Quantification of Litter Fall and Estimation of Nutrient Release Through in-Situ Decomposition of Leaf Litter From Some Important Mangrove Species of Indian Sundarbans

Looking into the importance of mangrove leaf litter in regulation of sediment carbon sequestration and nutrient flux in Sundarbans ecosystem, an experiment was conducted at Jharkhali island of Sundarbans. In this experiment, collection of leaf litter-shedding from nine dominant mangrove species during December 2012 to November 2013 was donemonthly using ‘litter traps’ (1 m2) in Eco-garden on the bank of Herobhanga creek.Seasonal litter fall was highest in Geon (Excoecariaagallocha)(103 gm-2) followed by Keora (Sonneratiaapetala) (98.5 gm-2). Kal Bain (Avicennia alba) produced the highest amount (414.37 gm-2) of total annual leaf litter followed by Bruguieragymnorrhiza (410.43 gm-2). Kankra (Bruguieragymnorrhiza), Garjan (Rhizophoramucronata) and Geon (Excoecariaagallocha) dry leaf litters contained more than 50% carbon (oven dry basis). Litter from Avicennia group contained more nitrogen and carbon. Decomposition rates of various mangrove litters were estimated through twoshort-term (30 days and 52 days) in-situ experiments using mangrove leaf litter in nylon net bags (0.6 mm mesh) subjected to periodical diurnal submergence by tidalriver water at Jharkhali. During decomposition process,observation said thatmost susceptible and resistant litter with respect to mass loss were Geon (Excoecariaagallocha) (81±5.5%) and Taura (Aegialitisrotundifolia) (26±4%) respectivelyafter 30 days. The biomass retained after decomposition losses (average45±15.2%after 30 days and 56±20.2 % after 52 days) indicated the amount of carbon retained in mangrove soil and ultimately determines the carbon sequestered in soil through mangrove litter fall. The study gives important insight into contribution of different mangrove species in carbon sequestration and nutrient dynamics in mangrove ecosystem of Indian Sundarbans.

Effects of Moderate Nitrate and Low Sulphate Depositions on the Status of Soil Base Cation Pools and Recent Mineral Soil Acidification at Forest Conversion Sites with European Beech (“Green Eyes”) Embedded in Norway Spruce and Scots Pine Stands

High N depositions of past decades brought changes to European forests including impacts on forest soil nutrition status. However, the ecosystem responses to declining atmospheric N inputs or moderate N depositions attracted only less attention so far. Our study investigated macronutrient (N, S, Ca2+, Mg2+, K+) pools and fluxes at forest conversion sites over 80 years old in Central Germany with European beech (so-called “Green Eyes” (GE)). The GE are embedded in large spruce and pine stands (coniferous stands: CS) and all investigated forest stands were exposed to moderate N deposition rates (6.8 ± 0.9 kg ha−1 yr−1) and acidic soil conditions (pHH2O < 4.7). Since the understanding of forest soil chemical and macronutrient status is essential for the evaluation of forest conversion approaches, we linked patterns in water-bound nutrient fluxes (2001–2018) and in predicted macronutrient storage in the herbaceous and tree layer to patterns in litter fall (2016–2017) and in forest floor and mineral soil macronutrient stocks at GE and CS assessed in 2018. Our results exhibited 43% (Nt) and 21% (S) higher annual throughfall fluxes at CS than at GE. Seepage water at 100 cm mineral soil depth (2001–2018) of CS is characterized by up to fivefold higher NO3− (GE: 2 ± 0.7 µmolc L−1; CS: 9 ± 1.4 µmolc L−1) and sevenfold higher SO42− (GE: 492 ± 220 µmolc L−1; CS: 3672 ± 2613 µmolc L−1) concentrations. High base cation (∑ Ca2+, Mg2+, K+) concentrations in CS mineral soil seepage water (100 cm depth: 2224 ± 1297 µmolc L−1) show significant positive correlations with SO42−. Tree uptake of base cations at GE is associated especially with a Ca2+ depletion from deeper mineral soil. Foliar litter fall turns out to be the main pathway for litter base cation return to the topsoil at GE (>59%) and CS (>66%). The litter fall base cation return at GE (59 ± 6 kg ha−1 yr−1) is almost twice as large as the base cation deposition (30 ± 5 kg ha−1 yr−1) via throughfall and stemflow. At CS, base cation inputs to the topsoil via litter fall and depositions are at the same magnitude (24 ± 4 kg ha−1 yr−1). Macronutrient turnover is higher at GE and decomposition processes are hampered at CS maybe through higher N inputs. Due to its little biomass and only small coverage, the herbaceous layer at GE and CS do not exert a strong influence on macronutrient storage. Changes in soil base cation pools are tree species-, depth- and might be time-dependent, with recently growing forest floor stocks. An ongoing mineral soil acidification seems to be related to decreasing mineral soil base cation stocks (through NO3− and especially SO42− leaching as well as through tree uptake).

