Effects Of Past Management Research Articles

‘Latent reserves’: A hidden treasure in National Forest Inventories

Abstract In a Europe shaped by centuries of forest management, the task of today's scientists in characterising, understanding and modelling natural forests is highly challenging. Although numerous forest reserves exist, most remain hardly comparable case studies. Contrarily, National Forest Inventories (NFIs) consist of systematically distributed sample plots with varying time since last intervention and provide representative data. These characteristics make NFIs a unique opportunity to investigate hidden natural forests. Here we propose using NFI plots free of human influence for >40 to >70 years (‘latent reserves’) to conduct large‐scale studies on near‐natural forests. We tested this original concept in Swiss forests. We characterised compositional and structural attributes of ‘latent reserves’ and compared them with those of managed forests to assess whether the former demonstrated more signs of naturalness than the latter. As an example of an application, we analysed the tree‐ and stand‐level factors affecting natural tree mortality in ‘latent reserves’. Up to 15.3% of Swiss NFI plots fulfilled the criteria of ‘latent reserves’, and most of these plots were distributed at mid‐ to high elevations where accessibility and management opportunities are limited. ‘Latent reserves’ showed more signs of naturalness than managed forests—a higher proportion of broadleaves, higher mortality rates, higher stand density and more deadwood. However, their size structure and basal area did not differ from those of managed forests, most likely because of a lower site productivity. Although ‘latent reserves’ were transitioning towards a natural state, more time without management might be required for these forests to become fully detached from the effects of past management, especially at high elevations. Mortality analyses in ‘latent reserves’ showed that species‐specific tree mortality had a U‐shaped response to tree size, was negatively related to tree growth and was higher when competition was stronger. Synthesis. Our findings demonstrate the potential of ‘latent reserves’ to study near‐natural forests at the country level, and point to further opportunities for larger‐scale collaborations. Investigating ‘latent reserves’ represents a first step towards a deeper understanding of such forests using existing long‐term data and shows promise for further research in Europe.

Historical forest management in Romania is imposing strong legacies on contemporary forests and their management

Historical forest management can heavily affect contemporary forest management and conservation. Yet, relatively little is known about century-long changes in forests, and that limits the understanding of how past management and land tenure affect current forestry practice and ecosystem conservation. Our goal here was to examine the relationship between historical forest management (as depicted by historical forest cover, species composition, age structure and harvesting data) and contemporary forest patterns in Romania. Romania represents an ideal case-study to examine the effects of historical forest management, because it experienced multiple shifts in forest management regimes since the 1800s due to Austro-Hungarian, Ottoman, Romanian, Soviet and later EU policy influences, and because it is both a conservation hotspot harboring some of the largest old-growth forest in Europe, and an important source of timber for international markets. We reviewed forestry literature and statistics since the 19th century to reconstruct a time-series of forest cover, composition, disturbance patterns, and ownership patterns and interpreted these data in light of institutional changes. We further assessed changes in forest cover, forest harvest, species composition and age structure between two points in time (1920s and 2010s) at the county level, using a combination of historical forest statistics, remote sensing data and modeled forest composition. We complemented our national data with three case studies for which we had stand-level historical and contemporary forest management data. We found that forest area increased in Romania since 1924 by 5% and that the annual rate of forest harvest between 2000 and 2013 was half of the annual rate between 1912 and 1922, which indicates high potential for forest biodiversity conservation. However, the composition, distribution, and age structure of contemporary forests is also substantially different from historical forests. We found an overall increase in coniferous species and several deciduous species (such as Tilia, Populus, Betula, Alnus sp.), a spatial homogenization of species composition, and more even-aged stands. We also observed a drop from 14% to 9% in the relative abundance of old forests (>100years). Spikes in forest harvest coincided with times of widespread forest privatization, and drastic institutional changes, such as agrarian reforms, or the onset and collapse of the Soviet Regime. Overall, our results suggest that effects of past management, land ownership and institutional changes can persist for centuries, and affect forest ecosystem composition, health and structure, and consequently ecosystem services and habitat availability. Our findings are scientifically important because they provide evidence for legacies of past management and for the effects of forest privatization on harvesting rates. Our findings are also relevant to forest management and conservation practice, because they highlight that environmentally sound management over long time periods is essential for sustainable forestry and old-growth forest protection in Europe and elsewhere.

Forty-year changes in the canopy and the understorey in Wytham Woods

Summary This study investigates changes in the composition of part of Wytham Woods (southern England), between the 1960s and 2007. The study focussed on an area of ~ 4 ha shown on a 1961 aerial photograph, part former open common, part ancient woodland. Changes in the canopy appearance were considered using a recent (1999) aerial photograph. Trees and shrubs were recorded in a 200 × 10 m transect to illustrate current stand structure across the historic management division. In the north-east corner of the area, tree diameters and understorey abundance from 1968 were compared with the current stand structure. Since the 1950s, Fraxinus excelsior has colonized the open areas. Tree growth was estimated from comparison of diameter/girth measurements from 1968 and 2007. F. excelsior diameter increment was greater than that of Acer pseudoplatanus and both showed faster growth than Quercus robur . Some canopy trees died, but no large gaps formed in the closed woodland. The abundance of understorey stems declined. The current stand structure refl ects effects of past management, browsing pressure and climatic stresses over the last four decades. Multiple causes of change are probably commoner than single factors in explaining woodland structure.

