Prosopis, an Alien among the Sacred Trees of South India

The problematic of invasive species in an alien environment has aroused the attention of scientists all over the world for quite some time. One of the exotic tree species that has provoked special attention in the tropical drylands is Prosopis juliflora. Originating in South America, prosopis (hereafter referred to as prosopis) has been introduced in the hot and semi-arid zones of the world particularly to provide fuelwood, to stabilize sand dunes and to combat desertification. The tree has become an essential source for fuelwood and a provider of several other products and services in areas where it has become established. However, despite the numerous benefits the tree provides to rural people, in several regions prosopis has become a noxious weed with a negative impact on the environment and to the economy of farmers and landowners. In India, prosopis was introduced in Andhra Pradesh in 1877. The tree was then proclaimed as the precious child of the plant world by scientists and local people alike. The purpose of this study was to investigate the overall impact of prosopis on local rural livelihoods in the drylands of South India. Of particular interest was the examination of the different usages of the tree, especially as fuelwood, and people s perceptions of it. Furthermore, the study examined the negative impacts of the uncontrolled invasion of prosopis on croplands, and its occupation of the banks of irrigation canals and other water sources. As another central theme, this study analysed the Hindu classification system for nature and for trees in particular. In India, several tree species are regarded as sacred. This study examined the position of the exotic prosopis among sacred trees, such as the bodhi, banyan and neem trees. The principle method for collecting the field data was by using individual and thematic group interviews. These interviews were semi-structured with open ended questions. Moreover, unstructured interviews as well as general observations provided complementary information. The data were gathered during two fieldwork periods in the states of Andhra Pradesh and Tamil Nadu, in South India. The results confirmed that prosopis both provides benefits and causes hazards to different stakeholders. Farmers and agriculturalists suffer economic losses in areas where prosopis has invaded crop fields and competes with other plants for water and nutrients. On the other hand, for a significant number of poor rural people, prosopis has become an important source of livelihood benefits. This tree, which grows on government wastelands, is commonly a free resource for all and has thus become a major local source of fuelwood. It also provides several other goods and services and cash income that contributes to improve livelihoods in rural communities. Prosopis ranked lowest in the tree classificatioin system of the Hindus of South India. Although it is appreciated for many benefits it provides for poor people, it has remained an outsider compared with the indigenous tree species. On the other hand, the most sacred trees, such as the bodhi or the banyan, are completely excluded from extraction and it is seen as a sacrilege to even cut branches from any of these trees. An unexpected finding was that, in a few cases, prosopis had also been elevated to the status of a sacred tree. Goods and services from prosopis are not utilized in the most beneficial way. Silvicultural management practices are suggested that would provide additional income and employment opportunities. Interventions are recommended to control further invasion of the tree that might cause serious negative effects in the future. For Hindus, the sacred always ranks highest, even above economic gain. The conservation of sacred groves and sacred trees is a tradition that has its roots in ancient history. These socio-religious practices need to be respected and continued. Successful management of tree and forest resources depends on the willingness of the local people to manage their natural resources, and this willingness exists and has always existed in South India. Keywords: South India, drylands, livelihood, fuelwood, invasive, resource, silviculture.

Urban ecosystem services at the plant-soil interface

Continuing urbanization is a crucial driver of land transformation, having widespread impacts on virtually all ecosystems. Terrestrial ecosystems, including disturbed ones, are dependent on soils, which provide a multitude of ecosystem services. As soils are always directly and/or indirectly impacted through land transformation, land cover change causes soil change. Knowledge of ecosystem properties and functions in soils is increasing in importance as humans continue to concentrate into already densely-populated areas. Urban soils often have hampered functioning due to various disturbances resulting from human activity. Innovative solutions are needed to bring the lacking ecosystem services and quality of life to these urban environments. For instance, the ecosystem services of the urban green infrastructure may be substantially improved through knowledge of their functional properties. In the research forming this thesis, the impacts of four plant species (Picea abies, Calluna vulgaris, Lotus corniculatus and Holcus lanatus) on belowground biota and regulatory ecosystem services were investigated in two different urban soil types. The retention of inorganic nitrogen and phosphorus in the plant-soil system, decomposition of plant litter, primary production, and the degradation of polycyclic aromatic hydrocarbons (PAHs) were examined in the field and under laboratory conditions. The main objective of the research was to determine whether the different plant species (representing traits with varying litter decomposability) will give rise to dissimilar urban belowground communities with differing ecological functions. Microbial activity as well as the abundance of nematodes and enchytraeid worm biomass was highest below the legume L. corniculatus. L. corniculatus and the grass H. lanatus, producing labile or intermediate quality litter, enhanced the proportion of bacteria in the soil rhizosphere, while the recalcitrant litter-producing shrub C. vulgaris and the conifer P. abies stimulated the growth of fungi. The loss of nitrogen from the plant-soil system was small for H. lanatus and the combination of C. vulgaris + P. abies, irrespective of their energy channel composition. These presumably nitrogen-conservative plant species effectively diminished the leaching losses from the plant-soil systems with all the plant traits present. The laboratory experiment revealed a difference in N allocation between the plant traits: C. vulgaris and P. abies sequestered significantly more N in aboveground shoots in comparison to L. corniculatus and H. Lanatus. Plant rhizosphere effects were less clear for phosphorus retention, litter decomposition and the degradation of PAH compounds. This may be due to the relatively short experimental durations, as the maturation of the plant-soil system is likely to take a considerably longer time. The empirical studies of this thesis demonstrated that the soil communities rapidly reflect changes in plant coverage, and this has consequences for the functionality of soils. The energy channel composition of soils can be manipulated through plants, which was also supported by the results of the separate meta-analysis conducted in this thesis. However, further research is needed to understand the linkages between the biological community properties and ecosystem services in strongly human-modified systems.

