Wild boar (Sus scrofa) has minor effects on soil nutrient and carbon dynamics

Wild boar populations have increased worldwide, but the consequences of their disturbances on boreal forest ecosystems are largely unknown. We investigated how wild boars affect soil processes in a Swedish boreal forest. We estimated effects on ecosystem functioning using phospholipid fatty acid analyses (PLFA) to characterise microbial groups, and by measuring soil respiration, soil carbon (C), nitrogen (N) and phosphorus (P) concentrations, as well as the availability of NO3- and NH4+. We compared samples collected inside wild boar enclosures with adjacent reference areas without wild boar disturbance. We found no difference in soil microbial composition, except for a consistently higher fungi:bacteria ratio in the enclosures. These results are contrary to our hypothesis that rooting raises nitrogen levels, which in turn result in more bacteria. Soil nutrient levels showed inconsistent patterns, suggesting that substrate changes - as opposed to nutrient changes - stimulated fungal growth. Soil respiration was lower in the enclosures, contradicting earlier findings suggesting increased soil CO2 emissions from wild boar rooting. Overall, our study suggests that increased wild boar abundance has a minor impact on soil processes in boreal forests. Future studies should determine if the modest impacts remain across time and boreal forests

Journal Staff

Multi-decadal studies of community and ecosystemdynamics are rare; however, this time frame is most relevant for assessing the impact of anthropogenic influences and climate change on ecosystems. For this reason, we investigated changes in vegetation and microtopography over 52 years in two contrasting mire ecosystems, one ombrotrophic (bog) and one minerotrophic (fen), representing different successional stages and contrasting hydrological settings. In both peatlands, floristic composition was recorded in the same permanent plots (n = 55-56, 0.25 m(2)) in both 1960 and 2012 and microtopography was mapped over a large area (ca. 2500 m(2)) that encompassed these same plots. We quantified and compared the community-level changes and internal spatial dynamics, tested associations between pH/microtopography and community/species change, and examined how the area and location of hummock microforms had changed over time. The bog exhibited little site level change in vegetation, where few species changed significantly in cover and plot frequency. However, detailed analyses revealed some large within-plot changes over time in the bog, illustrating that bogs can be highly dynamic systems at a fine scale. In contrast, the rich fen experienced a clear directional change; specifically, bryophyte abundance decreased by 70% and brown mosses were almost extinct. Although pH had decreased over time at the rich fen, this decrease at the plot-level was not associated with the decline of brown moss abundance. The microtopographic structure did not change substantially at the bog where similar to 70% was covered by lawn/hummocks; however, in the rich fen hummocks expanded (from 10% to 16% cover) and moved or expanded down slope. Our study suggests, that at the site-level, the bog ecosystem was more resistant to environmental changes over time compared to the rich fen, as evidenced by shifts in vegetation and microtopography. The contrasting scales of vegetation dynamics observed within a bog (i.e., within-plot changes vs. site-level) indicate that plant-environment feedbacks contribute to the peatland level stability. While in rich fens, internal feedbacks may be weaker and the ecosystem's vegetation and microtopographic structure are vulnerable to shifting hydrological fluxes

Assessment of agricultural credit : a comparison between different types of industries

The agricultural sector has historically seen stable prices and a relatively constant demand for its products. Companies within the sector have generally had few loans and large sums of money tied in assets. The profitability of the companies has on the other hand been low. Together these circumstances have determined the creditors’ demands on the companies within the sector and have formed the rules and regulations that exist today. These regulations differ from those of companies outside the agricultural sector, especially regulations concerning mortgages on permanent property. The situation, however, is developing towards more market adaptation, larger and fewer agricultural producers as well as more intense price competition. Hence the number of farmers has decreased which has reduced the number of buyers of agricultural property. A smaller number of potential buyers along with bigger market fluctuations have made it difficult for banks to determine future the market values of the assets of agricultural firms. This problem has led to the project's aim, whether or not it is right for banks to apply a different set of rules and regulations specifically for agricultural firms. Subordinate to this aim the project is to determine which valuation method gives the creditor the best possible security. To answer these questions and to reach a conclusion, a study of relevant literature was carried out. Concepts like risk and asymmetric information were studied as well as the farmers’ perception of business and factors that generate value. The literature review led to theoretical conclusions that shaped the questions of the empirical study. The empirical study is limited and concise and the purpose of it is to indicate whether the theoretical conclusions are correct or not. The conclusions are that banks should take into consideration the increasing risk that the development of the farming industry is causing. Creditors should pay more attention to the business managers' achievement capacity since this clearly reflects upon the performance of smaller companies. The banks should increase their insight on the firms’ cash flow as this often reflects companies’ economic status more accurately than for example return on equity. Since the number of farmers decreases, banks should consider being more cautious when it comes to alternative uses of assets when they are used as loan collateral, particularly larger buildings used for animal production

Forest management to increase carbon sequestration in boreal Pinus sylvestris forests

Background and aims Forest management towards increased carbon (C) sequestration has repeatedly been suggested as a "natural climate solution". We evaluated the potential of altered management to increase C sequestration in boreal Pinus sylvestris forest plantations. Methods At 29 forest sites, distributed along a 1300 km latitudinal gradient in Sweden, we studied interactive effects of fertilization and thinning on accumulation of C in standing biomass and the organic horizon over a 40 year period. Results Abstention from thinning increased the total C stock by 50% on average. The increase was significant (14% on average) even when C in the removed timber was included in the total ecosystem C pool. Fertilization of thinned stands increased stocks similarly regardless of including (11%) or excluding (12%) removed biomass, and fertilization combined with abstention from thinning had a synergistic effect on C stocks that generated an increase of 79% (35% when removed timber was included in the C stock). A positive effect of fertilization on C stocks was observed along the entire gradient but was greater in relative terms at high latitudes. Fertilization also reduced soil respiration rates. Conclusion Taken together, our results suggest that changed forest management practices have major potential to increase the C sink of boreal forests. Although promising, these benefits should be evaluated against the undesired effects that such management can have on economic revenue, timber quality, biodiversity and delivery of other ecosystem services

