Changes In Tree Species Composition Research Articles

Afforestation and changes in forest composition affect runoff in large river basins with pluvial regime and Mediterranean climate, Chile

• We study the water response related with forest plantation expansion in large basins. • Annual runoff decreases with afforestation affecting over 16% of total catchment area. • Summer runoff decreases due to afforestation should be carefully interpreted. Chile has developed an important economy based on some 2.6 million hectares of planted forests which have been questioned because of their impact on water resources. This report analyses the water response associated with forest plantation expansion and changes in tree species composition in six large river basins (from 94 to 1545 km 2 ) of pluvial regime located between 37°30′ and 39°S in central-southern Chile, an area characterized by a Mediterranean climate. Long term discharge and precipitation records were obtained from national data bases and land uses for different time periods were generated using satellite images and digital maps. Annual water reductions were detected in three river basins where net increases in forested area affected more than the 16% of total catchment area. In the same basins and between the same periods reductions of summer runoff were also noticed although these decreases should be carefully considered as summer runoff also decreased in basins where no significant land use changes occurred. The analysis of the daily flow duration curves indicates that the highest effects occur for Q 50% (daily discharge exceeded 50% of time) while Q 80% , Q 85% and Q 90% are much less affected. Although forest plantation expansion and changes in tree species composition have the potential to reduce streamflow, since Q 80% and Q 90% are used to define permanent and continuous Water Rights according to the Chilean Water Code, it is possible that already existing permanent and continuous water rights could be only marginally affected by the increase of the planted area. The results presented in this document can be used to support discussions related to the development of water allocation regulations among competing economic water users.

Compositional shifts in Costa Rican forests due to climate‐driven species migrations

Species are predicted to shift their distributions upslope or poleward in response to global warming. This prediction is supported by a growing number of studies documenting species migrations in temperate systems but remains poorly tested for tropical species, and especially for tropical plant species. We analyzed changes in tree species composition in a network of 10 annually censused 1-ha plots spanning an altitudinal gradient of 70-2800m elevation in Costa Rica. Specifically, we combined plot data with herbarium records (accessed through GBIF) to test if the plots' community temperature scores (CTS, average thermal mean of constituent species weighted by basal area) have increased over the past decade as is predicted by climate-driven species migrations. In addition, we quantified the contributions of stem growth, recruitment, and mortality to the observed patterns. Supporting our a priori hypothesis of upward species migrations, we found that there have been consistent directional shifts in the composition of the plots, such that the relative abundance of lowland species, and hence CTS, increased in 90% of plots. The rate of the observed compositional shifts corresponds to a mean thermal migration rate (TMR) of 0.0065°Cyr(-1) (95% CI=0.0005-0.0132°Cyr(-1) ). While the overall TMR is slower than predicted based on concurrent regional warming of 0.0167°Cyr(-1) , migrations were on pace with warming in 4 of the 10 plots. The observed shifts in composition were driven primarily by mortality events (i.e., the disproportionate death of highland vs. lowland species), suggesting that individuals of many tropical tree species will not be able to tolerate future warming and thus their persistence in the face of climate change will depend on successful migrations. Unfortunately, in Costa Rica and elsewhere, land area inevitably decreases at higher elevations; hence, even species that are able to migrate successfully will face heightened risks of extinction.

A comparison of fungal endophytic community diversity in tree leaves of rural and urban temperate forests of Kanto district, eastern Japan

