Currently, the global forest area is equivalent to 4060 million hectares, 45% of which is in the tropical forest zone (FAO & UNEP, 2020). Tropical forest has registered significant losses, 420 million hectares since 1990, due to changes in land cover and conversion to other land uses. This is due to natural factors such as drought, fires, storms, and diseases, and anthropogenic causes such as clearing land for agriculture, overharvesting of timber, expansion of settlements, and infrastructural developments (Keenan et al., 2015). According to Armenteras & Rodríguez (2014), the main precursors of deforestation in Latin America are associated with the expansion of the agricultural frontier including for livestock at 42.5% and population growth at 18.85%. These factors affect the provision of ecosystem services derived from tropical forests, functional diversity, and net carbon emissions due to deforestation and degradation (Houghton, 2012).

In Colombia, tropical dry forests (BsT) are considered a strategic ecosystem for the conservation of biodiversity and carbon storage. These forests represent 735,514 ha, 39.2% of which are in the Caribbean region, with average aboveground biomass (AGB) of 96.2 Mg C ha^-1 (Phillips et al., 2011). Ulloa (2016) reported that more than 98% of the pristine dry to sub-humid forest cover in Colombia has disappeared because of the degradation and conversion of forest formations to extensive cattle ranching.

Cesar Department, in the Colombian Caribbean region, is characterized by a livestock production of 1,529,131 head of cattle in a predominantly extensive grazing area of 1,062,415 ha (FAO & ADR, 2019). Livestock production is thus the most important agricultural activity and the precursor of deforestation, degradation, and increased greenhouse gas emission (GHG) processes. According to the GHG inventory of the Cesar Department, enteric fermentation and manure management from livestock production are responsible for 1229.66 kt CO2-eq and 83.87 kt CO2-eq, respectively (MADS, 2015), contributing to CH4 and NO2 emissions and global climate change (Gerber et al., 2013).

The Cesar River Valley ecoregion has highly productive soils, where processes such as livestock, agriculture, agrobusiness and open-pit coal mining converge. For several decades these activities have generated negative externalities on natural resources. Elimination of tree cover, loss of topsoil, erosion processes, and compaction are examples of these processes. This deterioration is exacerbated by climate seasonality in the region; four months with low or non-existent rain days at the beginning of the year (CORPOCESAR, 2019). Although this situation presents serious limitations for the development of existing production systems, there is scope to implement consider sustainable production strategies as soon as possible to recover tree cover in agricultural and livestock. That is why an assessment strategy and recognition of the use of tree species can contribute to the restoration and sustainability of the territory.

Although livestock production systems generate deforestation processes and emit GHG, they also have the potential to conserve diversity and mitigate GHG through the implementation of silvopastoral systems (SPS) (Jose & Dollinger, 2019). SPS store carbon in aboveground biomass and soil organic carbon (Ibrahim et al., 2007). The SPS integrates trees and shrubs associated with pastures and animals, into the same area, to improve the sustainability of the livestock system (Montagnini et al., 2013). In Cesar Department, scattered trees in pastures stand out as the most important SPS.

Studies of SPS in the tropics have shown an important aboveground carbon (AGC) storage regarding natural forests. Natural pastures with scattered trees and forage banks store between 70 and 120 Mg C ha-1 (Ibrahim et al., 2007), while pastures with a high density of trees in the dry tropics of Nicaragua conserve 6.3 Mg C ha-1 (Cárdenas et al., 2019) compared with natural regeneration processes in cattle farms in the Department of Caquetá, Colombia, reach values of 32.32 Mg C ha-1 (Rojas-Vargas et al., 2019).

The IPCC (2007) estimates AGC of 141 Mg C ha^-1 in the tropical forests while Ibrahim et al. (2007) reported values of 90.78 Mg C ha^-1 and 115 Mg C ha^-1, respectively, in secondary dry forests present in cattle farms in Costa Rica and Nicaragua. In Colombia AGC storage in tropical dry forest and humid forest estimated from 46.17 Mg C ha^-1 of 124.27 Mg C ha^-1 respectively (AGB values multiplied by emission factor 0.48) (Phillips et al., 2011).