Plant communities of field margins : the effects of management and environmental factors on species composition and diversity

Agri-environmental schemes have so far resulted in only minor positive implications for the biodiversity of agricultural environments, in contrast to what has been expected. Land-use intensification has decreased landscape heterogeneity and the amount of semi-natural habitats. Field margins are uncultivated areas of permanent vegetation located adjacent to fields. Since the number of these habitats is high, investing in their quality may result in more diverse agricultural landscapes. Field margins can be considered as multifunctional habitats providing agronomic, environmental and wildlife services. This thesis aimed at examining the plant communities of different types of field margin habitats and the factors affecting their species diversity and composition. The importance of edaphic, spatial and management factors was studied on regional, landscape and habitat scales. Vegetation surveys were conducted on regional and landscape scales and a field experiment on cutting management was conducted on a habitat scale. In field margin plant communities, species appeared to be indicators of high or intermediate soil fertility and moist soil conditions. The plant species diversity found was rather low, compared with most species-rich agricultural habitats in Finland, such as dry meadows. Among regions, land-use history, main production line, natural species and human induced distribution, climate and edaphic factors were elements inducing differences in species composition. The lowest regional species diversity of field margins was related to intensive and long-term cereal production. Management by cutting and removal or grazing had a positive effect on plant species diversity. The positive effect of cutting and removal on species richness was also dependent on the adjacent source of colonizing species. Therefore, in species-poor habitats and landscapes, establishment of margins with diverse seed mixtures can be recommended for enhancing the development of species richness. However, seed mixtures should include only native species preferably local origin. Management by cutting once a year for 5 years did not result in a decline in dominance of a harmful weed species, Elymus repens, showing that E. repens probably needs cutting more frequently than once per year. Agri-environmental schemes should include long-term contracts with farmers for the establishment, and management by cutting and removal or grazing, of field margins that are several metres wide. In such schemes, the timing and frequency of management should be planned so as not to harm other taxa, such as the insects and birds that are dependent on these habitats. All accidental herbicide drifts to field margins should be avoided when spraying the cultivated area to minimize the negative effects of sprayings on vegetation. The harmful effects of herbicides can be avoided by organic farming methods.

Population genetics of the invasive plant species Impatiens glandulifera in Southern Finland

Biological invasions affect biodiversity worldwide, and, consequently, the invaded ecosystems may suffer from significant losses in economic and cultural values. Impatiens glandulifera Royle (Balsaminaceae) is an invasive annual herb, native to the western Himalayas and introduced into Europe in the 19th century as a garden ornamental plant. The massive invasion of I. glandulifera is due to its high reproductive output, rapid growth and its ability to outcompete native species. In Finland, the first observations regarding the presence of I. glandulifera date from the year 1947, and today it is considered a serious problem in riparian habitats. The aim of this master’s thesis research is to reveal the population genetic structure of I. glandulifera in Finland and to find out whether there have been one or multiple invasions in Finland. The study focuses on investigating the origin of I. glandulifera in Southern Finland, by comparing plant samples from the Helsinki region with those from its native region and other regions of invasion. Samples from four populations in Helsinki and from the United Kingdom, Canada, India and Pakistan were collected and genotyped using 11 microsatellite markers. The genetic analyses were evaluated using the programs Arlequin and Structure. The results of the genetic analyses suggested that I. glandulifera has been introduced to Finland more than once. Multiple introductions are supported by the higher level of genetic diversity detected within and among Finnish populations than would be expected for a single introduction. Results of the Bayesian Structure analysis divided the four Finnish populations into four clusters. This geographical structure was further supported by pairwise Fst values among populations. The causes and potential consequences of such multiple introductions of I. glandulifera in Finland and further perspectives are discussed.

