We evaluate the extend to which active fires alert in the Huascaran Biosphere Reserve were related to environmental and human population features between 2001 and 2020. The number of fire alerts constantly increased during last years, especially in the buffer zone were most people uses fire in agriculture; and reached its maximum in 2020 during the first wave of the global pandemic. A combination of both, xeric conditions, and human pressures, seem to exacerbate fire alerts occurrence along key Andean ecosystems like Puna grasslands and shrublands that are not adapted to this type of pressures. Moreover, land transformation and a limited capacity of control over key extensive areas within the National Park seem to play an important role in where and when fires occur. Hence, the effectivity of different conservation initiatives will depend on understanding how climate shapes long term and seasonal xeric condition - including the distribution of biomass that serve as fuel for fire - and how is this related to different human activities principally associated to agricultural practices.
Climate and human determinants of fires in Cordillera Blanca
While climate can provide suitable condition to wildfire to prosper, human activities usually trigger them, especially in areas where fires are not part of the natural systems (Poveda et al. 2020). If AFD in our study site were natural, we should notice their presence during months with greater prevalence of lightnings. However, lightnings occur during the rainy season (Feb - March), when much of the vegetation is wet and still growing. Contrary, our results show that AFD were especially common at the end of the dry season, after vegetation has gone through several months of drought and a larger amount of biomass were generated. Across years, our results shown an increase of AFD during dry periods (e.g. 2016 and 2020) but the reverse in wetter years (e.g. 2017 and 2018); reinforcing the hypothesis that xeric climatic characteristics (e.g. low precipitation) strongly influence fire events in the High Andes of Peru. With exception of 2003, our results agree with a previous study (All et al. 2017) in terms that 2005, 2010, 2012 were years of high fire activity. However, 2016 and 2020 were way more severe in terms of both fires and dryness. Moreover, similar results were observed in other regions of Peru and Bolivia by Roman-Cuesta et al. 2011, 2014; where years of higher fire activity were characterized by very dry periods and low temperatures but the difference that they observed an increase of precipitation the year before fire-peak (Roman-Cuesta et al. 2011, 2014). Overall, our results are supported by findings that claim that climate, including extreme water deficits and El Niño events, are the main driver of fires in different Andes regions (da Silva et al. 2018; da Silva Junior et al. 2019; Edwards et al. 2020; Poveda et al. 2020).
While climate drives the temporal pattern of fires, the spatial distribution of fires seems to be driven by people. In our study site, AFD was highly related to the number of people living on each zone of the HBR (Table 2; Figure S1). We believe that the use of fire in agriculture and in minor proportion, accidental events caused by tourist, are the main underlying factors behind this relationship.
At the end of the dry season, people located in rural areas start to feel the effects of water scarcity and therefore, the traditionally use of fire for land preparation for a new agricultural year start (Moran et al. 2006; Manta et al. 2018). This practice is widely used in the Andes and other agricultural regions and usually involves the burn of stubble - the set of remains of stems and leaves that remain on the ground after cutting a crop called “rastrojos” in Spanish-. In many opportunities, however, burning rastrojos can get out of control if it is not well managed, causing severe damages to native forest and other ecosystems. Plotting our results on a map, clearly shows that most AFD within the HNP occur close to the BZ and around the entrance of densely populated glacial valleys (Figs. 1 and 4). According to the HNP office, most wildfires recorded within the HNP started with this type of practice in the BZ, where agricultural activities are a fundamental part of the livelihoods and culture of local people. But what is in the buffer zone that can make “rastrojos” so difficult to control? The answer could be Eucaliptus and Pines forest.
It is known that landcover type can define fire intensity and flammability of an area (Paton et al. 2014). As in many parts of the Andes, Eucalyptus globulus and Pinus radiata represent key exotic species for rural livelihood whereas also reduces human pressure on native forest for logging (Luzar 2007). For several decades, both were extensively planted in the surroundings of the Cordillera Blanca, becoming part of the landscapes of the buffer and transition zones (Byers 2000). However, both have important characteristics that make them good candidates to prosper in fired conditions (Mutch 1970).
Eucalyptus forests are considered “fire-dependent” trees, due to a high natural flammability that allow them to live in balance with fires (Hodgson 1968). One characteristic that increase its flammability is the presence of oils in the leaves, which have low igniting point and required less oxygen that other plants to burn (Webb 1968). Another property is the low rate of decomposition of the litter, caused by the volatility of the oils in the leaves, which produces an accumulation of litter on the ground and leaves it exposed to the periodicity of fires (Agee et al. 1973; Mutch 1970). For Pines on the other hand, Franzese and Raffaele (2017), indicate that in addition to have specific survival adaptations to fire, such as thick bark and self-pruning capacity (Higgins and Richardson 1998), there are two very important factors that would explain the synergistic relationship between pines and fire: (1) serotiny, which is the prolonged storage of seeds in the canopy and is closely related to the responses of trees to recurrent fires (Keeley, 2012; Lamont et al. 1991), and (2) the ability of seedling to invade and prosper in burned and unburned habitats. Therefore, fire seem to be a good facilitator of Pinus radiata success in habitats affected by fires, as recruitment would be carried out quicker in burned areas.
