Soil as a Critical Component of Vegetation Restoration on a Sub‐Alpine Mountain Summit in Acadia National Park

Effects of different management practices on soil conservation and soil water in a rainfed olive orchard

Intensive, large‐scale agriculture promotes the conversion of natural habitats and diversified crops into monocultures, decreasing both native vegetation cover and landscape heterogeneity, leading to landscape simplification. Yet, a key knowledge gap persists on the relative impacts of the loss of native vegetation and landscape heterogeneity on biodiversity. Addressing this gap is pressing to support policies that conciliate agricultural production and biodiversity conservation and to move forward some scientific controversies, as the ‘land sharing versus land sparing’ and ‘habitat loss versus fragmentation’ debates. Through a hierarchical sampling design that maximised variation, while minimising correlation, between landscape heterogeneity and native vegetation cover, we recorded the occurrence of medium and large‐bodied mammals in native vegetation and agricultural areas of 55 landscapes in a global conservation hotspot and a key commodity production area—the Brazilian Savanna, Cerrado. We compared simple, additive and interactive models to investigate the effects of landscape heterogeneity and native vegetation cover on richness and composition of native and invasive mammals. Native and invasive mammal communities were affected by both native vegetation cover and landscape heterogeneity, although the effects of the first was stronger than the later. Both aspects had positive effects on native species richness and negative effects on invasive species richness, indicating that the loss of native vegetation and the reduction in landscape heterogeneity lead to biotic homogenisation. Yet, while landscape heterogeneity benefited most native species, the direction of its effect varied among invasive species and depended on native vegetation cover. Synthesis and applications. Besides reducing habitat loss, avoiding landscape homogenisation is key for conciliating agricultural production and biodiversity conservation, pointing to the relevance of policies encouraging crop diversification. As increasing landscape heterogeneity can in part compensate the negative effects of losing native habitat on biodiversity in agroecosystems, policies can gain feasibility by adjusting the balance between native vegetation cover and landscape heterogeneity according to what best suits local restraints and demands.

Context The replacement of native vegetation by exotic grasses for livestock production is driving landscape homogenization, habitat fragmentation and reducing connectivity between habitat patches in floodplains ecosystems. Objective In this context we examined how changes in native and exotic vegetation cover, connectivity and water depth affect the attributes of the small [standard length (SL)\80 mm as adults] and large-sized fish assemblages (SL C 80 mm as adults). Method We assessed the effects of water depth, exotic and native vegetation cover and habitat connectivityonthe abundance, species richness, body size andbiomassoffishassemblagesina25 km 2 areaofthe seasonal habitats of the Pantanal wetland over 5 years. Results We showed that fish assemblage response to meso-scale variation in water depth, vegetation cover and habitat connectivity in seasonal habitats is sizedependent. The gradient from exotic to natural vegetation cover did not affect the assemblages of small-sized fish,whichweremostlyregulatedbywaterdepth,habitat connectivity and the gradient from grassland to forest. However, besides being affected by water depth and habitat connectivity, large-sized fish were also affected by the gradient from exotic to natural vegetation cover. Conclusion Our results indicate that transformations in the landscape and changes in the dynamics of inundation may have negative consequences for the long-term persistence of fish assemblages in the Pantanal wetlands.

Science and Public Engagement in National Parks: Examples and Advice from Young Scientists

Soil depth, plant rooting strategies and species’ niches

Human influence on the environment is so extensive that virtually all ecosystems on the planet are now affected by biological invasions. And, often, ecosystems are invaded by multiple co‐occurring non‐native species. Hence, it is important to understand the impacts these invasions are producing on biodiversity and ecosystem processes.Here, we present results of a 2‐year long field experiment where we tested the effects of co‐occurring invasive C4African grasses in a Cerrado area in central Brazil. We compared plant and arthropod communities, plant biomass, and soil nitrogen dynamics and soil chemical characteristics across five experimental treatments:Urochloa decumbensremoval;Melinis minutifloraremoval; bothU.decumbensandM.minutifloraremoval;U.decumbensandM.minutiflorainvaded plots; and uninvaded Cerrado. We hypothesized that selective removal of invasive grasses would have distinct effects on the native ecosystem structure and functioning. We expected that each invasive grass would produce a different type of impact on the native ecosystem and that their impacts would be synergistic when co‐occurring.Removal ofM.minutifloradoubled native plant diversity and biomass when compared to invaded plots, whereas removal ofU.decumbensdid not alter these parameters. Cerrado plots had four times more plant species than plots cleared of invasives. Removal of invasive grasses did not affect the species richness or community composition of soil epigeal fauna. Cerrado soils had lower fertility, organic matter content and pH than invaded soils. The effects were generally higher when both invasive grasses were removed, suggesting impacts were synergistic, butM.minutiflorahad greater effects on plants and soils thanU.decumbens. Both invasive species produced negative impacts, but a single species was the main driver. We also detected persistent effects of the invasive grass species on the ecosystem after 2 years of removal.We conclude that invasive species of the same functional group have similar types of effects in native ecosystems, but the magnitude of impact was largely dependent on invasive species biomass and cover. Where multiple invasive species are present, research and management of invaded ecosystems should tackle the interacting effects of co‐occurring invaders.

