人工油松林中跳虫群落恢复状况

Large areas of forest plantations have been developed in China.It is important to evaluate the soil fauna in plantations and the conditions needed for their recovery in view of the large areas of plantations in China.Three Pinus tabulaeformis forests,a 26-year-old plantation (P26) and a 45-year-old plantation (P45),exposed to clear-cutting before plantation,and an 80-260-year-old natural forest (N260),were chosen to study the effects of different forest ages/types on Collembola community in the litter and soil layers during 2008 and 2009.Soil conditions in P26 and P45 were significantly deteriorated when compared to N260.A higher value of soil bulk density and lower values of soil organic matter,soil N,litter depth,soil pH,and soil water content were observed in P26 and P45.Totally,the same genera of Collembola tended to occur in the forests of all ages studied;however,the Collembola community structure was significantly impacted by the differences in forest age.Both in the litter and soil layers,the density and generic richness of the Collembola were the highest in N260 and the lowest in P26.Some collembolan groups were sensitive to soil conditions in particular forest ages.N260 was associated with relatively high abundance of Plutomurus collembolans and P45 with relatively high abundance of Pseudofolsomia collembolans.The canonical correspondence analysis showed that the community structure of Collembola was mainly affected by forest age in both litter and soil layer.The ordination analysis of non-metric multidimensional scaling also found that the Collembola community did not recover to the level of natural forests in 26-year regeneration after clear-cutting.Even in 45-year regeneration after clear-cutting,the Collembola community only showed a slight recovery to the level of natural forests.Our results clearly showed that both Collembola community and soil conditions did not recover in 26-and 45-year regeneration after clear-cutting in P.tabulaeformis plantations;however,they might have the potential to recover in the future because the same genera of Collembola were distributed in the plantations and natural forests.     

Downed logs improve soil properties in old-growth temperate forests of northern Iran

Dead trees, particularly downed logs, play an important role in the dynamics of forest ecosystem. Contribution of decaying wood to C and nutrient pools of forest soils depends on the tree species and degree of wood decay. However, the extent to which the downed logs affect the soil properties of temperate forests has rarely been evaluated. In this study, a mixed beech forest was selected in Liresar region of Mazandaran Province, northern Iran, to investigate if and how the presence of downed logs affected soil quality and function by comparing soils underneath degraded logs and nearby soils of the two dominant tree species(beech and hornbeam). We then explored how these effects occurred as downed logs decomposed by comparing the woods of both tree species at four degrees of decomposition. Degree of decay of downed logs was classified into four classes(DC1–DC4). Eight dead trees of each tree species were selected at the center of each sample plot. Three composite soil samples underneath each decaying log and 100 cm away from a decaying log were collected at two soil depths(0–15 and 15–30 cm) to analyze soil main physicochemical properties and microbial activity. The results revealed that downed logs affected soil physical(5% wetter than control soils), chemical(2% lower pH, 100% increase in organic C and total N in the case of hornbeam, and 2% increase in P), and biological characteristics(soil microbial respiration enhanced by 10%, and microbial biomass C 620 and 351.5 mg kg~(-1) and microbial biomass N 66.47 and 32.18 mg kg~(-1), respectively, in the cases of beech and hornbeam), thus resulting in significantly different soil microsites from those without downed logs. Presence of downed logs increased soil microbial activity and soil fertility as wood decayed. Thus, the presence of downed logs is an important factor influencing forest soils and should be taken into consideration in forest management practices.     

生态毒理学工具在评价石油化工厂区土地耕作适宜性中的运用

The demand for simple and rapid bioassays in ecotoxicological evaluations is of paramount importance in order to speed up environmental monitoring programs. In this study we performed bioassays with lettuce seeds and two species of terrestrial isopods （Armadillidium vulgare and Porcellio dilatatus） for the ecotoxicological assessment of a landfarming soil from a petrochemical complex area. The solubilized content of test soil demonstrated a concentration-response type toxic effect on seed germination rate, and a delay on germination, but showed toxic effect on seedlings wet weight only at the highest concentration. Toxic effects were also observed in mortality rate and avoidance behavior of the two woodlice species. These results demonstrated the sensitiveness of the organisms studied, and highlighted the possibility to use these bioassays in environmental monitoring programs in areas contaminated with fossil fuels.     

