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1.
We usually have only limited knowledge about the economic consequences of land-use decisions, thus they are uncertain. We analyze the implications of this uncertainty on conservation payments (CP) to preserve wildlife-friendly shade coffee production in southwest Ecuador, when conversion to maize is the most profitable alternative. Our objective is twofold: First, we analyze the consequences of applying Stochastic Dominance (SD) to derive CP, an approach making only minimal assumptions about the preferences of farmers. Second, we investigate the effects of land-use diversification to reduce CP by allowing for shade coffee on part of a landholding, and maize production on what remains. CP derived by SD turned out to be at least twice the amount calculated by an alternative method which maximizes a concave utility function—US$ 166 to US$ 294 ha?1 year?1 instead of US$ 86 ha?1 year?1. Given this result, we doubt that the assumptions underlying SD are reasonable for farmers, who are known to be risk-averse. Allowing for land-use diversification has a significant impact on CP. The optimal portfolio share of shade coffee is 27 % and for maize 73 % for moderately risk-averse farmers—without any CP. A larger share of shade coffee is preferable for strongly risk-averse farmers—51 and 49 % maize. The amount of CP necessary to encourage the expansion of shade coffee to 75 % is US$ 40 ha?1 year?1 (for moderately risk-averse) and US$ 19 ha?1 year?1 (for strongly risk-averse farmers). Stimulating diversification may thus help to significantly reduce CP necessary to preserve less profitable agroforestry options.  相似文献   

2.
We evaluated two biomass harvest methods, (1) Whole Tree Thinning (WTT; third-row thinning), and (2) Whole Tree Thinning with Fuelchips (WTTF; third-row thinning plus remove all accessible hardwood stems >2.5 cm diameter at breast height and understory shrubs in thinned area of stand) in a 21-year-old loblolly pine (Pinus taeda L.) plantation in northwest Florida for their harvesting yields and productivities, costs, and effects on groundcover. Both WTT and WTTF produced similar quantities of roundwood (~70 Mg ha?1) and chips (8.43–13.12 Mg ha?1) without significantly added operational time (15.77–28.12 Mg h?1). On-board costs of chip production (US$6.93 to 10.60 Mg?1) and total cost of roundwood and chip production (~22.5 US$ Mg?1) of the two harvest methods also did not differ significantly. Following either WTT or WTTF, overall percent groundcover recovered within 6 months. While shrub and grass cover were similar, forb cover in WTT increased significantly following six months of harvests. Importantly, the study suggests that biomass removal is an attractive option that could be integrated with traditional silvicultural thinning methods to manage vegetation and alleviate hazardous fuel and wildfire conditions, leading to improved forest health.  相似文献   

3.
Recent re-measurements of silvicultural trials in conifer plantations on nutrient-poor cedar-hemlock (CH) cutovers on northern Vancouver Island have confirmed co-limitation by nitrogen and phosphorus. Repeated fertilization increased volumes of both cedar and hemlock on CH sites (at 2,500 stems ha?1) by about 100 m3 ha?1 relative to unfertilized plots 22 years following initial fertilization, and increased the productivity of regenerating conifers to a level approximating that of neighbouring hemlock-amabilis fir (HA) sites. More surprising was the response to fertilization on the more-productive HA sites. After 22 years, cedar in fertilized HA plots had produced an extra 180 m3 ha?1 compared to unfertilized HA plots, while hemlock had produced an extra 250 m3 ha?1 in fertilized plots (at 2,500 stems ha?1). Thus, contrary to expectations, the greatest volume responses of both hemlock and cedar to fertilization occurred on the good (HA) sites rather than on the poor (CH) sites. Ecological studies of CH and HA sites supported the hypothesis that the poor nutrient supply and productivity of CH sites is a long-term consequence of excessive moisture, and that the two site types bracket a critical ecological threshold of moisture, aeration and redox.  相似文献   

