Canopy Litter Research Articles

Responses of nitrogen and phosphorus resorption of understory plants to microscale soil nutrient hetero-geneity in Chinese fir plantation.

We compared the interspecific differences in leaf nutrient resorption of two dominant understory species (Lophatherum gracile and Oplimenus unulatifolius), and analyzed the correlations between the intraspecific efficiency of leaf nutrient resorption and nutrient properties of soil and leaves in Chinese fir plantation. The results showed high soil nutrient heterogeneity in Chinese fir plantation. Soil inorganic nitrogen content and available phosphorus content varied from 8.58 to 65.29 mg·kg-1 and from 2.43 to 15.20 mg·kg-1 in the Chinese fir plantation, respectively. The soil inorganic nitrogen content in O. undulatifolius community was 1.4 times higher than that in L. gra-cile community, but there was no significant difference in soil available phosphorus content between the two communities. Both leaf nitrogen and phosphorus resorption efficiency of O. unulatifolius was significantly lower than that of L. gracile under the three measurement bases of leaf dry weight, leaf area, and lignin content. Resorption efficiency in L. gracile community expressed on leaf dry weight was lower than that expressed on leaf area and lignin content, while resorption efficiency expressed on leaf area was the lowest in O. unulatifolius community. The intraspecific resorption efficiency was significantly correlated with leaf nutrient contents, but was less correlated with soil nutrient content, and only the nitrogen resorption efficiency of L. gracile had significant positive correlation with soil inorganic nitrogen content. The results indicated that there was significant difference in the leaf nutrient resorption efficiency between the two understory species. Soil nutrient heterogeneity exerted a weak effect on the intraspecific nutrient resorption, which might be attributed to high soil nutrient availability and potential disturbance from canopy litter in Chinese fir plantation.

Dynamics of Non-Structural Carbohydrates Release in Chinese Fir Topsoil and Canopy Litter at Different Altitudes.

Non-structural carbohydrates (NSCs) are labile components in forest litter that can be released quickly at the early stage of litter decomposition and accelerate the metabolic turnover of soil microorganisms, which is essential for the formation of forest soil organic matter. Therefore, understanding the NSCs response mechanisms to forest litter at different altitudes is critical for understanding nutrient cycling in the forest soil under climate change conditions. In this study, we used the net bag decomposition method to observe the dynamics of NSCs release in Chinese fir topsoil and canopy litter at four altitudes for 360 days based on the climatic zone characteristics distributed vertically along the elevation of Wuyi Mountain. The release of NSCs in Chinese fir litter rise gradually with height increases during the decomposition. The difference of the cumulative release percentage of soluble sugar between different altitudes is more significant than that of starch. The response of the NSC content in different treatment groups at four altitudes are different. The release of NSCs in the leaf canopy litter is higher than that in the leaf topsoil litter. On the contrary, the release of NSCs in the mixture of leaf and twig topsoil litter is higher than that in the mixture of leaf and twig canopy litter. Taken together, this study is of great significance for a comprehensive understanding of the effect of climate change on NSCs during the decomposition of Chinese fir litter.

Litterfall dynamics in Scots pine (Pinus sylvestris), Norway spruce (Picea abies) and birch (Betula) stands in Estonia

Canopy litterfall represents an essential aboveground flux in every forest ecosystem, affecting soil carbon and nutrient dynamics as well as soil fertility. However, despite the important role of the canopy litter flux in ecosysteḿs functioning and carbon sequestration, litterfall dynamics is still poorly studied in hemiboreal forests. The main aim of the current study was to estimate average annual litter fluxes in Scots pine, Norway spruce and birch (Betula pendula and Betula pubescens) stands, as well as to compile regional litter models for estimating the annual litter flux. The annual litter flux from a total of 33 pine, 15 spruce and 21 birch stands, with 85, 43 and 53 datapoints, respectively, was included in the study.Although the annual litter flux depended on site quality index and stand age, no significant relationship was established between stand basal area and litter flux. Average annual canopy litterfall was similar for the studied tree species, being 3.24 ± 0.14 for pine, 3.62 ± 0.16 for spruce and 3.22 ± 0.07 t ha−1 yr−1 for birch across the stands of different ages. For all studied tree species, the relative proportion of needles or leaves in the total annual litter flux declined with stand age, due to the increased share of twigs and other fractions in the litter of older stands. The developed models of the litter flux allow to estimate the annual litter production of the canopy for the studied tree species on the basis of site quality index and stand age.

