Litterfall Data Research Articles

Nation‐wide litter fall data from 21 forests of the Monitoring Sites 1000 Project in Japan

AbstractThis data paper reports litter fall data collected in a network of 21 forest sites in Japan. This is the largest litter fall data set freely available in Japan to date. The network is a part of the Monitoring Sites 1000 Project launched by the Ministry of the Environment, Japan. It covers subarctic to subtropical climate zones and the four major forest types in Japan. Twenty‐three permanent plots in which usually 25 litter traps were installed were established in old‐growth or secondary natural forests. Litter falls were collected monthly from 2004, and sorted into leaves, branches, reproductive structures and miscellaneous. The data provide seasonal patterns and inter‐annual dynamics of litter falls, and their geographical patterns, and offer good opportunities for meta‐analyses and comparative studies among forests.

Litterfall and nutrient return in five tree species in a common garden experiment

Canopy litterfall is a significant pathway for return of nutrients and carbon (C) to the soil in forest ecosystems. Litterfall was studied in five even-aged stands of Norway spruce, Sitka spruce, Douglas-fir, European beech and common oak at three different locations in Denmark; two sandy sites, Ulborg and Lindet in Jutland, and one loamy site, Frederiksborg on Zealand. Litterfall was collected during three years from 1994 to 1996 in all five species and during six years from 1994 to 1999 in Norway spruce, Sitka spruce and European beech. The average total litterfall was in the range of 3200–3700 kg ha −1 yr −1 and did not differ significantly among tree species. There were no significant differences in total litterfall among sites during the short period, but during the longer period the richer site Frederiksborg had significantly higher total and foliar litterfall amounts compared to the more nutrient-poor sites Lindet and Ulborg. There were close relationships between foliar and total litterfall suggesting that foliar litterfall can be reliably estimated from total litterfall. Beech and oak bud scale litter was significantly related to foliar litterfall. The amount of branch and twig litter was significantly higher in oak than in other tree species. The average foliar litterfall was well related to the annual volume increment. The relationship differed markedly from previously reported relationships based on global litterfall data suggesting that such relationships are better evaluated at the regional level. Nutrient concentrations and fluxes in foliar litterfall were not significantly different among the five tree species. However, there was a significant effect of site on most nutrient concentrations of the three litterfall fractions, and foliar fluxes of P, Ca and Mn were all significantly highest at Frederiksborg and lowest at Ulborg. The similarity in litterfall inputs to the forest floor under these five tree species suggested that previous reports of large variability in forest floor accumulation should primarily be attributed to differences in litter decomposition.

Nitrogen and Phosphorus Release from Mixed Litter Layers is Lower than Predicted from Single Species Decay

Ecosystem-level nutrient dynamics during decomposition are often estimated from litter monocultures. If species effects are additive, we can statistically predict nutrient dynamics in multi-species systems from monoculture work, and potential consequences of species loss. However, if species effects are dependent on interactions with other litter species (that is, non-additive), predictions based on monoculture data will likely be inaccurate. We conducted a 3-year, full-factorial, mixed-litter decomposition study of four dominant tree species in a temperate forest and measured nitrogen and phosphorus dynamics to explore whether nutrient dynamics in mixtures were additive or non-additive. Following common approaches, we used litterfall data to predict nutrient dynamics at the ecosystem-level. In mixtures, we observed non-additive effects of litter mixing on nutrient dynamics: the presence of nutrient-rich species in mixture facilitated nutrient release, whereas nutrient-poor species facilitated nutrient retention. Fewer nutrients were released from mixtures containing high-quality litter, and more immobilized from mixtures containing low-quality litter, than predicted from monocultures, creating a difference in overall nutrient release between predicted and actual dynamics in litter mixtures. Nutrient release at the ecosystem-level was greatly overestimated when based on monocultures because the effect of species interactions on nutrient immobilization was not accounted for. Our data illustrate that the identity of species in mixtures is key to their role in non-additive interactions, with repercussions for mineral nutrient availability and storage. These results suggest that predictions of ecosystem-level nutrient dynamics using litter monoculture data likely do not accurately represent actual dynamics because the effects of litter species interactions are not incorporated.

