Forest floor calcium (Ca) declines in northern hardwood forests are of interest because Ca availability may limit future forest growth. In the 1990s investigations into Ca pools and fluxes across a northern hardwood forest chronosequence showed decreases across stand age in the mass of forest floor base cations and litterfall cation concentrations. I undertook a study of factors that influence litterfall chemistry to develop a better understanding of base cation biogeochemistry in developing northern hardwood forests. Although Ca, potassium (K), and magnesium (Mg) concentrations in litterfall significantly declined with stand age, species composition and soil nutrient availability also influenced litterfall chemistry. The interplay between these factors, such as the distribution of species with different nutrient demands in areas of base cation availability or limitation, influences forest floor chemistry and may impact the time in which soil Ca depletion occurs. Additionally, I examined the quantity and qualities (species composition, decay class, size, and nutrient concentrations and contents) of woody debris across the same northern hardwood forest chronosequence. The objectives of this study were to quantify cation pools in woody debris, describe how the qualities of these woody debris pools change with stand development, and establish a baseline for long-term measurements of woody debris accumulation and chemistry with stand age. Decomposition of woody debris transfers base cations to the forest floor, and may be partially responsible for forest floor Ca gains in young stands. Calcium and K pools in woody debris were most strongly influenced by woody debris biomass, whereas Mg content was influenced by both woody debris biomass and species composition. In young stands, woody debris pools were strongly influenced by management practices during harvest. By 20 years since harvest woody debris pools reflected processes of stand development. For example, from 20 to nearly 40 years since harvest woody debris biomass and species composition was dominated by mortality of early successional species. Woody debris in more mature stands reflected small-scale stochastic disturbances including disease and single-tree mortality. Litterfall and woody debris are each components of within-stand cation cycling that will be critical to future forest growth with limited Ca availability.

A modificação da paisagem e a fragmentação de habitats são consideradas ameaças à biodiversidade mundial. Áreas cobertas por vegetação primária ainda preservadas e unidades de conservação são insuficientes para garantir a conservação de espécies. Cultivos de florestas homogêneas passaram a ser considerados como possíveis habitats alternativos para espécies florestais e podem contribuir para a conservação da biodiversidade. O Brasil é o país com maior área ocupada com plantio de eucalipto e essa vem crescendo nos últimos anos. Identificar quais fatores influenciam a diversidade da biota nos plantios é importante para a conservação de espécies. O objetivo do presente estudo foi conhecer a composição florística do sub-bosque de plantios de Eucalyptus saligna Sm. e avaliar se o tipo de solo e a idade do plantio influenciam a riqueza e a composiçao da vegetação que ocupa esse ambiente. Para isso foi realizado o levantamento das espécies vegetais que ocorrem nos cultivos localizados em solo argiloso e arenoso, nos quais os indivíduos de E. saligna tinham três e sete anos. Foram avaliados como fatores ambientais características do solo, produção de serapilheira pelas árvores do plantio, abertura do dossel, uso do solo no entorno do cultivo e tamanho do plantio. No total, foram encontradas 218 espécies vegetais. As análises estatísticas foram realizadas apenas com as espécies que estavam presentes em pelo menos duas unidades amostrais. Plantios em solo argiloso apresentaram maior riqueza que no solo arenoso e houve diferença significativa na composição de espécies entre os dois tipos de solo. Grande parte dos fatores ambientais mensurados também foram diferentes entre os solos. Não foi possível verificar diferenças na riqueza, na composição de espécies e nos fatores ambientais entre os plantios de diferentes idades. O tipo de solo pode ser um fator mais limitante do que a idade da floresta plantada para determinar a riqueza e composição das espécies que compõem o sub-bosque dos plantios. Embora a riqueza de espécies no solo arenoso seja menor, esse também é importante para a conservação, porque abriga espécies adaptadas à menor disponibilidade de recursos, que não ocorrem em outros ambientes. O grande número de espécies encontrado no sub-bosque destes plantios