Tree Leaf Litter Research Articles

Effects of different bulking agents on the maturity, enzymatic activity, and microbial community functional diversity of kitchen waste compost

ABSTRACTAerobic composting is an effective method for the disposal and utilization of kitchen waste. However, the addition of a bulking agent is necessary during kitchen waste composting because of its high moisture content and low C/N ratio. In order to select a suitable bulking agent, we investigated the influence of leaf litter (LL), sawdust (SD), and wheat straw (WS) on the enzymatic activity, microbial community functional diversity, and maturity indices during the kitchen waste composting process. The results showed that the addition of WS yielded the highest maturity (the C/N ratio decreased from 25 to 13, T value = 0.5, and germination index (GI) = 114.7%), whereas the compost containing SD as a bulking agent had the lowest maturity (GI = 32.4%). The maximum cellulase and urease activities were observed with the WS treatment on day 8, whereas the SD treatment had the lowest cellulase activity and the LL treatment had the lowest urease activity. The compost temperature and microbial activity (as the average well color development) showed that bulking the composts with SD prolonged the composting process. The diversity index based on the community-level physiological profile showed that the composts bulked with LL and WS had greater microbial community functional diversity compared with those bulked with SD. Thus, the maturity indexes and enzymatic activities suggest that WS is a suitable bulking agent for use in kitchen waste composting systems.

Allelopathic Effects of Homestead agroforestry Tree Leaf Litter on the Sprouting and Early Growth in Elephant Foot Yam (Amorphophallus paeniifolius)

The allelopathic effects of eight selected agroforestry tree litter on the sprouting and early growth of the understorey tuber crop, elephant foot yam (Amorphophallus paeniifolius) were examined during 2014-’15. Litter leachates at 2% concentration and litter mulch were used for the study and it was found that the effects of litter mulch were significant on sprouting and seedling growth while with the leachate, significant effects were recorded only on shoot growth and leaf production. The effects varied with species, tamarind and wild jack recorded maximum inhibition both as leachate and mulch. Litter of rubber, mango and jack showed stimulatory effects thus bringing to light their potential to be used as organic inputs in elephant foot yam cultivation.

Effect of N addition, moisture, and temperature on soil microbial respiration and microbial biomass in forest soil at different stages of litter decomposition

The objective of the present study was to investigate the interactive effects of nitrogen (N) addition, temperature, and moisture on soil microbial respiration, microbial biomass, and metabolic quotient (qCO2) at different decomposition stages of different tree leaf litters. A laboratory incubation experiment with and without litter addition was conducted for 80 days at two temperatures (15 and 25 °C), two wetting intensities (35 and 50 % water-filled porosity space (WFPS)) and two doses of N addition (0 and 4.5 g N m−2, as NH4NO3). The tree leaf litters included three types of broadleaf litters, a needle litter, and a mixed litter of them. Soil microbial respiration, microbial biomass, and qCO2 along with other soil properties were measured at two decomposition stages of tree leaf litters. The increase in soil cumulative carbon dioxide (CO2) flux and microbial biomass during the incubation depended on types of tree leaf litters, N addition, and hydrothermal conditions. Soil microbial biomass carbon (C) and N and qCO2 were significantly greater in all litter-amended than in non-amended soils. However, the difference in the qCO2 became smaller during the late period of incubation, especially at 25 °C. The interactive effect of temperature with soil moisture and N addition was significant for affecting the cumulative litter-derived CO2-C flux at the early and late stages of litter decomposition. Furthermore, the interactive effect of soil moisture and N addition was significant for affecting the cumulative CO2 flux at the late stage of litter decomposition but not early in the experiment. This present study indicated that the effects of addition of N and hydrothermal conditions on soil microbial respiration, qCO2, and concentrations of labile C and N depended on types of tree leaf litters and the development of litter decomposition. The results highlight the importance of N availability and hydrothermal conditions in interactively regulating soil microbial respiration and microbial C utilization during litter decomposition under forest ecosystems.

