共查询到20条相似文献,搜索用时 781 毫秒
1.
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
2.
Secondary production and diet of an invasive snail in freshwater wetlands: implications for resource utilization and competition 总被引:1,自引:0,他引:1
Invasive species can monopolize resources and thus dominate ecosystem production. In this study we estimated secondary production
and diet of four populations of Pomacea canaliculata, a freshwater invasive snail, in wetlands (abandoned paddy, oxbow pond, drainage channel, and river meander) in monsoonal
Hong Kong (lat. 22°N). Apple snail secondary production (ash-free dry mass [AFDM]) ranged from 165.9 to 233.3 g m−2 year−1, and varied between seasons. Production was lower during the cool dry northeast monsoon, when water temperatures might have
limited growth, but fast growth and recruitment of multiple cohorts were possible throughout much (7–10 months) of the year
and especially during the warm, wet southwest monsoon. The diet, as revealed by stomach-content analysis, consisted mainly
of detritus and macrophytes, and was broadly consistent among habitats despite considerable variation in the composition and
cover of aquatic plants. Apple snail annual production was >10 times greater than production estimates for other benthic macroinvertebrates
in Hong Kong (range 0.004–15 g AFDM m−2 year−1, n = 29). Furthermore, annual production estimates for three apple snail populations (i.e. >230 g AFDM m−2 year−1) were greater than published estimates for any other freshwater snails (range 0.002–194 g AFDM m−2 year−1, n = 33), regardless of climatic regime or habitat type. High production by P. canaliculata in Hong Kong was attributable to the topical climate (annual mean ~24°C), permitting rapid growth and repeated reproduction,
together with dietary flexibility including an ability to consume a range of macrophytes. If invasive P. canaliculata can monopolize food resources, its high productivity indicates potential for competition with other macroinvertebrate primary
consumers. Manipulative experiments will be needed to quantify these impacts on biodiversity and ecosystem function in wetlands,
combined with management strategies to prevent further range extension by P. canaliculata. 相似文献
3.
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
4.
Karibu Fukuzawa Hideaki Shibata Kentaro Takagi Fuyuki Satoh Takayoshi Koike Kaichiro Sasa 《Ecological Research》2007,22(3):485-495
We measured the vertical distribution and seasonal patterns of fine-root production and mortality using minirhizotrons in
a cool–temperate forest in northern Japan mainly dominated by Mongolian oak (Quercus crispula) and covered with a dense understory of dwarf bamboo (Sasa senanensis). We also investigated the vertical distribution of the fine-root biomass using soil coring. We also measured environmental
factors such as air and soil temperature, soil moisture and leaf area indices (LAI) of trees and the understory Sasa canopy for comparison with the fine-root dynamics. Fine-root biomass to a depth of 60 cm in September 2003 totaled 774 g m−2, of which 71% was accounted for by Sasa and 60% was concentrated in the surface soil layer (0–15 cm), indicating that understory Sasa was an important component of the fine-root biomass in this ecosystem. Fine-root production increased in late summer (August)
when soil temperatures were high, suggesting that temperature partially controls the seasonality of fine-root production.
In addition, monthly fine-root production was significantly related to Sasa LAI (P<0.001), suggesting that fine-root production was also affected by the specific phenology of Sasa. Fine-root mortality was relatively constant throughout the year. Fine-root production, mortality, and turnover rates were
highest in the surface soil (0–15 cm) and decreased with increasing soil depth. Turnover rates of production and mortality
in the surface soil were 1.7 year−1 and 1.1 year−1, respectively. 相似文献
5.
A reciprocal transplant experiment (RTE) of the reef-building coral Porites lobata between shallow (1.5 m at low tide) back reef and forereef habitats on Ofu and Olosega Islands, American Samoa, resulted
in phenotypic plasticity for skeletal characteristics. Transplants from each source population (back reef and forereef) had
higher skeletal growth rates, lower bulk densities, and higher calcification rates on the back reef than on the forereef.
