Pinus Pseudostrobus Lindl Research Articles

First Report of Arceuthobium vaginatum subsp. vaginatum on Pinus pseudostrobus.

Arceuthobium vaginatum (Willd.) Presl subsp. vaginatum (family Viscaceae) is the most widespread and common dwarf mistletoe in Mexico (2). Although most dwarf mistletoes are considered to be relatively host-specific parasites, this species has the broadest host range found in the genus. It has been reported to infect 13 species of pines (Pinus spp., family Pinaceae) (2). Pinus pseudostrobus Lindl. is a common pine within the geographic range of A. vaginatum and has been reported as possibly being immune to this mistletoe (2). However, we have found a location in the Sierra Madre Oriental, Nuevo Leon, Mexico where A. vaginatum subsp. vaginatum is severely parasitizing P. pseudostrobus. The stand of infected P. pseudostrobus is located approximately 3 km east of Laguna de Sanchez(25°19'42″N, 100°15'45″W, elevation 1,950 m). Several hundred P. pseudostrobus are infected at this location; several trees in the stand have one or more dwarf mistletoe infections on nearly every branch and many trees have bole infections. P. pseudostrobus is the only pine growing at this locality, and the extent of infection on this pine clearly indicates it is highly susceptible to A. vaginatum subsp. vaginatum. Hawksworth and Wiens (2) based their tentative classification of P. pseudostrobus as immune to A. vaginatum subsp. vaginatum on observations of uninfected P. pseudostrobus growing near severely infected pines in central Mexico. The discrepancy between the susceptibility of P. pseudostrobus in central Mexico and in Nuevo Leon may be related to the different taxonomic classifications afforded these populations by different pine taxonomists. For example, Perry (3) considers the populations of P. pseudostrobus growing in Nuevo Leon to represent P. pseudostrobus forma megacarpa Loock, while Farjon and Styles (1) treat these populations as typical P. pseudostrobus. Whether the high level of susceptibility of the P. pseudostrobus population near Laguna de Sanchez indicates these populations are taxonomically distinct from typical P. pseudostrobus needs further study, but the severe infection we observed in Nuevo Leon clearly demonstrates that P. pseudostrobus should be reclassified as a principal host of A. vaginatum subsp. vaginatum in northeastern Mexico. Specimens of A. vaginatum subsp. vaginatum on P. pseudostrobus have been deposited at the Deaver Herbarium, Northern Arizona University, Flagstaff (Accession No. 76455). To our knowledge, this is the first report of A. vaginatum subsp. vaginatum on P. pseudostrobus. It should also be noted that the population of A. vaginatum subsp. vaginatum near Laguna de Sanchez is 150 m below the lower elevation limit previously reported for this dwarf mistletoe in Mexico (2).

Interception loss, throughfall and stemflow chemistry in pine and oak forests in northeastern Mexico.

Interception loss, gross precipitation, throughfall and stemflow solution chemistry beneath pine (Pinus pseudostrobus Lindl.), oak (Quercus sp.) and pine-oak natural forest canopies in northeastern Mexico were measured. Coefficients of variation for throughfall were 12% in pine and oak canopies and 17% in the mixed pine-oak canopy. The variability of stemflow averaged 66, 126 and 73% for pine, oak and the mixed pine-oak canopies, respectively. Linear regression analysis of net versus gross precipitation for the three canopies showed highly significant correlations (r = 0.974-0.984). Total precipitation during the experimental period was 974 mm and estimated interception loss was 19.2, 13.6 and 23% for the pine, oak and pine-oak canopies, respectively. Stemflow did not occur following rainfall events of less than 4 mm and, in all canopies, stemflow represented a minimal proportion of gross precipitation (0.60, 0.50 and 0.03% for pine, oak and pine-oak, respectively). Throughfall pH in pine (6.2), oak (6.3) and pine-oak (6.3) canopies was significantly more acidic than gross precipitation (6.6). Stemflow pH ranged from 3.7 (pine) to 6.0 (oak). The pine-oak canopy registered the highest throughfall and stemflow electrical conductivities, 104 and 188 microS cm(-1), respectively. Net nutrient leaching of K, Mg, Na, Fe, Mn and Zn was significantly higher from the pine-oak canopy than from the pure pine and oak canopies. Mean depositions of Ca and Cu in throughfall behaved similarly among the three types of canopies. A greater proportion of Zn in gross precipitation was absorbed by the oak canopy than by the pine and pine-oak canopies. Enrichment factors beneath the pine-oak canopy relative to gross precipitation varied from 1.2 to 3.2 for macro-nutrients (Ca, K, Mg and Na) and from 1.4 to 3.1 for micro-nutrients (Cu, Fe, Mn and Zn). Stemflow depositions of Ca, K, Mg and Cu were higher in the pine-oak canopy, whereas stemflow depositions of Na, Fe, Mn and Zn were higher in the pine canopy.

Construction of yield tables based on temporary sample plots

In this work a methodology for the construction of yield tables based on data of temporary sample plots, stem analysis, and measurements on individual trees is presented. The method was developed in Mexico using as example the species Pinus pseudostrobus Lindl. The procedure employed is based on the calculation of the total yield according to Magin's Method. The relationships between the most important stand parameters were determined using regression equations.