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The resistivity difference between oil and gas layers and the water layers in low contrast tight sandstone reservoirs is subtle. Fluid identification and saturation calculation based on conventional logging methods are facing challenges in such reservoirs. In this paper, a new method is proposed for fluid identification and saturation calculation in low contrast tight sandstone reservoirs. First, a model for calculating apparent formation water resistivity is constructed, which takes into account the influence of shale on the resistivity calculation and avoids apparent formation water resistivity abnormal values. Based on the distribution of the apparent formation water resistivity obtained by the new model, the water spectrum is determined for fluid identification in low contrast tight sandstone reservoirs. Following this, according to the average, standard deviation, and endpoints of the water spectrum, a new four-parameter model for calculating reservoir oil and gas saturation is built. The methods proposed in this paper are applied to the low contrast tight sandstone reservoirs in the Q4 formation of the X53 block and X70 block in the south of Songliao Basin, China. The results show that the water spectrum method can effectively distinguish oil-water layers and water layers in the study area. The standard deviation of the water spectrum in the oil-water layer is generally greater than that in the water layer. The new fourparameter model yields more accurate oil and gas saturation. These findings verify the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

The main objective of this study is to evaluate and identify the fluid behavior of the Zubair Formation in the Rumaila oilfield in southern Iraq using a nuclear magnetic resonance (NMR) log with petrophysical analysis. Through the integration of NMR logging with conventional open-hole logging (gamma Ray, resistivity, porosity logs), valuable additional data is provided for lithology and petrophysical parameter analysis, including porosity, permeability, pore size distribution, and fluid saturation, for wells (R-516, R-523, and Ru-382). The results indicate that the Zubair reservoir has good reservoir quality with high porosity and permeability values, and petrophysical log analysis results (gross thickness, net pay, and net/gross ratio) showed that the Zubair Formation can be divided into important reservoir units (D, F, L, and MN) with high movable hydrocarbons and low irreducible water saturation across all studied reservoir units, except for units (H and MN) in R-523 and Ru-382. The study confirms the high resolution of the NMR log, providing additional data while noting generally good borehole conditions, excluding intervals with washouts and shale layers, indicating that units have immovable hydrocarbons and reservoir water. Integrating the NMR log interpretation results with petrophysical interpretation, the Zubair reservoir was divided into different layers (oil, poor oil, water-flooded, tar, and dry). Fluid contacts in the Zubair reservoir are identified by combining the computer processing interpretation (CPI), NMR log, and reservoir saturation data. Pressure evaluation using formation pressure tests across Main Pay units is good for acquiring data, identifying fluids, and matching data with conventional logs. The correlation between the NMR-derived rock quality values (porosity and permeability) and conventional log data indicates that accurate results can be achieved by applying the NMR-modeled values. This study's findings confirm the importance of integrating NMR logs data and conventional logging results for the Zubair reservoir petrophysical analysis, where the NMR logs provide continuous estimates of producibility and permeability, along with direct data on bound fluids, which will optimize the evaluation of the Main Pay quality within the Zubair Formation. [ABSTRACT FROM AUTHOR]

As a country with a rich cultural and historical heritage, there are many grottoes in China. Unfortunately, many grottoes suffer from fracture seepage due to their age, causing weathering damage that requires prompt attention, detection, and repair to preserve them for future generations. In order to preserve the historical and cultural heritage of Beishan, Chongqing, China, this study illustrates how we assess the fracture seepage system of sandstone grottoes within the Penglaizhen Formation using multiple geophysical survey techniques. They are core data, conventional logging, borehole televiewer, and ground penetrating radar (GPR). Combining these methods, borehole televiewer and core data can improve the accuracy of conventional logging for stratigraphic delineation, as well as aid GPR in finding deep stratigraphic and seepage fractures. This study provides an effective routine to find sandstone grotto fractures and achieves positive results.