Effects of tree leaf litter, deer fecal pellets, and soil properties on growth of an introduced earthworm (Lumbricus terrestris): Implications for invasion dynamics

Invasive earthworm communities are expanding into previously earthworm-free forests of North America, producing profound ecosystem changes. Lumbricus terrestris is an invasive anecic earthworm that consumes a large portion of the detritus on the soil surface, eliminating forest floor organic horizons and reducing soil organic matter. Two mesocosm experiments were used to examine the individual and combined effects of litter and soil type on the growth of L. terrestris. The litter type experiment tested nine different food source treatments (7 tree leaf litters, deer fecal pellets, and a control), while the soil × litter type experiment used five different soil treatments (4 soil types and one soil type with A horizon material removed) in combination with four different food source treatments. We found that leaf litter type (p = 0.001) and soil type (p = 0.018) significantly affected earthworm growth rates, with growth rates on deer pellets similar to many high quality deciduous leaf litters. Of soil variables, exchangeable Ca (r2 = 0.99), sum base cations (r2 = 0.98), % organic matter (r2 = 0.93), %N (r2 = 0.89), %C (r2 = 0.87), and exchangeable Mg (r2 = 0.85) were all significant predictors of earthworm growth. Litter disappearance of all litter types was linearly related to growth, suggesting similar growth efficiency on different litter types. However, chemical properties, specifically foliar C:N and a linear combination of a suite of other chemical properties predicted growth, suggesting that consumption or gut passage rates were regulated by litter quality. This information about soil and litter characteristics that regulate L. terrestris growth should improve models of their distribution, spread and abundance.

Decomposition of leaf litter of some evergreen broadleaf trees in Korea

Litter decomposition is an important process in terrestrial ecosystem. However, studies on decomposition are rare, es- pecially in evergreen broadleaf trees. We collected the leaf litter of five evergreen broadleaf trees ( Daphniphyllum mac- ropodum, Dendropanax morbifera, Castanopsis cuspidata var. thunbergii, Machilus thunbergii and Quercus acuta), and carried out a decomposition experiment using the litterbag method in Ju-do, Wando-gun, Korea for 731 days from De- cember 25, 2011 to December 25, 2013. Among the five experimental tree species, C. cuspidata var. thunbergii distribution was limited in Jeju Island, and D. macropodum was distributed at the highest latitude at Mt. Baekyang (N 35°40'). About 2% of the initial litter mass of D. macropodum and D. morbifera remained, while 20.9% remained for C. cuspidata var. thunbergii, 30.4% for M. thunbergii, and 31.6% for Q. acuta. D. macropodum litter decayed four times faster (k = 2.02 yr -1 ) than the litter of Q. acuta (k = 0.58 yr -1 ). The decomposition of litter was positively influenced by thermal climate such as accumulated mean daily air temperature (year day index) and precipitation, as well as by physical characteristics such as thickness (R 2 =0.939, P = 0.007) and specific leaf area (SLA) ( R 2 = 0.964, P = 0.003). The characteristics of chemical composition such as lignin (R 2 = 0.939, P = 0.007) and water-soluble materials (R 2 = 0.898, P = 0.014) showed significant correlations with litter decomposition. However, the nutrients in litter showed complicated species-specific trends. The litter of D. macropodum and D. morbifera had fast decomposition despite their low nitrogen concentration and high C/N ratio. This means that the litter decomposition was more strongly affected by physical characteristics than chemical composition and nutrient content. On the other hand, the litter of Q. acuta which had the slowest decay rate had a high amount of N and low C/N ratio. Thus, the decomposition of Q. acuta litter was more affected by the P content of the litter than the N content, although all litter had similar physical characteristics.

Leaf litter resource quality induces morphological changes in wood frog (Lithobates sylvaticus) metamorphs.

