Mexico: Adaptive Restoration of Arenales, Paricutin Volcano, Michoacan

Project Stage:
Completed

Start Date:
2001-01-01

End Date:
2006-01-01

Primary Causes of Degradation

Degradation Description

When Paricutin erupted it drastically altered the lands of the area, especially the corn field in which it appeared. The eruptions resulted in areas that were under cultivation or barren at the time being covered entirely by tephra deposits. In those areas with canopy cover the tephra mixed with leaf litter and seeds, while the canopy offered sufficient shadow to allow for both plant germination and survival. In the arenales the tephra deposits were as shallow as 2 cm to as deep as 2 m and their black color because of their basaltic origin contributed to surface and subsurface temperatures as high as 70 degrees centigrade during the peak of the dry season. Combined with the low nutrient levels in the tephra the depth to fertile soil is an excluding factor for plant establishment.

Reference Ecosystem Description

The communal lands of Communidad Indigena de Nuevo San Juan Parangaricutiro have a complex disturbance history. Prior to the eruption of the Paracutin volcano in 1943, the lands affected most by the arenales today were subsistence maize fields. Research conducted in the area in the intervening years has shown that those areas which had non-agricultural plant cover prior to the eruptions were the most responsive after the eruptions to natural regeneration.

Project Goals

The community’s dependence on timber production and subsistence agriculture necessitated that an effort be made to restore the arenales, which were totally unproductive. Given the reliance on timber the project was instigated to evaluate the potential for restoring those economically important timber species.

Monitoring

The project does not have a monitoring plan.

Stakeholders

The communal lands of the Communidad Indigena de Nuevo San Juan Parangaricutiro (CINSJP) include 11,694.5 hectares that are managed for sustainable timber production, multiple forest uses, and subsistence agriculture. Scientists have been involved in the formulation of natural resource management policies in the communities since the late 1990s, when an extensive project evaluated the entirety of the community’s land with an eye toward biodiversity conservation within the context of sustainable timber production. The present project was an effort to restore those specific arenales still unproductive.

Description of Project Activities:
The approximately 12-ha experimental site is elongate, following an east - west direction, with a 2 - 3% north-facing slope. At the time of the eruption, it was an agricultural field, according to a local farmer. The experiment consisted of six blocks (A - F). Blocks A, B, and C were protected by one fence, and blocks D, E, and F were within another fence, to exclude cattle. It was not possible to include all the six blocks in one fence because several heavily used trails cross the area. Each block consisted of 32 plots of 1.96 m2, for a total of 192 plots on the entire experimental site. Project managers designed a two-factor experiment (presence or absence of L. elegans and presence or absence of pine-bark mulch). They then planted P. pseudostrobus on the plots for a total of four treatments: control (two pine plants per plot), presence of L. elegans (two pine plants surrounded by four lupine plants), presence of pine-bark mulching (a 4-cm-deep layer covering the plot around two pine plants), and presence of L. elegans and pine bark (two pine plants surrounded by lupines and the plot covered by bark). Personnel from the Technical Forestry Office of the CINSJP planted two 8-month-old plants of P. pseudostrobus in each of the 192 plots (32 for each block) during the second week of July 2002. Once the plantation was finished, four 2-month-old L. elegans plants were planted in plots chosen for the presence of lupines and bark laid on the corresponding quadrats, for a total of 48 replicates per treatment. Pine plants were evaluated on three occasions: (1) in August 2002 for initial height; (2) after the first growing season (June 2003) for survival and growth; and (3) after the growing season (June 2004) for survival and growth on blocks A, B, and C. Blocks D, E, and F were not evaluated in June 2004, except to record 100% mortality of pines due to heavy run-off. Lupinus elegans plants were evaluated for survival and growth monthly, for a total of nine times after setting up the experiment. In each visit, survival, height, type of damage (herbivory, frost damage), and flowering were recorded. The last monthly visit was in April 2003, when there were no surviving individuals. Finally, they visually estimated the percentage of mulch that remained on the plots at the end of the 2002 wet season. Air and tephra temperatures (4 cm below the surface) were recorded hourly with data loggers (Hobo H01-001-01; Onset Computer Corporation, Pocasset, MA, U.S.A.). to further explore how the time of survival of lupines differed between presence or absence of pine-bark mulching in both the experiments (the field experiment and the follow-up experiment). Follow-Up Experiment A follow-up experiment determined the effect of contour trenches to reduce run-off and fencing to reduce damage by small rodents on L. elegans survival. Greenhouse-propagated L. elegans plants were planted in four blocks, each with 100 plants. Two blocks were protected from small rodents by fencing with chicken wire. Eight monthly visits allowed registering survival by month and height of surviving plants at the end of the experiment; also, the time of flowering and seeding was recorded.