Spatiotemporal distribution of canopy litter and nutrient resorption in a chronosequence of different development stages of Cunninghamia lanceolata in southeast China

Canopy litter is an important component of coarse woody debris (CWD), which affects nutrient and carbon cycling in forest ecosystems. For marcescent plant species (characterized by dead branches and leaves remaining in the canopy for several years before abscission), nutrient resorption from senescing leaves is an important nutrient conservation strategy. However, investigating the ecological function of canopy litter is challenging due to its limited accessibility and also the heterogeneous canopy microclimate in terms of light transmission, temperature and moisture. We studied the spatiotemporal distribution of canopy litter mass and seasonal dynamics of leaf nutrients and nutrient resorption during senescence in the canopy along a chronosequence of Chinese fir [Cunninghamia lanceolata (Lamb.) Hook] plantations in southeast China. The dry mass weight of dead branches and dead leaves in the canopy significantly increased with stand stage (14.6, 14.2, and 17.4 t ha−1 for young, middle-aged, and mature stands respectively), accounting for high proportions of total aboveground litter of 85.7%, 79.1% and 80.0%, respectively, along with annual litterfall production (2.44, 3.75, and 4.34 t ha−1, respectively). The canopy height distribution of dead branches and leaves also increased with stand age, ranging from 0 to 4 m in young stands, 3–8 m in middle-aged stands, to 4–10 m in mature stands. The seasonal pattern of canopy litter mass was the inverse of litterfall production: canopy litter mass peaked, while litterfall production was lowest in winter. Mean N, P, K, and Mg nutrient resorption efficiencies across stands at each stage were 53.8–58.9%, 64.0–68.9%, 85.0–90.2%, and 46.5–56.6%, respectively, while Ca was not retranslocated from senescing leaves. In summary, Chinese fir plantations retain large amounts of dead branches and leaves in the canopy from which at least ~50% of the nutrients N, P, K and Mg are recycled, representing an important nutrient conservation strategy that has evolved to adapt to nutrient-limited habitats. Canopy litter therefore plays an important role in these forest plantation ecosystems and should be protected instead of being removed from the canopy to the forest floor.

The potential for mass ratio and trait divergence effects to explain idiosyncratic impacts of non‐native invasive plants on carbon mineralization of decomposing leaf litter

Abstract Invasive plant effects on litter decomposition tend to be idiosyncratic among species and ecosystems, which may arise from variation in the invader’s relative abundance (mass ratio effect), from its relative functional difference to other species (trait divergence effect) and/or from species’ litter mixing that causes non‐additive decomposition rates relative to single‐species decomposition. We use experimental microcosms to quantify the potential for mass ratio and trait divergence to explain effects of invasive litters on carbon mineralization rates of decomposing litter mixtures and to generate non‐additive dynamics in two distinct forest litter types. The relative strength and direction of the mass ratio and trait divergence effects on carbon mineralization values were moderated by interactions between each effect and the canopy litter mixture. In both maple–poplar and oak–hickory litter mixtures, we found that the strength of the trait divergence effect increased with increasing proportions (mass ratio) of understorey litter in the litter mixtures, suggesting that interactions between these two mechanisms are important for moderating the influence of understorey invasions. Similarly, the addition of understorey litter always caused synergistic, non‐additive impacts on carbon mineralization, increasing carbon mineralization on average by 34%. For both litter mixtures, non‐additivity increased with increasing trait divergence between understorey and canopy litter. Our findings show the potential for pronounced context‐dependency in the impact of non‐native invasive species that arise via multiple mechanism and their interactions. As such, they suggest the necessity of accounting for frequently theorized but infrequently tested mechanisms relating to mass ratio and trait divergence. Accounting should improve understanding of when mass ratio and trait divergence affect ecosystem process rates, and hence build confidence in mechanistic projections of invader impacts. A plain language summary is available for this article.