In addition to contributing to AGC storage, SPS where trees are dispersed in pastures, improve the productivity of the livestock production system through the conservation of biodiversity and landscape connectivity (Chacón & Harvey, 2013), the conservation of soils and water (Ríos et al., 2008), and the provision of timber products (TP) and non-timber forest products (NTP) for commercial or subsistence purposes. Improving the profitability of production systems whilst contributing to animal welfare (Harvey et al., 2011) has been seen through the production of forage and fruits of high nutritional quality for cattle feeding (Casasola et al., 2001), whilst the provision of wood, fence posts, and firewood reduces the impact on forests (Harvey et al., 2011) together.

The objective of this study was to determine the AGC storage present in the dispersed trees in pastures in the arid Caribbean, Colombia.

Trees dispersed in pastures of a tropical arid forest can contribute to the conservation of this ecosystem. This study assessed 28 species with a density of 17.42 + 13.93 trees ha-1. Of the species listed, 65% are important for subsistence and are associated with potential NTP uses such as live fences and medicines, shade and food resources such as fodder and fruit for cattle. Similar results regarding species richness, abundance, and use were reported by Cajas-Girón & Sinclair (2001) in four micro-regions of the Colombian Caribbean region (Litoral, Golfo de Morrosquillo, Sabanas, and Valle del Sinú). These authors found that between 70 and 90% of the trees in cattle ranches were used primarily for timber and forage. Among the timber species reported are T. rosea, S. apetala and Albizia caribaea. In the same way that this study, 83% of producers reported high dependence on forage trees such as A. saman and Cassia grandis, G. ulmifolia and C. cujete for animal feed during the grass shortage period.

In a characterization of trees in pastures of a tropical dry forest zone in the Department of Tolima, among a set of 21 species identified in pastures, Serrano et al. (2014) reported that G. ulmifolia was the species with the greatest abundance and BA (25.3% and 26%, respectively); it is used as timber for fence posts and as feed and shade for livestock. Meanwhile, in the characterization of trees dispersed in pastures in four livestock landscapes of Central America (Matiguás and Rivas in Nicaragua, and Cañas and Río Frío in Costa Rica), Harvey et al. (2011) found a mean richness between 22.9% to 45.9%, density between 7.9-33.4 trees ha^-1 and average DBH between 18.56 and 44.32 cm.

The most abundant species in our study were G. ulmifolia (46%), A. saman (16.53%), M. tinctoria (7.2%) and C. alba (5.33%). The abundance of G. ulmifolia in pastures is associated mainly with the supply of forage and fruit as an option for cattle in times of forage shortages (Manríquez-Mendoza et al., 2011). In addition, its characteristic as a pioneer species contributes to its permanence in pastures mainly by anthropic selection (Villa-Herrera et al., 2009). Tree diameter varied between 10 and 90 cm, similar to values reported by Zapata-Arango (2010) for trees in pastures in Muy Muy and Matiguás, Nicaragua, with an average of 35.1 cm; by Esquivel-Mimenza et al. (2011) in Guanacaste, Costa Rica with an average of 58.9 cm; and by Chamorro et al. (2018) in tropical dry forest conditions in Nicaragua with averages of 30.3 cm. These different studies indicate that G. ulmifolia has similar ecological characteristics in those places and its dominant density may be associated with its excellent natural regeneration capacity, due to its abundant fruit production (~17.5 kg tree^-1 with 40 to 80 seeds fruit^-1; Leyva, 2003) and its easy propagation through consumption of the fruit by birds and mammals, mainly bats and cattle.

The permit requirement was felt positively by many “in order to know who’s entering the forest” (E19). Having a picking fee is largely supported, but 27% respondents specified that “if its price is symbolic, as it’s now”. The positive side of a payment was justified as a dissuasive mechanism, as awareness-raising tool about the mushroom value, and for covering the permit costs. Moreover, a few note that with the current prices the aim was fungal conservation rather than fund-raising. Yet, most interviewed pickers were neither aware of the actual amount of money raised nor the use of the proceeds.

The second species with the highest abundance value was ^{A. saman} with 16.5% of the trees reported. These results differ from those reported by Harvey et al. (2011) with an abundance of 5% of scattered trees in pastures in Matiguás, Nicaragua, and by Esquivel et al. (2011) with an average DBH of 57.3 cm and a density of 8.1 trees ha^-1 in Guanacaste, Costa Rica. The high presence of A saman could be related to its wide distribution from Mexico to Bolivia, giving it a frequent occurrence in the tropical dry forest (Cascante et al., 2002). In addition, its rapid growth, high capacity to colonize open fields, and provision of fruits for animal consumption and shade, make it an interesting species for livestock systems (Aparajita & Rout, 2010). In addition, A. saman is also used for cultural purposes (Durr, 2001) and as a source of timber (Cascante et al., 2002).