Observation and modeling of NPP for Pinus elliottii plantation in subtropical China

Based on the stem analysis of 59 individuals of Pinus elliottii in combination with tree biomass models, we calculated annual biomass increment of forest plots at Qianyanzhou Ecological Station, Chinese Academy of Sciences in subtropical China. In addition, canopy layer and community NPP were calculated based on 12 years’ litter fall data. NPP of the 21-year-old forest was estimated by using the BIOME BGC model; and both measured NPP and estimated NPP were compared with flux data. Community biomass was 10574 g · m−2; its distribution patterns in tree layer, shrub layer, herbaceous layer, tree root, herbaceous and shrub roots and fine roots were 7542, 480, 239, 1810, 230, 274 and 239 g · m−2, respectively. From 1999 to 2004, the average annual growth rate and litter fall were 741 g · m−2 · a−1 (381.31 gC · m−2 · a−1) and 849 g · m−2 · a−1 (463 gC · m−2 · a−1), respectively. There was a significant correlation between annual litter fall and annual biomass increment; and the litter fall was 1.19 times the biomass increment of living trees. From 1985 to 2005, average NPP and GPP values based on BGC modeling were 630.88 (343.31–906.42 gC · m−2 · a−1) and 1 800 gC · m−2 · a−1 (1351.62–2318.26 gC · m−2 · a−1). Regression analysis showed a linear relationship (R 2=0.48) between the measured and simulated tree layer NPP values. NPP accounted for 30.2% (25.6%–32.9%) of GPP, while NEP accounted for 57.5% (48.1%–66.5%) of tree-layer NPP and 41.74% (37%–52%) of stand NPP. Soil respiration accounted for 77.0% of measured tree NPP and 55.9% of the measured stand NPP. NEE based on eddy covariance method was 12.97% higher than the observed NEP.

Effects of elevated atmospheric CO2 and tropospheric O3 on nutrient dynamics: decomposition of leaf litter in trembling aspen and paper birch communities

Atmospheric changes could strongly influence how terrestrial ecosystems function by altering nutrient cycling. We examined how the dynamics of nutrient release from leaf litter responded to two important atmospheric changes: rising atmospheric CO2 and tropospheric O3. We evaluated the independent and combined effects of these gases on foliar litter nutrient dynamics in aspen (Populus tremuloides Michx) and birch (Betula papyrifera Marsh)/aspen communities at the Aspen FACE Project in Rhinelander, WI. Naturally senesced leaf litter was incubated in litter bags in the field for 735 days. Decomposing litter was sampled six times during incubation and was analyzed for carbon, and both macro (N, P, K, S, Ca, and Mg) and micro (Mn, B, Zn and Cu) nutrient concentrations. Elevated CO2 significantly decreased the initial litter concentrations of N (−10.7%) and B (−14.4%), and increased the concentrations of K (+23.7%) and P (+19.7%), with no change in the other elements. Elevated O3 significantly decreased the initial litter concentrations of P (−11.2%), S (−8.1%), Ca (−12.1%), and Zn (−19.5%), with no change in the other elements. Pairing concentration data with litterfall data, we estimated that elevated CO2 significantly increased the fluxes to soil of all nutrients: N (+12.5%), P (+61.0%), K (+67.1%), S (+28.0%), and Mg (+40.7%), Ca (+44.0%), Cu (+38.9%), Mn (+62.8%), and Zn (+33.1%). Elevated O3 had the opposite effect: N (−22.4%), P (−25.4%), K (−27.2%), S (−23.6%), Ca (−27.6%), Mg (−21.7%), B (−16.2%), Cu (−20.8%), and Zn (−31.6%). The relative release rates of the nine elements during the incubation was: K ≥ P ≥ mass ≥ Mg ≥ B ≥ Ca ≥ S ≥ N ≥ Mn ≥ Cu ≥ Zn. Atmospheric changes had little effect on nutrient release rates, except for decreasing Ca and B release under elevated CO2 and decreasing N and Ca release under elevated O3. We conclude that elevated CO2 and elevated O3 will alter nutrient cycling more through effects on litter production, rather than litter nutrient concentrations or release rates.

