Loss Of Trees Research Articles

Humans and elephants as treefall drivers in African savannas

Humans have played a major role in altering savanna structure and function, and growing land‐use pressure will only increase their influence on woody cover. Yet humans are often overlooked as ecological components. Both humans and the African elephant Loxodonta africana alter woody vegetation in savannas through removal of large trees and activities that may increase shrub cover. Interactive effects of both humans and elephants with fire may also alter vegetation structure and composition. Here we capitalize on a macroscale experimental opportunity – brought about by the juxtaposition of an elephant‐mediated landscape, human‐utilized communal harvesting lands and a nature reserve fenced off from both humans and elephants – to investigate the influence of humans and elephants on height‐specific treefall dynamics. We surveyed 6812 ha using repeat, airborne high resolution Light Detection and Ranging (LiDAR) to track the fate of 453 685 tree canopies over two years. Human‐mediated biennial treefall rates were 2–3.5 fold higher than the background treefall rate of 1.5% treefall ha–1, while elephant‐mediated treefall rates were 5 times higher at 7.6% treefall ha–1 than the control site. Model predictors of treefall revealed that human or elephant presence was the most important variable, followed by the interaction between geology and fire frequency. Treefall patterns were spatially heterogeneous with elephant‐driven treefall associated with geology and surface water, while human patterns were related to perceived ease of access to wood harvesting areas and settlement expansion. Our results show humans and elephants utilize all height classes of woody vegetation, and that large tree shortages in a heavily utilized communal land has transferred treefall occurrence to shorter vegetation. Elephant‐ and human‐dominated landscapes are tied to interactive effects that may hinder tree seedling survival which, combined with tree loss in the landscape, may compromise woodland sustainability.

Tropical forest-transition landscapes: a portfolio for studying people, tree crops and agro-ecological change in context

ABSTRACTNudging the development trajectory of tropical landscapes towards sustainability requires a global commitment and policies that take diverse contexts and forest transitions into account. Out-scaling and upscaling landscape-level actions to achieve sustainable development goals globally need to be based on understanding of extrapolation domains and interconnectivity of products and services. We evaluated three portfolios of tropical landscape observatories and quantified extrapolation domains across ecological zones, stages of forest transition, human development index (HDI), population density and potential prominence of four dominant tropical tree crops (arabica coffee, cacao, rubber and oil palm). The ASB Partnership for Tropical Forest Margins portfolio was focussed on active humid forest margins and the Poverty and Environment Network on early stages of forest transition. The portfolio of sentinel landscapes of the Forests, Trees and Agroforestry (FTA) research programme provides a 5% sample of pantropical area, 8% of people, 9% of tree cover and 10–12% of potential tree crop presence, with quantified biases across zones, transition stages and HDI. In the ‘water tower’ configuration, relatively high population density coincides with biodiversity, coffee expansion and contested ecosystem services. The extrapolation domain of the FTA portfolio includes trade-off (tree loss) and synergy (restoration) phases of tropical forest transition.EDITED BY Paolo Omar Cerutti

Long-term recovery from fire by a population of honey possums (Tarsipes rostratus) in the extreme south-west of Western Australia

The impact of two fires, six years apart, on the long-term recovery of a population of honey possums (Tarsipes rostratus) in the extreme south-west of Western Australia was documented over a 23-year period. Recovery was relatively rapid after the first fire, with catch rates reaching 78% of precatch levels within six years, but was much slower following the second fire in April 1999. Regression analysis estimates that full recovery to prefire catch rates and densities would take 25.6 years. The spread of Phytophthora cinnamomi (dieback) throughout the study area has severely impacted Banksia ilicifolia trees, which are the honey possums’ primary food source, and the impact has been greater in the burnt than unburnt areas. Analysis of catch-per-unit-effort and density of individual honey possums over the whole 29-year period of the study shows that numbers have not declined in the long-unburnt southern area of the study site, despite the spread of dieback and loss of banksia trees. The data are discussed in relation to the impact of fire on other vertebrate species that have specific habitat requirements. Given predictions of increasing fire frequencies due to climate change and an increased utilisation of prescribed burning to protect human life and property, it is imperative that management of areas harbouring honey possums be protected from too-frequent fire if this iconic species is to persist.

