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1.
The management of burnt wood after a fire may affect seed predation by vertebrates due to the change produced in habitat structure. We analyze the effect of burnt wood management on post-dispersal seed predation in the Holm oak. Three plots were established in a burnt forest, with three treatments per plot: (1) non-intervention (NI, all trees left standing), (2) “partial cut plus lopping” (PCL, felling 90% of trees, cutting their main branches, leaving all the biomass in situ), and (3) “salvage logging” (SL, felling the logs for their removal and masticating the woody debris). Acorns were buried to mimic dispersal by jays or rodents two and three years after fire, with two trials per year (7200 monitored acorns), and the predation rate was evaluated until the time of seedling emergence. The spatial patterns of acorn predation were assessed by computing a transformed-Ripley's K function and Moran's I correlograms. There was a large spatial and temporal variability in acorn predation, with differences among trials, plots, and replicates within treatments and plots. Overall, PCL showed the lowest predation values (83.0% versus 87.4 in NI and 88.0 in SL). Predator species (mice versus wild boar) also differed among treatments, wild boar having a negligible effect in PCL, presumably due to the physical barrier of felled logs and branches. The results support that: (1) salvage logging offers no advantage against predators and (2) that post-fire burnt wood management alters the guild of acorn predators and may reshape the pattern of seedling establishment.  相似文献   

2.
Post-fire salvage logging is a common silvicultural practice around the world, with the potential to alter the regenerative capacity of an ecosystem and thus its role as a source or a sink of carbon. However, there is no information on the effect of burnt wood management on the net ecosystem carbon balance. Here, we examine for the first time the effect of post-fire burnt wood management on the net ecosystem carbon balance by comparing the carbon exchange of two treatments in a burnt Mediterranean coniferous forest treated by salvage logging (SL, felling and removing the logs and masticating the woody debris) and Non-Intervention (NI, all trees left standing) using eddy covariance measurements. Using different partitioning approaches, we analyze the evolution of photosynthesis and respiration processes together with measurements of vegetation cover and soil respiration and humidity to interpret the differences in the measured fluxes and underlying processes. Results show that SL enhanced CO2 emissions of this burnt pine forest by more than 120 g C m−2 compared to the NI treatment for the period June-December 2009. Although soil respiration was around 30% higher in NI during growing season, this was more than offset by photosynthesis, as corroborated by increases in vegetation cover and evapotranspiration. Since SL is counterproductive to climate-change and Kyoto protocol objectives of optimal C sequestration by terrestrial ecosystems, less aggressive burnt wood management policies should be considered.  相似文献   

3.
ABSTRACT

Wood supply is one of the most significant cost items for most forest industries, and costs of forest operations and sale prices of wood is vital information for forest owners. Cost trends between 2000 and 2017 in Swedish forestry is analysed, separately for final felling and thinning, and subdivided into ordinary and salvage operations. Data on costs for operations totalling 821 million m3 harvested roundwood were analysed, both as actual costs and after adjustment for the consumer price index. Adjusted costs for ordinary harvesting operations declined between 2000 and 2007, increased during 2008 and 2009 and have since been relatively constant. Costs of salvage logging operations performed as thinning were 21% higher than ordinary thinning, and when performed as final felling costs were 64% higher than in ordinary final felling. The relative logging cost trends in Sweden and Finland were similar during the period, and there are similarities with the US. However, while logging costs in Sweden and Finland increased in 2008 and 2009, they declined in the US and did not reach the same relative level as in Sweden until 2013. Results can be used for benchmarking logging costs between regions or larger buyers of logging services.  相似文献   

