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1.
Fine root growth phenology,production, and turnover in a northern hardwood forest ecosystem 总被引:21,自引:2,他引:19
A large part of the nutrient flux in deciduous forests is through fine root turnover, yet this process is seldom measured. As part of a nutrient cycling study, fine root dynamics were studied for two years at Huntington Forest in the Adirondack Mountain region of New York, USA. Root growth phenology was characterized using field rhizotrons, three methods were used to estimate fine root production, two methods were used to estimate fine root mortality, and decomposition was estimated using the buried bag technique. During both 1986 and 1987, fine root elongation began in early April, peaked during July and August, and nearly ceased by mid-October. Mean fine root ( 3 mm diameter) biomass in the surface 28-cm was 2.5 t ha–1 and necromass was 2.9 t ha–1. Annual decomposition rates ranged from 17 to 30% beneath the litter and 27 to 52% at a depth of 10 cm. Depending on the method used for estimation, fine root production ranged from 2.0 to 2.9 t ha–1, mortality ranged from 1.8 to 3.7 t ha–1 yr–1, and decomposition was 0.9 t ha–1 yr–1. Thus, turnover ranged from 0.8 to 1.2 yr–1. The nutrients that cycled through fine roots annually were 4.5–6.1 kg Ca, 1.1–1.4 kg Mg, 0.3–0.4 kg K, 1.2–1.7 kg P, 20.3–27.3 kg N, and 1.8–2.4 kg S ha–1. Fine root turnover was less important than leaf litterfall in the cycling of Ca and Mg and was similar to leaf litterfall in the amount of N, P, K and S cycled. 相似文献
2.
Naomi Ish-Shalom Leonel da Silveira Lobo Sternberg Michael Ross Joseph O'Brien Laura Flynn 《Oecologia》1992,92(1):108-112
Summary Predawn water potential of representative plant species, together with stable isotope composition of stem water and potential water sources were investigated in four low-elevation tropical hardwood hammocks in the Lower Florida Keys, during a one year period. Hammock species had the lowest water potentials when soil water content was low and/or soil salinity was high, but differences in groundwater salinity had no effect on the water potential. Comparison of D/H ratio of plant stem water with soil and ground water corroborates the conclusion that they are primarily utilizing soil water and not groundwater. Thus, tropical hardwood hammocks are buffered from saline groundwater, and are able to thrive in areas where groundwater salinity is as high as 25. The effect of sea level rise on these forests may depend more on changes in the frequency of tidal inundation of the soil surface than on changes in groundwater salinity. 相似文献
3.
Seasonal and spatial patterns of S,Ca, and N dynamics of a Northern Hardwood forest ecosystem 总被引:1,自引:1,他引:0
Seasonal dynamics of S, Ca and N were examined at the Huntington Forest, a northern hardwood ecosystem in the central Adirondacks
of New York for a period of 34 months (1985–1988). Solute concentrations and fluxes in bulk precipitation, throughfall (TF)
and leachates from the forest floor, E horizon and B horizon were quantified. Both above and below-ground elemental fluxes
mediated by vegetation (e.g. uptake, litter inputs, and fine roots production) were also determined. The roles of abiotic
and biotic processes were ascertained based on both changes in solute concentrations through the strata of the ecosystem as
well as differences between dormant and growing seasons. Concentrations of SO4
2−, NO3
−, NH4
+ and Ca2+ were greater in TF than precipitation. Forest floor leachates had greater concentrations of SO4
2−, NO3
− + NH4
+ and Ca2+ (9, 6 and 77 μeq L−1, respectively) than TF. There were differences in concentrations of ions in leachates from the forest floor between the dormant
and growing seasons presumably due to vegetation uptake and microbial immobilization. Concentrations and fluxes of NO3
− and NH; were greatest in early spring followed by a rapid decline which coincided with a demand for N by vegetation in late
spring. Vegetation uptake (44.7 kg N ha−1 yr−1 ) could account for the low leaching rates of N03
−. Within the mineral soil, changes with soil depth and the absence of seasonal patterns suggest that cation exchange (Ca+) or anion sorption (SO4
2−) are primarily responsible for regulating solute concentrations. The increase in SO4
2− concentration after leachates passed through the mineral soil may be attributed to desorption of sulfate that was adsorbed
during an earlier period when SO4
2− concentrations would have been greater due to elevated S inputs. 相似文献
4.
