (District Municipality Mariano Dámaso Beraún, 2020).
In this context, forest plantations represent one of the main alternatives to mitigate climate change, since they can remove CO2 particles from the environment through the photosynthesis process and store carbon in biomass and in the soil (Ortiz and Kanninen , 2000; Montero and Kanninen, 2006). These ecosystems in turn provide goods (wood) and diverse ecosystem services (Montagnini et al., 2011), becoming an alternative to develop reforestation projects in the form of the Clean Development Mechanism (CDM), which is why it is important Obtain information on tree biomass as a means to mitigate the effects of CO2 over-accumulation in the atmosphere.
Faced with this situation, the purpose of the work was to estimate through the method of allometric equations, biomass production and airborne carbon stored in contemporary forest plantations in the massif, located in three altitudinal strata of the Mariano Dámaso Beraún district; turn estimarsoil organic carbon (SOC) stored in contemporary massif forest plantations and determine the relationship between air carbon content and soil organic carbon stored in the plantations under study.

Materials and Methods
The research took place in three 1.5-year-old forest plantations, located in different altitudinal strata, politically located in the Mariano Dámaso Beraún district, Leoncio Prado province, Huánuco department. Each area or altitude stratum is located in the Quesada, Chincamayo and Corazón de Jesús villages. The climate is hot, humid and rainy. According to data (micro station of the Micro-basin of Las Pavas), it presents an average rainfall of 3,483.60 mm / year, maximum temperature of 29.20 ° C, minimum temperature 17.50 ° C and an average temperature of 23.35 ° C. A mechanical vernier was used to measure the diameter of the trees and / or shrubs; 5 m winch to measure the total height of trees and / or shrubs; and straight shovel, Uhland cylinders (270 cm3) and polyethylene bags of 5 kg capacity, For the purposes of to estimate the carbon stored in the living aerial biomass (BAV), all the plants of each forest system or planted area were evaluated; p For individuals with diameters greater than or equal to 10 cm, the biomass was estimated using the equation proposed by ρi = Basic density of wood (g / cm3), which will be obtained from research carried out for each species.
Gave = Diameter at the height of the chest of the tree (cm).
Hi =Total height of the tree (m).
In plants with a diameter greater than or equal to 5 cm. and less than 10 cm., it has been measured at 30 cm. above ground level, and biomass was estimated using the equation suggested by Chave et al. (2005), with the only variant that the diameter was measured at 30 cm above the ground. For bushes with a diameter greater than or equal to 2.5 cm. and less than 5 cm., an adaptation of the equation proposed by Chave et al. (2005) and Nascimiento and Laurance (2001), developed specifically to estimate the biomass of small plants; the Substitution was carried out because the latter does not consider the height or the basic density of the wood for the estimation of stored aerial biomass, which is why the results showed an oversizing (even higher than shrubs with diameters greater than 5 cm.

Mean = Sum of the data Amount of data
In order to know the approximate confidence intervals for the mean, the standard error (se) was used. The following expressions were used to calculate the confidence limits above and below 95% (where the sample mean was considered, (ee) was equal to the standard error for the sample mean and 1.96 is the quantile 0.975 of the normal distribution): -Above 95% : Limit = mean + ee * 1.96.
In order to determine the dispersion of the data, the coefficient of variation was used as proposed by Calzada (1976). Finally, in order to determine the existing relationship between aerial carbon and edaphic carbon stored in each of the planted areas, the Pearson correlation coefficient was applied, where the main factor was the determination coefficient (R2).

Biomass air and air carbon stored in contemporary forest plantations in the massif, located in three altitudinal strata
Average biomass and carbon per tree and / or shrub increase as diameter classes expand. The total aerial biomass per hectare in the plantation located at 787 masl reached the maximum value of 2.34 t / ha, followed by the plantation established at 1,153 masl that registered 1.77 t / ha, and the plot located at 1,455 masl that only obtained 1.63 t / ha. Similarly, total airborne carbon stored per hectare decreases in content as altitude increases (Figure 1).

Figure 1.
Biomass and total airborne carbon stored per hectare in three altitudinal strata. In general, an inversely proportional relationship is evidenced between the soil organic carbon content versus the sampling depth, registering a greater relationship in the 787 masl stratum that generated an equation of the form Y = -0.3829 X + 30.066, being "Y" is the organic carbon of the soil and "X" is the depth of soil sampling, with a coefficient of determination of 0.9552, which allows us to affirm that the depth of the soil has a 95.52% effect on its carbon content organic. In the case of the remaining altitudinal strata, this relationship was lower because the values of the coefficient of variation were lower ( Figure 2).  Distribution of soil organic carbon with respect to depth in three altitudinal strata.