To clarify the effects of forest fragmentation and a change in tree species composition following urbanization on endophytic fungal communities, we isolated fungal endophytes from the foliage of nine tree species in suburban (Kashiwa City, Chiba) and rural (Mt. Wagakuni, Ibaraki; Mt. Takao, Tokyo) forests and compared the fungal communities between sites and host tree species. Host specificity was evaluated using the index of host specificity (Si), and the number of isolated species, total isolation frequency, and the diversity index were calculated. From just one to several host-specific species were recognized in all host tree species at all sites. The total isolation frequency of all fungal species on Quercus myrsinaefolia, Quercus serrata, and Chamaecyparis obtusa and the total isolation frequency of host-specific species on Q. myrsinaefolia, Q. serrata, and Eurya japonica were significantly lower in Kashiwa than in the rural forests. The similarity indices (nonmetric multidimensional scaling (NMS) and CMH) of endophytic communities among different tree species were higher in Kashiwa, as many tree species shared the same fungal species in the suburban forest. Endophytic fungi with a broad host range were grouped into four clusters suggesting their preference for conifer/broadleaves and evergreen/deciduous trees. Forest fragmentation and isolation by urbanization have been shown to cause the decline of host-specific fungal species and a decrease in β diversity of endophytic communities, i.e., endophytic communities associated with tree leaves in suburban forests were found to be depauperate.

Carbon turnover in mixed stands: Modelling possible shifts under climate change

Adaptation of forest management to changing climate may lead to remarkable changes in tree species composition. Deciduous species are predicted to be favoured in a warmer climate, but the competitive capacity of different tree species requires detailed analysis. The main objectives of this study were to assess how varied initial proportions of tree species affected productivity in mixed stands, and to evaluate the biomass production and carbon sequestration potential of trees and soil in mixed stands in a changing climate. We used the individual-based simulation model EFIMOD combined with the model of soil organic matter dynamics ROMUL to simulate spatially explicit competition between trees for light and nutrients. We focused our simulations on the most common type of site (mesic site, Myrtillus type) in southern Finland. The average carbon and nitrogen pools in the forest floor and mineral soil were used as initial soil data. The ambient climate scenario was based on measured data (1961–2007) from the Finnish Meteorological Institute. Climate change scenarios were based on runs of three general circulation models. We simulated the forest stand dynamics of two- and three-species mixtures (Silver birch, Scots pine and Norway spruce) with different initial proportions. In mixed spruce–birch stands, spruce replaced birch whatever the initial density, regardless of climatic scenario. In the beginning of the development of mixed spruce–pine stands, pine grew faster and increased its proportion of biomass by 10–20%. In pine–birch stands, the dominant species maintained its dominating position, but the proportion of pine generally declined by the end of simulation in birch-dominated stands. In mixed stands of three tree species, spruce tended to dominate by the end of a 100-year simulation period, independently of the initial proportions. The highest average carbon stock in standing biomass was observed in mixed stands with three species and in spruce-dominated stands. Climate change increased stand productivity and the increase in coniferous stands was more remarkable than in birch-dominated stands. In addition, soil was affected by species composition: increased proportions of pine resulted in increasing carbon stocks in the forest floor. Climate change negatively affected accumulation of organic matter in soil, especially in the spruce-dominated stands.

Certified and Uncertified Logging Concessions Compared in Gabon: Changes in Stand Structure, Tree Species, and Biomass

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 >10cm 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 2-3months after the 508ha FSC study area and the 200ha CL study area were selectively logged at respective intensities of 5.7m(3)/ha (0.39 trees/ha) and 11.4m(3)/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.

Physico-chemical and functional characteristics of soil charcoal produced at five different temperatures

