Semi-natural Ecosystems Research Articles

Long-term response of plant communities to herbivore exclusion at high elevation grasslands

Understanding the effects of herbivores on plant communities is needed for anticipating how variation in grazing regimes will impact natural and semi-natural ecosystems. Prominent ecological hypotheses predict that drastic reductions of herbivory, as have occurred in many European mountains, will trigger fast diversity loss and structural changes in grasslands, because grazing tolerant species are expected to be rapidly replaced by taller and more competitive species. The aims of this study were to test generalizations of herbivory effects (mostly from lowlands) in high elevation grasslands over ecological relevant times scales, and to unravel the contribution of climatic conditions to observed changes. Species richness, canopy height, plant community structure, and transition probabilities among ecological groups were monitored throughout 19 years in herbivore exclusions and control plots in the Central Pyrenees. We used ordination analyses to track the long-term community response to herbivore exclusion, and generalized additive models to assess the non-linear effects of herbivore exclusion and climatic conditions on measured variables. Contrary to expectations, herbivore exclusion did not significantly affect species richness, and although canopy height increased, it was not drastic enough to suppress shade intolerant species. The strongest shifts in plant community structure and transition probabilities between ecological groups occurred during a sequence of warm and dry growing seasons, whereas in control plots, these changes were smaller, and largely reversed after cooler and wetter climatic conditions returned. Our results suggest that long-term effects of grazing cessation in high elevation grasslands can be weaker and slower than predicted. However, these effects can act synergistically with dry and warm events. Therefore, the maintenance of past grazing activities can be key in the face of ongoing climatic warming.

Amino acid and N mineralization dynamics in heathland soil after long-term warming and repetitive drought

Abstract. Monomeric organic nitrogen (N) compounds such as free amino acids (FAAs) are an important resource for both plants and soil microorganisms and a source of ammonium (NH4+) via microbial FAA mineralization. We compared gross FAA dynamics with gross N mineralization in a Dutch heathland soil using a 15N tracing technique. A special focus was made on the effects of climate change factors warming and drought, followed by rewetting. Our aims were to (1) compare FAA mineralization (NH4+ production from FAAs) with gross N mineralization, (2) assess gross FAA production rate (depolymerization) and turnover time relative to gross N mineralization rate, and (3) assess the effects of a 14 years of warming and drought treatment on these rates. The turnover of FAA in the soil was ca. 3 h, which is almost 2 orders of magnitude faster than that of NH4+ (i.e. ca. 4 days). This suggests that FAA is an extensively used resource by soil microorganisms. In control soil (i.e. no climatic treatment), the gross N mineralization rate (10 ± 2.9 μg N g−1 day−1) was 8 times smaller than the total gross FAA production rate of five AAs (alanine, valine, leucine, isoleucine, proline: 127.4 to 25.0 μg N g−1 day−1). Gross FAA mineralization (3.4 ± 0.2 μg N g−1 day−1) contributed 34% to the gross N mineralization rate and is therefore an important component of N mineralization. In the drought treatment, a 6–29% reduction in annual precipitation caused a decrease of gross FAA production by 65% and of gross FAA mineralization by 41% compared to control. On the other hand, gross N mineralization was unaffected by drought, indicating an increased mineralization of other soil organic nitrogen (SON) components. A 0.5–1.5 °C warming did not significantly affect N transformations, even though gross FAA production declined. Overall our results suggest that in heathland soil exposed to droughts a different type of SON pool is mineralized. Furthermore, compared to agricultural soils, FAA mineralization was relatively less important in the investigated heathland. This indicates more complex mineralization dynamics in semi-natural ecosystems.