Modelling of planted legume fallows in Western Kenya using WaNuLCAS. (I) Model calibration and validation

Poor soil fertility is the biggest obstacle to agricultural productivity in Sub-Saharan Africa. Improved fallows can help to raise agricultural productivity in these systems of low financial capital, however, experimental testing of their potential application domain and design is costly and time consuming. Models can evaluate alternative systems relatively quickly and at relatively low cost, but must first be validated to assess satisfactory simulation of the target systems. Specific climatic, edaphic, crop and fallow growth data was used from five sites in Western Kenya to calibrate and validate simulations of maize and improved fallow growth using the Water, Nutrient and Light Capture in Agroforestry Systems (WaNuLCAS) model. The model predicted continuous maize yields across the sites with an R 2 of 0.72, an EF (model efficiency) of 0.66 and a CD (coefficient of determination) of 2.73, although the default pedotransfer functions (PTF) for volumetric soil water content used in the model had to be substituted for a tropical soils specific PTF before this was achieved. Predicted maize yield was consistently related to fallow biomass (i.e. higher fallow biomass correlated with higher subsequent maize yields) at two sites and the model predicted maize yields following fallow growth from this subset of the data with an R 2 of 0.42. This relationship of fallow biomass to subsequent maize yield was not observed across the whole data set due to incomplete fallow litterfall data, factors not included in the model and associated poor model prediction of recycled tree biomass. After site and tree calibration, the model can thus be applied to assess fallow management strategies for sites limited by water and nitrogen.

MODELING LEAF DISPERSAL IN MIXED HARDWOOD FORESTS USING A BALLISTIC APPROACH

In mixed-species stands, modeling leaf litter dispersal is important to predict the physical and chemical characteristics of the forest floor, which plays a major role in nutrient cycling and in plant population dynamics. In this study, a spatially explicit model of leaf litterfall was developed and compared with two other models. These three models were calibrated for a mixed forest of oak and beech using litterfall data from mapped forest plots. All models assumed that an allometric equation described individual leaf litter production, but they strongly differed in the modeling of the probability density of leaf shedding with distance from source trees. Two models used a negative exponential function to account for leaf dispersal with distance, and this function was allowed to vary according to wind direction in one of them. In contrast, our approach was based on a simple ballistic equation considering release height, wind speed, wind direction, and leaf fall velocity; the distributions of wind speeds and wind directions were modeled according to a Weibull and a Von Mises distribution, respectively. Using an independent validation data set, all three models provided predictions well correlated to measurements (r > 0.83); however, the two models with a direction-dependent component were slightly more accurate. In addition, parameter estimates of the ballistic model were in close agreement with a foliar litter production equation derived from the literature for beech and with wind characteristics measured during leaf litterfall for both species. Because of its mechanistic background, such a spatially explicit model might be incorporated as a litterfall module in larger models (nutrient cycling, plant population dynamics) or used to determine the manner in which patch size in mixed-species stands influences litter mixture.

Temporal and structural effects of stands on litter production in Melaleuca quinquenervia dominated wetlands of south Florida

Melaleuca quinquenervia dominates large areas of the Florida Everglades in the southeastern USA where it has transformed sedge-dominated marshes into melaleuca forests. Despite its prevalence, very little is known about the ecology and stand dynamics of this invasive tree. We delineated large-, intermediate-, and small-tree stands in non-flooded, seasonally flooded and permanently flooded areas of Florida in 1997, measured their biological attributes, and then quantified litterfall components for 3–4 year periods. Melaleuca wood components and mature seed-capsules comprised the largest and the smallest portions of aboveground biomass, respectively, while leaves, fine stems, mature fruits, bud scales, floral structures, and residues represented decreasingly smaller fractions of the litter during the succeeding year. Dry weight proportion of leaves in litter was greatest (80.9%) in non-flooded and least (69.1%) in permanently flooded habitats. It was also greatest in small (85.6%) and least in large (64.7%) tree stands. Reproductive structures and mature-fruit fractions in litter were highest in large-tree stands whereas the bud-scale fraction showed no relationship to tree size. Seasonally flooded habitats had the most litterfall, wherein small-, intermediate-, and large-tree stands generated 0.662, 0.882, and 1.128 kg m 2 yr 1 , respectively. Dry weight of stems, leaves, bud–scales, floral structures, and mature fruit fractions in litter increased as the predominant size of the trees in the stand increased. Total annual litter production was highest during 1999–2000. Leaf fall occurred year-round with maximal amount during April, July, and October. Highest amounts of bud scales and floral structures fell during October–January, which corresponded with flushes of vegetative growth and major flowering events. Overall, melaleuca alone accounted for nearly 99% of the total litterfall dry weight in all habitats and months sampled. The amount of non-melaleuca litter was greater in small-tree stands than in intermediate- or large-tree stands. Litterfall data of this nature will be helpful in detecting changes occurring in melaleuca canopies in response to biological control impact and in prescribing site-specific management strategies.