Tuart (Eucalyptus gomphocephala) decline is not associated with other vegetation structure and composition changes

Tree decline affects forests and woodlands on most continents. The loss of canopy species from these landscapes has marked impacts on the surrounding environment. Understanding the consequences of tree mortality on vegetation structure and composition will contribute to developing management strategies for these ecosystems. The tuart (Eucalyptus gomphocephala), once the dominant tree species on the coastal plain in southwest Western Australia, has been cleared extensively and today occurs over less than a third of its former range. Compounding the effects of this clearing, dramatic declines in tree health over the past two decades has been recorded. We examined whether E. gomphocephala decline is reflected in changes to overall vegetation structure and composition. Using Landsat Thematic Mapper satellite data, we identified 12 sites with stable or improving vegetation vigour over the previous 15 years (‘healthy’ sites) and 12 sites with declining vegetation vigour over this time (‘declining’ sites). Health of E. gomphocephala trees, as well as litter, vegetation structure and vegetation composition were compared across these sites. Four health measures indicated that E. gomphocephala trees from healthy and declining sites were statistically distinguishable (p < 0.001). Trees at declining sites showed marked epicormic growth (up to 96% of canopy), evidence of crown dieback, reduced crown density and increased foliage transparency. The canopy changes were reflected in marked reduction in leaf litter for declining sites (p = 0.024). Despite the changes in E. gomphocephala canopy and leaf litter, however, there were no significant differences in vegetation community composition, relative vegetation cover for five height strata, vegetation structural and compositional diversity, presence of coarse woody debris, or overall canopy cover. There were also no differences in soil chemistry between the healthy and declining sites. The agent of tuart decline therefore appears to be specific to Eucalyptus gomphocephala at these sites, or alternatively the changes to other plant species have been too subtle to detect at this stage.

Myxomycetes associated with canopy organic matter in temperate rainforests of southern New Zealand

The dead plant material (canopy organic matter) associated with the mats of vascular plants and bryophytes found on tree branches in temperate rainforests along the southwestern coast of New Zealand was investigated for the presence of myxomycetes (plasmodial slime molds or myxogastrids). Samples of both the superficial litter layer (canopy litter) on the surface of the mat and the humus-like layer (canopy soil) beneath the mat were collected and used to prepare a series of moist chamber cultures. Canopy soil yielded more positive cultures (57%) but only three species of myxomycetes, whereas eight species were recovered from canopy litter (40% positive cultures). The higher percentage of positive cultures for canopy soil was the result of the appearance of plasmodia that could not be induced to form fruiting bodies. In contrast, fruiting bodies represented 67% of the positive cultures recorded from canopy litter.

Changes in the chemical compositions of leaf litter in the canopy of a Japanese cedar plantation

ABSTRACTCanopy leaf litter is typically unevenly distributed due to interception by branches and epiphytes and/or due to attachment to branches and tree trunks. Japanese cedar (Cryptomeria japonica) trees hold a large amount of canopy litter that stays attached to foliage and branches for several years before litterfall. Litter retention in the canopy is predicted to affect the chemical composition of litterfall and throughfall. We analyzed the chemical compositions of water-soluble materials washed from the leaves and those of the leaf residues with different leaf litter ages to clarify the effect of leaf-litter retention in the canopy of Japanese cedar trees. Chemical components of the leaf litter after the washing procedure show temporal changes in total carbon, total nitrogen, and carbon/nitrogen ratio just after senescence and prior to litterfall. Higher inorganic ion concentrations in soluble materials from old dead leaves (ODL) dead for more than 2 years suggest the importance of ODL in leaching and catching chemical components in the canopy. Our results show that Japanese cedar canopies retain the various qualities of leaf litter, which are produced by senescence, leaching, and catching dry deposition, and that a large amount of dissolved components leach from dead leaves that are still attached to the canopy.

Comparison of the species richness and abundance of Cerambycidae (Coleoptera) and Scolytinae (Coleoptera: Curculionidae) captured in aerial malaise traps with and without a bottom collector

AbstractMethods for detection and monitoring invasive insect species are continually being refined and developed. Detecting invasive pests early can improve chances of eradication or management of populations. Aerial malaise traps are successfully used in monitoring for insects such as longhorned beetles (Coleoptera: Cerambycidae) and bark and ambrosia beetles (Coleoptera: Curculionidae: Scolytinae). These traps have both a top and bottom collecting cup. The bottom portion of these traps leading to the collection cup collects canopy litter at a high rate, greatly increasing time required to sort through and possibly affecting the diversity and abundance of insects captured. Traps with top and bottom collecting cups were compared with traps with only top collecting cups to determine the effect on species richness and abundance of cerambycids and scolytines. There was no significant difference in species richness and abundance of cerambycids, and abundance of scolytines, however species richness of scolytines was significantly higher in top/bottom traps. We conclude that removing the bottoms from aerial malaise traps would benefit monitoring programmes that use this type of trap in combination with funnel traps, albeit with the potential loss of information on scolytine richness.

