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1.
Responses of sawgrass and spikerush to variation in hydrologic drivers and salinity in Southern Everglades marshes 总被引:3,自引:3,他引:0
Daniel L. Childers David Iwaniec Damon Rondeau Gustavo Rubio Emilie Verdon Christopher J. Madden 《Hydrobiologia》2006,569(1):273-292
Aboveground net primary production (ANPP) by the dominant macrophyte and plant community composition are related to the changing
hydrologic environment and to salinity in the southern Everglades, FL, USA. We present a new non-destructive ANPP technique
that is applicable to any continuously growing herbaceous system. Data from 16 sites, collected from 1998 to 2004, were used
to investigate how hydrology and salinity controlled sawgrass (Cladium jamaicense Crantz.) ANPP. Sawgrass live biomass showed little seasonal variation and annual means ranged from 89 to 639 gdw m−2. Mortality rates were 20–35% of live biomass per 2 month sampling interval, for biomass turnover rates of 1.3–2.5 per year.
Production by C. jamaicense was manifest primarily as biomass turnover, not as biomass accumulation. Rates typically ranged from 300 to 750 gdw m−2 year−1, but exceeded 1000 gdw m−2 year−1 at one site and were as high as 750 gdw m−2 year−1 at estuarine ecotone sites. Production was negatively related to mean annual water depth, hydroperiod, and to a variable
combining the two (depth-days). As water depths and hydroperiods increased in our southern Everglades study area, sawgrass
ANPP declined. Because a primary restoration goal is to increase water depths and hydroperiods for some regions of the Everglades,
we investigated how the plant community responded to this decline in sawgrass ANPP. Spikerush (Eleocharis sp.) was the next most prominent component of this community at our sites, and 39% of the variability in sawgrass ANPP was
explained by a negative relationship with mean annual water depth, hydroperiod, and Eleocharis sp. density the following year. Sawgrass ANPP at estuarine ecotone sites responded negatively to salinity, and rates of production
were slow to recover after high salinity years. Our results suggest that ecologists, managers, and the public should not necessarily
interpret a decline in sawgrass that may result from hydrologic restoration as a negative phenomenon. 相似文献
2.
McCormick Paul V. Shuford III Robert B. E. Backus John G. Kennedy William C. 《Hydrobiologia》1997,362(1-3):185-210
We sampled periphyton in dominant habitats at oligotrophic and eutrophic sites in the northern Everglades during the wet and
the dryseasons to determine the effects of nutrient enrichment on periphytonbiomass, taxonomic composition, productivity,
and phosphorus storage. Arealbiomass was high (100–1600 g ash-free dry mass [AFDM]m−2) in oligotrophic sloughs and in stands of the emergentmacrophyte Eleocharis cellulosa, but was low in adjacent stands of
sawgrass,Cladium jamaicense (7–52 g AFDM m−2). Epipelon biomasswas high throughout the year at oligotrophic sites whereas epiphyton andmetaphyton biomass varied seasonally
and peaked during the wet season.Periphyton biomass was low (3–68 g AFDM m−2) and limitedto epiphyton and metaphyton in open-water habitats at eutrophic sites andwas undetectable in cattail stands (Typha
domingensis) that covered morethan 90% of the marsh in these areas. Oligotrophic periphytonassemblages exhibited strong seasonal
shifts in species composition and weredominated by cyanobacteria (e.g., Chroococcus turgidus, Scytonema hofmannii)during the
wet season and diatoms (e.g. Amphora lineolata, Mastogloiasmithii) during the dry season. Eutrophic assemblages were dominated
byCyanobacteria (e.g., Oscillatoria princeps) and green algae (e.g., Spirogyraspp.) and exhibited comparatively little seasonality.