The Once and Future Great Lakes Country: An Ecological History by John L. Riley

Reviewed by: The Once and Future Great Lakes Country: An Ecological History by John L. Riley Theodore J. Karamanski John L. Riley, The Once and Future Great Lakes Country: An Ecological History. Montreal, Canada: McGill-Queen’s University Press, 2013. 488pp. $39.95. John L. Riley has written an ambitious, thoughtful, and useful book that ranges from the ice ages to the impact of modern globalization on the Great Lakes region. Yet it is also an eccentric and uneven approach to a subject that is admittedly daunting in scope and complexity. Riley is a scientist with a diverse background in botany, geology, and ecology. This often allows him to bring to bear a range of knowledge and insights into environmental change that is beyond the grasp of most environmental historians. As the chief science advisor to the Nature Conservancy of Canada and a lifelong resident to Ontario he has an intimate knowledge of how wildlife populations and plant species have been shaped by human action in the only Canadian province situated on the Great Lakes. His book is less surehanded in dealing with the environmental history of the United States side of the lakes and with the political and economic policy history that has so influenced the way cities sprawl and invasive species spread. A strength of The Once and Future Great Lakes Country is its coverage of seventeenth, eighteenth and nineteenth century changes to the forests and wet lands that flank the basin of the inland seas. The discussion of First Nation and American Indian history in the region is excellent especially his chapter “Wilding the Land with War” that discusses the impact of the Iroquois wars and non-native disease on the flora and fauna of a broad swath of [End Page 113] the region from what had been Huronia and across the Michigan peninsula. Riley gives the reader the best available terrestrial wildlife history of the region. Unfortunately he sometimes seems so enamored with the accounts of early explorers and travelers that he indulges in long pages of descriptions of the plentitude of fish and game in contact period North America. Much of this description is not even of the Great Lakes region but of New England and the Gulf of St. Lawrence ranging out even to Newfoundland and the shores of Hudson’s Bay. Yet when Riley gets back to the Great Lakes region the reader is rewarded with a picture of a regional ecology that has ever been in flux. The Great Lakes region explored by Jean Nicolet in the 1630s was significantly different than that of Antoine de Lamothe Cadillac in the eighteenth century or John Muir in the nineteenth century. A touchstone for the volume is a small piece of former agricultural land in Mono Township, Ontario on elevated ground between Lake Ontario and Lake Huron. In his youth Riley used a timely inheritance to buy a rundown farm there. “The story of Nature writ large,” he writes, “on the wider landscape—of collapse and restoration—I see through the lens of a farm that is just like a thousand others” (xvi). He periodically returns the reader to this single piece of land to reflect on reforestation, the return of predators such as the cougar to the region, or the impact of beech-bark scale insects. The device establishes Riley’s passion for the landscape and rooted commitment to it. It also reflects something this reviewer regards as weakness of the book. The Once and Future Great Lakes Country is rooted in the land. The great inland seas that are the heart of the region and lend name and identity to the region take a decided backseat to Riley’s narration of changing vegetation, settlement, and wildlife. For example, Riley devotes considerable attention to the forests of the region. He knowledgably discusses market driven deforestation in the nineteenth century, the type of species that dominated the partial reforestation that occurred in the twentieth century, and the harrowing loss of native trees to Eurasian insects and fungi in the twenty-first century. Yet the reader is given only a superficial review of the impact of invasive species on the Great Lakes. The zebra mussel...

Did the 2002 Hayman Fire, Colorado, USA, Burn with Uncharacteristic Severity?

There is considerable interest in evaluating whether recent wildfires in dry conifer forests of western North America are burning with uncharacteristic severity—that is, with a severity outside the historical range of variability. In 2002, the Hayman Fire burned an unlogged 3400 ha dry conifer forest landscape in the Colorado Front Range, USA, that had been the subject of previous fire history and forest age structure research. We opportunistically leveraged pre-existing data from this research, in combination with post-fire aerial imagery, to provide insight into whether the Hayman Fire’s patterns of high-severity, stand-replacing fire effects were uncharacteristic. Living old overstory trees were well distributed and abundant in the landscape before the Hayman Fire, despite the fact that some stand-replacing burning had been a component of the landscape’s historical mixed-severity fire regime. Of 106 randomly selected stand polygons that were sampled for the age of the oldest living overstory tree prior to the fire, 30% contained only trees ≤200 yr, while 70% contained at least one tree >200 yr and 29% contained at least one tree >400 yr. Following the Hayman Fire, only 5% of the polygons contained any living trees; these polygons were all immediately adjacent to the reservoir in the center of the landscape. At most, 4% of the polygons contained one or more trees >200 yr post fire, and 3% contained one or more trees >400 yr. The nearly complete loss of old trees, most of which were located in areas with evidence of past non-stand-replacing burning, leads us to conclude that the amount and extent of stand-replacing burning within the Hayman Fire were uncharacteristic for this landscape over at least the last two to four centuries.

