Salix Cinerea Research Articles

Selective Foraging on Tree and Shrub Species by the European Beaver Castor fiber in Lowland and Highland Habitats in Western Poland

In this study, generic composition of food and foraging preferences of the European beaver were determined on sites where the beavers were reintroduced after more than 200 years of absence. Research area was located on lowland (Silesian Lowland) and highland habitats (Bystrzyckie Mountains, Wałbrzyskie Mountains) in western Poland. During the study period, 17,418 trees and shrubs growing within the feeding area of the beavers were marked, out of which 4,669 were found to be cut by beavers. The results showed that the foraging preferences of beavers depend on the availability and diversity of the local food sources. In the lowlands beavers preferred the following species of trees and shrubs as their primary food source: Salix cinerea, S. fragilis, S. caprea, Cornus sanguinea and Populus tremula. In the highlands, beavers preferred Corylus avellana, Sorbus aucuparia, and Fagus sylvatica due to the low availability of Salix and Populus species. Moreover, in the highlands, beavers had to cover longer distances to reach the feeding sites and had to cut trees with larger diameter than in the lowlands.

Can aerial herbicide application control Grey Willow (Salix cinerea L.) and stimulate native plant recovery in New Zealand wetlands?

SummaryGrey Willow (Salix cinerea L.) poses a significant threat to wetland ecosystems in New Zealand. To manage the ecological impacts and to control further spread, cost‐effective large‐scale control methods are needed. We investigated the response of Grey Willow and dominant wetland plant groups to the aerial boom‐spray application of glyphosate at 9 L/ha and triclopyr (amine) at 18 L/ha at three New Zealand wetlands. We found glyphosate substantially reduced the dominance of tall (>2 m) Grey Willow with commensurate increases in the dominance of most native plant groups. Triclopyr (amine) application resulted in poor Grey Willow control, was not associated with increased native plant group dominance, and some native plant groups declined where triclopyr (amine) was applied. We conclude that the aerial application of glyphosate is an effective large‐scale Grey Willow control tool and could be used to initiate the restoration of native plant communities in wetlands dominated by Grey Willow. But, evidence of Grey Willow recovery after control suggests that increases in native plant dominance will be reversed as Grey Willow re‐establish. Further research is needed to determine how to maintain and enhance native plant dominance after control, and to determine how to manage Grey Willow in fen areas where the Grey Willow canopy is discontinuous and nontarget herbicide impacts can occur. The aerial boom‐spray application of triclopyr (amine) for large‐scale Grey Willow control should be discontinued as it does not provide effective control and results in negative ecological outcomes.

Analysis of trophic structure of forest flora in the Oril River valley

Biodiversity is important for maintaining of forest ecosystems functioning and in their resistance to anthropo-climatic challenges. Assessment of species diversity and species ecomorphic analysis is the basis for determining their current status, rational use and protection. At the end of the nineteenth century, Belgard A. L. (1950) in his system of ectomorphs using terminology presented by Dekandol (1956) and Warming (1903), had proposed a «trophomorph» category that reflected species relation to soil richness. Analysis of trophomorphs reflects diversity of soil conditions in different biotopes within forest ecosystems. The article gives an analysis on vascular plant trophomorphs distribution in various forest biotopes of Oril river valley. Flora and vegetation surveys in forests of Oril river valley were carried out by A. L. Belgard and T. F. Kirichenko since the 30s of the 20th century. The latest data on forest vegetation state within the Oril river valley were given in the works of Y. Gamulja and V. Manyuk. Generalized bioecological analysis of flora Oril river valley was represented in the monograph of B. Baranovsky, V. Maniuk, I. Ivanko, L. Karmyzova «Flora analysis of the Oril National Park». As is known, edaphic conditions of plant habitats in a first place are determined by soil fertility depending on the plant nutrients availability. Soddy-forest soil on sandy terrace of Oril river valley has a relatively low content of humus and total nitrogen: 2 and 0.04 %. Under these conditions, pine phytocenoses were ocсurred that represented exclusively by artificial plantings. Soils in the depressed area of Oril river floodplain are much richer in humus and nitrogen content (10 and 0.37 %). Here, arboreal and shrubby vegetation is represented by communities with common oak. On the second terrace of Oril river valley, forest vegetation is represented by artificial pine forests. Microcenoses with black locust, amorpha and willow occurred on elevated areas of sandy terrace (arena). In the depressed area of the arena, microcenoses with aspen and birch, aspen, Tatarian maple, amorpha, black locust were occurred additionally to pine communities. In the Oril floodplain, native arboreal and shrubby vegetation is represented mainly by communities with common oak. In depressed areas of the floodplain, microcenoses with white poplar, black poplar, aspen, Tatarian maple, amorpha, willow (Salix alba, S. fragilis), osiery (Salix cinerea, S. triandra), and alder are fragmentarily occurred. In conditions of elevated areas of the floodplain, 196 vascular plants species were found, and 105 species in depressed areas. On the second terrace, 38 plant species grow on the elevated areas, and 54 species on the depressed ones. Flora includes 45 adventive plant species. In depressed floodplain areas, oligotrophs are represented by 7 species, mesotrophs by 126 species, megatrophs by 50 species, and in elevated areas: 7, 126 and 25 species, respectively. In depressed areas of arena oligotrophs are represented by 4 species, mesotrophs by 29 species, and megatrophs by 11, elevated areas: 7 and 21 species respectively, and megatrophs were absent.