Biomass-specific grossprimary productivity (GPP) of periphyton assemblages in eutrophic openwaters was higher than for comparable
slough assemblages, but areal GPP wassimilar in these eutrophic (0.9–9.1 g C m−2d−1) and oligotrophic (1.75–11.49 g C m−2d−1) habitats. On a habitat-weighted basis, areal periphytonGPP was 6- to 30-fold lower in eutrophic areas of the marsh due to
extensiveTypha stands that were devoid of periphyton. Periphyton at eutrophic siteshad higher P content and uptake rates than
the oligotrophic assemblage, butstored only 5% as much P because of the lower areal biomass.Eutrophication in the Everglades
has resulted in a decrease in periphytonbiomass and its contribution to marsh primary productivity. These changesmay have
important implications for efforts to manage this wetland in asustainable manner.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
Daniel L. Childers 《Hydrobiologia》2006,569(1):531-544
This paper synthesizes research conducted dusring the first 5–6 years of the Florida Coastal Everglades Long-Term Ecological
Research Program (FCE LTER). My objectives are to review our research to date, and to present a new central theme and conceptual
approach for future research. Our research has focused on understanding how dissolved organic matter (DOM) from upstream oligotrophic
marshes interacted with a marine source of the limiting nutrient, phosphorus (P), to control productivity in the oligohaline
estuarine ecotone. We have been working along freshwater to marine transects in two drainage basins located in Everglades
National Park (ENP). The Shark River Slough transect (SRS) has a direct connection to the Gulf of Mexico, providing this estuarine
ecotone with a source of marine P. The oligohaline ecotone along our southern Everglades transect (TS/Ph), however, is separated
from this marine P source by the Florida Bay estuary. We originally hypothesized an ecosystem productivity peak in the SRS
ecotone, driven by the interaction of marine P and Everglades DOM, but no such productivity peak in the TS/Ph ecotone because
of this lack of marine P. Our research to date has tended to show the opposite pattern, however, with many ecosystem components
showing enhanced productivity in the TS/Ph ecotone, but not in the SRS ecotone. Water column P concentrations followed a similar
pattern, with unexpectedly high P in the TS/Ph ecotone during the dry season. Our organic geochemical research has shown that
Everglades DOM is more refractory than originally hypothesized. We have also begun to understand the importance of detrital
organic matter production and transport to ecotone dynamics and as the base of aquatic food webs. Our future research will
build on this substantial body of knowledge about these oligotrophic estuaries. We will direct our efforts more strongly on
biophysical dynamics in the oligohaline ecotone regions. Specifically, we will be focusing on inputs to these regions from
four primary water sources: freshwater Everglades runoff, net precipitation, marine inputs, and groundwater. We are hypothesizing
that dry season groundwater inputs of P will be particularly important to TS/Ph ecotone dynamics because of longer water residence
times in this area. Our organic geochemical, biogeochemical, and ecosystem energetics work will focus more strongly on the
importance of detrital organics and will take advantage of a key Everglades Restoration project, scheduled for 2008 or 2009,
that will increase freshwater inputs to our SRS transect only. Finally, we will also begin to investigate the human dimensions
of restoration, and of a growing population in south Florida that will become increasingly dependent on the Everglades for
critical ecosystem services (including fresh water) even as its growth presents challenges to Everglades sustainability. 相似文献
4.
基于2008—2016年青海海北站9年净初级生产力及气候因子监测数据,分析了青藏高原高寒小嵩草草甸和高寒金露梅灌丛两种植被净初级生产力年际动态,并探讨了气候因子对其影响及其不同土层深度根系周转值特征。结果表明:(1)年际尺度上,小嵩草草甸地上净初级生产力表现为显著增加趋势,增幅为7.02 g m~(-2) a~(-1),而金露梅灌丛地上净初级生产力相对较为稳定;对于其地下净初级生产力和总生产力,小嵩草草甸和金露梅灌丛均表现为增加趋势(P0.05),9年间小嵩草草甸地上、地下和总净初级生产力平均值分别为(217.55±9.95)、(1882.75±161.33) g m~(-2) a~(-1)和(2100.30±163.38) g m~(-2) a~(-1),金露梅灌丛地上、地下和总净初级生产力9年间平均值分别为(256.27±11.4)、(1614.31±173.03) g m~(-2) a~(-1)和(1870.58±177.93) g m~(-2) a~(-1)。(2)不同植被类型地上净初级生产力对气候因素响应不同,金露梅灌丛地上净初级生产力主要受温度影响,而温度对小嵩草草甸地上净初级生产力无显著影响。此外,降水不是限制高寒生态系统草地地上净初级生产力主要因子,相比于降水影响,高寒生态系统地上净初级生产力更受温度调控。(3)年均温和年降水对金露梅灌丛和小嵩草草甸地下净初级生产力均无显著影响(P0.05),表明高寒生态系统,其地下生产力受外界气候条件变化影响微弱,是一个稳定的碳库。(4)两种植被类型其根系周转值均随着土壤深度的增加呈逐渐增加趋势,且高寒灌丛根系周转值明显高于高寒草甸根系周转值。研究表明,在全球气候变暖背景下将会增加金露梅灌丛地上净初级生产力,而对小嵩草草甸地上净初级生产力无显著影响。 相似文献
5.