The effect of land use change on soils and vegetation over various lithological formations on Lesvos (Greece)

Interannual variation in soybean yield: interaction among rainfall, soil depth and crop management

Vegetation development following a local summer storm in 1997 was studied in windthrown beech (Fagus sylvatica) forests on base-rich Zechstein sites (gypsum karst and dolomitic limestone) as well as on acidic Bunter Sandstone in the foothills of the Harz Mountains (southern Lower Saxony) from 1998 through 2001. Plant succession and natural reforestation of these stands are discussed relative to site conditions (base-rich vs. acidic and deep vs. shallow soils), intensity of initial disturbance (unthrown stands, gaps, extensively thrown stands), previous forest management (managed stands vs. natural forests) and current treatment or lack thereof (abandoned windthrown vs. artificially afforested plots). After four years, all extensively windthrown stands were characterised by steadily increasing numbers of species. Base-rich stands showed a higher species diversity than acidic, artificially afforested plots were more diverse than abandoned, and stands on shallow soils contained more species than those on deep. All stands except those on shallow gypsum karst showed a strong expansion of the shrub layer while the field layer stagnated or slightly decreased. The following trisection could be worked out by analysing functional species groups on extensively thrown stands: 1. Base-rich, deep soils on dolomitic limestone (e.g. Hordelymo-Fagetum): dominance of forest floor species and a very individual-rich natural regeneration of the climax trees (mostly Fraxinus excelsior, further more Fagus sylvatica and Acer pseudoplatanus). 2. Base-rich, shallow soils on gypsum karst (e.g. Carici-Fagetum): stands are covered by increasing pioneer vegetation (especially herbs of the Artemisietea and Epilobietea); the population density of the natural regeneration is medium-ranged and includes Fraxinus excelsior, Fagus sylvatica, Acer pseudoplatanus, A. platanoides, Ulmus glabra and Tilia platyphyllos. 3. (More or less) Acidic soils on Bunter Sandstone (e.g. Galio odorati-, Luzulo-Fagetum): pioneer shrubs dominate (mostly Rubus idaeus, further more Sambucus racemosa, S. nigra and Rubus fruticosus agg.); the population density of natural regeneration is relatively low and dominated by Fagus sylvatica. Pioneer trees such as Betula pendula or Salix caprea hardly occured until after four years following the windthrow. Typical Querco-Fagetea species were nowhere outcompeted. Even on gypsum karst and Bunter Sandstone the forest floor species perennate under different types of pioneer vegetation and keep constant or partly increasing absolute coverages. Especially on acidic soils the course of natural vegetation depends upon the severity of disturbance. The larger the disturbed area, the more the pace of natural reforestation toward a climax community is retarded and pioneer vegetation becomes dominant. Beech sapling number and percentual share of the climax species Fagus sylvatica, strongly decrease along a gradient from unthrown stands over gaps to large disturbed areas. In small windthrown gaps, natural regeneration of beech seems to be secure, but in extensively windthrown stands the initially established shrubs outcompete the beech. In opposition to this, natural reforestation on base-rich, deep soils proceeds very rapidly and seems to be independently from the severity of disturbance. Here, natural regeneration of the climax trees and the old forest floor vegetation dominate even under conditions of large scale windthrow. The vegetation development on shallow gypsum karst stands probably represents an intermediate successional pathway. Plant succession on root plates of uprooted trees caused a (especially quantitative) floristic adjustment between these microsites and the surrounding plot which proceeded faster on shallow than on deep soils. On deep (productive) soils root plates were preferred by light indicating species and pioneer vegetation that increased their coverages stronger here than on the surrounding plot. On shallow (less productive) soils a nearly identical development on both subsites could be observed. Although one third of the whole species pool did not occur on root plates, an analysis of functional species groups showed no qualitative differences between these microsites and their surrounding and further more stable spectra within the first four years of succession on both subsites. A site-dependent gradient of natural regeneration from base-rich to acidic conditions can be shown. The more base-rich the substrate, the faster and more independently from severe extrorse disturbance natural reforestation proceeds. Among all investigated stands, beech forests on base-rich, deep soils show the most resilient response to natural disturbance. A complete species-change can´t be confirmed for Central European beech forests growing in their optimal phase. Succession in these forest communities doesn´t involve major species changes but rather temporal changes of dominance of residual species. A replacement of the typical beech forest communities caused by windthtrow can´t be expected - neither in the investigated nor in comparable areas.