Studies relating to fish trophic ecology provide important insights regarding their life history. However, there is a lack of information linking fish diet composition with riparian cover in small streams. To investigate whether diet composition varied between streams with pristine and logged forests, I compared the food items consumed by four characid species: Bryconops melanurus, Moenkhausia collettii, Moenkhausia dichroura, and Moenkhausia oligolepis. I sampled 18 first‐order streams in the eastern Amazon: six with pristine forest, six with conventional logging, and six with selective logging. All fish species were classified as omnivorous, with diverse food categories recorded in their diets: mainly terrestrial insects for Moenkhausia species and aquatic insect nymphs for B. melanurus. However, the relative importance of each category varied only in streams with conventional logged forests. In these streams, all fish species consumed mainly autochthonous items, especially aquatic insect nymphs. In addition, terrestrial insects and seeds were absent in these streams with reduced riparian cover. In summary, this study highlighted that fish diet in conventional logged forests strongly differed from areas with pristine and selective logged forests. This finding states that managed forests may support a diverse diet for fish community, similar to that found in pristine forests. Therefore, management and conservation strategies of riparian vegetation in Amazonian streams are important to maintain habitat and food quality, which may be associated with a diverse diet for fish species. [ABSTRACT FROM AUTHOR]

Geologic interpretation results from conventional ground-penetrating radar (GPR) detection methods tend to have a certain degree of uncertainty. In order to improve the reliability of ground-penetrating radars in the detection of rock mass fissures in grottoes, this study proposes a ground-penetrating radar detection method with the logging data constraint, which is applied to detect the fractured rock mass in the Baodingshan Scenic Area of Dazu Rock Carvings, Chongqing, China. First, conventional logging and borehole televiewer data were compared and verified, yielding detailed lithological and wellbore fissure information. Next, electromagnetic wave velocity was calibrated using GPR profile and the depth of the stratigraphic interface determined by borehole data. Utilizing this calibrated velocity, we are able to accurately calculate the depth values of anomalies in GPR interpretation profiles. Subsequently, we compared the preliminary GPR interpretation profile with the borehole televiewer images. After eliminating false anomalies caused by interference, we obtained more reliable location information for detection targets such as fissures, fracture zones, and weak interlayers. The results of fissure detection in the Dazu Rock Carvings indicate that the detection results of ground-penetrating radar are verified and supplemented under the constraints of stratigraphic and well-wall fissure information obtained by logging. This effectively mitigates the influence of multiplicity and false anomalies of GPR detection on interpretation results. GPR with the logging data constraint enhances the accuracy of the fissure detection results, providing novel technical means for the protection and restoration of grotto relics. [ABSTRACT FROM AUTHOR]

Forest harvesting in the natural production forest management in Indonesia is mostly carried out using conventional logging techniques and causes serious damage to residual stands and soil resources. One of the efforts made to reduce this environmental damage is the application of reduced impact logging (RIL) techniques. This study aimed to collect and analyze research results related to the damage to residual stands caused by RIL in the natural production forest management in Indonesia. This study used a systematic review method. A systematic literature search was carried out at data sources such as Google Scholar, Research Gate, Science Direct, and SINTA, which were published between 1996-2021. All studies reported that applying RIL techniques can reduce the damage to the residual stands.

Geologic interpretation results from conventional ground-penetrating radar (GPR) detection methods tend to have a certain degree of uncertainty. In order to improve the reliability of ground-penetrating radars in the detection of rock mass fissures in grottoes, this study proposes a ground-penetrating radar detection method with the logging data constraint, which is applied to detect the fractured rock mass in the Baodingshan Scenic Area of Dazu Rock Carvings, Chongqing, China. First, conventional logging and borehole televiewer data were compared and verified, yielding detailed lithological and wellbore fissure information. Next, electromagnetic wave velocity was calibrated using GPR profile and the depth of the stratigraphic interface determined by borehole data. Utilizing this calibrated velocity, we are able to accurately calculate the depth values of anomalies in GPR interpretation profiles. Subsequently, we compared the preliminary GPR interpretation profile with the borehole televiewer images. After eliminating false anomalies caused by interference, we obtained more reliable location information for detection targets such as fissures, fracture zones, and weak interlayers. The results of fissure detection in the Dazu Rock Carvings indicate that the detection results of ground-penetrating radar are verified and supplemented under the constraints of stratigraphic and well-wall fissure information obtained by logging. This effectively mitigates the influence of multiplicity and false anomalies of GPR detection on interpretation results. GPR with the logging data constraint enhances the accuracy of the fissure detection results, providing novel technical means for the protection and restoration of grotto relics.

