Leaf Litter Production Research Articles

Leaf litterfall, decomposition and nutrients release in a Seasonal Semideciduous Forest in Southern Brazil

Biogeochemical cycling study of ecosystems and their functioning are fundamental for planning conservation practices and management of forest remnants in Brazil. The objective of the study was to characterize the leaf litterfall production rate and the nutrients release via decomposition in a fragment of Seasonal Semideciduous Forest, in Southern Brazil, in advanced stage of regeneration. For two years, evaluations of litterfall and leaf litter decomposition (using the mass loss method with litterbags) were performed monthly, as well as their nutrient content analysis. Annual input of leaf litterfall was 4,532.7 kg ha-1 of dry matter, which promoted, for the two-year period, a supply of 195.5, 9.2 and 55.3 kg ha-1 of N, P and K, respectively. The litter nutrients use efficiency followed the decreasing order P > K > N. The annual decomposition constant for leaf litter was 1.16, reaching a half-life at 215 days, making 84.4% N, 72.7% P and 92.9% K available at the decomposition end of two years. In the two years of collection, the largest deposition rate of litter occurred in the spring, with the highest peak in October, indicating a seasonal deposition behavior. The forest fragment presents high production of leaf litter (66% leaves) and input of N. The rapid decomposition of leaf litter contributes to the release of nutrients over time, N and K initially, and P in the long run. P is limited due to the high efficiency of its use.

Reduced litterfall and decomposition alters nutrient cycling following conversion of tropical natural forests to rubber plantations

Natural tropical landscapes have been continuously altered by land use change and other climate factors. Forest management practices have transformed massive tropical forests into rubber plantations throughout mainland Southeast Asia and Southwest China. However, the effect of the forest-to-plantation conversion on ecosystem functions associated with plant litter is limited. Here, we compare litterfall production, decomposition, nutrient return and nutrient use efficiency between a tropical natural forest (TNF) and a monoculture rubber plantation (MRP) in Xishuangbanna (China) over three years. Annual mean litterfall production was significantly higher in TNF (10.92 Mg ha−1 yr−1) than in MRP (5.23 Mg ha−1 yr−1). Production of leaf litter was positively correlated to that of total litterfall, suggesting that leaf litter could be reliably estimated from total litterfall. Temperature and solar radiation are dominant drivers of seasonal variation of litterfall production. The litterfall production was more sensitive to climate variables in MRP. The average stand litter and the decomposition quotient were 1.8 and 1.2 times greater in TNF than in MRP, respectively. The total nutrient return to the forest floor was 2.1 times higher in TNF (5.66 Mg ha−1 yr−1) than in MRP (2.76 Mg ha−1 yr−1); the return of each mineral element was significantly lower in MRP relative to TNF. The nutrient return preferentially occurred during the cold and dry seasons, which was consistent with the trend of litterfall. Relatively high N, P, Ca, and Mg use efficiencies were observed in MRP in line with their deficiency in the present tropical soils, indicating that rubber trees likely possess an efficient nutrient uptake mechanism to facilitate their adaption to oligotrophic habitats. Our results suggest that the large scale transformation of tropical forests to rubber plantations could alter the biogeochemical cycles related to litterfall, and thus possibly affect the resilience of ecosystems to climate variation. An increasing organic matter input in rubber monoculture may favor the sustainable development of rubber cultivation.