4.
This study assessed the amount of carbon stored and the economic viability of the small-scale Clean Development Mechanism (CDM) carbon offsets in Pinus caribaea and Eucalyptus grandis plantations under varying rotations. Volume equations were used to estimate carbon stocks and merchantable wood volume in the plantations, while net present value (NPV) and annual equivalent value (AEV) were used as measures of profitability at the optimum economic rotation age as well as at the CDM-defined crediting period of 20 years. The findings show that over a 20-year rotation, E. grandis and P. caribaea plantations sequestered 638 and 418 t CO2-e ha?1, respectively. The NPVs of E. grandis and P. caribaea with carbon credits over the CDM carbon-crediting period of 20 years were US$2 540 ha?1 and US$1 814 ha?1, respectively. This is higher than the NPVs without carbon credits of US$1 543 ha?1 and US$1 390 ha?1 for E. grandis and P. caribaea, respectively. The AEV of E. grandis harvested at its optimal economic rotation of 10 years was US$316 ha?1. This is slightly higher than the AEV of US$298 ha?1, utilising the CDM carbon-crediting period of 20 years. In contrast, the AEV of P. caribaea under the 20-year CDM carbon-crediting period was higher than harvesting at the optimal economic rotation of 16 years without carbon credits. When the average CDM contract establishment costs exceed US$500 ha?1 and US$1 000 ha?1 for P. caribaea and E. grandis woodlots, respectively, it is not economically viable for one to participate in the CDM forest carbon offsets programme. In conclusion, the study results indicate that whereas E. grandis has a higher biological potential to sequester carbon than P. caribaea, it is currently not economically viable for participation in the CDM forest carbon offset scheme. In contrast, it is economically viable for P. caribaea plantations to participate in the CDM, if the CDM contract establishment costs are low.  相似文献   

5.
The Y Ikatu Xingu Campaign brought together indigenous people, farmers, researchers, governmental, and non-governmental organizations seeking riparian forest restoration in the Xingu watershed, in west-central Brazil. Forest restoration is challenging in the region because of scarce nurseries, long distances, and high costs associated with the usual technique of planting nursery-raised seedlings. This article describes mechanized direct seeding and compares it with the planting of seedlings, in terms of cost and tree densities at ages of 0.5 until 5.5 yr after planting. Direct-seeding was mechanized using common agricultural machines designed for sowing cereals or grasses, which were loaded with 200,000 seeds of native trees and 150,000 seeds of annual and sub-perennial legumes, plus 50–150 kg sand ha?1. The Campaign restored more than 900 ha by direct-seeding and 300 ha by planting seedlings. The great demand for native seeds was met by the Xingu Seed Network, formed by Indians, small landholders, and peasants, which commercialized 98 tons of native seeds and earned US$500,000 since 2006. Direct-seeding costs less per hectare than planting seedlings (US$1,845 ha?1 against US$5,106 ha?1), results in higher tree densities (2,500–32,250 trees ha?1 against 1,500–1,650 trees ha?1), is more practical, and creates layers of dense vegetation that better resembles natural forest succession.  相似文献   

6.
《Southern Forests》2013,75(4):253-258
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7.
Carbon stock estimation was conducted in tree species of Sem Mukhem sacred forest in district Tehri of Garhwal Himalaya, Uttarakhand, India. This forest is dedicated to Nagraj Devta and is dominated by tree species, including Quercus floribunda, Quercus semecarpifolia and Rhododendron arboreum. The highest values of below ground biomass density, total biomass density and total carbon density were (34.81±1.68) Mg·ha?1, (168.26±9.04) Mg·ha?1 and (84.13±4.18) Mg·ha?1 for Pinus wallichiana. Overall values of total biomass density and total carbon density calculated were 1549.704 Mg·ha?1 and 774.77 Mg·ha?1 respectively. Total value of growing stock volume density for all species was 732.56 m3·ha?1 and ranged from (144.97±11.98) m3·ha?1 for Pinus wallichiana to (7.78±1.78) m3·ha?1 for Benthamidia capitata.  相似文献   