Sparkle L. Malone Christina L. Staudhammer Steven F. Oberbauer Paulo Olivas Michael G. Ryan Jessica L. Schedlbauer Henry W. Loescher Gregory Starr 《PloS one》2014,9(12)
This research examines the relationships between El Niño Southern Oscillation (ENSO), water level, precipitation patterns and carbon dioxide (CO2) exchange rates in the freshwater wetland ecosystems of the Florida Everglades. Data was obtained over a 5-year study period (2009–2013) from two freshwater marsh sites located in Everglades National Park that differ in hydrology. At the short-hydroperiod site (Taylor Slough; TS) and the long-hydroperiod site (Shark River Slough; SRS) fluctuations in precipitation patterns occurred with changes in ENSO phase, suggesting that extreme ENSO phases alter Everglades hydrology which is known to have a substantial influence on ecosystem carbon dynamics. Variations in both ENSO phase and annual net CO2 exchange rates co-occurred with changes in wet and dry season length and intensity. Combined with site-specific seasonality in CO2 exchanges rates, El Niño and La Niña phases magnified season intensity and CO2 exchange rates at both sites. At TS, net CO2 uptake rates were higher in the dry season, whereas SRS had greater rates of carbon sequestration during the wet season. As La Niña phases were concurrent with drought years and extended dry seasons, TS became a greater sink for CO2 on an annual basis (−11 to −110 g CO2 m−2 yr−1) compared to El Niño and neutral years (−5 to −43.5 g CO2 m−2 yr−1). SRS was a small source for CO2 annually (1.81 to 80 g CO2 m−2 yr−1) except in one exceptionally wet year that was associated with an El Niño phase (−16 g CO2 m−2 yr−1). Considering that future climate predictions suggest a higher frequency and intensity in El Niño and La Niña phases, these results indicate that changes in extreme ENSO phases will significantly alter CO2 dynamics in the Florida Everglades. 相似文献
6.
Aboveground net primary production (ANPP) and leaf-area index (LAI) of lodgepole pine (Pinus contorta var. latifolia Engelm. ex Wats.) saplings and aboveground productivity of herbaceous vegetation components were determined 9 years after
the 1988 fires in Yellowstone National Park (YNP). Measurements were made in four sites representing a wide range of early
postfire vegetation present in YNP, including high-density lodgepole pine, low-density lodgepole pine, and two nonforest stands.
LAI of the pine saplings and total ANPP (trees plus herbs) generally increased with increasing sapling density, from 0.002
m2 m−
2 and 0.25 Mg ha−
1 year−
1 in the infertile nonforest stand (100 pine saplings ha−
1) to 1.8 m2 m−
2 and 4.01 Mg ha−
1 year−
1 in the high-density pine stand (62,800 saplings ha−
1). Aboveground herbaceous productivity was not strongly correlated with sapling density, but appeared to be influenced by
soil fertility. In the high-density pine stand, tree ANPP and LAI were within the lower range of values reported for similar
mature coniferous forests. This finding suggests that at least some ecosystem processes (related to ANPP and LAI) may have
nearly recovered after only 9 years of postfire succession, in at least some of the young forests developing after the 1988
Yellowstone fires.
Received 7 April 1998; accepted 1 December 1998. 相似文献
7.
Estimates of biomass and primary productivity in a high-altitude maple forest of the west central Himalayas 总被引:4,自引:0,他引:4
S. C. Garkoti 《Ecological Research》2008,23(1):41-49
The paper describes the biomass and productivity of maple (Acer cappadocicum) forest occurring at an altitude of 2,750 m in the west central Himalayas. Total vegetation biomass was 308.3 t ha−1, of which the tree layer contributed the most, followed by herbs and shrubs. The seasonal forest-floor litter mass varied
between 5.4 t ha−1 (in rainy season) and 6.6 t ha−1 (in winter season). The annual litter fall was 6.2 t ha−1, of which leaf litter contributed the largest part (59% of the total litter fall). Net primary productivity of total vegetation
was 19.5 t ha−1 year−1. The production efficiency of leaves (net primary productivity/leaf mass) was markedly higher (2.9 g g−1 foliage mass year−1) than those of the low-altitude forests of the region. 相似文献
8.