Mitigating wildfire carbon loss in managed northern peatlands through restoration

Northern peatlands can emit large amounts of carbon and harmful smoke pollution during a wildfire. Of particular concern are drained and mined peatlands, where management practices destabilize an array of ecohydrological feedbacks, moss traits and peat properties that moderate water and carbon losses in natural peatlands. Our results demonstrate that drained and mined peatlands in Canada and northern Europe can experience catastrophic deep burns (>200 t C ha(-1) emitted) under current weather conditions. Furthermore, climate change will cause greater water losses in these peatlands and subject even deeper peat layers to wildfire combustion. However, the rewetting of drained peatlands and the restoration of mined peatlands can effectively lower the risk of these deep burns, especially if a new peat moss layer successfully establishes and raises peat moisture content. We argue that restoration efforts are a necessary measure to mitigate the risk of carbon loss in managed peatlands under climate change

Links between boreal forest management, soil fungal communities and below-ground carbon sequestration

1. Forest management has a potential to alter below-ground carbon storage. However, the underlying mechanisms, and the relative importance of carbon input and decomposition in regulation of soil carbon dynamics are poorly understood.2. We examined whether interactive effects of forest fertilization and thinning on carbon stocks in the topsoil of boreal forests were linked to changes in fungal community composition, biomass and enzyme activities, in a long-term fertilization and thinning experiment distributed across 29 Pinus sylvestris forests along a 1,300 km latitudinal transect in Sweden.3. Nitrogen fertilization increased fungal biomass, particularly towards the north and mainly by promoting root-associated Ascomycetes, but the response was moderated by thinning. Fungal biomass correlated positively with carbon stocks in the organic topsoil. However, ectomycorrhizal Cortinarius species were reduced in abundance by fertilization and correlated negatively with carbon stocks.4. Plausibly, increased soil carbon stocks after fertilization are linked to increased input of carbon in the form of root-associated mycelium combined with the loss of ectomycorrhizal decomposers within the genus Cortinarius. These fungal responses to fertilization may mediate a natural climate solution by promoting carbon sequestration in the organic topsoil, but the effect of fertilization may also be undesired from a biodiversity perspective

Disturbance interval modulates the starting point for vegetation succession

Increased frequency and new types of disturbances caused by global change calls for deepened insights into possible alterations of successional pathways. Despite current interest in disturbance interactions there is a striking lack of studies focusing on the implication of decreasing times between disturbances. We surveyed forest-floor vegetation (vascular plants and bryophytes) in a Pinus sylvestris–dominated, even-aged production forest landscape, unique because of the presence of stands under a precisely dated disturbance interval gradient, ranging from 0 to 123 yr between clearcutting and a subsequent megafire. Despite a dominance of early-successional species in all burned stands 5 yr after fire, progression of succession was linked to time since the preceding clearcutting disturbance. This was most clearly seen in increased frequency with time since clearcutting of the dominant, late-successional dwarf shrub Vaccinium myrtillus, with surviving rhizomes as an important mechanism for postfire recovery. Our results demonstrate the role of legacy species as significant drivers of succession. We conclude that the starting point for succession is modulated by disturbance interval, so that shortened intervals risk reducing development towards late-successional stages. We suggest that a decrease in long successional sequences caused by more frequent disturbances may represent a general pattern, relevant also for other forest types and ecosystems

Fire severity as a key determinant of aboveground and belowground biological community recovery in managed even-aged boreal forests

Changes in fire regime of boreal forests in response to climate warming are expected to impact postfire recovery. However, quantitative data on how managed forests sustain and recover from recent fire disturbance are limited.Two years after a large wildfire in managed even-aged boreal forests in Sweden, we investigated how recovery of aboveground and belowground communities, that is, understory vegetation and soil microbial and faunal communities, responded to variation in the severity of soil (i.e., consumption of soil organic matter) and canopy fires (i.e., tree mortality).While fire overall enhanced diversity of understory vegetation through colonization of fire adapted plant species, it reduced the abundance and diversity of soil biota. We observed contrasting effects of tree- and soil-related fire severity on survival and recovery of understory vegetation and soil biological communities. Severe fires that killed overstory Pinus sylvestris promoted a successional stage dominated by the mosses Ceratodon purpureus and Polytrichum juniperinum, but reduced regeneration of tree seedlings and disfavored the ericaceous dwarf-shrub Vaccinium vitis-idaea and the grass Deschampsia flexuosa. Moreover, high tree mortality from fire reduced fungal biomass and changed fungal community composition, in particular that of ectomycorrhizal fungi, and reduced the fungivorous soil Oribatida. In contrast, soil-related fire severity had little impact on vegetation composition, fungal communities, and soil animals. Bacterial communities responded to both tree- and soil-related fire severity.Synthesis: Our results 2 years postfire suggest that a change in fire regime from a historically low-severity ground fire regime, with fires that mainly burns into the soil organic layer, to a stand-replacing fire regime with a high degree of tree mortality, as may be expected with climate change, is likely to impact the short-term recovery of stand structure and above- and belowground species composition of even-aged P. sylvestris boreal forests