Litterfall Nutrient Research Articles

Nutrient concentrations in litterfall from some western conifers with special reference to calcium

Foliar litterfall nutrient concentrations were analysed for selected members of Taxodiaceae and Cupressaceae families andPseudotsuga menziesii for two arboreta in western Oregon and Washington. Nutrient results between arboreta show similar concentrations with the exception of magnesium, which may be the result of historical land use. Nutrient concentrations between species vary considerably.Pseudotsuga menziesii is particularly distinctive from the Cupressaceae and Taxodiaceae by retaining large amounts of phosphorus and potassium. Taxodiaceae is distinctive by high concentration of Mg while Cupressaceae retains calcium, especiallyChamaecyparis nootkatensis. Results suggest that all members of Taxodiaceae and Cupressaceae retain considerably more Ca than Pinaceae in foliar litter.

Influence of elevated ecosystems levels on litter decomposition and mineralization

Litter decomposition was studied at two forested watersheds in east Tennessee which differed primarily in their past history of atmospheric S input. Cross Creek Watershed, located near a large coal-fired power plant, has received greater S inputs than the more remote Camp Branch Watershed. Decomposition was estimated through the measurement of forest floor respiration, litter microflora populations, litter and soil microarthropod populations, and litter nutrient status. Average forest floor respiration rates were very similar, 6.78 g CO2 m−2 day−1 or 2472 g m−2 yr−1 at Camp Branch and 6.86 g CO2 m−2 day−1 or 2505 g M−2 yr−1 at Cross Creek. Fractional loss rates provided estimates of annual decay rates (k) of 0.35 and 0.39 for Camp Branch and Cross Creek, respectively. Litter decomposition was estimated to contribute 23% of the total CO2 output at Camp Branch and 26% at Cross Creek, while root respiration accounts for about 43 to 46%. Bacterial and fungal populations were about equal in size at both watersheds, with bacteria averaging 100 × 106 g−1 of litter and fungi 23 × 106 g−1 of litter. Total numbers of arthropods averaged 34% greater at Camp Branch. Acarina populations averaged 59% higher at Camp Branch, while Collembola numbers were about equal at the two watersheds. Nutrient mobility in the litter and soil was similar at both watersheds. The order of decreasing mobility was K, Mg, Ca, S, N, and P. Litterfall nutrient concentrations were slightly higher for all elements at Cross Creek, resulting in greater litter concentrations of Ca and Mg. Litter concentrations of S and N, however, were significantly greater at Camp Branch, indicating watershed differences in the loss rates and cycling processes of these elements. There were no differences between the loss rates or litter concentrations of P, K, and Na at either site. Overall, decomposition was similar at the two watersheds. Historic S inputs do not appear to have had a major effect on decomposition rate or decomposer organisms with the possible exception of lowered arthropod populations at Cross Creek.

NUTRIENT CYCLING IN MOIST TROPICAL FOREST

Early studies of nutrient cycling in moist tropical forests described productive forests rich in nutrients (98, 114, 176) in which rates of primary production and the amounts of nutrients cycled clearly exceeded those in temperate zone forests. Reviews of global-scale patterns in biomass, production, and nutrient cycling reported these results as representative of tropical forests (130, 175). At the same time, tropical forest soils were described as acid, infertile clays that harden irreversibly to laterite when cleared (106), or as bleached quartz sands low in mineral nutrients (88). This apparent paradox was crystallized by Whittaker (174) in the statement The tropical rain forest thus has a relatively rich nutrient economy perched on a nutrient-poor substrate (p. 271). Reviews of more recent research on overall patterns of mineral cycling in the tropics (78, 124), and of important components such as biomass (20, 21), litterfall nutrients (123, 164), and decomposition (5), clearly show that patterns of nutrient cycling in tropical forests are diverse. It makes no more sense to describe a 'typical' tropical forest than a 'typical' temperate forest (33, 151). Variations in mineral cycling nonetheless follow coherent, explicable patterns in tropical forests. Our purposes in undertaking this review are: (a) to illustrate the patterns of nutrient cycling in moist tropical forests; (b) to identify the mechanisms which regulate those patterns; and (c) to show how those patterns affect the productivity, physiology, and population biology of tropical forests and their large-scale linkages with aquatic ecosystems and the atmosphere. We emphasize the cycling of nitrogen, phosphorus, potassium, calcium, and magnesium; these are the best-studied soil-derived nutrients, and they are the nutrients most likely to limit primary production and other ecosystem functions.

