Lowland Temperate Forest Research Articles

Conservation at risk: conflict analysis in the Białowieża Forest, a European biodiversity hotspot

The Białowieża Forest is one of the last large remnants of near-natural lowland temperate forest in Europe. For centuries it has had a favourable conservation status by virtue of being a royal game reserve. However, the governance and management changes introduced during the twentieth century have affected the forest's ecological status. For two decades, scientists alongside environmentalists have been debating fiercely with foresters and local residents about effective biodiversity conservation of the Białowieża Forest. Based on a literature review and semi-structured interviews with the main stakeholders in this debate, we analysed the mechanisms underlying the on-going discord, and the assumptions behind the claims of opponents. Important findings were that neither of the opposing groups favoured management options that were optimal for the maintenance of the Białowieża Forest biodiversity values in the long term. Second, persistent tension was fostered through a mutual lack of trust, incompatible appreciation of factual data, local vested interests and by overall economic insecurity of local stakeholders. We discuss the need for restoration-oriented management that would both secure remnants of this irreplaceable ecosystem and restore more disturbed areas of the entire forest massif. There seems to be a need for a shift toward an approach combining bottom-up social processes focused on addressing concrete needs of local stakeholders with strong communication of the clearly identified conservation values of the Białowieża Forest. Finally, incentives for biodiversity conservation must be incorporated into pertinent legislation and funding, as only then would the entire scheme for management and governance stand a chance of success.

Late leaf development in pedunculate oak (Quercus robur): An antiherbivore defence?

Two phenological forms of the pedunculate oak co-occur in the same habitats throughout the species range: the early trees (Quercus robur var. praecox) develop leaves up to 5 weeks before the late ones (Quercus robur var. tardiflora). This study tests the idea that late leaf flushing serves as an antiherbivore defence, i.e. late trees, which develop leaves asynchronously with eclosion of folivorous caterpillars, avoid the costs of defoliation, which could offset the costs of a later onset of the growing season. Effects of folivorous caterpillars foraging on oaks were observed in 1998–2006 in remnants of primeval temperate lowland forest preserved in the Białowieża National Park (eastern Poland). Observations covered trough and outbreak years of the major defoliator, the winter moth [Operophtera brumata L. (Geometridae)]. In seven out of nine seasons, including all peak caterpillar years, the amount of frass produced by folivorous caterpillars on late trees (n=8–18) was significantly (up to 7.1 times) lower than on the early ones (n=12–32). Assessment of the degree of defoliation in 2002–2006 showed that the late oaks were visibly defoliated only during a caterpillar peak (2003), while the early trees were affected in all years and in 2003 almost completely lost their leaves. The results confirm the effect of late budburst on lowering herbivore damage, and give support to the idea that late leaf flushing acts as an antiherbivore defence.

Resource selection by roe deer: Are windthrow gaps attractive feeding places?

Windthrow gaps are often regarded as attractive feeding places for roe deer Capreolus capreolus L. because they are considered to provide more forage than undisturbed forest stands. However, for temperate lowland forests in Central Europe, differences in the quantity of forage in gaps and undisturbed forest stands have not yet been quantified. In two deciduous forests in northern Switzerland, we studied seasonal forage availability in undisturbed forest stands compared to windthrow gaps, with the timber either cleared or uncleared, created by the storm Lothar in 1999. To assess the attractiveness of windthrow gaps for foraging roe deer, we measured seasonal browse consumption by roe deer in these three forest structure types. The amount of available forage mainly varied between seasons and, to a lesser extent, between forest structure types. Windthrow gaps did not generally provide larger quantities of food resources than adjacent undisturbed forest stands. Browse consumption was not directly related to forest structure type, but seems to be dependent on the vertical structure of the understory vegetation (herb/shrub layer). Within forest structure types, browse consumption was constant over seasons, but browsing on individual plant species varied according to season and study site.