Edward Castañeda-Moya Robert R. Twilley Victor H. Rivera-Monroy Brian D. Marx Carlos Coronado-Molina Sharon M. L. Ewe 《Ecosystems》2011,14(7):1178-1195
Patterns of mangrove vegetation in two distinct basins of Florida Coastal Everglades (FCE), Shark River estuary and Taylor
River Slough, represent unique opportunities to test hypotheses that root dynamics respond to gradients of resources, regulators,
and hydroperiod. We propose that soil total phosphorus (P) gradients in these two coastal basins of FCE cause specific patterns
in belowground biomass allocation and net primary productivity that facilitate nutrient acquisition, but also minimize stress
from regulators and hydroperiod in flooded soil conditions. Shark River basin has higher P and tidal hydrology with riverine
mangroves, in contrast to scrub mangroves of Taylor basin with more permanent flooding and lower P across the coastal landscape.
Belowground biomass (0–90 cm) of mangrove sites in Shark River and Taylor River basins ranged from 2317 to 4673 g m−2, with the highest contribution (62–85%) of roots in the shallow root zone (0–45 cm) compared to the deeper root zone (45–90 cm).
Total root productivity did not vary significantly among sites and ranged from 407 to 643 g m−2 y−1. Root production in the shallow root zone accounted for 57–78% of total production. Root turnover rates ranged from 0.04
to 0.60 y−1 and consistently decreased as the root size class distribution increased from fine to coarse roots, indicating differences
in root longevity. Fine root biomass was negatively correlated with soil P density and frequency of inundation, whereas fine
root turnover decreased with increasing soil N:P ratios. Lower P availability in Taylor River basin relative to Shark River
basin, along with higher regulator and hydroperiod stress, confirms our hypothesis that interactions of stress from resource
limitation and long duration of hydroperiod account for higher fine root biomass along with lower fine root production and
turnover. Because fine root production and organic matter accumulation are the primary processes controlling soil formation
and accretion in scrub mangrove forests, root dynamics in the P-limited carbonate ecosystem of south Florida have a major
controlling role as to how mangroves respond to future impacts of sea-level rise. 相似文献
9.
Comparative study of periphyton community structure in long and short-hydroperiod Everglades marshes 总被引:1,自引:0,他引:1
The Florida Everglades is a mosaic of short and long-hydroperiod marshes that differ in the depth, duration, and timing of
inundation. Algae are important primary producers in widespread Everglades’ periphyton mats, but relationships of algal production
and community structure to hydrologic variability are poorly understood. We quantified differences in algal biomass and community
structure between periphyton mats in 5 short and 6 long-hydroperiod marshes in Everglades National Park (ENP) in October 2000.
We related differences to water depth and total phosphorus (TP) concentration in the water, periphyton and soils. Long and
short-hydroperiod marshes differed in water depth (73 cm vs. 13 cm), periphyton TP concentrations (172μg g−1 vs. 107 μg g−1, respectively) and soil TP (284 μg g−1 vs. 145 μg g−1). Periphyton was abundant in both marshes, with short-hydroperiod sites having greater biomass than long-hydroperiod sites
(2936 vs. 575 grams ash-free dry mass m−2). A total of 156 algal taxa were identified and separated into diatom (68 species from 21 genera) and “soft algae” (88 non-diatom
species from 47 genera) categories for further analyses. Although diatom total abundance was greater in long-hydroperiod mats,
diatom species richness was significantly greater in short- hydroperiod periphyton mats (62 vs. 47 diatom taxa). Soft algal
species richness was greater in long-hydroperiod sites (81 vs. 67 soft algae taxa). Relative abundances of individual taxa
were significantly different among the two site types, with soft algal distributions being driven by water depth, and diatom
distributions by water depth and TP concentration in the water and periphyton. Periphyton communities differ between short
and long-hydroperiod marshes, but because they share many taxa, alterations in hydroperiod could rapidly promote the alternate
community.
Electronic supplementary material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
10.