Livestock grazing in riparian areas has significant impacts on waterway ecosystems. In Australia, livestock grazing is allowed on many public waterway frontages under long-term licences. Many barriers to removing or restricting grazing on riparian areas exist, including concerns that removing grazing from historically grazed sites may favour invasive plant species. We compared vegetation changes at 180 sites along three connected waterways in northern Victoria, Australia that had been extensively grazed by livestock under grazing licences. Some of these sites were permanently protected from grazing by the creation of a new public park and reserve system in 2002. We compared vegetation attributes between sites in the ungrazed reserves, to sites outside reserves that were either recently grazed or ungrazed in 2009. Importantly, we used a sampling design and statistical models that explicitly incorporated the proximity to the waterway to account for known resource and disturbance gradients. Broad site condition assessments that were conducted on the exact same sites prior to reservation provided an indication of pre-treatment condition attributes. Despite no clear evidence of having more or less native vegetation prior to reservation, reserved sites had more native vegetation cover across a range of different life-form types than unreserved sites. Reserved sites also had much less bare ground, and this effect was far greater closer to the waterway margin. Livestock grazing within reserves reduced these perceived benefits for native vegetation and bare ground. However, reserved sites also had a higher cover of exotic graminoids, but not herbs. This study suggests that reservation of stream frontages was beneficial to native vegetation condition within the study systems even if grazing persisted. Livestock grazing was effective at reducing exotic vegetation cover but at the cost of native vegetation and ground condition. Many factors may influence outcomes and we expect these responses to differ in more productive landscapes or in periods with greater rainfall, so quantitative monitoring is advisable. Evaluation of cost-benefit trade-offs for the environment, graziers, and social and cultural objectives will be important to guide reservation decisions. • Livestock grazing increases bare ground and reduces native vegetation cover. • Reservation decreases bare ground and increases native vegetation cover. • Removal of grazing increased exotic vegetation cover. • Bare ground and vegetation cover vary with proximity to a waterway. • Livestock grazing pressure and impacts vary with proximity to a waterway.

We used multiscale plots to sample vascular plant diversity and soil characteristics in and adjacent to 26 long-term grazing exclosure sites in Colorado, Wyoming, Montana, and South Dakota, USA. The exclosures were 7–60 yr old (31.2 ± 2.5 yr, mean ± 1 se). Plots were also randomly placed in the broader landscape in open rangeland in the same vegetation type at each site to assess spatial variation in grazed landscapes. Consistent sampling in the nine National Parks, Wildlife Refuges, and other management units yielded data from 78 1000-m2 plots and 780 1-m2 subplots. We hypothesized that native species richness would be lower in the exclosures than in grazed sites, due to competitive exclusion in the absence of grazing. We also hypothesized that grazed sites would have higher native and exotic species richness compared to ungrazed areas, due to disturbance (i.e., the intermediate-disturbance hypothesis) and the conventional wisdom that grazing may accelerate weed invasion. Both hypotheses were soundly rejected. Although native species richness in 1-m2 subplots was significantly higher (P < 0.05) in grazed sites, we found nearly identical native or exotic species richness in 1000-m2 plots in exclosures (31.5 ± 2.5 native and 3.1 ± 0.5 exotic species), adjacent grazed plots (32.6 ± 2.8 native and 3.2 ± 0.6 exotic species), and randomly selected grazed plots (31.6 ± 2.9 native and 3.2 ± 0.6 exotic species). We found no significant differences in species diversity (Hill’s diversity indices, N1 and N2), evenness (Hill’s ratio of evenness, E5), cover of various life-forms (grasses, forbs, and shrubs), soil texture, or soil percentage of N and C between grazed and ungrazed sites at the 1000-m2 plot scale. The species lists of the long-ungrazed and adjacent grazed plots overlapped just 57.9 ± 2.8%. This difference in species composition is commonly attributed solely to the difference in grazing regimes. However, the species lists between pairs of grazed plots (adjacent and distant 1000-m2 plots) in the same vegetation type overlapped just 48.6 ± 3.6%, and the ungrazed plots and distant grazed plots overlapped 49.4 ± 3.6%. Differences in vegetation and soils between grazed and ungrazed sites were minimal in most cases, but soil characteristics and elevation were strongly correlated with native and exotic plant diversity in the study region. For the 78 1000-m2 plots, 59.4% of the variance in total species richness was explained by percentage of silt (coefficient = 0.647, t = 5.107, P < 0.001), elevation (coefficient = 0.012, t = 5.084, P < 0.001), and total foliar cover (coefficient = 0.110, t = 2.104, P < 0.039). Only 12.8% of the variance in exotic species cover (log10cover) was explained by percentage of clay (coefficient = −0.011, t = −2.878, P < 0.005), native species richness (coefficient = −0.011, t = −2.156, P < 0.034), and log10N (coefficient = 2.827, t = 1.860, P < 0.067). Native species cover and exotic species richness and frequency were also significantly positively correlated with percentage of soil N at the 1000-m2 plot scale. Our research led to five broad generalizations about current levels of grazing in these Rocky Mountain grasslands: (1) grazing probably has little effect on native species richness at landscape scales; (2) grazing probably has little effect on the accelerated spread of most exotic plant species at landscape scales; (3) grazing affects local plant species and life-form composition and cover, but spatial variation is considerable; (4) soil characteristics, climate, anddisturbances may have a greater effect on plant species diversity than do current levels of grazing; and (5) few plant species show consistent, directional responses to grazing or cessation of grazing.