indica que eles podem auxiliar na conservação de espécies nativas, mas esse potencial deve ser melhor investigado. São recomendados estudos de outros fatores, como a biologia de espécies importantes ecológica e econômicamente, interações entre animais e plantas e diferentes estratégias de manejo, para investigar de que forma eles afetam a biodiversidade e como eles podem ajudar a avaliar e aumentar o potencial de conservação das florestas industriais. / Landscape change and habitat fragmentaiton are recognized as threats to global biodiversity.Areas with remaining primary vegetation and protected areas are insufficient to ensure species conservation. Forest monocultures are potencial alternative habitats for native species and may contribute to the conservation of biodiversity. Brazil is the country with the largest area occupied with eucalypt plantations, this area is also growing in the last years. Identifying which factors influence the biodiversity on plantations is important to species conservation. The objective of this study was to know the understory species composition in Eucalyptus saligna Sm. plantations and to evaluate the influence of soil type and stand age on species richness and species composition. Surveys of vegetation were performed in stands on clay and sandy soils where the eucalypt trees were three and seven years old. Other soil characteristics, litter production by stand trees, canopy open and land use surrounding stands were evaluated as environmental factors. 218 plant species were found in plantations understory. The stands on clay soil were richer than those on sandy soil. Most of the environmental factors evaluated were also different among stands on different soils type. It was not possible to verify differences on species richness and species composition nor environmental factors between stand ages. Soil type could be a more limiting factor than forest age to determine species richness and species composition on plantations understory. Sandy soils are poorer in species, but they are also important to conservation, since species that happen on sandy soils are adapted to low resources availability and do not occur at other locations. The large number of native species founded in eucalypts plantation understory indicates that these plantations may assist some native species conservation. Nevertheless, further research is needed to understand the conservation potential from eucalypt plantations. It is recommended other studies to be done for a better comprehension and to increase the importance of plantation forests to conservation, mainly studies about biology of key species, interactions between animals and plants and the effect of different management options.

Climate change is predicted to increase rates of fire activity in boreal forests. A shortened fire return interval may result in different outcomes of community structure in the northern boreal forest, since the age of a forest influences seed production and potential post-fire regeneration. With two closely timed fires, dominant boreal conifers such as black spruce (Picea mariana) may be vulnerable to regeneration failures after fire because of the long time required to reach reproductive maturity. I report on the relationship between stand age and seed productivity of black spruce in northern Yukon Territory and central Alaska. I used fire history maps to select sites of various stand ages, including stand ages that would occur in a short fire return interval (less than 80 years) versus longer fire intervals (up to 200 years). At each site, I measured stand density and basal area using the point-center-quarter method. Ten black spruce trees were randomly selected for cone surveys and age analysis. I also selected a subset of five trees for detailed analyses of cone and seed production within yearly cohorts. The results of this study illustrate the strong relationships between stand age and stand basal area with cone and seed production of northern black spruce. The resulting equations can be used to predict the seed capacity and regeneration potential of black spruce stands with known stand basal area or stand age. I estimate, along with the number of seeds required to produce a two year old black spruce seedling on high quality seedbeds, stands burned at an age less than 50 years will likely have reduced black spruce post-fire density. On low quality seedbeds, black spruce forests are more vulnerable to regeneration failures and fire cycles less than 150 years are likely to result in reduced recruitment. Under a shortened fire return interval these northern black spruce forests are likely to have reduced post-fire density.