Long-term management plans for restoration of natural flow conditions through the Everglades increase the importance of understanding
potential nutrient impacts of increased freshwater delivery on Florida Bay biogeochemistry. Planktonic communities respond
quickly to changes in water quality, thus spatial variability in community composition and relationships to nutrient parameters
must be understood in order to evaluate future downstream impacts of modifications to Everglades hydrology. Here we present
initial results combining flow cytometry analyses of phytoplankton and bacterial populations (0.1–50 μm size fraction) with measurements of δ13C and δ15N composition and dissolved inorganic nutrient concentrations to explore proxies for planktonic species assemblage compositions
and nutrient cycling. Particulate organic material in the 0.1–50 μm size fraction was collected from five stations in Northeastern and Western Florida Bay to characterize spatial variability
in species assemblage and stable isotopic composition. A dense bloom of the picocyanobacterium, Synechococcus elongatus, was observed at Western Florida Bay sites. Smaller Synechococcus sp. were present at Northeast sites in much lower abundance. Bacteria and detrital particles were also more abundant at Western
Florida Bay stations than in the northeast region. The highest abundance of detritus occurred at Trout Creek, which receives
freshwater discharge from the Everglades through Taylor Slough. In terms of nutrient availability and stable isotopic values,
the S. elongatus population in the Western bay corresponded to low DIN (0.5 μM NH
4
+
; 0.2 μM NO
3
−
) concentrations and depleted δ15N signatures ranging from +0.3 to +0.8‰, suggesting that the bloom supported high productivity levels through N2-fixation. δ15N values from the Northeast bay were more enriched (+2.0 to +3.0‰), characteristic of N-recycling. δ13C values were similar for all marine Florida Bay stations, ranging from −17.6 to −14.4‰, however were more depleted at the
mangrove ecotone station (−25.5 to −22.3‰). The difference in the isotopic values reflects differences in carbon sources.
These findings imply that variations in resource availability and nutrient sources exert significant control over planktonic
community composition, which is reflected by stable isotopic signatures. 相似文献
11.
To determine relationships between soil nutrient status and known gradients in primary production, we collected and analyzed
soils from 17 LTER sampling sites along two transects through south Florida wetland ecosystems. Through upstream freshwater
marsh, a middle reach including the oligohaline marsh/mangrove ecotone, and downstream estuarine habitats, we observed systematic
variation in soil bulk density, organic content, and pools of phosphorus (P), inorganic sulfur, and extractable iron. Consistent
with observed differences in wetland productivity known to be limited by P availability, total P averaged ~200 μg g dw−1 in soils from the eastern Taylor Slough/Panhandle and was on average three times higher in soils from the western Shark River
Slough. Along both transects, the largest pool of phosphorus was the inorganic, carbonate-bound fraction, comprising 35–44%
of total P. Greater than 90% of the total inorganic sulfur pool in these south Florida wetland soils was extracted as pyrite.
Freshwater marsh sites typically were lower in pyrite sulfur (0.2–0.8 mg g dw−1) relative to marsh/mangrove ecotone and downstream estuary sites (0.5–2.9 mg g dw−1). Extractable iron in freshwater marsh soils was significantly higher from the Taylor Slough/Panhandle transect (3.2 mg g dw−1) relative to the western Shark River Slough transect (1.1 mg g dw−1), suggesting spatial variation in sources and/or depositional environments for iron. Further, these soil characteristics
represent the collective, integrated signal of ecosystem structure, so any long-term changes in factors like water flow or
water quality may be reflected in changes in bulk soil properties. Since the objective of current Everglades restoration initiatives
is the enhancement and re-distribution of freshwater flows through the south Florida landscape, the antecedent soil conditions
reported here provide a baseline against which future, post-restoration measurements can be compared. 相似文献
12.
Soil Nutrients Limit Fine Litter Production and Tree Growth in Mature Lowland Forest of Southwestern Borneo 总被引:1,自引:0,他引:1
Efforts to improve models of terrestrial productivity and to understand the function of tropical forests in global carbon
cycles require a mechanistic understanding of spatial variation in aboveground net primary productivity (ANPP) across tropical
landscapes. To help derive such an understanding for Borneo, we monitored aboveground fine litterfall, woody biomass increment
and ANPP (their sum) in mature forest over 29 months across a soil nutrient gradient in southwestern Kalimantan. In 30 (0.07 ha)
plots stratified throughout the watershed (∼340 ha, 8–190 m a.s.l.), we measured productivity and tested its relationship
with 27 soil parameters. ANPP across the study area was among the highest reported for mature lowland tropical forests. Aboveground
fine litterfall ranged from 5.1 to 11.0 Mg ha−1 year−1 and averaged 7.7 ± 0.4 (mean ± 95 C.I.). Woody biomass increment ranged from 5.8 to 23.6 Mg ha−1 year−1 and averaged 12.0 ± 2.0. Growth of large trees (≥60 cm dbh) contributed 38–82% of plot-wide biomass increment and explained
92% of variation among plots. ANPP, the sum of these parameters, ranged from 11.1 to 32.3 Mg ha−1 year−1 and averaged 19.7 ± 2.2. ANPP was weakly related to fine litterfall (r
2 = 0.176), but strongly related to growth of large trees at least 60 cm dbh (r
2 = 0.848). Adjusted ANPP after accounting for apparent “mature forest bias” in our sampling method was 17.5 ± 1.2 Mg ha−1 year−1.Relating productivity measures to soil parameters showed that spatial patterning in productivity was significantly related
to soil nutrients, especially phosphorus (P). Fine litterfall increased strongly with extractable P (r
2 = 0.646), but reached an asymptote at moderate P levels, whereas biomass increment (r
2 = 0.473) and ANPP (r
2 = 0.603) increased linearly across the gradient. Biomass increment of large trees was more frequently and strongly related to
nutrients than small trees, suggesting size dependency of tree growth on nutrients. Multiple linear regression confirmed the
leading importance of soil P, and identified Ca as a potential co-limiting factor. Our findings strongly suggest that (1)
soil nutrients, especially P, limit aboveground productivity in lowland Bornean forests, and (2) these forests play an important,
but changing role in carbon cycles, as canopy tree logging alters these terrestrial carbon sinks.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
13.