Volcanic rock reservoirs have received extensive attention from scholars all over the world because of their geothermal, mineral, and oil and gas resources. Shear wave velocity is the essential information for AVO (amplitude variation with offset) analysis and the reservoir description of volcanic rocks. However, due to factors such as cost, technical reasons, and so on, shear wave velocity is not provided in many logging data. This paper proposes a shear wave velocity prediction method suitable for the conventional logging of volcanic rocks. Firstly, the Xu–White model is improved. The probability distributions formed by the prior information of the logging area are used to initialize the key petrophysical parameters in the model instead of the fixed parameter value to establish the statistical petrophysical model between the logging curve and shear wave velocity. Then, based on the Bayesian inversion method, the simulated P-wave velocity is matched with the actual P-wave logging data to calculate the key petrophysical parameters, and is then used for S-wave velocity prediction. The method is applied to the actual logging data of the No. 5 structure in Nanpu Sag, eastern China. The prediction effect of shear wave velocity is better than that of the conventional method, indicating the feasibility and effectiveness of this method. This study will provide more accurate shear wave velocity data for the exploration and development of volcanic reservoirs. [ABSTRACT FROM AUTHOR]

Brittleness index is an important parameter for the exploration and development of tight sandstone reservoir. In this paper, a new method for calculating brittleness index using conventional logging data was established to find the high-quality exploration and development target area of tight sandstone reservoir in He8 Member of Permian in the western margin of the Ordos Basin. Firstly, the mineral composition and content of rock samples in the study area were analyzed by rock mineral X-ray diffraction, and the brittleness index was calculated according to the mineral content with the average of 70.85%. Then, three kinds of brittleness index logging prediction models were obtained by conventional logging curves such as natural gamma and compressional wave interval transit time. Each prediction model was corrected by the brittleness index calculated according to the X-ray diffraction experiment, and the correlation coefficients were 0.83, 0.58, and 0.71, respectively. Finally, through multiple regression, the comprehensive equation for brittleness index prediction was established by combining these three kinds of models. According to the example of the specific well in the study area, the brittleness index predicted by conventional logging is highly matched with the interpretation results of array acoustic logging with the correlation coefficient of 0.90, which means the accuracy of the comprehensive equation has been verified. The new method can evaluate reservoir brittleness by conventional logging data in the absence of rock sample test data and popularize the application of brittleness index in oil and gas field exploration and development.

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Pulsed neutron-neutron (PNN) logging is based on emitting neutrons into the near-wellbore zone and computing the neutron count decay due to scattering and capturing. The main application of this logging tool is to determine the current oil saturation and to detect channeling in perforated and non-perforated intervals behind the casing. Correct interpretation of the results obtained from PNN logging enables engineers to predict new perforation intervals in depleted reservoirs. This study examines the application of PNN logging in a well located in one of Iranian oil reservoirs. The interpretation procedure is described step by step. The principle of the PNN logging and the specifications of the tool are discussed and the applications of PNN logging in evaluation of oil saturation, identification of water flooded zones and prediction of potential perforating zones are described. Channeling is also investigated between all layers, good and poor oil zones are characterized based on the calculated oil saturations and new perforation intervals are suggested with the aim to boost oil production from the reservoir. The results of this study show that zones 1 to 5 having low oil saturations, are interpreted as depleted oil zones. Zones 6 to 8 are interpreted as good oil zones having high potential to produce oil. Zone 9 is interpreted as a water zone.

The aim of the present study was to evaluate how environments modified by conventional logging (CL), reduced-impacted logging (RIL), and pastures (PST) surrounding streams affect environmental characteristics and semiaquatic bugs assemblages (Gerromorpha), in the eastern Amazon. The following hypotheses were tested: (i) environmental heterogeneity in streams is lower in areas with more intensive practices (e.g. CL and PST); (ii) species richness and abundance are also lower in streams located in areas with more intensive practices, while more preserved areas have higher richness and abundance; and (iii) species composition shall be affected by changes in forestry practices, thus causing differences between treatments according to species tolerances. We observed that although PST and CL have higher environmental heterogeneity and alpha diversity, respectively, these treatments are associated with the presence of tolerant species and are different from the forest regarding composition (species identity) and species distribution pattern. On the other hand, forest and RIL areas did not have differences regarding habitat characteristics, environmental heterogeneity, alpha diversity, composition and species distribution pattern. This indicates that RIL can maintain a considerable part of habitat integrity and Gerromorpha assemblage composition. [ABSTRACT FROM AUTHOR]

We evaluated the effects of changes in habitat structure resulting from conventional logging (CL) and reduced-impact logging (RIL) on the ecomorphological structure of stream fish assemblages in the eastern Brazilian Amazon, investigating (1) which habitat characteristics are influenced by different logging methods, (2) the differences in the ecomorphological structure of fish assemblages between two logging methods and undisturbed forest (UF), and (3) the relationships between ecomorphological traits of fish assemblages and habitat variables. We measured 13 habitat variables and characterized 11 ecomorphological traits of 55 fish species collected in 34 sampling sites (stream stretches) located in CL, RIL, and UF. In logged areas, the streams present a fine sediment increase and reduced vegetation cover, while in the UF a greater amount of natural shelter and more cover vegetation were observed. These environmental changes selected ecomorphological traits of stream fish assemblages, recording a greater relative width of the mouth in UF, higher ventral flattening index in RIL, or greater relative head length, and higher caudal peduncle compression index in CL. In this sense, we recommend that logging practices, including RIL, should be reviewed as a means of adopting better strategies to minimize human disturbances in streams. [ABSTRACT FROM AUTHOR]