Effects of Increased Drought in Amazon Forests Under Climate Change: Separating the Roles of Canopy Responses and Soil Moisture

AbstractThe Amazon forests are one of the largest ecosystem carbon pools on Earth. Although more frequent and prolonged future droughts have been predicted, the impacts have remained largely uncertain, as most land surface models (LSMs) fail to capture the vegetation drought responses. In this study, the ability of the LSM JSBACH to simulate the drought responses of leaf area index (LAI) and leaf litter production in the Amazon forests is evaluated against artificial drought experiments. Based on the evaluation, improvements are implemented, including a dependency of leaf growth on leaf carbon allocation and a better representation of drought‐dependent leaf shedding. The modified JSBACH is shown to capture the drought responses at two sites and across different regions of the basin. It is then coupled with an atmospheric model to simulate the carbon and biogeophysical feedbacks of drought under future climate. We separate the drought impacts into (a) the direct effect, resulting from drier soil and stomatal closure, which does not involve a change in canopy structure, and (b) the LAI effect, resulting from leaf shedding and involving canopy response. We show that the latter accounts for 35% of reduced land carbon uptake (9 ± 10 vs. 26 ± 7 g/m2/yr; mean ± 1 sd) and 12% of surface warming (0.09 ± 0.03 vs. 0.7 ± 0.07 K) during the late 21st century. A north‐south dipole of precipitation change is found, which is largely attributable to the direct effect. The results highlight the importance of incorporating drought deciduousness of tropical rainforests in LSMs to better simulate land‐atmosphere interactions in the future.

Produksi Serasah Daun Mangrove di Pulau Manomadehe Kecamatan Jailolo Selatan Kabupaten Halmahera Barat

The mangrove ecosystem is one of the ecosystems with high productivity due to the input of organic matter from litter. Litter production is the main supporter of fisheries potential, namely as a food source for aquatic biota. On Manomadehe Island, the community still continues to cut down mangroves to be used as firewood and building materials. Activities like this will result in damage to the mangrove forest and a decrease in the amount of litter production. Research objectives 1. To determine the amount of mangrove leaf litter production on Manomadehe Island, South Jailolo District, West Halmahera Regency. 2. Knowing the rate of decomposition of mangrove leaf litter on Manomadehe Island, South Jailolo District, West Halmahera Regency. This research was carried out in June-August 2020 using the purposive sampling method to determine stations, density (line transect plot), and litter-trap litter production. In general, the composition of mangrove species found at the study site on Manomadehe Island consisted of 3 families with 6 species (Rhizophora stylosa, Rhizophora apiculata, Rhizophora mucronata, Sonneratia alba, Avicennia marina, Avicennia lanata). Total production of mangrove leaf litter is 1276,59 grams/m2/60days, the highest is at Station 1 589,80 grams/m2/60days, Station 2 is 419,59 grams/m2/60days, Station 3267,21 grams/m2/60days. The highest litter contributor was Rhizophora stylosa 424,25 grams/m2/60days. Rhizophora apiculata 340,79 grams/m2/60days, Sonneratia alba 336,94 grams/m2/60days, Rhizophora mucronata 99,26 grams/m2/60days, Avicennia lanata 38,55 grams/m2/60days, Avicennia marina species are 36,80 grams/m2/60days.

Determination of Nutrient Contents in the Leaf Litter of <i>Diospyros crassiflora</i> S. (Hiern-FWTA) Plantation in Okwuta-Ibeku, Umuahia, Abia State, Nigeria

Determination of nutrient contents in Diospyros crassiflora leaf litter was carried out in the Forestry Research Institute of Nigeria (FRIN), Okwuta-Ibeku, Umuahia, Abia State, Nigeria in 2016 and 2017. Three 1 m × 1 m trays were randomly positioned for collection of leaf litter production from 4/5 years old Diospyros crassiflora species in each block (10 m × 25 m) within the plantation totaling 1.5 ha. A Randomised Complete Block Design (RCBD) with three replicates was used to study the mean monthly leaf litterfall of Diospyros crassiflora. Leaf litter was collected from each of the three litter trays per block and placed in paper bags every 28th day of each month from January-December in 2016 and in 2017. Fifteen grammes (15 g) of properly mixed and oven-dried samples of D. crassiflora leaf litter were milled and sieved in 1 mm sieve; 0.3 g was used to determine nutrient elements and their concentrations. The data obtained from mineral nutrient contents of D. crassiflora leaf litter was analysed using analysis of variance. Result reveals the mean concentrations of nitrogen (1.41 and 1.41 mg·l-1), phosphorus (0.18 and 0.18 mg·l-1), potassium (0.68 and 0.68 mg·l-1), sodium (0.35 and 0.30 mg·l-1), calcium (1.57 and 1.56 mg·l-1), magnesium (0.32 and 0.31 mg·l-1), chlorine (0.25 and 0.24 mg·l-1), Organic carbon (0.03 and 0.03 mg·l-1) and Organic matter (1.17 and 1.18 mg·l-1) etc. in D. crassiflora leaf litter in January-December (2016 and 2017). The study shows almost uniform distribution of mineral elements concentrations in 2016 and 2017.

