ABSTRACT Invasive alien species (IAS) are considered to be a main and a direct driver of biodiver... more ABSTRACT Invasive alien species (IAS) are considered to be a main and a direct driver of biodiversity loss across the globe, and Sri Lanka is not an exception. These IAS have been estimated to cost our economies enormously every year and is a major threat to sustainable development. All alien species will not become invasive or threaten the environment, however, alien always will have the nag with their potential to become invasive once escaped from human management. A clear policy approach is hence required for a country in order to effectively deal with the wide-ranging negative impacts of IAS, including the financial costs and irreversible effects on the environment. Sri Lanka is a signatory to the Convention on Biological Diversity (CBD), which clearly articulates the role play of the countries (article 8(h), to overcome the threats of IAS to the biodiversity. IAS are a problem in diverse ecosystems of Sri Lanka. The Biodiversity Secretariat of the Ministry of Environment of Sri Lanka, being the focal point for implementing the CBD in the country, has taken keen interest activities focusing on IAS control at various levels in the society. The national action plan for the Haritha Lanka programme published by the National Council for Sustainable Development (NCSD) of the Presidential Secretariat of Sri Lanka has identified management and control IAS as a necessity under its activity 8.2, while the Cabinet of Ministers of the country has approved (on 15th January 2009) the formulation of a Invasive Species Control act, thus indicating the high priority given by the country in this subject. However, still, it is evident that a proper coordinating mechanism with authority, responsibility and accountability, together with capacity building of stakeholders across all sectors, is a must for achieving the country’s long term goals in overcoming the impacts of IAS. This publication is aimed at providing necessary information to the scientists, academic, policy makers and other interested parties in understanding various aspects of IAS in Sri Lanka. This book comprises of 20 chapters out of which 13 chapters are devoted to assessing the present status in terms of definitions, national lists, risk assessment protocols, institutional arrangements, legal and policy frameworks, education and awareness strategies, IAS control efforts, etc., while the remaining 7 chapters deal with recent research activities on IAS. The information included in this book is up-to-date and it is our fervent hope that this publication will provide information to all those who are proactively taking part in the country’s efforts to free the ecosystems from the menace of IAS.
In recent years invasive species became a hot topic and biological invasions by alien species as ... more In recent years invasive species became a hot topic and biological invasions by alien species as one of the major threats to indigenous or native biodiversity in almost every country in the world. It was highly acknowledged by scientists and researchers. Therefore invaders are recognized as one of the major environmental problem globally. Sri Lanka is a small tropical island enriched with variety of unique ecosystems. Today several ecosystems of Sri Lanka have been affected by biological invasions affecting on environment and human life, such as biodiversity, agriculture and human health, social, cultural, economic and ecological processes. In order to manage the invaders one should require details of its distribution and rate of spreading and the best practices of controlling applications. This work is first attempt to map the "Myroxylon balsamum (L.) Harms" spread in Udawattakele Forest in Kandy district, Sri Lanka. The work intended to provide the forest manages vital i...
Abstract There is growing evidence for a positive non-linear response in N2O emissions where incr... more Abstract There is growing evidence for a positive non-linear response in N2O emissions where increasing N fertilizer rates critically exceed crop requirements from a range of cropping systems. However, the majority of these studies have been conducted in temperate regions, and it remains unclear if the non-linear response hypothesis can be transferred to tropical regions due to their inherently lower carbon (C) content and fertility. This study assessed the impact of different nitrogen (N) fertilizer application rates in combination with a carbon source (green-waste compost) on soil nitrous oxide (N2O) and carbon dioxide (CO2) emissions and crop productivity from a maize-soybean rotation in tropical Sri Lanka. Low cation exchange capacity and extremely high rainfall promoted higher annual cumulative N2O emissions than reported from other cropping systems, ranging from 2.4–9.16 kg N2O-N ha−1 yr−1 for the different fertilizer rates (0 N, 100 N, 220 N, 300 N). The ΔN2O emitted for every additional kilogram of fertilizer N applied (i.e. the marginal N2O emission), declined from ∼24 g kg−1 for the first 0−100 kg N applied to 7 g kg−1 at 300 kg N. This resulted in declining Emission Factors with increasing N rate, as factors other than N limited denitrification. The addition of compost removed this limitation, resulting in constant ΔN2O production rates and Emission Factors with increasing N inputs, suggesting low C availability limited N2O production at high N rates. The study shows that the non-linear response hypothesis might not hold for highly weathered tropical soils, where C availability limits N2O emissions at high N inputs. While the use of compost can be a viable option to increase soil fertility in these highly weathered tropical soils, it needs to be balanced with reduced N fertilizer application rates to avoid elevated losses of N2O.
