DOI: 10.5061/dryad.ffbg79d25
title: Ecological significance of marcescence in Himalayan plants: Why is standing dead phytomass more important in demanding, resource-limited environments?

description: 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.
description: 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.
description: # 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).