Forest Conversion (forest + conversion)

Distribution by Scientific Domains

Selected Abstracts

Forest Conversion and Degradation in Papua New Guinea 1972,2002

BIOTROPICA, Issue 3 2009
Phil L. Shearman
ABSTRACT Quantifying forest change in the tropics is important because of the role these forests play in the conservation of biodiversity and the global carbon cycle. One of the world's largest remaining areas of tropical forest is located in Papua New Guinea. Here we show that change in its extent and condition has occurred to a greater extent than previously recorded. We assessed deforestation and forest degradation in Papua New Guinea by comparing a land-cover map from 1972 with a land-cover map created from nationwide high-resolution satellite imagery recorded since 2002. In 2002 there were 28,251,967 ha of tropical rain forest. Between 1972 and 2002, a net 15 percent of Papua New Guinea's tropical forests were cleared and 8.8 percent were degraded through logging. The drivers of forest change have been concentrated within the accessible forest estate where a net 36 percent were degraded or deforested through both forestry and nonforestry processes. Since 1972, 13 percent of upper montane forests have also been lost. We estimate that over the period 1990,2002, overall rates of change generally increased and varied between 0.8 and 1.8 percent/yr, while rates in commercially accessible forest have been far higher,having varied between 1.1 and 3.4 percent/yr. These rates are far higher than those reported by the FAO over the same period. We conclude that rapid and substantial forest change has occurred in Papua New Guinea, with the major drivers being logging in the lowland forests and subsistence agriculture throughout the country with comparatively minor contributions from forest fires, plantation establishment, and mining. RESUMEN Sopos long kisim gutpela save long senis i kamak long tropics em i wanpela bik pela samting long wanem, bikpela bus em wanpela hap we wok konsevason na carbon cycle bai inap kirapim gutpela wok. Insait long olgeta hap long world, PNG em wanpela hap we bikpela bus em i stap yet. Insait long dispela wok mipela soim olsem bikpela senis em i kamap long insait long bikpela bus na long hamas bikpela bus yumi gat. Nogat wanpela kain wok painimaut emi painim dispela senis bipo. Mipela lukluk gut long we olgeta bikpela bus i raus na we bus i kisim bagarap insait long, yia 1972 i kamap inap long yia 2002. Long yia 1972 mipela i usim map ol i kolim land cover map na long yia 2002 mipela lukluk long olgeta PNG high-resolution satellite imagery. Long yia 2002, 28,251,967 hectares bikpela bus i stap insait long Papua New Guinea. Long namel long 1972 igo inap long 2002, Papua New Guinea i lusim 15 percent long algeta bipela bus belong en. Insait long dispela 15 percent, 8.8 percent em i kamap bikos ol lain i katim diwai long salim. As bilong senisim bikela bus emi stap long ples we igat bikpela diwai long katim. Insait long dispela hap yumi lusim 36 percent, sampela we yumi inap long salim, tasol narapela emi bikos yumi rausim bus long wokim gaden or narapela kainkain pasin yumi wokim. Long 1972 i kamap inap long yia 2002, yumi lusim 13 percent long bikpela bus raonim ol bikpela maunten. Mipela painim olsem, long yia 1990 igo inap long yia 2002, long algeta kantri kain senis i wok long kamap bikpla. Senis istap insait long 0.8 igo inap long 1.8 percent long wan wan yia, tasol insait long wan wan liklik hap some pela i kisim bikpela senis, na ol narapela ino tumas. Long ol hap igat gutpela diwai long katim, senis i stat long 1.1 percent igo inap 3.4 percent. Dispela senis em i winim estimates we ol lain FAO i bin tokaut long em bipo. Long dispela wok painimaut, mipela iken tok olsem, as bilong dispela bikpela senis emi kamap long wanem ol i rausim na bagarapim bikpela bus. Dispela asua i kamap taim yumi rausim planti diwai tumas long salim na sampela taim yumi katim bus long wokim garden. Sampela taim bikpela paia tu i save kukim bikpela bus. [source]

