The effects of gap size and age on natural regeneration of Picea mongolica in the semi-arid region of Northern China

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

“…The numbers of A. faxoniana seedlings in gaps without bamboos (A-gaps) significantly decreased with the increases of gap size. In general, in large gaps the establishment of tree regeneration will be limited by strong light radiation, high temperature and evaporation, and subsequently low soil water availability (Bullock, 2000;Zhang et al, 2013). However, A. faxoniana seedlings in gaps with bamboos (in Sn-and Ss-gaps) were insensitive to increased gap size, which may also result from the scarcity of A. faxoniana seedlings.…”

“…The sizes of sampled plots in small gaps varied from 4 m 2 to 16 m 2 , in medium-size gaps varied between 16 and 49 m 2 , while in large gaps varied between 49 and 100 m 2 (Zhang et al, 2013). Longitude, latitude, altitude, slope and aspect of each gap were recorded at the gap center.…”

“…Moreover, large gaps reduce soil moisture and raise the air temperature, and therefore increase the mortality of young seedlings (Darabant et al, 2007). For another, gap age, which is known as gap phase or temporal heterogeneity of gap disturbance, directly relates to the microsite situations and consequently influences on the establishment and growth of understory vegetation (Barik et al, 1992;Chandrashekara & Ramakrishnan, 1994;Kirchner et al, 2011;Kinny et al, 2012;Zhang et al, 2013). With the gap environment develops, the gradually lower light levels would lead to inter-species …”

Effects of gap microsites and bamboo onAbies faxonianaregeneration in a subalpine forest, China

“…In each gap, one plot in each quadrant (north, west, south, and east) and one another plot at the gap center were set. The sizes of the plots in gaps varied between 4 and 100 m 2 , ranging from 4 to 16 m 2 for small-sized gaps (50-200 m 2 ), from 16 to 64 m 2 for medium-sized gaps (200-1000 m 2 ), and from 64 to 100 m 2 for large-sized gaps (1000-2000 m 2 ; Zhang et al 2013). The longitude, latitude, altitude, slope, aspect, size, and age of each gap were recorded at the gap center.…”

“…The physical characteristics of gaps, such as gap size and age, directly affect the microclimate in gaps and contribute to the heterogeneity of microsites (Indra & Per 2009; 'microsite' in this work is understood as substrates where tree regeneration growing). For instance, gaps with various sizes may lead to distinct differences in seedling amounts and coexistence patterns among species (Caccia et al 2009); with gap age increases, the understory light intensity decreases, the recruitment patterns of trees species change, and thus, species diversity varies with time (Zhang et al 2013). Furthermore, under the influence of gap size and age, microsites and understory vegetation often exert important effects on the regeneration patterns of tree species (Taylor et al 2006).…”