川西3种亚高山针叶林的养分和凋落物格局分析

Investigations were conducted to quantify litterfall, and litter and nutrient accumulation in forest floor, and to acquire information on litter decomposition and nitrogen and phosphorus release patterns in three different subalpine coniferous forests, a plantation （P1）, a secondary forest （SF）, and a primitive forest （PF）, in western Sichuan, China. The litter trap method was used to evaluate litterfall with the litterbag method being utilized for litter decomposition. Seasonal patterns of litterfall were similar in the three forests, with two peaks occurring in September-November and March-May. The plantation revealed an annual litterfall of 4.38 x 103 kg ha-1, which was similar to those of SF and PF, but P1 had a lower mass loss rate and a higher C/N ratio. The C/N ratio may be a sound predictor for the decomposition differences. N concentrations of leaf litter in both the secondary forest and primitive forest increased first and then decreased, and the percentages of their final/initial values were 108.9% and 99.9%, respectively. P concentration in the three forests increased by the end of the study. The results of litterfall and decomposition indicated that in the plantation the potential to provide nutrients for soil organic matter was similar to those of SF and PF; however, its slower decomposition rate could result in a somewhat transient accumulation of litter in the forest floor.     

南亚热带森林演替过程土壤水分、有机质和交换性阳离子的变化格局

Information on the distribution patterns of soil water content （SWC）, soil organic matter （SOM）, and soil exchangeable cations （SEC） is important for managing forest ecosystems in a sustainable manner. This study investigated how SWC, SOM, and SEC were influenced in forests along a successional gradient, including a regional climax （monsoon evergreen broad-leaved forest, or MEBF）, a transitional forest （coniferous and broad-leaved mixed forest, or MF）, and a pioneer forest （coniferous Masson pine （Pinus rnassoniana） forest, or MPF） of the Dinghushan Biosphere Reserve in the subtropical region of southern China. SWC, SOM, and SEC excluding Ca^2＋ were found to increase in the soil during forest succession, being highest in the top soil layer （0 to 15 cm depth） except for Na^＋. The differences between soil layers were largest in MF. This finding also suggested that the nutrients were enriched in the topsoil when they became increasingly scarce in the soil. There were no significant differences （P = 0.05） among SWC, SOM, and SEC. A linear, positive correlation was found between SWC and SOM. The correlation between SOM and cation exchange capacity （CEC） was statistically significant, which agreed with the theory that the most important factor determining SEC is SOM. The ratio of K^＋ to Na^＋ in the topsoil was about a half of that in the plants of each forest. MF had the lowest exchangeable Ca^2＋ concentration among the three forests and Ca^2＋：K^＋ in MPF was two times higher than that in MF. Understanding the changes of SWC, SOM, and CEC during forest succession would be of great help in protecting all three forests in southern China.     

Soil biological changes for a natural forest and two plantations in subtropical China

Conversion of natural forests into pure plantation forests is a common management practice in subtropical China. To evaluate the effects of forest conversion on soil fertility, microbe numbers and enzyme activities in topsoils (0-10 cm) were quantified in two 33-year-old monoculture plantations of Castanopsis kawakamii Hayata (CK) and Cunninghamia lanceolata Lamb. (Chinese fir) (CF), and compared to a neighboring relict natural C. kawakamii forest (NF), in Sanming, Fujian. Five soil samples were collected once each in January, April, July, September and November in 2000 in each forest for laboratory analysis. Over the sampling year, there were significant differences for bacteria, fungi and actinomycetes between forests and between seasons (P < 0.05). The largest bacteria and fungi populations were in NF, while CF contained the greatest number of actinomycetes. There were also significant differences (P < 0.05) with microbial respiration for forests and seasons. Additionally, compared with NF, urease and acid phosphatase were significantly lower (P < 0.05) in CK and CF. Also, the correlations of soil hydrolysable N and available P to soil microbial and enzymatic activities were highly significant (P < 0.01). Thus, to alter the traditional Chinese fir monoculture so as to mimic the natural forest conditions, managing mixed stands of Chinese fir and broadleaf trees or conducting crop rotation of conifers and broadleaf trees as well as minimizing forest disturbances like clear-cutting, slash burning and soil preparing, could be utilized.     