The intensity of boreal forest wildfires is highly variable, such that natural wood charcoal can be produced at different peak temperatures. This, in turn, may have consequences on the physico-chemical and functional properties of the charcoal that is returned to soil. We report on a microcosm study where black spruce wood charcoal produced at five peak temperatures (450, 550, 650, 750 and 850 °C) was added to forest soils, and subsequently incubated at room temperature, with and without additions of condensed tannins and/or protein. A fourth experimental factor was added to this full factorial design, which comprised the mixing of soil so as to simulate mechanical scarification in the field. Increasing the charcoal production temperature resulted in higher %C and lower %O and %H, suggesting an increase in aromatic structures. Specific surface area was negligible at 450 °C, was about 50 m2 g−1 at 550 °C, and was 260–300 m2 g−1 at the three highest temperatures. At these higher charcoal production temperatures, 85–90 % of total surface area was attributed to pores <20 nm. The incubation demonstrated a decline in soil basal respiration (BR) with charcoal addition, with increasing charcoal production temperature and with tannin additions, whereas BR increased with protein addition and with soil mixing. Charcoal addition reduced soil microbial biomass (MB), however charcoal production temperature had no effect on MB. Consequently, we observed a decrease in microbial metabolic quotient (qCO2) with increasing charcoal production temperature, which reflected the decline in BR. Increasing charcoal production temperature increased net NH4+ production in the non-mixed soils, but decreased net NH4+ production in the mixed soils. Protein additions increased net NH4+ production more so in the mixed than in the non-mixed soils. Our results thus show that charcoal production temperature has a marked and significant effect on soil C and N cycling, and that these effects are substantially modified by soil mixing. This further suggests that changes in boreal forest fire intensity, due to anthropogenic changes in tree species composition or climate, could affect the dynamics of forest regeneration through variations in the chemical and functional properties of the charcoal, and that these effects may be substantially modified by post-fire silvicultural treatments such as mechanical scarification.

Changes in tree species composition in Mediterranean mountains under climate change: Indicators for conservation planning

Since the last glacial–interglacial cycles, Mediterranean mountains in Southern Europe have constituted the southern refuge of numerous species of Eurosiberian and Boreal origin. Some vestiges of European Tertiary flora have also remained in this area. These mountains present one of the continent's highest plant diversity indices deriving from their geographic and historical circumstances throughout the Quaternary. Throughout this century, a change in the biogeographic characteristics of these mountains is to be expected as a result of climate change.Based on four Intergovernmental Panel on Climate Change (IPCC) scenarios, we developed a multivariate analysis model for mountain ranges in Central Spain (Southern Europe), enabling us to adjust data on vegetation, climate, lithology and availability of soil water. With high-resolution data on species occurrences and abiotic characteristics for better accounting of micro-refugia and topographic complexity in mountain regions, we assess the future potential distribution of tree species and changes in plant communities under climate change. Our model provides the climate descriptors that most influence changes in species distribution and which lead us to consider the parameters of these changes as indicators for management.We project for this century a significant spread of Mediterranean tree communities in detriment to temperate or cold-adapted tree communities. In mountain forests in northern Europe, limitations on plant growth are mainly thermic, and the boreal and subalpine species in high- and mid-mountain regions are therefore the ones most threatened by the predicted global warming. To the contrary, our results show that in mountains in southern Europe, the formations that will undergo the greatest changes will be at piedmonts and low-mountain levels, due to increased hydric deficit. These results suggest that nature conservation strategies currently call for new approaches that take into account the fact that climate change is a driving force of species distribution. The results can be used at the landscape scale for management of forest species and for the design of protected areas.

Terrestrial herpetofaunal assemblages in secondary forests and exotic Lophostemon confertus plantations in South China

Deforestation is one of the major causes of biodiversity loss. Globally, large areas of primary forest have been replaced by secondary forests and plantations, and changes in tree species composition have often led to alteration of plant and animal communities that were associated with those primary forests. Hong Kong has experienced a long history of deforestation and may be one of the pioneers in using exotic tree plantations for forest restoration in Asia. In this study, we sampled herpetofaunal assemblages in native, secondary forests and exotic Lophostemon confertus plantations by transect surveys, pitfall traps, and coverboards. Amphibians were more abundant in secondary forests than in plantations, while the abundance of reptiles and species compositions of both amphibians and reptiles were similar in both forest types. Body condition of the most common reptile, Sphenomorphus indicus (Indian forest skink), was similar between secondary forests and plantations. However, higher proportions of S. indicus exhibited autotomized or missing tails in secondary forests than in plantations, which may be related to higher percentages of rock and wood cover on the forest floor potentially increasing the chance of escape from predators in secondary forests. Secondary forests may provide a better habitat for herpetofauna, we suggest that planting of a mixture of native tree species and thinning of exotic trees may be favorable management efforts to enhance biodiversity in future plantation in South China.