Production of Rhizophora Mangrove Leaf Litter in The Sungai Bersejarah Mangrove Ecosystem, Siak Regency

The mangrove ecosystem is one of the coastal ecosystems that has important ecological roles and functions in supporting marine and fishery resources. Marine and fisheries resources are largely determined by the contribution of mangrove litter. The aims of this study was to determine the production of Rhizophora mangrove leaf litter in Sungai Bersejarah mangrove ecosystem, and to determine the value of environmental parameters related to litter. The research was conducted in January until March 2021 in Sungai Bersejarah mangrove area Kayu Ara Permai, Siak Regency. Line transect plot were used to calculate the density of Rhizophora. Rhizophora litter production was measured using the trap net method placed at three sampling site. Three litter trap nets measuring 1 m x 1 m are placed at each station. Rhizophora tree density ranges from 316 - 444 ind./ha. The production of Rhizophora mangrove leaf litter in Sungai Bersejarah mangrove ecosystem was 0.82 – 1.39 g/m2/day (3.00 – 5.09 ton/ha/year), average was 4.11 ton/ha/year. Analysis of variance test showed that there was a significant difference in Rhizophora leaf litter production between sampling points with different Rhizophora tree densities (p<0.05). Mangrove vegetation density has a moderate relationship (r=0.43) to the production of Rhizophora mangrove leaf litter. Environmental parameters indicate that the condition of the Sungai Bersejarah mangrove ecosystem is still good and can support the life of mangrove vegetation.

Linking soil biodiversity and ecosystem function in a Neotropical savanna

Conserving the remaining savanna ecosystems in the Brazilian savanna (Cerrado) — a global biodiversity hotspot that stores carbon and provides water to a large portion of South America — requires understanding the ecological processes maintaining their function. Nutrient cycling supports savanna function via plant litter production and decomposition by soil fauna, releasing nutrients for plant and soil organism uptake. Soil biodiversity and biogeochemistry linkages with litter dynamics in Neotropical savannas under a changing climate are poorly understood. Here, we combined two years of rainfall seasonality, leaf and wood litter production and decomposition with soil epigeic fauna abundance — the number of ground-surface dwelling invertebrates collected through pitfall traps — taxa richness, Shannon's diversity and Pielou's evenness, and 16 soil biogeochemical variables measured in 12 plots of preserved savanna. Rainfall seasonality modulated the mean soil epigeic fauna diversity and evenness across all plots, which were highest in the rainy season, in contrast to litterfall rates, which peaked in the dry season. In the dry season (April to September), the Formicidae family was the most abundant with 50% of all individuals, while in the rainy season (October to March), the Isoptera order was the most abundant with approximately 39% of individuals. Wood litter decomposition grouped with annual Hemiptera abundance, co-varying with soil epigeic fauna diversity and evenness per plot and against soil fertility variables. Leaf litter decomposition co-varied with the total epigeic fauna abundance and soil pH. We speculate that the specific need to decompose wood litter may be associated with a greater need for diversity than an abundance of soil epigeic fauna. Our work highlights the role of rainfall seasonality on soil biodiversity and physicochemistry, which is also tightly linked with litter production and decomposition. This study advances our understanding of the mechanisms governing nutrient cycling in savanna ecosystems on nutrient-impoverished soils, with implications for achieving sustainable conservation and restoration goals.