Litter and forest-floor dynamics in aPinus resinosa plantation in Wisconsin

Breakdown of dry matter and release of nutrients from decomposing leaf litter and forest-floor material were measured in a 34-year-old red pine (Pinus resinosa Ait.) plantation in central Wisconsin using (1) leaf-litter bags (2) litterfall and forest-floor nutrient data and an exponential decay function, and (3) nutrient flux data and a mass balance equation. After one year of decomposition, 77% of the original dry matter in leaf-litter bags remained. The release of macronutrients in decomposing leaf litter was K>Mg>P, S>N>Ca, and the release of micronutrients and aluminum was Mn, B>Al>Cu>Zn. Nitrogen in decomposing leaf litter showed the leaching, accumulation, and final release phases delineated by Berg and Staff4. Half-lives of dry matter and nutrients in the forest floor ranged from 0.5 (K) to 39 (Al) yr. Forest-floor turnover rates of the various elements followed the same trends as in leaf-litter bags except that Ca turned over more readily than P, S, and N and Zn turned over more readily than the other micronutrients. A forest-floor nutrient balance sheet confirmed that the macronutrients N and Ca are accumulating most readily in the forest floor. The overall implications of these trends for tree nutrition are discussed.

Nutrient accumulation by trees and understorey shrubs in an age-series of Eucalyptus diversicolor F. Muell. stands

Nutrient composition of aboveground components of overstorey trees and understorey shrubs were measured in four even-aged stands of E. diversicolor (4-, 8-, 11- and 36-years-old) and in a mature stand. The even-aged stands had regenerated from seed after cleafelling and slash-burning of native forest, and understories in the younger stands were the same age as trees. However in the 36-year-old and mature stands understories had regenerated from seed after prescribed burning and were 9 and 14 years of age, respectively. Trymalium spathulatum and the legume Bossiaea laidlawiana were the dominant understorey species in all stands. Aboveground nutrient pools varied less than biomass with stand age. This is because much of the increase in biomass as stands develop is due to production of heartwood, in which concentrations of nutrients are low. Understories contained a large proportion of the nutrients in all stands. In the 8- and 11-year-old stands about 46% of the aboveground biomass was understorey and this contained 49–56% of the N and S. In the 36-year-old stand, understorey contained 35% of the N and S although it was only 10% of the aboveground biomass. There was relatively more of the nutrient elements other than N and S in E. diversicolor than in understorey species in the 4-, 8-, and 11-year-old stands. In all five stands B. laidlawiana was an important component of the understorey, amounting to 51–93% of the biomass and containing 72–97% of the N. The leaves of B. laidlawiana contained about 40% of the P, and 31–36% of the N, S, Mg, Zn and Mn but comprised only 6–8% of the aboveground weight. Average rates of nutrient accumulation in aboveground biomass decreased with increasing stand age. This decrease was generally balanced by an increase in the amount of nutrients in litterfall so that, with the exception of mobile nutrients, the annual uptake of nutrients (accumulation plus litterfall) by vegetation was similar for each of the even-aged stands. Understorey accounted for a large proportion of the nutrients accumulating in aboveground biomass, particularly in the 36-year-old stand, where N, K, S, Zn and Cu accumulated more rapidly in understorey shrubs than in trees. The study suggests that the understorey plays a significant role in the nutrition of E. diversicolor stands.

Nutrient accessions to the forest floor in karri ( Eucalyptus diversicolor F. Muell.) forests of varying age

Nutrient accessions to the forest floor in rainfall, throughfall and stemflow from the understorey and tree strata were measured in karri ( Eucalyptus diversicolor F. Muell.) forest of south-west Western Australia. These data, for stands aged 2, 6, 9, and 40 years and for mature forest, were compared with annual accessions of nutrients in litterfall. With increasing age of the stands, the concentration and amounts of Ca, K, Mg, Na and Cl in throughfall increased. The amounts of Mg, Na and Cl in stemflow from the overstorey were also greatest in the older stands. Although concentrations of nutrients in stemflow from the tree stratum were higher than from the understorey, the quantities of nutrients transported to the forest floor in stemflow from the understorey were greater because of its greater volume. Rainfall is the major source of Na (64–91%) and Cl (51–79%) and it also contributes significantly to Mg (19–50%) accessions. Of the nutrient pathways between canopy and forest floor, litterfall accounts for the largest proportion of N (89–93%), Ca (80–87%) and P (67–79%) recycled in the karri forest. About equal amounts of K are transferred in litterfall, throughfall and stemflow with approximately 80% of stemflow K originating from the understorey strata.