Nitrogen Addition Shapes Soil Phosphorus Availability in Two Reforested Tropical Forests in Southern China

AbstractScant information is available on how soil phosphorus (P) availability responds to atmospheric nitrogen (N) deposition, especially in the tropical zones. This study examined the effect of N addition on soil P availability, and compared this effect between forest sites of contrasting land‐use history. Effects of N addition on soil properties, litterfall production, P release from decomposing litter, and soil P availability were studied in a disturbed (reforested pine forest with previous understory vegetation and litter harvesting) and a rehabilitated (reforested mixed pine/broadleaf forest with no understory vegetation and litter harvesting) tropical forest in southern China. Experimental N‐treatments (above ambient) were the following: Control (no N addition), N50 (50 kg N ha−1 yr−1), and N100 (100 kg N ha−1 yr−1). Results indicated that N addition significantly decreased soil P availability in the disturbed forest. In the rehabilitated forest, however, soil P availability was significantly increased by N addition. Decreases in soil P availability may be correlated with decreases in rates of P release from decomposing litter in the N‐treated plots, whereas the increase in soil P availability was correlated with an increase in litterfall production. Our results suggest that response of soil P availability to N deposition in the reforested tropical forests in southern China may vary greatly with temporal changes in tree species composition and soil nutrient status, caused by different land‐use practices.

Changes in forest structure and composition on Changbai Mountain in Northeast China

Long-term ecological studies are essential for understanding the dynamics of natural systems. However, describing long-term dynamics in old-growth forests is often hindered by a lack of archival data. In this study, we investigated (1) changes in forest structure and tree species composition and (2) population dynamics of the dominant tree species over a 29-year period (1981–2010) in two old-growth forests with stand ages exceeding 200 years on Changbai Mountain in Northeast China. Results showed that the stem density of the broad-leaved/conifer mixed forest at 740 m asl increased slightly from 510 to 515 trees per hectare and the total basal area increased significantly from 36.19 to 46.53 m2 ha−1, suggesting that the forest was still maturing over the study period. However, the coniferous forest at 1,680 m asl displayed structural changes in the form of a significantly decrease in both stem density and total basal area over the study period. No changes in tree species composition in the two forests were observed. Wind was considered to be a frequent natural disturbance affecting the forest structure and dynamics, especially for the coniferous forest at the higher altitude. Dominant tree species in the two forests exploited different biological characteristics in maintaining their respective populations.

Seventy-year changes in tree species composition and tree ages in state-owned forests in Latvia

During the last 100 years, forest management in Latvia has gradually become more and more focused on industrial logging, which can be expected to have affected the tree species composition and age distribution across the landscape. These changes need to be considered in forest management and conservation of biological diversity. The aim of the study was to use forest records to reconstruct the tree species composition and age distribution in the North Vidzeme Biosphere Reserve in northern Latvia for the period, 1929–1941. These data were compared to a data-set from 2008, to determine the changes that transpired during a period of intensification of forest management. The silvicultural methods in the 1920–1941 period were based mostly on natural regeneration of logged stands. This led to succession to birch on harvested spruce stands and can explain the relatively large cover of mature birch stands today. After 1960, forest management was directed on conifer monocultures, and thus spruce stands today predominantly have age <50 years. An age class >150 years is almost absent for all species, and conservation should be directed to adding a portion of old forests to the protection network, and in maintaining the spatial continuity of overmature deciduous stands.