Water deficit mechanisms in perennial shrubs Cerasus humilis leaves revealed by physiological and proteomic analyses.

BackgroundDrought (Water deficit, WD) poses a serious threat to extensively economic losses of trees throughout the world. Chinese dwarf cherry (Cerasus humilis) is a good perennial plant for studying the physiological and sophisticated molecular network under WD. The aim of this study is to identify the effect of WD on C. humilis through physiological and global proteomics analysis and improve understanding of the WD resistance of plants.MethodsCurrently, physiological parameters were applied to investigate C. humilis response to WD. Moreover, we used two-dimensional gel electrophoresis (2DE) to identify differentially expressed proteins in C. humilis leaves subjected to WD (24 d). Furthermore, we also examined the correlation between protein and transcript levels.ResultsSeveral physiological parameters, including relative water content and Pn were reduced by WD. In addition, the malondialdehyde (MDA), relative electrolyte leakage (REL), total soluble sugar, and proline were increased in WD-treated C. humilis. Comparative proteomic analysis revealed 46 protein spots (representing 43 unique proteins) differentially expressed in C. humilis leaves under WD. These proteins were mainly involved in photosynthesis, ROS scavenging, carbohydrate metabolism, transcription, protein synthesis, protein processing, and nitrogen and amino acid metabolisms, respectively.ConclusionsWD promoted the CO2 assimilation by increase light reaction and Calvin cycle, leading to the reprogramming of carbon metabolism. Moreover, the accumulation of osmolytes (i.e., proline and total soluble sugar) and enhancement of ascorbate-glutathione cycle and glutathione peroxidase/glutathione s-transferase pathway in leaves could minimize oxidative damage of membrane and other molecules under WD. Importantly, the regulation role of carbohydrate metabolisms (e. g. glycolysis, pentose phosphate pathways, and TCA) was enhanced. These findings provide key candidate proteins for genetic improvement of perennial plants metabolism under WD.Electronic supplementary materialThe online version of this article (doi:10.1186/s12953-017-0117-1) contains supplementary material, which is available to authorized users.

Changes in the stands of the Białowieża National Park from 2000 to 2015

AbstractThe aim of the study was to characterise changes in the natural forest of the Białowieża National Park (BNP) Strict Reserve during a 15-year period. To allow for a more precise determination of the time course, overall duration and intensity of the observed changes, the 15-year period was further divided into shorter 2-7-year intervals. Taken together, the Strict Reserve forest stands cover 4584 hectares and they constitute the oldest part of the Białowieża Forest placed under protection in 1921.The measurements were carried out in 2000, 2002, 2004, 2011 and 2015 on 160 permanent sample plots, which are systematically distributed throughout the BNP Strict Reserve. During those 15 years, the volume of merchantable timber and the tree density fluctuated only slightly, because the reduction in standing volume due to a spruce and ash decline was compensated for by an increase in the standing volume of lime, hornbeam and alder. The volume increment and tree loss fluctuated slightly, but were nevertheless similar throughout the whole period between 2000 and 2015. The number of trees in the regeneration layer increased. The number of hornbeam trees in this layer increased continuously throughout the whole measurement period, while the number of maple trees started to increase in the second half. All together only five tree species growing in the BNP Strict Reserve progressed from the regeneration layer to the canopy layer in significant numbers. As a result, a gradual decrease in species diversity of forest stands may be expected.The rather stable, average volume of merchantable timber in the BNP Strict Reserve may be due to the fact that, in a forest with diverse habitats and high species richness, only a few stands are subjected to strong disturbances in a given period of time. Repeated measurements during a relatively short period of time allowed the detecting some fairly quick changes occurring in natural lowland forests.