Volcanic rock reservoirs have received extensive attention from scholars all over the world because of their geothermal, mineral, and oil and gas resources. Shear wave velocity is the essential information for AVO (amplitude variation with offset) analysis and the reservoir description of volcanic rocks. However, due to factors such as cost, technical reasons, and so on, shear wave velocity is not provided in many logging data. This paper proposes a shear wave velocity prediction method suitable for the conventional logging of volcanic rocks. Firstly, the Xu–White model is improved. The probability distributions formed by the prior information of the logging area are used to initialize the key petrophysical parameters in the model instead of the fixed parameter value to establish the statistical petrophysical model between the logging curve and shear wave velocity. Then, based on the Bayesian inversion method, the simulated P-wave velocity is matched with the actual P-wave logging data to calculate the key petrophysical parameters, and is then used for S-wave velocity prediction. The method is applied to the actual logging data of the No. 5 structure in Nanpu Sag, eastern China. The prediction effect of shear wave velocity is better than that of the conventional method, indicating the feasibility and effectiveness of this method. This study will provide more accurate shear wave velocity data for the exploration and development of volcanic reservoirs.

Abstract The non-availability of the advanced tools such as FMI and Borehole Televiewer has led to the use of conventional well logging methods in the examination of potential fractures and ultimately help in reservoir characterization and development. This study uses the said conventional well log data for fracture detection in the Upper Cretaceous Matulla Limestone Formation in the Geisum oil field, southern Gulf of Suez province, Egypt. Different applications have therefore been integrated together, which include the Secondary Porosity Index (SPI) with tri-porosity crossplot (M–N), the natural gamma ray spectroscopy (NGS), the Dual Laterolog–MSFL logs separation, the litho-density and compensated neutron logs and the Variable Density log (VDL), which is based on the responses of the compressional and shear waves in front of fractured zones. Good secondary porosity is prevalent in the Matulla Formation with SPI values reaching maximum values of 21.5 and 15.1% in the studied wells. Three and six fractured zones have been recognized in Geisum A-2 and Tawila N-1 wells, respectively, based on SPI logs. Several of these proposed zones are supported by other tools such as NGS, photoelectric (Pe), and VDL and fracturability Index (FI). This integrated method using various conventional well log has produced results suggesting great probability in fracture identification in the carbonate Matulla Formation.

The hill dipterocarp forest (HDF) in the Ulu Muda Forest Reserve was logged under supervised logging (SLo)(Compartment 25A) and conventional logging (CL) (Compartment 28A) 14 and 16 years ago, respectively. A systematic sampling layout was used to assess forest recovery after supervised and conventional loggings. In 60 subplots (50 m × 20 m) all stems with DBH ≥ 1 cm were enumerated, measured and identified. Data were compared between SLo and CL in order to assess forest recovery after logging. In terms of species composition 468 species belonging to 198 genera and 68 families were recorded. The tree species composition of the study sites contributed to 16.5%, 38.6% and 68.0% of the total tree species, genera and families found in Peninsular Malaysia; of these 57 are endemic including four rare species and one very rare species. Four new records for Kedah, Diospyros apiculata, Macaranga recurvata, M. constricta and Cryptocarya bracteolata were found. The forests are still rich in biodiversity; this is shown by Margalef index of SLo and CL sites of 49.58 and 33.38, respectively. Shannon-Weiner, Simpson and Fisher indices for SLo and CL sites were 5.44 and 4.89, 151.4 and 84.5, and 119.7 and 70.36, respectively. Smith and Wilson evenness values of SLo and CL sites were 0.46 and 0.38, respectively. The difference between diversity indices of SLo and CL sites were significant at 5% level. Sorensen and Jaccard similarity indices between SLo and CL sites were 0.60 and 0.43, respectively. In terms of species composition and diversity, the SLo site recovered three times more than CL site which was 46.5% and 14.3%, respectively. Aboveground biomass, belowground biomass, total biomass and total carbon were much higher in SLo which were 282.8, 76.4, 359.2, 179.6 t ha-1 while CL gave values of 216.7, 58.5, 275.2, 137.6 t ha-1, respectively. The recovery of biomass in SLo was 23.4% higher than CL site although the difference was non-significant (Sig. = 0.19 and α = 0.05). [ABSTRACT FROM AUTHOR]