Changes in tree sapling composition within powerline corridors appear to be consistent with climatic changes in New York State

Despite emerging evidence that on-going climate change is affecting species physiology, distribution, and phenology, there are few studies that examine changes in tree sapling establishment as a response. Changes in tree species composition can be expected due to increasing temperatures, with subsequent effects on future forest compositions. This study's objective was to examine changes in relative density of tree species assemblages within powerline corridors from 1975 to 2003 in New York State. Powerline corridors in New York are commonly surrounded by forests, which creates constant tree invasion pressure within a perpetual old-field environment. This unique combination of factors allowed us to examine tree sapling establishment in a nearly constant environment over a 28-year period, utilizing manova and PCA as primary statistical analyses. Tree species dynamics varied across the four ecological provinces within New York over time. Northern pioneer species (Betula populifolia, Fraxinus americana, Prunus serotina, and Tilia americana) declined across the state over the past 28 years, while the southern pioneer species (Betula lenta, Liriodendron tulipifera, and Sassafras albidum) increased in the hot continental division. In the warm continental division, the pine-hemlock assemblage increased in the Northeastern Mixed Forest Province, while aspen-birch increased in the Adirondack Highlands Forest Province, likely due to increases in precipitation. It appears that climate change may have had some influence on tree sapling composition that could affect future vegetation management decisions and expectations in powerline rights-of-way and forests.

Streamflow responses to past and projected future changes in climate at the Hubbard Brook Experimental Forest, New Hampshire, United States

Climate change has the potential to alter streamflow regimes, having ecological, economic, and societal implications. In the northeastern United States, it is unclear how climate change may affect surface water supply, which is of critical importance in this densely populated region. The objective of this study was to evaluate the impact of climate change on the timing and quantity of streamflow at small watersheds at the Hubbard Brook Experimental Forest in New Hampshire. The site is ideal for this analysis because of the availability of long‐term hydroclimatological records for analyzing past trends and ample data to parameterize and test hydrological models used to predict future trends. In this study, future streamflow projections were developed with the forest watershed model PnET‐BGC, driven by climate change scenarios from statistically downscaled outputs of atmospheric‐ocean general circulation models. Results indicated that earlier snowmelt and the diminishing snowpack is advancing the timing and reducing the magnitude of peak discharge associated with snowmelt. Past increases in precipitation have caused annual water yield to increase significantly, a trend that is expected to continue under future climate change. Significant declines in evapotranspiration have been observed over the long‐term record, although the cause has not been identified. In the future, evapotranspiration is expected to increase in response to a warmer and wetter environment. These increases in evapotranspiration largely offset increases in precipitation, resulting in relatively little change in streamflow. Future work should aim to decrease uncertainty in the climate projections, particularly for precipitation, obtain a better understanding of the effect of CO2 on vegetation, determine if climate‐induced changes in tree species composition will influence discharge, and assess the impacts of changing hydrology on downstream water supplies.

Subcontinental impacts of an invasive tree disease on forest structure and dynamics

Summary 1. Introduced pests and pathogens are a major source of disturbance to ecosystems world‐wide. The famous examples have produced dramatic reductions in host abundance, including virtual extirpation, but most introductions have more subtle impacts that are hard to quantify but are potentially at least as important due to the pathogens’ effects on host reproduction, competitive ability and stress tolerance. A general outcome could be reduced host abundance with concomitant increases in the abundance of competitors. 2. Beech bark disease (BBD) is a widespread, fatal affliction of American beech (Fagus grandifolia), currently present in c. 50% of beech’s distribution in eastern North America. Despite high adult mortality, beech remains a dominant component of the forest community. 3. Employing spatially extensive data from the national Forest Inventory and Analysis program of the United States Forest Service, we show that forests have changed dramatically in the presence of BBD. Within the 2.3 million km2 range of beech, size‐specific mortality was 65% higher in the longest‐infected regions, and large beech (&gt;90 cm diameter at breast height) have declined from c. 79 individuals km−2 to being virtually absent. Small stem beech density was dramatically higher (&gt;350%) such that infested forests contain a roughly equivalent cross‐sectional (basal) area of beech as before BBD. 4. There was no evidence for compensation by sugar maple or other co‐occurring tree species via increased recruitment or adult survivorship at the landscape scale. Overall, community composition remained roughly unchanged as a result of BBD. 5. Surprisingly, trajectory of stand dynamics (shifts in stem density and mean tree size reflecting normal stand maturation (self‐thinning) or retrogression (more abundant, smaller trees over time)) did not differ between affected and unaffected regions. Variance in stand dynamics was greater in afflicted forests, however, indicating that predictability of forest structure has been diminished by BBD. 6. Synthesis. Forests of eastern North America have shifted to increased density and dramatically smaller stature – without notable change in tree species composition – following the invasion of a novel forest disease. Our results reinforce the conclusion that introduced diseases alter fundamental properties of ecosystems, but indicate that the spectrum of potential effects is broader than generally appreciated.