Sustainable management of river oases along the Tarim River (SuMaRiO) in Northwest China under conditions of climate change

Abstract. The Tarim River basin, located in Xinjiang, NW China, is the largest endorheic river basin in China and one of the largest in all of Central Asia. Due to the extremely arid climate, with an annual precipitation of less than 100 mm, the water supply along the Aksu and Tarim rivers solely depends on river water. This is linked to anthropogenic activities (e.g., agriculture) and natural and semi-natural ecosystems as both compete for water. The ongoing increase in water consumption by agriculture and other human activities in this region has been enhancing the competition for water between human needs and nature. Against this background, 11 German and 6 Chinese universities and research institutes have formed the consortium SuMaRiO (Sustainable Management of River Oases along the Tarim River; http://www.sumario.de), which aims to create a holistic picture of the availability of water resources in the Tarim River basin and the impacts on anthropogenic activities and natural ecosystems caused by the water distribution within the Tarim River basin. On the basis of the results from field studies and modeling approaches as well as from suggestions by the relevant regional stakeholders, a decision support tool (DST) will be implemented that will then assist stakeholders in balancing the competition for water, acknowledging the major external effects of water allocation to agriculture and to natural ecosystems. This consortium was formed in 2011 and is funded by the German Federal Ministry of Education and Research. As the data collection phase was finished this year, the paper presented here brings together the results from the fields from the disciplines of climate modeling, cryology, hydrology, agricultural sciences, ecology, geoinformatics, and social sciences in order to present a comprehensive picture of the effects of different water availability schemes on anthropogenic activities and natural ecosystems along the Tarim River. The second objective is to present the project structure of the whole consortium, the current status of work (i.e., major new results and findings), explain the foundation of the decision support tool as a key product of this project, and conclude with application recommendations for the region. The discharge of the Aksu River, which is the major tributary of the Tarim, has been increasing over the past 6 decades. From 1989 to 2011, agricultural area more than doubled: cotton became the major crop and there was a shift from small-scale to large-scale intensive farming. The ongoing increase in irrigated agricultural land leads to the increased threat of salinization and soil degradation caused by increased evapotranspiration. Aside from agricultural land, the major natural and semi-natural ecosystems are riparian (Tugai) forests, shrub vegetation, reed beds, and other grassland, as well as urban and peri-urban vegetation. Within the SuMaRiO cluster, focus has been set on the Tugai forests, with Populus euphratica as the dominant tree species, because these forests belong to the most productive and species-rich natural ecosystems of the Tarim River basin. At sites close to the groundwater, the annual stem diameter increments of Populus euphratica correlated with the river runoffs of the previous year. However, the natural river dynamics cease along the downstream course and thus hamper the recruitment of Populus euphratica. A study on the willingness to pay for the conservation of the natural ecosystems was conducted to estimate the concern of the people in the region and in China's capital. These household surveys revealed that there is a considerable willingness to pay for conservation of the natural ecosystems, with mitigation of dust and sandstorms considered the most important ecosystem service. Stakeholder dialogues contributed to creating a scientific basis for a sustainable management in the future.

Global Trends in Exposure to Light Pollution in Natural Terrestrial Ecosystems

The rapid growth in electric light usage across the globe has led to increasing presence of artificial light in natural and semi-natural ecosystems at night. This occurs both due to direct illumination and skyglow - scattered light in the atmosphere. There is increasing concern about the effects of artificial light on biological processes, biodiversity and the functioning of ecosystems. We combine intercalibrated Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) images of stable night-time lights for the period 1992 to 2012 with a remotely sensed landcover product (GLC2000) to assess recent changes in exposure to artificial light at night in 43 global ecosystem types. We find that Mediterranean-climate ecosystems have experienced the greatest increases in exposure, followed by temperate ecosystems. Boreal, Arctic and montane systems experienced the lowest increases. In tropical and subtropical regions, the greatest increases are in mangroves and subtropical needleleaf and mixed forests, and in arid regions increases are mainly in forest and agricultural areas. The global ecosystems experiencing the greatest increase in exposure to artificial light are already localized and fragmented, and often of particular conservation importance due to high levels of diversity, endemism and rarity. Night time remote sensing can play a key role in identifying the extent to which natural ecosystems are exposed to light pollution.

