{'fraction_non_alphanumeric': 0.024096385542168676, 'fraction_numerical': 0.023427041499330656, 'mean_word_length': 4.444444444444445, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Carbon release from woody parts of trees along an elevation gradient in a tropical montane moist forest of Southern Ecuador

Tropical montane forests (TMF), which account for
 21.2% of tropical forests worldwide, are among the
 least studied ecosystems with respect to their C
 balance. The present study aimed to quantify CO2 losses
 from above- and belowground woody organs of
 representative tree species of a tropical montane moist
 forest in southern Ecuador. We used a portable CO2
 measurement system to monitor the respiratory CO2
 release from stems (RS) and coarse roots (RR) along a
 2000 m-elevation transect with three study sites at
 1050, 1890 and 3050 m a.s.l. In an intensive
 1-year-measurement period we determined the impact of
 altitude and of seasonal climate variations on patterns
 of CO2 release from woody organs. We found substantial
 variation in the stem respiratory activity among
 different species and different tree individuals at all
 three study sites. Mean RS declined significantly from
 the premontane forest (1050 m) to the upper montane
 site (3050 m). Mean RR did not change significantly
 with altitude, though showing a decreasing tendency.
 Comparing dry and wet season patterns in stem CO2
 release we found RS to be largely uncoupled from
 changes in the dial temperature regime under humid
 season conditions. During the dry season, the
 respiration-temperature relationship was generally
 stronger, though temperature sensitivity of RS differed
 greatly in degree and even in the direction of response
 among individual trees. Integrating additional
 influencing abiotic factors (vapour pressure deficit,
 wind speed and solar radiation) could not enhance the
 ability to explain the variability of RS. We assumed
 maintenance respiration to dominate under humid
 conditions unfavourable for photosynthetic carbon gain
 of the tree, whereas the dry season conditions
 principally favoured stem respiratory activity, and
 most likely energy acquisition. We found RS, but not RR
 to show a clear seasonality within the measurement
 year. Highest rates were measured during the dry
 season, though the increase in RS could not be simply
 related to changes in the temperature regime. On the
 other hand, the high degree of climate sensitivity of
 RS of the studied montane forest trees could also
 indicate C losses via the alternative pathway
 (cyanide-resistant oxidase), since the higher
 respiratory activity could not satisfactorily be
 related to stimulated cell growth. Along the elevation
 transect, annual carbon efflux from stems decreased
 from 167.1 g C m-2 yr-1 at 1050 m to 37.7 g C m-2 yr-1
 at 3050 m, while coarse root carbon release changed
 little from 1050 m (40.9 g C m-2 yr-1) to 3050 m (36.8
 g C m-2 yr-1). Stem growth respiration accounted for a
 comparatively small fraction of total stem respiration
 at all three sites, whereas coarse root growth
 respiration was of increasing importance with
 increasing altitude.