The resorption of phosphorus is greater than that of nitrogen in senescing leaves of vascular epiphytes from lowland Panama

2004 ◽  
Vol 20 (6) ◽  
pp. 693-696 ◽  
Author(s):  
Gerhard Zotz
Keyword(s):  
Plant Growth ◽  
Tropical Forests ◽  
N:P Ratio ◽  
Nutrient Ratios ◽  
Vascular Epiphytes ◽  
Mature Leaves ◽  
P Limitation ◽  
N:P Ratios ◽  
Epiphyte Species ◽  
Nutrient Relations

The epiphytic habitat is assumed to be nutrient deficient, although this generally held notion is based almost completely on circumstantial evidence (Zotz & Hietz 2001). Most studies on the nutrient relations of vascular epiphytes focus on nitrogen (Bergstrom & Tweedie 1998, Hietz & Wanek 2003, Stewart et al. 1995). Although nitrogen plays a key role in limiting plant growth worldwide, there is an on-going discussion whether nitrogen or rather phosphorus are more limiting in many tropical forests (Grubb 1989, Harrington et al. 2001, Vitousek & Howarth 1991). To identify which nutritional factor is most limiting for plant growth, nutrient ratios have been proposed as a very useful tool (Koerselman & Meuleman 1996). These authors stated that N:P ratios exceeding 16 are indicative of P limitation, while an N:P ratio <14 suggests N limitation. Some reports of such ratios in the epiphyte literature indicate that phosphorus may indeed be limiting for epiphytes in tropical forests. For example, the N:P ratio of two field-grown bromeliads (Tillandsia circinnata and T. usneoides) decreased dramatically from 23.6 and 40.4, respectively, to 3.6 and 3.4, respectively, when fertilized with both N and P in the laboratory (Benzing & Renfrow 1974a). On the other hand, however, the average N:P ratios of mature leaves of 41 epiphyte species compiled from a number of papers did not appear particularly high (12.1±10.5, cf. Zotz & Hietz 2001).

THE IMPORTANCE OF HETEROGENEITY OF HABITATS FOR THE SPECIES RICHNESS OF VASCULAR EPIPHYTES IN REMNANTS OF BRAZILIAN MONTANE SEASONAL SEMIDECIDUOUS FOREST

2019 ◽  
Vol 77 (1) ◽  
pp. 99-118
Author(s):  
D. E. F. Barbosa ◽  
G. A. Basílio ◽  
S. G. Furtado ◽  
L. Menini Neto
Keyword(s):  
Species Richness ◽  
Tropical Forests ◽  
Habitat Heterogeneity ◽  
Ecological Functions ◽  
Semideciduous Forest ◽  
Vascular Epiphytes ◽  
Vegetation Heterogeneity ◽  
Initial Hypothesis ◽  
Epiphyte Species ◽  
Seasonal Semideciduous Forest

Epiphytes are an important component of the diversity of tropical forests, and they also have several ecological functions. Vegetation heterogeneity is one of the features responsible for the high biodiversity of the Atlantic Forest, especially in the domain’s seasonal semideciduous forest (SSF). This biodiversity presents as high endemism and species richness. Owing to the seasonal nature of SSF, organisms that require high humidity (e.g. epiphytes) would be expected to show low species richness in these forests. The aims of this study were to conduct a survey of the vascular epiphytes in remnants of montane SSF in the Serra do Ibitipoca, Brazil, and to evaluate the importance of habitat heterogeneity for the richness and composition of species in these areas. We also evaluated whether the intrinsic characteristics of the SSF phytophysiognomy and fragmentation could result in low species richness and a high number of accidental epiphyte species. The study was conducted in the course of 18 expeditions undertaken between September 2013 and December 2016, covering five fragments of montane SSF (totalling 23.6 ha). We recorded 96 species (only one of which is an accidental epiphyte), distributed across 41 genera and 10 families. This is the highest epiphytic species richness recorded in Brazilian SSF to date. The results refuted the initial hypothesis and reinforce the importance to the epiphytic community of conservation of fragments with different structures.