8.
This study analyses the trade-off between bioenergy production and soil conservation through thinning operations in Norway spruce (Picea abies L. Karst) plantations in Denmark. Thinning operations were evaluated under different regimes and intensities for a complete rotation period of sixty years and for different site qualities (site-classes I–VI). Applying a dynamic forest growth modeling tool, evolution of forest structure was predicted to observe the potentials for biomass production and inevitable soil degradation. Results showed thinning from below, with a higher utilization (maintenance of a minimum basal area of 25 m2 ha?1) could produce more bioenergy. However, these operations require simultaneous severe forest soil degradation. Therefore, the optimum thinning for bioenergy production under preservation constraints was thinning from above with a lower intensity (maintenance of a minimum basal area of 45 m2 ha?1). The ratio of bioenergy win (kWh) to soil-loss (m3 ha?1) was calculated for this regime varying between 74,894 kWh m?3 in a high quality site (site-class I) and 6,516 kWh m?3 in a low quality site (site-class VI) with an average of 44,282 kWh m?3. However, this could not always preserve the highest amount of growing stock essential for natural dynamics of forest ecosystem with an exception of the low quality sites (site-class VI). Thus, when aiming at bioenergy production through thinning operations, trade-offs with soil conservation and growing stock preservation should be regarded to prevent environmental degradation.  相似文献   

9.
We used the coupled forest and rockfall model PICUS Rock’n’Roll, linking a hybrid forest patch model and a 3D rockfall model, to assess the effects of four management scenarios (BAU: business as usual age class shelterwood approach; PFM1 and PFM2: rockfall protection management scenarios with slit-shaped gaps; NOM: no management scenario without any active silvicultural intervention) on rockfall protection and timber production on a 38 ha slope over 100 years. Compared to PFM1 and PFM2, we found slightly more harvested timber for the BAU scenario (BAU: 6.7 m³ha?1yr?1, PFM: 5.7–5.9 m³ha?1yr?1), but lower contribution margins (BAU: 55 €ha?1yr?1, PFM: 113–115 €ha?1yr?1). Overall, depending on rock size and forest state, 30–70% of the simulated rocks that would otherwise hit the road at the foot of the slope were stopped by the forest. While the PFM scenarios maintained a high rockfall protection level over 100 years (PE between 45–64%) the BAU showed periods of reduced protection (PE between 26–65%). The NOM scenario maintained favorable conditions in the beginning, but declining protection efficiency in the last decades of the century (PE 49–63%). We conclude that rockfall protection management can outperform BAU with regard to both timber production and rockfall protection.  相似文献   

10.
In the Sustainable Forest Management, deadwood is a fundamental substrate for numerous species, and a key factor in carbon and nutrient cycles. The main aim of the paper is to estimate the amount of deadwood in two Calabrian pine forests (Monte Morello in Italy; Xanthi in Greece) characterized by different stand conditions and management practices. The second aim is to compare two different sampling methods to estimate the volume of lying deadwood: the fixed-area sampling (FAS) method and the line intersect sampling (LIS) method. The results show that the Monte Morello peri-urban forest is characterized by a high quantity of deadwood (75.1 m3 ha?1) divided in 80% of lying deadwood, 18% of standing dead trees, and 2% of stumps. The Xanthi peri-urban forest is characterized by a total amount of deadwood of 9.21 m3 ha?1 divided in 34% of lying deadwood, 18% of standing dead trees and 48% of stumps. The mean volume of lying deadwood in Monte Morello estimated using the FAS is 59.91 m3 ha?1, while using the LIS the mean volume is 64.9 m3 ha?1. In the Xanthi, the mean volume of lying deadwood is 3.11 m3 ha?1 using FAS and 5.49 m3 ha?1 using LIS.  相似文献   