Leaf litter production and litter nutrient dynamics of invasive Acacia mearnsii and native tree species in riparian forests of the Fynbos biome, South Africa

Alien invasive Australian tree species are most prevalent in the Cape Floristic Region (CFR), a global biodiversity hotspot. The plants pose a serious threat as they have replaced indigenous riparian forest vegetation, including many native tree species such as Brabejum stellatifolium and Metrosideros angustifolia along many watercourses. Black wattle (Acacia mearnsii) is a leguminous nitrogen fixer which makes significant contributions to available nitrogen in its new habitats in the fynbos, which is generally low in nutrients. However, the magnitude and the timing of litter associated nutrient input into riparian forests and woodlands and adjacent aquatic environments are not known. In this study, we assessed patterns of leaf litterfall, nutrient return to soil and resorption (N and P) of A. mearnsii and two co-occurring native species in two perennial streams in the Mediterranean-type Fynbos biome of the CFR. Leaf litterfall of A. mearnsii in the riparian forests was significantly greater compared to native vegetation, with two peaks in litterfall, one in mid-autumn, and the other in mid-summer at both streams. In contrast, the native vegetation only dropped leaves in the summer month of December. Acacia mearnsii also returned substantially more nutrients (N and P) during the peak leaf litterfall period (December) than co-occurring native species. However, the co-occurring native species were more efficient in the resorption of nutrients (N and P), with average resorption higher than the global averages of 52% for N and 50% for P. In contrast, A. mearnsii was relatively inefficient in resorbing N (30% mean N resorption) but was more efficient in resorbing P (76% mean P resorption). In addition to fixing N, it is possible that the A. mearnsii stands rely on the return of nutrient-rich leaf litter to soils and through specialized root systems and root symbionts assisting reuse of nutrients. The results highlight the differences in the nutritional economy between native riparian forest species and invasive A. mearnsii. Our findings provide further insight into the success of invasive leguminous woody tree species in nutrient-poor Mediterranean riparian forests.

Soil carbon and nutrient stocks under Scots pine plantations in comparison to European beech forests: a paired-plot study across forests with different management history and precipitation regimes

BackgroundOrganic carbon stored in forest soils (SOC) represents an important element of the global C cycle. It is thought that the C storage capacity of the stable pool can be enhanced by increasing forest productivity, but empirical evidence in support of this assumption from forests differing in tree species and productivity, while stocking on similar substrate, is scarce.MethodsWe determined the stocks of SOC and macro-nutrients (nitrogen, phosphorus, calcium, potassium and magnesium) in nine paired European beech/Scots pine stands on similar Pleistocene sandy substrates across a precipitation gradient (560–820 mm∙yr− 1) in northern Germany and explored the influence of tree species, forest history, climate, and soil pH on SOC and nutrient pools.ResultsWhile the organic layer stored on average about 80% more C under pine than beech, the pools of SOC and total N in the total profile (organic layer plus mineral soil measured to 60 cm and extrapolated to 100 cm) were greater under pine by about 40% and 20%, respectively. This contrasts with a higher annual production of foliar litter and a much higher fine root biomass in beech stands, indicating that soil C sequestration is unrelated to the production of leaf litter and fine roots in these stands on Pleistocene sandy soils. The pools of available P and basic cations tended to be higher under beech. Neither precipitation nor temperature influenced the SOC pool, whereas tree species was a key driver. An extended data set (which included additional pine stands established more recently on former agricultural soil) revealed that, besides tree species identity, forest continuity is an important factor determining the SOC and nutrient pools of these stands.ConclusionWe conclude that tree species identity can exert a considerable influence on the stocks of SOC and macronutrients, which may be unrelated to productivity but closely linked to species-specific forest management histories, thus masking weaker climate and soil chemistry effects on pool sizes.

