Gradient Of Management Intensity Research Articles

Local and Landscape Effects on Carrion-Associated Rove Beetle (Coleoptera: Staphylinidae) Communities in German Forests.

Simple SummaryIncreasing forest management practices by humans are threatening inherent insect biodiversity and thus important ecosystem services provided by them. One insect group which reacts sensitively to habitat changes are the rove beetles contributing to the maintenance of an undisturbed insect succession during decomposition by mainly hunting fly maggots. However, little is known about carrion-associated rove beetles due to poor taxonomic knowledge. In our study, we unveiled the human-induced and environmental drivers that modify rove beetle communities on vertebrate cadavers. At German forest sites selected by a gradient of management intensity, we contributed to the understanding of the rove beetle-mediated decomposition process. One main result is that an increasing human impact in forests changes rove beetle communities by promoting generalist and more open-habitat species coping with low structural heterogeneity, whereas species like Philonthus decorus get lost. Our results are not solely important for carrion ecological, but also for forensic entomological assessments on crime scenes, e.g., postmortem body relocation, because little information is available until now about rove beetles as one of the most important insect groups on bodies.Intensification of anthropogenic land use is a major threat to biodiversity and thus to essential ecosystem services provided by insects. Rove beetles (Coleoptera: Staphylinidae), which react sensitively to habitat changes, are species-rich colonizers of vertebrate cadavers and contribute to the important ecosystem service of carrion decomposition. The unveiling of anthropogenic and environmental drivers that modify carrion-associated rove beetle communities should improve our understanding of the plasticity of cadaver decay. We report the presence of 80 rove beetle species on 65 decomposing piglet cadavers at forest sites characterized by a gradient of management intensity across three geographic regions in Germany. Local and landscape drivers were revealed that shape beetle abundance, diversity, and community composition. Forest management and regions affect rove beetle abundance, whereas diversity is influenced by local habitat parameters (soil pH, litter cover) and regions. The community composition of rove beetles changes with management intensification by promoting generalist species. Regarding single species, Philonthus decorus and Anotylus mutator are linked to unmanaged forests and Ontholestes tessellatus to highly used forest stands. The spatial information provided about carrion-associated rove beetle communities in German forests is not only of carrion-ecological but also of forensic entomological interest.

Niche Differentiation of Bacterial Versus Archaeal Soil Nitrifiers Induced by Ammonium Inhibition Along a Management Gradient.

Soil nitrification, mediated mainly by ammonia oxidizing archaea (AOA) and bacteria (AOB), converts ammonium (NH4+) to nitrite (NO2−) and thence nitrate (NO3−). To better understand ecological differences between AOA and AOB, we investigated the nitrification kinetics of AOA and AOB under eight replicated cropped and unmanaged ecosystems (including two fertilized natural systems) along a long-term management intensity gradient in the upper U.S. Midwest. For five of eight ecosystems, AOB but not AOA exhibited Haldane kinetics (inhibited by high NH4+ additions), especially in perennial and successional systems. In contrast, AOA predominantly exhibited Michaelis-Menten kinetics, suggesting greater resistance to high nitrogen inputs than AOB. These responses suggest the potential for NH4+-induced niche differentiation between AOA and AOB. Additionally, long-term fertilization significantly enhanced maximum nitrification rates (Vmax) in the early successional systems for both AOA and AOB, but not in the deciduous forest systems. This was likely due to pH suppression of nitrification in the acidic forest soils, corroborated by a positive correlation of Vmax with soil pH but not with amoA gene abundance. Results also demonstrated that soil nitrification potentials were relatively stable, as there were no seasonal differences. Overall, results suggest that (1) NH4+ inhibition of AOB but not AOA could be another factor contributing to niche differentiation between AOA and AOB in soil, and (2) nitrification by both AOA and AOB can be significantly promoted by long-term nitrogen inputs.

