Expansion Of Forest Cover Research Articles

Is Portugal’s forest transition going up in smoke?

The turnarounds from decrease to expansion in forest areas that took place during the last century have been examined through the lens of forest transition theory (FTT). Among temperate and Mediterranean European countries that have seen an expansion of forest cover, Portugal stands out as the only case in which this trend has recently been reverted. In this study, we explicitly map and document the forest transition (FT) in the country over the period 1907–2006, and investigate when and where forest transition happened de facto, and which were the land use transition pathways that resulted from the shrublands, agriculture, and forest interplay dynamics. After thematic and geometric harmonization of land cover maps from 1907, 1955, 1970, 1990, and 2006, a cluster analysis established four typologies, and a transition matrix was constructed to assess land cover dynamics. We found that up to 1955, FT occurred simultaneously with agricultural expansion, as shrubland areas diminished. Afterwards, with the retraction of agricultural area and the consequential decoupling of forest management from local actors, FT gained momentum and expanded up to the 1990s. While during the first half of the 20th century, forest expansion followed the “Scarcity” and “State Policy” pathways fostered by local socio-ecological feedback loops, throughout the second half of the century forest transition was driven by exogenous socio-economic forces, following “Economic Development” and “Globalization” pathways. We show how, despite these forces, FT can be derailed by endogenous factors such as wildfires, which limited and in some areas even reverted the afforestation process, initiating a deforestation phase. Since the necessary conditions for FT (technology shift, urbanization, agriculture retraction and public afforestation programs) were available in mainland Portugal, we advance the hypothesis that critical wildfire risk governance deficits may have been responsible for arresting FT. Considering the critical role of forests and other wooded areas in supporting climate change mitigation and sustainable development, our work provides useful evidence and insights for public decision makers on previously unaddressed dimensions of FTT.

Long-term change in drivers of forest cover expansion: an analysis for Switzerland (1850-2000)

The spatial distribution of forests in Europe represents the legacy of centuries of human land use decisions. Due to the limited availability of historical data, most studies on forest cover change focus only on analyzing recent decades, thereby overlooking the important long-term context. However, the latter is essential to improve our understanding of present landscape patterns. This study quantifies the spatiotemporal dynamics in drivers of forest gain in Switzerland. Specifically, we model forest gain in a long-term study covering 150 years (1850–2000) split into periods of similar length (∼30 years). This makes it possible to identify non-linear dynamics and whether drivers have changed over time. The rates of forest change are quantified based on analyzing historical maps and contemporary forest inventory data. Generalized additive models (GAMs) are fitted to examine the variation in the relative importance of socioeconomic and biophysical explanatory variables. Our results suggest that both biophysical and socioeconomic variables co-drive forest gain. Biophysical variables (such as temperature and slope) were identified as the major drivers explaining variations in forest gain. The most important socioeconomic driver was the change in the percentage of people employed per economic sector, although its effect came with a substantial time lag. Changes in employment per sector for the periods 1920–1941 and 1941–1980 were relevant for forest gain between 1980 and 2000. The identified time lag effect emphasizes the added value of long-term studies, since legacies may persist for decades, adding further complexity to contemporary land change processes. These findings are relevant to many temperate ecosystems that are experiencing increases in forest cover. Such insights can improve both future forest change predictions as well as the development of policies for sustainable landscape management.

Resilient landscapes in Mediterranean urban areas: Understanding factors influencing forest trends