Ecological Outcomes Achieved

Eliminate existing threats to the ecosystem:
Harsh environmental conditions in tephra deposits limit native plant establishment in our field site and other tephra-covered areas. The main limiting factor for pine survival appears to be high substrate temperature. In this project, experiment mortality occurred almost exclusively when substrate temperature approached 60°C during the dry season. Pine bark used as mulch was effective in increasing pine survival. After one growing season, survival rates of pine plantings protected by mulch were 46.5% vs. 21.8% without mulch. Survival with pine-bark mulch was comparable to the national average of 50% for Mexico after 1 year of planting under less stressful conditions, such as abandoned agricultural fields. Furthermore, mulch provided better growing conditions for pine plants, as shown by comparing heights after two growing seasons. Nevertheless, in the field experiment, the effectiveness of pine-bark mulch was limited by run-off, which removed large patches of the protective mulch. The follow-up experiment, protected from run-off with contour trenches, suffered less mulch removal. Thus, contour trenches can be useful in unconsolidated substrates such as tephra of basaltic origin if maintenance is provided. Lupinus elegans plants grew poorly due to damage by small rodents during the early-growth stages, by run-off that flattened plantings, and frost damage at the end of the growing season. Herbivory has been shown to be a limiting factor for plant survival under restoration conditions in many sites, with overall damage of 64% for tropical forest restoration in Costa Rica and of 78% in seedlings of Quercus rugosa in restoration sites near Mexico City. In the field site, herbivore damage decreased with increased size of L. elegans, as has been found for oak seedlings and Senecio praecox saplings under restoration conditions. The follow-up experiment showed that fencing can eliminate damage by small herbivores. Frost damage occurred because of the exposed nature of the site; as canopy cover increases, frost damage might be reduced. In the field site, L. elegans behaved as an annual species, setting seed at the end of the growing season and then dying, despite being a short-lived perennial. This behavior was probably a response to the site's harsh conditions. Others have also reported slower growth of native shrub species on tephra deposits compared with preeruption soils. Because of their small size and short survival times, we did not detect an effect of lupines on pine plantings. The role played by lupine species in the establishment of native vegetation on tephra deposits is controversial. Plantings introduced to bare tephra experience low soil moisture and high temperatures until the beginning of the wet season when plants would normally establish. Our results demonstrate that mulching can overcome some of the limitations to establishment that are imposed by tephra deposits.