Mean annual skeletal extension rates, mean bulk densities, and mean annual calcification rates of RTE groups were 2.6–9.8 mm year−1, 1.41–1.44 g cm−3, and 0.37–1.39 g cm−2 year−1 on the back reef, and 1.2–4.2 mm year−1, 1.49–1.53 g cm−3, and 0.19–0.63 g cm−2 year−1 on the forereef, respectively. Bulk densities were especially responsive to habitat type, with densities of transplants increasing
on the high energy forereef, and decreasing on the low energy back reef. Skeletal growth and calcification rates were also
influenced by source population, even though zooxanthella genotype of source colonies did not vary between sites, and there
was a transplant site x source population interaction for upward linear extension. Genetic differentiation may explain the
source population effects, or the experiment may have been too brief for phenotypic plasticity of all skeletal characteristics
to be fully expressed. Phenotypic plasticity for skeletal characteristics likely enables P. lobata colonies to assume the most suitable shape and density for a wide range of coral reef habitats. 相似文献
6.
Sharon M. L. Ewe Evelyn E. Gaiser Daniel L. Childers David Iwaniec Victor H. Rivera-Monroy Robert R. Twilley 《Hydrobiologia》2006,569(1):459-474
We present here a 4-year dataset (2001–2004) on the spatial and temporal patterns of aboveground net primary production (ANPP)
by dominant primary producers (sawgrass, periphyton, mangroves, and seagrasses) along two transects in the oligotrophic Florida
Everglades coastal landscape. The 17 sites of the Florida Coastal Everglades Long Term Ecological Research (FCE LTER) program
are located along fresh-estuarine gradients in Shark River Slough (SRS) and Taylor River/C-111/Florida Bay (TS/Ph) basins
that drain the western and southern Everglades, respectively. Within the SRS basin, sawgrass and periphyton ANPP did not differ
significantly among sites but mangrove ANPP was highest at the site nearest the Gulf of Mexico. In the southern Everglades
transect, there was a productivity peak in sawgrass and periphyton at the upper estuarine ecotone within Taylor River but
no trends were observed in the C-111 Basin for either primary producer. Over the 4 years, average sawgrass ANPP in both basins
ranged from 255 to 606 g m−2 year−1. Average periphyton productivity at SRS and TS/Ph was 17–68 g C m−2 year−1 and 342–10371 g C m−2 year−1, respectively. Mangrove productivity ranged from 340 g m−2 year−1 at Taylor River to 2208 g m−2 year−1 at the lower estuarine Shark River site. Average Thalassia testudinum productivity ranged from 91 to 396 g m−2 year−1 and was 4-fold greater at the site nearest the Gulf of Mexico than in eastern Florida Bay. There were no differences in periphyton
productivity at Florida Bay. Interannual comparisons revealed no significant differences within each primary producer at either
SRS or TS/Ph with the exception of sawgrass at SRS and the C−111 Basin. Future research will address difficulties in assessing
and comparing ANPP of different primary producers along gradients as well as the significance of belowground production to
the total productivity of this ecosystem. 相似文献
7.
Primary production of phytoplankton and secondary production of a daphnid and a chaoborid were studied in a small eutrophic
pond. The gross primary production of phytoplankton was 290 gC m−2 per 9 months during April–December. Regression analysis showed that the gross primary production was related to the incident
solar radiation and the chlorophylla concentration and not to either total phosphorus or total inorganic nitrogen concentration. The mean chlorophylla concentration (14.2 mg m−3), however, was about half the expected value upon phosphorus loading of this pond. The mean zooplankton biomass was 1.60
g dry weight m−2, of whichDaphnia rosea and cyclopoid copepods amounted to 0.69 g dry weight m−2 and 0.61 g dry weight m−2, respectively. The production ofD. rosea was high during May–July and October and the level for the whole 9 months was 22.6 g dry weight m−2.Chaoborus flavicans produced 10 complete and one incomplete cohorts per year. Two consecutive cohorts overlapped during the growing season. The
maximum density, the mean biomass, and the production were 19,100 m−2, 0.81 g dry weight m−2, and 11.7 g dry weight m−2yr−1, respectively. As no fish was present in this pond, the emerging biomass amounted to 69% of larval production. The production
ofC. flavicans larvae was high in comparison with zooplankton production during August–September, when the larvae possibly fed not only
on zooplankton but also algae. 相似文献
8.