Effects of Conversion of Dry Tropical Forest to Agricultural Mosaic on Herpetofaunal Assemblages

atributos de vulnerabilidad; bosque tropical seco; ensambles herpetofaunísticos; modificación del hábitat; mosaico agrícola Abstract:,We explored the impact of forest conversion to agricultural mosaic on anuran, lizard, snake, and turtle assemblages of Neotropical dry forests. Over 2 years, we sampled 6 small watersheds on the west coast of Mexico, 3 conserved and 3 disturbed. The disturbed watersheds were characterized by a mosaic of pastures and cultivated fields (corn, beans, squash) intermingled with patches of different successional stages of dry forest. In each watershed, we conducted 11 diurnal and nocturnal time-constrained searches in 10 randomly established plots. We considered vulnerability traits of species in relation to habitat modification. Eighteen anuran, 18 lizard, 23 snake, and 3 turtle species were recorded. Thirty-six species (58%) occurred in both forest conditions, and 14 (22%) and 12 species (19%) occurred only in the conserved and disturbed sites, respectively. Assemblages responded differently to disturbance. Species richness, diversity, and abundance of lizards were higher in disturbed forests. Anuran diversity and species richness were lower in disturbed forest but abundance was similar in both forest conditions. Diversity, richness, and abundance of turtles were lower in disturbed forest. The structure and composition of snake assemblages did not differ between forest conditions. We considered species disturbance sensitive if their abundance was significantly less in disturbed areas. Four anuran (22%), 2 lizard (11%), and 3 turtle (100%) species were sensitive to disturbance. No snake species was sensitive. The decline in abundance of disturbance-sensitive species was associated with the reduction of forest canopy cover, woody stem cover, roots, and litter-layer ground cover. Anuran species with small body size and direct embryonic development were especially sensitive to forest disturbance. An important goal for the conservation of herpetofauna should be the determination of species traits associated with extinction or persistence in agricultural mosaics. Resumen:,Exploramos el impacto de la conversión de bosques a mosaico agrícola sobre ensambles de lagartijas, serpientes y tortugas de bosques Neotropicales secos. Durante 2 años muestreamos 6 cuencas pequeñas, 3 conservadas y 3 perturbadas, en la costa occidental de México. Las cuencas perturbadas se caracterizaron por un mosaico de pastizales y campos cultivados (maíz, frijol, calabaza) entremezclados con parches de bosque seco en diferentes etapas sucesionales. En cada cuenca, realizamos 11 búsquedas diurnas y nocturnas en 10 parcelas establecidas aleatoriamente. Consideramos los atributos de vulnerabilidad de especies en relación con la modificación del hábitat. Registramos 18 especies de lagartijas, 23 de serpientes y 3 de tortugas. Treinta y seis especies (58%) ocurrieron en ambas condiciones de bosque, y 14 (22%) y 12 (19%) especies solo ocurrieron en los sitios conservados y perturbados, respectivamente. Los ensambles respondieron a la perturbación de manera diferente. La riqueza de especies, la diversidad y la abundancia de lagartijas fueron mayores en los bosques perturbados. La diversidad y riqueza de especies de anuros fueron menores en el bosque perturbado pero la abundancia fue similar en ambas condiciones de bosque. La diversidad, riqueza de especies y abundancia de tortugas fueron menores en el bosque perturbado. La estructura y la composición de los ensambles de serpientes no difirieron entre condiciones de bosque. Consideramos que las especies eran sensibles a la perturbación si su abundancia fue significativamente menor en las áreas perturbadas. Cuatro (22%) especies de anuros, 2 (11%) de lagartijas y 3 (100%) de tortugas fueron sensibles a la perturbación. Ninguna especie de serpiente fue sensible. La declinación en la abundancia de especies sensibles a la perturbación se asoció con la reducción en la cobertura del dosel, de tallos leñosos, raíces y hojarasca. Las especies de anuros de cuerpo pequeño y desarrollo embrionario directo fueron especialmente sensibles a la perturbación del bosque. La determinación de atributos de las especies asociadas con su extinción o persistencia en mosaicos agrícolas debería ser una meta importante para la conservación de la herpetofauna. [source]

Cacao boom and bust: sustainability of agroforests and opportunities for biodiversity conservation