Northern flickers only work when they have to: how individual traits, population size and landscape disturbances affect excavation rates of an ecosystem engineer

Woodpeckers are considered ecosystem engineers because they excavate tree cavities which are used subsequently by many species of secondary cavity nesters for breeding. Woodpeckers have the choice of excavating a new hole or reusing an existing one, and this propensity to excavate (e) may affect community dynamics but has rarely been investigated. Using 18 years of data on a population of northern flickers Colaptes auratus, I tested six hypotheses to explain the propensity to excavate (e) in a landscape which experienced two types of disturbance: pine beetles and wildfires. Woodpecker age, breeding experience and mate retention had little influence on e which varied between 13–39% annually and averaged 23% for 1843 first nests over the 18 yr. Body size and body condition of males and females were not associated with e but rates of excavation declined seasonally, suggesting time rather than energy costs limited excavation effort. Reduced cavity availability mediated through high conspecific density coupled with wildfires triggered relatively high excavation rates, up to 39% but e decreased to baseline levels three years after the landscape disturbances. Nearly 2/3 of males did not excavate in their lifetime but apparently, e is great enough to balance the average rate of cavity tree loss in this forest which is 11% annually. Excavation propensity in flickers is flexible, but the birds reduce their work levels if there is a surplus of holes available.

Drivers of Tree Growth, Mortality and Harvest Preferences in Species-Rich Plantations for Smallholders and Communities in the Tropics

There is growing interest in multi-species tropical plantations but little information exists to guide their design and silviculture. The Rainforestation Farming system is the oldest tropical polyculture planting system in the Philippines and provides a unique opportunity to understand the underlying processes affecting tree performance within diverse plantings. Data collected from 85 plots distributed across the 18 mixed-species plantations in the Philippines was used to identify the factors influencing growth, probability of harvest, and death of trees in these complex plantings. The 18 sites (aged from 6 to 11 years at time of first measurement) were measured on three occasions over a 6-year period. We used data from the first period of data collection to develop models predicting harvesting probability and growth of trees in the second period. We found little evidence that tree species diversity had an effect on tree growth and tree loss at the community level, although a negative effect was found on tree growth of specific species such as Parashorea plicata and Swietenia macrophylla. While tree density of stands at age 10+ years (more than 1000 trees/ha with diameter > 5cm) did not have an impact on growth, growth rates were decreasing in stands with a high basal area. Tree size in the first period of measure was a good predictor for both tree growth and tree status in the next period, with larger trees tending to grow faster and having a greater chance of being harvested, and a lower possibility of mortality than smaller trees. Shade-intolerant trees were both more likely to be harvested, and had a higher probability of death, than shade-tolerant individuals. Native species and exotic species were equally likely to have been lost from the plots between measurement periods. However, shade-tolerant native trees were likely to grow faster than the others at age 10+ years. Our findings suggest that species traits (e.g. shade tolerance) could play an important role in optimizing species composition for this type of plantation. Shade-intolerant species with rapid early growth could contribute early income for farmers in mixed plantings where some products may take years to realize. We also suggest selective harvesting or thinning (for small shade-intolerant trees) applied at age 10+ years could reduce the competition for resources between individuals.

The effect of wildfire on scattered trees, ‘keystone structures’, in agricultural landscapes

AbstractScattered trees are considered ‘keystone structures’ in many agricultural landscapes worldwide because of the disproportionate effect they have on ecosystem function and biodiversity. Populations of these trees are in decline in many regions. Understanding the processes driving these declines is crucial for better management. Here, we examine the impact of wildfire on populations of this keystone resource. We examined 62 observation plots affected by wildfire and matched with 62 control observation plots where fire was absent. Counts of scattered trees were conducted pre‐fire in 2005 and repeated post‐fire in 2011. Changes in populations were compared between the control and fire‐affected observation plots. Our results show wildfire had a significant local impact, with an average decline of 19.9% in scattered tree populations on burned plots. In contrast, scattered trees increased on average by 5.3% in the control observation plots. The impact of wildfire was amplified (as revealed by greater percentage tree losses) by larger wildfires. Wildfire effects on scattered tree populations are of concern, given a background of other (usually) chronic stressors (often associated with agriculture) and that the frequency and intensity of wildfire are predicted to increase in many landscapes.