Impacts of roadkills are extensively documented in developed nations. Only a handful of studies ... more Impacts of roadkills are extensively documented in developed nations. Only a handful of studies on road mortality has emerged from developing nations where tourism and rural development have led to an expansion of transportation networks. To fill such gaps, we conducted a survey to document roadkills in and around two tourism-heavy national parks of Sri Lanka and identified factors that contribute to road mortality. Based on a questionnaire, we interviewed 68 local villagers, 56 local and 59 foreign visitors, and 57 safari drivers to document their opportunistic observations on roadkills, their awareness about roadkills, and to understand potential causes of roadkills. We found 47 roadkilled vertebrate species at both parks; among these, 19 are threatened and 20 are endemic. Our research revealed that herpetofauna were killed the most. We concluded that increased visitation, high-speed driving, lack of awareness, and poor law enforcement as the likely causes of roadkills at bo...
Lantana camara L. (Verbenaceae) is an invasive alien species in many countries that causes econom... more Lantana camara L. (Verbenaceae) is an invasive alien species in many countries that causes economic losses and harmful ecological impacts on biodiversity. Its varieties with colourful flowers are being introduced to the horticulture trade in Sri Lanka despite that the orange-red flowered L. camara var. splendens and yellow-pink flowered L. camara var. camara introduced to the country in the nineteenth century have been naturalised and considered as invasive alien species of national significance. This study compared drought and shade tolerance abilities of white and purple flowered ornamental L. camara varieties with the above two naturalised varieties using statistical analysis. The results provided evidences for significant differences in drought and shade tolerance abilities between naturalised and ornamental L. camara varieties in Sri Lanka with regard to growth of the main stem, flowering, fruiting, defoliation, leaf water content and leaf growth rate, leaf area, photosynthetic tissue mass and pigment content, stomatal density, root volume and biomass partition between above and below ground parts. While contributing to fill in the knowledge gap in the biology of 'Lantana group', we report that ornamental L. camara varieties are not drought and shade tolerant as the naturalised varieties, and therefore their potential invasiveness may not be as high as the wild varieties that pose a great threat to the biodiversity of Sri Lanka.
Fragmentation has exposed the Kirigala forest to conditions of the forest and demonstrated its de... more Fragmentation has exposed the Kirigala forest to conditions of the forest and demonstrated its degradation × 5 m gradsects each accommodating 3 pairs of 10 m × 5 m plots, a total of 60 soil samples and 20 seed traps provided annual seed rain of the forest, respectively. Diversity of the edge and the forest interior were compared for the different neighbourhood land use types using the Shannon and Weiner (H) and Simpsons reciprocal (D) indices. Change in the forest in soil pH, soil moisture, nitrogen, available phosphorous and potassium, organic matter content, air temperature, humidity and light intensity between the forest edge and the interior were determined. Soil, microclimate and species richness were combined for clustering of similar areas. The site reported the presence of 55 tree, 12 shrub, 15 herb, 07 climber and 02 vine species including a total of 23 endemic species and 06 invasive species. A higher diversity was observed at the edge, and the highest was observed beside roads as indicated by both diversity indices H and D. Soil and microclimate of the practices. Dominance hierarchy of the trees was Dipterocarpus zeylanicus > Gaertnera vaginans > Aporusa lanceolata, while that for undergrowth/shrubs herbaceous species was Ochlandra stridula > Dracaena thwaitesii > Piper sylvestre. Annual seed rain contained propagules of 23 plant species, while invasive Alstonia macrophylla provided the highest density of seeds. Establishment of foot paths, selective removal of juveniles by root-balling technique and encroachment for crop cultivation have also facilitated the degradation process. It is vital to pay attention on maintaining the ecological stability of this forest before it loses its identity as the Hora Kele of Ingiriya.
Climate is the key driver of diversity of life in ecosystems. Changes in the climate, would not o... more Climate is the key driver of diversity of life in ecosystems. Changes in the climate, would not only alter the spatial distribution of species but also facilitate some of the non-native species to become invasive. This would further imbalance the status quo of native species and may bring about irreversible changes in some ecosystems imposing large economic costs for their management. Few researchers have addressed the issue of the interaction of climate change and invasive species in developing countries. We review the ecological impacts of invasive alien flora on the environment and the necessity to assess the economics of these impacts, particularly in developing countries. The potential implications of climate change on invasive alien flora relevant to Sri Lanka are discussed, highlighting how disturbances to ecosystems during climate change would facilitate the dispersal, establishment and spread of these invasive species and result in a change in the species distribution of native flora within ecosystems. The management of invasive alien species is already formulated for Sri Lanka. We draw attention to how climate change aspects should be incorporated into these management strategies. Important aspects to be considered are assessment of risk, targeting ecosystems vulnerable to climate change and mapping to monitor the location and progress of invasive flora.