4.
Burnt wood remaining after a wildfire is a biological legacy with important implications for habitat structure, ecosystem regeneration, and post-fire management. Knowledge of the time required for snags to fall is thus a key aspect for planning forest restoration. In this study, we analyze the fall rate of burnt trees in a Mediterranean pine reforestation. Three plots of 18–32 ha were established after a fire across an elevational gradient spanning from 1400 to 2100 m a.s.l., and snag fall rate was measured on a yearly basis using an experimental setup that considered two levels of a thinning treatment: unthinned (where no post-fire management was conducted and all the snags were left standing after the fire) and thinned (where 90% of the trees were cut after the fire and left on the ground). All the snags remained standing during the first and second winter, and thereafter, they collapsed quickly until reaching 100% after 5.5 years. Snags in low-density stands resulting from thinning fell faster than in unthinned stands, but the differences were minor. There was a negative effect of tree diameter on the rate of collapse, especially in the unthinned treatment, but the effect of diameter was minor too. There was no effect of the elevational gradient on fall rate despite patent differences in climatic conditions and pine species across plots. The results support the contention that post-fire fall rate in dense pine plantations in Mediterranean mountains can occur quickly after the second winter and may show little variation across environmental gradients.  相似文献   

5.
After a wildfire, the management of burnt wood may determine microclimatic conditions and microbiological activity with the potential to affect soil respiration. To experimentally analyze the effect on soil respiration, we manipulated a recently burned pine forest in a Mediterranean mountain (Sierra Nevada National and Natural Park, SE Spain). Three representative treatments of post-fire burnt wood management were established at two elevations: (1) “salvage logging” (SL), where all trees were cut, trunks removed, and branches chipped; (2) “non-intervention” (NI), leaving all burnt trees standing; and (3) “cut plus lopping” (CL), a treatment where burnt trees were felled, with the main branches lopped off, but left in situ partially covering the ground surface. Seasonal measurements were carried out over the course of two years. In addition, we performed continuous diurnal campaigns and an irrigation experiment to ascertain the roles of soil temperature and moisture in determining CO2 fluxes across treatments. Soil CO2 fluxes were highest in CL (average of 3.34 ± 0.19 μmol m−2 s−1) and the lowest in SL (2.21 ± 0.11 μmol m−2 s−1). Across seasons, basal values were registered during summer (average of 1.46 ± 0.04 μmol m−2 s−1), but increased during the humid seasons (up to 10.07 ± 1.08 μmol m−2 s−1 in spring in CL). Seasonal and treatment patterns were consistent at the two elevations (1477 and 2317 m a.s.l.), although respiration was half as high at the higher altitude.Respiration was mainly controlled by soil moisture. Watering during the summer drought boosted CO2 effluxes (up to 37 ± 6 μmol m−2 s−1 just after water addition), which then decreased to basal values as the soil dried. About 64% of CO2 emissions during the first 24 h could be attributed to the degasification of soil pores, with the rest likely related to biological processes. The patterns of CO2 effluxes under experimental watering were similar to the seasonal tendencies, with the highest pulse in CL. Temperature, however, had a weak effect on soil respiration, with Q10 values of ca. 1 across seasons and soil moisture conditions. These results represent a first step towards illustrating the effects of post-fire burnt wood management on soil respiration, and eventually carbon sequestration.  相似文献   

6.
Post-fire forest regeneration is crucial to forest management. Three different restoration treatments including natural regeneration (NR), artificial regeneration (AR), and artificial promotion (AP), were adopted in the Greater Hinggan Mountain area of China after a serious fire occurred on May 6, 1987. NR is a control treatment where recovery occurs naturally without intervention, AR comprises salvage logging followed by planting, while AP includes regeneration by removing dead trees, weeding, and tidying to promote seed germination. In this study, the objective was to detect and compare the effects of the three restoration treatments using radar indices derived from ALOS/PALSAR data. Four time-series SAR images were pre-processed to acquire the backscattering coefficients. Then the coefficients in both HH and HV polarization were examined and two radar vegetation indices were derived and evaluated, based on which, the post-fire forest dynamics under different restoration treatments were detected and compared. The results showed that the forests under NR presented a completely different recovery trajectory compared to those under the other two treatments. This difference could be characterized by both the backscattering intensity in HH and HV polarization and two radar indices. This study indicated the effects of different restoration treatments, as well as demonstrated the applicability and efficiency of radar remote sensing techniques in forest monitoring and management.  相似文献   