For organisms that exhibit complex life cycles, resource conditions experienced by individuals before metamorphosis can strongly affect phenotypes later in life. Such resource-induced effects are known to arise from variation in resource quantity, yet little is known regarding effects stemming from variation in resource quality (e.g., chemistry). For larval anurans, we hypothesized that variation in resource quality will induce a gradient of effects on metamorph morphology. We conducted an outdoor mesocosm experiment in which we manipulated resource quality by rearing larval wood frogs (Lithobates sylvaticus) under 11 leaf litter treatments. The litter species represented plant species found in open- and closed-canopy wetlands and included many plant species of current conservation concern (e.g., green ash, common reed). Consistent with our hypothesis, we found a gradient of responses for nearly all mass-adjusted morphological dimensions. Hindlimb dimensions and gut mass were positively associated with litter nutrient content and decomposition rate. In contrast, forelimb length and head width were positively associated with concentrations of phenolic acids and dissolved organic carbon. Limb lengths and widths were positively related with the duration of larval period, and we discuss possible hormonal mechanisms underlying this relationship. There were very few, broad differences in morphological traits of metamorphs between open- and closed-canopy litter species or between litter and no-litter treatments. This suggests that the effects of litter on metamorph morphology are litter species-specific, indicating that the effects of changing plant community structure in and around wetlands will largely depend on plant species composition.

Impacts of earthworms on nitrogen acquisition from leaf litter by arbuscular mycorrhizal ash and ectomycorrhizal beech trees

Earthworms (EWs) and mycorrhizal fungi are key components of soil biota participating in N recycling from leaf litter. The extent to which their interactions impact leaf litter-derived N uptake by tree species colonized by different mycorrhizal types and the variation of these interactions with leaf litter quality is unknown. We used a greenhouse experiment to investigate the effects of EWs on plant acquisition of N from 15N enriched ash (Fraxinus excelsior) and beech (Fagus sylvatica) leaf litter. We employed arbuscular mycorrhizal (AM) ash and ectomycorrhizal (EM) beech trees. EW presence did not affect the overall root mycorrhizal colonization, but in the beech leaf litter treatment it caused a shift in the EM fungal community, favoring species with a ruderal life strategy at the expense of more specialized species able to degrade organic compounds. No differences in 15N capture were found between EM and AM plants. Generally, 2–7% of the N released from leaf litter was taken up by the plants. EWs uniformly increased plant acquisition of N from leaf litter. This effect was more pronounced in treatments with ash than in those with beech leaf litter, presumably because of higher degradability of ash than of beech litter. The results suggest that leaf litter quality dominates the impact of EWs on plant N acquisition from leaf litter while the mycorrhizal type is of minor importance.

Barriers to invasive infilling by Brachypodium sylvaticum in Pacific Northwest forests

The success of invasive plants is often dependent on continued natural and anthropogenic habitat perturbations but it is less clear whether invasive species are capable of infiltrating undisturbed plant communities (range infilling). We studied the ecology of Brachypodium sylvaticum (slender false brome), a Eurasian bunchgrass that forms dense and expansive monocultures in forests of Oregon’s Willamette Valley with the objective of assessing its potential to infill undisturbed forests near the edge of its expanding range. Observations suggest that B. sylvaticum may be associated with sites that have a history of disturbance, but infestations appear to be spreading in forest understory habitats. We assessed the effects of leaf litter depth and texture (proportions of coniferous and deciduous litter) on seedling recruitment in the field and in a controlled experiment. Coniferous litter facilitated the establishment and growth while the presence of deciduous litter severely reduced B. sylvaticum recruitment. Survival and growth of established B. sylvaticum seedlings was highest in the coniferous litter. Leaf litter treatments contributed to the retention of soil moisture and seedlings had increased biomass and more tillering with deeper litter. Field surveys partially corroborated these results; recruitment occurs at the edge of existing B. sylvaticum populations where leaf litter depth is moderate, but B. sylvaticum is absent from regions of the understory characterized by deeper and less dense leaf litter. These results suggest that B. sylvaticum has the potential to invade native understory communities, but the progress of invasion will depend on the frequency and intensity of perturbations of the accumulated leaf litter.