Assessment of Leaf Litter Production in Tropical Trees

Litter is the layer of detached dead plant material present on the surface of the soil. It plays an imperative part in the nutrient budgeting in agroforestry system. The quantum of litter produced varies with species and also seasons. Generally the litter production will be more during summer and less during monsoon times. Further the nature of the tree species like evergreen and deciduous will also influence litter production. In the present study, 10 tree species commonly found in farm lands were identified and selected from the experimental plot, which was located in Southern agro-climatic zone of Tamil Nadu and the soil type is alfisol with a pH of 6.0. The age of the trees was 10 years. The litter collection was done throughout the year on monthly basis and quantities produced were recorded. The data recorded were subjected to statistical analysis. The results revealed the following. Acacia auriculiformis produced a maximum leaf litter of 10.0 t/ha/year followed by Senna siamea. Summer season had more litter (3.55 kg/tree) followed by winter (1.54 kg/ha). A maximum mean monthly litter of 2.54 kg/tree was recorded in Tamarindus indica followed by Acacia mangium (0.76 kg/tree). Senna siamea and Gliricidia produced leaf litter throughout the year. Tamarind produced a maximum annual litter of 30.42 kg/tree followed by Acacia mangium (9.07 kg/tree).

Interaction of macroinvertebrates in leaf litter in forest ecosystems: a review

The leaf litter consists of vegetable fragments/waste (e.g., leaves, fruits, twigs) and animals. Acting on soil fertilization through its decomposition and fragmentation by abiotic factors (for example, bacteria, fungi, invertebrates, and vertebrates), helping in the process of nutrient cycling, becoming an alternative in the recovery of degraded areas. Its production varies according to the climatic conditions of the region, being the observation as greater leaf litter production in tropical and subtropical areas, as well as the semi-arid regions, where the plants in greater depth lose their leaves allowing a higher deposition of the biomass in the soil. The leaf litter still acts, as it applies to a diversity of animals that they use as a means to develop. Among the most representative animals are the Annelida (Oligochaeta), Myriapoda (Chilopoda and Diplopoda), Hexapoda (Diptera, Hemiptera, Orthoptera, Coleoptera, Blattodea, Isoptera, Hymenoptera, Lepidoptera, Isopoda, Thysanura), Cheliceriformes Araneae, Scorpiones, Pseudoscorpiones and Opiliones), Mollusca (Gastropoda). All these factors make the leaf litter, a source of nutrients rich in organic compounds that help improve soil fertility and provides the animals that live in it a universe of ecological niches that suit the needs of each species.

Which Agroforestry Practice Is Beneficial? A Comparative Assessment of the Traditional and the Improved Agroforestry Techniques in the Midhills of Nepal

Farmers are predominantly adopting two forms of agroforestry, traditional and improved practices, in the midhills of Nepal, but their efficacy on a comparative basis is poorly assessed, so farmers often confuse whether to continue the traditional practice or embrace the improved practice. We carried out a study in six villages of three districts, interviewed 210 farmers adopting each practice, organized six focus group discussions, and interacted with 24 key informants to compare agroforestry practices from income generation and forest conservation perspectives. An individual household adopting the improved practice annually generated 841.60 US$, which was more than two folds of the traditional practitioner. Similarly, the improved practitioner annually fulfilled 84% demand for forest products from the adopted agroforestry practice, whereas the traditional practitioner only fulfilled about 50%. The fodder, fuelwood, and timber productions were found to be significantly higher in the improved practice, whereas leaf litter production was found to be almost similar. The improved practitioners seemed to be self-sustained in forest products, where the traditional practitioners only satisfied half of their requirements from the agroforestry practice. The study concludes that the improved agroforestry practice is more beneficial compared to the traditional practice. Therefore, we suggest the traditional practitioners to modify their ongoing practice to enhance the contribution of agroforestry practice at the local level.