Bioaccumulation and potential ecotoxicological effects of trace metals along a management intensity gradient in volcanic pasturelands

The particularities of volcanic soils raise the need to better understand the link between soil agricultural management intensity and trace metal bioaccumulation. The Azores are a region characterized by volcanic soils, which were changed in different degrees according to the intensity of the agricultural practices. The main objective of this study was to assess the potential ecotoxicological effects of the trace metals present in volcanic pastureland soils along a gradient of management intensity (i.e., semi-natural, permanent and reseeded), using earthworms (Eisenia fetida) as biological indicators. For this purpose earthworms were exposed during 7, 14, 28 and 56 days to soils from the three types of pastures. At each exposure time, we quantified trace element bioaccumulation (As, Cd, Co, Cr, Cu, Hg, Li, Mn, Mo, Ni, Pb, Rb, U, V and Zn) and the activities of superoxide dismutase and acetylcholinesterase in earthworm tissues. Overall, the results showed that the type of pastureland management significantly increased the soil contents in trace metals: V, Co, Ni and Zn in semi-natural pasturelands; As, Cd and Hg in reseeded pasturelands; and, Rb and U in both permanent and reseeded pasturelands. The soil physicochemical properties observed in the reseeded pastureland systems (higher electric conductivity values associated with a moderately acid pH value) modulated the metal bioavailability, from soil to biota, leading to a greater Hg bioaccumulation in earthworm tissues. The long-term exposure (56 days) of earthworms to reseeded pastureland soil was associated with adverse biological effects (intensification of AChE activity and decrease of SOD activity), encompassing key processes such as neurotransmission and antioxidant defence mechanisms in resident soil biota (earthworms). This study point towards the increased importance of semi-natural and permanent pastureland management, over the intensive management (reseeded pasturelands), in favour of more sustainable ecosystems.

Quality of substrate and forest structure determine macrofungal richness along a gradient of management intensity in beech forests

The richness of saproxylic species is commonly found to be compromised in managed forests. However, it is often less clear if this reflects local scarcity of high quality deadwood objects or changes to the overall forest structure. Further, anthropogenic and natural drivers working at the landscape scale may have a strong impact. Hence, it is difficult to give detailed advice on how to conserve biodiversity in a cost-effective manner. Here we explored macrofungal richness on deadwood across a gradient of forest management intensity in Danish Fagus sylvatica forests. We aimed to disentangle the importance of habitat quality per se from the effects of variables recorded at the forest stand and landscape scales. Data was collected from 40 beech stands, each representing one of four broad management types: conventionally managed, near-to-nature managed, recently unmanaged and long unmanaged. Stands were aggregated within six larger forest clusters, to account for variation at the landscape scale. Fungal species were recorded as fruitbodies on deadwood at five decay stages. We found that the four management types showed strong differences in fungal richness, deadwood volume and forest structure, with long unmanaged stands having notably higher structural complexity and species richness. Fungal species richness and presence of red-listed fungi appeared to be mainly driven by deadwood volume, tree species and decay stage, but some stand-level variables such as canopy gaps, basal area and stand age were also of importance. Lying coarse deadwood had the highest species richness while standing coarse woody debris and fine deadwood had lower species density. Saproxylic fungal richness on individual deadwood objects was largely affected by resource quality and size, which is often limited in managed forests. Our results indicate that the best measure to increase fungal species richness, especially in managed stands, is to increase the amount of large diameter deadwood.

Using proxies of microbial community‐weighted means traits to explain the cascading effect of management intensity, soil and plant traits on ecosystem resilience in mountain grasslands