An examination of the potential efficacy of high‐intensity fires for reversing woody encroachment in savannas

Summary Frequent fires are often proposed as a way of preventing woody encroachment in savannas, yet few studies have examined whether high‐intensity fires can effectively reverse woody encroachment. We applied successive fire treatments to examine the effect of fire intensity on woody vegetation structure. The treatments included early dry season, low‐intensity fires; late dry season, higher‐intensity fires; and an unburnt control. We used pre‐ and post‐fire airborne LiDAR to compare vegetation structural changes brought about by fires of different intensity. Early dry season fires were of lower intensity (1400–2100 kW m−1) than late dry season fires (2500–4300 kW m−1). The two treatments also differed in terms of fuel consumed, scorch heights and char heights, indicating that clear differences in fire intensity and severity were achieved. After 4 years and two fire applications, relative woody cover increased by between 20 and 110% in different height categories following low‐intensity and control treatments and declined by between 3 and 70% following high‐intensity fire treatments. Declines were markedly higher following two repeated high‐intensity fires than following a high and then a moderate‐intensity fire. Because woody shrubs in lower height classes can recover rapidly, repeated high‐intensity fires would be needed to maintain lower cover. Tall trees are often assumed to be unaffected by fires. However, we found that the rate of tree loss was directly related to fire intensity, where 36% of trees were lost following repeated high‐intensity fires, compared to 22% after a high‐ and then a moderate‐intensity fire and 6% after two low‐intensity fires (3% without fire). Synthesis and applications. Using LiDAR data we show that high‐intensity fires can, at least in the short term, significantly reduce woody cover in South African savannas. The use of repeated high‐intensity fires simultaneously causes both a positive (reduction in cover of short shrubs) and a negative (loss of tall trees) outcome, and managers need to make trade‐offs when contemplating the use of fire intensity to achieve specific goals. One potential solution may be to repeatedly apply high‐intensity treatments to some areas, and not to others. This could generate a heterogeneous landscape where grasses become dominant and tall trees become scarce in some places, but in others, tall trees persist (or at least decline at slower rates), and shorter woody shrubs increase in dominance. Whether this would be acceptable, or practical, remains to be tested.

The transition of Wytham Woods from a working estate to unique research site (1943–1965)

ABSTRACTDiaries written by Charles Elton and other unpublished material from 1942–1965 illustrate the state of Wytham Woods and debates about its management in the first two decades after the estate came into the ownership of Oxford University. They reveal a legacy of wartime activity, the problems of rabbit control and the tensions between the different departments in the University. The Forestry Department sought to manage most of the Woods as a resource for teaching the then prevailing ideas of modern productive forestry: most of the Woods should therefore be converted to plantation. Elton and others regarded the rates of felling and replanting, the loss of old trees, as a serious threat to the value of the Woods from an ecological research perspective. In 1961, the University sided with the ecologists and active forestry management largely ceased. The legacy of this period survives though in the composition and structure of the Woods today. The issues and debates at Wytham foreshadow many of those that took place in the 1970s and 1980s between foresters and conservationists more generally across Britain.

Natural tree regeneration in agricultural landscapes: The implications of intensification

Concern about food security is prompting a push to intensify agriculture globally. However, agricultural intensification can inhibit regeneration of vegetation in natural ecosystems. This may jeopardise the persistence of trees in agricultural landscapes and the ecosystem services these treed landscapes offer. Here, we study one of the world’s most altered ecosystems – temperate eucalypt woodlands – to explore patterns in natural regeneration of trees, and factors influencing regeneration occurrence, across 300000km2 of south-eastern Australia between 2008 and 2014. During this period, we found the proportion of remnants supporting natural regeneration was stable, and that regeneration occurrence was negatively associated with variables coincident with agricultural intensification: continuous livestock grazing by sheep and cattle, increased exotic plant cover, increased natural soil fertility, and lower elevation. These results indicate that intensive agriculture is incompatible with natural regeneration in our study area. Left unaddressed, low levels of regeneration may result in the widespread loss of trees and the ecosystem services they provide in agricultural landscapes. Thus, strategic implementation of land-sparing and land-sharing strategies is required across broad spatial scales to satisfy production and conservation needs. Based on our results, we recommend that land sharing be prioritised where: (1) livestock grazing can be removed or employed intermittently, (2) exotic plants do not dominate the ground layer, and (3) natural soil fertility is low. For locations that are continuously grazed or dominated by exotic plants, a land-sparing strategy may be more appropriate. Here, farmland should be managed to maximise production, and the next generation of trees should be ‘moved’ to areas where natural regeneration can be supported.

