Interference of bull thistle (Cirsiumvulgare) with growth of ponderosa pine (Pinusponderosa) seedlings in a forest plantation

1993 ◽  
Vol 23 (8) ◽  
pp. 1507-1513 ◽  
Author(s):  
John M. Randall ◽  
Marcel Rejmánek
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Seedling Growth ◽  
Ponderosa Pine ◽  
First Year ◽  
Relative Growth ◽  
Path Analyses ◽  
Second Year ◽  
Phosphorus And Potassium ◽  
Nitrogen Phosphorus

The biennial thistle Cirsiumvulgare (Savi) Tenore significantly reduced ponderosa pine (Pinusponderosa Dougl. ex Laws.) seedling growth during the second year of infestation but had insignificant effects in the first year when all thistles were in the rosette stage. Pine stem diameter relative growth rate was significantly negatively correlated with four different indices of thistle interference and with visual estimates of thistle cover. Total thistle density (adults + rosettes) within 2.0 m of target seedlings best explained differences in stem relative growth rate, but density of adults alone and visual estimates of thistle cover were nearly as good. Simple regressions indicated that soil moisture and pine predawn leaf water potential were significantly negatively correlated with thistle density and significantly positively correlated with stem relative growth rate, but multiple regressions and path analyses indicated that their effects on seedling growth were negligible relative to the other (unexplained) effects of thistle density. Foliar nitrogen, phosphorus, and potassium concentrations were not significantly correlated with thistle density and failed to explain differences in seedling growth. Although it remains unclear how thistles suppressed pine seedling growth, if these results hold true at other sites, plantation managers will have at their disposal relatively easy methods for assessing thistle interference.

Growth and seasonality of seedlings and juveniles of primary species of a cloud forest in northern Venezuela

1992 ◽  
Vol 8 (3) ◽  
pp. 299-305 ◽  
Author(s):  
Saúl Flores
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Forest Canopy ◽  
Slow Growth ◽  
Cloud Forest ◽  
Primary Root ◽  
Leaf Number ◽  
First Year ◽  
Leaf Production ◽  
Relative Growth

ABSTRACTThe survival, height and leaf production of seedlings and juveniles of Aspidosperma fendleri and Richena grandis were measured monthly for three years after germination. During the first year, some seedlings and juveniles of Aspidosperma fendleri were collected and the number of rootlets, the primary root length and the shoot: root ratio were determined.Both species show periodicity in growth but their relative growth rate differs between species. For Aspidosperma fendleri, the highest relative growth rate (0.313 y-1) was found for individuals grown under greenhouse conditions followed by individuals growing in an old forest gap (0.143 y-1) and finally individuals under the forest canopy (0.137 y-1). For Richeria grandis, the relative growth rate under the forest canopy was 0.261 y-1. Leaf production for Aspidosperma fendleri in the forest (natural conditions) was 4.39 total mean leaf number for five years and 5.46 total mean leaf number under greenhouse conditions. For Richeria grandis it was 5.34 mean leaf production for four years. The root: shoot ratio for Aspidosperma fendleri was constant during the observation year. Aspidosperma fendleri showed a lower number of rootlets than did Richeria grandis. There was an inverse relationship between growth and survival during the dry season. During this period, mortality was higher and the highest mortality occurred during the first year when the total relative growth rate was highest.Slow growth is evident in both species. This mechanism may represent an adaptive advantage to remain dormant until there is an opening in the forest canopy. Since the seeds of Aspidosperma fendleri and Richeria grandis are highly vulnerable to predators and pathogens, slow growth as seedlings and juveniles allows them to survive, and contributes to regeneration in cloud forest.

Growth Responses of Tanoak Sprout Clumps to Thinning

1994 ◽  
Vol 9 (4) ◽  
pp. 101-105 ◽  
Author(s):  
Timothy B. Harrington
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Growth Responses ◽  
Relative Growth ◽  
Vegetation Height ◽  
Crown Width ◽  
Lithocarpus Densiflorus ◽  
Mean Relative Growth Rate ◽  
Relative Cover ◽  
Second Year

Abstract At two sites in southwestern Oregon, stands of tanoak (Lithocarpus densiflorus) were thinned in the second year after sprouting (1983) to create relative covers of 25, 50, or 100% of that for unthinned stands. At one site, relative covers were replicated with and without suppression of understory vegetation. Height, crown width and dominant-stem diameter were measured annually on each of 135 sprout clumps of tanoak from 1983-1988. Reductions in relative cover caused a proportionate increase in mean relative growth rate (RGR) of tanoak; however, the effect of understory suppression was not consistent. Increases in RGR of individual clumps from thinning were considerably greater for crown width (73% and 43% for large and small clumps, respectively) than for height (28% and 22%). Predicted crown width of tanoak 6 yr after thinning and understory suppression was up to 46% greater than that of clumps in untreated stands. West. J. Appl. For. 9(4):101-105.

Sign in / Sign up

Export Citation Format

Share Document