North American beavers (Castor canadensis) were introduced to Tierra del Fuego Island in 1946 for their fur, and have since spread across the archipelago and onto
the South American mainland. We assessed the impact of invasive beavers on streams of these forested watersheds by quantifying
the trophic basis of production (TBP) and consumptive organic matter flows of benthic macroinvertebrate assemblages. TBP was
determined in two streams: clear- and black-water. Stable isotopes were used across four streams to further elucidate food
web structure and dominant pathways. TBP and stable isotopes showed that terrestrially derived organic matter (amorphous detritus,
leaves, and wood) supported a majority of secondary production in the benthic food webs at all sites (forested reaches, beaver
ponds, and sections downstream of ponds with foraged riparian zones). The magnitude of these flows was enhanced in beaver-modified
sites compared with forested habitats (4.0–5.3× increase g AFDM m−2 year−1 in pond habitats, 1.1–2.1× increase in downstream habitats). Diatoms were the only autochthonous resource identified in macroinvertebrate
guts, but their contribution to secondary production was small. Consumptive flows mirrored trends in TBP (i.e., dominance
of terrestrial sources and greater magnitude in beaver ponds). Collector–gatherer consumption of amorphous detrital material
dominated food web flows in all habitats, but was higher in beaver ponds relative to other habitats. Food web structure was
simplified in beaver ponds; only two of the five possible functional groups contributed >1% of total organic matter flow in
ponds (collector–gatherers and predators). Consumptive flows to predators increased in ponds, and stable isotopes of nitrogen
and carbon (δ15N and δ13C) corroborated a relatively greater importance of predators (greater trophic distance), as well as less diversity of basal
resources (less variation in δ13C) in ponds. Our findings indicate that invasive beaver’s engineering activities resulted in greater flows of terrestrial
organic matter subsidies to in-stream food webs, which had a relatively greater change in the clear-water than in the black-water
stream. Owing to the fact that these streams were naturally dependent on allochthonous resources for a majority of production
and material flows, changes wrought by beavers to streams in forested environments are probably less than in watersheds with
inherently greater dependence on autochthonous production such as the adjacent steppe biome. 相似文献
9.
This investigation represents the first integrated study of primary production, nutrient dynamics and mineralisation in a
northeastern fjord of Greenland. The data presented represent conditions and activities during the early summer thaw (first
2 weeks of July). Primary production (5.3 mmol C m−2 d−2) and chlorophylla (4.1 μg 1−1) values were found to be comparable with measurements from other Arctic regions. Water column N-fixation rates were low (<0.02
μmol N m−1 d−1), but comparable with other estuarine systems. Despite a constant low temperature in the bottom waters (-1.0 to -1.8°C),
a high sedimentary O2 uptake (740 μmol m−2 h−2) was observed and was primarily caused by the presence of benthic infauna. Bioturbation by benthic infauna was reflected
in both homogeneous210Pb and137Cs profiles in the upper 4 cm of the sediment. Permanent accumulation within Young Sound was measured to 0.12 cm/year corresponding
to 153 mmol C m−2 year−1 and 15 mmol N m−2 year−1. Rates of nitrification (22 μmol m−2 h−1) and denitrification (9 μmol m−2 h−1) were comparable with rates reported for other sediments with much higher environmental temperatures. Suphate reduction rates
integrated over the upper 12 cm of the sediment were calculated to be 44 μmol m−2h−1. 相似文献
10.
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
11.
Pierre Marmonier Christophe Piscart Pierre Emmanuel Sarriquet Didier Azam Eric Chauvet 《Hydrobiologia》2010,641(1):203-214
Particulate organic matter is the major source of energy for most low-order streams, but a large part of this litter is buried
within bed sediment during floods and thus become poorly available for benthic food webs. The fate of this buried litter is
little studied. In most cases, measures of breakdown rates consist of burying a known mass of litter within the stream sediment
and following its breakdown over time. We tested this method using large litter bags (15 × 15 cm) and two field experiments.