Diversitet och tillväxtfrämjande egenskaper hos Stenotrophomonas-endofyter isolerade från Calliandra calothyrsus Meisn. rotknölar

The bacterial genus Stenotrophomonas comprises 12 species. They are widely found throughout the environment and particularly S. maltophilia, S. rhizophila and S. pavanii are closely associated with plants. Strains of the most common Stenotrophomonas species, S. maltophilia, promote plant growth and health, degrade natural and man-made pollutants and produce biomolecules of biotechnological and economical value. Many S. maltophilia –strains are also multidrug resistant and can act as opportunistic human pathogens. During an INCO-project (1998-2002) rhizobia were collected from root nodules of the tropical leguminous tree Calliandra calothyrsus Meisn. from several countries in Central America, Africa and New Caledonia. The strains were identified by the N2-group (Helsinki university) and some strains turned out to be members of the genus Stenotrophomonas. Several Stenotrophomonas strains induced white tumor- or nodule-like structures on Calliandra?s roots in plant experiments. The strains could, besides from root nodules, also be isolated from surface sterilized roots and stems. The purpose of my work was to investigate if the Stenotrophomonas strains i) belong to a new Stenotrophomonas species, ii) have the same origin, iii) if there are other differences than colony morphology between phase variations of the same strain, iv) have plant growth-promoting (PGP) activity or other advantageous effects on plants, and v) like rhizobia have ability to induce root nodule formation. The genetic diversity and clustering of the Stenotrophomonas strains were analyzed with AFLP fingerprinting to get indications about their geographical origin. Differences in enzymatic properties and ability to use different carbon and energy sources were tested between the two phases of each strain with commercial API tests for bacterial identification. The ability to infect root hairs and induce root nodule formation was investigated both using plant tests with the host plant Calliandra and PCR amplification of nodA and nodC genes for nodulation. The PGP activity of the strains was tested in vitro mainly with plate methods. The impact on growth, nitrogen content and nodulation in vivo was investigated through greenhouse experiments with the legumes Phaseolus vulgaris and Galega orientalis. Both the genetic and phenotypic diversity among the Stenotrophomonas strains was small, which proposes that they have the same origin. The strains brought about changes on the root hairs of Calliandra and they also increased the amount of root hairs. However, no root nodules were detected. The strains produced IAA, protease and lipase in vitro. They also showed plant a growth-promoting effect on G. orientalis, both alone and together with R. galegae HAMBI 540, and also activated nodulation among efficient rhizobia on P. vulgaris in greenhouse. It requires further research to get a better picture about the mechanisms behind the positive effects. The results in this thesis, however, confirm earlier studies concerning Stenotrophomonas positive impact on plants.

Litter quality and its response to water level drawdown in boreal peatlands at plant species and community level

Changes in the structure of plant communities may have much more impact on ecosystem carbon (C) cycling than any phenotypic responses to environmental changes. We studied these impacts via the response of plant litter quality, at the level of species and community, to persistent water-level (WL) drawdown in peatlands. We studied three sites with different nutrient regimes, and water-level manipulations at two time scales. The parameters used to characterize litter quality included extractable substances, cellulose, holocellulose, composition of hemicellulose (neutral sugars, uronic acids), Klason lignin, CuO oxidation phenolic products, and concentrations of C and several nutrients. The litters formed four chemically distinct groups: non-graminoid foliar litters, graminoids, mosses and woody litters. Direct effects of WL drawdown on litter quality at the species level were overruled by indirect effects via changes in litter type composition. The pristine conditions were characterized by Sphagnum moss and graminoid litters. Short-term (years) responses of the litter inputs to WL drawdown were small. In longterm (decades), total litter inputs increased, due to increased tree litter inputs. Simultaneously, the litter type composition and its chemical quality at the community level greatly changed. The changes that we documented will strongly affect soil properties and C cycle of peatlands.

Does the age of fine root carbon indicate the age of fine roots in boreal forests?