Application of methyl jasmonate to grey willow (Salix cinerea) attracts insectivorous birds in nature

It has been suggested that insectivorous birds may be guided by herbivore-induced plant volatiles (HIPVs) to herbivore-rich trees with herbivorous damage. The HIPV production in plants is partly mediated by jasmonic acid signalling pathway. Methyl jasmonate (MeJA) was proved to be a suitable agent for induction of HIPVs similar to those induced by herbivorous insects in many plant species. We studied the effects of methyl jasmonate on volatile emission and natural enemy attraction using mature grey willow (Salix cinerea) under natural conditions in Czech Republic. We treated 12 experimental shrubs with 30 mM MeJA and completed the experiment with 12 control shrubs. We monitored attacks by natural predators with artificial plasticine caterpillars which were checked daily. Birds most often pecked the caterpillars exposed on MeJA-treated shrubs and this attractiveness differed significantly from control. Attractiveness of MeJA-treated shrubs did not differ significantly from control shrubs for arthropod predators. Spraying MeJA on grey willows resulted in significantly higher production of α-pinene, β-pinene, 3-carene, limonene and β-ocimene. There was a marginally significant positive correlation between the predation rate by birds and relative change in α-pinene emissions.

Glyphosate redirects wetland vegetation trajectory following willow invasion

AbstractAimsAerially applied glyphosate is an economic tool to deal with large areas of invasive plants. However, there are few studies investigating non‐target effects or rates of reinvasion, particularly over multi‐year time frames. The aims were to evaluate the effectiveness of aerial application of glyphosate for control of dense stands of the invasive grey willow Salix cinerea, and determine the vegetation trajectory over the subsequent 2 yr.LocationWhangamarino Wetland, Waikato, New Zealand.MethodsA before–after control–impact (BACI) experiment was conducted in a Ramsar‐listed wetland in New Zealand. Effects on S. cinerea cover, canopy light interception and non‐target damage were monitored over a 7.1 ha experimental area prior to, and for 2 yr following, aerial application of glyphosate. Vegetation classification, ordination and species richness analyses were undertaken to describe community‐level effects.ResultsAerial application of glyphosate to an established willow canopy was effective in reducing cover to <5% on average for up to 2 yr post‐spray when assessed using 100 m2 vegetation survey plots. Smaller 1 m2 plots were more sensitive for detecting willow reinvasion, which was noted from 1 yr post‐spray. Collateral damage to non‐target sub‐canopy species was generally minimal, except for the native tree fern Dicksonia squarrosa, which showed marked reductions in cover and no recovery over the study period. Species richness was higher in sprayed plots post‐spray and a shift towards a native Carex‐dominated sedgeland community was detected.ConclusionsAerial application of glyphosate to a dense canopy of mature willow was effective in reducing the cover and dominance of this invasive wetland tree species. Minimal collateral damage occurred, facilitating recovery and expansion of a native sedgeland community. The risk of secondary invasion did not eventuate, although exotic species richness spiked in the year following spraying. Sedgelands are susceptible to willow reinvasion via seed, so longer‐term trajectories will diverge depending on management intensity. Using currently available tools, the management options are either repeated cycles of herbicide application to redirect the trajectory from reinvasion to short‐statured sedgelands, or intensive initial management to establish an alternative, more resilient trajectory to native wetland forest.