Urban and peri-urban forests are recognized as basic elements for Nature-Based Solutions (NBS), as they preserve and may increase environmental quality in urbanized contexts. For this reason, the amount of forest land per inhabitant is a pivotal efficiency indicator to be considered in the sustainable governance, land management, planning and design of metropolitan areas. The present study illustrates a multivariate analysis of per-capita forest area (PFA) in mainland Attica, the urban region surrounding Athens, Greece. Attica is considered a typical case of Mediterranean urbanization where planning has not regulated urban expansion and successive waves of spontaneous growth have occurred over time. In such a context, an analysis of factors that can affect landscape changes in terms of PFA may inform effective strategies for the sustainable management of socio-ecological local systems in light of the NBS perspective. A total of 26 indicators were collected per decade at the municipal scale in the study area with the aim to identify the factors most closely associated to the amount of PFA. Indicators of urban morphology and functions have been considered together with environmental and topographical variables. In Attica, PFA showed a progressive decrease between 1960 and 2010. In particular, PFA progressively declined (1980, 1990) along fringe areas surrounding Athens and in peri-urban districts experiencing dispersed expansion of residential settlements. Distance from core cities and from the seacoast, typical urban functions (e.g., multiple use of buildings and per capita built-up area) and percentage of agricultural land-use in each municipality are the variables most associated with high PFA. In recent years, some municipalities have shown an expansion of forest cover, mainly due to land abandonment and forest recolonization. Findings from this case study have allowed us to identify priorities for NBS at metropolitan level aimed at promoting more sustainable urbanization. Distinctively, proposed NBS basically focus on (i) the effective protection of crop mosaics with relict woodlots; (ii) the improvement of functionality, quality and accessibility of new forests; and (iii) the establishment of new forests in rural municipalities.

Landscape changes, traditional ecological knowledge and future scenarios in the Alps: A holistic ecological approach.

In recent decades, a dramatic landscape change has occurred in the European alpine region: open areas have been naturally recolonized by forests as traditional agricultural and forest activities were reduced and reorganized. Land use changes (LUC) are generally measured through GIS and photo interpretation techniques, but despite many studies focused on this phenomenon and its effects on biodiversity and on the environment in general, there is a lack of information about the transformation of the human-environment connection. The study of Traditional Ecological Knowledge (TEK), such as the ability to recognize wild plants used as medicine or food, can suggest how this connection evolved through time and generations. This work investigates the relationship between the natural forest cover expansion that influences the loss of open areas and the loss of TEK. Different data sources and approaches were used to address the topic in all its complexity: a mix of questionnaire investigations, historical maps, GIS techniques and modelling were used to analyse past land use changes and predict future scenarios. The study area, Trentino, Italy, is paradigmatic of the alpine situation, and the land use change in the region is well documented by different studies, which were reviewed and compared in this paper. Our findings suggest that open area loss can be used as a good proxy to highlight the present state and to produce future scenarios of Traditional Ecological Knowledge. This could increase awareness of the loss of TEK in other Alpine regions, where data on TEK are lacking, but where environmental trends are comparable.

Legacies, socio-economic and biophysical processes and drivers: the case of future forest cover expansion in the Polish Carpathians and Swiss Alps

Mountain forest areas are key for providing a wide range of ecosystem services and are hot spots for land use change processes, in particular, increase in forest cover at the expense of mountain pastures and meadows. Mountain forest systems in eastern and western Europe have likely similar future socio-economic situations but significantly different socio-economic history. Using a scenario-based land use modelling approach (Dyna-CLUE framework) we model three scenarios (trend, liberalisation and self-sufficiency) of future land use in the Polish Carpathians and the Swiss Alps, focussing on forest cover change. We find that forest cover increase can be expected to continue in European mountainous regions under all likely scenarios, limited only by relatively strict policy interventions. Biophysical factors, rather than socio-economic ones, are key for defining the suitability for, and therefore likely locations of future forest cover, but land use legacy plays a very important role in the spatial patterns of future forest cover, particularly in eastern Europe.

Late Quaternary climate variability and vegetation response in Ziro Lake Basin, Eastern Himalaya: A multiproxy approach