SWCF of Forest in Three-Gorges of Yangtze River

In Qinjiagou watershed of Three-Gorge of Yangtze River, 18 indices were selected from canopy layer, litter layer, soil layer and topography to evaluate the soil and water conservation capacities of four common plantation types by ideal point method. Results indicated that the broadleaf plantation of robur (Lithocrpus glabra) and Chinese gugertree (Schima superba) (LS) has the biggest soil and water conservation capacity. The rank of three other plantation types from big to small is the mixed broadleaf plantation of sweetgum (Liguidambar formosana), Chinese gugertree and camphor tree (Cinnamomum camphora) (LSC), the mixed broadleaf-conifer plantation of Chinese fir (Cunninghamia lanceolata), Masson pine (Pinus massoniana) and Chinese gugertree (CPS), and the mixed Pine plantation of Chinese fir and Masson pine (CP). Under the same climate and topographical condition, the broadleaf plantation has better soil and water conservation capacity than the conifer plantation. Sensitivity analysis showed that the three most sensitive indices are soil non-capillary porosity, soil aggregation, and soil initial infiltration rate. The litter amount and soil properties are the most important indicators of soil and water conservation capacity of plantations. Therefore, suitable measurements such as deep tillage should be taken to improve the properties of soil under different plantations.

The body-size distribution of arboreal collembolans in relation to the vertical structure of a Japanese cedar plantation

Collembolans are among the most abundant microarthropods in the aboveground parts of forest ecosystems, but little is known about their life-history traits compared with those of the soil-dwelling collembolans. The life-history traits of arboreal collembolans, as well as their abundances, are expected to be influenced by the vertical structure of a forest. We analyzed the body-size distributions of dominant arboreal species in relation to the vertical structure of the forest. The small individuals of the three arboreal species that inhabit both the canopy and soil litter (Xenylla brevispina, Tomocerus cuspidatus, and Sphyrotheca multifasciata) appeared continuously from spring to autumn in the soil litter, whereas those in the canopy litter were found during a particular period, only in July. These individuals tended to be larger in the canopy litter than in the soil litter, and in particular, T. cuspidatus grew to become significantly larger in the canopy. The mean body size of the most abundant migrating species (X. brevispina) increased gradually from the soil to the upper canopy, whereas strict arboreal species (Entomobrya sp.) had no significant trend in the relationship between body size and the height above ground level. We concluded that the life-history traits of arboreal collembolans were influenced by the vertical structure of the forest.

A new psychodid species from Saban tank bromeliads

A new species of Neotropical Psychodidae, Alepia apexalba sp. nov., is described from dry-forest tank bromeliads in Saba, Netherlands Antilles. Larvae, pupae and adults are described and figured. It is possible to relate larvae and adults because the latter were reared from pupae collected from the bromeliads (Tillandsia utriculata) that also contained larvae. Bromeliads are adapted to intercept canopy litter and throughfall water, and decaying litter is washed into and retained by the leaf bases. It is from this aquatic habitat that the larvae and pupae were collected.

Fine litter accumulation in Central Amazonian Tropical Rainforest canopy

Fine litter dynamics within the canopy differ from litter dynamics on the forest floor for reasons such as differences in microclimate, substrate, disturbance level, stratum influence and decomposition rates. This study is the first attempt to quantify the fine litter accumulated in the canopy of Central Amazonian forests. We compared the canopy litter accumulation to fine litter-layer on forest floor and to other forests and also investigated which were the mostly accumulated litter omponents. We found that Central Amazonian Rainforest intercepts greater fine litter in the canopy (294 g.m-2) compared to other forest formations with higher winds speed as in a Costa Rican Cloud Forest (170 g.m-2). The mean canopy fine litter accumulated at the end of the dry season was less than a half of that on soil surface (833 g.m-2) and the fine wood component dominates the canopy samplings (174 g.m-2) while leafy component predominate on soil surface litter (353 g.m-2).