Mapping Grey Willow (Salix cinerea) stand architecture using airborne laser scanning: implications for large‐scale tree weed control

SummaryWe investigated the potential of airborne laser scanning (ALS) for mapping the stand architecture of Grey Willow (Salix cinerea), an invasive wetland weed in New Zealand. In particular, we focused on two metrics, tree height and canopy density, both of which influence the efficacy and nontarget impacts of herbicides aerially broadcast by helicopter to control tree weeds. We compared ground‐based measures of Grey Willow height and canopy density with ALS‐derived data, and the relationship between canopy density as estimated by each method and aerial herbicide deposition at three wetland sites in New Zealand. Analysis revealed strong linear relationships between ground‐based and ALS metrics, indicating that ALS data could be used to generate accurate, high‐resolution digital maps of Grey Willow height and canopy density. These maps coupled with computer‐guided variable flow rate technologies, which enable optimal placement of herbicide, could maximise Grey Willow mortality while reducing the mortality of nontarget indigenous plants. We recommend the application of ALS‐derived maps and computer‐guided variable flow rate technology is investigated for more targeted large‐scale tree weed control.

Aerial glyphosate application reduces grey willow (Salix cinerea) canopy cover, increases light availability, and stimulates kahikatea (Dacrycarpus dacrydioides) growth

Aerial glyphosate application reduces grey willow (Salix cinerea) canopy cover, increases light availability, and stimulates kahikatea (Dacrycarpus dacrydioides) growth

Enhanced leaf nitrogen status stabilizes omnivore population density

Plant traits can mediate the strength of interactions between omnivorous predators and their prey through density effects and changes in the omnivores’ trophic behavior. In this study, we explored the established assumption that enhanced nutrient status in host plants strengthens the buffering effect of plant feeding for omnivorous predators, i.e., prevents rapid negative population growth during prey density decline and thereby increases and stabilizes omnivore population density. We analyzed 13 years of field data on population densities of a heteropteran omnivore on Salix cinerea stands, arranged along a measured leaf nitrogen gradient and found a 195 % increase in omnivore population density and a 63 % decrease in population variability with an increase in leaf nitrogen status from 26 to 40 mgN × g−1. We recreated the leaf nitrogen gradient in a greenhouse experiment and found, as expected, that increasing leaf nitrogen status enhanced omnivore performance but reduced per capita prey consumption. Feeding on high nitrogen status host plants can potentially decouple omnivore–prey population dynamics and allow omnivores to persist and function effectively at low prey densities to provide “background level” control of insect herbivores. This long-term effect is expected to outweigh the short-term effect on per capita prey consumption—resulting in a net increase in population predation rates with increasing leaf nitrogen status. Conservation biological control of insect pests that makes use of omnivore background control could, as a result, be manipulated via management of crop nitrogen status.

Responses of invertebrates to herbicide in Salix cinerea invaded wetlands: Restoration implications

SummaryThe use of herbicides to control weeds, particularly large invasions, has now become an essential management tool in many ecological restoration projects. The herbicide glyphosate is routinely used to control the invasive weed, Grey Willow (Salix cinerea), within New Zealand wetlands. However, little is known about the effects of glyphosate on invertebrates. We determine the short‐term effects of glyphosate on the abundance and composition of the nontarget canopy invertebrate community in wetlands invaded by Grey Willow in New Zealand. Initially, the application of glyphosate and a surfactant showed no detectable effect on the canopy invertebrates examined in this study. However, 27 days after herbicide application, significant Grey Willow canopy loss caused dramatic decreases in the abundance of invertebrates in the glyphosate‐treated plots compared with the unsprayed plots. Invertebrates appeared to be sensitive to changes in vegetation structure, such as canopy loss. These results agree with previous studies that have shown that the negative impacts of glyphosate on invertebrate communities are related to indirect effects via habitat modification as the herbicide‐treated vegetation dies. From a terrestrial invertebrate perspective, this study suggests that the use of glyphosate herbicide is suitable for the control of invasive weeds within wetland restoration projects as it appears to have negligible impact on the canopy invertebrate assemblage.

