Quantification of regulating ecosystem services provided by weeds in annual cropping systems using a systematic map approach

Cian Blaix received a PhD grant from the Scuola Superiore Sant'Anna in Pisa in the International PhD Programme on AgrobiodiversityEcosystem services have received increasing attention in life sciences, but only a limited amount of quantitative data are available concerning the ability of weeds to provide these services. Following an expert focus group on this topic, a systematic search for articles displaying evidence of weeds providing regulating ecosystem services was performed, resulting in 129 articlesPostprint (updated version

Comparing impacts of new cropping systems on biodiversity in traditional rural China

This study selected six geographically-similar villages with traditional and alternative cultivation methods (two groups of three, one traditional and two alternatives) in two counties of Henan Province, China—a representative area of the Huang-huai-hai Plain representing traditional rural China. Soil heavy metal concentrations, floral and faunal biodiversity, and socio-economic data were recorded. Heavy metal concentrations of surface soils from three sites in each village were analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS, chromium, nickel, copper, cadmium, and lead) and Atomic Absorption Spectrophotometer (AAS, zinc). The floral biodiversity of four land-use types was recorded following the Braun-Blanquet coverage-abundance method using 0.5×0.5m quadrats. The faunal biodiversity of two representative farmland plots was recorded using 0.3×0.3m quadrats at four 0.1m layers. The socio-economic data were recorded through face-to-face interviews of one hundred randomly selected households at each village. Results demonstrate different cultivation methods lead to different impact on above variables. Traditional cultivation led to lower heavy metal concentrations; both alternative managements were associated with massive agrochemical input causing heavy metal pollution in farmlands. Floral distribution was significantly affected by village factors. Diverse cultivation supported high floral biodiversity through multi-scale heterogeneous landscapes containing niches and habitats. Faunal distribution was also significantly affected by village factor nested within soil depth. Different faunal groups responded differently, with Acari being taxonomically diverse and Collembola high in densities. Increase in manual labour and crop number in villages using alternative cultivation may positively affect biodiversity. The results point to the conservation potential of diverse cultivation methods in traditional rural China and other regions under social and political reforms, where traditional agriculture is changing to unified, large-scale mechanized agriculture. This study serves as a baseline for conservation in small-holding agricultural areas of China, and points to the necessity of further studies at larger and longer scales

Ecological and sociological aspects of the Phalaris minor epidemic in the rice-wheat system of Haryana, India

The fertile Indo-Gangetic plains of northern India are well suited for intensive crop production systems and provide food grains to millions of people living on the Indian subcontinent. The prevalent agro-ecological circumstances in the rice-wheat system of the Indo-Gangetic plains allowed Phalaris minor to become a ubiquitous weed infesting around 16m hectares of wheat, and causing yield losses up to 80%. The weed has hitherto been controlled by the phenyl-urea herbicide isoproturon, but the development of herbicide resistance among P. minor biotypes in the early 1990s drastically reduced control. Since then, newly introduced herbicides have relieved the weed pressure. However, the continuing risk that P. minor biotypes develop cross-resistance against other herbicides stresses the need for an integrated weed management strategy for the region. The present thesis addressed ecological and wider socio-economic aspects of the P. minor epidemic in the rice-wheat system of Haryana State in northwest India. Three types of complementary field studies have been conducted: (1) studies of the soil seedbank dynamics of P. minor, (2) research on the lifecycle of P. minor as affected by tillage regime and herbicides and (3) a farmer survey concerned with the wider agronomic and socio-economic impacts of the P. minor epidemic. A population dynamics model of P. minor in competition with wheat was developed to organise and integrate existing knowledge of biology and ecology of P .minor with new experimental observations made in the current study. The model was used to test alternative weed control strategies. A second modelling study, of the effect of aggregation among farmers on the adoption rate of technological innovations, aimed to provide novel techniques to incorporate heterogeneity in societies into quantitative models of adoption processes. Soil seedbank studies showed that P. minor seed half-life time is often limited to less than one year. Location and depth of burial were among the factors that affected seed longevity and longest seed longevity was observed when seeds were buried under anaerobic soil conditions at 30cm depth. Studies on the effect of soil cultivations on the vertical movement of seeds throughout the soil profile suggested that the practice of mouldboard ploughing before wheat sowing may assist in curbing P. minor populations by moving seeds to depths from which they cannot emerge. Straw burning was found to have a strong impact on the survival of seeds lying on the soil surface, while seeds covered with soil and slightly protected from strong heat usually survived straw burning. The results highlighted the importance of soil seedbank processes for P. minor's entire population dynamics. Lifecycle studies have revealed that application of zero tillage systems reduces P. minor pressure by diminishing the emergence rate of first and second flush seedlings. Herbicide applications suggested that isoproturon-resistant P. minor biotypes exhibit cross-resistance against the newly introduced herbicide fenoxaprop-P-ethyl. A strong linear relationship was found between P. minor vegetative weight and reproductive output. The data suggested that large seed losses occur between the stage of seeds on the mother plant and the soil seedbank at the beginning of the following growing season. The lifecycle model assigned an important role to zero tillage in curbing P. minor populations when herbicide inputs are low. The model also suggested that P. minor can be controlled effectively without the use of herbicides provided that 50% of land is used for winter crops other than wheat each season. It is concluded that crop diversification should have a central place in the development of an integrated weed control strategy to reduce reliance on herbicide for weed control. The socio-economic survey gave evidence for the existence of classes of farmers in Haryana with different socio-economic backgrounds, who had unequal access to information on farming and varied in their ability to adopt technical innovations aiming to improve P. minor control. This may lead to a widening gap in adoption levels of technology and socioeconomic strength between farmer classes in the future, which may ultimately result in expulsion of many small farmers out of farming. While the resulting consolidation of farming might be advantageous for the business at a macro-economic scale, the social consequences of disappearing rural livelihoods may be grave. This can be avoided by making innovative technologies available to small-scale farmers. As small farmers are likely to remain a significant feature of farming in Haryana in the near future, improving the accessibility of higher technologies to smaller farmers would enhance the general level of technology adoption in Haryana. This in turn, may provide opportunities to diversify the present cropping pattern, benefiting P. minor control as well as the entire sustainability of the farming system in Haryana