John C. Denton Charlotte L. Roy Gregory J. Soulliere Bradly A. Potter 《The Journal of wildlife management》2012,76(2):422-432
Clearing of hardwood forests was widespread in the north central region of the United States at the turn of the 20th century, but largely subsided by the 1920s. Hardwood trees in the region have since regenerated and matured into sizes capable of producing nest cavities suitable for cavity-nesting ducks. We estimated regional nest-site abundance for cavity-nesting ducks during 2008, 2018, and 2028 from cavity density and tree-abundance estimates obtained at 4 hardwood forest sites in conjunction with Forest Inventory and Analysis data and tree-growth modeling software from the United States Forest Service (Forest Vegetation Simulator). Land cover data were used to determine area of hardwood forests ≤0.5 km, 0.5–1 km, 1–1.5 km, 1.5–2 km, and >2 km from wetlands and open water available to cavity-nesting ducks. We estimated 13.2 million, 17.0 million, 19.0 million, and 20.1 million potential duck nest cavities available ≤0.5 km, ≤1 km, ≤1.5 km, and ≤2 km of water, respectively, in the region and predicted nest cavity abundance will increase 41% from 2008 to 2028. Hardwood forests in Indiana, Michigan, Ohio, and Wisconsin currently have the highest abundances of potential nest sites, but cavity-bearing forests in Minnesota, Michigan, and Wisconsin were more commonly proximate to wetlands and open water. Because current and future estimates indicate sufficient nest sites to support growing cavity-nesting duck populations in the north central United States, we recommend regional management efforts focus on protecting, restoring, and maintaining quality wetlands in proximity to hardwood forests. © 2011 The Wildlife Society. 相似文献
5.
A greenhouse mesocosm experiment, representing earthworm-free North American Acer-dominated forest floor and soil conditions, was used to examine the individual and combined effects of initial invasion by
three European earthworm species (Dendrobaena octaedra, Lumbricus rubellus and Lumbricus terrestris) on the forest floor and upper soil horizons, N and P availability, and the mortality and biomass of four native understory
plant species (Acer saccharum, Aquilegia canadensis, Aralia racemosa, and Carex pensylvanica). All the three earthworm species combined caused larger impacts on most variables measured than any single earthworm species.
These included loss of O horizon mass, decreased thickness of the O horizon and increased thickness of the A horizon, and
higher availability of N and P. The latter finding differs from field reports where nutrients were less available after invasion,
and probably represents an initial transient increase in nutrient supply as earthworms consume and incorporate the O horizon
into the A horizon. Earthworms also increased mortality of plants and decreased total mesocosm plant biomass, but here the
impact of all the three earthworm species was no greater than that of L. terrestris and/or L. rubellus alone. This study corroborates field studies that European earthworm invasions alter North American forest ecosystem processes
by initiating a cascade of impacts on plant community composition and soil properties. 相似文献
6.
Kasuga J Hashidoko Y Nishioka A Yoshiba M Arakawa K Fujikawa S 《Plant, cell & environment》2008,31(9):1335-1348
Xylem parenchyma cells (XPCs) of boreal hardwood species adapt to sub-freezing temperatures by deep supercooling to maintain a liquid state of intracellular water near −40 °C. Our previous study found that crude xylem extracts from such tree species exhibited anti-ice nucleation activity to promote supercooling of water. In the present study, thus, we attempted to identify the causative substances of supercooling. Crude xylem extracts from katsura tree ( Cercidiphyllum japonicum ), of which XPCs exhibited deep supercooling to −40 °C, were prepared by methanol extraction. The crude extracts were purified by liquid–liquid extraction and then by silica gel column chromatography. Although all the fractions obtained after each purification step exhibited some levels of anti-ice nucleation activity, only the most active fraction was retained to proceed to the subsequent level of purification. High-performance liquid chromatography (HPLC) analysis of a fraction with the highest level of activity revealed four peaks with high levels of anti-ice nucleation activity in the range of 2.8–9.0 °C. Ultraviolet (UV), mass and nuclear magnetic resonance (NMR) spectra revealed that these four peaks corresponded to quercetin-3- O - β -glucoside (Q3G), kaempferol-7- O - β -glucoside (K7G), 8-methoxykaempferol-3- O - β -glucoside (8MK3G) and kaempferol-3- O - β -glucoside (K3G). Microscopic observations confirmed the presence of flavonoids in cytoplasms of XPCs. These results suggest that diverse kinds of anti-ice nucleation substances, including flavonol glycosides, may have important roles in deep supercooling of XPCs. 相似文献
7.