Climate change is predicted to increase rates of fire activity in boreal forests. A shortened fire return interval may result in different outcomes of community structure in the northern boreal forest, since the age of a forest influences seed production and potential post-fire regeneration. With two closely timed fires, dominant boreal conifers such as black spruce (Picea mariana) may be vulnerable to regeneration failures after fire because of the long time required to reach reproductive maturity. I report on the relationship between stand age and seed productivity of black spruce in northern Yukon Territory and central Alaska. I used fire history maps to select sites of various stand ages, including stand ages that would occur in a short fire return interval (less than 80 years) versus longer fire intervals (up to 200 years). At each site, I measured stand density and basal area using the point-center-quarter method. Ten black spruce trees were randomly selected for cone surveys and age analysis. I also selected a subset of five trees for detailed analyses of cone and seed production within yearly cohorts. The results of this study illustrate the strong relationships between stand age and stand basal area with cone and seed production of northern black spruce. The resulting equations can be used to predict the seed capacity and regeneration potential of black spruce stands with known stand basal area or stand age. I estimate, along with the number of seeds required to produce a two year old black spruce seedling on high quality seedbeds, stands burned at an age less than 50 years will likely have reduced black spruce post-fire density. On low quality seedbeds, black spruce forests are more vulnerable to regeneration failures and fire cycles less than 150 years are likely to result in reduced recruitment. Under a shortened fire return interval these northern black spruce forests are likely to have reduced post-fire density.

No description available.

Afforestation and stand development can significantly affect soil respiration and net ecosystem productivity (NEP). I studied 1) the effects of afforestation on NEP by comparing cropland previously planted to barley (on a barley-barley-alfalfa-alfalfa-alfalfa rotation) and that converted to a hybrid poplar (Populus deltoides Populus petrowskyana var. Walker) plantation and 2) the NEP along a chronosequence of stands aged 5-, 8-, 14-, and 16-year old in 2009 in central Alberta, Canada. Soil respiration and NEP decreased in the first two to three years after afforestation, while both generally increased with stand development. The ecosys model was used to simulate carbon dynamics in the plantations over a 20-year rotation under contrasting soil conditions. Soil conditions of the 14-year-old plantation accumulated the greatest amount of ecosystem carbon over the whole rotation. The research indicated that plantations could be a net carbon source in the first few years after afforestation and then became a net carbon sink, helping to mitigate net CO2 emissions for the remainder of the rotation. / Soil Science

A modificação da paisagem e a fragmentação de habitats são consideradas ameaças à biodiversidade mundial. Áreas cobertas por vegetação primária ainda preservadas e unidades de conservação são insuficientes para garantir a conservação de espécies. Cultivos de florestas homogêneas passaram a ser considerados como possíveis habitats alternativos para espécies florestais e podem contribuir para a conservação da biodiversidade. O Brasil é o país com maior área ocupada com plantio de eucalipto e essa vem crescendo nos últimos anos. Identificar quais fatores influenciam a diversidade da biota nos plantios é importante para a conservação de espécies. O objetivo do presente estudo foi conhecer a composição florística do sub-bosque de plantios de Eucalyptus saligna Sm. e avaliar se o tipo de solo e a idade do plantio influenciam a riqueza e a composiçao da vegetação que ocupa esse ambiente. Para isso foi realizado o levantamento das espécies vegetais que ocorrem nos cultivos localizados em solo argiloso e arenoso, nos quais os indivíduos de E. saligna tinham três e sete anos. Foram avaliados como fatores ambientais características do solo, produção de serapilheira pelas árvores do plantio, abertura do dossel, uso do solo no entorno do cultivo e tamanho do plantio. No total, foram encontradas 218 espécies vegetais. As análises estatísticas foram realizadas apenas com as espécies que estavam presentes em pelo menos duas unidades amostrais. Plantios em solo argiloso apresentaram maior riqueza que no solo arenoso e