PLANT COVE R DIVERSITY OF TECHNOZEMES OF RECLAMATION LAND AT THE NIKOPOL MANGANESE ORE BASIN

The study of the disturbed natural complexes evolution processes is important for the development of the most effective and rational methods of reclamation. The restoration of vegetation is one of the most informative components of ecosystems. Plant complexes, which have been formed during self-establishment, are an integral indicator of the dumps suitability degree for biological reclamation

Soil nematode communities in grasslands

This thesis summarizes the results of five studies investigating the effect of plant species on soil nematode communities in grasslands. Nematodes (roundworms) are ubiquitous members of the soil fauna and have been much used as indicators of soil conditions. Plants have the ability to affect soil organisms through structural modification of the soil habitat and through the quantity and quality of organic matter that is returned to soil, in the form of plant litter and root exudates. The influence of grassland plant species on the soil nematode fauna was investigated in an experimental grassland, a glasshouse experiment and in a semi-natural grassland. Monocultures of 12 grassland plant species belonging to three plant functional groups, viz. grasses, legumes and non-leguminous forbs, were investigated in the field experiment and a subset of these in the other two systems. Plant species effects were common, for example, plant feeding and bacterial feeding nematodes responded positively to legumes and grasses, while forbs enhanced fungal feeding nematodes. Plant species identity appeared to be much more important than plant functional group for the nematode fauna. The effects of plants were quite consistent between field and glasshouse experiments. The influence of plant species diversity and functional diversity on the nematode fauna was investigated in the experimental grassland. Plant species composition proved to be more important for soil nematode communities than any of the plant diversity measures, but the hypothesis that species or functional diversity of plants affect nematode diversity or composition could not be rejected. My results also suggest that plant species identity may be an important determinant of spatial structure in natural grasslands. There was a succession of the nematode fauna during the eight years after establishment of the experimental grassland, especially indicated by the increase in maturity index of the nematode fauna. The results highlight the need for long-term experiments to reveal successional trends in soil nematode communities after cessation of agriculture. The increase of plant feeders with time, the slow colonization rate and the enhanced abundance of fungal feeders in soil under forbs have implications for nature restoration of former agricultural land

Damping-off within natural and disturbed kwongan plant communities

Fungal and oomycete damping-off pathogens kill pre- and post-emergent seedlings and can regulate the abundance of plant species to help maintain diversity in natural ecosystems. However, damping-off pathogens may be detrimental to post-mining ecological restoration, a key hurdle in the process is the loss of pre- and post-emergent seedlings. Recently, several putatively native Phytophthora species, soil-borne oomycete plant pathogens, have been recovered from hyper-diverse kwongan vegetation in southwest Australia and may be damping-off pathogens. Damping-off pathogens may contribute to maintaining the diversity of natural kwongan plant communities and reduce seedling establishment within ecological restoration. Four experiments were designed to identify the distribution and role of Phytophthora and other potential damping-off oomycetes in natural and restored kwongan plant communities. Putatively native Phytophthora arenaria, introduced P. cinnamomi and Pythium irregulare were identified as damping-off pathogens with wide host ranges of native kwongan plant species through a glasshouse pathogenicity trial. Fungicide seed coat treatments improved seedling emergence for five of the 14 plant species studied in ecological restoration field trials, identifying low to moderate levels of pre-emergent damping-off caused by oomycetes and fungi. Natural kwongan soils collected from different plant species affected seedling emergence and survival in a glasshouse experiment. Damping-off caused conspecific negative plant-soil feedback for Jacksonia floribunda and Xanthorrhoea sp. Lesueur, a process that contributes to the maintenance of diversity in plant communities. Although, the presence and abundance of oomycetes detected using metabarcoding from the same natural kwongan soils were not associated with reduced seedling emergence or survival. In a regional metabarcoding survey of natural kwongan plant communities, the Phytophthora species richness and abundance were far lower than previously hypothesised due to the elimination of sources of sampling biases. Plant species and host age were strong drivers of the oomycete communities detected at a local scale using metabarcoding. These studies provided an insight into the distribution of important plant pathogens in a species rich Mediterranean shrubland and identified damping-off pathogens could be a mechanism contributing to maintaining the diversity of natural kwongan plant communities and low seedling establishment in ecological restoration