Illegal logging is widely believed to have a greater adverse impact on the forest resource base of many countries, but field studies comparing activities of illegal loggers with their conventional counterparts are few, with some not supporting this general notion. We conducted field assessments in Krokosua Hills Forest Reserve in Juaboso district of Ghana to compare operations of illegal chainsaw millers with conventional loggers in relation to species felled, adherence to regulation on minimum felling diameter, extent of collateral damage at stump site and regard for protection of water bodies in the reserve. We found a total of 139 felled trees belonging to 17 species. Felling by Illegal chainsaw millers constituted 37.4% of total felling. 94% of all trees felled by illegal loggers were below minimum felling diameter and were mainly class 1 species with scarlet star rating (and including species regarded as depleted in Ghanaian forests). By contrast, conventional loggers felled from a wider range of species and conservation priorities with 59% of felling done below minimum felling diameter. Collateral damage at stump site was higher for conventional than illegal loggers, with damage to residual stems being mainly broken stems. Average distance of stump sites to nearest water bodies was 24.2 ± 16.7m for conventional loggers, significantly greater than distance for illegal loggers at 15.2 ± 9.7m, suggesting that illegal loggers were felling closer to water bodies. Findings in this study have important implications for forest resource conservation. [ABSTRACT FROM AUTHOR]

Despite the widespread use and strong promotion of the sustainable forest management approach, there are still uncertainties about the actual contribution of current forest management practices to sustainability. We studied the problem of sustainable timber production in four tropical countries (Belize, Guyana, Suriname, and Trinidad and Tobago). Data assessed on experimental plots covering 10 km2 were used to compare management practices of four forest tenure types that commonly exist in the study countries: large scale concessions (LSC), private forests (PR), periodic block system forests (PBS), and community managed forests (CM). As an indicator of sustainable timber production, we calculated the recovery times expected under the initial condition of the stands and compared them with currently practiced cutting cycles. Three growth scenarios were simulated using diameter growth rates (1.6/2.7/4.5 mm year−1) from empirical data from studies in the region. Initial volumes were determined for all commercial trees as well as for commercial trees with a DBH-threshold ≥45 cm. Highest initial volumes were found in LSC and PBS managed forests. Lowest volumes were found in CM and PR forests. Assuming the lowest growth rate for all commercial trees, none of the stands studied reached the initial pre-harvest volumes within the currently practiced cutting cycles. Assuming the highest growth rate for all trees, LSC, PBS, and PR forests reach the initial pre-harvest volume. Looking at the subset of commercial trees with a DBH ≥45 cm, all stands will reach the initial volume within 30 years only if the highest growth rate is assumed. We show that general harvest codes do not guarantee sustainable forest management in the tropics. Local stand conditions must always be one of the guiding principles of sustainable timber utilization. Applying the rigid rules, which do not take into account the current conditions of the stands, entails long-term risk of forest degradation.

In order to make full use of well logging information to accurately predict the fracture distribution of carbonate reservoir, we use several log curves to comprehensively identify and delineate the structural fractures, dissolved fractures and sutured fractures of different occurrences, scales and geneses in the North Truwa oilfield of the Pre-Caspian Basin in Kazakhstan. The resistivity differenceratio method may be used to identify high-angle fractures. The 3-porosity ratio method, which tends to be affected by dissolved pores and vugs, is applicable to low-angle fractures and microfractures. By using each single method separately, only 54.8% of fractures on the average may be identified. The comprehensive probability density method which integrates the above two methods improves the accuracy of fracture identification to 73.6% as per the validation of core and imaging logging data. Fracture distribution in the study area is dominated by sedimentation, structure and diagenesis. In the lateral direction, the structural highs and areas with intense karstification may demonstrate high fracture probability density and thus areinterpreted to be rich in structural and dissolved fractures. In the vertical direction, more fractures may occur in the brittle intervals with small shale and gypsum contents. The results of fracture prediction are consistent with the sedimentary diagenesis of carbonate reservoirs, indicating that the method is feasible to predict the fracture. [ABSTRACT FROM AUTHOR]