First, we used litter large bags filled with Alnus glutinosa leaves (buried at 20 cm depth with a shovel) in six stations within different land-use contexts and with different sediment
grain sizes. Breakdown rates were surprisingly high (0.0011–0.0188 day−1) and neither correlate with most of the physico-chemical characteristics measured in the interstitial habitats nor with the
land-use around the stream. In contrast, the rates were negatively correlated with a decrease in oxygen concentrations between
surface and buried bags and positively correlated with both the percentage of coarse particles (20–40 mm) in the sediment
and benthic macro-invertebrate richness. These results suggest that the vertical exchanges with surface water in the hyporheic
zone play a crucial role in litter breakdown. Second, an experimental modification of local sediment (removing fine particles
with a shovel to increase vertical exchanges) highlighted the influence of grain size on water and oxygen exchanges, but had
no effect on hyporheic breakdown rates. Burying large litter bags within sediments may thus not be a relevant method, especially
in clogged conditions, due to changes induced through the burial process in the vertical connectivity between surface and
interstitial habitats that modify organic matter processing. 相似文献
12.
Checo Colón-Gaud Scot Peterson Matt R. Whiles Susan S. Kilham Karen R. Lips Cathy M. Pringle 《Hydrobiologia》2008,603(1):301-312
Allochthonous inputs of detritus represent an important energy source for streams in forested regions, but dynamics of these
materials are not well studied in neotropical headwater streams. As part of the tropical amphibian declines in streams (TADS)
project, we quantified benthic organic matter standing stocks and organic seston dynamics in four Panamanian headwater streams,
two with (pre-amphibian decline) and two without (post-decline) healthy amphibian assemblages. We also measured direct litterfall
and lateral litter inputs in two of these streams. Continuous litterfall and monthly benthic samples were collected for 1 year,
and seston was collected 1–3 times/month for 1 year at or near baseflow. Direct litterfall was similar between the two streams
examined, ranging from 934–1,137 g DM m−2 y−1. Lateral inputs were lower, ranging from 140–187 g DM m−1 y−1. Dead leaves (57–60%), wood (24–29%), and green leaves (8–9%) contributed most to inputs, and total inputs were generally
higher during the rainy season. Annual habitat-weighted benthic organic matter standing stocks ranged from 101–171 g AFDM
m−2 across the four study reaches, with ∼4 × higher values in pools compared to erosional habitats. Total benthic organic matter
(BOM) values did not change appreciably with season, but coarse particulate organic matter (CPOM, >1 mm) generally decreased
and very fine particulate organic matter (VFPOM, 1.6–250 μm) generally increased during the dry season. Average annual seston
concentrations ranged from 0.2–0.6 mg AFDM l−1 (fine seston, <754 μm >250 μm) and 2.0–4.7 mg AFDM l−1 (very fine, <250 μm >1.6 μm), with very fine particles composing 85–92% of total seston. Quality of fine seston particles
in the two reaches where tadpoles were present was significantly higher (lower C/N) than the two where tadpoles had been severely
reduced (P = 0.0028), suggesting that ongoing amphibian declines in this region are negatively influencing the quality of particles
exported from headwaters. Compared to forested streams in other regions, these systems receive relatively high amounts of
allochthonous litter inputs but have low in-stream storage.
Handling editor: J. Padisak 相似文献
13.
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
14.
Wyatt F. Cross Emma J. Rosi-Marshall Kathrine E. Behn Theodore A. Kennedy Robert O. HallJr. A. Elizabeth Fuller Colden V. Baxter 《Biological invasions》2010,12(9):3033-3043
Species invasions are often associated with large-scale human alteration of ecosystems. One classic example is the increasing
dominance of non-native taxa below and above dams on large rivers. These dams substantially alter the physical template of
river ecosystems, and exotic taxa often proliferate with potentially large impacts on coexisting taxa and ecosystem processes.
Here we document the invasion of New Zealand mud snails (Potamopyrgus antipodarum) in the Colorado River directly below Lake Powell in Glen Canyon, Arizona, USA. We also quantified the magnitude and variability
in growth and secondary production of P. antipodarum during 2006–2007 to gain a functional measure of their role in the ecosystem. Snails were first detected in Glen Canyon in
1995, and have since become a dominant component of the invertebrate fauna. Throughout the invasion of P. antipodarum, biomass of other dominant taxa was variable and did not appear to be positively or negatively influenced by the presence
of P. antipodarum. Specific growth rates of P. antipodarum were moderate (0.001–0.030 day−1) and strongly related to body size. Mean annual habitat-weighted biomass and production were relatively high (biomass: 4.4 g/m2; secondary production: 13.3 g m−2 year−1) and similar among habitats. Mean monthly biomass and daily secondary production were much more variable, with highest values
occurring in autumn. We show that invasion of a productive aquatic consumer to a highly disturbed river ecosystem had little
detectable influence on the biomass of other invertebrate taxa. However, additional research will be necessary to fully understand
and predict effects of P. antipodarum on coexisting taxa. 相似文献
15.