11.
Maintaining a permanent forest canopy cover and eventually harvesting wood in a final harvest according to predefined dimensions is often considered as prototype for future management of deciduous forests. An uneven-aged structure is considered by the public to resemble “natural” conditions, and by forest engineers it is considered as being more resilient to disturbances. In the Hainich-Dün region of Thuringia, Germany, beech-dominated selection forests covering about 10,000?ha have been managed for almost 1000 years, initially by irregular use, but as regular selection system since about 200 years. Managing these stands remains difficult, due to the lack of yield tables and a quantification of harvest of uneven-aged stands considering differences in site conditions and handling of over-sized trees. It is the objective of the present study to develop tables of target stand volumes, increments, and harvest for different diameter ranges of uneven-aged stands according to site conditions. The present study is based on repeated grid-based inventories of about 2150 plots, which were partly re-inventoried 3 times over the past 20 years. The recommended target wood volumes vary between 296 and 388 m3 ha?1. Stand growth rates of different yield classes were estimated to range between 6.7 and 7.7 m3 ha?1 yr?1 which is 30% lower than for age class forest. Nevertheless, the economic returns are higher. Thus, selective cutting with single tree selection remains a viable silvicultural system, but it may change over time into small-scale shelter-woods for improving growth of regeneration.  相似文献   

12.
Mean tree height, dominant height, mean diameter, stem number, basal area and timber volume of 116 georeferenced field sample plots were estimated from various canopy height and canopy density metrics derived by means of a small-footprint laser scanner over young and mature forest stands using regression analysis. The sample plots were distributed systematically throughout a 6500 ha study area, and the size of each plot was 232.9 m2. Regressions for coniferous forest explained 60–97% of the variability in ground reference values of the six studied characteristics. A proposed practical two-phase procedure for prediction of corresponding characteristics of entire forest stands was tested. Fifty-seven test plots within the study area with a size of approximately 3740 m2 each were divided into 232.9 m2 regular grid cells. The six examined characteristics were predicted for each grid cell from the corresponding laser data using the estimated regression equations. Average values for each test plot were computed and compared with ground-based estimates measured over the entire plot. The bias and standard deviations of the differences between predicted and ground reference values (in parentheses) of mean height, dominant height, mean diameter, stem number, basal area and volume were ?0.58 to ?0.85 m (0.64–1.01 m), ?0.60 to ?0.99 m (0.67–0.84 m), 0.15–0.74 cm (1.33–2.42 cm), 34–108 ha?1 (97–466 ha?1), 0.43–2.51 m2 ha?1 (1.83–3.94 m2 ha?1) and 5.9–16.1 m3 ha?1 (15.1–35.1 m3 ha?1), respectively.  相似文献   

13.

Context

Recruitment is an important process in forest stand dynamics, especially in uneven-aged stands. Continuous recruitment is a prerequisite for diverse, uneven-aged silvicultural systems, but patterns may vary significantly.

Aims

The main goals of the study were to examine the recruitment of the main tree species in selection and irregular shelterwood stands in silver fir?CEuropean beech?CNorway spruce forests and to determine the main predictors of the recruitment occurrence.

Methods

Data from 5,486 permanent inventory plots were used to study recruitment of saplings into the tree layer (diameter at breast height ??10?cm).

Results

Recruitment rate differed significantly between selection (7.6?trees?ha?1?year?1) and irregular shelterwood (26.1?trees?ha?1?year?1) stands. Shade-tolerant fir and beech recruited with higher probability in selection stands, while light-dependent sycamore recruited with higher probability in irregular stands. In addition, forest types, soil pH, stand basal area, mean diameter, and the basal area of the same tree species with respect to recruitment were found to be important predictors of recruitment occurrence.