Pollen, phytolith and stable carbon isotopic records provide new insights into the palaeoenvironmental and palaeoclimatic changes in Ziro Lake Basin, sub-Himalayan Arunachal Pradesh, India since pre-LGM time. Phytoliths record a minor change in grass/woodland cover and appear to be more sensitive than pollen grains to climate fluctuations. Both pollen and non-pollen palynomorph data suggest prevalence of a dense C3 species-dominated moist semi-evergreen forest in the area until the LGM which shows conformity with δ13C data. The phytolith assemblage indicates an alteration in forest cover with expansion of C4 grasses during the LGM. The study further indicates a climatic amelioration with intensification of south-west monsoon during 10.2–3.8 ka and an expansion of forest cover. After 3.8 ka there was a rising trend of dryness, shrinkage in forest cover, and a slight increase in C4 species while C3 plants dominated. Ecosystem variability also points towards a hydrological transformation in the area since pre-LGM time. Application of coexistence approach on pollen data reveals that prior to the LGM the mean annual temperature and mean annual precipitation were approximately 19.3 ± 0.001 °C and 1925 ± 15 mm respectively. Between 10.2 and 3.8 ka MAT was about 19.4 ± 0.5 °C, while MAP was 1901 ± 41.3 mm. Between 3.8 and 1.2 ka and onwards a slight increase in MAT (∼0.3C°) was observed with further decrease in MAP to 1861 ± 33.4 mm. During pre and post LGM times, MAT was more or less similar in the Ziro Lake Basin which increased gradually after 3.8 ka and was ∼1.2 C° higher than today. Prior to the LGM, MAP was higher than the present day by 94 mm, between 10.2 and 3.8 ka by 70 mm and since 3.8 ka onwards by ∼30 mm showing a tendency of gradual decline suggesting a consequent increase in dryness.

Evaluating forest policy implementation effectiveness with a cross-scale remote sensing analysis in a priority conservation area of Southwest China

China's Natural Forest Protection Program (NFPP) and Sloping Land Conversion Program (SLCP), introduced in 1998 and 1999, respectively, are integral parts of the world's largest reforestation effort. State-reported forest cover data indicate effective policy implementation through net forest cover expansion but overlook the scale-dependence of and spatial variation in forest cover change patterns and also lack reliable data on small-scale and illegal logging. As a result, there is considerable uncertainty over the spatial distribution of forest cover change and ultimately the policies' effectiveness at increasing forest cover. This research uses Landsat Thematic Mapper imagery-derived multitemporal Tasseled Cap variables and a decision tree classifier to map short- and long-term forest cover change across three administrative levels in the priority conservation area of Diqing Tibetan Autonomous Prefecture in Yunnan Province. Results indicate a 73% reduction in the rate of forest cover loss and a more than doubled rate of forest cover gain from 1990–1999 to 1999–2009 across the prefecture, both of which support a positive assessment of policy implementation. However, prefectural results are countered by spatially disparate forest cover gain and loss trends at the county- and township-level in the decade following the policies' introductions. Further, more than half of Diqing's townships, mainly those in the prefecture's south where tourism has been rapidly developing, saw continued net forest cover loss attributable to small-scale timber harvesting for tourism-driven construction. This research thus exposes cross-scale spatially disparate forest cover change indicative of highly differentiated policy implementation effectiveness, and shows the pattern by which regional development has redirected, rather than reduced, forest cover loss, contrary to the goals of the NFPP and SLCP.

Uso do produto MOD13Q1 do sensor Modis para análise temporal e mapeamento das florestas nas Serras do Sudeste e Campanha Meridional do Rio Grande do Sul

Imagens NDVI (Índice de Vegetação por Diferença Normalizada) do sensor Modis foram utilizadas para mapear as classes de uso e cobertura da terra nas Serras do Sudeste e Campanha Meridional do Rio Grande do Sul. A metodologia compreendeu a elaboração de um banco de dados espaciais e a aplicação de técnicas de processamento digital (contraste linear, classificação digital e operações aritméticas) sobre imagens dos satélites Landsat e Terra de diversas datas. Os resultados indicaram que a cobertura florestal passou de 8,6% para 11,6% e 14,3% da área total da microrregião Serras do Sudeste, entre os anos 2000, 2004 e 2008. Na Campanha Meridional, a expansão da cobertura florestal passou de 11,1% para 11,2% e 11,5% da área total no mesmo período. Conclui-se que imagens MOD13Q1, de baixa resolução espacial (250 m), podem ser usadas em grandes áreas para mapear florestas e os demais temas adequadamente.