AbstractTrait‐based approaches provide a framework to understand the role of functional biodiversity on ecosystem functioning under global change. While plant traits have been reported as potential drivers of soil microbial community composition and resilience, studies directly assessing microbial traits are scarce, limiting our mechanistic understanding of ecosystem functioning.We used microbial biomass and enzyme stoichiometry, and mass‐specific enzymes activity as proxies of microbial community‐weighted mean (CWM) traits, to infer trade‐offs in microbial strategies of resource use with cascading effects on ecosystem resilience. We simulated a drought event on intact plant–soil mesocosms extracted from mountain grasslands along a management intensity gradient. Ecosystem processes and properties related to nitrogen cycling were quantified before, during and after drought to characterize ecosystem resilience.Soil microbial CWM traits and ecosystem resilience to drought were strongly influenced by grassland type. Structural equation modelling revealed a cascading effect from management to ecosystem resilience through modifications in soil nutrients, and plant and microbial CWM traits. Overall, our results depict a shift from high investment in extracellular enzymes in nutrient‐poor soils (oligotrophic strategy), to a copiotrophic strategy with low microbial biomass N:P and low investment in extracellular enzymes associated with exploitative plant traits in nutrient‐rich soils.Microbial CWM traits responses to management intensity were highly related to ecosystem resilience. Microbial communities with a copiotrophic strategy had lower resistance but higher recovery to drought, while microbial communities with an oligotrophic strategy showed the opposite responses. The unexpected trade‐off between plant and microbial resistance suggested that the lower resistance of copiotrophic microbial communities enabled plant resistance to drought.Synthesis.Grassland management has cascading effects on ecosystem resilience through its combined effects on soil nutrients and plant traits propagating to microbial traits and resilience. We suggest that intensification of permanent grassland management and associated increases in soil nutrient availability decreased plant–microbe competition for N under drought through the selection of drought‐sensitive microbial communities with a copiotrophic strategy that promoted plant resistance. Including proxies of microbial CWM traits into the functional trait framework will strengthen our understanding of soil ecosystem functioning under global change.

Stormwater ponds: An overlooked but plentiful urban designer ecosystem provides invasive plant habitat in a subtropical region (Florida, USA)

Designed ecosystems are built as part of ongoing urban expansion, providing a suite of valued ecosystem services. However, these new ecosystems could also promote disservices by facilitating the colonization and spread of invasive species. We conduct the first assessment of the quantity and invasion of an overlooked designed ecosystem: stormwater ponds. These ponds are commonly recommended for managing urban hydrology, but little is known about their ecology or extent of proliferation. Using a broad-scale survey of pond coverage in Florida, USA, we found that over 76,000 stormwater ponds have been built just in this state, forming 2.7% of total urban land cover. This extensive pondscape of manufactured habitats could facilitate species spread throughout urban areas and into nearby natural waterbodies. We also conducted a survey of the severity of plant invasion in 30 ponds in Gainesville, FL, US across two pond types (dry vs. wet), and a gradient of management intensities (low, medium, high) and pond ages. We unexpectedly found a high number of invasive plant species (28 in just 30 ponds). Ninety-six percent of surveyed ponds contained from one to ten of these species, with ponds exhibiting high turnover in invader composition (i.e., high beta diversity). The bank sections of dry unmanaged ponds exhibited the highest mean invasive species richness (5.8 ± 1.3) and the inundated centers of wet medium managed ponds exhibited the highest mean invasive species cover (34 ± 12%). Invasive plant richness and cover also tended to be greater in dry ponds with higher soil nutrient levels, and in older wet ponds. Therefore, we found that highly maintained and younger wet ponds were the least invaded. Nevertheless, common management practices that limit plant invasions may also limit native species establishment and invasion may increase in the decades following pond construction.

Complex agroforestry systems against biotic homogenization: The case of plants in the herbaceous stratum of cocoa production systems

In addition to their potential against deforestation and climate change, agroforestry systems may have a relevant role in biodiversity conservation. In this sense, not only species richness per se, but also community composition, including the distribution range of the species, should be considered. The latter is especially relevant in the current context of biotic homogenization, where the presence of geographically widely distributed species is increasingly frequent in detriment of native species.By studying plant species of the herbaceous stratum of cacao production systems, we can evaluate, at a narrow local scale (>10 ha), the potential role of agroforestry systems and management intensity in diversity conservation and against biotic homogenization. This study was performed in an experimental trial in Bolivia, where five production systems representing a gradient of management intensity were compared: two monocultures and two agroforestry systems under conventional and organic farming containing a planted cover crop layer, and a complex successional agroforestry system with no external inputs. All species in the herbaceous stratum were identified and classified according to their geographical range. An indicator species analysis was implemented to identify species linked to a specific production system.In total, 171 species were recorded, 42% of which were strictly herbaceous while the rest of them were woody regrowths, mainly found in the successional agroforestry system (an average of 40 species compared to 16 species in the other systems). Total species richness was higher in the successional agroforestry system compared with the other production systems. No main differences were found between the other systems, that is, monocultures and conventionally managed systems did not have less species than agroforestry and organically managed systems. However, community composition did change following the management intensity gradient. In addition, we found that widely distributed species, including some exotic species, were associated to intensive management, i.e. monocultures and conventional systems with high solar exposure levels and/or glyphosate application. Conversely, successional agroforestry and organic systems harbored species with a geographical distribution range restricted to the Neotropics or South America. According to our results, promotion and support for the adoption of cocoa organic and agroforestry systems, as a counterbalance to the common intensively managed plantations, could contribute to both biodiversity conservation and the minimization of biotic homogenization.