Conclusions

The application of different uneven-aged silvicultural systems and their forms makes it possible to considerably influence the future tree species composition of uneven-aged forests.  相似文献   

14.
The introduction of carbon finance as an incentive in forestry farming has a potential of increasing the amount of carbon sequestered. However, this has created a daunting task among investors in forestry to optimise the joint production of wood and carbon sequestration. For instance, investors might find it profitable to give up some timber returns in exchange for carbon credits. This study evaluated expected income from growing Cupressus lusitanica Mill., Pinus patula Schiede ex Schltdl. & Cham., Eucalyptus saligna Sm. and Juniperus procera Hochst. ex Endl. for wood and/or the carbon market in central Kenya. The global average unit price of carbon and stumpage royalty were used to estimate expected returns from sale of carbon credits and wood, respectively. There were significant differences (p < 0.01) in the expected amount of income from sale of carbon and wood among the four species. Specifically, at economic rotation of 30 years with stand density of 532 trees ha?1 P. patula and C. lusitanica yielded US$28 050 and US$23 650, respectively, from sale of carbon compared with US$59 000 and US$51 000, respectively, from sale of wood. This was twice the value investors receive from clear-felling as compared with sales from carbon. Similarly, at economic rotation of 33 years with stand density of 150 trees ha?1, a forest investor in E. saligna would earn US$15 400 from sale of carbon compared with US$33 000 from sale of wood. Overall, the amount expected to be realised from sale of carbon was lower compared with that from sale of wood. This demonstrates that the price dynamics of carbon offsets in the voluntary and the compliance markets need to remain competitive and attractive for the forest owners to give up some timber returns in exchange for carbon income or to modify forest management regulation in order to increase carbon sequestration.  相似文献   

15.
With this study we investigated the effective factors on annual amount of total litterfall and needle litterfall in Pinus brutia forests and estimated them with a regression model based on certain stand parameters. We studied 27 permanent plots representing different stand structure and environmental conditions in South-Western Turkey. Litterfall was collected in three month intervals corresponding to each of four seasons for a three-year period. We found a significant relationship between litterfall and stand properties such as crown closure (%), basal area (m2?ha?1), stand stem volume (m3?ha?1), above-ground biomass (t?ha?1), mean annual volume increment (m3?ha?1?yr?1) and site index (T?=?75). Similar relationships also hold true between litterfall and each of such climatic factors as seasonal mean temperature (°C), relative humidity (%) and temperature/precipitation ratio (dimensionless). The mean annual litterfall considerably varied depending on stand characteristics and certain environmental factors. Both needle litterfall and total litterfall may be predicted for long term by regression models using certain stand parameters. Models developed for litterfall of P. brutia forests in this study may be used for national C inventory in Turkey.  相似文献   

16.

Context

Processing young, small eucalypt logs into veneer is a burgeoning industry across southern China. However, plantations supplying these logs were mostly established for pulpwood; little information is available on variation and selection among commercial eucalypt clones/varieties in regards to suitability for veneer production.

Methods

Tree growth and log form were assessed on 11 eucalypt clones from a 5-year-old trial in southern China. Logs from these were rotary peeled for veneer; recovery percentages plus a range of quality and value traits were assessed on the outturn.

Results

Tree volumes, green veneer recovery ratios (%), veneer quality grades, log value, and value m?3 varied significantly among both clones and log positions up the stem. The clone with the best veneer recovery ratio (50.5 %) provided nearly twice that of the poorest clone (28.4 %). Average veneer value log?1 by clone ranged from RMB 6.7 (US$1) up to RMB 15.1 (US$2) and average value m?3 by clone ranged from 589 RMB?m?3 (US$88) up to 925 RMB?m?3 (US$139). Overall, sweep was the key factor influencing veneer recovery ratio and value. Knots, especially dead knots, holes and splitting were major factors influencing veneer quality grade. Middle and upper logs had significantly higher veneer recoveries, grades, and values m?3 than the lower logs.

