Necrotic spots induced by simulated acid rain on needles of Abies balsamea saplings

Abstract

Simulated acid rain (SAR) of pH 2.6, 3.6 and 5.6 (control) was applied to Abies balsamea (L.) Mill, saplings at 2-week intervals for 3 years. Ambient precipitation was excluded from the trees during this period. Eight to dark brown necrotic spots along the midribs of needles, 0.1 to 0.5 mm in diameter and sometimes having a white center, were associated with the most acidic (pH 2.6) SAR treatment. These spots appeared over a significantly (p = 0.05) larger area of the foliage in the pH 2.6 treatment than in controls (pH 5.6). Needles that received SAR of pH 3.6 had intermediate numbers of spots. The spots persisted for at least 1% years after cessation of SAR application. Needle retention, needle lengths, and the occurrence of epicormic shoots and the needle rust caused by Uredinopsis longimucronata FauU were not significantly (p = 0.05) affected by the SAR treatments. Needle retention tended to be lessened by the most acidic (pH 2.6) SAR treatment. The occurrence oi Eophodermium piceae (Fuckel) Hohnel needle cast was significantly lower in the middle tree sections of the pH 5.6 and 3.6 treatments than in the pH 2.6, drought and ambient treatments. Damage by naturally occurring insects was negligible, and was not related to the SAR treatments.

The Creation of Alternative Stable States in the Southern Boreal Forest, Québec, Canada

“…Zonal disks from Lophodermium piceae (Fckl.) Hoehn., a needle fungus found on several spruce and fir species (Darker 1932, Gourbière et al 1986, Whitney and Ip 1990, Osorio and Stephan 1991, Magan and Smith 1996, were also counted. These disks are resistant to decomposition thus providing a means to enumerate the presence of the species after the needle it had previously colonized has totally decomposed CREATION OF ALTERNATIVE STABLE STATES (J. P. P. Jasinski and S. Payette, unpublished manuscript).…”

Holocene occurrence ofLophodermium piceae, a black spruce needle endophyte and possible paleoindicator of boreal forest health

“…L. piceae is a needle fungus found on several different spruce and fir (Abies) species (Darker, 1932;Gourbière et al, 1986;Magan and Smith, 1996;Osario and Stephan, 1991b;Sharma and Sharma, 1981;Whitney and Ip, 1990). The life cycle of L. piceae has been described by Osario and Stephan (1991b) in 6 stages: (1) spruce needles are infected with ascospores, (2) the fungus lives as an endophyte in the green needle for several years, (3) conidiomata and conidia form but are not relevant for further infection of needles, (4) ascomata form on retained and fallen needles, (5) ascomata ripen and release spores infecting more needles, and (6) empty fruit bodies and needles decompose in the forest litter.…”