Evaluating macrolichens and environmental variables as predictors of the diversity of epiphytic microlichens

Abstract:In contrast to the frequently assessed macrolichens, microlichens are rarely considered in biodiversity assessments despite their high species richness. Microlichens require generally a higher species identification effort than macrolichens. Thus, microlichens are more expensive to assess. Here we evaluate if macrolichen richness can be used as an indicator of total and threatened microlichen richness. Furthermore, we tested if different sets of environmental variables (modelled climatic variables, forest structure, altitude, etc.) improve the regression models based on macrolichens only or even replace the macrolichens as predictors. Multiple linear regressions were used to model species richness of microlichens, and Poisson regressions for threatened microlichens.On 237 forest plots (200 m2) distributed randomly across Switzerland, 77 macrolichens and 219 microlichens occurred. Macrolichen richness was positively related to the richness of microlichens (=0·27) and, in combination with threatened macrolichens as an additional predictor, also to the number of threatened microlichens (=0·14). Environmental variables alone and in different combinations explained between 0·20 and 0·41 () of the total variation of microlichen richness, and between 0·09 and 0·29 () of the total variation of threatened microlichen richness. All models based on environmental variables were considerably improved when macrolichens were included. Furthermore, macrolichen richness turned out to be the most important variable in explaining species richness of all, as well as threatened microlichens. The best models for total microlichen richness reached a of 0·56. Threatened microlichens were more difficult to model with the best model reaching a of 0·29.We conclude that in biodiversity assessments with scarce resources, lichen sampling could be focused on the better known macrolichens, at least in many temperate lowland and mountain forests. In combination with environmental variables, reliable predictions of microlichen richness can be expected. If the focus is on threatened microlichens, however, models were not reliable and specialized taxonomists are necessary to assess these species in the field.

Walkley–Black analysis of forest soil organic carbon: recovery, limitations and uncertainty

AbstractOrganic carbon levels of 542 soil samples from temperate lowland forest were determined by the original and modified Walkley–Black (WB) dichromate methods and total organic carbon (TOC) analysis. The performance and the lower and upper quantification limits of the WB method were assessed. Variable recovery rates were related to laboratory and field conditions and to the sample composition. The percentage carbon recovered by the original WB method was found to be systematically lower than commonly accepted, and the correction factor was estimated at 1.58 instead of 1.30–1.35. However, a good linear relationship with TOC enabled acceptable prediction of soil organic carbon which was most precise when using the original WB method. Texture class and pedogenetic horizon showed significant differences in recovery. Depending on the modifications of the WB method, recoveries varied significantly between laboratories, explaining up to 29% of the total variation of the topsoil carbon assessment of a site. Low recovery from samples was partly attributed to charcoal and resistant elementary carbon particles. No interference was found to be caused by iron or manganese compounds. In order to use WB carbon data of forest soils, laboratory‐ and method‐specific determination of the recovery rate using a total analyser is strongly recommended. The original WB method was unable to predict reliably forest soil carbon contents higher than 8% TOC.

Nest sites, nest depredation, and productivity of avian broods in a primeval temperate forest: do the generalisations hold?

Data on nest success and brood productivity of three ground‐nesting, three canopy‐nesting and four hole‐nesting (non‐excavator) passerines were gathered in a primeval lowland temperate forest (Bialowieza National Park, E Poland). Natural holes were superabundant and the birds had to cope with a heavy pressure of a diverse assemblage of nest predators. We tested whether in such conditions nesting in holes is more productive, and whether nesting on the ground is most risky, as expected from some earlier generalisations. The nesting success varied significantly across the nest types. As predicted, the success of hole‐nesters (51–74%) and their brood productivity were the highest. Contrary to expectations, the ground‐nesters (27–40%) did not breed less successfully than the canopy‐nesters (22–33%). Nest predators, responsible for 64–94% of nest losses in individual species, were the major cause of the differences among nest types. The Bialowieza results confirm the long‐held view that holes tend to be the safest breeding places, but lend no support for the idea that nesting on the ground is more dangerous than in tree crowns.

A new ‘tapir’ from Ellesmere Island, Arctic Canada — Implications for northern high latitude palaeobiogeography and tapir palaeobiology

The oldest and northernmost record of the tapir lineage, Thuliadanta mayri gen. et sp. nov. from Ellesmere Island, Arctic Canada (78°50′N) implies that tapiroid evolution was well underway by early Eocene (Wasatchian) time in northern high latitudes, and raises the possibility of a North American origin for the group. Phylogenetic analyses place the new Arctic tapir as the sister group to the later more advanced Desmatotherium, Colodon, and Irdinolophus. A phylogenetically-derived biogeographic reconstruction posed here suggests the tapir lineage may represent a rare instance of counterflow wherein an exotic North American taxon invaded Asia during the early Eocene. Moreover, Thuliadanta seems a plausible ancestor to Desmatotherium from both continents, suggesting that this branch of the tapir lineage may have originated at high latitudes and subsequently dispersed from there to mid-latitudes. Thuliadanta's occurrence on Ellesmere Island indicates that northern high latitudes should also be evaluated as a potential source area for some of the exotic taxa appearing in mid-latitudes during Eocene time. Using today's tapirs, and specifically the mountain tapir, as analogs, Thuliadanta seems a plausible year-round inhabitant in the mild temperate lowland forests of the Eocene High Arctic.