Role of selected riparian herbs in reducing soil erosion and nutrient loss under simulated rainfall

The native riparian herbs such as Leonotis nepetaefolia (L.) R. Br., Cassia tora L., Ageratum conyzoides L., Parthenium hysterophorus L. and Sida acuta burm f., dominant on the bank of River Damodar in Eastern Jharia Area, Dhanbad (India), were selected to assess experimentally their quantitative role in conserving the soil and reducing water runoff and nutrient (N and P) losses. A total of 42.5 mm simulated rainfall were applied at 30 cm h−1 rain intensity on both vegetated and bare plots. The collected runoff water and eroded soil from each plot were determined in terms of soil, water and nutrient conservation value (CV). Among the vegetated plots, soil CV ranged from 30 to 85% and water CV from 20 to 48%. Nutrient (N and P) CV varied from 22 to 65% for total-N, 48 to 80% for ammonia-N and 50 to 86% for nitrate-N. CV for total-P varied from 40 to 62%, inorganic-P from 42 to 60% and organic-P from 20 to 58%. In a stepwise multiple regression equation comprising four independent variables (canopy cover, litter mass, soil moisture and plant biomass), canopy cover explained 70–88% (P < 0.01) of variability in conserving soil, water and nutrient. The losses through runoff water and eroded soil from vegetated plots were found to be minimized to a great extent as compared to bare plots. The role of these species in maintaining the texture and fertility status of riparian soil is discussed.

The effects of fire on the regeneration of a Quercus douglasii stand in Quail Ridge Reserve, Berryessa Valley (California)

Wildfire is an important element in the dynamics of the blue oak (Quercus douglasii) stand. We evaluated the effect of fire in the regeneration of a stand in Quail Ridge. This protected area is located on a peninsula formed by the flooding of Berryessa Valley (California) which has helped it maintain many elements of the native flora. Major vegetation types are blue oak woodland and forest (Q. douglasii, Fagaceae), chamise chaparral (Adenostoma fasciculatum, Rosaceae), and grasslands. In the blue oak stand, 14 plots were randomly located: seven in the burned area and seven outside of the burned areas (control). The effect of fire on sexual regeneration, asexual regeneration, mortality and species composition was analyzed. The fire caused changes in canopy cover, soil cover and litter cover. Asexual regeneration was significantly favored by the fire, but the effect on sexual regeneration was not significant. Fire caused a significant reduction in the basal area of Q. wislizeni and Arctostaphylos manzanita and a reduction in the density of Heteromeles arbutifolia. We concluded that fire does not have a significant effect on the sexual regeneration of Q. douglasii or Q. wislizeni. Fire does stimulate asexual regeneration in both species of oaks, but grazing reduces the regenerative effect of fire. Fire increases regeneration of Arctostaphylos manzanita and Heteromeles arbutifolia by stimulating asexual and sexual regeneration. The occupancies of these chaparral species are further enhanced by their lower palatability compared to both species of oaks.

A new psychodid species from Puerto Rican tank bromeliads

A new species of Neotropical Psychodidae, Alepia zavortinki spec. nov., is reported from tank bromeliads at high elevations in both the Luquillo and Central Mountains of Puerto Rico. Fourth instar larva and adults are described and figured. It is possible to relate larvae and adults because males and females were reared from the larvae and pupae collected from various bromeliads (Vriesea sintenisii and Guzmania berteroniana). Bromeliads are adapted to intercept canopy litter and throughfall water, and decaying litter is washed into and retained by the leaf bases. It is from this aquatic habitat that the larvae and pupae were collected.

Efficiency of extracting microarthropods from the canopy litter in a Japanese cedar (Cryptomeria japonica D. Don) plantation: a comparison between the washing and Tullgren methods

We compared the efficiency of washing versus the Tullgren method for extracting microarthropods from dead leaves and branches in the canopy of Cryptomeria japonica trees. Oribatida and Collembola were consistently the numerically dominant taxa of microarthropods, but the relative abundance differed between the two extraction methods. Oribatida accounted for more than 70% of all the microarthropods collected by the washing method but less than 30% by the Tullgren method. Collembola accounted for less than 10% collected by the washing method but about 60% by the Tullgren method. The density of Oribatida was higher when collected by the washing method than by the Tullgren method, and vice versa for the density of Collembola. Our results suggest that the washing method is appropriate for collecting Oribatida and other microarthropods, whereas the Tullgren method is better for collecting Collembola from the canopy litter of C. japonica trees.