Factors limiting recovery of the ecosystem:
The project was considered to bean an adaptive restoration of agricultural fields covered by volcanic ash because it illustrated how a complex series of events can cause unexpected outcomes and present further challenges for the restorationist. At the site, dry years have been followed by several mild years, and plant survival in the restoration effort varies accordingly. Plant mortality can be particularly high during dry years; the intensity of high temperatures during the dry seasons that have followed restoration plantings is unpredictable. Other limitations to plant establishment include herbivores and run-off damage to small plants and seedlings. In these experimental restorations, smooth-barked Mexican pine plants protected with mulch had 80% survival rates during mild years and 46% survival rates during the hottest year"”16% higher than the average for reforestations with this species in Michoacán. Age at planting is also an important variable that can increase pine survival. In these restorations, 18-month-old plants had significantly higher rates of survival than younger plants. Low pine survival on restoration sites represents substantial economic losses for the community and can also create conditions that worsen the restoration scenario. Then there is the problem of Hierba de golpe (Eupatorium glabratum), which is a fast-growing native species than can reach more than 1 m in height after the first year. Hierba de golpe is present in disturbed areas below the tree canopy and other open areas. This species is dominant in the arenales together with false arnica (Senecio stoechadiformis) and willow ragwort or pescadito (Barkleyanthus salicifolius). The spatial pattern of existing hierba de golpe plants is striking because shrubs of this species grew interspaced 2 m apart in a regular grid pattern. Monthly visits by the project team since 2002 provided the evidence needed to explain the existence of these hierba de golpe "plantations." Hot years causing high pine mortality also trigger massive flowering and seeding of hierba de golpe plants. The pine plants that died as a result of the hot dry year made favorable sites for hierba de golpe seed accumulation and seedling growth because of the litter and fertile nursery substrate left by the dead plants. Under such favorable conditions hierba de golpe seeds can germinate and grow in areas where the volcanic ash layer would otherwise prevent establishment. Although flowering in this species typically occurs during the peak of the dry season, from late March to May, it is common for many of the plants in a population not to set flower every year. When conditions are favorable, however, massive blooming occurs and large quantities of wind dispersed seeds are produced. When mass flowering happens, large areas get covered with seeds that accumulate in small sites protected from the wind, such as stems, rocks or the dead pine trees planted for restoration. Hierba de golpe seeds sometimes accumulate to up to half a centimeter thick. These seeds can germinate immediately when the first rains moisten the soil, usually during June. Other efforts to reclaim arenales have been affected by hierba de golpe invasions. Peach orchards have almost failed completely because although many peach trees germinated, many hierba de golpe plants became established in the sheltered pit dug for each peach plant and out competed the peach trees. Hierba de golpe is undesirable because few natives establish under this species' canopy, particularly tree species. Where native species have a chance to establish themselves, hierba de golpe normally does not exceed 30% of any patch canopy cover. The other shrubs common in the arenales, false arnica and willow ragwort, do not prevent native species establishment under their canopies. Once established, hierba de golpe is hard to eliminate and requires extraction along with the top layer of volcanic ash using heavy machinery. This strategy, although expensive, is efficient. Experimental restoration plots show high survival and growth rates for the native pine species that dominate the forests in the region (smooth-barked Mexican and Montezuma pines), and native shrubs and forbs have colonized the area by themselves.

Socio-Economic & Community Outcomes Achieved

Economic vitality and local livelihoods:
Mexico is known to have 10% of the biodiversity of the world on lands that are communally owned and managed. The importance then of integrating biodiversity conservation with sustainable uses of the land cannot be understated. This project sought to provide methods of restoration for a community that relies heavily on timber production for its annual income. The results showed the efficacy of mulching on the survival of transplanted trees, a technique that has potentially wide application as the mulch is a byproduct of the timber milling operations of the community. This deepens the linkage between sustainable forest management and restoration.

Long-Term Management

The community has become a model of ecologically responsible development. The larger project to educate and equip the community with the necessary tools, such as GIS, ecological science workshops, and biological inventories of their work, has resulted in a community highly attuned to their role as conservators of biological diversity. The community has established a group that is responsible for land management decision-making and in the process they have integrated the tools provided by GIS and a deeper scientific foundation of their work.

Sources and Amounts of Funding

Restoration research began as a collaborative effort between the researchers and the community in 2001, funded by a gift from Ed Weigner through the Institute for Environmental Studies of the University of Wisconsin – Madison. The community provided pine plants and labor. The research grant provided monitoring equipment and other materials. Subsequently, the costs related to ongoing research have been covered by the Mexican Science Council (CONACYT), and the community continues to provide plants, materials, and labor.

Other Resources

Lindig-Cisneros, R., S. Galindo-Vallejo and S. Lara-Cabrera. 2006. Vegetation of tephra deposits 50 years after the end of the eruption of the Paricutín volcano, México. Southwestern Naturalist 51:455 – 461.

Lindig-Cisneros, R. 2007. Unexpected Outcomes and Adaptive Restoration in Michoacan, Mexico: A cautionary Tale from Sites with Complex Disturbance Histories. Ecological Restoration. 25(4):263-267.

Velázquez, A., G. Bocco and A. Torres. 2001. Turning scientific approaches into practical conservation actions: The case of Comunidad Indígena de Nuevo San Juan Parangaricutiro, Mexico. Environmental Management 27:655 – 665.

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