houve diferença significativa na composição de espécies entre os dois tipos de solo. Grande parte dos fatores ambientais mensurados também foram diferentes entre os solos. Não foi possível verificar diferenças na riqueza, na composição de espécies e nos fatores ambientais entre os plantios de diferentes idades. O tipo de solo pode ser um fator mais limitante do que a idade da floresta plantada para determinar a riqueza e composição das espécies que compõem o sub-bosque dos plantios. Embora a riqueza de espécies no solo arenoso seja menor, esse também é importante para a conservação, porque abriga espécies adaptadas à menor disponibilidade de recursos, que não ocorrem em outros ambientes. O grande número de espécies encontrado no sub-bosque destes plantios indica que eles podem auxiliar na conservação de espécies nativas, mas esse potencial deve ser melhor investigado. São recomendados estudos de outros fatores, como a biologia de espécies importantes ecológica e econômicamente, interações entre animais e plantas e diferentes estratégias de manejo, para investigar de que forma eles afetam a biodiversidade e como eles podem ajudar a avaliar e aumentar o potencial de conservação das florestas industriais. / Landscape change and habitat fragmentaiton are recognized as threats to global biodiversity.Areas with remaining primary vegetation and protected areas are insufficient to ensure species conservation. Forest monocultures are potencial alternative habitats for native species and may contribute to the conservation of biodiversity. Brazil is the country with the largest area occupied with eucalypt plantations, this area is also growing in the last years. Identifying which factors influence the biodiversity on plantations is important to species conservation. The objective of this study was to know the understory species composition in Eucalyptus saligna Sm. plantations and to evaluate the influence of soil type and stand age on species richness and species composition. Surveys of vegetation were performed in stands on clay and sandy soils where the eucalypt trees were three and seven years old. Other soil characteristics, litter production by stand trees, canopy open and land use surrounding stands were evaluated as environmental factors. 218 plant species were found in plantations understory. The stands on clay soil were richer than those on sandy soil. Most of the environmental factors evaluated were also different among stands on different soils type. It was not possible to verify differences on species richness and species composition nor environmental factors between stand ages. Soil type could be a more limiting factor than forest age to determine species richness and species composition on plantations understory. Sandy soils are poorer in species, but they are also important to conservation, since species that happen on sandy soils are adapted to low resources availability and do not occur at other locations. The large number of native species founded in eucalypts plantation understory indicates that these plantations may assist some native species conservation. Nevertheless, further research is needed to understand the conservation potential from eucalypt plantations. It is recommended other studies to be done for a better comprehension and to increase the importance of plantation forests to conservation, mainly studies about biology of key species, interactions between animals and plants and the effect of different management options.

A modificação da paisagem e a fragmentação de habitats são consideradas ameaças à biodiversidade mundial. Áreas cobertas por vegetação primária ainda preservadas e unidades de conservação são insuficientes para garantir a conservação de espécies. Cultivos de florestas homogêneas passaram a ser considerados como possíveis habitats alternativos para espécies florestais e podem contribuir para a conservação da biodiversidade. O Brasil é o país com maior área ocupada com plantio de eucalipto e essa vem crescendo nos últimos anos. Identificar quais fatores influenciam a diversidade da biota nos plantios é importante para a conservação de espécies. O objetivo do presente estudo foi conhecer a composição florística do sub-bosque de plantios de Eucalyptus saligna Sm. e avaliar se o tipo de solo e a idade do plantio influenciam a riqueza e a composiçao da vegetação que ocupa esse ambiente. Para isso foi realizado o levantamento das espécies vegetais que ocorrem nos cultivos localizados em solo argiloso e arenoso, nos quais os indivíduos de E. saligna tinham três e sete anos. Foram avaliados como fatores ambientais características