Geographical genetic structuring and phenotypic variation in the Vellozia hirsuta (Velloziaceae) ochlospecies complex

Vellozia hirsuta forms a complex presenting wide morphological and anatomical variation, resulting in five specific names and 14 morpho-anatomical patterns occurring in disjunct populations. We carried out a phylogeographical study to investigate the existence of correlation among the genetic and morphological patterns within this complex, and to determine whether it is composed of various species or should be treated as an ochlospecies, a species having widely polymorphic and weakly polytypic complex variation, with morphological characteristics varying independently. We carried out phylogeographical analyses using cpDNA rpl32F-trnL intergenic region. We found 20 haplotypes in 23 populations sampled. The populations are genetically structured (Φ(ST) = 0.818) into four phylogeographical groups demonstrating geographical structuring but with no correlation with morpho-anatomical patterns. Our analyses do not support recognizing any of the species now synonymized under Vellozia hirsuta. The northern populations were the most genetically differentiated and could be considered a distinct taxon, as they are also morphologically different. It is recommended that Vellozia hirsuta be considered a single enormously variable species. The patterns of variation within V. hirsuta probably are related to climatic changes that occurred during the Pleistocene Epoch in tropical Brazil when reductions in forest cover favored the expansion of V. hirsuta populations into extensive lowland areas. The expansion of forest cover at the end of the glaciations would have again restricted the occurrence of campos rupestres vegetation to high elevations, which constitute the current centers of diversity of this species.

Late postglacial paleoenvironmental change in the northeastern Mediterranean region: Combined palynological and molecular biomarker evidence

Three gravity cores collected from the NE Mediterranean (NEMR) across a transect from the northern Aegean Sea (North Skyros basin) to the south Cretan margin (SCM), were investigated for pollen and terrestrial biomarkers derived from epicuticular waxes of vascular plants during the last ∼20 ky. Pollen data show diversified mixed temperate forest in the northern borderlands and enhanced Mediterranean vegetation in the southern areas, documenting an N–S climatic trend. Terrestrial plant biomarkers and their diagnostic geochemical indices exhibit latitudinal patterns which are interpreted in terms of the different delivery pathways (fluvial/runoff vs. atmospheric transport), resulting from the climate conditions during different periods. During the Late Glacial and early deglaciation periods (20–14 ka BP) relatively increased humidity (H-index) is recorded in the north Aegean Sea, while in the South drier climate was the limiting factor for vegetation development. During this interval, terrestrial n-alkanes showed increased accumulation rates, suggesting massive transport of terrestrial organic matter through runoffs and rivers, followed by weaker input after 14 ka BP. After ∼11 ka BP a major expansion of forest cover is evidenced in the NEMR, accompanied by a higher H-index because of the climatic amelioration. The forest vegetation exhibited regionally different characteristics, with cool temperate taxa being more abundant in the Aegean cores, while the SCM record is being featured by Mediterranean elements. At the onset of the Holocene and throughout the Holocene Climatic Optimum the delivery of terrestrial biomarkers increased and became more significant in the Aegean sites compared to the SCM site. Within the Holocene, the average chain length (ACL) of long chain n-alkanes exhibits lower values in the northern Aegean than in the southeastern Aegean and SCM, indicating the predominance of warmer species southwards. Finally, the H-index records a conspicuous humidity increase between 5.4 and 4.3 ka BP in the south Aegean that coincides with an increase in the terrestrial biomarker supply and the deposition of a distinct sapropel-like layer, SMH (Sapropel Mid Holocene). Similar trends in T (temperature) and H indices are slightly delayed and attenuated in the northern Aegean and are accompanied by an increase in the ACL index. A noticeable increase in the accumulation rates (ARs) of terrestrial biomarkers and the HPA index values during this period are clearly recorded in all three cores, indicative of enhanced terrigenous inputs of organic matter along with higher in-situ preservation.

Land-cover changes and recent hydrological evolution in the Duero Basin (Spain)

Land-use and land-cover changes have attracted substantial scientific interest in recent years because of their marked influence on hydrological cycles. In developed countries of the Mediterranean basin, the generalized revegetation and forest growth in mountainous areas that occurred during the last five decades are negatively affecting the evolution of water resources in headwaters. In this study, changes in land cover in the Duero River Basin (northern Spain) during the last 50 years were analyzed and their role in hydrological evolution was estimated. For this purpose, step-wise linear regressions were developed to estimate the evolution of runoff as a function of climate (precipitation and temperatures). The results show a significant expansion of forest cover in the headwaters, although it has been more extensive in the mountains to the north of the basin than to the south. River discharges in the headwaters underwent a generalized decline during the study period (1961–2006), but precipitation over the same period did not show an appreciable trend. In the absence of noticeable trends in removal of water for human consumption, our results indicate that revegetation is contributing to the observed hydrological decline. Our hypothesis is confirmed because of the greater divergence in the evolution of precipitation and runoff in the northern headwaters (more forest growth) than in the south headwaters (less forest growth). Results suggest that further increases in forest area will enhance hydrological decline and highlight the importance of integrating land-cover information in water availability assessments in a region where water is a strategic resource.