Nitrogen deposition and prey nitrogen uptake control the nutrition of the carnivorous plant Drosera rotundifolia

Nitrogen (N) deposition has important negative impacts on natural and semi-natural ecosystems, impacting on biotic interactions across trophic levels. Low-nutrient systems are particularly sensitive to changes in N inputs and are therefore more vulnerable to N deposition. Carnivorous plants are often part of these ecosystems partly because of the additional nutrients obtained from prey. We studied the impact of N deposition on the nutrition of the carnivorous plant Drosera rotundifolia growing on 16 ombrotrophic bogs across Europe. We measured tissue N, phosphorus (P) and potassium (K) concentrations and prey and root N uptake using a natural abundance stable isotope approach. Our aim was to test the impact of N deposition on D. rotundifolia prey and root N uptake, and nutrient stoichiometry. D. rotundifolia root N uptake was strongly affected by N deposition, possibly resulting in reduced N limitation. The contribution of prey N to the N contained in D. rotundifolia ranged from 20 to 60%. N deposition reduced the maximum amount of N derived from prey, but this varied below this maximum. D. rotundifolia tissue N concentrations were a product of both root N availability and prey N uptake. Increased prey N uptake was correlated with increased tissue P concentrations indicating uptake of P from prey. N deposition therefore reduced the strength of a carnivorous plant–prey interaction, resulting in a reduction in nutrient transfer between trophic levels. We suggest that N deposition has a negative impact on D. rotundifolia and that responses to N deposition might be strongly site specific.

Future changes in the supply of goods and services from natural ecosystems: prospects for the European north

Humans depend on services provided by ecosystems, and how services are affected by climate change is increasingly studied. Few studies, however, address changes likely to affect services from seminatural ecosystems. We analyzed ecosystem goods and services in natural and seminatural systems, specifically how they are expected to change as a result of projected climate change during the 21st century. We selected terrestrial and freshwater systems in northernmost Europe, where climate is anticipated to change more than the global average, and identified likely changes in ecosystem services and their societal consequences. We did this by assembling experts from ecology, social science, and cultural geography in workshops, and we also performed a literature review. Results show that most ecosystem services are affected by multiple factors, often acting in opposite directions. Out of 14 services considered, 8 are expected to increase or remain relatively unchanged in supply, and 6 are expected to decrease. Although we do not predict collapse or disappearance of any of the investigated services, the effects of climate change in conjunction with potential economical and societal changes may exceed the adaptive capacity of societies. This may result in societal reorganization and changes in ways that ecosystems are used. Significant uncertainties and knowledge gaps in the forecast make specific conclusions about societal responses to safeguard human well-being questionable. Adapting to changes in ecosystem services will therefore require consideration of uncertainties and complexities in both social and ecological responses. The scenarios presented here provide a framework for future studies exploring such issues.

Eco-exergy-based ecological flow accounting of cropland ecosystem and utilisation efficiencies in China

A quantitative analysis of the development of ecological flow patterns of various types is performed. On the basis of existing exergy accounting, ecological flow networks in a typical semi-natural cropland ecosystem were analysed, and five ecological indicators used to compare spatial and temporal differences from 2000 to 2011 in 31 provinces of mainland China. The results show that according to system transformity, the utilisation effectiveness of cropland ecosystems has increased from 20.22% to 23.23%, with major grain producing provinces in central China growing significantly. Annual renewable resource dependency has gradually decreased from 93.90% to 89.52%. The analysis of natural resources utilisation and material flow suggests that the use of natural resources needs to be more conservative, particularly in coastal provinces, and that economic development needs to be guaranteed. The results can provide guidance for future policy-oriented agriculture sustainable development.

