Chusquea quila

Abstract: The bamboo Chusquea quila (Poaceae:Bambuseae) is the most abundant understory species ofNothofagus-dominated forests at low elevations inthe Chilean Lake District. Species of this genus strongly inhibit theestablishment and growth of tree species, especially those of the genusNothofagus. At intervals of many years, this bambooflowerssynchronously and dies, creating large-scale disturbances. The mainobjective of this study was to determine the influence of bamboo dieback ontreeregeneration, especially of shade-intolerant species. The forest studiedis a remnant stand of old-growth forest dominated by emergent individualsof N. obliqua and Eucryphiacordifoliawhich project about 10 m above a main canopy formed byAextoxicon punctatum, Laureliaphilippiana, and Podocarpus saligna. Treeseedlings that established prior to bamboo dieback were recorded in six gapsdensely covered by bamboo. After the dieback event in the early 1990's,recruitment, height growth and survivorship were monitored in four gaps duringtwo growing seasons. After the synchronous mass flowering and death ofChusqueaquila, both reorganization of advance regeneration and new seedlingrecruitment were observed in gaps. The advance regeneration consisted mainly ofthe shade-tolerant species A. punctatum,L. philippiana, and Amomyrtus luma.These species together with E. cordifolia accounted forover 90% of the total individuals in gaps. During the following twoseasons, c. 40% of the advance regeneration either died or was damaged.Root suckers of E. cordifolia and L.philippiana were taller and grew faster than the seedlings of otherspecies. Nothofagus obliqua was unable to establishadvanceregeneration in gaps formerly dominated by bamboo. New recruitment resulted inthe synchronized establishment of treeseedlings, especially less shade-tolerant species such as N.obliqua, Aristotelia chilensis,Rhaphithamnus spinosus, and E.cordifolia. These species recruited into the gaps almost entirelyduring the first season right after the bamboo dieback. However, by the end ofthe second season, these species had a lower density due to a combination oflower recruitment rate, shortened recruitment period, and greater mortalityratecompared to the shade-tolerant species. New bamboo seedlings grew fasterand were more abundant than tree seedlings, except for root suckers (bothnew establishment and advance regeneration) of E.cordifolia which is more likely to successfully recruit into thecanopy. Seedlings of N. obliqua compete poorly with bambooseedlings; its successful recruitment may require bamboo flowering coincidentwith a mast seed year for the tree species.

Abstract: The gap dynamics of two Nothofagus pumilio lenga stands have been investigated. We evaluated and compared tree diameter distributions, spatial patterns, tree fall and gap characteristics and regeneration responses in gaps in two old-growth forests of Nothofagus pumilio in Southern Chile Shangri-La: 36°60' S, 71°30' W; Reserva Coyhaique: 45°52' S, 72°00' W. In addition, we describe relationships between gap size and regeneration characteristics. We detected some differences in tree and sapling densities between sites. The causes of gap formation and the gap size distribution, mean gap area, and gap fraction were similar, but gap abundance was different at the two sites. The Reserva Coyhaique site had 15 gaps/ha compared to 10 gaps/ha for Shangri-La. Sizes of clumps of trees were within the range of sizes of canopy gaps at both sites. The density of saplings was higher in gaps than under closed forest at R. Coyhaique, but not at Shangri-La. We found that sapling densities were unrelated to gap size in both sites. The lower sapling density in gaps at Shangri-La might be explained by the presence of Chusquea quila, a competitive pioneer bamboo species. The height increment was related to gap size at ShangriLa, but not at R. Coyhaique. Gap size itself does not account for all the variation in recruitment performance in these Southern beech stands.

Abstract: Polymers of renewable origin have aroused great interest among researchers due to their sustainable, environmentally friendly nature. This work presents a biopolymer called bio-tissue, as it is created by electrospinning. This bio-tissue was formed with a polymer matrix of cellulose acetate (CA) reinforced with crystalline cellulose (NCC) derived from an autochthonous Chilean bamboo species of no commercial value which is considered a pest, Chusquea quila or quila. Bio-tissues were produced with three concentrations of NCC (1, 5 and 10% as a dry weight proportion of cellulose acetate) and their technological potential as an interior coating in small constructions was assessed. The morphology of the bio-tissues showed that the CA nanofibers containing NCC were of better quality and more uniform diameter than pure CA. The thermal profile showed that the highest concentration of NCC (10% as a dry weight proportion of cellulose acetate) induced earlier degradation; it was less thermally stable and decomposed at lower temperatures. The bio-tissue with 5% as a dry weight proportion of cellulose acetate showed the greatest resistance to traction with a break-point of 30 MPa and an elasticity module of 1.597 MPa. Finally, it was shown that the permeability to water vapour, oxygen and carbon dioxide was low, allowing regulated passage of these molecules. These results show the feasibility of using cellulose nanofibers as a reinforcement in polymer matrices; this could have various applications in fields ranging from the construction industry to food packaging.