Forest Management in a Climate Change Era : Options for Planning(&lt;Special Issue&gt;Multipurpose Forest Management)

Changes in the world's climate may alter the state of forests across broad areas, through changes in tree species composition, tree productivity rates, and natural disturbance regimes. These potential changes may also have a cascading effect on associated environmental services, such water yield, wildlife habitat composition, and biodiversity. The location, extent, and magnitude of potential changes to the climate will vary according to current regional climatic conditions. For example, RAVINDRANATH et al. (2006) suggest that some areas of India will become wetter and warmer under one 100-year climate change scenario. This paper examines the issues facing forest planners in an era of climate change, and illustrates the challenges and opportunities for assessing climate change scenarios in forest planning efforts. For example, accounting for tree species physiology in forest planning would allow analysts to recognize that some tree species may be less able to adapt to changing conditions. And, adding socio-economic change projections (development and recreational opportunities) to the analysis of policies will further help one understand the potential impact of climate on biodiversity. These and other additional aspects of quantitative forest planning will enable land managers and decision-makers to think through the vulnerability of forests to changes in temperature, precipitation, and wind speed. In addition, forest plans may need to consider actions that will reduce forest fragmentation, conserve biologically important resources, and reduce the vulnerability of forests to the risks presented along with an assessment of traditional forestry concerns (sustainability of timber production, sustainability of multiple uses, and sustainability of ecosystems). Thus there seems to be a need to assess broad-scale forest management scenarios that minimize adverse impacts and vulnerability to the uncertainties associated with insect, disease, drought, windthrow, and wildfire. This type of planning process would need to account for changes in climatic variables and associated changes in disturbance regimes, and recognize that some forests may be more vulnerable during the adjustment period.

Long-term Changes in Forest Carbon and Nitrogen Cycling Caused by an Introduced Pest/Pathogen Complex

Invasion of exotic forest pests and pathogens is a serious environmental problem for many forests throughout the world, and has been especially damaging to forests of eastern North America. We studied the impacts of an exotic pest/pathogen complex, the beech bark disease (BBD), in the Catskill Mountains of New York State, USA. In this region, BBD has caused a decline in the basal area of American beech (Fagus grandifolia Ehrh.) over the last 60 years and this decline has been accompanied by an increase in the basal area of sugar maple (Acer saccharum Marsh.). We studied the impacts of the BBD on carbon (C) and nitrogen (N) cycling using a series of stands that represented a sequence of disease impact and beech replacement by sugar maple. Our study showed that these long-term changes in tree species composition can lead to important changes in C and N cycling in the ecosystem, including an increase in litter decomposition, a decrease in soil C:N ratio, and an increase in extractable nitrate in the soil and nitrate in soil solution. Rates of potential net N mineralization and nitrification did not change across the BBD sequence, but the fraction of mineralized N that was nitrified increased significantly. Many of the observed changes in ecosystem function are larger in magnitude than those attributed to climate change or air pollution, suggesting that the impacts of invasive pests and pathogens on tree species composition could be one of the most important factors driving changes in C and N cycling in these forests in the coming decades.