Neophytes In Protected Areas. Case Study: The Danube Delta Biosphere Reserve

Abstract The Danube Delta is a relatively young territory, formed about 14,000 years ago. It has quadruple status: Biosphere Reserve, Ramsar site, UNESCO World Heritage site, Natura 2000 site. Water and human activities are the most important factors influencing the flora of this area, including the penetration and spread of alien plants. The main goal of our research in this area was to inventory the alien plants and to identify those species which are invasive and potentially invasive in the natural and semi-natural ecosystems in order to propose measures for their prevention and mitigation. An inventory of these plants, conducted between 2009 and 2012 and based on bibliography and field research, comprises over 160 taxa. About half of them originated from America and less than a quarter of them from Asia. A relatively high number of species have unknown status in the Danube Delta; they were reported only from one or two localities and we did not record them during our extensive field work. In this category we also included some taxa of Xanthium without a very clear taxonomy. The taxa recorded as casual are usually ornamental plants escaped from cultivation; however among them there are some species which are known as invasive in other areas of Romania, as well as in Europe. There are 26 naturalised species, two of which established here over one hundred years ago. 37 invasive species were identified, many of them recorded in natural or seminatural places. In order to prevent and mitigate the spread of plants recognised as invasive, we propose the implementation of some measures such as providing relevant information to local communities and raising awareness about the damages caused by the alien species, and promoting further research on alien plant species in this protected area.

Chromolaena odorata invasion in Nigeria: A case for coordinated biological control

Chromolaena odorata (L.) King and Robinson (Asteraceae: Eupatorieae) is an invasive perennial weedy scrambling shrub of neotropical origin, widely acknowledged as a major economic and ecological burden to many tropical and subtropical regions of the world including Nigeria. Here, we examine the invasion and management of C. odorata in Nigeria over the last seven decades using historical records and field surveys and ask: (i) Does the usefulness of C. odorata influence its invasion success? (ii) Is a coordinated control approach against C. odorata needed in the face of its usefulness or do we need to develop strategies for its adaptive management? We searched major institutional libraries in Nigeria and carried out extensive research of historical records using different data base platforms, including Google Scholar, Science Direct, ISI web of Science, SciFinders and Scopus. Apart from the biological invasive characteristics of C. odorata and the increased anthropogenic disturbances occurring over the time period, the records indicate that the ethno-pharmacological, funcigicidal, nematicidal importance of the plant and its use as a fallow species and as a soil fertility improvement plant in the slash and burn rotation system of agriculture is partly responsible for the invasion success of the weed. The current distribution and infestation levels of this invasive weed in Nigeria are mapped. The current methods of control and the failed attempt made by the Nigerian government to eradicate the weed between the late 1960s and 1970s are discussed. We argue that even in the face of the usefulness of C. odorata, it is reasonable to implement a nationwide coordinated control programme against it with biological control as a core component, because weed biological control does not eliminate the target species, instead it aims to establish an equilibrium which maintains the weed’s population below the level where it causes significant harm to natural and semi-natural ecosystems.

Disentangling the environmental-heterogeneity--species-diversity relationship along a gradient of human footprint.

Decades of study have attempted to define a generalized environmental-heterogeneity-biodiversity (EH-BD) relationship, with the traditional MacArthurian niche-based hypothesis remaining as the dominant reference point; i.e., increasing heterogeneity promotes biodiversity by increasing resource opportunities. However, studies have frequently reported negative or nonsignificant relationships. In a vast majority of them, environmental heterogeneity was defined along a gradient of increasing randomness, toward complete disorder. A new conceptual framework could help to reconcile the array of observed relationships. Using an extensive literature review, we test a conceptual framework proposing that the direction of environmental-heterogeneity-biodiversity relationships is contingent on the level of human footprint to which an ecosystem is subjected (the anthropocline). The results reveal that highly modified and seminatural ecosystems are characterized by a dominance of positive and negative EH-BD relationships, respectively, whereas natural ecosystems show mixed responses. Out of this novel framework arises the revised perspective that natural ecosystems are typified, not by maximal or minimal, but by intermediate levels of environmental heterogeneity.