7.
基于永新县七溪岭林场采伐迹地森林恢复的森林调查,从树高生长量和蓄积生长量两个方面分析选择不同树种造林的林地生产能力,总结同一树种连栽的生产能力低下和更换树种造林的效果显著,指出采伐迹地森林恢复树种选择对国有林场大面积经营森林的重要性以及树种选择的方法。  相似文献   

8.
In East Kalimantan (Indonesia), impacts of conventional (CNV) and reduced-impact logging (RIL) on forest ecosystems were compared on the basis of pre- and post-harvesting stand inventories. There was a positive and significant correlation between the proportion of trees damaged by felling and the density of trees felled. Logging intensity ranged from 1 to 17 trees ha−1(9–247 m3 ha−1) and averaged 9 trees ha−1 (86.9 m3 ha−1). The study has shown that with RIL techniques, logging damage on the original stand can be significantly reduced by 50% compared with conventional logging. However, this 50% reduction in logging damage, was dependent on the felling intensity. With a felling intensity of 8 stems ha−1 or less, RIL techniques only damaged 25% of the original tree population whereas 48% were damaged with conventional techniques. Above this felling intensity (i.e. 8 stems ha−1), the effectiveness of RIL in limiting forest damage was significantly reduced, mainly because of the increasing felling damage. Moreover, the removal of all harvestable timber trees, leaving only few potential crop trees, will result in a seriously depleted residual stand. Because of the high damage involved by high felling intensity, leaving few potential crop trees, and the yield capacity of the remaining stand, acceptable harvesting volume will not be reached within the felling rotation of 35 years. It is concluded that silvicultural system based on diameter limit alone, as is the Indonesian system (TPTI), cannot be compatible with sustainability and more sophisticated harvested-selection rules are needed.  相似文献   

9.
Decline of cavity-using wildlife species is a major forest management issue. One of the causes of this problem is the loss in cavity tree abundance, resulting from short rotation silviculture, stand-replacing disturbance events and timber harvesting in disturbed stands. Cavity tree availability cannot be guaranteed due to the stochastic nature of disturbance events. We developed a Markov model to predict future cavity tree availability under alternative tree felling and fire protection strategies using information on cavity tree dynamics and fire history. Stochastic dynamic programming was used to find a strategy that maximizes timber revenues less forest management costs, including the cost of an artificial nest-box program that must be implemented whenever cavity trees become critically scarce. The requirement to implement a nest-box program in such circumstances strongly influenced the optimal tree felling strategy and resulted in a higher probability of having cavity trees in the future. This reflected an increase in the retention of old growth forest and stands with fire-killed cavity trees as well as stands of younger trees to provide a future source of cavities. These results demonstrate the need to consider the costs of artificial habitat enhancement and the risk of future cavity tree scarcity in multiple-use forest management planning.  相似文献   

10.
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11.
Selective logging is an important socio-economic activity in the Congo Basin but one with associated environmental costs, some of which are avoidable through the use of reduced-impact logging (RIL) practices. With increased global concerns about biodiversity losses and emissions of carbon from forest in the region, more information is needed about the effects of logging on forest structure, composition, and carbon balance. We assessed the consequences of low-intensity RIL on above-ground biomass and tree species richness in a 50 ha area in northwestern Gabon. We assessed logging impacts principally in 10 randomly located 1-ha plots in which all trees ?10 cm dbh were measured, identified to species, marked, and tagged prior to harvesting. After logging, damage to these trees was recorded as being due to felling or skidding (i.e., log yarding) and skid trails were mapped in the entire 50-ha study area. Allometric equations based on tree diameter and wood density were used to transform tree diameter into biomass.Logging was light with only 0.82 trees (8.11 m3) per hectare extracted. For each tree felled, an average of 11 trees ?10 cm dbh suffered crown, bole, or root damage. Skid trails covered 2.8% of the soil surface and skidding logs to the roadside caused damage to an average of 15.6 trees ?10 cm dbh per hectare. No effect of logging was observed on tree species richness and pre-logging above-ground forest biomass (420.4 Mg ha−1) declined by only 8.1% (34.2 Mg ha−1). We conclude from these data that with harvest planning, worker training in RIL techniques, and low logging intensities, substantial carbon stocks and tree species richness were retained in this selectively logged forest in Gabon.  相似文献   

