Characteristics of the resources of the conversion areas

Based on the results of the participatory mapping of field trips and farm geo-positioning (^{Valencia-Trejo, 2020}), the map of areas of productive reconversion and detonating change projects was generated (Figure 2).

Figure 2 Map of conversion areas and detonation projects of change. 

Water quality for the production of tilapia (Oreochromis niloticus)

The growth and reproduction of fish depends on the quality of the water, for this, it is necessary to maintain the physical-chemical conditions within the limits of tolerance for the species (^{Bautista and Ruiz, 2011}). Quality is determined by temperature, oxygen, pH and transparency (^{Saavedra, 2003}). The recommended physicochemical parameters are shown in Table 2.

The analysis of water in the farm showed an optimum pH, without salt problem, the electrical conductivity is low, the total soluble solids (SST) for site 1 and 3 are of excellent water quality, exception class, site 2 it presents good quality, surface waters with low suspended solids content, generally natural conditions, favors the conservation of aquatic communities and unrestricted agricultural irrigation. Biochemical oxygen demand (BOD₅) is an indispensable parameter to determine the state or quality of water in rivers, lakes, lagoons or effluents. This indicates uncontaminated water of excellent quality at sites 1 and 2. In the case of site 3 the water quality is good, surface waters with low biodegradable organic matter content. Turbidity is in the optimal range at all sites, less than 25 UNT.

According to the WHO hardness classification, the three sites are in the range of 0-60 mg L^-1 calcium carbonate, classified as soft water; low calcium and magnesium content (^{OMS, 2006}) with optimal range of hardness for fish culture (20 to 350 mg L^-1 CaCO₃, (^{Meyer, 2004}) at site 2. For site 1, the Liming of the pond (^{Arboleda, 2006}). No heavy metal contamination, zinc, manganese and copper were found in traces at all sites; however, the iron at site 1 has values greater than recommended (Table 3). To solve this limitation, it will be necessary to filter the water through zeolite (^{Petkova, 2013}).

Carbon warehouses

Table 4 shows the carbon present in mulch, woody, leaf litter and herbaceous areas of the land destined for the enrichment of acahuales and reproduction of native species, as productive reconversion projects. The site (S3) Acahual la Hortencia-Calistemo Farm presented 0.88 Mg ha^-1 C in leaf litter and 9.25 Mg ha^-1 C in mulch. The site (S2-1) Acahual 1 Xoxocotla Farm with 1.82 Mg ha C in leaf litter and 1.65 Mg ha^-1 in mulch.

The study of carbon warehouses conducted by ^{Ruiz (2016)} in traditional ornamental cultivation systems and a BMM relic in Xaltepuxtla, in the BMM system estimated leaf litter carbon content of 0.63 Mg ha^-1 and 1.09 Mg ha^-1 in mulch. These results indicate that it took 20 years of rest from the land to allow the resilience of carbon sites. It should be noted, S3 of the Hortencia-Calistemo Farm with a high accumulation of mulch (9.25 Mg ha^-1), is because the dominant tree species are pines and oaks which provide a large amount of leaf leaf litter (ocochal) for its large carbon sequestration capacity. This high mulch value is congruent with that reported by Rodríguez-Laguna (2009) quantified at 9.88 Mg ha^-1 in pine-oak forests. Mulch is one of the main stores of carbon and mineral elements in the soil of some ecosystems (^{Vogt et al., 1986}) is a key indicator of the flow of energy and circulation of nutrients within the ecosystem.

Carbon reservoirs in trees at site S2-1= Acahual Xoxocotla-Enrique Farm have 6.64 Mg ha^-1 of carbon (Table 5) while at Site 3 (S3= Acahual Hortencia-Calistemo Farm) the carbon was of 143.95 Mg ha-1 of carbon (Table 6). The difference is explained by the characteristics of the acahual, while in the S2-1 site the species are young with a D (normal diameter with bark) less than 20 cm, even D smaller than 10 cm predominates, unlike the site S3 where there are species such as the ocote (Pinus sp.) with D of 30 cm. Acahuales have an important carbon capture and reservoir potential, in relation to primary vegetation in less time; therefore, if they continue to maintain advanced stages of succession, they can be a stable vegetation alternative that generates environmental carbon capture and biodiversity services (^{García-Domínguez et al., 2018}).

