Seedling Survival and Growth of Three Forest Tree Species: The Role of Spatial Heterogeneity

Abstract

Spatial heterogeneity in microenvironments may provide unique regeneration niches for trees and may promote forest diversity. We examined how heterogeneity in understory cover, mineral nutrients, and moisture and their interactions with canopy gaps contribute to the coexistence of three common, co‐occuring tree species. We measured survival and height growth of 1080 seedlings of Acer rubrum (red maple), Liriodendron tulipifera (yellow poplar), and Quercus rubra (red oak) that were planted in one of five understory treatments: removal of understory vegetation, trenched, trenched plus removal of understory vegetation, fertilization, and a control. Understory treatments were replicated in 12 paired gap and canopy environments. Survivorship varied among species, with Q. rubra having the highest probability of surviving beyond the 1135‐day experiment (probability = 0.64), followed by A. rubrum (probability = 0.27) and L. tulipifera (probability = 0.07). Although canopy gaps and understory treatments had large effects on survivorship, species survival rankings changed little across microenvironments; Q. rubra had the highest survival in all microenvironments. In contrast to survival, L. tulipifera had a relative growth rate for height that was three times greater than that of A. rubrum and Q. rubra in high‐resource microenvironments. There was broad overlap among species in relative growth rates in the remaining seven microenvironments, with no clear top‐ranked species. Differences in seedling growth and survival across these 10 microenvironments may contribute to the coexistence of two of the three species studied, L. tulipifera and Q. rubra, but not A. rubrum. Q. rubra had higher survival than A. rubrum and L. tulipifera in all microenvironments, but L. tulipifera tended to grow faster than A. rubrum and Q. rubra in high‐resource microenvironments. Despite the generally poor performance of A. rubrum, it was the only surviving species in some quadrats at the end of the experiment, indicating that stochastic effects, in conjunction with broad niche overlap, may also contribute to species coexistence. The importance of stochastic effects will probably increase when differential fecundity across these three species is considered because the high fecundity of A. rubrum offsets survival and growth disadvantages of its seedlings through their greater total abundance.

Experimental biogeography: the role of environmental gradients in high geographic diversity in Cape Proteaceae

“…P. subvestita had signiWcantly lower survival than the other species (two-tailed t-tests, Bonferroni correction). Variation in survival among replicate plots within sites was substantial, consistent with the usual pattern in Weld studies of plant establishment, reXecting the eVects of environmental variability at the smallest spatial scales (Beckage and Clark 2003;Ibanez et al 2007). …”

“…Mortality of the transplanted seedlings was analyzed using parametric survival analysis, which can accommodate the interval-censored data generated by periodic site visits over the 2 years of the experiment (Beckage and Clark 2003). To visualize survival curves, nonparametric Kaplan-Meier estimates of the survival curve for each species and site were obtained (Turnbull 1974;Venables and Ripley 2002).…”

“…To visualize survival curves, nonparametric Kaplan-Meier estimates of the survival curve for each species and site were obtained (Turnbull 1974;Venables and Ripley 2002). For formal comparison of treatment eVects, parametric survival functions were Wtted to the survival data for each species/site combination (Beckage and Clark 2003).…”

Effects of gap size, gap age, and bamboo Fargesia denudata on Abies faxoniana recruitment in South-western China

“…Bamboos, for instance, greatly inhibit tree seedlings and saplings in many forests in Japan (Nakashizuka, 1989;Yamamoto, 1995), China (Taylor et al, 2006), Chile (Veblen, 1989), the United States (Harmon & Franklin, 1989), etc. Because of their rapid clonal growth and high degree of dominance (Nakashizuka & Numata, 1982a, b;Veblen, 1982;Lusk, 2001;Wang et al, 2006), bamboos largely reduce the underneath light availability, as well as the nutrients and water in soil (Rao & Ramakrishnan, 1989;Singh & Singh, 1999;Beckage & Clark, 2003;Takahashi et al, 2003;Embaye et al, 2005;Tripathi et al, 2005;Montti et al, 2011), and therefore, diminish the seedling abundance of the surrounding trees (Nakashizuka, 1988;Beckage et al, 2000;Caccia et al, 2009;Larpkern et al, 2010). Although much relevant research has been done, it will be interesting to add the influence of gap characteristics into the relationship between bamboos and tree regeneration.…”

Efeitos dos ninhos de Atta laevigata (Fr. Smith, 1858) (Hymenoptera: Formicidae) sobre a vegetação do cerrado

“…Ecólogos têm frequentemente considerado em separado o efeito da heterogeneidade espacial e temporal na emersão e sobrevivência de mudas. Estudos remetem à influência da variação espacial no regime de luz, quantia de resíduo (lixo) e características físicas e químicas da superfície do solo sobre o recrutamento e estabelecimento de mudas (BECKAGE;CLARK, 2003). No entanto, a heterogeneidade espacial e a temporal talvez atuem juntas para afetar a emersão e sobrevivência de mudas e, consequentemente, a composição da comunidade.…”