Animal Ecosystem Engineers Modulate the Diversity-Invasibility Relationship

Invasions of natural communities by non-indigenous species are currently rated as one of the most important global-scale threats to biodiversity. Biodiversity itself is known to reduce invasions and increase stability. Disturbances by ecosystem engineers affect the distribution, establishment, and abundance of species but this has been ignored in studies on diversity-invasibility relationships.We determined natural plant invasion into 46 plots varying in the number of plant species (1, 4, and 16) and plant functional groups (1, 2, 3, and 4) for three years beginning two years after the establishment of the Jena Experiment. We sampled subplots where earthworms were artificially added and others where earthworm abundance was reduced. We also performed a seed-dummy experiment to investigate the role of earthworms as secondary seed dispersers along a plant diversity gradient. Horizontal dispersal and burial of seed dummies were significantly reduced in subplots where earthworms were reduced in abundance. Seed dispersal by earthworms decreased with increasing plant species richness and presence of grasses but increased in presence of small herbs. These results suggest that dense vegetation inhibits the surface activity of earthworms. Further, there was a positive relationship between the number of earthworms and the number and diversity of invasive plants. Hence, earthworms decreased the stability of grassland communities against plant invasion.Invasibility decreased and stability increased with increasing plant diversity and, most remarkably, earthworms modulated the diversity-invasibility relationship. While the impacts of earthworms were unimportant in low diverse (low earthworm densities) and high diverse (high floral structural complexity) plant communities, earthworms decreased the stability of intermediate diverse plant communities against plant invasion. Overall, the results document that fundamental processes in plant communities like plant seed burial and invader establishment are modulated by soil fauna calling for closer cooperation between soil animal and plant ecologists

Fragmented areas due to agricultural activity: native vegetation dynamics at crop interface (Montecaseros, Mendoza, Argentina)

Plant communities fragmented by agricultural activities were analyzed in a 250-ha area in eastern plains of Montecaseros, Gral. San Martín Department, Mendoza, Argentina. A phytosociological method assessed different sites along a gradient of human intervention, from natural environments with no evidence of altered native vegetation to maximum farming modification, also including cleared and abandoned fields. Soil analyses supplemented the characterization of six plant communities. A scrubland physiognomy dominates the area, with species of the genera Larrea, Atriplex and Lycium. Tillage and crop abandonment can alter natural factors involved in soil formation, causing deterioration and exerting selective pressure on species colonizing these degraded environments. Evaluating natural vegetation before land clearing for agriculture is essential to assess, through species that indicate environmental conditions, edaphic limitations hindering crop establishment and affecting productivity. The conservation of natural communities on private lands destined for agriculture is valued. Highlights: This study aimed to characterize plant communities in natural and intervened environments, in a representative area of the fragmentation processes caused by agriculture in the Monte Province (Mendoza, Argentina). Plant biodiversity plays a strategic role in ecosystemic provision of goods and services necessary to human health and well-being. Cultivable land is a vulnerable and scarce resource, particularly in drylands, where ecosystems have low capacity for natural regeneration. Tillage and crop abandonment can alter natural factors involved in soil formation, causing deterioration and exerting selective pressure on species colonizing these degraded environments. In agricultural land, clearing can give rise to a mosaic of landscapes: productive crops merge with abandoned crops and fragments of natural fields. Evaluating natural vegetation before land clearing for agriculture is essential to assess, through species that indicate environmental conditions, edaphic limitations hindering crop establishment and affecting productivity. Studies of vegetation dynamism in private lands contribute to plan and implement sustainable land management, tending to recover and conserve biodiversity in degraded soils, considering all associated ecosystem services.Plant communities fragmented by agricultural activities were analyzed in a 250-ha area in eastern plains of Montecaseros, Gral. San Martín Department, Mendoza, Argentina. A phytosociological method assessed different sites along a gradient of human intervention, from natural environments with no evidence of altered native vegetation to maximum farming modification, also including cleared and abandoned fields. Soil analyses supplemented the characterization of six plant communities. A scrubland physiognomy dominates the area, with species of the genera Larrea, Atriplex and Lycium. Tillage and crop abandonment can alter natural factors involved in soil formation, causing deterioration and exerting selective pressure on species colonizing these degraded environments. Evaluating natural vegetation before land clearing for agriculture is essential to assess, through species that indicate environmental conditions, edaphic limitations hindering crop establishment and affecting productivity. The conservation of natural communities on private lands destined for agriculture is valued. Highlights: This study aimed to characterize plant communities in natural and intervened environments, in a representative area of the fragmentation processes caused by agriculture in the Monte Province (Mendoza, Argentina). Plant biodiversity plays a strategic role in ecosystemic provision of goods and services necessary to human health and well-being. Cultivable land is a vulnerable and scarce resource, particularly in drylands, where ecosystems have low capacity for natural regeneration. Tillage and crop abandonment can alter natural factors involved in soil formation, causing deterioration and exerting selective pressure on species colonizing these degraded environments. In agricultural land, clearing can give rise to a mosaic of landscapes: productive crops merge with abandoned crops and fragments of natural fields. Evaluating natural vegetation before land clearing for agriculture is essential to assess, through species that indicate environmental conditions, edaphic limitations hindering crop establishment and affecting productivity. Studies of vegetation dynamism in private lands contribute to plan and implement sustainable land management, tending to recover and conserve biodiversity in degraded soils, considering all associated ecosystem services.