Soil and landscape affecting technology transfer targeting subsistence farmers in central Tanzania

AbstractThis article deals with technology transfer from science to agriculture with pearl millet (Pennisetum glaucum(L.)R.Br.) in central Tanzania as example. The major question is which validity recommendations from different types of field experiments have and how geo-information (i.e. soil and landscape position) can lead to more site-specific recommendations. Tied ridging and reduced amounts of placed fertilizer during sowing were tested to increase yields on researcher-managed plots on-station, demonstration plots in villages, and farmer-managed plots on-farm. While on-station trials provided potential yield effects, physical distance to the station and differing conditions led to a higher informational value of village plots that mirror the context of local farmers. The treatments often resulted in significant yield increase. Soil and relief information and distance to settlements (i.e. gradient of management intensity) are key factors for data variability in on-farm trials. Unexplained variability is introduced through leaving degrees of freedom with respect to management to the farmer. Apart from soil and physiographic information, the latter should be part of a detailed data collection procedure in agronomic trials in large numbers addressing Sub-Saharan smallholder farming. Balanced data sets with dispersed trials on crucial soil and relief units are essential for future research.

Long-Term Abandonment of Forest Management Has a Strong Impact on Tree Morphology and Wood Volume Allocation Pattern of European Beech (Fagus sylvatica L.)

The three-dimensional (3D) morphology of individual trees is critical for light interception, growth, stability and interactions with the local environment. Forest management intensity is a key driver of tree morphology, but how the long-term abandonment of silvicultural measures impacts trunk and crown morphological traits is not fully understood. Here, we take advantage of a long management intensity gradient combined with a high-resolution terrestrial laser scanning (TLS) approach to explore how management history affects the 3D structure of mature beech (Fagus sylvatica L.) trees. The management gradient ranged from long-term (>50 years) and short-term (>20 years) unmanaged to extensively and intensively managed beech stands. We determined 28 morphological traits and quantified the vertical distribution of wood volume along the trunk. We evaluated the differences in tree morphological traits between study stands using Tukey’s HSD test. Our results show that 93% of the investigated morphological traits differed significantly between the study stands. Significant differences, however, emerged most strongly in the stand where forest management had ceased >50 years ago. Furthermore, we found that the vertical distribution of trunk wood volume was highly responsive between stands with different management intensity, leading to a 67% higher taper top height and 30% lower taper of beech trees growing in long-term unmanaged stands compared to those in short-term unmanaged or managed stands. These results have important implications for management intensity decisions. It is suggested that the economic value of individual beech trees from long-term unmanaged forests can be expected to be very high. This might also translate to beech forests that are extensively managed, but we found that a few decades of implementation of such a silvicultural system is not sufficient to cause significant differences when compared to intensively managed stands. Furthermore, TLS-based high-resolution analyses of trunk and crown traits play a crucial role in the ability to better understand or predict tree growth responses to the current drivers of global change.

Herbicides and herbivory interact to drive plant community and crop-tree establishment.