We used multiscale plots to sample vascular plant diversity and soil characteristics in and adjacent to 26 long-term grazing exclosure sites in Colorado, Wyoming, Montana, and South Dakota, USA. The exclosures were 7–60 yr old (31.2 ± 2.5 yr, mean ± 1 se). Plots were also randomly placed in the broader landscape in open rangeland in the same vegetation type at each site to assess spatial variation in grazed landscapes. Consistent sampling in the nine National Parks, Wildlife Refuges, and other management units yielded data from 78 1000-m2 plots and 780 1-m2 subplots. We hypothesized that native species richness would be lower in the exclosures than in grazed sites, due to competitive exclusion in the absence of grazing. We also hypothesized that grazed sites would have higher native and exotic species richness compared to ungrazed areas, due to disturbance (i.e., the intermediate-disturbance hypothesis) and the conventional wisdom that grazing may accelerate weed invasion. Both hypotheses were soundly rejected. Although native species richness in 1-m2 subplots was significantly higher (P < 0.05) in grazed sites, we found nearly identical native or exotic species richness in 1000-m2 plots in exclosures (31.5 ± 2.5 native and 3.1 ± 0.5 exotic species), adjacent grazed plots (32.6 ± 2.8 native and 3.2 ± 0.6 exotic species), and randomly selected grazed plots (31.6 ± 2.9 native and 3.2 ± 0.6 exotic species). We found no significant differences in species diversity (Hill’s diversity indices, N1 and N2), evenness (Hill’s ratio of evenness, E5), cover of various life-forms (grasses, forbs, and shrubs), soil texture, or soil percentage of N and C between grazed and ungrazed sites at the 1000-m2 plot scale. The species lists of the long-ungrazed and adjacent grazed plots overlapped just 57.9 ± 2.8%. This difference in species composition is commonly attributed solely to the difference in grazing regimes. However, the species lists between pairs of grazed plots (adjacent and distant 1000-m2 plots) in the same vegetation type overlapped just 48.6 ± 3.6%, and the ungrazed plots and distant grazed plots overlapped 49.4 ± 3.6%. Differences in vegetation and soils between grazed and ungrazed sites were minimal in most cases, but soil characteristics and elevation were strongly correlated with native and exotic plant diversity in the study region. For the 78 1000-m2 plots, 59.4% of the variance in total species richness was explained by percentage of silt (coefficient = 0.647, t = 5.107, P < 0.001), elevation (coefficient = 0.012, t = 5.084, P < 0.001), and total foliar cover (coefficient = 0.110, t = 2.104, P < 0.039). Only 12.8% of the variance in exotic species cover (log10cover) was explained by percentage of clay (coefficient = −0.011, t = −2.878, P < 0.005), native species richness (coefficient = −0.011, t = −2.156, P < 0.034), and log10N (coefficient = 2.827, t = 1.860, P < 0.067). Native species cover and exotic species richness and frequency were also significantly positively correlated with percentage of soil N at the 1000-m2 plot scale. Our research led to five broad generalizations about current levels of grazing in these Rocky Mountain grasslands: (1) grazing probably has little effect on native species richness at landscape scales; (2) grazing probably has little effect on the accelerated spread of most exotic plant species at landscape scales; (3) grazing affects local plant species and life-form composition and cover, but spatial variation is considerable; (4) soil characteristics, climate, anddisturbances may have a greater effect on plant species diversity than do current levels of grazing; and (5) few plant species show consistent, directional responses to grazing or cessation of grazing.