Energy flow and subsidies associated with the complex life cycle of ambystomatid salamanders in ponds and adjacent forest in southern Illinois 总被引:1,自引:0,他引:1
Breeding adults and metamorphosing larval amphibians transfer energy between freshwater and terrestrial ecosystems during
seasonal migrations and emergences, although rarely has this been quantified. We intensively sampled ambystomatid salamander
assemblages (Ambystoma opacum,A. maculatum, and A. tigrinum) in five forested ponds in southern Illinois to quantify energy flow associated with egg deposition, larval production, and
emergence of metamorphosed larvae. Oviposition by female salamanders added 7.0–761.4 g ash-free dry mass (AFDM) year−1 to ponds (up to 5.5 g AFDM m−2 year−1). Larval production ranged from 0.4 to 7.4 g AFDM m−2 year−1 among populations in three ponds that did not dry during larval development, with as much as 7.9 g AFDM m−2 year−1 produced by an entire assemblage. Mean larval biomass during cohort production intervals in these three ponds ranged from
0.1 to 2.3 g AFDM m−2 and annual P/B (production/biomass) ranged from 4 to 21 for individual taxa. Emergent biomass averaged 10% (range=2–35%) of larval production;
larval mortality within ponds accounted for the difference. Hydroperiod and intraguild predation limited larval production
in some ponds, but emerging metamorphs exported an average of 70.0±33.9 g AFDM year−1 (range=21.0–135.2 g AFDM year−1) from ponds to surrounding forest. For the three ponds where larvae survived to metamorphosis, salamander assemblages provided
an average net flux of 349.5±140.8 g AFDM year−1 into pond habitats. Among all ponds, net flux into ponds was highest for the largest pond and decreased for smaller ponds
with higher perimeter to surface area ratios (r
2 =0.94, P<0.05, n=5). These results are important in understanding the multiple functional roles of salamanders and the impact of amphibian
population declines on ecosystems.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
14.
CO2 and N-fertilization effects on fine-root length, production, and mortality: a 4-year ponderosa pine study 总被引:1,自引:0,他引:1
We conducted a 4-year study of juvenile Pinus ponderosa fine root (≤2 mm) responses to atmospheric CO2 and N-fertilization. Seedlings were grown in open-top chambers at three CO2 levels (ambient, ambient+175 μmol/mol, ambient+350 μmol/mol) and three N-fertilization levels (0, 10, 20 g m−2 year−1). Length and width of individual roots were measured from minirhizotron video images bimonthly over 4 years starting when the seedlings were 1.5 years old. Neither CO2 nor N-fertilization treatments affected the seasonal patterns of root production or mortality. Yearly values of fine-root length standing crop (m m−2), production (m m−2 year−1), and mortality (m m−2 year−1) were consistently higher in elevated CO2 treatments throughout the study, except for mortality in the first year; however, the only statistically significant CO2 effects were in the fine-root length standing crop (m m−2) in the second and third years, and production and mortality (m m−2 year−1) in the third year. Higher mortality (m m−2 year−1) in elevated CO2 was due to greater standing crop rather than shorter life span, as fine roots lived longer in elevated CO2. No significant N effects were noted for annual cumulative production, cumulative mortality, or mean standing crop. N availability did not significantly affect responses of fine-root standing crop, production, or mortality to elevated CO2. Multi-year studies at all life stages of trees are important to characterize belowground responses to factors such as atmospheric CO2 and N-fertilization. This study showed the potential for juvenile ponderosa pine to increase fine-root C pools and C fluxes through root mortality in response to elevated CO2. 相似文献
15.
