Abstract:We studied the effects of five thinning treatments (T1 = 5.5, T2 = 11, T3 = 16.5, T4 = 22.5 and T5 = 28.5 m(2) ha(-1) basal area under bark) x two fertilizer treatments (F0 = unfertilized and F1 = fertilized with 400 kg ha(-1) N plus 229 kg ha(-1) P) on growth and water relations of pole-sized Eucalyptus marginata J. Donn ex Sm. trees growing in southwestern Australia. Thinning reduced leaf area index (LAI) from 2.1 in the T4 and T5 treatments to 0.8 in the T1F0 treatment. Fertilizer had no effect on LAI in th… Show more
“…Water and nutrients (particularly nitrogen (N)), as the essential resources to plants, are two of the most important factors controlling tree growth [1,2] and productivity [3], and there are interactions between them. Matching N supply to plant water availability is essential for a successful crop yield [4,5].…”
“…Water and nutrients (particularly nitrogen (N)), as the essential resources to plants, are two of the most important factors controlling tree growth [1,2] and productivity [3], and there are interactions between them. Matching N supply to plant water availability is essential for a successful crop yield [4,5].…”
“…Second, young trees in revegetated areas are unlikely to provide the large fruit crops that older trees in unmined forest can. Additionally, high tree stem densities -typically much higher in revegetation than in unmined forest -can limit tree growth rates (Stoneman et al 1997;Grigg and Grant 2009) and may also constrain flowering and fruit crops (Arista 1996;Williams et al 2006). Glossy black cockatoos (Calyptorhynchus lathami) preferentially feed in trees with large fruit crops, probably because it is more energy efficient (Chapman and Paton 2005); so, the same may hold true for our study species in the jarrah forest.…”
Section: Successional Changes In Feeding Activitymentioning
Context: Provision of key habitat resources is essential for effectively managing species that have specific ecological requirements and occur in production landscapes. Threatened black cockatoos in the jarrah (Eucalyptus marginata) forest of Western Australia have a wide range, so their conservation requires support from all land tenures, not just reserves. Mining in the jarrah forest temporarily removes cockatoo feeding habitat, so it is important to understand how cockatoos exploit revegetated areas for food resources.
Aims:We aimed to determine whether there were successional patterns in cockatoo feeding activity in revegetation aged from 4 to 23 years at three mine sites in the jarrah forest in south-western Australia.
Methods:We surveyed 232 plots in revegetation to document (1) structural and floristic variation in vegetation across mine sites and revegetation ages, (2) differences in cockatoo feeding activity across mine sites and revegetation ages on the basis of feeding residues and (3) any edge effect reflecting preferential use of vegetation at the interior or exterior of mine pits. We also documented the frequency of occurrence of cockatoo food plants and feeding residues in 480 plots in unmined forest to compare with revegetated areas.Key results: Marri (Corymbia calophylla) and jarrah were commonly consumed in unmined forest and Banksia and Hakea species were also fed on to a lesser extent. Revegetated mine pits provided food within 4 years and continued to do so up until the oldest plots studied (23 years). The relative importance of food plants shifted from proteaceous species in young revegetation to myrtaceous species in intermediate to older revegetation. However, extent of feeding on myrtaceous species in older revegetation did not equate to feeding rates in unmined forest, with lower frequencies recorded in revegetation.Conclusions: Black cockatoos fed in revegetation at all three mine sites, despite variations in vegetation age, structure and floristics. Feeding on proteaceous and myrtaceous food plants occurred within 4 and 7 years of revegetation being established, respectively, indicating that some food resources are restored quickly after mining disturbance of the jarrah forest.
Implications:Our results emphasise the importance of monitoring fauna recolonisation over appropriate time scales, to understand how successional processes in revegetation influence fauna population persistence in production landscapes.
“…Measurements began right after thinning conducted every 45 days during 2 years following thinning. Sample collection and treatment was applied following (Stone et al 1999). It began two hours prior to dawn and ended before dawn.…”
Section: Water Relationsmentioning
confidence: 99%
“…First, temporal variation in individual tree parameters, e.g., tree leaf area (LA tree ), BAI tree as well as tree mortality rate, was all associated with inter-year fluctuations in rainfall amount (Dorman et al 2013;Tesemma et al 2014). Secondly, better tree performance and reduced mortality rate following thinning were associated with changes in predawn shoot water potential (Stoneman et al 1997;Stone et al 1999). According to previous work looking at hydraulic adjustments of Pinus halepensis, the variation in shoot water potential observed in our work among thinning treatments, i.e., -1.7, -1.85, and -2.0 MPa in the intense, moderate, and control treatment, respectively, corresponds to twofold variation in stomatal conductance (g s ), i.e., *0.2, 0.15, and 0.1 mol m -2 s -1 , respectively (Klein et al 2011(Klein et al , 2013.…”
Section: Water Limitationmentioning
confidence: 99%
“…As thinning operations are costly and the financial return expected from these forests is very limited, the idea was to test one-time high-intensity thinning treatments with the aim of achieving a long-term facilitating effect on residual trees while allowing more growing space for natural regeneration and gradual development of a more complex and resilient forest ecosystem (Osem et al 2009. Forest thinning was previously shown as an effective silvicultural tool for promoting tree performance in general (González-Ochoa et al 2004;Ruano et al 2013;Olivar et al 2013) and alleviating drought stress in particular (Stoneman et al 1997;Zausen et al 2005;Rais et al 2014;Gebhardt et al 2014). However, the usefulness of applying high-intensity thinning in mature excessively dense stands has been very little studied (del Campo et al 2014).…”
Pinus halepensis plantations are widespread throughout semiarid-subhumid landscapes of the Mediterranean. Recently, drought-induced decline has often been reported raising concerns with regard to the future of these man-made ecosystems. The study was set out to investigate thinning as a means to alleviate water stress and improve performance of mature P. halepensis plantations experiencing prolonged drought. The study was conducted in a 40-year-old P. halepensis forest in the Jerusalem Mountains of Israel (rainfall: 550 mm year -1 ). Declining stands (stand basal area increment, BAI stand & -3 % year -1 ) were treated by thinning: (1) intense thinning-tree density, BA stand , and leaf area index (LAI) reduced by 81, 68, and 59 %, respectively; (2) moderate-56, 48, and 26 %, respectively;(3) control (*560 tree ha -1 ). Plots of 70 9 70 m were used in four replicates. Individual tree-to stand-level variables were monitored during 4 years through stem and leaf area metrics alongside with predawn shoot water potential (w PD ) and tree mortality. Thinning ameliorated drought stress, reduced mortality, and improved individual tree growth (w PD = -1.7, -1.8, and -2.0 MPa; mortality = 0.2, 2, and 5 % year -1 ; BAI tree = 3.4, 2.0, and 1.4 % year -1 in intense, moderate, and control treatments, respectively). Thinning effects became more pronounced with time. LAI and individual tree leaf area (LA tree ) fluctuated with association to annual rainfall. Higher LA tree caused by thinning reflected a ''selection effect'' while increased leaf area efficiency (BAI per unit LA tree ) was attributed to a ''release effect'' of thinning.
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