Invasion by a Perennial Herb Increases Decomposition Rate and Alters Nutrient Availability in Warm Temperate Lowland Forest Remnants

We determined the impact of the invasive herb, Tradescantia fluminensis Vell., on litter decomposition and nutrient availability in a remnant of New Zealand lowland podocarp–broadleaf forest. Using litter bags, we found that litter beneath mats of Tradescantia decomposed at almost twice the rate of litter placed outside the mat. Values of k (decomposition quotient) were 9.44±0.42 yrs for litter placed beneath Tradescantia and 5.42±0.42 yrs for litter placed in native, non-Tradescantia plots. The impact of Tradescantia on decomposition was evident through the smaller forest floor mass in Tradescantia plots (2.65±1.05 t ha−1) compared with non-Tradescantia plots (5.05±1.05 t ha−1), despite similar quantities of annual leaf litterfall into Tradescantia plots (6.85±0.85 t ha−1 yr−1) and non-Tradescantia plots (7.45±1.05 t ha−1 yr−1). Moreover, there was increased plant nitrate available, as captured on resin bags, in Tradescantia plots (25.77 ± 8.32 cmol(−)/kg resin) compared with non-Tradescantia plots (9.55±3.72 cmol(−)/kg resin). Finally, the annual nutrient uptake by Tradescantia represented a large proportion of nutrients in litterfall (41% N, 61% P, 23% Ca, 46% Mg and 83% K), exceeded the nutrient content of the forest floor (except Ca), but was a small proportion of the topsoil nutrient pools. Taken together, our results show that Tradescantia increases litter decomposition and alters nutrient availability, effects that could influence the long-term viability of the majority of podocarp–broadleaf forest remnants affected with Tradescantia in New Zealand. These impacts are likely mostly due to Tradescantia's vegetation structure (i.e., tall, dense mats) and associated microclimate, compared with native ground covers.

Carbon limitation in trees

Summary The ongoing enrichment of the atmosphere with CO2 raises the question of whether growth of forest trees, which represent close to 90% of the global biomass carbon, is still carbon limited at current concentrations of close to 370 p.p.m. As photosynthesis of C3 plants is not CO2‐saturated at such concentrations, enhanced ‘source activity’ of leaves could stimulate ‘sink activity’ (i.e. growth) of plants, provided other resources and developmental controls permit. I explore current levels of non‐structural carbon in trees in natural forests in order to estimate the potential for a carbon‐driven stimulation of growth. The concentration of non‐structural carbohydrates (NSC) in tree tissues is considered a measure of carbon shortage or surplus for growth. A periodic reduction of NSC pools indicates either that carbon demand exceeds con‐current supply, or that both source and sink activity are low. A steady, very high NSC concentration is likely to indicate that photosynthesis fully meets, or even exeeds, that needed for growth (surplus assimilates accumulate). The analysis presented here considers data for mature trees in four climatic zones: the high elevation treeline (in Mexico, the Alps and Northern Sweden), a temperate lowland forest of central Europe, Mediterranean sclerophyllous woodland and a semideciduous tropical forest in Panama. In all four climatic regions, periods of reduced or zero growth show maximum C‐loading of trees (source activity exceeding demand), except for dry midsummer in the Mediterranean. NSC pools are generally high throughout the year, and are not significantly affected by mass fruiting episodes. It is concluded that, irrespective of the reason for its periodic cessation, growth does not seem to be limited by carbon supply. Instead, in all the cases examined, sink activity and its direct control by the environment or developmental constraints, restricts biomass production of trees under current ambient CO2 concentrations. The current carbohydrate charging of mature wild trees from the tropics to the cold limit of tree growth suggests that little (if any) leeway exists for further CO2‐fertilization effects on growth.