Factors associated with interannual and intraannual variation in nutrient limitation of phytoplankton growth in Castle Lake, California

1995 ◽  
Vol 52 (1) ◽  
pp. 93-104 ◽  
Author(s):  
J. J. Elser ◽  
F. S. Lubnow ◽  
E. R. Marzolf ◽  
M. T. Brett ◽  
G. Dion ◽  
...  
Keyword(s):  
Zooplankton Community ◽  
N:P Ratio ◽  
Phytoplankton Growth ◽  
Limiting Factors ◽  
Data Set ◽  
P Limitation ◽  
N:P Ratios ◽  
Diacyclops Thomasi ◽  
Castle Lake ◽  
Daphnia Rosea

In a 3-year study of Castle Lake, California, potential nutrient (N,P) limitation of phytoplankton growth occurred rapidly (within 1–4 d of ice-out). Both N and P acted as potential limiting factors to phytoplankton growth in short-term (4–5 d) bioassays. Phytoplankton responded strongly to single additions of N or P in 1990 and 1992 but weakly so in 1991. This difference was associated with low inorganic N concentrations during spring 1991. In 1990 and 1991, variation of the primary limiting element correlated with the N:P ratio of the zooplankton community; phytoplankton tended to be N limited when the zooplankton was dominated by species with high N:P ratios (Diaptomus novamexicanus and Diacyclops thomasi: N:P ratios, by mass = 10.6–12.5) but limited by P when low N:P taxa (Daphnia rosea, N:P = 4.7) dominated. However, N vs. P limitation and zooplankton elemental data for 1992 did not fit the 1990–1991 pattern and there was no correlation for the 3-year data set. A field experiment demonstrated that the inorganic N:P ratio (NH4/SRP) increased dramatically with elevated Daphnia grazing but declined significantly with increased Diaptomus; this supported the 1990–1991 correlation between phytoplankton N/P limitation status and zooplankton community elemental ratio.

scholarly journals Vascular epiphytes contribute disproportionately to global centres of plant diversity

2021 ◽  
Author(s):  
Amanda Taylor ◽  
Gerhard Zotz ◽  
Patrick Weigelt ◽  
Lirong Cai ◽  
Dirk Karger ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Plant Diversity ◽  
Vascular Plant ◽  
Substantial Contribution ◽  
Terrestrial Plants ◽  
Latitudinal Diversity Gradient ◽  
Vascular Epiphytes ◽  
Vascular Plant Diversity ◽  
Diversity Gradient ◽  
Epiphyte Species

Aim: Vascular epiphytes are ubiquitous features of wet tropical forests where they contribute substantially to local and regional plant diversity. While some basic epiphyte distribution patterns are relatively well studied, little effort has been made to understand the drivers responsible for constraining their global distribution. This study quantifies the substantial contribution of epiphytes to global gradients and centres of vascular plant diversity and explores whether epiphytes vary from terrestrial plants in relation to contemporary and historical environmental variables. Location: Global. Time period: Present. Major taxa studied: Vascular epiphytes. Methods: We integrated EpiList 1.0, a comprehensive list comprising > 30,000 vascular epiphyte species, and species distributions derived from the GIFT database to describe the global biogeography of epiphytes. We used generalized linear mixed effects models to assess the relationship between epiphytic and terrestrial plant diversity, and contemporary and historical environmental predictors. Results: We find that epiphytes substantially contribute to global centres of vascular plant diversity, accounting for up to 39% of the vascular flora in the Neotropics. Epiphytes decrease in species numbers with increasing latitude at a rate three times faster than terrestrial plants, a trend that is driven mainly by the distribution of tropical forests and precipitation. Further, large regional differences emerge that are explained by several large endemic angiosperm families (e.g., Neotropical Bromeliaceae) that are absent in other tropical regions. Main conclusions: Our results show that epiphytes are disproportionately diverse in most global centres of plant diversity and play an important role in driving the global latitudinal diversity gradient for plants. The distribution of precipitation and tropical forests emerge as major drivers of the latitudinal diversity gradient in epiphyte species richness. Finally, our findings demonstrate how epiphyte floras in different biogeographical realms are composed of different families and higher taxa revealing an important signature of historical biogeography.

Host preferences of low-trunk vascular epiphytes in a cloud forest of Veracruz, Mexico

2005 ◽  
Vol 21 (6) ◽  
pp. 651-660 ◽  
Author(s):  
Klaus Mehltreter ◽  
Alejandro Flores-Palacios ◽  
José G. García-Franco
Keyword(s):  
Water Retention ◽  
Cloud Forest ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Host Preferences ◽  
Host Group ◽  
Vascular Epiphytes ◽  
Lower Trunk ◽  
Tree Ferns ◽  
Epiphyte Species