Streamflow response to headwater reforestation in the Ganaraska River basin, southern Ontario, Canada

AbstractIncreased attention is being paid to the role of reforestation in strategies for sustainable forest management, landscape restoration and carbon sequestration. Reforestation of drainage basins is generally assumed to reduce annual streamflow as well as peak and low flows. However, most studies of reforestation effects on streamflow have been conducted on small experimental basins, and the applicability of their results to larger basins is unclear. This study revisits an earlier examination of streamflow response to headwater reforestation in a 267 km2 basin (Ganaraska River) in southern Ontario, Canada for 1945–2007. Forest cover in the basin headwaters increased from 13 km2 in 1945 to 31 km2 by 1990, with most of this change between 1950 and 1965. Streamflow metrics from the reforested basin and two headwater sub‐basins were compared to those from a nearby basin and sub‐basin of similar size and physiography to the Ganaraska basins but without extensive headwater reforestation. No temporal trends were found for inter‐basin differences in annual runoff or runoff ratios for the entire Ganaraska basin or its largest sub‐basin; however, reforestation appears to have reduced several metrics of peak streamflow at the basin and sub‐basin scale. Relationships between high flows classified according to generating event type and the associated precipitation depth suggest that expansion of forest cover in the Ganaraska River basin (GRB) and associated changes in microclimatic conditions have reduced the potential for frozen soil to generate surface runoff and high flows in response to rain‐on‐snow during spring snowmelt. This was accompanied by increased low flows from the GRB and its sub‐basins from 1960 to 2007 relative to the control basin, suggesting that the expanded forest cover has enhanced groundwater recharge by prolonging spring snowmelt and promoting infiltration of rainfall and snowmelt inputs relative to non‐forested areas. Some discrepancies between these results and those of other studies of streamflow response to reforestation may be attributed to the relatively large size of the GRB and the limited extent of reforestation. Nevertheless, the results highlight the importance of considering how reforestation may affect key hydrologic processes in a given landscape when predicting the resulting streamflow response. Copyright © 2011 John Wiley & Sons, Ltd.

90 years of forest cover change in an urbanizing watershed: spatial and temporal dynamics

Landscape structure in the Eastern US experienced great changes in the last century with the expansion of forest cover into abandoned agricultural land and the clearing of secondary forest cover for urban development. In this paper, the spatial and temporal patterns of forest cover from 1914 to 2004 in the Gwynns Falls watershed in Baltimore, Maryland were quantified from historic maps and aerial photographs. Using a database of forest patches from six times—1914, 1938, 1957, 1971, 1999, and 2004—we found that forest cover changed, both temporally and spatially. While total forest area remained essentially constant, turnover in forest cover was very substantial. Less than 20% of initial forest cover remained unchanged. Forest cover became increasingly fragmented as the number, size, shape, and spatial distribution of forest patches within the watershed changed greatly. Forest patch change was also analyzed within 3-km distance bands extending from the urban core to the more suburban end of the watershed. This analysis showed that, over time, the location of high rates of forest cover change shifted from urban to suburban bands which coincides with the spatial shift of urbanization. Forest cover tended to be more stable in and near the urban center, whereas forest cover changed more in areas where urbanization was still in process. These results may have critical implications for the ecological functioning of forest patches and underscore the need to integrate multi-temporal data layers to investigate the spatial pattern of forest cover and the temporal variations of that spatial pattern.