Conclusions

Excellent potential exists for selecting among eucalypt clones, and even among log positions within trees, for optimizing veneer production.  相似文献   

17.
Abstract

An integrated simulation tool, formed by integrating the InnoSIM sawing simulation system with the RetroSTEM simulator, was used to convert available wood raw materials from final felling into sawn timber, allowing for calculation of the three-dimensional wood properties of individual stems (stem geometry, heartwood formation, knottiness) as well as the volume, quality and value of sawn timber in a Norway spruce stand with different thinning regimes (unthinned, normal and intensively thinned). Based on the input data of sawing patterns, the simulations indicate that there are relatively small differences (<8%) in the volume yield (m3ha?1) of sawn goods resulting from sawlogs available from final felling with different thinning practices. However, intensive thinning yielded the largest stem diameters and the greatest volumes (m3ha?1) of large-sized centre goods (thickness: 50, 63, 75 mm) of rather poor quality. Normal thinning yielded the largest volume of A-grade side boards and centre goods (m3ha?1), as well as the best total value ([euro]ha?1) of sawn timber. Differences observed in sawn timber quality distribution can contribute to even more significant variation in value yields, if pricing mechanisms of timber products change to favour higher grade timber products.  相似文献   

18.
Forest management practices have led to a reduction in the volume and a change in the composition of coarse woody debris (CWD) in many forest types. This study compared CWD volume and composition in reserves and two types of managed forest in the central boreal zone of Sweden. Ten areas were surveyed, each containing clear-cut, mature managed and old-growth stands, to determine the volume of standing and lying CWD in terms of species composition, decay class and size class. Volumes of CWD on clear-cuts and in mature managed forests were high compared with previous studies. Old-growth forests (72.6 m3 ha?1) contained a greater volume of CWD than mature managed forests (23.3 m3 ha?1) and clear-cuts (13.6 m3 ha?1). Differences were greatest for the larger size classes and intermediate decay stages. Despite stand ages being up to 144 years, CWD volume and composition in managed forests was more similar to clear-cuts than to old-growth forests.  相似文献   

19.
《Southern Forests》2013,75(4):311-318
Average wood density of 38-year-old Cariniana legalis (Mart.) Kuntze, a Brazilian native forest species, was found to increase with faster growth and lower stocking, while decreasing from pith to bark. A complete randomised block design was planted with five blocks. Ten trees were harvested in each of three spacing treatments. We hypothesised that the stand stemwood production would not significantly differ depending on tree spacing. However, tree growth would be higher in the wider spacing and wood density would be higher in the narrower spacing. The diameter growth of trees was higher at 3 m × 2.5 m than at 3 m × 2 m and 3 m × 1.5 m. Nevertheless, this higher individual tree growth at 3 m × 2.5 m did not compensate for the greater tree stock density at 3 m × 1.5 m with stand stemwood production at 38 years of 530 m3 ha?1 and 649 m3 ha?1, respectively. These results suggest that C. legalis, which can produce up to 17 m3 ha?1 y?1 of medium-to high-density timber – about 800 kg m?3 – is a promising native species for forest plantations in Brazil.  相似文献   

20.
The effect of ash fertilization on height growth and volume production of Scots pine (Pinus sylvestris L.) was studied on oligotroph peatland in southeast Norway. In the year 1944, plots 15 m × 15 m size were fertilized with 0, 4, 7, and 10 tons ha?1 of wood or peat ash. The area was treeless, but a satisfactory number of pine seedlings were present. All measurements were confined to the central inner plot, 10 m × 10 m area. Most plots were re-fertilized with 10 tons of wood ash ha?1 in the year 1993. Wood ash had higher content of nutrients, and generally, it had greater growth enhancement effect than peat ash. When the amount of ash was increased, volume production significantly increased for the age period 38–50 years and the total production at age 50 years. The mean annual increment during the first 50 years was about 6 m3 ha?1 for the plots applied with 10 tons of ash ha?1. Trees on plots fertilized with 7 or 10 tons in 1944 and replenished with 10 tons ha?1 at age 50 years (1993) had a mean annual increment of 14 m3 ha?1 for the stand age period 51–68 years. Over time some tree roots from control plots and plots fertilized with 4 tons ha?1 have captured nutrients from richer plots. Such effect is to a smaller extent relevant for treatment 7 tons. It is concluded that the content of mineral nutrients of wood and peat ash makes these ashes well suited as fertilizers on peatland.  相似文献   

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