The diversity, abundance and frequency of vascular epiphytes on the lower trunk were compared between two host groups of a Mexican cloud forest: angiosperm trees (n = 72) and tree ferns (n = 28). The bark of the five most frequent host trees and the root mantle of the two tree ferns were analysed for their thickness, water content, water retention capacity and pH. A total of 55 epiphyte species and 910 individuals were found on the 27 host species. On hosts with a dbh range of 5–10 cm, epiphytes were significantly more diverse (4.3±0.9 species per host) and more abundant (12.5±2.2 individuals per host) on tree ferns than on angiosperm trees (1.9±0.2 species per host and 3.9±0.6 individuals per host). However, these differences were not significant for the dbh class of 10–20 cm, because epiphyte numbers increased on angiosperm trees with larger host size, but not in tree ferns. Most epiphyte species had no preference for any host group, but four species were significantly more frequent on tree ferns and two species on angiosperm trees. The higher epiphyte diversity and abundance on tree fern trunks of the smallest dbh class is attributed to their presumably greater age and to two stem characteristics, which differed significantly between host groups, the thicker root mantle and higher water retention capacity of tree ferns. These bark characteristics may favour germination and establishment of epiphytes.

Warming effects on leaf nutrients and plant growth in tropical forests

Plant Ecology ◽  
2019 ◽  
Vol 220 (7-8) ◽  
pp. 663-674 ◽  
Author(s):  
Ting Wu ◽  
Chao Qu ◽  
Yiyong Li ◽  
Xu Li ◽  
Guoyi Zhou ◽  
...  
Keyword(s):  
Plant Growth ◽  
Tropical Forests ◽  
Leaf Nutrients

THE INHIBITION OF BRUSSELS SPROUT LEAF SENESCENCE BY KININS

1967 ◽  
Vol 45 (7) ◽  
pp. 1019-1024 ◽  
Author(s):  
D. T. Dennis ◽  
M. Stubbs ◽  
T. P. Coultate
Keyword(s):  
Electron Microscopy ◽  
Plant Growth ◽  
Plant Growth Regulators ◽  
Leaf Senescence ◽  
Growth Regulators ◽  
Brussels Sprout ◽  
Cell Organelles ◽  
Leaf Discs ◽  
Mature Leaves ◽  
Young Leaves

The senescence of leaf discs cut from mature Brussels sprout leaves is retarded by a number of kinins. Other plant growth regulators are without effect. When young expanding leaves are treated with kinins the senescence processes appear to be accelerated. The effect of N-6-benzyladenine on the structure of the cell organelles in young and old leaves has been studied by electron microscopy. It has been found that in mature leaves the chloroplast is the organelle which senesces first and the breakdown is retarded by N-6-benzyladenine. The mitochondria are very stable. In young leaves N-6-benzyladenine appears to over-stimulate the chloroplast, causing enlargement and excessive membrane synthesis.

scholarly journals Contribution of Soil and Litter Nutrient Characteristics to Plant Nutrients in a Natural Secondary Mixed Forest in the Qinling Mountains, China

2021 ◽  
Author(s):  
Yue Pang ◽  
Jing Tian ◽  
Lanxin Liu ◽  
Lina Han ◽  
Dexiang Wang
Keyword(s):  
Plant Growth ◽  
Mixed Forest ◽  
Woody Species ◽  
Plant Functional Groups ◽  
Nutrient Concentrations ◽  
Functional Difference ◽  
Qinling Mountains ◽  
Study Region ◽  
Plant Organs ◽  
N:P Ratios

Abstract Soil and litter play important roles in ecosystem nutrient stroage and cycling, which both affect plant growth and ecosystem productivity. However, the potential contributions of soil and litter nutrient characteristics to the nutrient characteristics of different plant functional groups (PFGs) remain unclear. In this study, we investigated the carbon (C), nitrogen (N) and phosphorus (P) concentrations of different organs of three PFGs (trees, shrubs and herbs), litter and soil in nine natural secondary mixed forests in the Qinling Mountains. The results showed that leaves had the highest N and P concentrations and N:P ratios at the organ level, whereas the C:N and C:P values were lowest in leaves. At the PFG level, the N and P concentrations of the same organs in herbaceous plants were significantly higher than those in woody species, while the N:P ratio was significantly lower in herb leaves than in tree and shrub leaves. Tree organs had significantly higher C concentrations and C:N and C:P ratios than shrub and herb organs. The leaf N:P ratios of all PFGs were less than 14, suggested that plant growth was limited by N in the study region. The nutrient contents and stoichiometric ratios in plant organs had different degrees of linkages with those in litter and soil. Soil nutrient characteristics were the main factors affecting the nutrient characteristics of the different PFGs, and litter nutrient characteristics also had important contributions to the nutrient characteristics of PFGs, showing the following order: herbs > trees > shrubs. Our results indicate that the functional difference in plant organs resulted in diverse nutrient concentrations; and varied nutrient connections exist among different ecosystem components. Furthermore, nutrient characteristics of litter and soil can together affect the nutrient characteristics of PFGs.