Under technical supervision, different practices have been carried out to manage these types of forest, including continuous thinning and prescribed fire in humid conditions to control or eliminate the amount of fuel (litter) accumulated in the understory (Agee et al. 1973). Additionally, the use of controlled fire is also vital, so destructive fires do not occur (Mutch 1970). However, most local people that practice agriculture in HBR do not necessarily follow these practices but conduct the burn of restrojos quite often. We believe that the monitoring and manage of fires in the buffer and transition zones are fundamental to protect the native biodiversity of HNP. However, this may require set of well planed activities that include environmental education, logistic and personal preparation, and facilities for the ecological restoration of affected areas.
How are wildfires managed in the HBR?
Wildfires in the HBR should be managed in a hierarchical way by different institutions and key actors responsible for specific tasks, including prevention, the response, and restauration (Vallejo and Alloza 2014). However, in practice, the burden falls mainly on the HNP, the park rangers and local people who somehow respond to these events in a rather voluntary way full of conviction. The National Service of Protected Natural Areas (SERNANP) has an organic strategy for the control of wildfires framed in three components: (1) prospective that seeks to understand the causes of these fires, (2) corrective that seeks to prevent them and (3) reactive that it is implemented in response to a wildfire event (SERNANP 2018). On the other hand, the management of fire risk control is framed in the prevention, reduction, preparation, response, estimation, rehabilitation, and restoration of the affected spaces and are implemented by both SERNANP and the National Forest and Wildlife Service. (SERFOR). Currently, the PNH administration is the main responsible for strengthening the response capacities to wildfires that occur in the CZ of the RBH. These include ongoing training for park rangers and the inclusion of local people through the formation of Participatory Vigilance Committees (Comites de Vigilancia Participativa). In the buffer and transition zone, these activities most be part of the goals of various institutions that include SERFOR, Defensa Civil, and municipal and regional governments (see. Gobierno Regional de Ancash 2020, Plan de prevención y reducción del riesgo de desastres ante incendios forestales de la región Ancash 2020–2023). However, these actions do not seem to be sufficient to counteract the misuse of fire that often unleashes wildfires that are harmful to nature and man. According to Manta (2017), there is still a lack of training for key actors, as well as little equipment, and a high turnover of personnel that together prevent an adequate prevention, response, and management of wildfires in the area. We believe that it is necessary to empower good practices in the use of fire, mainly associated with livestock and agricultural practices, as well as to be able to differentiate between destructive and useful fire through controlled and prescribed burns.
The legislation behind the use of wildfire appears to be an aggravating factor for its management in the HBR. Within the HNP, fires are prohibited for several reasons including that they are not part of the high Andean natural systems and can be highly destructive of its biodiversity. However, the legal framework that applies outside the HNP is unclear given basic laws that on one hand allow the use of fire and on the other hand, laws that contravene and prohibit them (e.g. Law 25268, art.5; Law 29763, DS 018- 2015-MINAGRI, DS 021-2015, art. 127,128,137.3 subsection a, b, c; Penal Code of Peru, Art 310). In addition, legal gaps and the lack of updated supranational and national regulations, and the legal bureaucracy mean that environmental processes and charges throughout the entire RBH are filed up to 100%, leaving many criminal behaviors that cause terrible wildfires unpunished (Manríquez and Rascón, 2020). Given this, the establishment of better criteria and goals of environmental protection in the technical part with clear definitions for different types of ecosystems is especially important.
Effectivity of the Huascaran National Park and Biosphere Reserve
Our results clearly shown that, after correcting by the amount of flammable area, the CZ has significantly less occurrence of AFD that the BZ and the TZ, indicating that the protection role of the HNP is being largely effective. Certainly, there are certain areas constantly affected over the years that we hypothesis is given to logistic difficulties to control remote areas where centers of control are absent. La Quebrada Cedros or the sector between the towns of Chacas and Huari, for example, are poorly patrolled areas with difficult access and it is where most of the AFD are concentrated. This contrasts strongly with areas such as Quebrada Llanganuco or Ulta where surveillance is constant, and the number of AFD is almost non-existent (see Fig. 1 and Fig. 4). The areas that make up the ZA and ZT do not have significant differences in the number of AFD, suggesting that the environmental policies for fire prevention and control implemented in these two areas are equally inefficient.
Fires during the 2020
The management of wildfires was especially difficult during 2020, a year where the COVID-19 pandemic not only caused many human losses but forced strict lockdowns that stopped many economic activities, including tourism. In 2020, many management activities of the HNP had to be suspended or modified, including the work with local communities and tourism, which represents the main economic income for many local people. It is certainly possible that this economic paralysis contributed to more people to shift to work the land, having made use of fire to clean unused areas for agriculture and livestock. Nevertheless, our results also show that 2020 had drier conditions that could have contributed to this high fire occurrence. Therefore, the pattern of fire in 2020 could be the result of a combined effect of dry weather conditions and an increased number of people redirecting their efforts to agricultural activities that involved the use of fire. Similar conclusion was made in Colombia, and other part of the globe (Amador-Jimenez et al. 2020).