Learning from restoration successes in New Zealand

This issue features EMR's first Special Section – in this case on New Zealand restoration. There are many reasons why a focus on New Zealand is relevant to restoration everywhere. Firstly, it is the location of some of the earliest faunal recovery and reintroduction programmes (largely on offshore islands where pest eradication can be feasible) and secondly, that experience has been translated to the mainland areas of the country, whose comparatively small size and relatively low human population has allowed very encouraging levels of success. What is happening in New Zealand is nothing short of inspiring, not least because it shows what is possible in larger countries if the necessary willingness is present. Norton and colleagues’ overview paper, for example, provides a compelling vision, based on successes to date, of a future where the dominant culture is infused with efforts to continuously improve the ecological function of New Zealand's land and water ecosystems, with strong elements of an indigenous world view emerging as part of the dominant paradigm. This potential acceptance of the validity of a restorative approach to land and water management is not a fantasy, but an emerging reality from which other countries can and should learn. The term ‘restoration’ is used by most of the papers in the New Zealand Special Section in a broad sense – that is, inclusive of the entire spectrum of environmental repair including ecological restoration, rehabilitation and mitigation of impacts. Although the terminology is different, this concept is consistent with that underlying the National Standards for the Practice of Ecological Restoration in Australia which emphasizes that the entire spectrum of environmental repair is deserving of attention, not solely sensu stricto ‘Ecological Restoration’. It is ecological restoration in the strict sense, however, that informs what is possible and drives the highest and best standard of work across the board. These highest standards are appropriately applied across Australasia to areas capable of full recovery – but it is the constraints of limited resources and competing land and water uses that usually dictate that in some areas only partial recovery (or rehabilitation) is possible. This ‘culture of possibility’ in New Zealand – where realism meets idealism – is highly nurturing and an appropriate antidote for the grief and despair that often accompanies degradation. The range of articles are described in more detail in the guest editors’ Introduction, but include examples of environmentally and socially transformative restoration and rehabilitation of urban areas (Clarkson & Kirby), forest reserves, and lakes and riparian areas (Elliott & Kemp, Hamilton et al.; McKergow et al.); serious analysis of the phenomenon of strong community involvement in restoration and monitoring by New Zealanders (Sullivan & Molles). Further, the examples of ‘mitigation’ work to protect all areas (not least lakes and streams) from further degradation and provide feasibility for future recovery show that improved sustainability efforts can achieve real outcomes over time. These and similar themes will be featured at the joint conference of the Society for Ecological Restoration Australasia and the New Zealand Ecological Society in November in Hamilton New Zealand (http://era2016.com/) and the Ecological Society of Australia conference in November–December in Fremantle, Western Australia (http://www.ecolsoc.org.au/conferences/registration-now-open). Other articles in this issue include Trevor Booth's guide to using online tools to help select potential sources of diverse seed suited to a changing climate; David Baker-Gabb and colleagues’ test of a simple method for assessing habitat suitability in temperate grasslands; and Corinne Watts' and colleagues' examination of responses of invertebrates to herbicide in Salix cinerea invaded wetlands.

Do moose redistribute nutrients in low-productive fen systems?

The reduction of human use in many grassland systems across Europe has led to bush encroachment and a loss of biodiversity. Low intensity grazing systems by livestock has often been used as a cost-effective management tool to counteract this process. However, not all semi-natural grasslands are suitable for this due to large distance from human settlements or adverse environmental conditions. In this study we address the question whether natural wild large ungulates can be a useful management tool as well. In nutrient-limited systems, large herbivores can affect vegetation dynamics by redistribution of nutrients next to their direct effects on the vegetation. They can preferentially forage plant species and deposit their pellets at other locations leading to nutrient redistribution. We studied whether moose (Alces alces) in the Biebrza National Park (Poland), plays a role in nitrogen dynamics. Microscopic analyses of faeces showed that 57% of the diet consisted of Salix cinerea, which was preferentially foraged upon indicated by a positive Jacobs’ selectivity index. Pellet density was significantly higher in patches of S. cinerea compared to the surrounding vegetation. Based on the chemical composition of moose pellets and the pellet density, we calculated that moose-derived N (faeces and urine) leads to a relevant N-input in willow patches compared to other sources of N in the system. We show that moose do not redistribute nitrogen between different vegetation types but instead speed up the local recycling of nitrogen in patches dominated by willows during the growing season. As a consequence, nutrients become quicker available here than in other parts of the system. We hypothesize that enhanced N-availability in willow patches may off-set the growth reduction caused by moose browsing on willows, which fits to the observed continuous expansion of willows in the study area despite high density of moose. This suggests that moose likely stimulate the growth of willow rather than the often supposed suppression of this woody species. In these systems, more labour-intensive management (f.e. mowing) is required to counteract bush encroachment.