Yann Clough
Abstract Cacao cultivation holds a sweet promise, not only for chocolate consumers and cacao farmers but also for conservationists who argue that diverse cacao agroforests may be used to sustain both livelihoods of smallholders and ecological benefits such as the conservation of biodiversity within human-dominated tropical landscapes. However, regional boom-and-bust cycles are the rule in global cacao production: after initial forest conversion to cacao agroforests, sustaining production is difficult due to dwindling yields as trees age and pest and disease pressure increases. The failure to revitalize plantations often leads to a shift of cacao production to other regions. Shade removal dynamics within these cycles substantially reduce most of the biodiversity benefits. We investigate the conservation implications of these processes. Using examples from the current cacao crisis in Indonesia, we show that until now commitments to sustainability by the cacao-chocolate sector have not been successful, which endangers remaining forests. Conservation can be combined with smallholder cacao production, but if this is to be achieved, greater quantitative and qualitative efforts to halt cacao cycles are needed on the part of the industry by making use of existing opportunities to combine sustainability, carbon storage, and biodiversity conservation. [source]

Is the forest conversion to pasture affecting the hydrological response of Amazonian catchments?

Signals in the Ji-Paraná Basin
Abstract It is well known that land use and land-cover changes (LUCC), particularly deforestation, have the potential to modify the hydrological response. Although those signals are relatively well documented in worldwide microcatchment studies, conflicting results reported in literature indicate that those signals can be sometimes difficult to detect and isolate in basins at larger scales. In order to detect signals in the hydrological response potentially, related to LUCC, streamflow records from Ji-Paraná Basin located in SW Amazonia are analysed in conjunction with deforestation maps derived from remote sensors. The basin has a drainage area greater than 30 000 km2 and has been through severe LUCC in the last decades. Statistical descriptors of daily streamflow series were correlated with landscape indices using non-parametric methodologies. To take into account scale effects, statistical analyses were repeated in different sub-basins. Results showed that the impact of LUCC on the hydrological response is time lagged at larger scales. The flow paths are clearly affected, depending on basin characteristics such as topography. In general, LUCC impacts lead to higher peak streamflows, the reduction of minimal values and the increment of stormflow. In agreement with previous studies, the detection of signals associated with LUCC was clearly detected at the smallest basin, but proved to be difficult at larger scales, suggesting the existence of non-linear effects, which aggregate across scale compensating small scale effects. Such behaviour indicates a challenge for mathematical models, which are usually developed to represent immediate hydrological response to basin wide LUCC. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Hydrological impacts of forest conversion to agriculture in a large river basin in northeast Thailand

J. Wilk
Abstract Small-scale experiments have demonstrated that forest clearance leads to an increase in water yield, but it is unclear if this result holds for larger river basins (>1000 km2). No widespread changes in rainfall totals and patterns were found in the 12 100 km2 Nam Pong catchment in northeast Thailand between 1957 and 1995, despite a reduction in the area classified as forest from 80% to 27% in the last three decades. Neither were any detectable changes found in any other water balance terms nor in the dynamics of the recession at the end of the rainy season. When a hydrological model calibrated against data from the period before the deforestation was applied for the last years of the study period (1987,1995), runoff generation was however underestimated by approximately 15%, indicating increased runoff generation after the deforestation. However, this was mainly due to the hydrological response during one single year in the first period, when the Q/P ratio was very low. When excluding this year, neither analysis based on the hydrological model could reveal any significant change of the water balance due to the deforestation. More detailed land-use analysis revealed that shade trees were left on agricultural plots as well as a number of abandoned areas where secondary growth can be expected, which is believed to account for the results. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Soil biochemical and chemical changes in relation to mature spruce (Picea abies) forest conversion and regeneration