Hidenobu Kunii 《Ecological Research》1988,3(3):305-318
In order to determine the seasonal growth and biomass ofTrapa japonica Flerov, field observations were carried out at Ojaga-ike Pond, Chiba, Japan, during 1979 and 1980. In spring, the plant showed
exponential growth (c. 0.080 g g−1 day−1) and shoot elongation was as rapid as 10 cm day−1. The plant attained its maximum biomass (380.5±35.1 g m−2) in late August, and about 50% of this was concentrated in the topmost 30-cm stratum (645.7±33.1 g m−3); maximum total stem length exceeded 6m. The plant produced large (500–800 mg per fruit), but small numbers of nut-like fruit
(maximum, 5 fruits per rosette). Defoliation occurred almost linearly with time at a rate of 30.6 leaves m−2 day−1; annual net leaf production was estimated to be about twice as large as the seasonal maximum leaf biomass. While the number
of leaves per rosette showed moderate seasonal change, rosette density, rosette area and leaf dry weight changed considerably
during the year. From the negative log-log correlation between mean total leaf dry weight per rosette and rosette density,
density-dependent rosette growth was assumed. The cause of the wide spread of this species in aquatic habitats is briefly
discussed in terms of its seed size and morphology. 相似文献
16.
Hiroshi Koizumi 《Journal of plant research》1989,102(4):521-532
Photosynthetic and respiratory activities and gross production in relation to temperature conditions were investigated in
the population of an evergreen herb,Pyrola japonica, growing on the floor of a deciduous forest in the warm temperate region of central Japan.
Analysis of the temperature-photosynthesis relationship ofP. japonica leaves during the growing season indicated distinct seasonal changes in the temperature optimum for photosynthesis. This
population was found to be acclimatable to ambient air temperatures exceeding 15C, but this acclimation became less pronounced
under thermal conditions below 15 C. This plant possessed narrow photosynthetic optima in the warm season but wide optima
in the cold season. The shape of the temperature-respiration curve did not vary significantly with the months except for April.
The Q10 for respiration between 10 C and 20 C was calculated to be 1.93–2.65. Annual dry matter loss associated with respiration
was estimated to amount to 159.1 g d.w.m−2 based on the measurements of the seasonal changes in the respiratory activity of each organ. Gross production of this population
was estimated to be 219.3 g d.w.m−2 year−1 as the sum total of the net production (60.2 g d.w.m−2year−1) and the respiration. Monthly gross production was high in the early growing season, and low and stable in winter. 相似文献
17.
The role of seed bank, seed rain, and regeneration from seedlings and sprouts after swidden agriculture was compared in 5-,
10- and 20-year-old secondary forest and in a primary forest in Bragantina, Pará, Brazil. The seed bank (0–5 cm soil depth)
was largest in the 5-year-old forest (1190 ± 284 seeds m−2) and decreased nearly ten-fold with age to 137 ± 19 seeds m−2 in the primary forest. The highest seed rain was in the 5-year-old forest (883 ± 230 seeds m−2 year−1) and the least in the primary forest (220 ± 80 seeds m−2 year−1). Large plants (≥5 cm dbh) had more individuals and species that regenerated from sprouts than from seeds and the most abundant
tree species in the secondary forest stands of all ages appear to be maintained by sprouting. The smaller individuals (≥1 m
tall, <5 cm dbh) in the 5-year-old forest were mainly from sprouts, but those in the older secondary forests originated mainly
from seeds. These results show that at the beginning of succession, although many species can be introduced to swidden fallow
from seed bank and seed rain, it is the sprout that is the main source of recruits of primary forest species in secondary
forests in Bragantina. 相似文献
18.