Modeling trees internal tissue for estimating electrical leakage current

A part of power distribution system losses is related to the growth of trees beside power lines. Despite the fact that the first need for the reduction of tree losses is an accurate evaluation, a detailed study has not been done in this field thus far. Earlier works about trees interfering with power lines have not considered power loss and often studied it as a high impedance fault problem. In addition, these studies have been just focused on the leakage current measurement of some specific trees touching medium voltage distribution network, while it is low voltage network in urban and rural areas that has maximum reports of tree contact. Furthermore, the amount of leakage current greatly depends on the internal tissues of trees and environmental conditions. With regard to the differences in tree types and weather conditions around the world, losses will have different degrees; therefore, studies cannot be confined only to the results of some particular types of trees. Considering the shortcomings of these studies, this paper tries to determine a factor for environmental conditions. By applying this factor, the leakage current values for different weather conditions are estimated. Besides, this paper uses 3D finite element method for modeling tree losses by considering type of trees. For assessing the validity of the modeling results, the range of leakage currents is obtained from experiments in a real low voltage network. The results of this study remove doubt about the reliability of loss calculation and shows that loss estimation by modeling is an effective and reliable tool in this field.

Nonnative forest insects and pathogens in the United States: Impacts and policy options.

We review and synthesize information on invasions of nonnative forest insects and diseases in the United States, including their ecological and economic impacts, pathways of arrival, distribution within the United States, and policy options for reducing future invasions. Nonnative insects have accumulated in United States forests at a rate of ~2.5 per yr over the last 150 yr. Currently the two major pathways of introduction are importation of live plants and wood packing material such as pallets and crates. Introduced insects and diseases occur in forests and cities throughout the United States, and the problem is particularly severe in the Northeast and Upper Midwest. Nonnative forest pests are the only disturbance agent that has effectively eliminated entire tree species or genera from United States forests within decades. The resulting shift in forest structure and species composition alters ecosystem functions such as productivity, nutrient cycling, and wildlife habitat. In urban and suburban areas, loss of trees from streets, yards, and parks affects aesthetics, property values, shading, stormwater runoff, and human health. The economic damage from nonnative pests is not yet fully known, but is likely in the billions of dollars per year, with the majority of this economic burden borne by municipalities and residential property owners. Current policies for preventing introductions are having positive effects but are insufficient to reduce the influx of pests in the face of burgeoning global trade. Options are available to strengthen the defenses against pest arrival and establishment, including measures taken in the exporting country prior to shipment, measures to ensure clean shipments of plants and wood products, inspections at ports of entry, and post‐entry measures such as quarantines, surveillance, and eradication programs. Improved data collection procedures for inspections, greater data accessibility, and better reporting would support better evaluation of policy effectiveness. Lack of additional action places the nation, local municipalities, and property owners at high risk of further damaging and costly invasions. Adopting stronger policies to reduce establishments of new forest insects and diseases would shift the major costs of control to the source and alleviate the economic burden now borne by homeowners and municipalities.

Analysis of socio-environmental impacts of the loss of urban trees and vegetation in Lahore, Pakistan: a review of public perception

In the original publication of this article (Shirazi et al., 2016) the author figured out that in the Fig. 1, the upper left corner Map of Pakistan was inappropriate as per the national policy. In map of Pakistan, Jammu & Kashmir (occupied by India) must be shown annexed with Pakistan while mentioning Azad Jammu & Kashmir as disputed territory.

Environmental Impact Assessment of Kol-Dam Hydropower Project – A Case Study from Himachal Pradesh, India

The study was conducted during 2011 to investigate the impacts of Kol-dam construction on people and their overall economy. There was a loss of total land holding per family in the range of 33.07 to 64.46 per cent in 5 affected villages selected for the study. However in case of cultivated land there was a loss in the range of 36.15 to 67.36 per cent in 5 sampled villages. Submergence of land resulted in the loss of different trees (fodder, timber, fuel wood and fruit) from villages’ farmland in the range of 37.45 to 80.60 per cent in 5 affected village. There was a substantial decrease in the livestock population which ranged from 52.50 to 59.60 per cent. Construction of dam resulted in loss of assets to the extent of 33.33 to 45.45 percent in different villages. Overall there was a decrease in on-farm sectors (crop & livestock) ranged from 42.86 to 81.17 per cent whereas an increase in off- farm income (jobs and private business) ranges from 13.33 - 48.33 per cent has been observed from the affected villages. Hence it can be concluded that there was a loss of on-farm income resources like agriculture land and its associated resources i.e. important tree species and livestock. This might have serious impact on local biodiversity as well as on the life style of project affected families.