华南受干扰林和成熟林氮素流失对模拟氮沉降的响应

Current nitrogen (N) leaching losses and their responses to monthly N additions were investigated under a disturbed pine (Pinus massoniana) forest and a mature monsoon broadleaf forest in southern China. N leaching losses from both disturbed and mature forests were quite high (14.6 and 29.2 kg N ha^-1 year^-1, respectively), accounting for 57% and 80% of their corresponding atmospheric N inputs. N leaching losses were substantially increased following the first 1.5 years of N applications in both forests. The average increases induced by the addition of 50 and 100 kg N ha^-1 year^-1 were 36.5 and 24.9 kg N ha^-1 year^-1, respectively, in the mature forest, accounting for 73.0% and 24.9% of the annual amount of N added, and 14.2 and 16.8 kg N ha^-1 year^-1 in the disturbed forest, accounting for 28.4% and 16.8% of the added N. Great N leaching and a fast N leaching response to N additions in the mature forest might result from long-term N accumulation and high ambient N deposition load (greater than 30 kg N ha^-1 year^-1 over the past 15 years), whereas in the disturbed forest, it might result from the human disturbance and high ambient N deposition load. These results suggest that both disturbed and mature forests in the study region may be sensitive to increasing N deposition.     

川西亚高山三个森林群落的凋落物动态

Litter production, components and dynamics were investigated and forest floor litter was quantified throughout a whole year in three subalpine forests, dominated by tree species of spruce （SF）, fir （FF） and birch （BF）, in Western Sichuan, China, in order to understand the key factors that influenced litter production and dynamics. Litterfall in the three forests consisted mainly of leaves, woody litter, reproductive organs and moss. Contribution of leaf litter to the total litterfall was significantly （P 〈 0.05） greater than that of woody litter, reproductive organs or moss. Regardless of the stands, litterfall exhibited a marked monthly variation with the maximum litterfall peaks occurring in October, with smaller peaks occurring in February for SF and FF, and May for BF. The analysis indicated that tree species, stand density, leaf area index （LAI）, stand basal area and stand age were the key factors determining litter production. Meanwhile tree species and phenology controlled the litter dynamics, with wind and snow modifying the litter components and dynamics.     

Responses of Soil Acid Phosphomonoesterase Activity to Simulated Nitrogen Deposition in Three Forests of Subtropical China

Soil acid phosphomonoesterase activity(APA)plays a vital role in controlling phosphorus(P)cycling and reflecting the current degree of P limitation.Responses of soil APA to elevating nitrogen(N)deposition are important because of their potential applications in addressing the relationship between N and P in forest ecosystems.A study of responses of soil APA to simulated N deposition was conducted in three succession forests of subtropical China.The three forests include a Masson pine(Pinus massoniana)forest (MPF)-pioneer community,a coniferous and broad-leaved mixed forest(MF)-transition community and a monsoon evergreen broad-leaved forest(MEBF)-climax community.Four N treatments were designed for MEBF:control(without N added),low-N(50 kg N ha^-1 year^-1),and medium-N(100 kg N ha^-1 year^-1)and high-N(150 kg N ha^-1 year^-1),and only three N treatments(i.e.,control, low-N,medium-N)were established for MPF and MF.Results showed that soil APA was highest in MEBF,followed by MPF and MF.Soil APAs in both MPF and MF were not influenced by low-N treatments but depressed in medium-N treatments.However,soil APA in MEBF exhibited negative responses to high N additions,indicating that the environment of enhanced N depositions would reduce P supply for the mature forest ecosystem.Soil APA and its responses to N additions in subtropical forests were closely related to the succession stages in the forests.     

南亚热带森林干季期间土壤变湿后一氧化氮排放

Information about soil nitric oxide (NO) emissions from subtropical forests is quite limited, and even less is known about the pulse emission of NO when wetting soils after a long period of dryness. In this study, we measured NO fluxes following wetting of dry soil in a broadleaf forest and a pine forest in subtropical China. Large pulses of NO fluxes were observed after soil wetting in both forests. NO fluxes increased significantly within 0.5 h following wetting in both forests and reached peak 1 h and 4 h after soil wetting in the pine forest and the broadleaf forest, respectively. In the broadleaf forest, averaged peak flux of NO pulses was 157 ng N m–2 s–1, which was 8 times the flux value before wetting, and in the pine forest, the averaged peak flux was 135 ng N m–2 s–1, which was 15.5 times the flux value before wetting. The total pulses-induced NO emissions during the dry season were roughly estimated to be 29.4 mg N m–2 in the broadleaf forest and 22.2 mg N m–2 in the pine forest or made up a proportion of 4.6% of the annual NO emission in the broadleaf forest and 5.3% in the pine forest.     