To test the reliability of the radiocarbon method for determining root age, we analyzed fine roots (originating from the years 1985 to 1993) from ingrowth cores with known maximum root age (1 to 6 years old). For this purpose, three Scots pine (Pinus sylvestris L.) stands were selected from boreal forests in Finland. We analyzed root 14C age by the radiocarbon method and compared it with the above-mentioned known maximum fine root age. In general, ages determined by the two methods (root 14C age and ingrowth core root maximum age) were in agreement with each other for roots of small diameter (<0.5mm). By contrast, in most of the samples of fine roots of larger diameter (1.5-2mm), the 14C age of root samples of 1987-89 exceeded the ingrowth core root maximum age by 1-10 years. This shows that these roots had received a large amount of older stored carbon from unknown sources in addition to atmospheric CO2 directly from photosynthesis. We conclude that the 14C signature of fine roots, especially those of larger diameter, may not always be indicative of root age, and that further studies are needed concerning the extent of possible root uptake of older carbon and its residence time in roots. Keywords: fine root age, Pinus sylvestris, radiocarbon, root carbon, ingrowth cores, tree ring

Jakojuuriviljelyn vaikutus kasvihuonekurkun (Cucumis sativus L.) kasvuun ja kehitykseen

Kasvit ottavat vettä parhaiten kasteluravinneliuoksesta, jonka ravinnepitoisuus on pieni. Intensiivisessä kasvihuonetuotannossa käytetään silti kastelulannoituksessa usein korkeita ravinnepitoisuuksia ravinnepuutosten ja satotappioiden välttämiseksi. Jakojuuriviljelyssä kasvin juuriston annetaan kasvaa kahteen erilliseen kasvualustaosioon. Tällöin toiselle puolelle annetaan johtokyvyltään väkevää ja toiselle puolelle laimeaa ravinneliuosta. Erityisesti kasvihuonekurkun, joka on herkkä kasvualustan suolaisuuden aiheuttamille vedensaantiongelmille, on todettu hyötyvän tästä tekniikasta, mikä näkyy kasvaneina satoina. Tämän MTT Piikkiössä toteutetun kasvihuonekurkun jakojuuriviljelytutkimuksen tavoitteena oli tarkentaa tekniikkaa erityisesti kasteluliuosten johtokyvyn osalta. Yhtenäisjuuriviljelyn ja perinteisen jakojuuriviljelyn lisäksi kokeessa oli kaksi jakojuuriviljelykäsittelyä, joissa ravinneliuosväkevyyksiä vaihdettiin väliajoin juuriston toimintakyvyn parantamiseksi. Erillisessä osakokeessa tutkittiin erilaisten johtokyky-yhdistelmien vaikutusta kasvihuonekurkun vegetatiiviseen kasvuun maanpäällisten ja -alaisten kasvinosien välillä sekä juurten morfologiaan ja anatomiaan. Tulokset osoittivat, että jakojuuriviljely lisäsi kasvihuonekurkun sadontuottoa jopa 16 %, mutta ei vaikuttanut koko viljelykauden veden tai ravinteiden ottoon. Yhtenäisjuuriviljelyssä muodostui eniten piikkikärkisiä hedelmiä, mikä viittaa vedensaantiongelmiin haihdutustarpeen ollessa suurin. Viljelytekniikalla ei ollut vaikutusta kasvien vegetatiiviseen kasvuun tai kasvuston rakenteeseen. Lehtiruodeista tehdyt nitraatti- ja kaliummittaukset osoittivat, ettei kasteluliuosten ravinnepitoisuuksilla ollut vaikutusta juurten ravinteiden ottoon. Erilaisilla johtokyky-yhdistelmillä oli huomattavampi vaikutus kasvihuonekurkun juurten painoon kuin verson painoon tai varren pituuskasvuun. Lehtiruotianalyysit viittasivat ravinteiden erilaiseen allokointiin eri johtokyky-yhdistelmissä. Korkeiden johtokykyjen aiheuttama osmoottinen stressi johti muutoksiin juurten morfologiassa ja anatomiassa. Tulosten perusteella jakojuuriviljely paransi kehittyvien hedelmien kohdevahvuutta suhteessa muihin kohteisiin vaikuttamatta vegetatiiviseen kasvuun. Kun laimean ja väkevän ravinneliuoksen puolia vaihdettiin, juuristo otti joustavasti vettä ja ravinteita olosuhteiden määräämästä edullisemmasta johtokyvystä, jolloin kasvihuonekurkun viljelyssä saavutettiin merkittävä satoetu. Juuriston jakaminen vaikuttanee kasvien hormoniaineenvaihduntaan ja voi heikentää juuriston kasvua heikentämättä sen toimintakykyä, jolloin yhteyttämistuotteita kohdennetaan tehokkaammin maanpäällisten osien kasvuun.