Organic carbon in soils (COS)

In (Table 7) the COS of the Xoxocotla Farm is presented at sites S1-1 (cedrela systems in productive reconversion 1) and S1-2 (cedrela systems in productive reconversion 2); as well as in the acahuales (S2-1 and S2-2). The S1-1 site presented the highest value of COS at the depth of 0-26 cm (230.33 Mg ha^-1) at this site a lot of COS has been generated due to frequent pruning for the cultivation of cedrela, these results are consistent with the ^{Ruiz (2016)} carbon study in the Xaltepuxtla bioproductive systems for the mixed ornamental system that includes cedrela (243.24 Mg ha^-1) in the first 30 cm deep.

The COS in S2-1 at the depth of 0-26 cm was 198.08 Mg ha^-1 and the S2-2 acahual was the lowest value (144.21 Mg ha^-1). Although these lands have remained at rest for twenty years, the variations in the COS with the depth in the first 26 cm are low (less than 3%), remaining in ranges 8.37 to 12.06% of soil organic matter (Figure 3a, 3b and Figure 3c and 3d). These variations can be associated with topoform and soil management within the bioproductive system. According to ^{Ruiz (2016)}, topoforms with a slope equal to or greater than 15% and the use of hoes are determinants in soil deterioration and consequently in carbon loss.

Figure 3 Distribution of the percentage of organic matter of the Farm (Xoxocotla-Eleuteria); a) S1-1; and b) S1-2. 

Figure 3 Distribution of the percentage of organic matter in the Farm (Xoxocotla-Enrique); c) S2-1; and d) S2-2. 

The Andosols, are the soils with the greatest capacity to store carbon due to the content of allophane that forms complexes with the organic matter protecting it from oxidation (^{Galicia et al., 2016}), therefore, the values reported in Figure 3 are expected for this type of soil.

Management actions

The proposal of management actions and detonating change projects, although they derive from the interest of the producers and the potential of the farm for a given productive system, it is relevant to have financing for the achievement of technological intervention. The productive reconversions must be aligned with the attention needs indicated by the agricultural and livestock sector of the state, in this case the government of Puebla and federal agencies such as CONANP. Next, the management proposals by farm are discussed.

Xoxocotla and the Farms Hortencia-Calistemo

The market shortage and low profitability of ornamental production systems have forced producers to leave farmland at rest, becoming acahuales. Within its community support programs, CONANP subsidizes acahual enrichment projects based on restoration with timber species native to the BMM, which must have both the purpose of ecosystem restoration and multiple uses of interest to producers. For this area were included: Alnus acuminata, Platanus mexicana, Heliocarpus appendiculatus, Fraxinus uhdei and Casimiroa edulis in such a way that it is attractive as a management objective in the short, medium and long term (Arévalo, 2018). Other species that may be included are Pinus pseudostrobus, Quercus sp. and Liquidambar styraciflua L.

Among the enrichment of acahuales, technologies such as live fences, live barriers and the management of non-timber species are included, of economic interest such as the production of the native fungus Entoloma avortibum known as totolcozcatl (Mateo, 2018), reproduction of orchids, bromeliads and tree fern (Cyathea salvinii), species of great economic and ecological value. In the medium term, this restoration can aspire to the payment for environmental services sponsored by CONAFOR.

Production of native species

Through management units for wildlife conservation (UMAS) of tree fern (Cyathea salvinii), bromeliads and orchids. The producers of the Xoxocotla and Ocotitla farms considered these projects.

Extension of the meliponas module

Stingless bees (Scaptotrigona mexicana) in the Sierra Norte de Puebla have been exploited domestically to obtain their honey and wax (^{Ayala, 1999}). The benefits that these bees provide as a stabilizing element of the ecological environment through the pollination of plant communities are invaluable.

Improvement and expansion of mushroom production module (Pleurotus ostreatus)

The group of producers mainly composed of medieros has already started with this project, however, the adaptation and expansion of the production module, inoculum production and the search for appropriate economic substrates require investment.

Tilapia production

While the availability and quality of water resource allows the fish activity, funding is indispensable. In 2019, these proposals were not supported by CONANP or by the state government, therefore, alternative projects must be kept in mind.

Delimitation of the area of alternative production

the following species with economic potential are recommended for the area: Bamboo (Phyllostachys aurea), grapefruit (Citrus paradisi), Granada (Passiflora ligularis) and creole avocado (Persea sp.). The conversion project proposals generated in early 2019 were managed by the UACh before the CONANP; however, there were no resources to finance these projects. Given this situation it is recommended to be attentive to the calls of SADER, SEMARNAT, CONANP, INPI to access resources. Financing management will be necessary through a civil donor association authorized by the Ford Foundation, Banamex Social Development, Root Capital and Peace Corps.