Tarek Daas Mourad Younsi Ouided Daas-Maamcha Patrick Gillet Patrick Scaps 《Helgoland Marine Research》2011,65(2):165-173
The polychaete Nereis falsa Quatrefages, 1866 is present in the area of El Kala National Park on the East coast of Algeria. Field investigations were
carried out from January to December 2007 to characterize the populations’ reproductive cycle, secondary production and dynamics.
Reproduction followed the atokous type, and spawning occured from mid-June to the end of August/early September when sea temperature
was highest (20–23°C). The diameter of mature oocytes was approximately 180 μm. Mean lifespan was estimated to about one year.
In 2007, the mean density was 11.27 ind. m−2 with a minimum of 7.83 ind. m−2 in April and a maximum of 14.5 ind. m−2 in February. The mean annual biomass was 1.36 g m−2 (fresh weight) with a minimum of 0.86 g m−2 in December and a maximum of 2.00 g m−2 in June. The population consisted of two cohorts distinguishable from size frequency distributions. One cohort corresponded
to the recruitment of 2006 and the other appeared during the study period in September 2007. The annual production of N. falsa was 1.45 g m−2 year−1, and the production/biomass ratio was 1.07 year−1. 相似文献
19.
Synchrony, one of the main traits of population life histories, refers to the degree to which individuals complete a certain
stage of the life cycle at the same time. It can be governed by temperature, variations in temperature, photoperiodic cues,
detritus inputs, or discharge regimes. We investigated life cycles and secondary production of five caddisfly species in a
second order stream in the Patagonian Mountains. In addition, we analyzed what environmental variables were implied in the
caddisfly assemblage variation. Mastigoptila sp. (Glossosomatidae) and Eosericostoma aequispina (Helicophidae), Myotrichia murina (Sericostomatidae), Brachysetodes quadrifidus (Leptoceridae), and Neoatopsyche brevispina (Hydrobiosidae) showed univoltine life cycles, with an extended recruitment with no overlapping cohorts and a relatively
well-synchronized imaginal emergence taking place during spring summer seasons. However, Myotrichia murina (Sericostomatidae) displayed a complex life cycle with mixed populations taking 10–12 months to develop, and pupae being
collected almost continuously. The annual secondary production per species varied from 11.06 (E. aequispina) to 310.5 mg m−2 year−1 (M. murina), being overall caddisfly production (0.5 g m−2 year−1) similar to that reported for cold springs in other regions. The highest growth rates (K) were observed during late winter and spring (mostly September) and ranged from 0.70 to 3.70% day−1 in M. longicornuta and N. brevispina, respectively. Redundancy analysis indicated that seasonally dynamic variables, water temperature, discharge, and detritus
biomass were the main predictors of caddisfly assemblage variation; consequently at this cold stream (mean annual 5.9°C),
with a regular availability of food supply, these parameters ruled Trichoptera life histories and secondary production. As
documented for other mountainous temperate areas, synchrony would be a dominant trait on life histories of Trichoptera species
inhabiting Patagonian streams. 相似文献
20.
The goal of this research was to determine the role of Lepidostoma hirtum Fabricius 1775 in the fragmentation of allochtonous organic material, in a segment of a mountain river in central Portugal.
For this purpose, we measured leaf fragmentation and growth rates at four temperatures (9, 12, 15 and 18 °C) and four leaf
types (alder, Alnus glutinosa L.; oak, Quercus andegavensis Hy; poplar, Populus × canadensis Moench; and chestnut, Castanea sativa Mill.). Growth rates ranged from 0.012 to 0.049 mg AFDW day−1 with no significant effect of temperature and leaf type. Fragmentation/consumption rates were significantly higher for alder
(1.62 mg animal−1 day−1) than for other leaf types, and significantly lower at 9 °C (0.70 mg animal−1 day−1) than at any other temperature (1.12 mg animal−1 day−1). In the studied stream, L. hirtum larvae had a univoltine life history, with an asynchronous development. Secondary production of L. hirtum ranged from 53.95 mg m−2 year−1 (pools) to 63.12 mg m−2 year−1 (riffles). Annual P/B ratios differ between habitats: they were 4.01 year−1 for pools and 4.49 year−1 for riffles. Considering the average density of this species in the study river and their consumption rates, this species
has the potential to fragment 8.6 times the mean annual standing stock of organic matter, in the study location. 相似文献