Risks, impacts and management of invasive plant species in Vietnam

In Southeast Asia, research on invasive plant species (IPS) is limited and biased by geography, research foci and approaches. This may hinder understanding of the extent of invasion problems and effective management to prevent and control IPS. Because biological invasions are a complicated issue involving multiple disciplines, this thesis utilized diverse approaches to evaluate risk, impacts, and management of IPS in Vietnam. Distribution models of 14 species predicted that large areas of Vietnam are susceptible to IPS, particularly in parts bordering China. Native IPS, which are often overlooked in assessment, posed similar risks as non-native IPS. From the model results, a native grass Microstegium ciliatum was selected to quantify its impacts on tree regeneration in secondary forests. A field experiment in Cuc Phuong National Park found that tree seedling abundance and richness increased within one year of grass removal; this effect strengthened in the second year. These results highlight the impacts of IPS on tree regeneration and the importance of IPS management to forest restoration projects. Given the risks and impacts of IPS, strategic management is needed to achieve conservation goals in national parks (NPs). However, interviews with both state and non-state entities revealed poor and reactive management of IPS in Vietnamese NPs from national to local levels. Institutional arrangements challenge IPS management in Vietnam. Involvement of multiple sectors with unclear mandates leads to overlaps in responsibilities and makes collaboration among sectors difficult. Lack of top-down support from the national level (legislation, guidance, resources) and limited power at the local level weakens implementation and ability of NPs to respond to IPS. The findings of this thesis provide important information for achieving effective management of IPS in Vietnam. Knowledge of vulnerable areas and species likely to invade and cause impacts can help Vietnam efficiently allocate management resources to prevent and control IPS, but adjustments to institutional arrangements and enhanced cooperation may be necessary to ensure management occurs

Evolution of the landscape of Madeira Island: long-term vegetation dynamics

The aim of this thesis was to evaluate historical change of the landscape of Madeira Island and to assess spatial and temporal vegetation dynamics. In current research diverse “retrospective techniques”, such as landscape repeat photography, dendrochronology, and research of historical records were used. These, combined with vegetation relevés, aimed to gather information about landscape change, disturbance history, and vegetation successional patterns. It was found that landscape change, throughout 125 years, was higher in the last five decades manly driven by farming abandonment, building growth and exotic vegetation coverage increase. Pristine vegetation was greatly destroyed since early settlement and by the end of the nineteenth century native vegetation was highly devastated due to recurrent antropogenic disturbances. These actions also helped to block plant succession and to modify floristical assemblages, affecting as well as species richness. In places with less hemeroby, although significant growth of vegetation of lower seral stages was detected, the vegetation of most mature stages headed towards unbalance between recovery and loss, being also very vulnerable to exotic species encroachment. Recovery by native vegetation also occurred in areas formerly occupied by exotic plants and agriculture but it was almost negligible. Vegetation recovery followed the successional model currently proposed, attesting the model itself. Yet, succession was slower than espected, due to lack of favourable conditions and to recurrent disturbances. Probable tempus of each seral stage was obtained by growth rates of woody taxa estimated through dendrochronology. The exotic trees which were the dominant trees in the past (Castanea sativa and Pinus pinaster) almost vanished. Eucalyptus globulus, the current main tree of the exotic forest is being replaced by other cover types as Acacia mearnsii. The latter, along with Arundo donax, Cytisus scoparius and Pittosporum undulatum are currently the exotic species with higher invasive behaviour. However, many other exotic species have also proved to be highly pervasive and came together with the ones referred above to prevent native vegetation regeneration, to diminish biological diversity, and to block early successional phases delaying native forest recovery.ARDITI; Rumos; QRE