ABSTRACT Invasive alien species (IAS) are considered to be a main and a direct driver of biodiver... more ABSTRACT Invasive alien species (IAS) are considered to be a main and a direct driver of biodiversity loss across the globe, and Sri Lanka is not an exception. These IAS have been estimated to cost our economies enormously every year and is a major threat to sustainable development. All alien species will not become invasive or threaten the environment, however, alien always will have the nag with their potential to become invasive once escaped from human management. A clear policy approach is hence required for a country in order to effectively deal with the wide-ranging negative impacts of IAS, including the financial costs and irreversible effects on the environment. Sri Lanka is a signatory to the Convention on Biological Diversity (CBD), which clearly articulates the role play of the countries (article 8(h), to overcome the threats of IAS to the biodiversity. IAS are a problem in diverse ecosystems of Sri Lanka. The Biodiversity Secretariat of the Ministry of Environment of Sri Lanka, being the focal point for implementing the CBD in the country, has taken keen interest activities focusing on IAS control at various levels in the society. The national action plan for the Haritha Lanka programme published by the National Council for Sustainable Development (NCSD) of the Presidential Secretariat of Sri Lanka has identified management and control IAS as a necessity under its activity 8.2, while the Cabinet of Ministers of the country has approved (on 15th January 2009) the formulation of a Invasive Species Control act, thus indicating the high priority given by the country in this subject. However, still, it is evident that a proper coordinating mechanism with authority, responsibility and accountability, together with capacity building of stakeholders across all sectors, is a must for achieving the country’s long term goals in overcoming the impacts of IAS. This publication is aimed at providing necessary information to the scientists, academic, policy makers and other interested parties in understanding various aspects of IAS in Sri Lanka. This book comprises of 20 chapters out of which 13 chapters are devoted to assessing the present status in terms of definitions, national lists, risk assessment protocols, institutional arrangements, legal and policy frameworks, education and awareness strategies, IAS control efforts, etc., while the remaining 7 chapters deal with recent research activities on IAS. The information included in this book is up-to-date and it is our fervent hope that this publication will provide information to all those who are proactively taking part in the country’s efforts to free the ecosystems from the menace of IAS.
In recent years invasive species became a hot topic and biological invasions by alien species as ... more In recent years invasive species became a hot topic and biological invasions by alien species as one of the major threats to indigenous or native biodiversity in almost every country in the world. It was highly acknowledged by scientists and researchers. Therefore invaders are recognized as one of the major environmental problem globally. Sri Lanka is a small tropical island enriched with variety of unique ecosystems. Today several ecosystems of Sri Lanka have been affected by biological invasions affecting on environment and human life, such as biodiversity, agriculture and human health, social, cultural, economic and ecological processes. In order to manage the invaders one should require details of its distribution and rate of spreading and the best practices of controlling applications. This work is first attempt to map the "Myroxylon balsamum (L.) Harms" spread in Udawattakele Forest in Kandy district, Sri Lanka. The work intended to provide the forest manages vital i...
Abstract There is growing evidence for a positive non-linear response in N2O emissions where incr... more Abstract There is growing evidence for a positive non-linear response in N2O emissions where increasing N fertilizer rates critically exceed crop requirements from a range of cropping systems. However, the majority of these studies have been conducted in temperate regions, and it remains unclear if the non-linear response hypothesis can be transferred to tropical regions due to their inherently lower carbon (C) content and fertility. This study assessed the impact of different nitrogen (N) fertilizer application rates in combination with a carbon source (green-waste compost) on soil nitrous oxide (N2O) and carbon dioxide (CO2) emissions and crop productivity from a maize-soybean rotation in tropical Sri Lanka. Low cation exchange capacity and extremely high rainfall promoted higher annual cumulative N2O emissions than reported from other cropping systems, ranging from 2.4–9.16 kg N2O-N ha−1 yr−1 for the different fertilizer rates (0 N, 100 N, 220 N, 300 N). The ΔN2O emitted for every additional kilogram of fertilizer N applied (i.e. the marginal N2O emission), declined from ∼24 g kg−1 for the first 0−100 kg N applied to 7 g kg−1 at 300 kg N. This resulted in declining Emission Factors with increasing N rate, as factors other than N limited denitrification. The addition of compost removed this limitation, resulting in constant ΔN2O production rates and Emission Factors with increasing N inputs, suggesting low C availability limited N2O production at high N rates. The study shows that the non-linear response hypothesis might not hold for highly weathered tropical soils, where C availability limits N2O emissions at high N inputs. While the use of compost can be a viable option to increase soil fertility in these highly weathered tropical soils, it needs to be balanced with reduced N fertilizer application rates to avoid elevated losses of N2O.
