Ecological significance of marcescence in Himalayan plants: Why is standing dead phytomass more important in demanding, resource-limited environments?
Data files
Jan 18, 2024 version files 136.60 KB
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Chondol_FunEcol_2024_data.xlsx
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README.md
Abstract
- Understanding mechanisms allowing plants to thrive in challenging conditions is critical for predicting their responses to global environmental change. An often overlooked ecological adaptation is marcescence, where leaves and stems are retained beyond their typical shedding time, with implications for nutrient recycling and carbon sequestration. Marcescence may be common in plants with conservative resource-use strategies, especially in environments with limited resources and marked seasonality, such as deserts and alpine regions. However, the extent to which marcescence occurs in different taxa across different habitats and its relationship to seasonality and plant functioning as reflected in ecophysiological traits remains understudied.
- We studied 600 individuals across 40 Himalayan herb species found in desert, steppe, alpine, and subnival habitats, spanning 3000 to 5400 m elevation. Marcescence was observed in 37 out of 40 species evaluated, with 57% of the sampled individuals displaying dead phytomass, indicating the widespread nature of this phenomenon in Himalayan ecosystems.
- Environment and plant traits emerged as significant factors influencing the amount of dead-standing biomass. These findings remained robust after accounting for intraspecific variation and phylogenetic inertia. Desert and steppe species exhibited greater marcescent biomass, characterized by tenfold more dead stem biomass than alpine and subnival plants. In contrast, the proportion of dead phytomass increased with elevation due to increased dead leaf fraction.
- Tall desert species with heavily lignified stems and limited nitrogen and phosphorus content had high levels of stem marcescence, which may aid litter photodegradation and nutrient recycling but also deter herbivory and promote seed dispersal (tumbleweed). Conversely, slow-growing alpine and subnival plants with higher water-use efficiency, foliar C:N ratios, and parenchymatic storage tissue rich in mobile carbohydrates had a high proportion of marcescent leaves, which may aid survival in these resource-limited environments by providing delayed nutrients through moisture-conserving mulch that also provides insulation and protection from frost.
- This study provides new insights into the complex interplay of habitat, seasonality, and plant traits in dead phytomass retention in Himalayan plants. Marcescence is prevalent in resource-conservative species in highly seasonal, resource-limited habitats and may significantly shape the functioning and biodiversity of Himalayan ecosystems.
README: Title of Dataset:
Ecological significance of marcescence in Himalayan plants: Why is standing dead phytomass more important in demanding, resource-limited environments?
Data on dead phytomass and plant traits of 40 Himalayan herb species collected in desert, steppe, alpine, and subnival habitats, spanning 3000 to 5400 m elevation.
Description of the Data and file structure
Data include information for 601 individual plants (the list Individuals) on variables (their z-scores with zero mean and unit variance) for total plant biomass (totBio), total aboveground biomass (totAGB), organ-specific biomass in main plant organs (Roots.live, Leaves.live, Leaf.dead Stems.dead, Stems.live, REF - reproductive parts), the root (RDMC), rhizome (RhDMC), stem (SDMC) and leaf (LDMC) dry matter contents (DMC, dry mass per unit water-saturated fresh mass), and the proportion of marcescent leaves (RatioLeaves) and stems (RatioStems) in total aboveground plant biomass, collected at four different habitats (see column Habitat) at four different times (see column Month): before the start of the growing season in early June (reflecting the amount of remaining dead biomass after the winter season, which lasts from October to May in these cold and arid subtropical Himalayan mountains), during the middle of the growing season in July and August, and after the growing season in late September.
Interspecific data of 40 taxa (the list Species) include species-specific average trait values (their z-scores) for the proportion of marcescent leaves (RatioDeadLeaves) and stems (RatioDeadStems) in total aboveground plant biomass, the root (RDMC), rhizome (RhDMC), stem (SDMC), and leaf (LDMC) dry matter content, as well as mean values for plant height (Height), Bark/xylem ratio, and the content of carbon, nitrogen, and phosphorus in leaves (LCC, LNC, and LPC). To gain insight into the plant's water status and its ability to acquire carbon and nitrogen, we measured stable carbon and nitrogen (δ13C, δ15N) isotope signals from the leaves. We also assessed the levels of nitrogen and phosphorus in roots (RNC and RPC, from merged roots and rhizomes), and we looked at non-structural carbohydrates (totalNSC) in merged root and rhizome samples and individual NSC compounds such as starch, fructans and simple sugars. Furthermore, the proportion of three tissue types serving distinct functional roles—namely, lignified (Mechanical - providing mechanical support), parenchymatic (Storage - used for carbohydrate storage), and conductive (facilitating water transport through vessel conduits)—was recorded as wells as plant age (Longevity) and radial growth rate (Growth).
Methods
This study focused on plant specimens collected from the Ladakh region in the northwest Himalayas of India, covering a vast area of about 80,000 square kilometers with a wide elevational range of vascular plants, ranging from 2650 to 6150 meters above sea level.