Invertebrate community turnover following control of an invasive weed

Non-native invasive plants are a significant threat to native biodiversity as they change community structure and ecosystem processes and it is becoming imperative that these invasive plants are controlled. We investigated the response of wetland invertebrates to glyphosate chemical control of an introduced tree, grey willow (Salix cinerea), in a before-after-control-impact (BACI) experiment within a New Zealand wetland. Our findings suggest that control of grey willow resulted in significant increases in the abundance of invertebrates within 2 years after herbicide application. Analysis of beetle communities revealed that the abundance and species richness of herbivorous and predacious beetles, the abundance of introduced species, and the species richness of native and introduced species were all significantly higher in the herbicide-treated plots than in the unsprayed plots. The composition of the beetle community separated into two clear groups—plots before spray/no spray and plots 1 and 2 years after herbicide application. We suggest that the beetle compositional changes were driven by complex changes in vegetation associated with the canopy collapse of grey willow trees and the initial influx of introduced plant species, predominantly weedy annuals and perennials, after willow control. Restoration via invasive plant control can promote the reestablishment of invertebrate communities typical of native wetlands, but their long-term sustainability is contingent on prevention of grey willow reinvasion and reestablishment of the native plant habitat.

Detectability of landscape effects on recolonization increases with regional population density.

Variation in population size over time can influence our ability to identify landscape-moderated differences in community assembly. To date, however, most studies at the landscape scale only cover snapshots in time, thereby overlooking the temporal dynamics of populations and communities. In this paper, we present data that illustrate how temporal variation in population density at a regional scale can influence landscape-moderated variation in recolonization and population buildup in disturbed habitat patches. Four common insect species, two omnivores and two herbivores, were monitored over 8 years in 10 willow short-rotation coppice bio-energy stands with a four-year disturbance regime (coppice cycle). The population densities in these regularly disturbed stands were compared to densities in 17 undisturbed natural Salix cinerea (grey willow) stands in the same region. A time series approach was used, utilizing the natural variation between years to statistically model recolonization as a function of landscape composition under two different levels of regional density. Landscape composition, i.e. relative amount of forest vs. open agricultural habitats, largely determined the density of re-colonizing populations following willow coppicing in three of the four species. However, the impact of landscape composition was not detectable in years with low regional density. Our results illustrate that landscape-moderated recolonization can change over time and that considering the temporal dynamics of populations may be crucial when designing and evaluating studies at landscape level.

Translocation of Cd and Mn from Bark to Leaves in Willows on Contaminated Sediments: Delayed Budburst Is Related to High Mn Concentrations

Changes in the hydrology of sediments in tidal marshes or landfills may affect the uptake of metals in the vegetation. Leaf and stem samples of Salix cinerea (grey sallow) were collected during four consecutive growing seasons at six contaminated plots on a polluted dredged sediment landfill and one plot on an uncontaminated reference site. The first three contaminated plots were already emerged in the first half of the first growing season, while the other three were submerged in the first year, but became increasingly dry over the study period. Foliar and stem cutting concentrations for Cd, Zn and Mn increased on the latter three plots over the four years. Willow bark contained high concentrations of Cd, Zn and Mn. In two consecutive greenhouse experiments with willow cuttings from different origins (uncontaminated and contaminated sites) and grown under different soil conditions (uncontaminated and contaminated), we observed an important translocation of Mn from bark to shoots. In a third experiment with willow cuttings collected on soils with a range of heavy metal concentrations and, thus, with a broad range of Cd (4–67 mg/kg dry matter), Zn (247–660 mg/kg dry matter) and Mn (38–524 mg/kg dry matter) concentrations in the bark, high Mn concentrations in the bark were found to affect the budburst of willow cuttings, while no association of delayed budburst with Cd and Zn concentrations in the bark was found. We conclude that wood and, especially, bark are not a sink for metals in living willows. The high Mn concentrations in the bark directly or indirectly caused delayed or restricted budburst of the willow cuttings.

