Plant Life of Paricutin Volcano, Mexico, Eight Years After Activity Ceased

• Published in: The American midland naturalist 1963-01, Vol.69 (1), p.38-68
• Main Author: Eggler, Willis A.
• Format: Article
• Language: English
• Subjects: Ash cones; Lava flows; Mosses; Nitrogen; Plants; Shrubs; Trees; Volcanic ash; Volcanic ash soils; Volcanoes
• ISSN: 0003-0031; 1938-4238
• DOI: 10.2307/2422843

Paricutin Volcano, Michoacan, Mexico, began erupting on February 20, 1943, and ceased on March 4, 1952. The present report covers observations made in 1959 and 1960 on plants of the area. By 1959 former forests in the volcanic area were usually well along toward being freed of ash, except where enough pine trees had survived to supply a blanket of needles which stopped erosion. Where ash was removed prevolcanic plants resumed growth, and new ones became established. Old fields were more nearly level than forested areas and they were relieved of much less of their ash mantle. Plants never invaded old fields where any ash mantle remained, except where old soil or animal droppings had improved conditions. But plants were also able to get started if other plants already grew there. Primary succession had begun on the oldest lava flows in 1950. By 1960, 33 species of plants were growing on the lava flows. There was a dense shrub and herb growth on certain hornitos near the cinder cone. Vascular plants were first observed on the cinder cone in February, 1957, when two species were seen. Twenty-eight species were present by 1960. Disseminules of nearly all pioneer plants on the lava flows, hornitos, and cinder cones are known to be wind carried. Only two have fleshy fruits and were probably disseminated by birds. Determination of nitrogen content of ash samples collected from ash fields, lava flows, and the cone indicated the following. There was always at least a minimal amount of nitrogen in the samples analyzed, probably enough to nourish plants. The lowest value was 15.2 ppm; the highest 277.7 ppm. A significant part of the nitrogen was in the form of soluble compounds, as indicated by increasing concentration with greater depth in areas without plants. Where plants were present the nitrogen content near the surface was significantly greater than at greater depths. This was true under mosses as well as under vascular plants. This indicated that plants here concentrate nitrogen compounds in upper soil layers.