scholarly journals Regional and temporal patterns of litterfall in tropical South America

2009 ◽  
Vol 6 (4) ◽  
pp. 7565-7597 ◽  
Author(s):  
J. Chave ◽  
D. Navarrete ◽  
S. Almeida ◽  
E. Álvarez ◽  
L. E. O. C. Aragão ◽  
...  
Keyword(s):  
Tropical Forests ◽  
Soil Type ◽  
Net Primary Production ◽  
N:P Ratio ◽  
Reproductive Organs ◽  
Annual Rainfall ◽  
Secondary Forests ◽  
Tropical Rain Forests ◽  
Old Growth ◽  
Leaf Litterfall

Abstract. The production of aboveground soft tissue represents an important share of total net primary production in tropical rain forests. Here we draw from a large number of published and unpublished datasets (n=81 sites) to assess the determinants of litterfall variation across South American tropical forests. We show that across old-growth tropical rainforests, litterfall averages 8.61±1.91Mg/ha/yr. Secondary forests have a lower annual litterfall than old-growth tropical forests with a mean of 8.01±3.41 Mg/ha/yr. Annual litterfall shows no significant variation with total annual rainfall, either globally or within forest types. It does not vary consistently with soil type, except in the poorest soils (white sand soils), where litterfall is significantly lower than in other soil types (5.42±1.91Mg/ha/yr). Litterfall declines significantly with increasing N:P. We also study the determinants of litterfall seasonality, and find that it does not depend on annual rainfall or on soil type. However, litterfall seasonality is significantly positively correlated with rainfall seasonality. Finally, we assess how much carbon is stored in reproductive organs relative to photosynthetic organs. Mean leaf fall is 5.74±1.83 Mg/ha/yr (71% of total litterfall). Mean allocation into reproductive organs is 0.69±0.40Mg/ha/yr (9% of total litterfall). The investment into reproductive organs divided by leaf litterfall is negatively related to the N:P ratio, suggesting that on poor soils, the allocation to photosynthetic organs is prioritized over that to reproduction. Finally, we discuss the ecological and biogeochemical implications of these results.

Association of vascular epiphytes with landscape units and phorophytes in humid lowland forests of Colombian Amazonia

2011 ◽  
Vol 27 (03) ◽  
pp. 223-237 ◽  
Author(s):  
A. M. Benavides ◽  
A. Vasco ◽  
A. J. Duque ◽  
J. F. Duivenvoorden
Keyword(s):  
Species Composition ◽  
Detrended Correspondence Analysis ◽  
Individual Species ◽  
Randomization Tests ◽  
Host Preferences ◽  
Vascular Epiphytes ◽  
Landscape Unit ◽  
Lowland Forests ◽  
Landscape Units ◽  
Epiphyte Species

Abstract:The species composition of vascular epiphytes and phorophytes (trees and lianas) was studied in ten 0.1-ha forest plots distributed over three landscape units (floodplains, swamps and well-drained uplands) in Colombian Amazonia. The aim was to analyse how host-preferences contributed to the patterns in epiphyte assemblages among the landscape units. In the plots 82 species (3310 plants) were holo-epiphytes, 11 species were primary hemi-epiphytes (179 plants) and 61 were secondary hemi-epiphytes (2337 plants). A total of 411 species of tree and liana were recorded as phorophytes. Detrended Correspondence Analysis and Mantel tests showed that the species composition of holo-epiphytes and secondary hemi-epiphytes differed among the landscape units. For both groups the effect of landscape unit on species composition strongly decreased after controlling for the phorophyte composition in the plots. The phorophyte composition significantly explained epiphyte composition and this effect was not removed after accounting for the effect of landscape unit. At the level of individual species, randomization tests yielded only few significant epiphyte–phorophyte associations. For 84% of the epiphyte species the average indicator of patchiness was below 1.5 demonstrating that most epiphyte individuals occurred scattered over different phorophytes. This probably hampered the analyses of host preferences for individual epiphyte species.

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