The geoarchaeological and paleoenvironmental context of Paleoindian sites in western Middle Park, Colorado, USA

AbstractGeoarchaeological investigations in western Middle Park provide important information for understanding the soil‐stratigraphic context of Paleoindian components, as well as the latest Quaternary environmental change and landscape evolution in a Southern Rocky Mountain intermontane basin. Paleoindian components are associated with the oldest two of four latest Quaternary stratigraphic units (1–4) recognized in co‐alluvial mantles (combined slopewash and colluvium) in uplands and in alluvial valley fills. Limited data suggest accumulation of unit 1 as early as ∼12,500 14C yr B.P. in alluvial valleys and by at least ∼11,000 14C yr B.P. in uplands was followed by brief stability and soil formation. A relatively widespread disconformity marks earliest Holocene erosion and substantial removal of latest Pleistocene deposits in upland and alluvial settings followed by unit 2 deposition ∼10,000–9000 14C yr B.P., perhaps signaling the abrupt onset of an intensified summer monsoon. In situ Paleoindian components in uplands are found in a moderately developed buried soil (the Kremmling soil) formed in units 1 and 2 in thin (≤1m) hillslope co‐alluvial mantles. The Kremmling soil reflects geomorphic stability in upland and alluvial settings ∼9000–4500 14C yr BP, and represents a buried landscape with the potential to contain additional Paleoindian components, although elsewhere in western Middle Park Early Archaic components are documented in morphologically similar soils. Kremmling soil morphology, the relative abundance of charcoal in unit 2 relative to younger units, and charcoal morphology indicate the expansion of forest cover, including Pinus, and grass cover during the early and middle Holocene, suggesting conditions moister than present. © 2010 Wiley Periodicals, Inc.

From the Holocene to the Anthropocene: A historical framework for land cover change in southwestern South America in the past 15,000 years

The main forest transitions that took place in south-central Chile from the end of the last glaciation to the present are reviewed here with the aim of identifying the main climatic and socio-economic drivers of land cover change. The first great transition, driven primarily by global warming, is the postglacial expansion of forests, with human populations from about 15,000 cal. yr. BP, restricted to coastlines and river basins and localized impact of forest fire. Charcoal evidence of fire increased in south-central Chile and in global records from about 12,000 to 6000 cal. yr. BP, which could be attributed at least partly to people. The subsequent expansion of agriculture led to much clearing of forests and the spread of weeds and other indicators of open habitats. The Spanish colonial period in America may have been followed by a transient expansion of forest cover into abandoned land, as indigenous population declined rapidly due to disease and slaughter. The 18th and 19th centuries brought about extensive loss of forests due to the massive impact of lumber extraction for mining operations both in central Chile and in western North America. Two centuries of intensive deforestation, coupled to grazing by cattle and extremely variable rainfall had long-lasting effects on forest cover in south-central Chile, which persist until today. The transition from a preindustrial to an industrial society brought about the “golden age” of timber harvest, assisted by mobile sawmills and railway transportation since the late 1800s. These advances led to the exhaustion of native commercial timber by the late 20th century in south-central Chile. In North America, harvestable stands were exhausted in New England and the Midwest around 1920. Settlement of the independent territories in the late 1800s and early 1900s implied vast burning and clearing of land and mounting soil erosion. Industrial forestry, based on government-subsidized massive plantations of short-rotation exotic trees, developed in the late 20th century, in connection with postindustrial displacement of exploitative activities from developed to third-world nations. In the last two decades, economic globalization and free trade promoted the expansion of new crops and further decline of woodlands, despite modest increases in forest cover. These patterns are repeated in many Latin American countries. To prevent further depletion of native forest resources and to provide an insurance against climate change, in the 21st century developing nations should aim at: (1) relocating subsidies from fiber farms to restoring diverse forest cover, (2) promoting ecosystem management of diverse forest and crops within landscapes, and (3) fostering diverse cultural relationships between people and their land.

Contrasting impacts of Dansgaard–Oeschger events over a western European latitudinal transect modulated by orbital parameters