Landscape-level effects on avifauna within tropical agriculture in the Western Ghats: Insights for management and conservation

A critical handicap to tropical biodiversity conservation efforts in agroecosystems is the unknowns regarding the influence of landscape-scale factors on the persistence of species. To address these uncertainties, we explored two essential landscape-scale questions, within India’s biologically-rich Western Ghats, examining two nearby human-dominated landscapes that dramatically differed in their pattern of land cover. First, how does the proximity of intact forest patches affect bird community composition within agricultural landscapes? Second, can simple remote sensing-derived measures (brightness, wetness, and NDVI) be used to estimate native bird species composition within those landscapes? In both landscapes, as distance to intact forest decreased, the similarity in bird community composition between agricultural areas and intact forest increased. This suggests that the retention of tropical forest bird communities within human-dominated landscapes critically depends on the maintenance of nearby intact forest. In an answer to the second question, the remote sensing measures correlated with forest-affiliated avian species richness in only one of the two landscapes, reflecting an ecological difference between the two in the response of forest bird species to local agricultural conditions. In the landscape where a correlation was found, there was high variation in vegetative structure, which strongly impacted both the remote sensing measures and forest bird species richness. In the other landscape, forest species richness strongly correlated with changes in tree species composition in the agriculture, a factor that could not be detected by the remote sensing metrics. In order to successfully conserve biodiversity in tropical agricultural landscapes, our findings show that it is essential to conserve intact forest within those landscapes and to understand the effect of local agricultural practices on species.

Effect of tending and snow damage on changes in tree species composition, stand structure, qualitative and quantitative production of mixed spruce, fir and beech pole-stage stand on Stará Píla research plot

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Land-use and climate change effects in forest compositional trajectories in a dry Central-Alpine valley

• Increased mortality of Scots pine (Pinus sylvestris L.) and spreading of deciduous trees are observed in the Swiss Rhone valley. Previous research identified climate change effects as main drivers of this trend. On the local scale, we hypothesize that legacies from past anthropogenic disturbances are superimposed on climate effects. • We reconstructed land-use history and quantified changes in tree species composition from 1930 to 1994 on 9468 ha of forested land. The aim was to analyze the contribution of anthropogenic disturbances to the observed changes and to disentangle human impact from climate change effects. • At altitudes below 1 200 m a.s.l. we found a shift from pine (–11.4%) to deciduous trees (+11%) with significantly lower increase of deciduous trees in stands formerly used for grazing and/or litter collecting. Conversely, pine decrease was not correlated with former anthropogenic disturbances. We interpret pine mortality as an effect of increased drought stress due to climate change while spread of deciduous trees is driven by land-use change. Grazing and litter collecting hindered deciduous tree regeneration and it was not until their abandonment a few decades ago that forest composition started to change. At higher elevations the shift from Norway spruce (Picea abies; –8.5%) to European larch (Larix decidua; +8.2%) corresponds to silvicultural management schemes, aimed at promoting larch recruitment. • Our study illustrates the importance of disentangling climate from land-use change effects for understanding shifts in forest composition. The findings are relevant for other regions in the European Alps where forests undergo comparable environmental changes.

Effect of food quality and availability on rainforest rodents of Sri Lanka

Tropical rodent communities are highly diverse species assemblages, yet remain poorly studied. This investigation was conducted with the objective of examining the responses of rainforest rodents to food quality and availability. These factors were assessed through laboratory and field trials conducted in the Sinharaja and Kanneliya rainforests in Sri Lanka. The effect of food quality on the foraging behavior of rodents was examined through feeding experiments using natural rainforest fruits/seeds. In addition, the effect of food augmentation on the rodent population was also investigated. Diet choice experiments showed that rodents exhibited clear food preferences, with certain fruit types being preferentially consumed and others rejected. Tolerance tests where animals were provided with a single fruit type showed that some items that were avoided when offered with a range of food items were consumed when no alternatives were available. In the field a positive relationship was found between fruit/seed and rodent densities; seed addition resulted in marked increases in rodent numbers. These results suggest that tropical rodent populations are food limited, at least during seasons when fruits/seeds are in short supply. Food selectivity also means that populations of rainforest rodents might be adversely affected by changes in tree species composition resulting from habitat disturbance and fragmentation