Although we found that species with timber as their main use were less abundant than non-timber species, their density values were like those reported by Esquivel et al. (2011) for T. rosea and T. ochracea (0.56 and 0.17 trees ha^-1 respectively). Timber species continue to have an important value in cattle ranches. Villanueva et al. (2006) highlighted the preference of cattle producers in Esparza, Costa Rica, to conserve species with timber and firewood uses on their pastures out of 61.8% and 55.9% of the reported species. Esquivel et al. (2011) reported 50% of the species categorized as timber, 27% as fodder, and 27% as fruit in Guanacaste, Costa Rica (tropical dry forest).

The increase in grazing areas has led to loss of much of the carbon previously stored in the aboveground biomass (Hoosbeek et al., 2018). However, silvopastoral uses increase the carbon storage potential of pasturelands worldwide (Jose & Bardhan, 2012) and mitigates GHG (Hoosbeek et al., 2018). The value of AGC dispersed trees in pastures of 7.15 + 4.8 Mg C ha^-1 was similar to data reported by other authors in tropical dry forest conditions. Cárdenas et al. (2019) reported values of 6.3 Mg C ha^-1 in pasturelands with a high density of trees in Matiguás, Nicaragua; Chacón & Harvey (2013) reported AGB values (multiplied by 0.48) between 2.54 and 6.48 Mg C ha^-1 in four Central American agro-landscapes; Rojas et al. (2009) reported values between 4.4 Mg C ha^-1and 5.8 Mg C ha^-1 in Guanacaste, Costa Rica in pasturelands associated with Diphysa robinoides and Pithecellobium saman, respectively; and Aryal et al. (2018) reported AGB values between 10.75 and 12.72 Mg C ha^-1 in pasturelands of Chiapas, Mexico.

Differences in tree species composition, tree density per hectare, soil type, and management practices may explain variations in the carbon stocks of these systems (Cárdenas et al., 2019). Studies on silvopastoral systems in Colombia have reported higher carbon storage values in trees than this study. For example, Montagnini et al. (2013) reported AGB values between 13.65 and 28.07 Mg C ha^-1 in trees in pasturelands in the watershed of the La Vieja River in Colombia. Giraldo et al. (2006) reported AGB values between 12.22 and 19.51 Mg C ha-1 and a density of 100 trees ha^-1 in a 9-year-old silvopastoral system of Acacia mangium. Phillips et al. (2011) estimated a value of 48.1 Mg C ha^-1 for the tropical dry forest of the Caribbean region.

The potential of trees in pastures for biodiversity conservation, landscape structural connectivity, and the provision of ecosystem services has been evidenced (Montagnini et al., 2013; Jose & Dollinger, 2019) in the face of deforestation and degradation of tropical forests converted to extensive cattle production (Graesser et al., 2015). For example, large areas in Cesar are in the process of desertification with a 69% level of affectation (MAVDT, 2005) and the deforested area was estimated to be 15,655 ha in 2007 (IDEAM, 2010). These scenarios have a negative impact on the conservation of natural resources, provision of ecosystem services, and sustainability of livestock systems. Conversely, the conservation of these species can contribute to the improvement of the landscape, which is considered an ecosystem service (Cordero et al., 2008), favoring small farmers and improving their living conditions in rural areas (FAO, 2018).

The PES (Payment for Environmental Services) is an important conservation strategy at the national level (Díaz et al., 2019) and is focused on areas and ecosystems identified in the Colombian Registry of Ecosystems and Environmental Areas (REAA) and the national registry of protected areas (RUNAP), and although it is empowered to implement the incentive in Colombia, the implementation is still insufficient (DNP, 2018).

Silvopastoral systems of dispersed trees in pasture store an important amount of carbon in the above-ground biomass, as has been reported in other similar agro-ecological conditions. Trees in pastures are mainly used for non-timber uses, such as providing shade, fodder, and fruit for cattle. The species G. ulmifolia and A. saman represent the species with the highest carbon storage due to their wide distribution, abundance, and large BA. Finally, pasture production in wooded systems is important in GHG mitigation and climate change adaptation strategies by providing timber and non-timber goods and services to animals and producers.