Seasonal dynamics of the physicochemical and biological properties of soils in naturally regenerating,unmanaged and clear-cut beech stands in northern Spain

The physicochemical and biological properties of soils within an unmanaged beech stand and two stands clear-cut in 2001 or 1996 were studied and compared across the year 2008. The clear-cut stands were left to naturally regenerate and exhibited very different levels of tree density. Soil from the stand clear-cut in 2001 had the lowest contents of organic matter and nitrogen, showed high resistance to penetration and the pH varied throughout the seasons. Basal respiration achieved minimum values in summer in both the unmanaged stand and the stand clear-cut in 1996. However, basal respiration slightly fluctuated from spring to autumn in the stand clear-cut in 2001. The seasonal dynamics of protease and phosphatase activities were similar within the three stands: the maximum protease activity was detected in spring and the highest phophatase activity in winter. β-Glucosidase activity in autumn and dehydrogenase in winter were greater in the unmanaged than in the clear-cut stands. Moreover, dehydrogenase activity was extremely low in the stand clear-cut in 1996. Microclimatic parameters within the stands were significantly correlated with several biological properties of soils, with microclimate being strongly determined by the density of trees. Results also suggested that ectomycorrhizal fungi would be key components of the soil microflora in the beech forests.     

Effects of forest management on carabid beetles in Belgium: implications for biodiversity conservation

We sampled the carabid beetles in 22 forests managed by six different silvicultural systems, defined by treatment and tree species composition: even-aged conifer, even-aged beech, even-aged oak, uneven-aged conifer, uneven-aged beech and group mixed (beech + conifer). In each of these forests, we placed pitfall traps in young, medium-aged and mature stands (3 stages). We evaluated the effect of treatment, tree species composition, silvicultural system, stage and habitat type (silvicultural system + stage) on indicators of community conservation value and ecological structure. The species composition and the ecological structure of carabid beetles of the managed stands were then compared to that of nine unmanaged stands (without tree exploitation). In the managed forests, species richness was highest in large young stands (3-10 years old) and in forests managed by even-aged systems (with large clear-cuts), mainly due to eurytopic and opportunist carabid species with high dispersal abilities. Oak and beech, uneven-aged, and mature stands were mainly inhabited by typical forest species, and even-aged conifer stands mainly by ubiquitous species. Several typical forest species recorded in unmanaged stands were lacking from the managed forests. Large scale clear-cutting allows open-habitat species to enter the forest, which increases the species richness at a landscape level but can disfavour typical forest species by competition. Long rotations should be implemented and more areas left unmanaged in Belgium, in order to help typical forest species to re-colonise managed forests.     

Observation and Confirmation of Foliar Ozone Symptoms of Native Plant Species of Switzerland and Southern Spain

Tropospheric ozone is considered as the major pollutant of concern to the health and productivity of forests in the eastern United States and has more recently become of increasing concern within the forests of southern Europe. Recent observations have clearly demonstrated foliar injury symptoms to be occurring on many tree and native plant species within remote forested areas. Several plant genera (and a few species within genera) found in both the forests of Switzerland and the southern coastal region of Spain exhibit field symptoms typical of ambient ozone exposures. Ozone exposures for many species have been conducted under controlled CSTR conditions and within open-top chambers within the study areas. Results have confirmed that the O₃-like foliar symptoms as observed under natural forest and open grown conditions for many native tree, shrub, and herbaceous species in Spain and Switzerland are caused by exposures to ambient O₃.     

Conservation value of tropical secondary forest: A herpetofaunal perspective

In some areas of the tropics forests are recovering on abandoned cattle pastures. These secondary forests may be important habitats for conserving biodiversity, but we know little about their species composition over the long term. We studied herpetofaunal community changes in a 40 years chronosequence of forest succession on abandoned pastures in Puerto Rico. Twelve submontane sites (100-250 masl) represented four forest recovery stages: pasture, young (1-5 years after abandonment), intermediate (10-20 years), and advanced (40 years). Among these stages we analyzed the relationship of forest structure, microclimate, and herpetofaunal community structure. During succession total forest height increased, new strata of vegetation appeared in the understory, and the forest gained heterogeneity and complexity. Microclimate changed with changes in the physiognomy and structure of the vegetation. Microclimatic shifts were more dramatic in forest <20 years since abandonment. During 1 year we observed 7991 individuals of thirteen reptilian species (60% of observations) and six anuran species. Herpetofaunal richness was similar among stages, but the total abundance increased through succession. Relative abundance of anurans and reptiles was similar between stages, but species dominance changed with succession. Forest >20 years old resembles mature forest in some structural characteristics important to herpetofauna and can provide habitat for forest herpetofauna in disturbed areas.     