Leaf-litter production in human-modified Amazonian forests following the El Niño-mediated drought and fires of 2015–2016

Leaf-litter production is an essential part of the carbon cycle of tropical forests. In the Amazon, it is influenced by climate, presenting high levels during the driest months of the year. However, it is less established how extreme climatic events may impact leaf-litter production in the long term. Even more unclear is how litter production is affected by human-driven disturbances. Here we examine the effects of the 2015–16 El Niño drought and subsequent fires in the leaf-litter production of human-modified Amazonian forests, thus investigating the interactions of a climatic extreme with anthropogenic disturbances on this key process of the Amazonian carbon cycle. We sampled leaf litter from April 2015 until March 2019 across 20 plots located in the eastern Brazilian Amazon, in a total of 11,548 samples. Plots were distributed along a pre-El Niño gradient of human disturbance, including undisturbed, logged, logged-and-burned, and secondary forests. All plots were impacted by the extreme drought caused by the 2015–16 El Niño, and eight were also impacted by understory fires. We found a significant and non-linear relationship between precipitation and monthly leaf-litter production – above 300 mm of monthly precipitation, the production of leaf-litter becomes independent of rainfall. Surprisingly, this relationship was not influenced by pre-El Niño forest disturbance class. During the El Niño, leaf-litter production was higher, decreasing sharply in the following year, especially in El Niño-fire-affected forests. Between 2017 and 2019, all forests experienced a gradual increase in the production of leaf litter. However, the mechanisms behind this increase remain unclear and are likely different between forests affected only by the El Niño drought and those affected by both the drought and fires. Our results suggest that while leaf-litter production may be insensitive to past human disturbances, it is affected, in the short term, by extreme climatic events, especially in forests impacted by El Niño fires.

Litterfall guided soil nutrient return in Eucalyptus based agroforestry system

Here, the arrangement of litterfall and nutrient return to the soil by the seven-year-old plantations of Eucalyptus under different spacings established on sodic wastelands in northern India was determined. The litterfall was sorted into leaf wood and miscellaneous. Further, the seasonal variation of litterfall obtained under three different spacings was recorded. Maximum leaf litter production was observed in 3×3 m spacing followed by 6×1.5 m during the winter season. Whereas, the minimum leaf litter was recorded in 17×1×1 m spacing. Similarly, the maximum wood litter production was observed at the spacing of 3×3 m spacing in rainy season followed by 6×1.5 m.The weights of nutrients returned through annual litterfall in 3×3 spacing returned the highest amount of N (2.16 g/m2 year) followed by 6×1.5 and 17×1×1 spacing.. Whereas, two-year data of litterfall of E. tereticornis showed the 17×1×1 spacing returned the highest amount of P in next year through leaf litter followed by 6×1.5 and minimum 3×3 spacing. Overall, this study provides important information regarding the litterfall guided soil nutrient return to the soil under North Indian conditions.

Photosynthetic characteristics and leaf litter production of mangrove forests in Trang, southern Thailand

The aim of this study was to investigate the photosynthetic performance and litter production of planted (PLA) and natural (NAT) mangroves in Trang, southern Thailand. Relative chlorophyll content and other photosynthetic parameters, such as photosynthetic efficiency of Photosystem II (Phi2), yield of non-regulatory energy dissipation (PhiNO), yield of non-photochemical quenching (PhiNPQ) and quenching due to non-photochemical dissipation of absorbed light energy (NPQt), and litter fall production were determined and compared between two mangrove stands. Measurements of photosynthetic parameters were made using PhotosynQ to assess the health of the community structure in both stands. The assumption of this study, namely that there would be no significant difference in any photosynthetic parameter measured between the two stands, was confirmed using t-test with unequal variances confirmed (P &gt; 0.05 for all). Changes occurred quarterly and in sites with different species. In terms of litter production, significant differences were found according to stand (P &lt; 0.001), season (P &lt; 0.05) and site (Sikao, F3,129 = 4.357, P &lt; 0.01; Kantang, F3,190 = 3.243, P &lt; 0.01). PLA stands demonstrated similar photosynthetic characteristics to NAT stands. This study established the effects of land use changes on PLA mangroves (planted in an abandoned shrimp pond). The overall significance of the study is in highlighting the positive outcomes of mangrove restoration, particularly in degraded mangrove stands due to land use change.