do solo, produção de serapilheira pelas árvores do plantio, abertura do dossel, uso do solo no entorno do cultivo e tamanho do plantio. No total, foram encontradas 218 espécies vegetais. As análises estatísticas foram realizadas apenas com as espécies que estavam presentes em pelo menos duas unidades amostrais. Plantios em solo argiloso apresentaram maior riqueza que no solo arenoso e houve diferença significativa na composição de espécies entre os dois tipos de solo. Grande parte dos fatores ambientais mensurados também foram diferentes entre os solos. Não foi possível verificar diferenças na riqueza, na composição de espécies e nos fatores ambientais entre os plantios de diferentes idades. O tipo de solo pode ser um fator mais limitante do que a idade da floresta plantada para determinar a riqueza e composição das espécies que compõem o sub-bosque dos plantios. Embora a riqueza de espécies no solo arenoso seja menor, esse também é importante para a conservação, porque abriga espécies adaptadas à menor disponibilidade de recursos, que não ocorrem em outros ambientes. O grande número de espécies encontrado no sub-bosque destes plantios indica que eles podem auxiliar na conservação de espécies nativas, mas esse potencial deve ser melhor investigado. São recomendados estudos de outros fatores, como a biologia de espécies importantes ecológica e econômicamente, interações entre animais e plantas e diferentes estratégias de manejo, para investigar de que forma eles afetam a biodiversidade e como eles podem ajudar a avaliar e aumentar o potencial de conservação das florestas industriais. / Landscape change and habitat fragmentaiton are recognized as threats to global biodiversity.Areas with remaining primary vegetation and protected areas are insufficient to ensure species conservation. Forest monocultures are potencial alternative habitats for native species and may contribute to the conservation of biodiversity. Brazil is the country with the largest area occupied with eucalypt plantations, this area is also growing in the last years. Identifying which factors influence the biodiversity on plantations is important to species conservation. The objective of this study was to know the understory species composition in Eucalyptus saligna Sm. plantations and to evaluate the influence of soil type and stand age on species richness and species composition. Surveys of vegetation were performed in stands on clay and sandy soils where the eucalypt trees were three and seven years old. Other soil characteristics, litter production by stand trees, canopy open and land use surrounding stands were evaluated as environmental factors. 218 plant species were found in plantations understory. The stands on clay soil were richer than those on sandy soil. Most of the environmental factors evaluated were also different among stands on different soils type. It was not possible to verify differences on species richness and species composition nor environmental factors between stand ages. Soil type could be a more limiting factor than forest age to determine species richness and species composition on plantations understory. Sandy soils are poorer in species, but they are also important to conservation, since species that happen on sandy soils are adapted to low resources availability and do not occur at other locations. The large number of native species founded in eucalypts plantation understory indicates that these plantations may assist some native species conservation. Nevertheless, further research is needed to understand the conservation potential from eucalypt plantations. It is recommended other studies to be done for a better comprehension and to increase the importance of plantation forests to conservation, mainly studies about biology of key species, interactions between animals and plants and the effect of different management options.

<p>The main objectives of this thesis are to study if a topographic wetness index (TWI) could be used as a tool for predicting the spatial distribution of vascular plant species richness in the boreal forest as well as to study congruence in species richness between vascular plants, liverworts, mosses and lichens. A wetness index ln(a/tanβ) based on topography was used to assign a specific TWI-value to every 20 x 20m grid in two 25 km2 boreal forest landscapes (differing in average soil pH) in northern Sweden. Soil pH is known to be influenced by groundwater and to affect plant species richness in other biomes. Therefore, the relationships between plant species richness, TWI and soil pH were also studied. </p><p>The results showed that the