Mahayani, Ni Putu DianaSlik, Ferry J. W.Webb, Edward L.Savini, Tommaso...
12页
查看更多>>摘要：Examining ecosystem functioning of logged-over forests requires a quantitative trait-based monitoring approach, in addition to a taxonomic approach, which allows for evaluation of the accompanying shifts in species traits and functional composition. Our study evaluated forest regrowth after different logging and thinning techniques applied to 60 one-hectare forest subplots in East Kalimantan that were logged using selective conventional and reduced-impact techniques. We used seven functional traits to compare the short-term (similar to 1-year) and longer-term (similar to 10-year) changes in functional diversity and composition of the forest. Both conventional and reduced impact logging resulted in higher functional diversity after 10 years, but forest functional traits shifted away from those observed in unlogged (control) subplots. Reduced-impact logging led to smaller deviations in functional composition compared to unlogged forest. We found that low-intensity reduced-impact logging, i.e., <3 m(2) ha 1 (equivalent to 5 trees ha 1 or approximately 42 m(3) ha(-1)), maintained functional diversity equivalent to unlogged forest measured in 12 one-hectare control plots. Selectively logged forest subplots with liberation thinnings increased functional diversity while leaving the trait composition unchanged. Thinned subplots exhibited higher functional diversity than the un-thinned subplots and greater similarity to unlogged forest. However, high-intensity thinning, i.e., >10 m(2) ha(-1), resulted in large functional traits shifts away from unlogged forest. Our study suggests that preserving the original forest functionality, i.e., by applying low intensity, reduced-impact logging and thinning operations, represents a sustainable strategy for long-term tropical forest management.
Masullo, Liamara SantosFerraz, Alexandre de VicenteTertulino Rocha, Jose HenriqueValdo, Gabriel de Castilho...
11页
查看更多>>摘要：Eucalyptus is one of the most commonly planted genera worldwide for commercial timber purposes. Brazil has approximately 25% of the total Eucalyptus spp. planted worldwide. However, nutritional disorders caused by copper (Cu) and zinc (Zn) deficiencies have been more frequent in Eucalyptus plantations. Furthermore, the scientific knowledge regarding micronutrient fertilization is scarce. Sequential extraction can determine the distribution of metals in the soil, giving an order of magnitude to its bioavailability. The present study aimed to assess the soil Cu and Zn pools and evaluate the effects of mineral Cu and Zn fertilization on the nutritional status and nutrient fractionation in a Ferralsol in a cultivated Eucalyptus grandis plantation. The study considered two conditions-namely, forest residue management or removal of forest residues. The treatments included complete fertilization, no application of Cu, no application of Zn, maintenance of forest residues, and total removal of forest residues. High quantities of Cu and Zn were found in the soil, mainly in the low plant-available forms (>60%). There were no differences in the nutritional status of the trees, despite the absence of Cu and Zn via fertilizers and the removal of harvest residues. Foliar Cu concentration was positively correlated with soil exchangeable and oxide-bound Cu content, whereas foliar Zn concentration was positively correlated with soil exchangeable and organic matter-bound Zn content. The access to moderately labile forms of Cu and Zn by eucalypts may justify the absence of response to mineral fertilization, especially in areas where forest residues remain on the soil, and consequently, work as a source of Cu and Zn.
Fischer, SarahWalsh, Christopher J.Sammonds, Michael J.Catford, Jane A....
8页
查看更多>>摘要：Riparian forest loss and degradation due to river-floodplain disconnection is a global problem. Prospects for the maintenance and recruitment of riparian trees via restored flooding can be uncertain, in part due to competition from understorey vegetation and limited availability of tree propagules. In a field-based trial, we assessed the response of a keystone riparian tree to restored flooding, reduced competition and seed addition. We built diversion weirs to reconnect floodplains supporting riparian forest. Using a multiple controlintervention-reference study design with two restored flooding (intervention) sites, two naturally-engaged (reference) and two dry (control) sites, we assessed seedling recruitment of the dominant tree, Eucalyptus camphora, with and without clearance of understorey vegetation and with and without seed addition. We also assessed the growth of extant trees using dendrometers and seedfall using funnel traps at all six sites. Our weirs resulted in extensive flooding of the adjacent floodplain, while control sites remained dry. Flooding increased seed germination, seedling establishment, tree growth and seedfall. However, seed germination benefits were only realised where understorey vegetation was cleared and seed was added. Seedling establishment was also limited by dry summer conditions, except where flooding duration was longest (similar to 6 months cf. < 3 months). Restored flooding via river-floodplain reconnection is likely to promote the rehabilitation of riparian forests degraded by flow regulation or stream modification through benefits at multiple tree life-history stages. However, widespread tree recruitment may require complementary works that reduce competition via clearing of understorey vegetation and alleviate seed limitation by direct seeding or planting.