PRECIPITATION DEFICITS AND HIGH TEMPERATURE INCREASE LEAF LITTERFALL IN OPEN RESTINGA VEGETATION, IN SOUTHERN BRAZIL

Climate is an important driver of litterfall along different ecosystems. However, little is known about how climate affects litter production in plant communities of Restinga. The aim of this study is to characterize the temporal variation in leaf litter production in an Open Clusia Formation in Restinga de Jurubatiba National Park, from 2001 to 2018, and assess how local variability in litter production reflects the local climatic conditions and its variability. We tested the hypothesis that monthly leaf litterfall increases in dry months and in drier and warmer than average months; we also evaluated if annual leaf litterfall increases in wetter and warmer years following leaf production patterns, that increases in these conditions. We found that litterfall peaks in the drier months. This pattern is consistent for many tropical ecosystems, even evergreen ecosystems, and may have evolved as a strategy that result in reduced water stress by plants, during drier and warmer periods, or may simply be a stress symptom. However, we also found that decreases in monthly rainfall and increases in monthly ∆Temperature (temperature observed minus estimated based on 1970-2000 interval) stimulate leaf litter production. Hot and warmer than average years also seem to stimulate leaf litterfall. It suggests that annual leaf litterfall and leaf production are less affected by precipitation regimes than variations in temperature (or radiation, which is directly related to temperature). It may result from the fact that Clusia hilariana, the dominant species in this ecosystem which accounts to 80 % of leaf litterfall, is a CAM photosynthesis species, a characteristic commonly associated with avoidance of water stress by plants. Although leaf litterfall seems to be predominantly driven by climate at annual scale, only 15 % of its variation was associated to climate at seasonal scale, suggesting that local factors control litterfall at lower temporal scales in Open Clusia Formation.

Temperature is a dominant driver of distinct annual seasonality of leaf litter production of equatorial tropical rain forests

Abstract Intra‐annual periodicity of canopy photosynthetic activity and leaf development has been documented in seasonal and weakly seasonal tropical forests in the Amazon and elsewhere. However, vegetative periodicity such as leaf flush and fall in apparently ‘aseasonal’ equatorial tropical forests has not been well documented. Moreover, causal drivers of the vegetative periodicity in those forests have not been identified largely because of the difficulty in performing manipulative experiments targeting whole forest ecosystem dynamics. Here we show a distinct annual seasonality in canopy dynamics using a Fourier analysis with a statistical significance test on the long‐term, fortnightly monitored dataset of leaf litterfall in nine evergreen tropical rain forests on Mount Kinabalu, Borneo. Statistically significant annual periodicity occurs across elevations and soil types in all years irrespective of the year‐to‐year climatic variability, suggesting that fluctuations in regional climate rather than local micro‐climatic, edaphic and/or biotic conditions cause the precise 1‐year periodicity. We examine climatic factors that have causative effects on the distinct 1‐year periodicity using the spectrum convergent cross mapping that we developed in the present study that can distinguish causal relationships from seasonality‐driven synchronization. According to the analysis, we find that mean daily air temperature is most strongly, causatively related to the 1‐year periodicity of leaf litterfall. However, knowledge on ecophysiolocial and molecular mechanisms underlying temperature‐control of tropical tree growth is limited and further studies are required to understand the detailed mechanisms. Synthesis. We suggest that intra‐annual temperature changes in association with the movement of the intertropical convergence zone cause the distinct annual vegetative periodicity. Because vegetative periodicity can be transmitted to the dynamics of higher trophic levels through a trophic cascade, interactions between vegetative periodicity and daily air temperature, not rainfall, would more strongly cause changes in the dynamics of equatorial tropical rain forests. Our results show that clear vegetative periodicity (i.e. annual seasonality) can be found in equatorial tropical rain forests under diverse local environments, and that air temperature is a more important factor than the other climate variables in the climate–forest ecosystem interactions.