Light irradiation had remarkable effects on callus growth of Oldenlandia affinis with an optimum intensity of 35 μmol m−2 s−1. Biosynthesis of kalata B1, the main cyclic peptide in O. affinis, was induced and triggered with rising irradiation intensities. The highest concentration of kalata B1, 0.49 mg g−1 DW characterised by the maximum productivity of 3.88 μg per litre and day was analysed at 120 μmol m−2 s−1, although callus growth was repressed. The light saturation point was established to be 35 μmol m−2 s−1, where kalata B1 productivity was in a similar order (3.41 μg per day) due to the higher growth index. O. affinis suspension cultures were shown to accumulate comparable specific kalata B1 concentrations in a delayed growth associated
production pattern. These were dependent on irradiation intensity (0.16 mg g−1 at 2 μmol m−2 s−1; 0.28 mg g−1 at 35 μmol m−2 s−1). The batch cultivation process resulted in a maximum productivity of 27.30 μg per litre and day with culture doubling times
of 1.16 d−1. Submers operation represented a 8-fold product enhancement compared to callus cultivation. 相似文献
16.
Effects of hydrologic and water quality drivers on periphyton dynamics in the southern Everglades 总被引:2,自引:2,他引:0
David M. Iwaniec Daniel L. Childers Damon Rondeau Christopher J. Madden Colin Saunders 《Hydrobiologia》2006,569(1):223-235
Everglades periphyton mats are tightly-coupled autotrophic (algae and cyanobacteria) and heterotrophic (eubacteria, fungi
and microinvertebrates) microbial assemblages. We investigated the effect of water column total phosphorus and nitrogen concentrations,
water depth and hydroperiod on periphyton of net production, respiration, nutrient content, and biomass. Our study sites were
located along four transects that extended southward with freshwater sheetflow through sawgrass-dominated marsh. The water
source for two of the transects were canal-driven and anchored at canal inputs. The two other transects were rain-driven (ombrotrophic)
and began in sawgrass-dominated marsh. Periphyton dynamics were examined for upstream and downstream effects within and across
the four transects. Although all study sites were characterized as short hydroperiod and phosphorus-limited oligotrophic,
they represent gradients of hydrologic regime, water source and water quality of the southern Everglades. Average periphyton
net production of 1.08 mg C AFDW−1 h−1 and periphyton whole system respiration of 0.38 mg C AFDW−1 h−1 rates were net autotrophic. Biomass was generally highest at ombrotrophic sites and sites downstream of canal inputs. Mean
biomass over all our study sites was high, 1517.30 g AFDW m−2. Periphyton was phosphorus-limited. Average periphyton total phosphorus content was 137.15 μg P g−1 and average periphyton total N:P ratio was 192:1. Periphyton N:P was a sensitive indicator of water source. Even at extremely
low mean water total phosphorus concentrations ( ≤ 0.21 μmol l−1), we found canal source effects on periphyton dynamics at sites adjacent to canal inputs, but not downstream of inflows.
These canal source effects were most pronounced at the onset of wet season with initial rewetting. Spatial and temporal variability
in periphyton dynamics could not solely be ascribed to water quality, but was often associated with both hydrology and water
source. 相似文献
17.
The Western Australian termite,Drepanotermes tamminensis (Hill), harvests various plant materials according to biomass availability. The main litter components harvested by this
termite in a woodland dominated byEucalyptus capillosa are bark and leaves of the major tree species, while in shrubland dominated byAllocasuarina campestris, shoots of this species are taken. Harvesting mainly occurs during the autumn (April–May) and spring (September–October)
seasons. The commencement and duration of harvesting appears to depend partly on weather conditions, with harvesting taking
place at temperatures between 15 and 25°C after periods of rain. This species of termite harvests approximately 15.6 g m−2 year−1 and 3.2 g m2 year−1 (dry weight of plant material) in the woodland and shrubland, respectively. 相似文献
18.