European earthworms are colonizing worm-free hardwood forests across North America. Leading edges of earthworm invasion in
forests of northern Minnesota provide a rare opportunity to document changes in soil characteristics as earthworm invasions
are occurring. Across leading edges of earthworm invasion in four northern hardwood stands, increasing total earthworm biomass
was associated with rapid disappearance of the O horizon. Concurrently, the thickness, bulk density and total soil organic
matter content of the A horizon increased, and it’s percent organic matter and fine root density decreased. Different earthworm
species assemblages influenced the magnitude and type of change in these soil parameters. Soil N and P availability were lower
in plots with high earthworm biomass compared to plots with low worm biomass. Decreases in soil nitrogen availability associated
with high earthworm biomass were reflected in decreased foliar nitrogen content for Carex pensylvanica, Acer saccharum and Asarum canadense but increased foliar N for Athyrium felix-femina. Overall, high earthworm biomass resulted in increased foliar carbon to nitrogen ratios. The effects of earthworm species
assemblages on forest soil properties are related to their feeding and burrowing habits in addition to effects related to
total biomass. The potential for large ecosystem consequences following exotic earthworm invasion has only recently been recognized
by forest ecologists. In the face of rapid change and multiple pressures on native forest ecosystems, the impacts of earthworm
invasion on forest soil structure and function must be considered. 相似文献
8.
Field‐grown yellow‐poplar (Liriodendron tulipifera L.) werefumigated from May to October in 1992–96 within open‐topchambers to determine the impact of ozone (O3) aloneor combined with elevated carbon dioxide (CO2) on saplinggrowth. Treatments were replicated three times and included: charcoal‐filteredair (CF); 1 × ambient ozone (1 × O3);1·5 × ambient ozone (1·5 × O3);1·5 × ambient ozone plus 350 p.p.m.carbon dioxide (1·5 × O3 + CO2)(target of 700 p.p.m. CO2); and open‐air chamberlessplot (OA). After five seasons, the total cumulative O3 exposure (SUM00 = sumof hourly O3 concentrations during the study) rangedfrom 145 (CF) to 861 (1·5 × O3) p.p.m. × h (partsper million hour). Ozone had no statistically significant effecton yellow‐poplar growth or biomass, even though total root biomasswas reduced by 13% in the 1·5 × O3‐exposedsaplings relative to CF controls. Although exposure to 1·5 × O3 + CO2 hada stimulatory effect on yearly basal area growth increment aftertwo seasons, significant increases in shoot and root biomass (~ 60% increaserelative to all others) were not detected until the fifth season.After five seasons, the yearly basal area growth increment of saplingsexposed to 1·5 × O3 + CO2‐air increasedby 41% relative to all others. Based on this multi‐yearstudy, it appears that chronic O3 effects on yellow‐poplargrowth are limited and slow to manifest, and are consistent withprevious studies that show yellow‐poplar growth is not highly responsiveto O3 exposure. In addition, these results show thatenriched CO2 may ameliorate the negative effects of elevatedO3 on yellow‐poplar shoot growth and root biomass underfield conditions. 相似文献
9.
Intersite relationships among nematode communities of 18 Indiana mixed hardwood stands of varying composition, soils, physiography and past management practices were determined by community ordination techniques. All sites were sampled in April, July and October of 1968 and 1969, and ordinations were based on the number of individuals of each nematode species at each site at each sampling period. The resulting groupings correlated well with groupings based on forest types and successional stages of the tree communities at the sites, and also with groupings based on well-defined soil types. Results were similar to those obtained previously with a resemblance equation which used qualitative data only; but the present study provided more information on species associations and relationships and ecological distance between sites. 相似文献
10.