Nutrient fluxes in litterfall and decomposition in four forests along a gradient of soil fertility in southern Ohio

To determine how soil nutrient availability influences nutrient cycling, fluxes of nutrients through litterfall and decomposition were determined for four forest stands similar in all respects except soil nutrient availability and microclimate, within Neotoma Valley, a small watershed in southern Ohio, U.S.A. Litterfall varied from 10 to 60% among sites while nutrient concentrations and masses in new leaf litter varied as a function of extractable soil nutrient levels. Mass loss from litterbags was significantly higher in more fertile sites. Stepwise regression indicated that initial litter nitrogen and phosphorus concentrations were strongly correlated with relative decomposition rate while lignin concentration and microclimate variables were only correlated weakly. Thus, both litterfall nutrient transfers and decomposition rates were under the control of soil nutrient levels. Nitrogen was immobilized in litter at all sites during the 1st year of decay; litter from more fertile sites mineralized nitrogen during the 2nd year, while that from less fertile sites continued to immobilize nitrogen. Phosphorus and calcium mineralization rates were strongly correlated with the availability of these elements in the soil. Magnesium and potassium were leached rapidly from litter; amounts mineralized were correlated with amounts in litterfall. Interrelations among soil fertility, litterfall, and nutrient mineralization, as well as litter redistribution, are discussed as processes important in the development and maintenance of the soil fertility gradient in this watershed.

Litter-Fall In a Pinus radiata Forest: The Effect of Irrigation and Fertilizer Treatments

(1) A 15 year-old Pinus radiata plantation near Sale, Victoria, Australia, was irrigated with waste-water for 3 years. A litter-fall of 400 g m-2 year-1 was recorded in irrigated plots compared with 320 g m-2 year-1 in non-irrigated plots. The increase in litter-fall resulted from an increase in the production of new needles and greater shedding of older needles. Periods of soil water deficit caused increased shedding of needles in both irrigated and non-irrigated plots. (2) Irrigation with waste-water increased the concentration and amounts of most elements in the litter-fall which were present in the waste-water. Whilst the effect of irrigation on tree growth and the rate of turnover in organic matter was beneficial during the period of study, increases in pH and alkalinity in the standing litter and soil could eventually reduce the availability of iron and other trace elements. Superphosphate fertilizer decreased litter-fall slightly and the concentration of most elements except phosphorus. (3) Distinct seasonal patterns were observed in the concentrations of nutrients in litterfall and the following hypothesis has been proposed to explain these seasonal changes: increasing stress during spring and summer caused abscission of mature needles to occur more rapidly and higher in the crown, resulting in higher concentrations of N, P and K in falling litter. Male strobili contained very low concentrations of Ca and a sharp reduction in the concentration of this element occurred in litter-fall when strobili were shed in spring. Seasonal patterns observed in the concentrations of N, P and K in litter-fall were the reverse of those found in living foliage. The efficiency of nutrient withdrawal thus appeared to reach maximum values in winter and minimum values in summer.

Litter fall and nutrient cycling in karri (Eucalyptus diversicolor F. Muell.) forest in relation to stand age

AbstractAnnual litter fall, nutrient concentrations in litter components and annual weight of nutrients in litter fall have been estimated for karri forest stands aged 2, 6, 9 and 40 years and in mature forest. The weight of litter falling annually increases with stand age, ranging from 1.13 t/ha in 2‐year‐otd regeneration to 9.45 t/ha in mature forest. This increase is due mainly to greater amounts of twigs, bark and fruit falling in older stands. Leaf fait is relatively independent of stand age once the canopy of regenerating stands closes and the understorey has developed.Concentrations of N, P, K, S and Mn in karri leaf litter differ significantly between sites and the differences appear to be related to stand age. Highest levels of these elements are found in karri leaf litter from the youngest stand and the concentrations decrease with increasing stand age. The amounts of annual litter fall and of nutrients cycling in litter are among the largest reported for Australian forests. In particular cycling of Ca, K and Mg in mature karri forest is greater than has been reported for any other eucalypt forest. Karri forest understorey plays a key rote in nutrient cycling in these ecosystems, contributing 30–70% of the weight of many of the nutrients in the leaf component of titter. Understorey leaf material is particularly important in the cycling of N, S and the micro‐nutrients Cu and Zn.

The Role of Understory Vegetation in the Nutrient Cycle of Forested Ecosystems in the Mountain Hemlock Biogeoclimatic Zone