majority of the investigated boreal forest landscapes were relatively dry and species-poor, whereas interspersed patches linked to areas with relatively high TWI had species-rich vegetation including the species of the drier parts of the landscape. There was a positive relationship between species richness of vascular plants and the TWI in both landscapes, but varied with average soil pH. TWI explained 30 % and 52 % of the variation in plant species richness in the landscape with lower and higher pH, respectively. The proportion of regionally uncommon plants also increased with TWI. Testing different calculation methods of the TWI resulted in a large variation in correlation strengths between the various TWI-values and different measured variables (species richness of vascular plants, soil pH, groundwater flow and soil moisture). The relationship between plant species richness and TWI could be further improved with some of the calculation methods. </p><p>When studying correlations in species richness using data sets from boreal forest in northern Sweden, strong positive correlations among vascular plants, mosses and liverworts were found, but no significant correlation between macrolichens and any of the other groups. This result could be explained by that the species number of each of the three related groups increases with ambient moisture, whereas the species number of macrolichens is weakly associated with moisture. </p><p>In conclusion, the TWI could become a useful tool in conservation management for identifying areas of special interest prior to field inventories. Since vascular plants can be used as an indicator taxon for species richness of mosses and liverworts, high TWI-values indicate areas of species hotspots of these taxa.</p> / <p>Syftet med avhandlingen är att dels studera om ett topografiskt fuktighetsindex skulle kunna vara användbart för att förutsäga fördelningen av kärlväxters artrikedom i boreal skog, dels att studera om den rumsliga fördelningen av artrikedom hos kärlväxter, blad- och levermossor samt lavar sammanfaller.</p><p>Ett fuktighetsindex, ln(a/tanβ), som bara är baserat på topografi användes för att beräkna ett indexvärde för varje 20 x 20 m grid i två 25 km2 stora boreala skogslandskap (med i medeltal olika mark-pH) i norra Sverige. Det är känt att mark-pH påverkas av grundvatten och att pH i sin tur påverkar artrikedom hos kärlväxter i andra biom. Därför studerades även sambanden mellan kärlväxters artrikedom, mark pH och TWI.</p><p>Resultaten visade att större delen av det studerade boreala landskapet var relativt torrt och artfattigt, medan mindre utspridda områden med höga TWI-värden var artrika på kärlväxter och här växte även arter som återfanns i de torra delarna av skogen. Sambandet mellan artrikedom hos kärlväxter och TWI var positivt i båda landskapen, men påverkades av de olika nivåerna på mark-pH. TWI förklarade 30 % av variationen i artrikedom i området med lägre mark-pH respektive 50 % i området med högre mark-pH. Andelen kärlväxter som klassificeras som icke vanliga i respektive region ökade också med TWI. Med andra beräkningsmetoder för TWI visade det sig att styrkan på korrelationerna mellan TWI och olika uppmätta variabler (artrikedom hos kärlväxter, mark-pH, grundvattennivå och markfuktighet) varierade mycket. Sambandet mellan artrikedom hos kärlväxter och TWI kunde förbättras ytterligare med vissa beräkningsmetoder.</p><p>Då korrelationer i artrikedom studerades användes ett dataset från boreal skog i norra Sverige. Resultaten visade på starka, positiva korrelationer mellan kärlväxter, blad- och levermossor, men inga korrelationer mellan någon av dessa grupper och lavar. Detta kunde förklaras med att artrikedom hos de tre korrelerande organismgrupperna ökar med ökad fuktighet, medan artrikedom hos lavar inte är kopplat till fukt.</p><p>Huvudslutsatsen i avhandlingen är att TWI, som endast är baserad på topograpfiskt data, skulle kunna bli ett värdefullt redskap i naturvårdsplanering för att identifiera särskilt intressanta skogsområden innan man gör fältinventeringar. Eftersom studien visar att kärlväxter kan användas som en indikator grupp för artrikedom hos blad- och levermossor indikerar höga TWI-värden områden med hög artrikedom även vad gäller dessa taxa.</p>