Energy potential for combustion and anaerobic digestion of biomass from low‐input high‐diversity systems in conservation areas

AbstractIn this study, we assessed the potential for bioenergy production of Low‐Input High‐Diversity (LIHD) systems in temperate West‐European conservation areas. A wide range of seminatural ecosystems (wet and dry grasslands, marshes, tall‐herb vegetation and heathlands) was sampled. Because LIHD biomass is often scattered and discontinuously available, we only considered the potential for anaerobic digestion and combustion. Both technologies are suitable for decentralized biomass utilization. The gross energy yield showed a promising range between 46–277 GJ per hectare per mowing cycle (MC). The energy efficiency of the anaerobic digestion process was rather low (10–30%) with a methane energy yield of 5.5–35.5 GJ ha−1 MC−1, experimentally determined by batch digestion tests. The water content, functional group composition and biochemical composition (hemicellulose, cellulose, lignin and Kjeldahl nitrogen) of the biomass were analyzed to assess the suitability of different valorization pathways. On the basis of the results, we were able to propose recommendations regarding the appropriate conversion techniques. Biomass from plant communities with ‘late’ harvest dates (August–October) or a high fraction of woody species like heathland and dune slacks, is best valorized through combustion, while herbaceous biomass of ‘early’ harvested grasslands (June–July) and tall‐herb vegetation can better be digested. The main advantages of the production of bioenergy from LIHD biomass originating from conservation management are the minimization of the competition with food production and its potential to reconcile renewable energy policies and biodiversity goals.

Estimating Fractional Shrub Cover Using Simulated EnMAP Data: A Comparison of Three Machine Learning Regression Techniques

Anthropogenic interventions in natural and semi-natural ecosystems often lead to substantial changes in their functioning and may ultimately threaten ecosystem service provision. It is, therefore, necessary to monitor these changes in order to understand their impacts and to support management decisions that help ensuring sustainability. Remote sensing has proven to be a valuable tool for these purposes, and especially hyperspectral sensors are expected to provide valuable data for quantitative characterization of land change processes. In this study, simulated EnMAP data were used for mapping shrub cover fractions along a gradient of shrub encroachment, in a study region in southern Portugal. We compared three machine learning regression techniques: Support Vector Regression (SVR); Random Forest Regression (RF); and Partial Least Squares Regression (PLSR). Additionally, we compared the influence of training sample size on the prediction performance. All techniques showed reasonably good results when trained with large samples, while SVR always outperformed the other algorithms. The best model was applied to produce a fractional shrub cover map for the whole study area. The predicted patterns revealed a gradient of shrub cover between regions affected by special agricultural management schemes for nature protection and areas without land use incentives. Our results highlight the value of EnMAP data in combination with machine learning regression techniques for monitoring gradual land change processes.

Bioenergy, Food Production and Biodiversity – An Unlikely Alliance?