Distribution and natural establishment of Eucalyptus globulus in the Iberian Peninsula: insights into processes affecting plant establishment

Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia. Universidade de LisboaEucalypt plantations expanded across many countries and became subject to controversy, particularly about their ecological impacts and invasive potential. The same is true in the Iberian Peninsula (Iberia) regarding Eucalyptus globulus Labill. This thesis is composed by six studies (chapters) tackling poorly explored aspects in these domains, with the following objectives: a) to evaluate potential future dynamics of E. globulus plantations in Iberia according to different climate change scenarios and possible conflicts with high biodiversity areas (Chapter 1); b) to explore the influence of different factors on the natural establishment of E. globulus (Chapters 2-5); c) to perform a review of the literature investigating the natural establishment of eucalypt species (Chapter 6). In Iberia, under both climatic scenarios, the suitable range of E. globulus plantations is expected to shrink and conflicts with high biodiversity areas may aggravate (Chapter 1). A countrywide survey in Portugal to estimate E. globulus recruitment, using Google Street View, showed that recruitment is mostly influenced by climatic variables (annual precipitation and thermal amplitude) and that Google Street View is a cost-efficient alternative to car surveys (Chapter 2). Field surveys in E. globulus plantations in Central Portugal showed abundant recruitment along plantation edges, influenced by local factors such as soil cover and tree age. Wildlings, mostly adult, are spread up to 76 meters from plantations (Chapter 3). A sowing experiment using E. globulus seeds showed that germination and survival was enhanced after harrowing (Chapter 4). A seed predation experiment revealed that E. globulus seeds are highly attractive but they have escaped in many locations (Chapter 5). The literature review retrieved 37 studies, addressing 61 eucalypt species in seven countries. Key factors influencing eucalypt recruitment include fire, propagule pressure and disturbances (Chapter 6)N/

Relationship between soil properties and natural grassland vegetation on sodic soils

Salinity, pH, climate, and moisture content, along with topographical data were compared between plant associations, to define key factors affecting soil salt accumulation and establishment of natural vegetation. The extreme values found in some associations are explained by the spatial distribution of the studied points

A trait‐based approach to plant species selection to increase functionality of farmland vegetative strips