The main objectives of this thesis are to study if a topographic wetness index (TWI) could be used as a tool for predicting the spatial distribution of vascular plant species richness in the boreal forest as well as to study congruence in species richness between vascular plants, liverworts, mosses and lichens. A wetness index ln(a/tanβ) based on topography was used to assign a specific TWI-value to every 20 x 20m grid in two 25 km2 boreal forest landscapes (differing in average soil pH) in northern Sweden. Soil pH is known to be influenced by groundwater and to affect plant species richness in other biomes. Therefore, the relationships between plant species richness, TWI and soil pH were also studied. The results showed that the majority of the investigated boreal forest landscapes were relatively dry and species-poor, whereas interspersed patches linked to areas with relatively high TWI had species-rich vegetation including the species of the drier parts of the landscape. There was a positive relationship between species richness of vascular plants and the TWI in both landscapes, but varied with average soil pH. TWI explained 30 % and 52 % of the variation in plant species richness in the landscape with lower and higher pH, respectively. The proportion of regionally uncommon plants also increased with TWI. Testing different calculation methods of the TWI resulted in a large variation in correlation strengths between the various TWI-values and different measured variables (species richness of vascular plants, soil pH, groundwater flow and soil moisture). The relationship between plant species richness and TWI could be further improved with some of the calculation methods. When studying correlations in species richness using data sets from boreal forest in northern Sweden, strong positive correlations among vascular plants, mosses and liverworts were found, but no significant correlation between macrolichens and any of the other groups. This result could be explained by that the species number of each of the three related groups increases with ambient moisture, whereas the species number of macrolichens is weakly associated with moisture. In conclusion, the TWI could become a useful tool in conservation management for identifying areas of special interest prior to field inventories. Since vascular plants can be used as an indicator taxon for species richness of mosses and liverworts, high TWI-values indicate areas of species hotspots of these taxa. / Syftet med avhandlingen är att dels studera om ett topografiskt fuktighetsindex skulle kunna vara användbart för att förutsäga fördelningen av kärlväxters artrikedom i boreal skog, dels att studera om den rumsliga fördelningen av artrikedom hos kärlväxter, blad- och levermossor samt lavar sammanfaller. Ett fuktighetsindex, ln(a/tanβ), som bara är baserat på topografi användes för att beräkna ett indexvärde för varje 20 x 20 m grid i två 25 km2 stora boreala skogslandskap (med i medeltal olika mark-pH) i norra Sverige. Det är känt att mark-pH påverkas av grundvatten och att pH i sin tur påverkar artrikedom hos kärlväxter i andra biom. Därför studerades även sambanden mellan kärlväxters artrikedom, mark pH och TWI. Resultaten visade att större delen av det studerade boreala landskapet var relativt torrt och artfattigt, medan mindre utspridda områden med höga TWI-värden var artrika på kärlväxter och här växte även arter som återfanns i de torra delarna av skogen. Sambandet mellan artrikedom hos kärlväxter och TWI var positivt i båda landskapen, men påverkades av de olika nivåerna på mark-pH. TWI förklarade 30 % av variationen i artrikedom i området med lägre mark-pH respektive 50 % i området med högre mark-pH. Andelen kärlväxter som klassificeras som icke vanliga i respektive region ökade också med TWI. Med andra beräkningsmetoder för TWI visade det sig att styrkan på korrelationerna mellan TWI och olika uppmätta variabler (artrikedom hos kärlväxter, mark-pH, grundvattennivå och markfuktighet) varierade mycket. Sambandet mellan artrikedom hos kärlväxter och TWI kunde förbättras ytterligare med vissa beräkningsmetoder. Då korrelationer i artrikedom studerades användes ett dataset från boreal skog i norra Sverige. Resultaten visade på starka, positiva korrelationer mellan kärlväxter, blad- och levermossor, men inga korrelationer mellan någon av dessa grupper och lavar. Detta kunde förklaras med att artrikedom hos de tre korrelerande organismgrupperna ökar med ökad fuktighet, medan artrikedom hos lavar inte är kopplat till fukt. Huvudslutsatsen i avhandlingen är att TWI, som endast är baserad på topograpfiskt data, skulle kunna bli ett värdefullt redskap i naturvårdsplanering för att identifiera särskilt intressanta skogsområden innan man gör fältinventeringar. Eftersom studien visar att kärlväxter kan användas som en indikator grupp för artrikedom hos blad- och levermossor indikerar höga TWI-värden områden med hög artrikedom även vad gäller dessa taxa.