Citrus Reset Management

Replacement of dead and diseased trees in Florida citrus groves has always been an important part of citrus production. Today, tree replacement is more important than ever since overhead and production costs are escalating and a full stand of productive trees is essential to maximize production and profits. In more recent times, Huanglongbing (HLB), or citrus greening, has accelerated tree loss rates as well as the ability for growers to bring young citrus trees into production. This revised 5-page fact sheet discusses a wide range of techniques for providing young tree care. Many of these should prove useful to Florida citrus growers confronted with the problem of managing resets. Written by Stephen H. Futch, and published by the Horticultural Sciences Department, September 2015. HS142/CH025: Citrus Reset Management (ufl.edu)

Brown Creeper (Certhia americana) demographic response to hardwood forests managed under the selection system

The Brown Creeper (Certhia americana Bonaparte, 1838) has been identified as one of the most sensitive passerines to partial forest harvest in North America. The effect of selection logging on Brown Creeper density, nest timing, nest survival, and nest and foraging site selection was examined in five silviculture treatments (intensive group selection, typical group selection, old single-tree selection, recent single-tree selection, and control forests) of Algonquin Provincial Park, Canada. As Brown Creeper nests under the bark of large, decaying trees, we hypothesized that Brown Creeper density, timing of breeding, nest survival, and nest and foraging site selection would be negatively affected by silviculture through the removal of large, decaying trees as part of providing safe conditions for loggers. We monitored 101 nests of Brown Creeper during the 2010 and 2011 breeding seasons, mapped territories to estimate density, and conducted foraging surveys. Brown Creeper density was reduced by about 42% in logged stands compared with control stands. Despite that, silviculture did not significantly alter timing of breeding or nest survival. However, the loss of large trees through partial harvesting meant that Brown Creeper nested closer to adjacent, small forested wetlands and often in balsam fir (Abies balsamea (L.) Mill.) in treated stands. In control stands, Brown Creeper nested further from forested wetlands, disproportionately in greater numbers in upland hardwoods, and preferentially in the bark of snags of yellow birch (Betula alleghaniensis Britton). The change in the species of tree used for nesting and the general forest type as a result of logging also resulted in consequences for the selection of foraging substrates. To maintain higher densities of Brown Creeper in logged stands in Algonquin Park, we recommend retaining larger diameter yellow birch, both snags and live trees, preferably within strategically located uncut reserves based on habitat supply planning, that maintains patches roughly the size of Brown Creeper territories (10 ha).

Epiphytic orchids and their ecological niche under anthropogenic influence in central Himalayas, Nepal

The survival chance of epiphytic orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions: (1) What is the ecological niche of the different epiphytic orchid species? (2) What are the ecological factors that threaten epiphytic orchid’s population under anthropogenic disturbances? Our study area was the Kathmandu valley, Nepal, with its subtropical forest.We established 156 systematically selected sampling points in the Kathmandu area covering different types of ecosystems under human impacts such as densely populated area, agricultural land, mixed agricultural and settled area, old tree patches, and a natural forest in a national park. The ecological niche of the orchid species was analyzed with a principal component analysis (PCA). The correlations between the different site factors were statistically significant. Spearman’s rank correlation matrices showed that the variables land-use intensities with altitude, and height with diameter in breast height (dbh) of host had the highest significant positive correlation coefficient (0.67 and 0.64 respectively). On the other hand, host bark pH and altitude as well as land use had a significantly strong negative correlation coefficient (-0.80 and -0.61, respectively). Different epiphytic orchid species interact differently with the given set of environmental factors: for occurrence of Vanda cristata there is no single environmental factor of special influence, while for Rhynchostylis retusa high bark pH and high light availability are important. First two axis of the PCA explained more than 50% of the total variance. Most orchid species occupy a specific, narrow niche in this ecological space. The main causes of anthropogenic influence of orchid population in the Kathmandu Valley are loss of adequate host trees (species and size) and increasing air pollution, resulting in increasing host bark pH.