Farmland vegetative strips are a proven source of support for ecosystem services and are globally used to mitigate effects of agricultural intensification. However, increasing pressures on agricultural land require increases in their functionality, such as supporting multiple ecosystem services concurrently. The plant species sown in a vegetative strip seed mix determine the establishment, plant community, and ecosystem services that are supported. Currently, there is no clearly defined or structured method to select plant species for multifunctional vegetative strips. Plant traits determine how plants support ecosystem services. Also, the establishment and persistence of plant communities is influenced by key internal and external factors. We propose a novel, evidence‐informed method of multifunctional vegetative strip design based on these essential traits and factors. This study had three distinct stages. The first identified plant traits that support water quality protection, pollinators and/or crop pest natural enemies, using existing research evidence. We then identified key factors affecting plant community establishment and persistence. Finally, we applied these standardized methods to design a multifunctional vegetative strip for a specific case study (UK lowland farmland). Key plant traits identified, included floral display size, flower color, nectar content, leaf surface area, leaf trichome density, percentage fine roots, root length, rooting depth, and root density. Key internal and external establishment factors included life history, native status, distribution, established competitive strategy, associated floristic diversity, flowering time and duration, and preferred soil type and pH. In the United Kingdom case study, we used five different plant traits and all of the identified factors to design a seed mix for a multifunctional vegetative strip. We present a transferable method of vegetative strip design that can be adapted for other ecosystem services and climates. It provides landowners and advisors with an evidence‐informed approach to increase field margin functionality while supporting farmland biodiversity

New urban ecological restoration techniques: Testing the short-term effects of adding deciduous leaf litter and plant residue compost on topsoil quality and native herbaceous plant establishment

Urban expansion has led to native habitat destruction. Meanwhile, cities produce large quantities of plant residue wastes. To explore the potential to use plant residues to restore native habitats in cities, this thesis compared the short-term effects of deciduous leaf litter and plant residue compost on topsoil quality and seeded native herbaceous plant establishment. To determine if natural plant colonisation alone can restore native plants, the thesis compared the establishment and ecological characteristic and diversity of naturally colonised plant species on the barren surface of modified and unmodified soil. Following three months of repeated measurements after amendment, compost significantly increased soil moisture, organic matter, extractable NPK, and significantly decreased soil pH and bulk density. The decrease in soil pH due to incorporating compost with higher pH than the receiving soil showed that compost may not restore soil pH in a predictable manner. The average number and median shoot lengths of seeded native plants on compost-amended soil were significantly higher than those on control three months after germination. Compost may therefore be used for purposes such as quick establishment of dense tall native plant cover. Conversely, leaf litter did not significantly change the abovementioned soil properties in the short term. However, the average number of seeded native plants on leaf litter-amended soil three months after germination was significantly higher than control and insignificantly different from that on compost-amended soil. At that time, seeded native plants on leaf litter-soil exhibited stunt growth relative to other treatments. Leaf litter might then be used to establishing slow-growth native lawns for urban native landscaping practices. But this technique requires further refinement. Above barren soils across experimental treatments, exotic weeds consisted mostly of the naturally colonised plants. This means natural plant colonisation may not effectively restore native plants. There was no significant difference in the colonising plant average species richness and diversity across treatments. The steepness of the colonising species’ rank-abundance curves were similar between treatments. Thus, natural plant colonisation on amended or un-amended soil could not lead to the establishment of particular plant species. Due to soil nutrient-enrichment, Canada thistles (Cirsium arvense) occupied a greater proportion of colonised species on compost-treated soil than the most dominant colonised species on other types of soil. Thus, compost amendment of soil may not restore plant communities with high species diversity. Moreover, the average number of the colonising weeds above compost-amended soil was significantly higher than control, while that of weeds above leaf litter-amended soil was significantly lower than control three months after site preparation. At that time, weeds on leaf litter-amended soil were significantly shorter than those on compost-amended soil and control. This means leaf litter could impede exotic weeds while compost had the reverse effect. Compost should only be used to establish native plants if exotic weeds are removed or when the site soil seed bank and adjacent land contain few exotics. While this thesis documented the different short-term effects of plant residue compost and deciduous leaf litter on soil and plants, long-term investigations may find potentially different applications for the different types of plant residues in native plant restoration projects with different purposes. Reusing plant residues differentially could mean that composting may not always be necessary in plant waste management and urban ecological restoration may help to reduce waste output from cities