Knowledge of the reproductive ecology of the invasive Salix cinerea, in its invaded range, assists in more targeted management strategies

Management for invasive species is expensive, costing millions of dollars every year and is sometimes unsuccessful. Current control efforts for the highly invasive willow species, Salix cinerea, are extensive, costly, and not always effective because of rapid post-removal reinfestation. An improved knowledge of the reproductive ecology of this species will help design control strategies that minimise future expansion and make current control efforts more effective. To explicitly examine the reproductive ecology of this species in its invaded range in south-eastern Australia, field observations of population structure and sex ratios, pollination experiments and germination trials were undertaken across the Ovens catchment in Victoria. Pollination-exclusion experiments strongly suggest that Salix cinerea in Australia employs two pollen-dispersal mechanisms, with insects being the dominant vector and wind playing a small but significant role (ambophilous). Seed had high initial germination rates, above 95%, but seed is very short-lived with rapid linear decline in germinability until 8 weeks, after which there was no germination at all. An improved understanding of the limited seed bank of this species and the potential it has for long distance pollination has highlighted that preventing reinfestation after control efforts should be focussed on limiting seed production and dispersal. A greater understanding of a species reproductive ecology, particularly of weed species, in their new environment can assist land managers to more effectively target their efforts for long-term eradication strategies.

Plant‐sex‐biased tritrophic interactions on dioecious willow

Plant sex effects on herbivores are well studied, but little is known about these effects on predators and predator–herbivore dynamics. Here we take a holistic approach to study, simultaneously, plant sex effects on herbivore and predator preference and performance, as well as population densities and predation pressure in the field. For dioecious Salix cinerea (grey willow) we found that male plants represented higher host plant quality than females for an omnivorous predator (Anthocoris nemorum, common flower bug), while host plant quality for its herbivorous prey (Phratora vulgatissima, blue willow beetle) was not sex‐biased. The herbivore strongly preferred the host plant sex (female) that was suboptimal for the predator, which in turn followed its prey to female plants, leading to plant‐sex‐biased predation. These results provide new insight into the far‐reaching effects of plant sex on insect communities, and open up novel opportunities for improving biocontrol of the herbivore in Salix short rotation coppice.

The regressive Cirsium rivulare population in an unmown meadow in Białowieża National Park: Influenced by other clonal plants and necromass

This study deals with population dynamics of Cirsium rivulare (brook thistle) present in a meadow that undergoes succession as a result of former disuse. The effect of the following in the succession, currently dominant clonal species and necromass on the performance of the brook thistle population (presence, size of clusters and reproduction) was investigated. The regression stage, the Cirsium rivulare population had attained after mowing, was discontinued. Different kinds of influence from the contiguous species on the brook thistle population could be identified. In the case of Filipendula ulmaria and Carex cespitosa, Cirsium rivulare clusters were found to be present on the edge of the dominant patches. In case of Carex acutiformis patches brook thistle ramets did not form clusters but were present among the sedge ramets. No Cirsium rivulare ramets were found in Phragmites australis and willow (Salix cinerea, S. pentandra and S. aurita) patches. The highest number of generative brook thistle ramets were observed in a Carex acutiformis patch, whereas the highest number of inflorescences on the shoots of the analysed species were identified in the patch dominated by Filipendula ulmaria.Experimental vegetation gaps were created in patches dominated by various species to determine the effect of necromass on the presence of Cirsium rivulare seedlings. A considerable rise in the number of Cirsium rivulare seedlings was noted in Carex acutiformis and Filipendula ulmaria patches following necromass removal in comparison with plots containing necromass. On the other hand, removing the necromass and foliage did not contribute to an increase in the numbers of brook thistle seedlings in the patch dominated by Cirsium rivulare itself.