Floristic zonation of tree communities on wet tropical mountains revisited

Abstract The altitudes of the ecotones between the main vegetation-zones up mountains of the humid tropics are reviewed, with emphasis on floristics and those areas with which the author is personally familiar. A detailed comparison is made of the zonation on Mt Kinabalu (c. 6°N) and the Himalaya of Bhutan (c. 27°N), and is supported by information from other parts of SE Asia, and to a decreasing extent South America and Africa. The relationship between forest-types based on structure and physiognomy and forest-types based on floristics is complicated. In SE Asia lower montane forests may be dominated by dipterocarps or an ‘oak-laurel’ assemblage. The dominant leaf size in both is notophyll, but the oak-laurel assemblage shifts to the microphyll size-class in China where the transition from tropical lower montane to warm temperate lowland forest begins. The opposite trend is seen where the lower montane flora of Papua New Guinea corresponds to the lowland flora in NE Australia. There are only modest changes between the Equator and the Tropic in the altitudes at which major transitions occur. It is concluded that soil changes, mediated only in part by temperature and associated climatic factors, may play a more direct and diverse role than has previously been indicated. The soil factors emphasized are the increase in organic matter content in lower montane soils as opposed to lowland, accompanied by a change from termite-dominance to earthworm-dominance, and the frequent occurrence of a dense moss layer and mor humus in upper montane soils. The case is made particularly by reference to east Asian mountains, which have been the most studied.

Earthworm biomass and species diversity in windthrow sites of a temperate lowland forest

In temperate forests, disturbance by uprooting of trees is a key process in maintaining species richness and diversity. Nevertheless, very little is known about the changing role and abundance of earthworm communities in different windthrow microsites. The aim of the study was to find (i) whether single-tree uprooting causes significant changes in earthworm biomass and species composition and (ii) which changes in chemical and physical soil properties can be related to it. Twelve single-tree gap sites in an Ulmo-Fraxinetum aceretosum were selected, six sites locally dominated by beech (Fagus sylvatica) and six by poplar (Populus x euramericana). At each site, 7 microsites were sampled for soil chemical and soil physical properties: undisturbed soil beneath closed canopy, undisturbed soil beneath the gap in the canopy layer, the outer side of the pit, the inner side of the pit, the soil fallen from the mound into and away from the pit, and the mound itself. At six sites also earthworms were collected. The impact of microsite on earthworm biomass and species diversity was more important than the impact of tree species. A significant decrease in earthworm biomass and species number was detected from closed canopy over gaps to zones with soil disturbance and finally to windthrow mounds which never contained earthworms. The most pronounced reaction was the negative impact of uprooting on endogeic biomass. Epigeic biomass or species number of any ecological group changed more moderately. Six years after uprooting, microsites with direct soil disturbance were still adverse for earthworms though some – epigeic – species could profit from the absence of competitive species. It is concluded that in temperate lowland forests, the early uprooting phases induce changes in earthworm communities due to changes in soil physical parameters and food availability.

Influence of human impact and bedrock differences on the vegetational history of the Insubrian Southern Alps

Vegetation history for the study region is reconstructed on the basis of pollen, charcoal and AMS14C investigations of lake sediments from Lago del Segrino (calcareous bedrock) and Lago di Muzzano (siliceous bedrock). Late-glacial forests were characterised byBetula andPinus sylvestris. At the beginning of the Holocene they were replaced by temperate continental forest and shrub communities. A special type of temperate lowland forest, withAbies alba as the most important tree, was present in the period 8300 to 4500 B.P. Subsequently,Fagus, Quercus andAlnus glutinosa were the main forest components andA. alba ceased to be of importance.Castanea sativa andJuglans regia were probably introduced after forest clearance by fire during the first century A.D. On soils derived from siliceous bedrock,C. sativa was already dominant at ca. A.D. 200 (A.D. dates are in calendar years). In limestone areas, however,C. sativa failed to achieve a dominant role. After the introduction ofC. sativa, the main trees were initially oak (Quercus spp.) and later the walnut (Juglans regia). Ostrya carpinifolia became the dominant tree around Lago del Segrino only in the last 100–200 years though it had spread into the area at ca. 5000 cal. B.C. This recent expansion ofOstrya is confirmed at other sites and appears to be controlled by human disturbances involving especially clearance. It is argued that these forests should not be regarded as climax communities. It is suggested that under undisturbed succession they would develop into mixed deciduous forests consisting ofFraxinus excelsior, Tilia, Ulmus, Quercus andAcer.