Influence of tree characteristics and forest management on tree microhabitats

Higher densities of tree microhabitats in unmanaged forests may explain biodiversity differences with managed forests. To better understand the determinants of this potential biodiversity indicator, we studied the influence of tree characteristics on a set of tree microhabitats (e.g. cavities, cracks, bark features) on 75 plots in managed and unmanaged French forests. We hypothesized that the number of different microhabitat types per tree and the occurrence of a given microhabitat type on a tree would be higher in unmanaged than in managed forests, and that this difference could be linked to individual tree characteristics: diameter, vitality and species. We show that unmanaged forests contained more trees likely to host microhabitats (i.e. large trees, snags) at the stand level. However, at the tree level, forest management did not influence microhabitats; only tree characteristics did: large trees and snags contained more microhabitats. The number and occurrence of microhabitats also varied with tree species: oaks and beech generally hosted more microhabitats, but occurrence of certain types of microhabitats was higher on fir and spruce. We conclude that, even though microhabitats are not equally distributed between managed and unmanaged forests, two trees with similar characteristics in similar site conditions have the same number and probability of occurrence of microhabitats, whatever the management type. In order to preserve biodiversity, foresters could reproduce unmanaged forest features in managed forests through the conservation of specific tree types (e.g. veteran trees, snags). Tree microhabitats could also be more often targeted in sustainable forest management monitoring.     

Does forest type and vegetation patchiness influence horizontal distribution of soil Collembola in two neighbouring forest sites?

The influence of forest type and heterogeneity of understory vegetation on the horizontal distribution of soil living Collembola was studied in two neighbouring mountain forest sites—a 180-year old beech forest and a 70-year old natural spruce forest. Four homogenous patches with different understory vegetation were chosen within each forest site and sampled 12 times between 1997 and 1998. A total of 56 collembolan species were identified, 51 in the beech forest and 48 in the spruce site. Twenty-three species were rare—they were recorded with low constancy and density. Although both forest sites differed in soil type, humus form and soil chemical parameters, the species composition of their collembolan communities was quite similar (77% shared species). Nevertheless, soil collembolan communities of both forest sites were clearly delimited on both qualitative (presence–absence) and quantitative (in density of individual species) levels as well as in terms of total collembolan density. Mean collembolan density reached 26 650–44 030 ind/m² in the beech patches compared to 44 470–68 050 ind/m² found in the spruce patches. Considerably higher densities of several species in one forest site may indicate more suitable habitat. In spite of similar species composition and minor differences in qualitative parameters among different vegetation patches within one forest site, there was clear variation in density of individual species, particularly between patches with and without herb vegetation. This could reflect different microclimatic conditions, additional litter supply from herbs or indirect interactions of Collembola with their roots.     

ARBUSCULAR MYCORRHIZAL FUNGI IN REVEGETATED MINED DUNES

This study aimed to thoroughly investigate communities of arbuscular mycorrhizal fungi (AMF) in six coastal, mined, reconstituted and revegetated dune areas in Northeast Brazil. AMF spore density and species richness as well as the numbers of infective AMF propagules and glomalin‐related soil protein (GRSP) were analyzed. Four areas had been restored for 16, 12, 8 and 4 years, and after being mined, reconstituted and re‐vegetated, the fifth was mined and reconstituted but not yet re‐vegetated, and the sixth had a native and undisturbed coastal forest vegetation. The soil samples were sampled in the dry and wet seasons of 2005. The number of infective propagules was significantly higher in the dry than in wet season, except in the un‐vegetated dune area, which had less than 0·2 propagules cm⁻³ soil. AMF spore density and especially GRSP contents changed little between the seasons. GRSP contents were positively correlated to Al and Fe soil levels and were highest in the restinga forest. In total, 29 AMF species were identified, and glomoid and gigasporoid species predominated in all areas. AMF species richness and viable propagules of AMF were lowest in the un‐vegetated dune area. Remarkably, higher species richness (28) was found in the re‐vegetated areas, compared with the forest area that had only 10 species. The numbers of infective propagules tended to be also lower in the forest than in the re‐vegetated sites. In conclusion, re‐vegetation appears to favour the AMF communities in terms of infective propagule numbers and AMF species richness. Copyright © 2011 John Wiley & Sons, Ltd.     