Terrestrial and marine proxies (pollen, planktic and benthic foraminiferal oxygen isotopes, alkenone- and foraminifer-derived sea-surface temperatures (SSTs), ice-rafted debris) from IMAGES deep-sea cores MD95-2042 and SU81-18 (37°N, 10°W), MD99-2331 and MD03-2697 (42°N, 9°W), and MD04-2845 (45°N, 5°W) show that western European and offshore environments were strongly affected by Dansgaard–Oeschger (D–O) and Heinrich (H) events. We concentrate here on latitudinal variability in the forest cover extent and composition of western Europe during the succession of D–O events, showing new pollen records for core MD04-2845 and for marine isotopic stages (MIS) 3 and 4 of core MD99-2331. In general, cold SSTs characteristic of Greenland stadials were contemporaneous with the expansion of semi-desert or steppic vegetation while Greenland interstadials were synchronous with the expansion of forest. Our data reveal that the amplitude of Atlantic and Mediterranean forest expansions differs for any given D–O warming during the glacial period (74–18 ka). In the western Mediterranean, D–O 16–17 and D–O 8 and 7 (corresponding to minima in precession) were associated with strong expansion of forest cover contrasting with weak expansion of forest cover during D–O 14 and 12; the opposite pattern is revealed at the Atlantic sites. Further north, the strongest Greenland warmings are recorded for D–O 19, 11 and 8. This contrasting latitudinal climatic scenario is compared with other northern hemisphere records, revealing similarities between the Mediterranean climate and the Asian monsoon regime, which may relate to a summer atmospheric teleconnection between the two regions comparable to the present-day situation. Parallels between Mediterranean climate enhancement and peaks in global methane (CH 4) during the last glacial period suggest a significant role of monsoon activity in determining CH 4 emission from wetlands.

Modelling Regional Climate Change Effects On Potential Natural Ecosystems in Sweden

This study aims to demonstrate the potential of a process-based regional ecosystem model, LPJ-GUESS, driven by climate scenarios generated by a regional climate model system (RCM) to generate predictions useful for assessing effects of climatic and CO2 change on the key ecosystem services of carbon uptake and storage. Scenarios compatible with the A2 and B2 greenhouse gas emission scenarios of the Special Report on Emission Scenarios (SRES) and with boundary conditions from two general circulation models (GCMs) – HadAM3H and ECHAM4/OPYC3 – were used in simulations to explore changes in tree species distributions, vegetation structure, productivity and ecosystem carbon stocks for the late 21st Century, thus accommodating a proportion of the GCM-based and emissions-based uncertainty in future climate development. The simulations represented in this study were of the potential natural vegetation ignoring direct anthropogenic effects. Results suggest that shifts in climatic zones may lead to changes in species distribution and community composition among seven major tree species of natural Swedish forests. All four climate scenarios were associated with an extension of the boreal forest treeline with respect to altitude and latitude. In the boreal and boreo-nemoral zones, the dominance of Norway spruce and to a lesser extent Scots pine was reduced in favour of deciduous broadleaved tree species. The model also predicted substantial increases in vegetation net primary productivity (NPP), especially in central Sweden. Expansion of forest cover and increased local biomass enhanced the net carbon sink over central and northern Sweden, despite increased carbon release through decomposition processes in the soil. In southern Sweden, reduced growing season soil moisture levels counterbalanced the positive effects of a longer growing season and increased carbon supply on NPP, with the result that many areas were converted from a sink to a source of carbon by the late 21st century. The economy-oriented A2 emission scenario would lead to higher NPP and stronger carbon sinks according to the simulations than the environment-oriented B2 scenario.

Edge Effect on Acorn Removal and Oak Seedling Survival in Mexican Lower Montane Forest Fragments

Vegetation structure of forest edges and type of adjacent field can affect seed and seedling survival patterns of tree species. We investigated acorn removal and seedling survival of Quercus germana and Q. xalapensis in relation to woody plant density across old field-forest gradients with soft and abrupt edges. Experiments were established along four parallel bands located at 40–50 m in the forest, forest and field edges (0–10 m to each side of the border), and 20–30 m in the old field. Within each band, woody plant and acorn density was measured, and four points for acorn and seedling removal experiments were randomly positioned. In each position, 20 acorns or four seedlings were placed. Survival was monitored during one month. In abrupt edges, acorn density was higher along edges than in forest interior. Also, higher acorn removal and seedling mortality were observed in the adjacent old-field whereas acorn and seedling survival was the highest at the edges. Acorn and seedling survival was positively correlated to woody vegetation density. As the vegetation density of field and forest edges grows, abrupt edges develop into soft edges, and they become more hospitable to oak recruitment and then to forest cover expansion.