The primary objective of this study was to detect vegetation disturbance resulting from visitor use by using remote sensing. A pre-classification change detection analysis based on the normalized difference vegetation index was utilized to measure the amount of vegetation cover changes at Cadillac Mountain summit, Acadia National Park, Maine. By analyzing new remote sensing data collected in 2010 and 2018, we compared the vegetation conditions at the summit (experimental site) with a nearby site with little or no visitor use (control site). Additionally, the study was designed to examine vegetation cover changes between 2001–2007 (the first time frame) and 2010–2018 (the second time frame). Similar to the results observed in the first time frame, the experimental and control sites exhibited more vegetation increase than vegetation decrease in the second time frame. The amount of vegetation increase was 1,425m2 at the experimental site and 400m2 at the control site. The amount of vegetation decrease was 150m2 at the experimental site and 75m2 at the control site. Measurable vegetation cover changes based on the remote sensing analysis could provide baseline data for monitoring further changes over an extended period of time. The advantages of using remote sensing in detecting vegetation conditions are also discussed, along with management and research implications. Keywords: remote sensing, recreation ecology, vegetation, visitor impact monitoring, parks and protected areas

Agricultural environments have a critical role in the global conservation of biodiversity, but the persistence of forest and woodland-dependent species in these systems is often limited by insufficient habitat. Modified or semi-natural ‘countryside’ (matrix) vegetation is used by many species, but its value at the landscape scale is rarely tested. Do such habitats simply provide additional resources for populations sustained by remnant native vegetation in the landscape, or can they enhance populations over and above that sustained by natural vegetation cover? We surveyed woodland-dependent birds in all types of landscape element in 27 farmland mosaics (100 ha each) in south-eastern Australia. Four measures of wooded vegetation cover were quantified: native vegetation only; and combinations of native vegetation plus scattered trees and/or tree plantations. We used an information-theoretic approach to compare the responses of 30 species to each measure of vegetation cover. Woodland birds were well represented in agricultural mosaics (65% of the regional species-pool); however, almost half were recorded only in mosaics with >20% native vegetation cover. The incidence of 23 species was positively related to measures of wooded cover, indicating increased occurrence in mosaics with a greater cover of wooded vegetation. For 12 species, scattered trees and plantations provided supplementary habitat that enhanced their population status at the landscape scale, beyond that sustained by native vegetation cover. While native vegetation has a critical role for conservation in agricultural environments, careful management of wooded countryside elements (such as scattered trees, tree plantations) offers additional benefits to the woodland-dependent avifauna.

Mediterranean ecosystems are predicted to undergo longer and more intense summer droughts. The mechanisms underlying the response of herbaceous communities to such drier environments should be investigated to identify the resilience thresholds of Mediterranean rangelands. A 5-year experiment was conducted in deep and shallow soil rangelands of southern France. A rainout shelter for 75 days in summer imposed drier and warmer conditions. Total soil water content was measured monthly to model available daily soil water. Aboveground net primary production (ANPP), forage quality, and the proportion of graminoids in ANPP were measured in spring and autumn. Plant senescence and plant cover were assessed in summer and spring, respectively. The experimental years were among the driest ever recorded at the site. Therefore, manipulated summer droughts were drier than long-term ambient conditions. Interactions between treatment, community type, and experimental year were found for most variables. In shallow soil communities, spring plant cover decreased markedly with time. This legacy effect, driven by summer plant mortality and the loss of perennial graminoids, led to an abrupt loss of resilience when the extreme water stress index exceeded 37 mm 10 day-1, characterized by a reduction of spring plant cover below 50% and a decreased ANPP in rainy years. Conversely, the ANPP of deep soil communities remained unaffected by increased summer drought, although the presence of graminoids increased and forage nutritive value decreased. This study highlights the role of the soil water reserve of Mediterranean plant communities in modulating ecosystem responses to chronically intensified summer drought. Communities on deep soils were resilient, but communities on shallow soils showed a progressive, rapid, and intense degradation associated with a loss of resilience capacity. Notably, indexes of extreme stress were a better indicator of tipping points than indexes of integrated annual stress. Considering the role of soil water availability in other herbaceous ecosystems should improve the ability to predict the resilience of plant communities under climate change.