Estructura y dinámica del manglar del delta del río Ranchería, Caribe colombiano

We registered seedling survival and biomass increase for Rhizophora mangle L., Avicennia germinans L. and Laguncularia racemosa (L.) Gaertn. f, main mangrove species in the Rancheria River delta, Colombia. Only seedlings of R. mangle were found to survive. We also measured maximum rate of litterfall. We estimated annual litterfall through interpolation within an exponential regression performed with maximum and annual litterfall data published in other sources; the value of annual litterfall for the area was estimated to be 12.9 mgha(-1)y(-1). We found a 7.4 mgha(-1)y(-1)(-1) increase in biomass. Litterfall constitutes the larger fraction of the 20.2 mgha(-1)y(-1) productivity of this mangrove. We believe this is a very high value for a forest under unfavorable natural and human conditions, such as high seasonality and continuous use of the forest to feed goats and sheep. We consider that the high productivity is a response to both natural and anthropogenic stress.

Nutrient-use efficiency in arid-zone forests of the mangroves Rhizophora stylosa and Avicennia marina

Nutrient-use efficiency (NUE) within forests of the mangroves Rhizophora stylosa and Avicennia marina was estimated in arid Western Australia using litter fall rates and rates of leaf CO 2 exchange. Litter fall rates ranged from 9.8 to 34.4 t DW ha −1 y −1 but equated to only 13–41% (mean = 30%) of net canopy primary production. Foliar N:P ratios were in most instances ≥16, suggesting P limitation. NUE for N based on litter fall rates were significantly less (NUE L = 167–322 g DW g −1 N) than those based on photosynthesis measurements (NUE P = 234–448 g DW g −1 N), suggesting that NUE estimates for nitrogen based on litter fall data are underestimates. NUE P estimates for N were significantly greater for R. stylosa than for A. marina. NUE for P were not significantly different, with NUE L ranging from 2905 to 5053 g DW g −1 P and NUE P ranging from 1632 to 4992 g DW g −1 P. Both sets of NUE are at the higher end of the range of estimates calculated for most other forests and equivalent to those for wet tropical mangroves. These arid-zone trees live in low-nutrient habitats, but it appears that selection on components of NUE (i.e. traits that reduce nutrient loss) rather than on NUE itself equates to a lack of clear patterns in NUE between different environments, emphasizing the flexible nature of nutrient allocation in woody plants. NUE in R. stylosa correlated inversely with mature leaf N and P content, implying that NUE in this species is maximized by the synthesis of low-nutrient leaves, i.e. a nutrient retention strategy, whereas such does not appear to be the case for A. marina. This strategy translates into a direct advantage in terms of net primary productivity for R. stylosa. This idea is supported by evidence of longer nutrient residence times for R. stylosa than for A. marina.

Predicting the Spatial Distribution of Leaf Litterfall in a Mixed Deciduous Forest

Abstract An accurate prediction of the spatial distribution of litterfall can improve insight in the interaction between the canopy layer and forest floor characteristics, which is a key feature in forest nutrient cycling. Attempts to model the spatial variability of litterfall have been made across forest types, but the reported models have not yet been compared. We predicted the spatial distribution of leaf litterfall for the same mixed hardwood stand using inverse distance interpolation, ordinary kriging, single and multiple regressions based on plot basal area, and three individual-tree models. Models were calibrated using litterfall data (n = 67) of white birch (Betula pendula Roth), pedunculate oak (Quercus robur L.), and northern red oak (Quercus rubra L.). Model performance was compared using an independent validation data set (n = 37). Interpolation techniques did not reliably estimate spatial patterns of leaf litterfall (r < 0.60, n = 37). However, models incorporating tree data, such as linear regressions and individual-tree models, successfully reproduced the observed spatial litterfall heterogeneity of each species (r > 0.80). No model was able to predict the variability of the total leaf litterfall of the three species. We conclude that, for an intimately mixed forest stand, a model that simulates leaf dispersal of individual trees is likely to be the best choice for predicting the spatial distribution of leaf litterfall. FOR. SCI. 50(6):836–847.