Land management practices often directly alter vegetation structure and composition, but the degree to which ecological processes such as herbivory interact with management to influence biodiversity is less well understood. We hypothesized that large herbivores compound the effects of intensive forest management on early seral plant communities and plantation establishment (i.e., tree survival and growth), and the degree of such effects is dependent on the intensity of management practices. We established 225-m2 wild-ungulate (deer and elk) exclosures, nested within a manipulated gradient of management intensity (no-herbicide control, light herbicide, moderate herbicide, and intensive herbicide treatments), replicated at the scale of whole harvest units (10-19ha). Vegetation structure, composition, and crop-tree responses to herbivory varied across the gradient of herbicide application during the first two years of stand establishment, with herbivory effects most evident at light and moderate herbicide treatments. In the moderate herbicide treatment, which approximates management applied to >2.5million hectares in the Pacific Northwest, United States, foraging by deer and elk resulted in simplified, low-cover plant communities more closely resembling the intensive herbicide treatment. Herbivory further suppressed the growth of competing vegetation in the light herbicide treatment, improving crop-tree survival, and providing early evidence of an ecosystem service. By changing community composition and vegetation structure, intensive forest management alters foraging selectivity and subsequent plant-herbivore interactions; initial shifts in early seral communities are likely to influence understory plant communities and tree growth in later stages of forest development.

Response of lepidopteran herbivore communities to crop management in coffee plantations

Although the conservation potential of low input coffee plantations has been widely proved, the effect of management intensity on insect herbivores and particularly caterpillar communities has been scarcely studied. We used a management intensity quantitative index to assess changes in leaf damage, abundance of all herbivores and caterpillar species richness, abundance, evenness and community species composition along a management intensity gradient in coffee plantations.There was no correlation between management intensity and the abundance of all herbivore guilds, but there was a negative relationship between management intensity and caterpillar abundance and species richness. Management intensity was positively related to caterpillar species evenness but did not influence species composition, which was rather influenced by climatic seasonality. We found 202 lepidopteran morphospecies, of which 128 fed on coffee plants. Despite a greater caterpillar abundance and richness, mean leaf damage to coffee plants was lower in plantations with a low management intensity index. Overall, we suggest that low and intermediate management intensity and the preservation of a diverse shade canopy can contribute to the conservation of Lepidoptera, without representing significant amounts of leaf damage to coffee plants.

Domestication and saponins contents in a gradient of management intensity of agaves: Agave cupreata, A. inaequidens and A. hookeri in central Mexico

Saponins occur in numerous plants, including agaves, determining benefic and harmful properties to humans; their presence may favor using plants as soap and other products, but also they may cause caustic effects producing contact dermatitis. In domestication, favorable and unfavorable properties of saponins may cause an increase or decrease of their content, respectively. This study quantified and identified saponins among wild and managed populations of three agave species: A. cupreata Trel. et Berger, A. inaequidens Koch with wild and cultivated populations used for mescal production, and A. hookeri Jacobi, existing exclusively cultivated, used for production of the fermented beverage pulque. We studied 272 plants from 19 populations, quantifying contents of crude saponins through spectrometry. In 12 populations, the saponins types were identified by High Performance Liquid Chromatography–Mass-Spectrography-Time-of-Flight HPLC-MS-TOF. The highest crude saponins content was recorded in A. hookeri (26.09 mg/g), followed by A. cupreata (19.85 and 15.17 mg/g in wild and cultivated populations, respectively). For A. inaequidens, we recorded 14.21, 12.95, and 10.48 mg/g in wild, silvicultural managed and cultivated populations, respectively. We identified 18 saponins types, A. inaequidens showing all of them. A hecogenin glycoside (HG1) is found in high amounts in A. hookeri but in low quantities in A. inaequidens and A. cupreata. A. inaequidens had the greatest diversity of saponins. The contents of crude saponins in A. inaequidens and A. cupreata decrease with management intensity, but contrarily to what we expected, it was the highest in A. hookeri. We hypothesize that such high amount could be due to some saponins, probably HG1, may be precursors of sugars.