Decomposition of Subtropical Fruit Tree Leaf Litter at Nelspruit, South Africa

There is limited information about the decomposition of leaf litter from subtropical fruit trees despite their potential for managing soil fertility. The aim of this study was to quantify the effect of quality on decomposition and nutrient-release patterns from leaf litter of avocado, litchi, and mango trees in South Africa. The litterbag technique was used for investigation. The decomposition results over 2 years indicated significant differences in mass loss among the tree species with low rapid loss for litchi (57.3 percent). The annual decomposition rate constant (k) decreased in the order mango (0.82) > avocado (0.76) > litchi (0.69). The concentrations of phosphorus, potassium, manganese, and polyphenols in all species decreased while nitrogen, sulfur, and calcium concentrations increased with time. The nutrient-release pattern of the leaf litter from the three species varied considerably due to different quality characteristics. This had an influence on litter decomposition and thus its management.

Effects of litter type, origin of isolate, and temperature on decomposition of leaf litter by macrofungi

The dependence of hyphal growth and litter decomposition on litter type and incubation temperature used as substratum were compared for litter-decomposing macrofungi originating from subtropical (ST), cool temperate (CT), and subalpine forests (SA) in Japan. In the first series of pure culture decomposition tests using a total of 39 litter types as substrata inoculated with six fungal isolates from the three climatic regions, the fungal decomposition of litter was negatively affected by the content of acid-unhydrolyzable residues (AUR) or extractives and positively by N content in the litter. Secondly, cross-inoculation tests were performed to examine the mass loss of leaf litter of broad-leaved trees from ST, CT, and SA, each inoculated with three Mycena species from the three climates and incubated at seven temperatures between 5 and 35 °C. Fungal isolate, litter type, incubation temperature, and their interactions significantly affected the mass loss of litter during the incubation. The greatest values of mass loss were found at 20 or 25 °C, and were generally consistent with the optimum temperatures of colony diameter growth rate of these isolates. Isolates from cooler regions were more sensitive to higher temperature than isolates from warmer regions. The decomposition of recalcitrant compounds (as acid-unhydrolyzable residues, AUR) by Mycena sp. from ST was also affected by litter type and incubation temperature, but the degree of selective decomposition of AUR relative to other components, such as cellulose, was insensitive to the range of temperature tested.

Urban-induced changes in tree leaf litter accelerate decomposition

The role of urban areas in the global carbon cycle has so far not been studied conclusively. Locally, urbanization might affect decomposition within urban boundaries. So far, only few studies have examined the effects of the level of urbanization on decomposition. This study addresses the influence of the level of urbanization on decomposition processes. It explores whether potential influences are exerted through leaf litter quality alterations or through direct effects of decomposition site’s level of urbanization. Leaf litter of five different tree species was sampled at urban and periurban sites. Decomposition of this litter was analyzed in three different experiments: a climate chamber incubation, a reciprocal litterbag transplant at urban and periurban sites, and a common garden litterbag transplant. Decomposition site’s level of urbanization did not show a significant effect. However, in all species, when significant differences were observed, leaf litter of urban origin decomposed significantly faster than leaf litter of periurban origin. This effect was observed in all three experiments. In the reciprocal litter transplant experiment, 62% ± 3% mass loss in litter of urban origin compared to 53% ± 3% in litter of periurban origin was observed. The difference was not as pronounced in the other two experiments, with 94% ± 1% mass loss of litter originating in urban habitats compared to 92% ± 1% mass loss of litter originating in periurban habitats in the common garden experiment and 225 ± 13 mg CO2 released from litter originating in urban habitats compared to 200 ± 13 mg CO2 released from litter originating in periurban habitats in the climate chamber incubation. We conclude that the level of urbanization affects decomposition indirectly through alterations in leaf litter quality even over short urban to periurban distances.