The non-availability of the advanced tools such as FMI and Borehole Televiewer has led to the use of conventional well logging methods in the examination of potential fractures and ultimately help in reservoir characterization and development. This study uses the said conventional well log data for fracture detection in the Upper Cretaceous Matulla Limestone Formation in the Geisum oil field, southern Gulf of Suez province, Egypt. Different applications have therefore been integrated together, which include the Secondary Porosity Index (SPI) with tri-porosity crossplot ( M- N), the natural gamma ray spectroscopy (NGS), the Dual Laterolog-MSFL logs separation, the litho-density and compensated neutron logs and the Variable Density log (VDL), which is based on the responses of the compressional and shear waves in front of fractured zones. Good secondary porosity is prevalent in the Matulla Formation with SPI values reaching maximum values of 21.5 and 15.1% in the studied wells. Three and six fractured zones have been recognized in Geisum A-2 and Tawila N-1 wells, respectively, based on SPI logs. Several of these proposed zones are supported by other tools such as NGS, photoelectric (Pe), and VDL and fracturability Index (FI). This integrated method using various conventional well log has produced results suggesting great probability in fracture identification in the carbonate Matulla Formation. [ABSTRACT FROM AUTHOR]

Timber harvest is a prevailing economic activity in Amazonia, which contributes to forest degradation and biodiversity loss. However, Reduced-impact logging has been used to mitigate the loss of environmental integrity and biodiversity, since it has been assumed to be less detrimental than conventional logging practices. The objective of this study was to evaluate if environmental conditions, streams and Odonata communities in reduced-impact logging areas (RIL) are similar to those of unlogged areas (CONTROL), whilst all are modified in conventional logging areas (CL), as a consequence of vegetation removal from the margins of water bodies. Forty-nine streams in areas that differ in timber harvest practices were sampled in eastern Amazonia. As expected, aquatic systems in RIL areas showed environmental conditions and Odonata species composition similar to CONTROL areas while CL streams differed both from CONTROL and RIL. Odonata richness and abundance were not different between CONTROL, RIL and CL treatments, however. Despite the fact that species richness and abundance changes may be masked by the presence of remaining riparian vegetation in CL areas, the use of reduced-impact logging minimizes changes in Odonata species composition and environmental conditions, that remain similar to that of unlogged areas. This is possible due to the planning to reduce environmental impacts in RIL. Unlike RIL, most canopy cover in the proximity of the water bodies (<10 m distance) is lost in CL areas due to logging activities. [ABSTRACT FROM AUTHOR]

The effectiveness of reduced-impact logging practices on the maintenance of biodiversity in Borneo has been recognized for some organisms (e.g., mammals). We investigated the effects of reduced-impact logging and conventional selective logging practices on biodiversity by using soil fauna as indicators of disturbance. The study sites were the production forests of the Deramakot Forest Reserve and the Tangkulap Forest Reserve in Sabah, Malaysian Borneo (5°14–30′ N, 117°11–36′ E). We compared macro- and mesofauna in a pristine forest with no logging, a reduced-impact logged forest in Deramakot Forest Reserve, and a conventionally logged forest in Tangkulap Forest Reserve. The mean density of soil macrofauna (excluding ants) did not differ significantly among the three forest categories (nested ANOVA, p > 0.05). This tendency was also seen in the density and species richness of Oribatida and Collembola, which showed little difference among forest categories. Nonmetrical multidimensional scaling (NMS) ordination diagrams revealed a different community composition in conventionally logged forest sites compared with the other sites. The scores for the NMS first or second axis of soil fauna were correlated with one or more of the values for density, diversity, and species composition of trees. A RELATE test showed the congruence between trees and the Collembola and Oribatida community composition between sites. The results implied that the soil fauna community composition was related to tree communities. In conclusion, the impacts of logging on decomposers in the soil animal communities have been mitigated by the introduction of reduced-impact logging in Deramakot Forest Reserve through the protection of tree vegetation. It is important to consider monitoring the influence of selective logging on soil fauna with regard to the dynamics of the species (or group) composition because total density and species (or group) richness of soil fauna displayed only a marginal response to the different logging practices. [ABSTRACT FROM AUTHOR]