Responses of the structure and function of the understory plant communities to precipitation reduction across forest ecosystems in Germany

Key messageUnderstory plant communities are essential for the recruitment of trees making up future forests. Independent of plant diversity, the understory across different forest ecosystems shows considerable physiological acclimation and structural stability towards drought events, which are expected to occur more frequently in future.ContextUnderstory plant communities are essential for the recruitment of trees making up the future forest. It is so far poorly understood how climate change will affect understory in beech and conifer forests managed at different intensity levels.AimsWe hypothesized that drought would affect transpiration and carbon isotope discrimination but not species richness and diversity. Moreover, we assumed that forest management intensity will modify the responses to drought of the understory community.MethodsWe set up roofs in forests with a gradient of management intensities (unmanaged beech—managed beech—intensively managed conifer forests) in three regions across Germany. A drought event close to the 2003 drought was imposed in two consecutive years.ResultsAfter 2 years, the realized precipitation reduction was between 27% and 34%. The averaged water content in the top 20 cm of the soil under the roof was reduced by 2% to 8% compared with the control. In the 1st year, leaf level transpiration was reduced for different functional groups, which scaled to community transpiration modified by additional effects of drought on functional group leaf area. Acclimation effects in most functional groups were observed in the 2nd year.ConclusionForest understory shows high plasticity at the leaf and community level, and high structural stability to changing climate conditions with drought events.

Changes in grassland management and plant diversity in a marginal region of the Carpathian Mts. in 1999–2015

The political change from socialism to democracy in countries of Central and Eastern Europe at the end of the 20th century induced broad changes in agriculture mostly due to land ownership changes and strong reduction of subsidies to agriculture. This resulted in agricultural decline, including grassland abandonment, which influenced grassland biodiversity and conservation. Between 1999 and 2015 we studied the grasslands in the area depopulated in the early 1980's in the Poloniny National Park (NE Slovakia, Carpathian Mts.). The aim of the study was to examine influence of environmental factors and grassland management driven by the Common Agricultural Policy (CAP) to plant community structure and taxonomical diversity. We identified altitude and soil properties as the main environmental factors: altitude determines climate gradient and probably also management intensity gradient and soil properties express soil fertility via A-horizon depth. We identified remarkable increase of proportion of managed grasslands from only 8% in 1999 to 40% in 2012–2015; other 7% of sampled grasslands were recently restored and prepared for future management. The average species richness in grasslands managed in 2012–2015 increased from 47.5 species per record in 1999 to 54.2 species in 2012–2015, the increase was found statistically significant. In 2012–2015, we observed statistically significant difference in the average species richness between managed (54.2) and abandoned grasslands (46.3). The agricultural subsidies of the CAP drive the grassland management in the study area. Therefore, we conclude that CAP enabled grassland biodiversity maintenance in significant part of the Poloniny National Park following start of its application in 2004 and above provided figures can be considered as indicators of the CAP effectiveness in our study area. However, the conservation of mountain meadows remains a challenge because of their poor accessibility.

How management intensity and neighborhood composition affect the structure of beech (Fagus sylvatica L.) trees

The intensity of silvicultural interventions and the neighborhood composition determine branching patterns, crown shape, and trunk attributes of beech ( Fagus sylvatica L.) trees. The intensity of silvicultural interventions and the composition of tree species are important forest management decisions. Both determine tree shape and thus influence the value of a tree, be it in terms of economy (trunk form, branchiness), or in terms of ecology (microhabitats). However, our knowledge on the distinct changes in tree architecture due to silvicultural management intensity or different neighborhood diversities is still limited, especially if the focus is on single tree attributes, e.g., branching patterns or crown shapes. We used terrestrial laser scanner data to calculate 25 structural measures for 55 European beech (Fagus sylvatica L.) trees that grew either in pure stands along a gradient of management intensity or in intra or interspecific neighborhoods in unmanaged stands. We found a lower height of maximal horizontal crown extension, a higher crown surface area, and straighter trunks with increasing management intensity. Moreover, our study revealed that beech trees surrounded by valuable hardwoods showed a lower height of maximal horizontal crown extension, a lower height–diameter ratio, and longer branches with flatter branch angles than beech trees surrounded by conspecific neighbors. Our findings provide evidence of phenotypic plasticity of European beech to diverse environmental conditions. The differences in tree structure indicate an increasing crown competition with decreasing management intensity and stronger competitive pressure for beech surrounded by conspecific neighbors in comparison to alien neighbors.