Impacts of roadkills are extensively documented in developed nations. Only a handful of studies ... more Impacts of roadkills are extensively documented in developed nations. Only a handful of studies on road mortality has emerged from developing nations where tourism and rural development have led to an expansion of transportation networks. To fill such gaps, we conducted a survey to document roadkills in and around two tourism-heavy national parks of Sri Lanka and identified factors that contribute to road mortality. Based on a questionnaire, we interviewed 68 local villagers, 56 local and 59 foreign visitors, and 57 safari drivers to document their opportunistic observations on roadkills, their awareness about roadkills, and to understand potential causes of roadkills. We found 47 roadkilled vertebrate species at both parks; among these, 19 are threatened and 20 are endemic. Our research revealed that herpetofauna were killed the most. We concluded that increased visitation, high-speed driving, lack of awareness, and poor law enforcement as the likely causes of roadkills at bo...
Lantana camara L. (Verbenaceae) is an invasive alien species in many countries that causes econom... more Lantana camara L. (Verbenaceae) is an invasive alien species in many countries that causes economic losses and harmful ecological impacts on biodiversity. Its varieties with colourful flowers are being introduced to the horticulture trade in Sri Lanka despite that the orange-red flowered L. camara var. splendens and yellow-pink flowered L. camara var. camara introduced to the country in the nineteenth century have been naturalised and considered as invasive alien species of national significance. This study compared drought and shade tolerance abilities of white and purple flowered ornamental L. camara varieties with the above two naturalised varieties using statistical analysis. The results provided evidences for significant differences in drought and shade tolerance abilities between naturalised and ornamental L. camara varieties in Sri Lanka with regard to growth of the main stem, flowering, fruiting, defoliation, leaf water content and leaf growth rate, leaf area, photosynthetic tissue mass and pigment content, stomatal density, root volume and biomass partition between above and below ground parts. While contributing to fill in the knowledge gap in the biology of 'Lantana group', we report that ornamental L. camara varieties are not drought and shade tolerant as the naturalised varieties, and therefore their potential invasiveness may not be as high as the wild varieties that pose a great threat to the biodiversity of Sri Lanka.
Fragmentation has exposed the Kirigala forest to conditions of the forest and demonstrated its de... more Fragmentation has exposed the Kirigala forest to conditions of the forest and demonstrated its degradation × 5 m gradsects each accommodating 3 pairs of 10 m × 5 m plots, a total of 60 soil samples and 20 seed traps provided annual seed rain of the forest, respectively. Diversity of the edge and the forest interior were compared for the different neighbourhood land use types using the Shannon and Weiner (H) and Simpsons reciprocal (D) indices. Change in the forest in soil pH, soil moisture, nitrogen, available phosphorous and potassium, organic matter content, air temperature, humidity and light intensity between the forest edge and the interior were determined. Soil, microclimate and species richness were combined for clustering of similar areas. The site reported the presence of 55 tree, 12 shrub, 15 herb, 07 climber and 02 vine species including a total of 23 endemic species and 06 invasive species. A higher diversity was observed at the edge, and the highest was observed beside roads as indicated by both diversity indices H and D. Soil and microclimate of the practices. Dominance hierarchy of the trees was Dipterocarpus zeylanicus > Gaertnera vaginans > Aporusa lanceolata, while that for undergrowth/shrubs herbaceous species was Ochlandra stridula > Dracaena thwaitesii > Piper sylvestre. Annual seed rain contained propagules of 23 plant species, while invasive Alstonia macrophylla provided the highest density of seeds. Establishment of foot paths, selective removal of juveniles by root-balling technique and encroachment for crop cultivation have also facilitated the degradation process. It is vital to pay attention on maintaining the ecological stability of this forest before it loses its identity as the Hora Kele of Ingiriya.
Climate is the key driver of diversity of life in ecosystems. Changes in the climate, would not o... more Climate is the key driver of diversity of life in ecosystems. Changes in the climate, would not only alter the spatial distribution of species but also facilitate some of the non-native species to become invasive. This would further imbalance the status quo of native species and may bring about irreversible changes in some ecosystems imposing large economic costs for their management. Few researchers have addressed the issue of the interaction of climate change and invasive species in developing countries. We review the ecological impacts of invasive alien flora on the environment and the necessity to assess the economics of these impacts, particularly in developing countries. The potential implications of climate change on invasive alien flora relevant to Sri Lanka are discussed, highlighting how disturbances to ecosystems during climate change would facilitate the dispersal, establishment and spread of these invasive species and result in a change in the species distribution of native flora within ecosystems. The management of invasive alien species is already formulated for Sri Lanka. We draw attention to how climate change aspects should be incorporated into these management strategies. Important aspects to be considered are assessment of risk, targeting ecosystems vulnerable to climate change and mapping to monitor the location and progress of invasive flora.
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