Potentiality of Organic Rice Production Fertilized with Different Agroforestry Tree Leaf Litter in Northern Bangladesh

Potentiality of Organic Rice Production Fertilized with Different Agroforestry Tree Leaf Litter in Northern Bangladesh

Tree Growth, Litter Fall And Leaf Litter Decomposition OfCasuraina equisetifoliaBase Agri-Silviculture System

Tree growth, litter fall and leaf litter decomposition, nutrient return thought leaf litter and litter decomposition were 12 year old Csuraina equisetifolia plantation. The Tree growth under agri-silvicultural system at the beginning of experiment the observations recorded with respect to certain growth parameters of Casuarina equisetifolia have been shown in Table 1 2012–2013. The maximum tree height (14.59 m) found in tree no 4; Dbh (26.22 cm) and canopy width (4.18 m) were recorded in the same tree number 3. Whereas the maximum canopy length (4.32 m) was found in the tree number 3. In the next year 2013–2014 the observations recorded with respect to certain growth parameters at the end of experiment of Casuarina equisetifolia have been shown in Table 2. and the maximum tree height (17.98 m) found in tree no 2; Dbh (28.92 cm) and canopy width (7.04 m) were recorded in the same tree number 3. Whereas the maximum canopy length (7.61 m) was found in the tree number 3. The maximum litter from litter trap was recorded in (68.33 g) month of February during 2012–2013 and the minimum litter from litter traps was found in (27.98 g) month of September during the year 2013–2014.

美洲黑杨凋落叶分解初期对小白菜生长的影响

A pot experiment was conducted to study the effects of secondary metabolites released by decomposing Populus deltoides leaf litter on the growth and physiology of Brassica chinensis.In the main test four leaf litter application levels was set as 0,30,60 and 90 g / pot(respectively denoted as CK,L30,L60 and L90).Meanwhile,in order to test whether the physical form of the leaf litter could obviously influence the soil aeration,water permeability and even the growth of B.chinensis,the parallel blank test was performed with the steamed leaf litter,and the design of the test was set as same as the main test,namely 0,30,60 and 90 g / pot steamed leaf litter treatments(denoted as Z30,Z60 and Z90).Each pot contained 7 kg soil mixed with P.deltoides leaf litter and then sowed the seeds of B.chinensis.The height and physiological indices of B.chinensis were determined on 50 th,80thd after sowing.The results showed that:1) The height and fresh weight of B.chinensis with high leaf litter addition(L90) of P.deltoides to the soil was significantly inhibited on 50 thd,afterwards,the growth gradually resumed to normal on 80 thd,while the height and fresh weight of B.chinensis in the other two treatments were markedly promoted consistently during the experimental period; 2) After 50 days of sowing,the net photosynthetic rate(Pn) of B.chinensis was largely improved under low(L30) and medium(L60) addition of leaf litterrelative to CK.As time went by,there were no obvious differences between all treatments and CK on 80 thd.The variation trends of pigment contents on 50 thand 80thday were substantially the same,both slightly lower than CK,yet,Chl a / b almost remained unchanged for all the time; 3) The activity of Superoxidedismutase(SOD) did not change apparently in low and medium addition of leaf litter,but increased in high addition from beginning to the end in this experiment; 4) The content of Malondialdehyde(MDA) on 50 thand 80thday did not show any conspicuous differences whether there was leaf litter in soil or not,and no matter how much leaf litter was added to the soil within the amount range of litter designed in this experiment.In summary,the impacts that different amount of P.deltoides leaf litter militated on B.chinensis illustrated that:low and medium amount treatments of P.deltoides leaf litter mixed in soil stimulated the growth of B.chinensis,on the contrary high amount inhibited the growth.Besides,the result of parallel blank test showed that there was no evident disparity in regard to the growth and physiological indexes of B.chinensis among the steamed leaf litter treatments.On the whole,low and medium addition of P.deltoides leaf litter to the soil was absolutely conducive to the growth and physiological metabolism of B.chinensis,however,the suppression of allelopathic effect was remarkable with high addition of leaf litter in its initial decomposition stage.