Canopy space filling rather than conventional measures of structural diversity explains productivity of beech stands

Silvicultural success in achieving, among other management goals, maximum productivity strongly depends on knowledge of the relationship between stand density and the resulting growth response of a stand. However, there are still controversial discussions whether wood production can be enhanced by silvicultural thinning or reaches its maximum in unmanaged forest stands if time plays no role. Moreover there is no universal answer whether structural diversity promotes or reduces productivity. In the present study we applied terrestrial laser scanning (TLS) to investigate the relationship between three-dimensional space filling, forest management intensity, productivity and conventional measures of structural diversity. We examined 35 beech-dominated forest plots along a gradient of management intensity in three regions of Germany. We found that space filling in leaf-on condition increased with management intensity, particularly in the shaded crown. Increased space filling in the shaded crown due to tree removals also resulted in higher stand productivity. We conclude that an increased space filling in the shaded canopy of managed European beech stands is responsible for the compensation of production losses in the upper canopy due to thinning activities. Conventional measures of structural diversity were not sensitive to the applied silvicultural activities. We also found no relationship between structural diversity described by conventional measures and stand productivity.

Soil microbial community responses to long-term land use intensification in subtropical grazing lands

Land use intensification often results in modification in plant cover and nutrient inputs with subsequent potential effects on composition and structure of soil microbial community and fractions. The objective of this study was to understand the long-term (>22yr) impacts of land use intensification (introduction of productive vegetation type, greater N fertilizer input and stocking rate) on soil microbial community composition and activity in Florida grazing lands. Experimental sites consisted of a gradient of management intensities ranging from native rangeland (lowest), silvopasture (intermediate), to sown pasture (highest). Increasing management intensity from native rangeland to sown promoted microbial biomass and activity. At the 0–10cm, soil microbial biomass carbon (MBC) concentration was greater in sown pasture (334mgkg−1) compared to silvopasture and native rangeland (193 and 232mgkg−1, respectively). Similarly, potentially mineralizable C (PMC) increased in response to grazing land intensification (1.2mg CO2-C kg−1d−1 for sown pastures vs. 0.5 and 0.6mg CO2-C kg−1d−1 for native rangeland and silvopasture, respectively). Sown pastures exhibited the greatest levels of β-glucosidase activity (203nmolg−1 soil h.−1) and phospholipid fatty acid (PLFA) biomass (222μmolkg−1 soil) compared to native rangeland and silvopasture. Results also demonstrated greater relative abundance of bacteria and less fungi as land use intensification increased from native rangeland to silvopasture or sown pasture. Our study indicated that long-term land use intensification affected the size, activity, and composition of soil microbial community in subtropical grazing lands.

Converting exotic forages to native warm-season grass can increase avian productivity in beef production systems

Grasslands are among the most imperiled ecosystems in the world, and establishment of exotic forage grasses and management for uniform utilization may have contributed to population declines of many obligate grassland bird species in North America. Native warm-season grasses (NWSG) are increasingly promoted as viable alternatives to exotic forages currently in production such as bermudagrass (Cynodon dactylon) and tall fescue (Schedonorus arundinaceus), but structure of native bunchgrasses also may offer nesting habitat for birds such as the dickcissel (Spiza americana). Establishing NWSG pastures may thereby create an opportunity for land-sharing, where agriculture incorporates biodiversity-friendly practices. We investigated dickcissel responses to NWSG and grazing at the Prairie Research Unit in Monroe Co., Mississippi (USA), where we established a gradient of management intensity among four treatments in small, operational-scale pastures (6.4–10.5ha). Treatments included grazed exotic forages, two grazed NWSG treatments including Indian grass (Sorghastrum nutans) monoculture and grazed mixed NWSG polyculture of Indian grass, little bluestem (Schizachyrium scoparium), and big bluestem (Andropogon gerardii), and a non-grazed NWSG polyculture treatment. We applied a multi-state capture-recapture model in a Bayesian framework to estimate dickcissel nest density and productivity while accounting for nest stage-specific variation in survival and detection. Nest density and productivity were consistently greater in non-grazed NWSG than grazed exotic pasture, whereas productivity in grazed NWSG treatments was intermediate but declined between years. We also found that variation in survival and density did not always correspond with estimated productivity, and thus solely relying on either parameter may be misleading when making inferences on habitat quality. These results suggest a positive response to NWSG among dickcissels in this system, but grazing may reduce nest site abundance, and consequently productivity. Native warm-season forages may be a viable land-sharing alternative by increasing productivity of tall structure specialists such as dickcissels compared with exotic grass pastures currently in production, but grazing should be managed to ensure abundance of tall vegetation structure for nest sites.