Forest management certification is assumed to promote sustainable forest management, but there is little field-based evidence to support this claim. To help fill this gap, we compared a Forest Stewardship Council (FSC)-certified with an adjacent uncertified, conventionally logged concession (CL) in Gabon on the basis of logging damage, above-ground biomass (AGB), and tree species diversity and composition. Before logging, we marked, mapped, and measured all trees >10 cm dbh in 20 and twelve 1-ha permanent plots in the FSC and CL areas, respectively. Soil and tree damage due to felling, skidding, and road-related activities was then assessed 2-3 months after the 508 ha FSC study area and the 200 ha CL study area were selectively logged at respective intensities of 5.7 m/ha (0.39 trees/ha) and 11.4 m/ha (0.76 trees/ha). For each tree felled, averages of 9.1 and 20.9 other trees were damaged in the FSC and CL plots, respectively; when expressed as the impacts per timber volume extracted, the values did not differ between the two treatments. Skid trails covered 2.9 % more of the CL surface, but skid trail length per unit timber volume extracted was not greater. Logging roads were wider in the CL than FSC site and disturbed 4.7 % more of the surface. Overall, logging caused declines in AGB of 7.1 and 13.4 % at the FSC and CL sites, respectively. Changes in tree species composition were small but greater for the CL site. Based on these findings and in light of the pseudoreplicated study design with less-than perfect counterfactual, we cautiously conclude that certification yields environmental benefits even after accounting for differences in logging intensities. [ABSTRACT FROM AUTHOR]

The effects of proximity to felling gaps on residual trees in a selectively logged forest were monitored for eight years after nine 4-ha plots (n = 3 per treatment) were subjected to one of two intensities of reduced-impact logging (RIL), i.e. either 50 or 60 cm diameter cutting limits, or conventional logging of 60 cm diameter cutting limit with three additional plots reserved as unlogged controls. Each residual tree > 10 cm diameter at breast height (dbh) was classified as either being near (< 20 m from a gap centre) or far (> 20 m) from the nearest felling gap, defined as 20 m radii areas around the stumps of felled trees. Tree mortality rates did not vary with gap proximity, but were higher in logged than unlogged plots for the first two years after logging. In all logged plots combined, trees < 50 cm dbh of all species and dipterocarps < 30 cm dbh grew faster if they were near a gap. The observed increased growth rates of trees in the more intensively logged plots, regardless of the logging method used, was due to both higher proportions of trees near gaps and faster growth of trees in all locations. [ABSTRACT FROM AUTHOR]

If global policies intended to promote forest conservation continue to use the definition of “forest” adopted in 2001 by the United Nations Framework Convention on Climate Change (an area of >0.05–1 ha with >10–30% cover of plants >2–5 m tall at maturity), great quantities of carbon and other environmental values will be lost when natural forests are severely degraded or replaced by plantations but technically remain “forests.” While a definition of “forest” that is globally acceptable and appropriate for monitoring using standard remote sensing options will necessarily be based on a small set of easily measured parameters, there are dangers when simple definitions are applied locally. At the very least, we recommend that natural forest be differentiated from plantations and that for defining “forest” the lower height limit defining “trees” be set at more than 5 m tall with the minimum cover of trees be set at more than 40%. These changes will help reduce greenhouse gas emissions from what is now termed forest “degradation” without increasing monitoring costs. Furthermore, these minor changes in the definition of “forest” will promote the switch from degradation to responsible forest management, which will help mitigate global warming while protecting biodiversity and contributing to sustainable development. [ABSTRACT FROM AUTHOR]

A comparison of landslide rates following helicopter and conventional, cable-based, clear-cut logging was carried out using results from two independent terrain attribute studies in the Eldred and Lois River watersheds in the Southwest Coast Mountains of British Columbia. Landslides initiating from directly within a road prism were excluded from the study in order to focus the comparison on landslides related primarily to conventional versus helicopter yarding methods. A landslide rate of 0.02 landslides/ha was observed in 162 terrain polygons logged by helicopter ∼8 years prior to this study. Landslide rates in 38 gullied polygons were 0.06 landslides/ha. No landslides were observed in 124 open-slope polygons. Over a similar 8-year average period, 0.03 landslides/ha were observed in 142 cable-yarded terrain polygons; 0.06 and 0.02 landslides/ha occurred in gullied and open-slope polygons, respectively. t-Tests indicate that total landslide rates are not significantly different following helicopter and conventional logging; however, a dichotomy exists between gullied and open-slope terrain polygons. Landslide rates are not significantly different in gullied terrain but are significantly higher on open-slopes following conventional cable logging. Consequently, landslides appear to have a greater potential to occur in open-slope terrain following conventional logging, but differences in gullied polygons are less likely. Increased post-logging landslide rates in conventionally logged, open slopes are more likely the result of undetected road-related drainage changes than differences between helicopter and conventional yarding-related ground disturbance. [Copyright &y& Elsevier]