查看更多>>摘要：Over the past fifty years, societies have placed increasing demands on forests, and their use has shifted gradually from wood production to the diversified benefits and functions of ecosystem services. The effects of neighborhood-based structural characteristics on regulating growth and promoting sustainability have therefore drawn much attention. However, direction for managing natural mixed forests using neighborhood-based indexes are still not clear. Thus, a tree-level harvest planning tool that considers four neighborhood-based structural indexes (species mingling, diametric differentiation, horizontal spatial pattern and crowdedness of trees) while concurrently recognizing other operational constraints, was developed using simulated annealing algorithm. The approach was applied to four 1-ha mapped stands in northeast China, namely a natural larch forest (NLF), a natural birch forest (NBF), a natural secondary forest (SEF), and a Korean pine broad-leaved forest (KBF). The results indicated that the tree-level harvest optimization tool improved the objective function values by approximately 78.33% of NLF, and 134.96% of NBF, and 156.70% of SEF and 252.95%, respectively. The optimal harvest intensities for partial cutting activities varied from 22.16% (SEF) to 26.07% (NBF) of the standing volume. In evaluating the four neighborhood-based structural indexes, both species mingling and crowdedness have the highest priority to be adjusted in structure-based forest management. Our results demonstrated that that the commonly used neighborhood-based structural indexes could be employed to control the spatial layout of potential harvest trees, in turn may be conducive to regulate the growth and stability of forests.
DeCesare, Nicholas J.Peterson, Collin J.Bishop, Chad J.Mitchell, Michael S....
11页
查看更多>>摘要：Land and wildlife managers use disturbance to reset forests to earlier successional stages and improve the quality and quantity of forage available to ungulates. However, management of vegetation communities to increase forage nutrition has additional implications for other non-forage vegetation. To evaluate responses of vegetation to management of fire and timber harvest, we measured and modeled 3 metrics of vegetative response in 3 forested areas in Montana, USA during 2017-2019: forage nutrition for mule deer (Odocoileus hemionus), invasive species biomass, and floristic quality, a measure of plant communities' tolerance of disturbances and fidelity to particular environments using native species conservatism scores. We found differences in all 3 metrics of plant responses that were specific to disturbance type and study area, and associations between disturbance and vegetation outcomes that were both desirable and undesirable. Generally, deer forage nutrition and invasive species biomass both increased in disturbed areas, whereas floristic quality increased with disturbance in 2 study areas but decreased in the third. Biomass of particular invasive species varied according to both study area and disturbance type. Lastly, we used decision analysis to illustrate trade-offs and overall support for different management actions while also accounting for underlying differences among study areas. For example, management actions with the greatest increase in mule deer forage nutrition tended to also increase invasive species biomass. Compared to other management actions, low-severity harvest scored highly in 2 study areas due to its association with increased forage nutrition while also limiting invasive species biomass and maintaining floristic quality. However, different weighting schemes according to different management priorities among management outcomes alter the relative ranking of actions. Our data show area-specific trade-offs in vegetation outcomes that result from disturbance management, which can be combined with decision analysis to help managers balance objectives and compare potential management actions.
查看更多>>摘要：The ongoing global warming and associated drying are shaping the fate of forests worldwide. While processes of tree mortality are visible and studied, a decrease in forest regeneration is mostly overlooked, although equally deleterious. Populations at the edge of tree species distribution areas are at higher risk and are hence hotspots for species extinctions. Here we use a semi-arid pine forest growing at the timberline edge of forest existence as a model for forest survival under warming and drying conditions. Seedling recruitment, including seed germination, seedling survivorship, and multiyear seedling growth, were measured along six consecutive years. To pinpoint the role of drought, we designed a field experiment, manipulating stand density at three levels and grazing regimes. Seed germination was high across all studied plots, but seedling survivorship and multiyear seedling growth were near-zero. Stand density and grazing exclusion positively affected germination. Seedling survivorship was higher in wetter years. Multiyear seedling growth was stunted by grazing, and seedling height was distributed differently across different stand densities. Our data indicate that seedling survivorship during the first dry season acts as a bottleneck for forest existence at the dry and hot edge of current forest distribution. We also quantified the roles of other stressors such as shading, and highlighted the eliminating role of grazing on multiyear seedling growth. Forest regeneration should be more closely monitored in sensitive populations, as climate change-driven forest loss can happen even without mature tree mortality.
NSTL
Elsevier