Farmland biodiversity and agricultural management on 237 farms in 13 European and two African regions.

Farmland is a major land cover type in Europe and Africa and provides habitat for numerous species. The severe decline in farmland biodiversity of the last decades has been attributed to changes in farming practices, and organic and low-input farming are assumed to mitigate detrimental effects of agricultural intensification on biodiversity. Since the farm enterprise is the primary unit of agricultural decision making, management-related effects at the field scale need to be assessed at the farm level. Therefore, in this study, data were collected on habitat characteristics, vascular plant, earthworm, spider, and bee communities and on the corresponding agricultural management in 237 farms in 13 European and two African regions. In 15 environmental and agricultural homogeneous regions, 6-20 farms with the same farm type (e.g., arable crops, grassland, or specific permanent crops) were selected. If available, an equal number of organic and non-organic farms were randomly selected. Alternatively, farms were sampled along a gradient of management intensity. For all selected farms, the entire farmed area was mapped, which resulted in total in the mapping of 11338 units attributed to 194 standardized habitat types, provided together with additional descriptors. On each farm, one site per available habitat type was randomly selected for species diversity investigations. Species were sampled on 2115 sites and identified to the species level by expert taxonomists. Species lists and abundance estimates are provided for each site and sampling date (one date for plants and earthworms, three dates for spiders and bees). In addition, farmers provided information about their management practices in face-to-face interviews following a standardized questionnaire. Farm management indicators for each farm are available (e.g., nitrogen input, pesticide applications, or energy input). Analyses revealed a positive effect of unproductive areas and a negative effect of intensive management on biodiversity. Communities of the four taxonomic groups strongly differed in their response to habitat characteristics, agricultural management, and regional circumstances. The data has potential for further insights into interactions of farmland biodiversity and agricultural management at site, farm, and regional scale.

Patch patterns of lowland beech forests in a gradient of management intensity

Forest development phases (FDPs) represent patches that are in different stages of the forest life cycle as conceived in the shifting mosaic concept. FDPs are a widely used framework to describe forest stand structure and dynamics. Natural forests are characterized by small patch sizes, a full set of FDPs and a large vertical heterogeneity which is considered crucial for their biodiversity. Forest management approaches that promote such characteristics of high naturalness are increasingly recommended for biodiversity conservation. Here we investigate the effect of a 10-year naturalness-promoting management regime on forest stand structure, expressed through different patterns in FDP structure and composition.We studied 22 beech forest stands in north-eastern Germany that are managed in two different ways (naturalness-promoting management and other management) or that have been unmanaged for varying periods of time (recently, 20–35years and long-term, 65 to more than 100years). FDPs were investigated in 2012/13 across the total area of the study sites (714ha). The FDP assignment is based on a dichotomic decision tree with variables such as diameter at breast height, canopy cover, deadwood amount, regeneration cover and tree height. We analyzed FDP patch size, aggregation and mean minimum distance between patches of the same FDP and structural evenness of FDP proportions.For stands with naturalness-promoting management we found that: (1) there are different FDP proportions, FDP patch sizes and distances between patches of the same FDP compared to the other three management types; (2) there are significant differences in comparison to long-term unmanaged stands in terms of the aggregation indices of the initial phase, optimum phases and the disintegration phase; (3) these stands have the highest aggregation of the regeneration phase, which differs significantly from the other management types; and (4) they contain a similar FDP distribution to that in natural beech forests.In conclusion, naturalness-promoting management supports small-scale patch heterogeneity and maintains forest structure and life cycle that are closer to natural and unmanaged stands compared to other management types.