Relationship between the content of aerial carbon and organic carbon of the soil stored in contemporary forest plantations in massif
Pearson's correlation analysis shows that there is no statistically significant relationship between the total airborne carbon content with the soil organic carbon, evaluated at a depth of 30 cm. As can be seen in Table 4, the amount of total aerial carbon and total soil organic carbon stored in the plantations of the three altitudinal strata did not generate statistical significance, which is why only the equation of the form Y = -was obtained. 47.751X + 121.09, with a coefficient of determination of 0.4918, which shows an influence of 49.18% of stored air carbon on soil organic carbon ( Figure 3).

Discussion
Biomass air and air carbon stored in contemporary forest plantations in the massif, located in three altitudinal strata The total aerial biomass in the plantation of the 787 masl altitude stratum, reached the maximum value of 2.34 t / ha, followed by the plantation established at 1,153 masl. having a value of 1.77 t / ha and the plot located at 1,455 meters above sea level. with a value of 1.63 t / ha. Consequently, there is an inversely proportional relationship between altitude and total airborne carbon stored per hectare (1.17, 0.89 and 0.82 t / ha for 787, 1,153 and 1,455 meters above sea level, respectively). In this regard, Anaya (2010) in an investigation carried out in Tingo María, Huánuco -Peru, found that the carbon stored in a plantation of white bolaina (Guazuma crinita Martius), one year old, was 1.18 t / ha; Obviously, this result is very close to those found in the present study, especially in the plantation of the altitudinal stratum 787 meters above sea level, On the other hand, Molina and Paíz (2002) found that the plantations of trees with short rotation and rapid growth can store from 8 to 78 tC / ha depending on the species, places and duration of the rotation; Although the aforementioned results are higher than those obtained in the study, the lower limit (8 tC / ha) does not represent an excessive difference, and as explained by the researcher himself, it may be due to the species and planting places; Therefore, it is feasible to infer that the combination of fast growing species (Schizolobium amazonicum Huber ex Ducke and Inga edulis C. Martius), medium growth (Juglans neotropica Diels and Licaria triandra (Swartz) Kostermans) and slow growing (Swietenia macrophylla G. King), the altitudinal gradients and even the age of the plants (1.5 years). On the other hand, Ibrahim et al. (2007) affirm that in young secondary forests of Nicaragua values of 17.6 tC / ha have been determined; also reports a similar situation for carbon in the biomass of the arboreal component in pastures, being found in native pastures with trees (100 trees ha-1) carbon content of 8.2 ± 3.0 tC / ha and in improved pastures with trees (110 trees ha-1) content of 12.5 ± 3.6 t / ha. So too, Brown et al. (1997) have estimated that the carbon (C) in the biomass of primary and secondary forests varies between 60 and 230 and between 25 and 190 t / ha, respectively. It is clearly noted that the contents of airborne carbon stored in the present study are lower than those reported by the aforementioned researchers, Regarding the relationship of altitude with the structural variables analyzed, various studies in tropical forests have reported a marked and inversely proportional relationship with variables such as basal area and aerial biomass (Moser et al., 2011;Girardin et al., 2013), especially when analyzing broad altitudinal gradients. This relationship according to Girardin et al. (2013), has been quite documented, even though altitude is not considered a direct control factor of the functional characteristics of forests, but a biophysical characteristic associated with temperature, species composition, and other topographic variables and physicochemical properties of soils, which determine structural variations at landscape scales. Segura and Kanninen (2002) also argue that the accumulation of carbon stored in forest plantations is directly related to the species, the intensity of management applied, the age of the plantation and the environmental conditions of the site. Soil organic carbon stored in contemporary forest plantations in massif, located in three altitudinal strata The total content of soil organic carbon (SOC) stored up to a depth of 30 cm, shows a directly proportional relationship with altitude (67.22, 68.77 and 90.09 t / ha for 787, 1,153 and 1,455 meters above sea level, respectively). On the subject, Brown et al. (1997) has estimated that the carbon (C) in the soil can vary between 60 and 115 t / ha. For their part, Ibrahim et al. (2007) when evaluating soil organic carbon (SOC), found a range between 95.1 and 139.5 tC / ha for forest plantations and improved pastures without trees, respectively; By comparing the results of the study, it is evident that those obtained in the three strata are within the range reported by Brown et al. (1997) and close to the lower limit found by Ibrahim et al. (2007), However, it is worth relating the results of this study with those found by Herrera (2013) in forest plantations located in Costa Rica, when evaluating trees with Dbh ≥ 10 cm at an altitude between 400 and 700 meters above sea level, where it is reported that the average carbon stored in the soil of three forest plantations was 246.16 t / ha, and by strata and species it was 257.56 t / ha on average; values much higher than those obtained in the research. The difference in these results may be due to the site, the original amount of carbon in each place before establishing the forest plantation, the apparent density of the soil, the fertility of the soil, the number of trees per area, the species installed and the management. silvicultural provided. Secondly, When carrying out an analysis