Zheke Zhong
Abstract To investigate soil changes from forest conversion and regeneration, soil net N mineralization, potential nitrification, microbial biomass N, L-asparaginase, L-glutaminase, and other chemical and biological properties were examined in three adjacent stands: mature pure and dense Norway spruce (Picea abies (L.) Karst) (110 yr) (stand I), mature Norway spruce mixed with young beech (Fagus sylvatica) (5 yr) (stand II), and young Norway spruce (16 yr) (stand III). The latter two stands were converted or regenerated from the mature Norway spruce stand as former. The studied soils were characterized as having a very low pH value (2.9 , 3.5 in 0.01 M CaCl2), a high total N content (1.06 , 1.94,%), a high metabolic quotient (qCO2) (6.7 , 16.9 g CO2 kg,1 h,1), a low microbial biomass N (1.1 , 3.3,% of total N, except LOf1 at stand III), and a relatively high net N mineralization (175 , 1213 mg N kg,1 in LOf1 and Of2, 4 weeks incubation). In the converted forest (stand II), C,:,N ratio and qCO2 values in the LOf1 layer decreased significantly, and base saturation and exchangeable Ca showed a somewhat increment in mineral soil. In the regenerated forest (stand III), the total N storage in the surface layers decreased by 30,%. The surface organic layers (LOf1, Of2) possessed a very high net N mineralization (1.5 , 3 times higher than those in other two stands), high microbial biomass (C, N), and high basal respiration and qCO2 values. Meanwhile, in the Oh layer, the base saturation and the exchangeable Ca decreased. All studied substrates showed little net nitrification after the first period of incubation (2 weeks). In the later period of incubation (7 , 11 weeks), a considerable amount of NO3 -N accumulated (20 , 100,% of total cumulative mineral N) in the soils from the two pure spruce stands (I, III). In contrast, there was almost no net NO3 -N accumulation in the soils from the converted mixed stand (II) indicating that there was a difference in microorganisms in the two types of forest ecosystems. Soil microbial biomass N, mineral N, net N mineralization, L-asparaginase, and L-glutaminase were correlated and associated with forest management. Chemische und biochemische Veränderungen der Bodeneigenschaften durch Verjüngung und Waldumbau eines Fichtenaltbestandes Um die durch den Waldumbau und die Regeneration bedingten Standortsveränderungen zu untersuchen, wurden die Netto-Stickstoffmineralisierung, die potenzielle Nitrifikation, der mikrobiell gebundene Stickstoff (Nmic), L-Asparaginase, L-Glutaminase sowie weitere chemische und biologische Parameter an drei benachbarten Standorten untersucht: Standort I, reiner Fichtenaltbestand (Picea abies (L.) Karst ,110 Jahre); Standort II, Fichtenaltbestand mit Buchenunterbau (Fagus sylvatica , 5 Jahre); Standort III, reine Fichtenaufforstung (16 Jahre). Die Standorte II und III entstanden infolge des Waldumbaus aus reinen Fichtenaltbeständen. Die untersuchten Böden sind gekennzeichnet durch sehr niedrige pH-Werte (pH(H2O) 3, 7 , 4, 2, pH (CaCl2) 2, 9 , 3, 5), hohe Gesamtstickstoffgehalte (1, 06 , 1, 94,%), hohe metabolische Quotienten (6, 7,16, 9g CO2 kg,1 h,1), geringe Nmic -Gehalte (1, 1 , 3, 3,% des Gesamt-N, ausgenommen LOf1 von Standort III) und eine relativ hohe N-Nettomineralisation (175 , 1213 mg N Kg,1 in LOf1 und Of2, nach 4 Wochen Inkubation). Am Standort II nahm das C,:,N-Verhältnis und der qCO2 im LOf1 -Horizont deutlich ab, wohingegen der Gehalt an austauschbarem Ca sowie die Basensättigung im Mineralboden geringfügig zunahmen. Am Standort III nahm der N-Vorrat (Auflagehumus + Mineralboden 0 , 10,cm) um 30,% ab. In den LOf1 - und Of2 -Lagen des Auflagehumus dieses Standortes traten eine hohe N-Nettomineralisation (1, 5- bis 3fach höher als in den Standorten I und II), hohe Gehalte an mikrobiell gebundenem C und N, eine erhöhte Basalatmung sowie erhöhte qCO2 -Werte auf. In den Oh-Lagen hingegen nahm die Basensättigung ab. Alle untersuchten Standorte zeigten in der ersten Periode der Inkubation (0 bis 2 Wochen) eine geringe Netto-Nitrifikation. An den Standorten I und III fand in der späteren Periode (7. bis 11. Woche) eine Anreicherung an NO3 (20 , 100,% des gesamten mineralischen N-Vorrates) statt. Im Gegensatz dazu wurde am Standort II keine NO3 -N- Anreicherung festgestellt. Dies deutet auf einen Unterschied in der Zusammensetzung der mikrobiellen Gemeinschaften in den zwei verschiedenen Forstökosystemen hin. Nmic, N-Nettomineralisation, L-Asparaginase und L-Glutaminase korrelieren miteinander und zeigen eine enge Beziehung zu den Bewirtschaftungsformen. [source]