The biogeochemical role of understory vegetation was investigated in three sites representing a typical topographic sequence of xeric, mesic, and hygric site types characteristics of the Mountain Hemlock Biogeoclimatic Zone. Overstory biomass on the three sites was estimated to be 60.9, 55.7, and 34.5 kg/m2 for the hygric, mesic, and xeric site types, respectively. Average values for understory biomass were: 44.1, 66.1, and 309 g/m2 for the hygric, mesic, and xeric site types. Understory aboveground production (UAP) values of 26.0, 14.2, and 63.1 g°m—2°yr—1 for the hygric, mesic, and xeric site types were equivalent to 11.3, 6.1, and 48.6% of the estimated overstory aboveground production. The understory was found to cycle a much greater proportion of its total nutrient (N, P, Ca, Mg, K, Zn, Cu) standing crop annually compared to overstory. Approximately 80% of the macronutrients present in the understory standing crop are found in the understory annual production on the hygric site type. Estimates of 17.6, 8.3, and 20.6 g°m—2°yr—2 of total understory aboveground litterfall (exclusive of the moss layer) were obtained for the hygric, mesic, and xeric sites, respectively. Understory was shown to return a significant proportion of the litterfall nutrients on a yearly basis, the bulk of which was retuned as a single pulse during the first autumn snowfall. Understory vegetation above the moss layer was shoen to have a significant effect on the quantity of nutrients present in throughfall precipitation. The effect was seasonal with PO4—P, NO3—N, and NH4—N being removed in the spring and Ca, Mg, and K being added to overstory throughfall in the autumn. Modifications of water chemistry previously attributed to the forest floor may in some cases reflect unmeasured influences of understory vegetation.

Nutrient Changes in Decomposing Loblolly Pine Forest Floor

AbstractIn two loblolly pine stands (Pinus taeda L.), 11 and 32 years of age at study inception, nutrients in litterfall and throughfall were measured, and declines in nutrient content were observed as forest floor layers decomposed for up to 8 years. The forest floors up to 8 years of age in the two stands had similar rates of nutrient release. After 8 years of decomposition, 67% of the C, 27% of the N, 63% of the P, 91% of the K, 67% of the Ca, 79% of the Mg were released from the forest floor materials. In the younger stand, release from the forest floor accounted for 34, 59, 47, and 65%, respectively, of the N, P, K, Ca, and Mg assimilated annually into the aboveground biomass. In the older stand, the forest floor release accounted for 86, 104, 73, 72, and 71%, respectively, of the N, P, K, Ca, and Mg, indicating that as the stand matures, the importance of the forest floor increases in the nutrient cycling process. Nitrogen content of the forest floor appeared to increase through the third year of decomposition and then to decrease when needles and branches were assumed to be the only forest floor inputs. However, when fine particles and throughfall were included as forest floor inputs, no increase in forest floor N was observed.

Nutrient Cycling in a Eucalyptus obliqua (L'hérit.) Forest. I. Litter Production and Nutrient Return

Total litter fall in mature Eucalyptus obliqua forest is typical for warm temperate forest, in the range 3.6-5.5 t ha-1 yr-1. Fifty per cent of the litter fall occurs in the summer months, and the seasonal rate of litter fall is dependent primarily on temperature. The concentration of nutrients in litter fall varies significantly throughout the year. Prior to litter fall, about 70% of the phosphorus is withdrawn from that portion of the biomass which is to fall as litter and the amount of phosphorus cycled in the litter is therefore very small. At the other extreme, calcium is immobilized in large quantities immediately prior to litter fall. The internal, or 'biochemical', cycling of phosphorus is probably of major significance in the functioning of eucalypt forests on Australian soils characterized by a low phosphorus content.

Litter production and forest floor nutrient dynamics in pine and hardwood stands of New Brunswick, Canada

Biomass and nutrient transfer (N, P, K, Ca, Mg) of overstory (branches and leaves) and understory litter fall were examined over a two year period in four jack pine stands aged 16, 29, 49 and 57 years and four mixed hardwood stands aged 7, 17, 20 and 29 years. Relative amounts of the five nutrients in litter fall for both series of stands were N > K ≷ Ca > P = Mg. Return of mineral elements to the forest floor was generally twice as high on the hardwood stands as for similarly aged pine stands. Overall return of nutrients plotted versus stand age generally exhibited a plateau relationship, with relatively little difference among stands; however, some exceptions occurred. Understory contribution to litter fall was very important on these stands, since in most cases the nutrient mass in understory litter was usually similar to or higher than that from the tree layer. Data on forest floor biomass, nutrient distribution and turnover rates of these stands were also presented; mobility of nutrients in the forest floor was in the order K > Mg ≥ P ≥ Ca ≥ N.

Effect of Nitrogen Supply on Nutrients in Litter Fall and Crown Leaching in a Stand of Corsican Pine

In a closed-canopy forest only a small proportion of the annual nutrient uptake becomes permanently immobilized in structural tissue, the remainder returns to the soil through litter fall and crown leaching (Stenlid 1958). Little is known of the relative importance of these two pathways, partly because of the difficulty of separating true crown leaching from the wash down of air-borne salts that have previously been deposited on the surface of the trees (Attiwill 1966). This paper presents values for nutrient content in the litter that fell beneath pole-stage Corsican pine (Pinus nigra var. maritima (Ait.) Melv.) over a period of six years, together with results from a two-year study of the movement of nutrients in rainwater. The term 'gain' is used to denote the total quantity of nutrients returned to the soil by the rainwater, i.e. both the wash down of deposited aerosols and crown leaching.