Global efforts have been made to manage tropical forests for timber production and climate change mitigation. This study assessed carbon emission reductions through the improved forest management and the substitution of fossil fuels with wood biomasses under the conventional (CVL) and reduced impact logging (RIL) systems in Southeast Asia between 2000 and 2060. During this period, carbon emissions from logging and deforestation in the region were approximately 10% of carbon emissions from tropical deforestation. By adopting the RIL, 96.6 Tg CO 2 of emissions can be reduced, while producing 35.1 million m3 year−1 of wood products. If woody biomasses are used to substitute the combustion of coal, diesel, or natural gas for bioenergy production, total emission reductions could be 229.9, 215.4, or 207.9 Tg CO 2 annually during the Paris Agreement, respectively. Depending on chosen carbon price, management of natural forests in Southeast Asia could generate about US$2.1–2.3 billion annually over 10 years between 2020 and 2030. Although costs for bioenergy production from wood biomass remain the concern, enabling global policies, emerging sustainability markets, and financial incentives through carbon tax, environmental tax, and energy tax could materialize the sound management of tropical forests for long-term timber production and climate change mitigation. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, wood extract production and costs were assessed in the planned and unplanned (conventional) logging system. The research was carried out in compartments No. 23 and 25 of second district of Nave-Asalem forest. Work study technique based on IUFRO guideline was used to calculate system hourly production. Based on guideline of Forest, Range and Watershed Organization (FRWO) of Iran, system hourly cost was calculated. Results showed that planning skid trails and landings before tree felling as well as using directional felling technique increased hourly skidder production from 12.72m3 to 18.8m3. Increase of production, reduced the extraction cost from 103015 to 69372 Rials per cubic meter. These extraction costs include landing construction costs in planned harvesting and road maintenance costs in unplanned logging system.

Despite the widespread use and strong promotion of the sustainable forest management approach, there are still uncertainties about the actual contribution of current forest management practices to sustainability. We studied the problem of sustainable timber production in four tropical countries (Belize, Guyana, Suriname, and Trinidad and Tobago). Data assessed on experimental plots covering 10 km2 were used to compare management practices of four forest tenure types that commonly exist in the study countries: large scale concessions (LSC), private forests (PR), periodic block system forests (PBS), and community managed forests (CM). As an indicator of sustainable timber production, we calculated the recovery times expected under the initial condition of the stands and compared them with currently practiced cutting cycles. Three growth scenarios were simulated using diameter growth rates (1.6/2.7/4.5 mm year−1) from empirical data from studies in the region. Initial volumes were determined for all commercial trees as well as for commercial trees with a DBH-threshold ≥45 cm. Highest initial volumes were found in LSC and PBS managed forests. Lowest volumes were found in CM and PR forests. Assuming the lowest growth rate for all commercial trees, none of the stands studied reached the initial pre-harvest volumes within the currently practiced cutting cycles. Assuming the highest growth rate for all trees, LSC, PBS, and PR forests reach the initial pre-harvest volume. Looking at the subset of commercial trees with a DBH ≥45 cm, all stands will reach the initial volume within 30 years only if the highest growth rate is assumed. We show that general harvest codes do not guarantee sustainable forest management in the tropics. Local stand conditions must always be one of the guiding principles of sustainable timber utilization. Applying the rigid rules, which do not take into account the current conditions of the stands, entails long-term risk of forest degradation. [ABSTRACT FROM AUTHOR]

Using insights from the forest ecology literature, we analyze the effect of injured trees on stand composition and carbon stored in above‐ground biomass and the implications for forest management decisions. Results from a Faustmann model with data for a tropical forest on Kalimantan show that up to 50% of the basal area of the stand before harvest can consist of injured trees. Considering injured trees leads to an increase in the amount of carbon in above‐ground biomass of up to 165%. These effects are larger under reduced impact logging than under conventional logging. The effects on land expectation value and cutting cycle are relatively small. The results suggest that considering injured trees in models for tropical forest management is important for the correct assessment of the potential of financial programs to store carbon and conserve forest ecosystem services in managed tropical forests, such as reducing emissions from deforestation and forest degradation and payment for ecosystem services. Recommendations for Resource ManagersConsidering the role of injured trees is important for managing tropical forestsThese trees can cover up to 50% of basal area and contain more than 50% of the carbon stored in above‐ground biomassReduced impact logging leads to a larger basal area of injured trees and more carbon stored in injured trees than conventional loggingInjured trees play an important role when assessing the potential for carbon storage in the context of payment for forest ecosystem services. [ABSTRACT FROM AUTHOR]