Satellite-based modeling of gross primary production in a seasonally moist tropical evergreen forest

A CO 2 eddy flux tower study has recently reported that an old-growth stand of seasonally moist tropical evergreen forest in Santarém, Brazil, maintained high gross primary production (GPP) during the dry seasons [Saleska, S. R., Miller, S. D., Matross, D. M., Goulden, M. L., Wofsy, S. C., da Rocha, H. R., de Camargo, P. B., Crill, P., Daube, B. C., de Freitas, H. C., Hutyra, L., Keller, M., Kirchhoff, V., Menton, M., Munger, J. W., Pyle, E. H., Rice, A. H., & Silva, H. (2003). Carbon in amazon forests: Unexpected seasonal fluxes and disturbance-induced losses. Science, 302, 1554–1557]. It was proposed that seasonally moist tropical evergreen forests have evolved two adaptive mechanisms in an environment with strong seasonal variations of light and water: deep roots system for access to water in deep soils and leaf phenology for access to light. Identifying tropical forests with these adaptive mechanisms could substantially improve our capacity of modeling the seasonal dynamics of carbon and water fluxes in the tropical zone. In this paper, we have analyzed multi-year satellite images from the VEGETATION (VGT) sensor onboard the SPOT-4 satellite (4/1998–12/2002) and the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra satellite (2000–2003). We reported temporal analyses of vegetation indices and simulations of the satellite-based vegetation photosynthesis model (VPM). The Enhanced Vegetation Index (EVI) identified subtle changes in the seasonal dynamics of leaf phenology (leaf emergence, leaf aging and leaf fall) in the forest, as suggested by the leaf litterfall data. The land surface water index (LSWI) indicated that the forest experienced no water stress in the dry seasons of 1998–2002. The VPM model, which uses EVI, LSWI and site-specific climate data (air temperature and photosynthetically active radiation, PAR) for 2001–2002, predicted high GPP in the late dry seasons, consistent with observed high evapotranspiration and estimated GPP from the CO 2 eddy flux tower.

Calculating the long-term stable nitrogen sink in northern European forests

Abstract Nitrogen accumulation rates in a boreal Scots pine monoculture in central Sweden and three groups of mixed Scots pine/Norway spruce/silver birch forests in northern Sweden are estimated by using measured and calculated litter fall data, calculated limit values for litter decomposition, and the nitrogen concentration at the limit value (Nlimit). Humus has been accumulating in these forests for 120–3000 years. The Nlimit value is determined by extrapolating a linear relationship between accumulated litter mass loss and the increasing litter N concentration. Values for foliar litter fall and Nlimit are used to calculate the quantity of an hypothesized stable N fraction remaining after accumulated mass loss has reached an asymptotic plateau (the limit value). This stable remaining amount of nitrogen is compared to measured amounts of N in the humus layers of the forests. Measured rates of N accumulation in humus range from 0.147 to 0.255 g N m–2 year–1 and differ from estimated rates of N accumulation in humus by 1.8–30.4%, the higher value possibly due to a slow succession from N-poor pine to N-rich birch, not accounted for in the model. Relating the nitrogen accumulated in these forests at maturity to a nitrogen budget based on estimated rates of nitrogen input, N2 fixation, denitrification and leaching to the mineral soil gives a good agreement of about 0.30–0.35 g N m–2 year–1 stored in humus and vegetation at forest maturity. In these forests, this low rate of N accumulation and storage can apparently continue for thousands of years until the system is “reset” by forest fire. We conclude that in undisturbed boreal forests, once N is bound in recalcitrant fractions it is stable, and that the humus is thus a long-term nitrogen sink.

Input–output analysis of macroelements in ICP-IM catchment area, Estonia

Using bulk deposition, throughfall, stemflow, soil infiltration, runoff water, litterfall data, ion mass budgets were calculated for a catchment area and for mature spruce and pine stands on it. The ions considered in mass balances were Na +, K +, Ca 2+, Mg 2+, SO 4 2−, NO 3 −, NH 4 +, HCO 3 −, and H +. Corresponding fluxes for the budgets were calculated as an average for 6 years of studies (1995–2000). Annual input–output balances of all nutrients were positive at the plot-scale, so that leaching into soil water was less than the corresponding deposition load. Deposition of Ca, Mg, Na and S into soil by precipitation exceeded input through litterfall. A proton budget approach shows that the main soil buffering process is retention of sulphate, which clearly exceeds weathering. At the catchment-scale, input–output analysis shows essential output of cations due to weathering from the soil. A distinct change in input–output balance of sulphate during study period was evident. The retention of sulphur has been replaced by its release from the catchment area.