Herb layer changes (1954-2000) related to the conversion of coppice-with-standards forest and soil acidification

Lander Baeten
Abstract Question: Did the composition of the herb layer of a deciduous forest on loamy soils sensitive to soil acidification change between 1954 and 2000? How are these change related to the abandonment of traditional coppice-with-standards forest management and increased soil acidification? Location: Central Belgium (Europe). Methods: Twenty semi-permanent phytosociological quadrats from an ancient deciduous forest (Meerdaal forest) were carefully selected out of a total of 70 plots dating from 1954 and were revisited in 2000. Species composition and soil pH H2O were recorded using an analogous methodology. The studied period coincides with a period of forest conversion from coppice-with-standards towards a high forest structure and with an increase in acidifying and eutrophying deposition. Results: Between 1954 and 2000, species composition of the herb layer changed significantly. Redundancy analysis pointed to increased shade resulting from shifts in cover and species composition of the shrub and tree layer as the main driving force. Soil acidity increased and the majority of plots entered the aluminium buffer range, which potentially affected herb layer composition. Observations at the species level, especially a strong decrease in cover of the vernal species Anemone nemorosa supported this hypothesis. Conclusions: Our results show significant shifts in the forest herb layer in less than five decades. These shifts were related to an alteration in the traditional forest management regime and increased soil acidity. Whereas the effect of a changed management regime can be mitigated, soil acidification is less reversible. Testing the generality of these patterns on more extensive data sets is certainly needed. [source]

Comparative analysis of efficiency, environmental impact, and process economics for mature biomass refining scenarios

Mark Laser
Abstract Fourteen mature technology biomass refining scenarios , involving both biological and thermochemical processing with production of fuels, power, and/or animal feed protein , are compared with respect to process efficiency, environmental impact , including petroleum use, greenhouse gas (GHG) emissions, and water use,and economic profitability. The emissions analysis does not account for carbon sinks (e.g., soil carbon sequestration) or sources (e.g., forest conversion) resulting from land-use considerations. Sensitivity of the scenarios to fuel and electricity price, feedstock cost, and capital structure is also evaluated. The thermochemical scenario producing only power achieves a process efficiency of 49% (energy out as power as a percentage of feedstock energy in), 1359 kg CO2 equivalent avoided GHG emissions per Mg feedstock (current power mix basis) and a cost of $0.0575/kWh ($16/GJ), at a scale of 4535 dry Mg feedstock/day, 12% internal rate of return, 35% debt fraction, and 7% loan rate. Thermochemical scenarios producing fuels and power realize efficiencies between 55 and 64%, avoided GHG emissions between 1000 and 1179 kg/dry Mg, and costs between $0.36 and $0.57 per liter gasoline equivalent ($1.37 , $2.16 per gallon) at the same scale and financial structure. Scenarios involving biological production of ethanol with thermochemical production of fuels and/or power result in efficiencies ranging from 61 to 80%, avoided GHG emissions from 965 to 1,258 kg/dry Mg, and costs from $0.25 to $0.33 per liter gasoline equivalent ($0.96 to $1.24/gallon). Most of the biofuel scenarios offer comparable, if not lower, costs and much reduced GHG emissions (>90%) compared to petroleum-derived fuels. Scenarios producing biofuels result in GHG displacements that are comparable to those dedicated to power production (e.g., >825 kg CO2 equivalent/dry Mg biomass), especially when a future power mix less dependent upon fossil fuel is assumed. Scenarios integrating biological and thermochemical processing enable waste heat from the thermochemical process to power the biological process, resulting in higher overall process efficiencies than would otherwise be realized , efficiencies on par with petroleum-based fuels in several cases. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd [source]