School of Biological Sciences, Plymouth University, DrakeCircus PL4 8AA Plymouth, UKReceived 27 November 2013; accepted 20 January 2014IntroductionThe global demand for bioenergy is set to increase to apoint where it may supply up to one-third of globalprimary energy by 2050 (IEA, 2012). Current cultivationof biofuel and bioenergy crops has attracted consider-able criticism due to their encroachment into areas tra-ditionally occupied by food crops and natural andseminatural ecosystems. Among the most notorious ofthese bioenergy crops are sugarcane, jotropha, ethanolmaize, and palm oil, crops closely associated with biodi-versity and habitat loss, water deficit, and perhaps mostironically, given their potential for greenhouse gas emis-sions reduction, negative impacts on carbon storage andsequestration (Fargione et al., 2008; Martinelli & Filoso,2008; Koh et al., 2009; Romijn, 2011). In the medium-term bioenergy demand is likely to be met by so-calledsecond-generation (2G) lignocellulose crops, principallyperennial grasses and woody trees (Somerville et al.,2010). Many of the problems associated with establishedfirst-generation biofuel crops, which are often also foodcrops, could be avoided by cultivating 2G bioenergycrops on existing farmland. However, this option isoften undesirable due to increasing food demand andthe potential displacement of food crops (Dauber et al.,2010; Godfray et al., 2010; Gelfand et al., 2013). This con-flict between land use objectives, the so-called ‘food,energy, environment trilemma’ (Tilman et al., 2009),raises concerns that increased demand for bioenergycrops will displace food production and/or cause fur-ther destruction of natural and seminatural (so-calledmarginal) ecosystems. The problems of potential biodi-versity loss and land competition with food productionremain central to the debate surrounding the possiblecontribution that bioenergy crops could make towardsmeeting renewable energy and greenhouse gas emis-sions targets (Nonhebel, 2012). Policy makers are leftstruggling with the problems that have doggedbioenergy cultivation for decades; where should 2G bio-energy crops be planted and what proportion of landshould they occupy? Such questions raise doubts as tothe viability of bioenergy as a major future energysource; a major recent report into bioenergy crop viabil-ity in the United States concluded that economic andenvironmental uncertainty will strongly limit futuredeployment of 2G crops (Committee on Economic E Carvell et al., 2007, 2011;Whittingham, 2011), but this approach is not widelyapplied to bioenergy crops at present. Our second pro-posal is that new bioenergy plantations are located in amore strategic way that considers landscape context andis sensitive to how they affect biodiversity and ecosystemservices (Table 2). This involves planning the spatialarrangement of bioenergy plantations so that they inter-act positively with other landscape units. It also requiresan understanding of how the impact of bioenergy cropson biodiversity and food security varies depending upon

Does prescribed burning result in biotic homogenization of coastal heathlands?

Biotic homogenization due to replacement of native biodiversity by widespread generalist species has been demonstrated in a number of ecosystems and taxonomic groups worldwide, causing growing conservation concern. Human disturbance is a key driver of biotic homogenization, suggesting potential conservation challenges in seminatural ecosystems, where anthropogenic disturbances such as grazing and burning are necessary for maintaining ecological dynamics and functioning. We test whether prescribed burning results in biotic homogenization in the coastal heathlands of north-western Europe, a seminatural landscape where extensive grazing and burning has constituted the traditional land-use practice over the past 6000years. We compare the beta-diversity before and after fire at three ecological scales: within local vegetation patches, between wet and dry heathland patches within landscapes, and along a 470km bioclimatic gradient. Within local patches, we found no evidence of homogenization after fire; species richness increased, and the species that entered the burnt Calluna stands were not widespread specialists but native grasses and herbs characteristic of the heathland system. At the landscapes scale, we saw a weak homogenization as wet and dry heathland patches become more compositionally similar after fire. This was because of a decrease in habitat-specific species unique to either wet or dry habitats and postfire colonization by a set of heathland specialists that established in both habitat types. Along the bioclimatic gradient, species that increased after fire generally had more specific environmental requirements and narrower geographical distributions than the prefire flora, resulting in a biotic 'heterogenisation' after fire. Our study demonstrates that human disturbance does not necessarily cause biotic homogenization, but that continuation of traditional land-use practices can instead be crucial for the maintenance of the diversity and ecological function of a seminatural ecosystem. The species that established after prescribed burning were heathland specialists with relatively narrow geographical ranges.