Litter breakdown and mineralization in a central African rain forest dominated by ectomycorrhizal trees

Based on litter mass and litterfall data, decomposition rates for leaveswere found to be fast (k = 3.3) and the turnover times short (3.6mo) on the low-nutrient sandy soils of Korup. Leaf litteroffour ectomycorrhizal tree species (Berlinia bracteosa, Didelotiaafricana, Microberlinia bisulcata and Tetraberliniabifoliolata) and of three non-ectomycorrhizal species(Cola verticillata, Oubanguia alata andStrephonema pseudocola) from Korup were left to decomposein 2-mm mesh bags on the forest floor in three plots ofeachof two forest types forest of low (LEM) and high (HEM) abundance ofectomycorrhizal (caesalp) trees. The litter of the ectomycorrhizal speciesdecayed at a significantly slower rate than that of thenon-ectomycorrhizal species, although the former were richer in P and Nconcentrations of the start. Disappearance rates of the litter layer showed asimilar trend. Ectomycorrhizal species immobilized less N, but mineralized moreP, than non-ectomycorrhizal species. Differences between species groupsin K, Mg and Ca mineralization were negligible. Effect of forest type was clearonly for Mg: mineralization of Mg was faster in the HEM than LEM plots, apattern repeated across all species. This difference was attributed to a muchmore prolific fine root mat in the HEM than LEM forest. The relatively fastrelease of P from the litter of the ectomycorrhizal species suggests that thematmust allow an efficient uptake to maintain P in the forest ecosystem.

Phenology, litterfall and nutrient resorption in Avicennia marina (Forssk.) Vierh in Gazi Bay, Kenya

The phenology and litterfall of the mangrove Avicennia marina were monitored from August 1993 to November 1994 in Gazi Bay, Kenya. Phenological trends in the emergence and fall of leaves were monitored at regular intervals from 200 tagged terminal shoots distributed over 34 different trees randomly selected within three sites in a monospecific stunted A. marina stand. Litterfall data were collected using 23 litter traps randomly distributed in the same stand. The results showed a marked seasonality in leaf emergence in A. marina with a peak of 1.61±0.34 leaves per leaves present day–1 during the rainy season. Most litterfall was recorded at the beginning of the dry season. Average total litterfall amounted to 6.2±4.7 ton ha–1 year–1 with leaves contributing up to 83% of the total. Peak leaf emergence preceded peak leaf fall by approximately 1 month. Trees produced most new leaves when there were optimal conditions of runoff (nutrients), low evapotranspiration and reduced salinity during the rainy season. The average leaf longevity observed in the present study was approximately 11 months (1.1 turnover per year). Analysis of leaves of different physiological ages showed a nutrient resorption in the A. marina stand of 68% for N and 61% for P. Chloride content did not change with the ageing of leaves.

Litter fall in some European coniferous forests as dependent on climate: a synthesis

Litter fall data was available for 64 sites in Europe, most of them in Fennoscandia. Included were 48 sites with pine (Pinus spp.), mainly Scots pine (Pinus sylvestris L.), and 16 sites with spruce (Picea spp.), mainly Norway spruce (Picea abies (L.) Karst.). Regressions were calculated for needle and total litter fall against a set of climatic parameters, and the best simple relationships were obtained with annual actual evapotranspiration (AET) and other parameters including temperature, whereas for example, precipitation gave lower r values. For needle litter fall and AET using all data, the R2adj value was 0.635 (n = 64), and for needle litter for pine and spruce separately, the R2adj were 0.576 (n = 48) and 0.775 (n = 16), respectively. AET plus stand age gave highly significant relationships for both coniferous genera combined (R2adj = 0.683), and for pine and spruce separately the corresponding values were 0.655 and 0.843, respectively. Using all available data we found highly significant relationships between needle litter fall and total litter fall. For Fennoscandia, litter fall for Scots pine and Norway spruce were compared. AET versus needle litter fall gave highly significant relationships for Scots pine (R2adj = 0.448, n = 34) and for Norway spruce (R2adj = 0.678, n = 13); the relationships were significantly different from each other.