12.
Pre-marked skid trails, directional felling and climber cutting when logging in tropical rainforests may be important ways of reducing damage to the forest, thus creating a healthier stand and improving future yields.This study, carried out in a virgin dipterocarp rainforest in the south of Sabah, Malaysia, compared two types of logging (both with and without pre-cutting climbers): conventional selective logging (CL) and supervised logging (SL). The latter is a selective logging system in which both pre-marked skid trails and directional felling were implemented. The pre-marked skid trails were aligned parallel to each other, spaced 62 m apart. A randomised complete block 2 × 2 factorial design was used in the experiment, consisting of 16 gross treatment plots, each of 5.76 ha with a 1 ha net plot in the centre.Fewer trees tended (0.050 < P ≤ 0.100) to be logged in SL plots than in CL plots (on average 9.4 and 13.0 trees ≥60 cm diameter breast height ha−1). Pre-felling of climbers resulted in four more dipterocarp trees being logged ha−1, compared with no climber cutting: a statistically significant difference (P ≤ 0.050). The basal areas lost of both large trees (≥ 60 cm dbh) and small dipterocarp trees (10–29 cm dbh) tended to differ between the logging systems, with CL leading to greater losses.There were significant differences in the residual stands left by the logging systems, with respect to the number of dipterocarps and their basal area in the diameter class 10–29 cm; ca 30% more stems being found after SL. No significant differences (or tendencies) in these variables were found in the residual stands in other diameter classes, or when trees of all species were considered.  相似文献   

13.
This article focuses on timber sourced from the agricultural areas in the shifting cultivation landscapes of the Central Region of Cameroon. Data about volumes marketed in urban centres, harvesting operations and on-farm timber management are used to discuss the ecological impact of small-scale logging and its sustainability in the long term. An opportunistic association exists between small-scale logging and agricultural land uses, determined mostly by the abundance of valuable species in fallows and on cocoa farms, their easy accessibility and the low price of farmland timber. Farmers apply various strategies to the management of tree resources in fallows and cocoa agroforests, with most felling authorized in fallows and most trees preserved on the cocoa farms. With current agricultural expansion and intensification trends associated with small-scale logging, timber resources on rural land are at risk of depletion with direct consequences for domestic timber supply and the thousands of livelihoods it sustains. Marketing and regulatory changes are needed to encourage the integration of timber production in agricultural management systems.  相似文献   

14.
关于天然林采伐工程与迹地生态系统恢复的探讨   总被引：3，自引：0，他引：3  
天然林采伐工程从策划到作业都应考虑迹地生态系统保护和恢复,要用系统工程的方法,控制好每个环节。主伐区划要充分考虑迹地更新造林的特性要求和抚育的特性要求;采伐方式的确定应着眼于生态系统的整体性和稳定性的保护;天然林木材采伐工程作业过程,无论是采伐木的确定、树倒方向的控制还是集材作业每个单元过程,都应树立迹地生态系统保护和恢复的思想。  相似文献   