Reckoning social forestry in Bangladesh: policy and plan versus implementation

The history of scientific forest management in Bangladesh dates back to the nineteenth century with defined forest policies and laws. Due to various socio-economic and socio-political factors, forest cover of the countryreduced drastically and all such policy initiatives proved ineffective. Although traditional forest management objectives covered a wide range from economic benefit to ecological stability, these have never been attained fully. Huge population and limited land area compelled policy makers to think about alternatives to traditional forest management. One alternative, social forestry, was introduced in Bangladesh in early 1980s and has proved to be extremely successful. While traditional forest management resulted in a net loss of forest resource cover, social forestry on the other hand, is playing a vital role in the expansion of forest cover (40387 ha of new forest cover and 48420 km new strip plantation since the mid-1980s) benefiting thousands of poor people. Results show that during the last four years (2000-2003) more than 23 000 individuals benefited from the final felling of different social forestry plantations (woodlot, agroforestry and strip plantation). This generated a total income of US$ 5.6 million for the government and US$ 5.3 million for participants plus US$ 1.2 million for the Tree Farming Fund - a 10 per cent depository reserve to sustain the practice in the long run. Although average individual final returns (US$ 223 person - 1 ) are not so attractive, some people got about US$ 5000 to US$ 8500 from final felling, sufficient to improve their standard of living and social position. Despite the success so far achieved, social forestry in Bangladesh still suffers from various institutional deficiencies like organization, skilled manpower, legitimate usufruct rights, peoples' participation from policy to implementation and clear budgetary arrangements. Besides, until now the role of relevant actors is not well defined in all the steps of social forestry practice in Bangladesh. Unless the participants are given clear legitimate usufruct rights, they will remain sceptical towards this programme. They should have good and meaningful access from planning to implementation. In the context of institutional development, there are governmental policy guidelines and a 20-year Master Plan for Bangladesh. Although some steps have been partially completed, there is still much to do to comply with forest policy guidelines and the Master Plan. It is shown that in the last seven years (1995/96-200½002) only US$ 15.41 million a - 1 has actually been spent against an allocated sum of US$ 68.37 million a - 1 . Therefore, if the intention is to institutionalize social forestry in Bangladesh, government and policy makers should actively come forward. Otherwise the full potential of social forestry in Bangladesh will not become a reality.

Paleoindian environmental change and landscape response in Barger Gulch, Middle Park, Colorado

AbstractMiddle Park, a high‐altitude basin in the Southern Rocky Mountains of north‐central Colorado, contains at least 59 known Paleoindian localities. At Barger Gulch Locality B, an extensive Folsom assemblage (˜10,500 14C yr B.P.) occurs within a buried soil. Radiocarbon ages of charcoal and soil organic matter, as well as stratigraphic positions of artifacts, indicate the soil is a composite of a truncated, latest‐Pleistocene soil and a younger mollic epipedon formed between ˜6000 and 5200 14C yr B.P. and partially welded onto the older soil following erosion and truncation. Radiocarbon ages from an alluvial terrace adjacent to the excavation area indicate that erosion followed by aggradation occurred between ˜10,200 and 9700 14C yr B.P., and that the erosion is likely related to truncation of the latest‐Pleistocene soil. Erosion along the main axis of Barger Gulch occurring between ˜10,000 and 9700 14C yr B.P. was followed by rapid aggradation between ˜9700 and 9550 14C yr B.P., which, along with the erosion at Locality B, coincides with the abrupt onset of monsoonal precipitation following cooling in the region ˜11,000–10,000 14C yr B.P. during the Younger Dryas oscillation. Buried soils dated between ˜9500 and 8000 14C yr B.P. indicate relative landscape stability and soil formation throughout Middle Park. Morphological characteristics displayed by early Holocene soils suggest pedogenesis under parkland vegetation in areas currently characterized by sagebrush steppe. The expansion of forest cover into lower elevations during the early Holocene may have resulted in lower productivity in regards to mammalian fauna, and may partly explain the abundance of early Paleoindian sites (˜11,000–10,000 14C yr B.P., 76%) relative to late Paleoindian sites (˜10,000–8000 14C yr B.P., 24%) documented in Middle Park. © 2005 Wiley Periodicals, Inc.