Lignin, cellulose and nutrient deposition in litters of Bambusa vulgaris stands in a regenerating forest in Ile-Ife, Nigeria

The lignin, cellulose and nutrient deposition of litters were assessed in four 0.06 ha plots of Bambusa vulgaris stands in a regenerating forest in Ile-Ife, Nigeria, 35 years after ground fire, with a view to providing information on these parameters which are generally lacking in the forest ecosystem. The collected litters were sorted into leaves and twigs, oven-dried at 70 °C to a constant weight, ground and analysed for lignin, cellulose and nutrients. The total lignin and cellulose content in the litters showed significant (p≤0.05) monthly variation. There was no significant (p ≥ 0.05) difference in the monthly nutrient deposition of Na, Mg, K, Fe, N, P, Mn, Zn and Cu, but there was significant difference in the monthly nutrient deposition of C and Ca through the litter fall fraction (p ≤ 0.05) in the bamboo stands in the secondary rainforest. The depositions of C, N, Ca, Mg and Cu were higher in the bamboo stands but lower in Na, Mn and Zn deposition in 1990 and 2013 studies. The bamboo stands contributed significantly to the carbon sequestration, nutrient dynamics and regeneration status of the forest.

Biological Methods of Fixing of Slopes Susceptible to Water Erosion in Western Siberia

The effectiveness of the biological method of fixing slopes folded by dusty sands is shown. The proposed methods include applying a 3–5-cm layer of peat-sand mixture to the surface of the slopes, arranging retaining walls to prevent washing off of the applied soil, applying fertilizers and sowing perennial grasses. A year later, dense turf is formed in the experimental plots with the presence of litter fall from last year's herbaceous plants. In this case, in contrast to the unfixed part of the slope, the development of erosion processes in the sown areas does not occur.

Formation of Soil Chemical Environment in Coastal Pinus thunbergii Parlatore Forest in Southwestern Japan

We investigated the chemical properties of precipitation and litter fall, and their effects on soil chemistry, in a coastal forest consisting of pure Pinus thunbergii stands, Pinus-dominated stands with broadleaf trees in the understory, mixed stands of Pinus and evergreen broadleaf trees, and evergreen broadleaf stands. Throughfall pH in the pure Pinus stand was significantly lower than those in the other three stands, and the soil in the pure Pinus stand was determined to be acidic (pH = ca. 5.0). In Pinus-dominated stands with broadleaf species in the understory, precipitation had a neutralizing effect in the foliage of broadleaf species in the understory of the Pinus stand and the pH levels of their surface mineral soil were significantly higher than those in the pure Pinus stand. The soil pH level was low in the pure Pinus stand, and then increased with an increasing dominance of broadleaf species in the understory. The soil pH was lowered with an increasing dominance of broadleaf species in the canopy layer. A litter layer consisting of decomposable litter of broadleaf species with low C/N ratio acidified precipitation that was deposited as throughfall on the litter surface. Nitrates in the soil-extracted water from the mixed stand and from the evergreen broadleaf stand were significantly higher than the nitrates of stands with high dominance of Pinus. Higher nitrogen flux in the mixed stand and in the evergreen broadleaf stand, as well as a lower C/N ratio of the litter of broadleaf species, accelerated nitrogen accumulation in the soil in stands with high broadleaf species dominance in the canopy compared to the Pinus-dominated stand. Thus, the accumulation of nitrogen in the soil through litter fall is a possible factor that promotes succession from Pinus stands to evergreen broadleaf stands.

Early responses of elevated nutrient input on above-ground net primary production of a lower-montane tropical forest in Uganda