What Happens to Old Nests in Natural Cavities?

It is well known that old nest material accumulates in nest boxes and should be removed to keep the boxes usable. Perrins (1979) and M0ller (1989) proposed that the removal of old material, via reduction of ectoparasites, could improve conditions in the boxes. This in turn could have profound effects on nest-site choice, mating success, and reproductive efficiency of the individuals that use the boxes. Natural cavities are not cleaned by humans. Thus, by implication, conditions in them should deteriorate owing to the accumulation of old nest material. Indeed, Perrins (1979) stated that . . the nest material would slowly decompose within the chamber and presumably over a series of years the site might become filled with old nests. I have tried to find support for this statement in the literature, but so far I have failed to find any information on this issue. Therefore, it seems that the information presented below, which indicates that old nest material disappears rapidly from natural cavities, constitutes the first data on this subject. Study Area and Methods.-Data were gathered from 1992 to 1998 in the Bialowieza National Park in eastern Poland, within which the last surviving fragments of European primeval lowland temperate forest are preserved. The tree stands of the park have never been cut, and the entire area has been strictly protected as a reserve since 1921. Hence, one can still observe cavities and cavity nesters in conditions free of direct anthropogenic disturbance. The forest consists of several types of old-growth stands (see Tomialojd and Wesolowski 1990, Tomialojc 1991, Wesolowski and Tomialojd 1995), but most of the data were gathered in two types of chiefly deciduous stands. One was a stand of riparian trees composed mostly of alder (Alnus glutinosa), ash (Fraxinus excelsior), and Norway spruce (Picea excelsa); the other was a stand of upland deciduous forest composed of more than 12 species of trees, mainly hornbeam (Carpinus betulus), small-leafed linden (Tilia cordata), con-

Tornado damage and initial recovery in three adjacent, lowland temperate forests in Missouri

Abstract. We surveyed tornado damage 14 months after disturbance in three adjacent forest sites in southeastern Missouri, USA: upland, an occasionally‐flooded lowland and a frequently flooded swamp. We analysed three 0.09‐ha plots in the swamp, and three 0.04‐ha plots in the other sites and recorded the herbaceous‐layer in five 1‐m2 quadrats per plot.Overall, 30 % of the individuals and 64 % of the basal area of these sites was blown down. However, mortality was less than structural damage: 20 % of the trees were dead 14 months post‐disturbance, an intermediate level of mortality relative to other wind disturbances. Damage varied widely among species, sites and tree sizes, but large trees of all species were most likely to be damaged and least likely to resprout.While damage was greatest in the wettest site, we attribute the increase to larger tree sizes and lower density there, rather than to inherent rooting instability. This study suggests that different forest composition and structure may be sufficient to cause differential damage, without topographic effects. Herbaceous‐layer response was more rapid than in a previously reported tornado windthrow in Pennsylvania, and was dominated by fast‐growing, shade‐intolerant forbs.

Earthworms as bio-indicators of forest site quality

The effectiveness of earthworm species as bio-indicators of forest site quality was tested by a dataset of 180 plots in temperate lowland forest (Flanders, Belgium). In these plots, earthworm samples were taken together with vegetation surveys and additional site quality parameters. Vegetation surveys were used to calculate mean humidity, acidity and nitrification indices and to display sites in a humus quality-soil humidity-ecogram. In this ecogram, the earthworm biomass per species, per ecological category and in total was related with timber growth indices for ash ( Fraxinus excelsior) and beech ( Fagus sylvatica). The observed parallels and discrepancies are discussed.

Winter distribution and abundance of mustelids and beavers in the river valleys of Białowieża Primeval Forest

Lutra lutra, Mustela vison, M. putorius, M. erminea, M. nivalis, and the settlements of Castor fiber were surveyed along 170 km of rivers in Bialowieza Primeval Forest (Poland and Belarus), the best preserved temperate lowland forest in Europe. The censused rivers varied from very small (1-5 m wide, <1 m deep) to medium-sized (11-15 m wide, up to 3 m deep). Mustelids were counted by tracks left in snow.