Natalia P. Kosykh Natalia G. Koronatova Natalia B. Naumova Argenta A. Titlyanova 《Wetlands Ecology and Management》2008,16(2):139-153
We measured phytomass stock and production in Western Siberian mire ecosystems (palsa, ridge, oligotrophic and mesotrophic
hollows, fen). To determine the contribution of different phytomass fractions into total production, we developed a method
to estimate below-ground production (BNP). Standing crop of living above-ground phytomass on treeless plots varied from 300
to 660 g m−2, reaching maximum on palsa, where 81% of phytomass consisted of Sphagnum mosses and lichens. In the hollows and the fen, Sphagnum percentage varied from 70 to 95%. Standing crop of living below-ground phytomass varied from 325 to 1,210 g m−2. It consisted of woody stems, stem bases, rhizomes and roots, with the latter contributing from 30 to 60%. Total production
of mire ecosystems in northern taiga of Western Siberia ranged from 350 to 960 g m−2 year−1 and depended on microtopography of the ecosystem (the presence of permafrost and water table depth). Production of treeless
plant communities located on the elevated sites depended on the presence of permafrost: in comparison with the ridge, palsa
production was lower. Production on the low sites increased with increase pH and reached maximum (960 g m−2 year−1) in poor fens. Bryophytes were the major producers above ground. Their production varied from 100 to 272 g m−2 year−1 and reached maximum on ridges. BNP contributed 37–66%, increasing due to increased contribution of sedges. 相似文献
19.
The Florida Everglades is a naturally oligotrophic hydroscape that has experienced large changes in ecosystem structure and
function as the result of increased anthropogenic phosphorus (P) loading and hydrologic changes. We present whole-ecosystem
models of P cycling for Everglades wetlands with differing hydrology and P enrichment with the goal of synthesizing existing
information into ecosystem P budgets. Budgets were developed for deeper water oligotrophic wet prairie/slough (‘Slough’),
shallower water oligotrophic Cladium jamaicense (‘Cladium’), partially enriched C. jamaicense/Typha spp. mixture (‘Cladium/Typha’), and enriched Typha spp. (‘Typha’) marshes. The majority of ecosystem P was stored in the soil in all four ecosystem types, with the flocculent
detrital organic matter (floc) layer at the bottom of the water column storing the next largest proportion of ecosystem P
pools. However, most P cycling involved ecosystem components in the water column (periphyton, floc, and consumers) in deeper
water, oligotrophic Slough marsh. Fluxes of P associated with macrophytes were more important in the shallower water, oligotrophic
Cladium marsh. The two oligotrophic ecosystem types had similar total ecosystem P stocks and cycling rates, and low rates
of P cycling associated with soils. Phosphorus flux rates cannot be estimated for ecosystem components residing in the water
column in Cladium/Typha or Typha marshes due to insufficient data. Enrichment caused a large increase in the importance of
macrophytes to P cycling in Everglades wetlands. The flux of P from soil to the water column, via roots to live aboveground
tissues to macrophyte detritus, increased from 0.03 and 0.2 g P m−2 yr−1 in oligotrophic Slough and Cladium marsh, respectively, to 1.1 g P m−2 yr−1 in partially enriched Cladium/Typha, and 1.6 g P m−2 yr−1 in enriched Typha marsh. This macrophyte translocation P flux represents a large source of internal eutrophication to surface
waters in P-enriched areas of the Everglades. 相似文献
20.
Life-history and production of Olinga feredayi in both benthic and hyporheic stream habitats were investigated in a pristine Waikato, New Zealand, forest stream over two
years to investigate the contribution of hyporheic habitat to total secondary production. O. feredayi had a univoltine life-history with adult emergence occurring from November to March. Larvae with case lengths < 2 mm were
present on most dates suggesting delayed egg hatching. Benthic densities were inversely related to maximum peak daily flow
in the month prior to sampling, and positively related to the dry mass of particulate organic matter present in samples. Reach-average
benthic production calculated by the size-frequency method was 0.024 g DM m−2 year−1. Hyporheic production was 4.276 g DM m−3 year−1 and 6.462 g DM m−3 year−1 in colonisation baskets set at 15–30 cm and 30–45 cm within the substratum, respectively, 2.3–3.4 times greater than production
in surface baskets (0–15 cm). Averaged out over the reach scale, it was estimated that 96% of annual secondary production
of O. feredayi occurred in hyporheic habitats >10 cm below the streambed surface. Our study clearly demonstrates that only sampling benthic
habitats can lead to gross under-estimation of population-level annual production, and provides evidence for the role of the
hyporheos as a source of secondary production that may partly account for the Allen Paradox. 相似文献