Methane-derived carbon in the benthic food web in stream impoundments.

Methane gas (CH4) has been identified as an important alternative source of carbon and energy in some freshwater food webs. CH4 is oxidized by methane oxidizing bacteria (MOB), and subsequently utilized by chironomid larvae, which may exhibit low δ13C values. This has been shown for chironomid larvae collected from lakes, streams and backwater pools. However, the relationship between CH4 concentrations and δ13C values of chironomid larvae for in-stream impoundments is unknown. CH4 concentrations were measured in eleven in-stream impoundments located in the Queich River catchment area, South-western Germany. Furthermore, the δ13C values of two subfamilies of chironomid larvae (i.e. Chironomini and Tanypodinae) were determined and correlated with CH4 concentrations. Chironomini larvae had lower mean δ13C values (−29.2 to −25.5 ‰), than Tanypodinae larvae (−26.9 to −25.3 ‰). No significant relationships were established between CH4 concentrations and δ13C values of chironomids (p>0.05). Mean δ13C values of chironomid larvae (mean: −26.8‰, range: −29.2‰ to −25.3‰) were similar to those of sedimentary organic matter (SOM) (mean: −28.4‰, range: −29.3‰ to −27.1‰) and tree leaf litter (mean: −29.8 ‰, range: −30.5‰ to −29.1‰). We suggest that CH4 concentration has limited influence on the benthic food web in stream impoundments.

Leaves and litterbugs: how litter quality affects amphipod life-history and sexually selected traits

Resources that cross ecosystem boundaries (subsidies) are common in nature, but we have little knowledge of how such resources affect individual traits and, consequently, ecological interactions. In wetlands, leaf litter is an important resource subsidy that regulates ecological processes including the production of consumer biomass. However, litter quality is highly variable and depends on local plant species diversity. Many aquatic consumers are highly nutrient limited, so differences in nutrients and other chemical components in litter are likely to affect numerous individual traits of consumers including life-history and sexually selected traits. We tested whether the species of tree leaf litter consumed by freshwater amphipods affected survival, growth, and development of sexually selected traits. Amphipods had higher survival, attained larger body sizes, and had larger male sexual traits when reared on litter that was relatively nutritious and low in plant secondary and structural compounds. Such widespread trait changes suggest that changing forest composition could have substantial effects on wetland ecology and the evolution of sexual traits over ecological time scales.

Increasing Red Maple Leaf Litter Alters Decomposition Rates and Nitrogen Cycling in Historically Oak-Dominated Forests of the Eastern U.S.

Without canopy-opening fire disturbances, shade-tolerant, fire-sensitive species like red maple (Acer rubrum L.) proliferate in many historically oak-dominated forests of the eastern U.S. Here, we evaluate potential implications of increased red maple dominance in upland oak forests of Kentucky on rates of leaf litter decomposition and nitrogen (N) cycling. Over 5 years, we evaluated mass loss of leaf litter and changes in total N and carbon (C) within six leaf litter treatments comprised of scarlet oak, chestnut oak, and red maple, and three mixed treatments of increasing red maple contribution to the leaf litter pool (25, 50, and 75% red maple). Over a 1.5-year period, we conducted a plot-level leaf litter manipulation study using the same treatments plus a control and assessed changes in net nitrification, ammonification, and N mineralization within leaf litter and upper (0–5 cm depth) mineral soil horizons. Red maple leaf litter contained more “fast” decomposing material and initially lost mass faster than either oak species. All litter treatments immobilized N during initial stages of decomposition, but the degree of immobilization decreased with decreasing red maple contribution. The leaf litter plot-level experiment confirmed slower N mineralization rates for red maple only plots compared to chestnut oak plots. As red maple increases, initial leaf litter decomposition rates will increase, leading to lower fuel loads and more N immobilization from the surrounding environment. These changes may reduce forest flammability and resource availability and promote red maple expansion and thereby the “mesophication” of eastern forests of the U.S.