Relation Between Defoliation and Litterfall in Some Danish Picea Abies and Fagus Sylvatica Stands

Assessing defoliation and measuring litterfall are two different ways of estimating the shedding of needles and leaves from the forest canopy. Both variables can be said to reflect the crown condition, but the two methods have rarely been compared. In this study the visual observations of defoliation of individual trees were compared with sampled litterfall data for the two main tree species in Denmark, Fagus sylvatica and Picea abies. Defoliation assessments and litterfall measurements were performed in seven level II plots. Six of the stands were 40 yrs old and the remaining stand was 81 yrs old. Both a positive and a negative correlation, which were not significant, were observed between defoliation and total leaf litterfall on the beech sites. Similarly, no significant correlation was observed between defoliation and the yearly needle litterfall on the younger Norway spruce plots. However, the defoliation and the yearly needle litterfall at the old stand at Klosterhede were positively correlated on a 10% significance level. A positive correlation was also apparent at the younger stands between the defoliation and the needle litterfall from the period April-July of the same year in which defoliation was assessed. The absence of a clear connection between the two assessments is discussed. The two assessments are apparently of widely different origin, which makes comparison difficult.

Litterfall and nutrient return in seasonally flooded and non-flooded forest of the Pantanal, Mato Grosso, Brazil

Seasonally flooded evergreen forests and non-flooded deciduous and semi-deciduous forests of the Pantanal of Mato Grosso, Brazil, were studied to compare their structure and floristic composition, their production of small litterfall and its seasonal variation, as well as the nutrient input into the soil by fallen litter. The litterfall data were used to test the hypothesis that seasonally flooded forests of the Pantanal are more productive than non-flooded forests. Eight permanent plots of 0.25 ha each were established in three forest types. The clayey forest soils had low N and P concentrations, a CEC from 20 to 190 μmol g −1 and a pH from 5.1 to 6.6. All trees of ≥5 cm DBH were identified and their diameters measured. Tree density and stand basal area ranged, respectively, from 368 to 1700 ha −1 and 15.5 to 25.3 m 2 ha −1 in non-flooded and from 725 to 2005 ha −1 and 22.1 to 32.6 m 2 ha −1 in seasonally flooded forests. There were no significant differences in stem density and basal area between non-flooded and seasonally flooded forest. Species richness ranged from 4 to 17 per plot. Small litterfall (leaves, wood≤2 cm, reproductive parts, trash<2 mm) was collected monthly over three years in 25 litter traps on each plot. Dry weights and element concentrations (N, P, K, Ca, Mg, Al) of litter fractions were determined. Concentrations of P, Ca, and Mg were highest in leaf litter from plots with many deciduous species. Accumulated Al (1.4%) was found in litter from Vochysia divergens Pohl. Element accession rates were low in deciduous and high in semi-deciduous and evergreen forest. Total litterfall in non-flooded deciduous and semi-deciduous forest (4.86 to 7.71 t ha −1 year −1) was significantly lower than in seasonally flooded evergreen forest (7.53 to 10.27 t ha −1 year −1). The findings show that, despite seasonal water excess being the prominent feature of the Pantanal, it is water shortage in the dry season that limits forest productivity.

Changes in nutrient concentrations and nutrient release in decomposing needle litter in monocultural systems of Pinus contorta and Pinus sylvestris—a comparison and synthesis

Scots pine (Pinus sylvestris) and lodgepole pine (Pinus contorta) needle litters were compared in terms of nutrient composition and its change during decomposition. Initial nutrient composition differed between the species, with lodgepole pine needle litter having significantly higher concentrations of P, Mg and Mn. However, no difference was found for concentrations of N, Ca or K. Increases in concentrations of N, P and K during decomposition were significant in both litter types. For Ca the pattern of concentration changes followed a quadratic function as decomposition proceeded. Concentrations of Mg and Mn decreased in lodgepole pine needle litter. In Scots pine litter there was also an initial decrease, but it was followed by an increase in most incubations. For both Mg and Mn, changes in concentrations during decomposition differed significantly between species. In the late decomposition stages, concentrations of Mg and Mn became similar in both litter types. Nutrient concentrations generated by the models were compared with those of the humus (F and H) layer in the stands. The model was quite accurate in predicting concentrations of N and P for both species and the concentration of Mg for lodgepole pine. By contrast, it was not accurate in predicting concentrations of Ca and Mn. Nutrient release was estimated for the two species using both measured litterfall data and long‐term estimates, and regression models were used to predict concentration changes. Rates of release of P, Mg and Mn in the lodgepole pine stands were found to be about twice as high compared with those in Scots pine. Calcium was also released to a greater extent although the difference was not significant.