Beetle community responses to grey willow (Salix cinerea) invasion within three New Zealand wetlands

We investigated the effects of invasion by introduced grey willow (Salix cinerea) on beetle communities within four wetland vegetation types: native vegetation, native vegetation following grey willow removal, native vegetation undergoing grey willow invasion and dense grey willow-dominated vegetation. In total, 1505 beetles from 90 species were collected using modified Malaise traps. Native wetland vegetation had significantly lower beetle species richness than willow-dominated vegetation and was dominated by herbivores, whereas detritivores characterised willow-dominated vegetation. Beetle abundance was highest in the willow-dominated vegetation and mostly comprised detritivores. In contrast, beetle abundance was lowest in native wetland vegetation, but had even proportions of herbivores and detritivores. Native wetland vegetation had a high proportion of native beetles present. As grey willows invaded, introduced beetles became more common. The beetle community composition differed significantly between grey willow-dominated vegetation and native wetland vegetation. These compositional differences were mainly due to the increasing complexity of vegetation structure following grey willow invasion. The beetle communities within restored native wetland vegetation were most similar to those within the native wetland vegetation. From a conservation perspective, these results are encouraging and suggest that, although grey willows dramatically alter the composition of beetle communities present, these communities can be restored to a beetle fauna that is similar to those found within native wetland through the removal of the willows.

Combining Structured Decision Making and Value‐of‐Information Analyses to Identify Robust Management Strategies

Structured decision making and value-of-information analyses can be used to identify robust management strategies even when uncertainty about the response of the system to management is high. We used these methods in a case study of management of the non-native invasive species gray sallow willow (Salix cinerea) in alpine Australia. Establishment of this species is facilitated by wildfire. Managers are charged with developing a management strategy despite extensive uncertainty regarding the frequency of fires, the willow's demography, and the effectiveness of management actions. We worked with managers in Victoria to conduct a formal decision analysis. We used a dynamic model to identify the best management strategy for a range of budgets. We evaluated the robustness of the strategies to uncertainty with value-of-information analyses. Results of the value-of-information analysis indicated that reducing uncertainty would not change which management strategy was identified as the best unless budgets increased substantially. This outcome suggests there would be little value in implementing adaptive management for the problem we analyzed. The value-of-information analyses also highlighted that the main driver of gray sallow willow invasion (i.e., fire frequency) is not necessarily the same factor that is most important for decision making (i.e., willow seed dispersal distance). Value of-information analyses enables managers to better target monitoring and research efforts toward factors critical to making the decision and to assess the need for adaptive management.

Nutrient dynamics in a peatland forest riparian buffer zone and implications for the establishment of planted saplings

Forestry on peatland throughout the world is now focused on minimising destructive effects to the surrounding environment, especially during harvesting. These effects may be mitigated through the use of well-developed riparian buffers zones (RBZs). However, much of the commercial forestry planted in Ireland and the UK in the mid-20th century was planted without adequate RBZs. The creation of new RBZs prior to clearfelling may be a possible mitigation measure in these circumstances. The aim of this paper was to assess the nutrient content and phosphorus (P) adsorption capacity of the soil, and survival of planted saplings in a RBZ, positioned downslope from a standing forest and partly covered with brash mats, five years after its establishment. Dissolved reactive phosphorus (DRP) concentrations were significantly higher under the brash mats in the RBZ when compared to all other areas. The standing forest had the highest concentrations of ammonium nitrogen (NH4-N), while total oxidised nitrogen (TON) was similar for all areas. Water extractable phosphorus and desorption–adsorption testing also confirmed the high concentrations of P under the brash mats, but P did not leach through the peat to the stream. The overall survival rate of the saplings was relatively high, with over half of Quercus robur (oak) (57%), Sorbus aucuparia (rowan) (57%) and Betula pendula (birch) (51%) surviving. Salix cinerea (willow) (22%), Alnus glutinosa (alder) (25%) and Ilex aquifolium (holly) (44%) did not survive as successfully. The RBZ was capable of providing nutrients for the survival of planted saplings, fertilizing the peat with degrading brash material and preventing elevated levels of nutrients entering the adjacent aquatic ecosystem.