Metal(loid) allocation and nutrient retranslocation in Pinus halepensis trees growing on semiarid mine tailings

The goal of this study was to evaluate internal metal(loid) cycling and the risk of metal(loid) accumulation in litter from Pinus halepensis trees growing at a mine tailing disposal site in semiarid Southeast Spain. Internal nutrient retranslocation was also evaluated in order to gain insight into the ability of pine trees to cope with the low-fertility soil conditions at the tailings. We measured metal(loid) concentrations in the foliage (young and old needles), woody stems and fresh leaf litter of pine trees growing on tailings. The nutrient status and stable isotope composition of pine foliage (δ13C, δ15N, δ18O as indicators of photosynthesis and water use efficiency) were also analyzed. Tailing soil properties in vegetation patches and in adjacent bare soil patches were characterized as well. Significant amounts of metal(loid)s such us Cd, Cu, Pb and Sb were immobilized in the woody stems of Pinus halepensis trees growing on tailings. Leaf litterfall showed high concentrations of As, Cd, Sb, Pb and Zn, which thereby return to the soil. However, water extractable metal(loid) concentrations in tailing soils were similar between vegetation patches (mineral soil under the litter layer) and bare soil patches. The pines growing on mine tailings showed very low foliar P concentrations in all leaf age classes, which suggests severe P deficiency. Young (current year) needles showed lower accumulation of metal(loid)s, higher nutrient concentrations (P and K), and higher water use efficiency (as indicated by and δ13C and δ18O data) than older needles. Substantial nutrient resorption occurred before leaf litterfall, with 46% retranslocation efficiency for P and 89% for K. In conclusion, phytostabilization of semiarid mine tailings with Pinus halepensis is feasible but would require careful monitoring of the trace elements released from litterfall, in order to assess the long term risk of metal(loid) transfer to the food chain.

What potential is there for regeneration of native species from the soil seed bank in Coast Tea Tree‐dominated scrub?

SummaryShrub encroachment generally causes the loss of native species in herbaceous‐dominated communities. The ability of the original ecosystem to return to its pre‐encroachment state (i.e. its ecological resilience) will be partially contingent on the capacity of these species to regenerate from soil‐stored seed. Coast Tea Tree (Leptospermum laevigatum) has formed a dense scrub in many areas previously dominated by grassy woodland, and hence, managers need guidance about the effectiveness of strategies designed to recover the pre‐encroachment vegetation. In this context, we ask: what is the potential of species stored in the soil seed bank to return following Tea Tree removal? A germination experiment was undertaken using soil collected from dense stands of Tea Tree that had been long established. Heat/smoke was applied to soils to simulate the effects of a fire on the soil seed bank, while leaf litter treatments were used to mimic both undisturbed stands and stands where shrubs have been slashed where litter creates a physical barrier to emergence. We found the soil seed bank was dominated by exotic forbs (83% of all germinants) and contained few grasses. Heat and smoke decreased total species density but increased species diversity through the suppression of common exotics. Our data suggest that slashing would result in germination being dominated by exotic flora, but using fire would likely reduce that dominance. However, we conclude that recovery by much of the original flora after site occupation by Coast Tea Tree may be contingent on mechanisms other than soil‐stored seeds.

The biodiversity of Dictyostelid cellular slime molds in rubber tree leaf litter in Southern Thailand

The biodiversity of Dictyostelid cellular slime molds in rubber tree leaf litter in Southern Thailand