Glucose decomposition and its incorporation into soil microbial biomass depending on land use in Mt. Kilimanjaro ecosystems

Land use change can affect terrestrial C stocks, resulting in increased CO2 flux from soil to the atmosphere. In Africa, conversion of natural ecosystems to agricultural lands is the most common land use change. This study investigated the effects of six land use types occurring in Mt. Kilimanjaro ecosystems i.e. (1) lower montane forest (2) grassland and (3) savannah (natural ecosystems) (4) Chagga homegardens (semi-natural ecosystem) and (5) maize fields and (6) coffee plantation (agroecosystems) on microbial biomass carbon (MBC) and dynamics of 14C labelled glucose added into soil. Decomposition of 14C labelled glucose and its incorporation into microbial biomass in surface soils (0–10 and 10–20 cm) were determined. MBC decreased significantly with increased intensity of land use. Mineralization of the 14C labelled glucose occurred in two phases with contrasting rates: 0–10 days (6–18% of 14C d−1) and 15–65 days (<0.1% of 14C d−1). Land use intensification in agroecosystems led to an average increase of glucose decomposition of 14%. The decay rates of the labile C pool in intensively used agricultural lands were up to three times higher compared to natural ecosystems. The incorporation of 14C glucose into microorganisms ranged between 1 and 7% of 14C input in all soils, and was highest in savannah. Agricultural intensification decreased C content in soil through increased mineralization of organic substances and negatively impacted the upper soil layer more compared to the lower one. Based on these results we conclude that semi-natural ecosystems (e.g. Chagga homegardens) are more sustainable in Mt. Kilimanjaro ecosystems compared to intensive agroecosystems.

Management-driven evolution in a domesticated ecosystem

Millennia of human land-use have resulted in the widespread occurrence of what have been coined ‘domesticated ecosystems’. The anthropogenic imprints on diversity, composition, structure and functioning of such systems are well documented. However, evolutionary consequences of human activities in these ecosystems are enigmatic. Calluna vulgaris (L.) is a keystone species of coastal heathlands in northwest Europe, an ancient semi-natural landscape of considerable conservation interest. Like many species from naturally fire-prone ecosystems, Calluna shows smoke-adapted germination, but it is unclear whether this trait arose prior to the development of these semi-natural landscapes or is an evolutionary response to the anthropogenic fire regime. We show that smoke-induced germination in Calluna is found in populations from traditionally burnt coastal heathlands but is lacking in naturally occurring populations from other habitats with infrequent natural fires. Our study thus demonstrates evolutionary imprints of human land-use in semi-natural ecosystems. Evolutionary consequences of historic anthropogenic impacts on wildlife have been understudied, but understanding these consequences is necessary for informed conservation and ecosystem management.

Cessation effects of grazing and burning on species composition in humid temperate semi-natural grasslands through environmental modifications

To elucidate the cessation impacts of agricultural management on a semi-natural grassland ecosystem, effects of grazing and burning on species composition of vascular plants were investigated in Mt. Aso, Japan. Species richness was significantly increased by both grazing and burning at the plot scale (1 m2), and a negative interaction between grazing and burning was recognized by two-way analysis of variance. No significant effect existed at the transect (10 m2) or the site (20 m2) scales. Most of the environmental factors measured in this study (e.g. soil physical properties) were significantly, although differently, modified by grazing and/or burning. According to logistic regression analyses, 32 of 77 species recorded at the study sites were significantly correlated with the environmental variables, yet each species appeared to respond to the environmental factors in different ways. Canonical correspondence analysis showed that both grazing and burning are important factors in determining species composition; that cessation of grazing changes shortgrass communities to tallgrass ones; and that cessation of burning changes communities composed of colorful-flowering species to shrubby communities. This study concludes that within several years of the cessation of grazing and burning, species richness could be lowered in semi-natural grasslands at such small scales as 1-m2 plots. Grazing and burning would modify some environmental factors, especially hydraulic conditions, in semi-natural grasslands, and would create various habitat types for plants, thus allowing species diversity to be maintained over time.

Phosphorus availability explains patterns in a productivity indicator in temperate semi-natural vegetation.