Forest structure and C stocks in natural Fagus sylvatica forest in southern Europe: The effects of past management

Managed forests often differ substantially from undisturbed forests in terms of tree structure and diversity. By altering the forest structure, management may affect the C stored in biomass and soil. A survey of 58 natural stands located in the south-westernmost limit of European beech forests was carried out to assess how the C pools are affected by the changes in tree structural diversity resulting from past management. The mean tree density, basal area and the number of large trees found in unmanaged forests were similar to those corresponding to virgin beech forests in Central Europe, whereas large live trees were totally absent from partially cut stands. Analysis of the Evenness index and the Gini coefficient indicated high structural diversity in the three stand types. The results of the Kolmogorov–Smirnov test used to compare the diameter distributions of each group revealed significant differences between stand types in terms of distributions of total tree species and of Fagus sylvatica. The mean C stocks in the whole ecosystem – trees, litter layer and mineral soil – ranged from 220 to 770 Mg ha −1 (average 380 Mg ha −1). Tree biomass (above and belowground), which averaged 293 Mg C ha −1, constituted the main C pool of the system (50–97%). The statistical test (Kolmogorov–Smirnov) revealed differences in the distribution of C pools in tree biomass between unmanaged and partially cut stands. As a consequence of the presence of large trees, in some unmanaged stands the C stock in tree biomass was as high as 500–600 Mg C ha −1. In the partially cut stands, most of the C was mainly accumulated in trees smaller than 20 cm dbh, whereas in unmanaged stands the 30% of tree C pool was found in trees larger than 50 cm dbh. Furthermore, many unmanaged stands showed a larger C pool in the litter layer. The C content of mineral soils ranged from 40 to 260 Mg C ha −1 and it was especially high in umbrisols. In conclusion, the implementation of protective measures in these fragile ecosystems may help to maintain the highly heterogeneous tree structure and enhance the role of both soils and trees as long-term C sinks.

Effects of past management on ice storm damage in hardwood stands in eastern Ontario

The 1998 ice storm caused damage to forests across much of eastern North America. One of the information needs expressed by landowners and the broader forest community in eastern Ontario was an assessment of the effect of past management on degree of damage in hardwood stands. Ice storm damage was assessed in managed and unmanaged permanent sample plots established prior to the ice storm. In addition, 1587 temporary sample plots established after the 1998 ice storm were used to examine the effect of basal area, stand composition, stand location and tree size on degree of ice damage. Permanent sample plot results showed no significant difference in degree of damage between managed and unmanaged hardwood stands that experienced light to moderate damage in eastern Ontario. Chi-square analysis of temporary sample plots showed that the damage varied with location (township). There was some association with stand type (intolerant hardwood, tolerant hardwood, mixed hardwood/conifer and conifer), stand basal area and tree size. Implications for management are discussed. Key words: ice storm damage, past management effects, hardwoods

Change in the balance of ammonium‐N and nitrate‐N content in soil under grazed grass swards over 7 years

The pool of nitrate‐N (NO3–‐N) in the soil is more prone to losses than that of ammonium‐N (NH4+‐N) so any shift towards NO3–‐N dominance in the soil pools, caused by management intensity, could have environmental implications. The change in the balance of soil NH4+‐N and NO3–‐N content with time was studied using grazed grass swards receiving different fertilizer N inputs. In addition, the effect of past management on net nitrification of 400 μg NH4+‐N g–1 was investigated in a soil incubation study. Mineral N was determined at frequent intervals (at least every 2 weeks) throughout the year in the top 5 or 7·5 cm of a sandy clay‐loam soil at the Agricultural Research Institute of Northern Ireland at Hillsborough, County Down, for a 7‐year period (1989–90 to 1995–96). The treatments were a perennial ryegrass–white clover sward receiving no fertilizer N, together with perennial ryegrass swards receiving 100, 200, 300, 400 or 500 kg N ha–1 year–1 as calcium ammonium nitrate. The plots were continuously grazed by beef steers from April to October to maintain a constant sward height of 7 cm. There was little or no change in average soil NO3–‐N and NH4+‐N content from 1989–90 to 1995–96 on the grass–clover sward and plots receiving 100 and 200 kg N ha–1 year–1. However, with the plots receiving 300, 400 and 500 kg N ha–1 year–1 NO3–‐N became progressively more dominant with time. The incubation study confirmed that this was due to an increase in net nitrification rate. There was evidence that rapid microbial assimilation of NO3–‐N occurred during the soil incubations. Past management history can play an important role in determining soil NO3–‐N content and hence potential losses of N to the environment.

Soil Survey Interpretation-Capability Groupings

The capability classification is one of several interpretive soil groupings made for agricultural purposes. The capability groupings provide information at three different levels of generalization; namely, class, subclass, and unit. In the early stages of conservation planning it is important to know for each kind of soil its location, extent, and general suitability for various uses. Soil maps interpreted into the eight capability classes provide this general information. Capability classes are set up so the soils having the greatest alternative uses are in class I and the least in class VIII. When uses are considered collectively, the risks or limitations become progressively greater from class I to class VIII land. Capability subclasses within each of the classes other than class I denote the major kind of conservation problems. Four kinds of problems are recognized in defining subclasses: (1) Runoff and erosion; (2) wetness and drainage; (3) root zone and tillage limitations, such as shallow soil, stones, low moisture capacity, and salinity; and (4) climatic limitations. Within each capability class and subclass the capability units provide specific groupings of similar soils. A capability unit is a group of soils that are nearly alike in potentials for plant growth and responses to management. That is, a reasonably uniform set of alternatives can be presented for the soil, water, and plant management of the soils in a capability unit, assuming that effects of past management are properly considered.