15.
We developed a model to estimate supply potentials and available amounts of timber and forest biomass resources from profitable sub-compartments of thinning and final felling operations. Economic balances were estimated while considering not only harvesting expenses but also reforestation expenses after final felling, which should be considered for sustainable forest management. Harvesting expenses were estimated based on two types of timber harvesting systems and three types of forest biomass harvesting systems in each sub-compartment. Then, the model was applied to Nasushiobara city of Tochigi prefecture, Japan. Reforestation expenses had large negative impacts on the financial balances of final felling operations. Few sub-compartments were profitable after considering reforestation expenses. Most profitable sub-compartments were those with mechanized operation systems and landing sales. These accounted for 17.19% of all sub-compartments, while only 5.75% of the sub-compartments were profitable based on their current operation systems and landing sales. Although the overall supply potentials of timber and forest biomass resources were 380,000 m3 and 210,000 Mg, respectively, and 15 times the planned harvest of coniferous tree volume of 25,000 m3year-1 and 50 times the annual demand for the woody gasification power generation of 4,000 Mg year-1 in Nasushiobara, available amounts of timber and forest biomass resources were only49,429 m3 and 33,333 Mg, which were 13.0% and 15.7% of supply potentials for landing sales with mechanized operation systems.  相似文献   

16.
The authors tested two harvesting systems especially designed for mallee agroforestry plantations on farmland. Both systems were based on versatile forest technology commonly used for conventional logging operations. They differed especially for the felling technology: small-scale drive-to-tree or industrial swing-to-tree equipment. Both systems were tested side-to-side on 12 experimental plots each. The resulting harvesting cost was 22 and 27 AU$ t?1, for the industrial and the small scale system, respectively. Chipping represented between 60 and 80 % of the overall harvesting cost, and offered much room for improvement. The industrial system always offered the lowest harvesting cost, regardless of annual usage, when equipment mobilisation costs were not considered. The productivity of conventional forestry equipment was strongly dependent on belt stocking and tree size. If the diameter at ankle height dropped below 10 cm, economic viability decreased very rapidly.  相似文献   

17.
To determine the effect of burnt tree removal on post-fire natural regeneration of Pinus halepensis, two 2 500 m2 areas were selected six months after the fire in a totally destroyed mature (>70 years) pine forest. In one area, all the trees were cut down and removed 10 months after the fire and, in the other, all the trees were left standing (control). In each area, 20 permanent plots of 20 m2 each were randomly placed, and all seedlings emerging within them labeled by individual numbered plastic tags. Emergence, mortality, density and growth (height) of 6649 P. halepensis seedlings were monitored during the first four post-fire years. Seedling emergence was concentrated in the first post-fire autumn–winter period. No positive effect on seedling emergence was detected as a consequence of burnt trunk dragging and subsequent turning over of soil. Wood removal produced an immediate average seedling mortality of 33%, and notably increased seedling mortality during the subsequent summer, probably due to increased exposure of seedlings to sunlight and the possible debilitation of many individuals by mechanical contact during burnt wood removal. A negative correlation of pine seedling mortality with height was detected, which increased significantly on wood removal in the third post-fire year. That is, short seedlings (<10 cm) in treated plots were the most likely to die during this period. In spite of the detrimental effect of wood removal on sapling survival, seedling density four years after fire in the cleared area was large (3.3 seedlings/m2). Wood removal treatment reduced seedling growth: seedling height was significantly higher in the control stand, and differences in seedling height growth rate became particularly noticeable in the fourth post-fire year. The results denote that traditional wood removal practices do not threaten natural post-fire P. halepensis re-establishment if initial seedling density is large enough. However, further studies focused on wood removal effects on the final tree development level and other ecological aspects are necessary to choose adequate post-fire forest management.  相似文献   