Plant production is a key process in semi-natural ecosystems, affecting resource provision, carbon storage, and habitat suitability for species of conservation concern. There is debate over whether nitrogen (N) or phosphorus (P) limits productivity more widely, and whether the pattern of limitation has been affected by widespread atmospheric N pollution. In a national-scale survey, floristic composition was used to derive mean Ellenberg N score (EN) for use as an independent metric of productivity. Much of the variation in EN within extensively-managed habitats could be explained by bulk-soil properties such as total C and moisture contents, reflecting the axis from wet, organic, infertile soils to drier, mineral, fertile soils. However, this main axis of variation was also explained well by bicarbonate-extractable P stock, and P stock was included in the best 88 of 255 possible models for all habitats, or the best 55 of 255 models for extensively-managed habitats. The stock of mineralisable N was much less well able to explain variation in the productivity metric, particularly in extensively-managed habitats. This suggests that P availability is a more widespread constraint to the productivity of semi-natural ecosystems in the UK than is N availability.

The negative impact of intentionally introduced Quercus rubra L. on a forest community

&lt;p&gt;Some alien woody species used in commercial forestry become invasive and, as invaders, cause major problems in natural and semi-natural ecosystems. However, the deliberate introduction of aliens can bring unintended negative changes also within areas of their cultivation. This paper presents the effects of the intentional introduction of the North-American &lt;em&gt;Quercus rubra&lt;/em&gt; in European mixed Scots pine-Pedunculate oak forests (POFs): &lt;em&gt;Querco roboris-Pinetum&lt;/em&gt; (W. Mat. 1981) J. Mat. 1988. Phytosociological data from field research combined with GIS data analysis of the current distribution of Northern Red oak in the studied habitat were used to determine the composition and structure of forest communities in plots with and without &lt;em&gt;Q. rubra&lt;/em&gt; participation. &lt;/p&gt;&lt;p&gt;The results show that &lt;em&gt;Q. rubra&lt;/em&gt; significantly reduces native species richness and abundance, both in old-growth and in secondary (post-agricultural) forests. Not one resident vascular plant benefits from the introduction of Northern Red oak and only a few are able to tolerate its co-occurrence. The natural restocking of all native woody species is also strongly limited by this alien tree. &lt;/p&gt;&lt;p&gt;The introduction of Northern Red oak significantly limits the environmental functions of the POF ecosystem and weakens its economic and social aspects. However, its further cultivation is justified from an economic point of view, as the essential function of the studied forests is commercial timber production, and the introduction of this fast growing alien tree supports the provisioning ecosystem services. A clear description of the level of trade-off between the accepted negative and positive effects of the introduction of &lt;em&gt;Q. rubra&lt;/em&gt; on forest ecosystem services requires further interdisciplinary studies.&lt;/p&gt;

Governance of Ecosystem Services: insights from Life+ Making Good Natura project

The Natura 2000 network is the cornerstone of EU Biodiversity Strategy aimed at halting the loss of biodiversity and services natural and semi-natural ecosystems provide to human populations. The Member States are mainly responsible to implement conservation strategies through management plans and conservation measures, but in many cases the level of development and execution of these instruments is very low due to scarce financial resources, and management effectiveness is rarely achieved. This paper presents first insights from Life+ Making Good Natura (MGN) project and highlights costs and benefits associated to 2 out of 21 Natura 2000 study sites in Italy in order to define the basis for a new governance approach relied on the qualitative and quantitative valuation of ecosystem services (ES) and suitable for reaching management effectiveness. To date, the habitat cover of the agro-forest sites and socio-economic data for the core area and a buffer zone of 20 km, gathered through questionnaires to management authority, have been analyzed. After mapping and assessing the most important ES for each site based on spatial data and on the information from the questionnaires, meetings with local public and private stakeholders were organized in order to discuss the identified ES and their social and economic importance for the area. Preliminary results suggest that quantification of costs related to the Natura 2000 network is a crucial point within a systematic approach to environmental accountability that allows to measure and assess management bodies’ management strategy effectiveness and efficiency and to redefine Natura 2000 sites conservation priorities. Furthermore, in a general context of stagnant and uncertain funding for biodiversity conservation, also the need of defining a wide range of governance and management tools, referring to the policy mix instruments, seems urgent.