Urbanization and riparian forest woody communities: Diversity, composition, and structure within a metropolitan landscape

Understanding how urban land-use structure contributes to the abundance and diversity of riparian woody species can inform management and conservation efforts. Yet, previous studies have focused on broad-scale (e.g., urban to exurban) land-use types and have not examined more local-scale changes in land use (e.g., the variation within “urban”), which could be important in urban areas. In this paper we examine how local-scale characteristics or fine-scale urban heterogeneity affect(s) the diversity, composition, and structure of temperate woody riparian vegetation communities in the highly urbanized area of Cincinnati, Ohio, USA. We use an information-theoretic approach to compare vegetation models and canonical correspondence analyses to compare species responses to urban variables. We found that urban riparian areas can harbor a high diversity of native canopy and shrub species (38 and 41, respectively); however, native and exotic woody plant species responded differently to urbanization. Exotic canopy species increased with the level of urbanization while native canopy and understory species declined. Understory species diversity displayed a greater response to urbanization than did canopy diversity, suggesting temporal lags in canopy response to disturbances associated with present and recent land-use changes. Certain native and exotic woody species represent ecological indicators of different levels of urbanization. Native species characteristic of pre-European settlement conditions were restricted to the wide riparian forests with little urban encroachment. Several native early-successional species appear tolerant to urbanization. Two exotic species, the tree Ailanthus altissima and the shrub Lonicera maackii, were the most abundant and ubiquitous woody species and appear to exploit urban disturbances. These exotic species invasions have the potential to modify forest composition and ecological function of urban riparian systems. In addition, altered hydrology may be a contributing factor as canopy and understory stem density of high-moisture-requiring species decreased with an increase in impervious surface and grass cover and with proximity to roads and railroads. In the face of urbanization, maintaining wide riparian forests and limiting building, road and railroad development within these areas may help reduce the invasion of exotic species and benefit hydrological function in temperate riparian areas.     

The effects of invasive North American beavers on riparian plant communities in Cape Horn, Chile: Do exotic beavers engineer differently in sub-Antarctic ecosystems?

North American beavers (Castor canadensis) were introduced into southern South America in 1946. Since that time, their populations have greatly expanded. In their native range, beavers shape riparian ecosystems by selectively feeding on particular plant species, increasing herbaceous richness and creating a distinct plant community. To test their effects as exotic engineers on sub-Antarctic vegetation, we quantified beaver impacts on tree canopy cover and seedling abundance and composition, as well as their impacts on herbaceous species richness, abundance and composition on Navarino Island, Cape Horn County, Chile (55°S). Beavers significantly reduced forest canopy up to 30 m away from streams, essentially eliminating riparian forests. The tree seedling bank was greatly reduced and seedling species composition was changed by suppressing Nothofagus betuloides and Nothofagus pumilio, but allowing Nothofagus antarctica. Herbaceous richness and abundance almost doubled in meadows. However, unlike beaver effects on North American herbaceous plant communities, much of this richness was due to invasion by exotic plants, and beaver modifications of the meadow vegetation assemblage did not result in a significantly different community, compared to forests. Overall, 42% of plant species were shared between both habitat types. Our results indicate that, as predicted from North American studies, beaver-engineering increased local herbaceous richness. Unlike in their native range, though, they did not create a unique plant community in sub-Antarctic landscapes. Plus, the elimination of Nothofagus forests and their seedling bank and the creation of invasion pathways for exotic plants together threaten one of the world’s most pristine temperate forest ecosystems.     

Effects of Exotic Plant Species on Soil Properties in Hardwood Forests of New Jersey

Two exotic plant species, Berberis thunbergii and Microstegium vimineum, recently have invaded deciduous hardwood forests in the Northeast. We examined changes in soil properties that may be associated with this invasion in three parks in northern New Jersey. In each park, we collected soil and vegetation data along transects that were established across heavily infested areas and extended into uninvaded forest. The data were analyzed statistically by ANOVA and Canonical Correspondence Analysis (CCA). Significant differences were found between invaded and uninvaded plots in both soil and vegetation characteristics. Invaded areas have fewer oaks (Quercus spp.) in the canopy, and lack the native understory shrubs (Vaccinium spp.). The pH of soils in the invaded areas is significantly higher than in the uninvaded areas, and the litter and organic horizons are thinner. The data cannot show that the exotic species have caused these changes. However, the occurrence of contrasting soils in adjacent areas of native vegetation, with no evidence of differences in land-use history between areas, suggests that such a cause-and-effect relationship exists. We propose a feedback loop involving the exotic plants, and the presence of earthworms to explain these dramatic soil differences.