of the relationship between the total content of soil organic carbon (SOC) and altitude (67.22, 68.77 and 90.09 t / ha for 787, 1,153 and 1,455 masl, respectively), Parras et al . (2015) found that SOC reserves increased with altitude; likewise, a study carried out in Venezuela by Reynolds et al. (2005) showed that there is a positive and highly significant correlation between the sampling altitude and the carbon content in soils (r2 = 0.77). In this regard, according to Reynolds et al. (2005), the differences found in the SOC reserves in the different topographic positions could be related to the differential in the decomposition speed of organic matter due to the decrease in atmospheric temperature as one ascends in the altitudinal gradient. Confirming the aforementioned, Ochoa et al. (2000) identifies a positive correlation between soil organic carbon content and altitude. Rojas (1987) corroborates this trend, stating that the content of organic matter in soils increases as the average annual temperature decreases. Charan et al. (2012) refer on the subject that lower temperatures decrease the decomposition rate of soil organic matter (SOM) and lead to a longer residence time of organic carbon (CO) in the soil, as a result of a decrease in soil edaphic respiration, which reduces carbon (C) losses. In this sense, it was found that SOC reserves were increasing due to the decrease in temperature in the altitudinal gradient. The reasons for giving credit to the statements above, is that in the altitudinal stratum 1,455 meters above sea level. (Caserío Corazón de Jesús), the average temperature determined after four own evaluations was 20 ° C. Lal et al. (1998) also affirms that the carbon content in the soil depends on the factors related to its formation, but can be modified by changes in its use and management. Climatic factors and soil factors allow explaining carbon storage over long periods, while land use and vegetation changes are considered in shorter periods. The great differences in the existence of carbon between different ecological zones are presented in relation to temperature and rainfall, varying from 4 kg / m2 (40 t / ha) in arid zones, from 8 to 10 kg / m2 (80 to 100 t / ha) in the tropics and 21 to 24 kg / m2 (210 to 240 t / ha) in the polar or boreal regions; The aforementioned data, especially for tropical areas, support the results obtained in the study.(67.22, 68.77 and 90.09 t / ha). Finally, Montagnini and Finney (2011) state that it has been proven for the Caribbean region of Costa Rica that, after the soil, the vegetation above it is the second largest carbon reservoir in agroforestry systems (SAF) and forest plantations, a fact that it was evidenced in the research, given that the SOC far exceeded the aerial carbon stored in the forest plantations. Relationship between the content of aerial carbon and organic carbon of the soil stored in contemporary forest plantations in massif In the present study, Pearson's correlation analysis shows that there is no statistically significant relationship between total airborne carbon content and soil organic carbon at a depth of 30 cm. In this regard, various studies developed along altitudinal gradients have concluded that as altitude increases, aerial biomass decreases (Girardin et al., 2013, Moser et al., 2011, possibly in response to limitations in growth. that supposes the decrease in temperature, steep slopes, changes in precipitation, wind speed, or cloudiness (characteristics of high areas). And regarding the influence of relief, according to Stevenson (1982), it is a determining factor in the variation of SOC levels both in quantity and quality, What was previously discharged confirms the inversely proportional relationship between stored air carbon and altitude, and directly proportional between SOC and altitude, evidenced in the present investigation and reaffirming that there is an inversely proportional relationship between stored air carbon and SOC in 1.5-year-old forest plantations, located in different altitudinal strata (1.17 for 67.22 t / ha, 0.89 for 68.77 t / ha and 0.82 for 90.09 t / ha, respectively); highlighting that there is no statistical significance in this relationship. However, it should be noted that elevation may not be the most important factor to explain the variability in aerial biomass (Slik et al., 2010); according to Mascaro et al. (2011), the slope of the terrain and according to Culmsee et al. (2010), including the composition of species, could determine the distribution pattern of aerial biomass in tropical forests.

Conclusions
The total aerial biomass in the plantation of the altitudinal stratum 787 masl, reached the maximum value of 2.34 t / ha, followed by the plantation established at 1,153 masl. with a value of 1.77 t / ha and the plot located at 1,455 meters above sea level. with a value of 1.63 t / ha. There is an inversely proportional relationship between altitude and total airborne carbon stored per hectare, being 1.17, 0.89 and 0.82 t / ha for 787, 1,153 and 1,455 meters above sea level, respectively. In the 787 masl altitude stratum, the diameter classes with the highest stored airborne carbon content were: 2.50 -4.99 cm. with a value of 0.18 t / ha / diameter class and ≥ 10.00 cm. with a value of 0.68 t / ha / diameter class; for its part, in the stratum 1,153 meters above sea level, the class 5.00 -9.99 cm. achieved the highest concentration of stored aerial carbon, having the value of 0.44 t / ha / diameter class. The total content of soil organic carbon (SOC) stored up to a depth of 30 cm, shows a directly proportional relationship with altitude: 67.22, 68.77 and 90.09 t / ha for 787, 1,153 and 1,455 meters above sea level, respectively. Pearson's correlation analysis shows that there is no statistically significant relationship between total airborne carbon content and soil organic carbon at a depth of 30 cm.