18.
Recurrence of recent large wildfires is threatening the permanence of Pinus nigra Arnold (Black pine) forests in central Catalonia (NE Spain), due to the almost nil post-fire regeneration of this non-serotinous pine. Potential practices to carry out extensive reforestation programs with P. nigra may differ widely in terms of their final success, economic cost and undesired ecological impact. In this framework, we have analysed different types of vegetation clearing (mechanical, controlled burning or grazing), soil preparation (ripping or planting holes) and reforestation methods (broadcast seeding, spot seeding and planting) to restore P. nigra forests. We have compared these practices in terms of seedling establishment, but also in the light of their economic costs and ecological impact, through a new multi-criteria analysis. Seedling establishment after sowing was very poor and not influenced by vegetation clearing. In plantations, seedling survival was higher in the ripper treatment than in planting holes for all vegetation clearing treatments except the control one. Nevertheless, the higher economic cost of the planting holes treatment and the negative impact of mechanical clearing and burning on the small mammals community made the stated differences in seedling survival irrelevant. Thus, the multi-criteria analysis revealed that the two most preferred options were planting in uncleared or lightly grazed areas with soil preparation through ripping. This study gives some valuable insights about the use of new decision-support tools in restoration programs and provides practical guidelines concerning the restoration of extensive burned P. nigra forests.  相似文献   

19.
This study examines the optimal method to extract logging residues from small, fragmented and scattered forests separately from the mechanized operational systems used on aggregated forestry operation sites. First, small-scale logging systems operated by a private logging contractor and an individual forest owner were investigated. Regression equations for estimating felling and processing cycle times were established as a function of stem and log volumes, respectively. Equations to estimate the forwarding and transporting cycle times were established as a function of the forwarding and transporting distances using the forwarding and transporting velocities, respectively. Then, equations to estimate productivities and costs were established with the cycle times, volumes and hourly operational expenses consisting of labour and machinery expenses. Finally, costs of the small-scale systems—mini-forwarder and 4 t truck operated by a private logging contractor, and manual logging and light truck operated by an individual forest owner—were estimated and compared with the mechanized operation system operated by the Forest Owners’ Association. The mechanized operation system was found to have the highest cost and could not compete for small forestry operational sites and small stem volumes. The small-scale systems could be effective for harvesting small areas. This was especially true when conducting extracting operations without machines, as done by the individual forest owner, and transporting operations by a private logging contractor, in which the hourly income of the individual forest owner was higher than the hourly labour expenses.  相似文献   

20.
The role of disturbance in structuring vegetation is widely recognized; however, we are only beginning to understand the effects of multiple interacting disturbances on ecosystem recovery and development. Of particular interest is the impact of post-disturbance management interventions, particularly in light of the global controversy surrounding the effects of salvage logging on forest ecosystem recovery. Studies of salvage logging impacts have focused on the effects of post-disturbance salvage logging within the context of a single natural disturbance event. There have been no formal evaluations of how these effects may differ when followed in short sequence by a second, high severity natural disturbance. To evaluate the impact of this management practice within the context of multiple disturbances, we examined the structural and woody plant community responses of sub-boreal Pinus banksiana systems to a rapid sequence of disturbances. Specifically, we compared responses to Blowdown (B), Fire (F), Blowdown-Fire, and Blowdown-Salvage-Fire (BSF) and compared these to undisturbed control (C) stands. Comparisons between BF and BSF indicated that the primary effect of salvage logging was a decrease in the abundance of structural legacies, such as downed woody debris and snags. Both of these compound disturbance sequences (BF and BSF), resulted in similar woody plant communities, largely dominated by Populus tremuloides; however, there was greater homogeneity in community composition in salvage logged areas. Areas experiencing solely fire (F stands) were dominated by P. banksiana regeneration, and blowdown areas (B stands) were largely characterized by regeneration from shade tolerant conifer species. Our results suggest that salvage logging impacts on woody plant communities are diminished when followed by a second high severity disturbance; however, impacts on structural legacies persist. Provisions for the retention of snags, downed logs, and surviving trees as part of salvage logging operations will minimize these structural impacts and may allow for greater ecosystem recovery following these disturbance combinations.  相似文献   

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