LONG-TERM VEGETATION DYNAMICS IN A CUT WESTERN JUNIPER WOODLAND

Abstract Western juniper (Juniperus occidentalis spp. occidentalis Hook.) expansion in the northern Great Basin has reduced shrubsteppe productivity and diversity. Chainsaw cutting of western juniper woodlands is commonly applied to remove tree interference and restore sagebrush plant communities. Studies assessing understory response following cutting have been limited to early successional stages and have not evaluated the effects of western juniper debris on plant succession. Cutting western juniper produces a large amount of debris which is commonly left on site, occupying a significant portion of treated areas. This study evaluated successional dynamics spanning 13 years after western juniper cutting. Four 0.45-ha blocks were selected on Steens Mountain in southeastern Oregon. Western juniper cover averaged 26% and mature tree density averaged 250 trees · ha−1. Blocks were cut in late summer 1991. Understory standing crop, cover, and density were compared among 3 locations: old canopy litter mats (ca...

Environmental gradients and community attributes underlying biodiversity patterns of semi-arid Mediterranean grasslands

Protection and/or establishment of forest plantation have been used as a management strategy to conserve and stop the deterioration of semi-arid Mediterranean grasslands ecosystems, producing a mosaic of vegetation types. This study was intended to investigate the changes in grassland community in response to protection and forest tree plantation practice as well as to explore the underlying environmental gradients responsible for the observed differences or similarities among these vegetation types. Two multivariate analysis methods including discriminate analysis and non-metric multi-dimensional scaling were used to quantify changes in community composition and attributes following different management practices (free grazing, protection with open grassland, sparse and dense forest tree plantations). This was investigated using species frequency, species abundance, or habitat characteristics. The study results showed that habitat types differed significantly between each other and were significantly separated using multivariate approaches. Discrimination based on habitat characteristics and species composition indicated that protection (or grazing) and light (or shade) explained more than 90% of the observed variability in community changes in response to the protection and forest tree plantation. Also, results indicated that shade effect can be attributed to tree canopy cover and/or litter accumulation on the ground. It could be hypothesized that protection from grazing and afforestation resulted in complex environmental gradients of which shade, litter accumulation as well as protection from grazing disturbance are major constituents. A careful manipulation of protection and afforestation can be used to create a spatially different environmental gradients leading to greater habitat diversity as well as a greater species diversity, and better conservation means of grassland in semi-arid areas.

Diversity and Distribution of Oribatid Mites (Acari: Oribatida) Associated with Arboreal and Terrestrial Habitats in Interior Cedar-Hemlock Forests, British Columbia, Canada

We assessed oribatid mite abundance, species richness and community composition in arboreal and terrestrial habitats associated with 12 western redcedar trees in the Interior Cedar-Hemlock biogeoclimactic zone of British Columbia, Canada. We extracted microarthropods from 36 canopy litter samples, 36 epiphytic lichen samples from three different lichen functional groups, and 36 soil core samples of the forest floor litter layer. Oribatid mites dominated microarthropod assemblages in all habitats. Total microarthropod and oribatid mite abundances were significantly greater in forest floors and foliose (leaf-like) lichens compared to canopy litter accumulations, and alectorioid (hair-like) and cyanolichen (lobed) groups. Sixty-one species of oribatid mites were identified from the study area. The ten species collected from canopy litter and 14 species collected from epiphytic lichens shared five species in common, whereas only three of the 45 species collected from the forest floor also were found within the canopy system. Principal components analysis and discriminant function analysis differentiated three distinct assemblages of oribatid mites corresponding to the canopy litter accumulations, epiphytic lichens and forest floor habitats. Low abundance of oribatid mites in canopy litter accumulations is attributed to low microhabitat structural complexity, low food resources and low desiccation resistance in these habitats compared to canopy lichen habitats and the forest floor. Epiphytic lichens are the domi nant habitat for arboreal oribatid mites in the ICH forest zone, and contribute to the overall biodiversity of the forest system by containing distinct oribatid mite assemblages.