Dynamics of leaf, flower and fruit abscission in avocado cv. Hass in Antioquia, Colombia

The amount of leaf litter produced by avocado trees cv. Hass is an important potential source of mineral resources, and quantifying its production and nature is crucial to understanding the cycling of nutrients. The main objective of this study was to quantify the production of leaf litter and fallen flowers and small fruits in avocado orchards at eight locations in three producing areas in the Department of Antioquia (west, southwest, and north). The highest leaf litter production occurred in southwest Antioquia, at Jardin (7.6 t ha-1 year-1); the east locations had similar leaf fall (4.03-3.4 t ha-1 year-1). The dry matter produced in the north was very similar in both locations. The dry matter was 2.8 t ha-1 year-1. Higher leaf litter was recorded in all locations during the driest periods. Approximately 80% of the fallen fruits had diameters less than 1 cm. The highest flower production and fall occurred in southwest Antioquia, followed by the northern region.

Produksi Serasah Musiman pada Berbagai Spesies Mangrove di Pesisir Kabupaten Muna Barat, Sulawesi Tenggara

Mangrove litter production is important in the displacement of organic matter from mangrove vegetation to water such as in the coast of West Muna Regency. However, one factor influencing it is the frequency of rainfall. This research, therefore, aims to determine the influence of the frequency of rainfall in mangrove ecosystem by obtaining data through the fractional wet weight. The results showed that the biomass fraction with the largest amount were Rhizophora mucronata, Rhizophora apiculata, and Sonneratia alba with of 31.59; 31.07; and 30.96%, respectively, while the lowest was Rhizophora stylosa, Bruguiera cylindrica, and Bruguiera gymnorrhiza with of 30.07; 30.10; and 31.95%, respectively. The species with the largest leaf litter production was Bruguiera cylindrica, with of 1.72 g.m-2.day-1 which occurred in April and the lowest was Rhizophora apiculata, 0.24 g.m-2.day-1 in August. The species with the largest leaf litter production was Bruguiera cylindrica, 1.96 g.m-2.day-1 which occurred in May and the lowest was Sonneratia alba, 0.29 g.m-2.day-1 in August. In addition, the species with the largest fruit litter production was Rhizophora apiculata, 1.76 g.m-2.day-1 in April and the lowest was Sonneratia alba, 0.32 g.m-2.day-1 in September. The total litter production was 18,75 g.m-2.day-1 consisted of 6,69 g.m2.day-1 leaf litter, 6,54 g.m-2.day-1 branch litter, and 5,52 g.m-2.day-1 fruit litter. The higher the frequency of the rain, the greater the litter production.&#x0D; &#x0D; Keywords: biomass fraction, seasonal litter production, West Muna Regency

Agroforestry systems of &lt;i&gt;Theobroma cacao&lt;/i&gt; L. affects soil and leaf litter quality

The objective of this study was to determine the effect of Agroforestry systems (AFS) and non-AFS of Theobroma cacao L. on soil and leaf litter quality, during rainy (RS) and dry (DS) seasons in a tropical zone. The treatments were T. cacao crop (CC), Yopo forestry (Anadenanthera peregrina L.) Speg. (YF), Acacia forestry (Acacia mangium Willd.) (AF), Agroforestry system of T. cacao + Yopo forestry (CYF), Agroforestry system of T. cacao + Acacia forestry (CAF), arranged in random design in the field. Leaf litter production was highest in CC (0.79 and 0.73 ton.ha-1) during RS and DS, respectively. CC and AFS improved soil fertility, less Mg in CC; AFS leaf litter quality, CAF in DS and CYF in both seasons, less B and S in DS. AFS can be a solution in tropical zones to solve the problems of low soil fertility.