&lt;p&gt;Nutrient availability in tropical forest ecosystems plays a critical role in sustaining forest growth and productivity. Observational evidence for nutrient limitations on net primary productivity (NPP) in the tropics is rare yet crucial for predicting the impacts of human-induced changes on tropical forests, particularly for underrepresented tropical regions in Africa. In an ecosystem-scale nutrient manipulation experiment, we assessed the response of different components of above-ground net primary production (ANPP) to nutrient addition of nitrogen (N), phosphorus (P), potassium (K) and all possible combinations (NP, NK, PK, and NPK) at rates of 125 kg N ha&lt;sup&gt;-1&lt;/sup&gt;yr&lt;sup&gt;-1&lt;/sup&gt;, 50 kg P ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; and 50 kg K ha&lt;sup&gt;-1&lt;/sup&gt;yr&lt;sup&gt;-1&lt;/sup&gt;.&lt;/p&gt;&lt;p&gt;We established 32 (8 treatments &amp;#215; 4 replicates) experimental plots of 40 &amp;#215; 40 m&lt;sup&gt;2&lt;/sup&gt; each and measured stem growth of over 15,000 trees with diameter at breast height (dbh) &amp;#8805; 1 cm as well as litter production and above-ground woody biomass production (AWBP), of a lower-montane tropical forest (1100 m a.s.l.) in northwestern Uganda.&lt;/p&gt;&lt;p&gt;After 18 months of nutrient addition, we found that different aspects of ANPP, including litter production and AWBP are controlled by multiple soil nutrients. Specifically, we measured higher total fine-litter production in the N (13.6 &amp;#177; 1.4 Mg ha&lt;sup&gt;-1 &lt;/sup&gt;yr&lt;sup&gt;-1&lt;/sup&gt;) and K (13.3 &amp;#177; 1.8 Mg ha&lt;sup&gt;-1 &lt;/sup&gt;yr&lt;sup&gt;-1&lt;/sup&gt;) addition plots than the control (11.1 &amp;#177; 0.6 Mg ha&lt;sup&gt;-1 &lt;/sup&gt;yr&lt;sup&gt;-1&lt;/sup&gt;) plots. Both reproductive litter (flowers and fruits; 10% of total fine-litter fall) and leaf litter (62% of total fine-litter fall) significantly increased with K addition. In general, fine-litter production in our plots is higher than what has been reported so far for lower-montane tropical forests. Increased AWBP is associated with N addition plots. The response of trees to nutrient addition however, varied with tree sizes. Trees with dbh between 10 &amp;#8211; 30 cm increased significantly in AWBP under PK addition. There was no effect of nutrient addition associated with either smaller (1 &amp;#8211; 10 cm dbh) or larger trees (dbh &gt; 30 cm). The medium-sized trees which may have experienced resource competition but have now transitioned into the canopy layer (exposed to sunlight) are able to use additional nutrient for active growth. In contrast, bigger trees may allocate extra nutrient for reproduction and leaf-vitality, while smaller trees remain shaded, co-limited by sunlight and therefore unable to utilize increased available nutrients for stem diameter growth. ANPP increased by 39% with N addition and marginally by 23% with K additions relative to the control. In conclusion, our experiment provides evidence of N and potentially K limitation of ANPP in this lower-montane tropical forest, and highlights that, in a highly diverse ecosystem different components of ANPP may be regulated by multiple nutrients.&amp;#160;&lt;/p&gt;

Nutrient sources in four forest watersheds in Japan: the contribution of precipitation, weathering and litter fall

&lt;p&gt;Base cation such as calcium and potassium is important nutrient for tree growth in forest ecosystems.&amp;#160; Major sources of basic cation to forest soil are precipitation, weathering of parent material and litter fall.&amp;#160; Weathering rate of basic cation is estimated from the input from precipitation, runoff from stream and uptake by vegetation. &amp;#160;Nutrient cycling of many Japanese forest ecosystems has been studied but information about the contribution of these sources is limited.&amp;#160; This study compared three nutrient sources in four forest watersheds in Japan.&amp;#160; These are Oyasan (Gunma Pref.), Kamikamo (Kyoto Pref.), Kiryu (Shiga pref.) and Takatori (Kochi Pref.).&amp;#160; We calculated nutrient budget of potassium, calcium and magnesium.&amp;#160; The rate of rock weathering of base cation ranged from 0.22 to 4.37 kmolc ha&lt;sup&gt;-1&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; and increased in the order of Kamigamo &lt; Kiryu &lt; Oyasan &lt; Takatori.&amp;#160; In potassium cycling, the contribution of litter fall was greater than that of weathering or precipitation.&amp;#160; The runoff of calcium and magnesium from soil was greater in Takatori, where the rate of weathering was high.&amp;#160; Although the rate of weathering varied substantially among forest watersheds, the annual flux of litter fall was relatively constant.&amp;#160; Similar calculation was applied for nitrogen cycling and the&amp;#12288;source from soil was treated as that from nitrogen accumulated during the past pedogenesis. &amp;#160;Nitrogen input from the accumulated soil source was 36 % in Oyasan whereas that in other three watersheds was 0%. Oyasan was considered as a nitrogen-saturated forest and the result of the study suggest the ecosystem relies on different nitrogen source.&lt;/p&gt;